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Molecular, biochemical end clinical aspects of peroxisomes biogenesis
disorders
Gootjes, J.
Publication date
2004
Link to publication
Citation for published version (APA):
Gootjes, J. (2004). Molecular, biochemical end clinical aspects of peroxisomes biogenesis
disorders.
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Chapterr 1
Introduction n
Thee disorder currently known as Zellweger syndrome (ZS, MIM# 214100) was first describedd in 1964 in two sib pairs as a familial syndrome of multiple congenital defects.1 In thee following years, two more reports on similar patients were published23 in which the termm cerebro-hepato-renal syndrome was introduced. In 1969, Opitz et al. suggested the namee Zellweger syndrome.4 A major hallmark in the research on Zellweger syndrome was thee discovery by Goldfischer et al. that peroxisomes where absent in the liver and kidney tubuless of Zellweger patients.5 Later, peroxisomes were also found to be deficient in the twoo other disorders neonatal adrenoleukodystrophy (NALD, MIM# 202370) and infantile Refsumm disease (IRD, MIM# 266510). ZS, NALD and IRD together form a spectrum of disease severityy with ZS being the most, and IRD the least severe disorder. The disorders are collectivelyy called peroxisome biogenesis disorders (PBDs). They have an incidence of approximatelyy 1 per 50,000 births.6
Peroxisomes s
Peroxisomess are the last discovered true subcellular organelles. In the 1950s, Rhodin discoveredd these organelles in kidney cells of mice and named them microbodies.7 In 1966, dee Duve et al. found hydrogen peroxide producing as well as degrading enzymes in these microbodiess and therefore named them peroxisomes.8 The significance of peroxisomes remainedd unclear for a long time, until the observation of their absence in Zellweger syndrome.55 Peroxisomes are single-membrane bounded organelles with a diameter of 0.1-1.00 urn. They are found in virtually all eukaryotes, ranging from microorganisms (except archaezoa)) to plants and animals. In humans, peroxisomes are present in every cell, except forr red blood cells. Human cells typically contain several hundred peroxisomes, and they aree most abundant in liver and kidney. They are usually round or oval vesicles, although theyy sometimes appear to form elongated, tubular structures,9 or reticula.10 Peroxisomes havee a very high matrix-protein concentration, sometimes leading to crystalline inclusions.1112 2
Peroxisomee biogenesis
Peroxisomee biogenesis disorders are due to a defect in peroxisome formation. Cell fusion complementationn studies using patient fibroblasts (described later) revealed the existence off 12 distinct genetic groups (complementation groups, CG), representing defects in differentt genes. Currently all of the corresponding PEX genes have been identified. These PEXPEX genes encode proteins involved in the biogenesis of peroxisomes, called peroxins (PEX).. Currently, 29 peroxins have been identified in various species, of which 14 orthologss have been described in humans.
Earlyy studies of PBD cell lines demonstrated a deficiency in peroxisomal matrix protein import,, whereas peroxisomal membrane assembly was relatively normal.1314 In these cells, emptyy peroxisomal membrane remnants that still contain some peroxisomal membrane proteinss (PMPs), but lack most of their internal content, were present, which are called ghosts.. Later studies also reported patient cell lines in which these peroxisomal ghosts
weree absent,1516 which implied a segregation of peroxisomal matrix protein import and peroxisomall membrane biogenesis.
PeroxisomalPeroxisomal membrane biogenesis
Theree has been much controversy on the question how peroxisomes are formed. Accordingg to the earliest model, formation of new peroxisomes occurred by vesicle buddingg from the ER. This hypothesis was based on the electron microscopy observations, showingg that peroxisomes were found in close proximity to the ER.17 Later studies providedd evidence against this postulate, and abundant evidence suggested that peroxisomess multiply by fission of pre-existing peroxisomes (reviewed in Lazarow and Fujiki18).. This model proposes that newly synthesized peroxisomal membrane and matrix proteinss are incorporated in pre-existing peroxisomes. When a certain size is obtained, a neww peroxisome buds off, and the process starts over again (figure 1).
Figuree 1 Overview of the different hypotheticall models of peroxisome biogenesis.. In the model of Lazarow and Fujiki188 new peroxisomes are formed by
buddingg from pre-existing peroxisomes. Inn the model of South and Gould20 for the re-introductionn of peroxisomes in ghost-lesss PEX16 cell lines, PEX16, peroxisomal membranee proteins (PMPs) and matrix proteinss (MP) are inserted subsequently intoo pre-peroxisomes (pp) to form maturee peroxisomes. The model of Titorenko222 involves pre-peroxisomal vesicless (PI and P2) derived from the ER, whichh fuse into P3 vesicles that develop viaa P4 and P5 into mature peroxisomes.
Waterhamm et al. found that peroxisomes in temperature-sensitive mutants of H.
polymporpha,polymporpha, in which peroxisomes were absent when grown at 43°C, but present at 35°C, re-emergedd after a shift from restrictive to permissive temperature.19 Furthermore, South
andd Gould described the re-introduction of peroxisomes into cells of ghost-less PEX16 deficientt human cell lines.20 These results suggest that peroxisomes are not necessarily derivedd from pre-existing peroxisomes. South and Gould proposed a model involving the existencee of (ER independent) preperoxisomal structures into which PEX16 is inserted afterr complementation/transfection (figure 1). After the import of other PMPs this model convergess with the model by Lazarow and Fujiki. However, recent experiments in the yeastt Y. lipolytica by Titorenko et al. indicated a role for the ER in peroxisome biogenesis. Theyy provided experimental evidence indicating that peroxisomes develop in a multistep processs that starts with the formation of pre-peroxisomal vesicles, thought to arise from a subdomainn of the ER, containing components of coat protein II vesicles (figure l).21-22 Inhibitionn with COPI and COPII inhibitors, however, was found to have no effect on peroxisomee formation.2324 Electron microscopy, immunocytochemistry and three-dimensionall image reconstruction of peroxisomes and associated compartments in mouse dendriticc cells also support the involvement of the ER.25 Future studies will show if these resultss are species-specific, or if both models can converge into one hybrid model.
Regardlesss of the way peroxisomes are formed, both models require that PMPs, which aree synthesized on free polyribosomes, are imported into the membrane, probably using a peroxisomall targeting sequence for membrane proteins (mPTS) to facilitate this. mPTSs havee been identified in several integral peroxins and other PMPs in different species (see referencess in Jones et al.26). Available evidence indicates that there is no apparent consensuss sequence. A hydrophilic peptide containing a group of positively charged aminoo acids adjacent to at least one hydrophobic patch or transmembrane domain was observedd several times, although there was no common amino acid sequence among them, andd any individual amino acid could be changed.
Thee mPTSs need to be recognized in the cytosol, after which the PMPs are inserted into thee peroxisomal membrane. Based on the absence of peroxisomal ghosts in cell lines from patientss with defects in PEX3, PEX16 and PEX19,1516-27 it is assumed that the peroxins encodedd by these genes play a role in these processes.
PEX199 is a farnesylated protein that is approximately 95% cytosolic and 5% peroxisomallyy associated.2829 It binds to an array of PMPs of diverse functions,282930313233 includingg peroxins (PEX3, 10, 11,12,13,14,16 and 17) and other PMPs. These results suggest aa role for PEX19 as a soluble mPTS receptor, which is supported by the finding of an overlapp between the regions of PMPs with which PEX19 binds and the mPTSs.28 However, otherss reported cases in which there was no overlap, and suggested a chaperone-like role forr PEX19.3134
Thee PEX3 gene encodes a 42- to 52- kDa membrane protein with its C-terminus facing thee cytosol. Opinions differ on whether the N-terminus is also cytosolic35 or intraperoxisomal.333 The exact function of PEX3 is unclear. It interacts with PEX19 via its C-terminall domain, not with its mPTS,283335-36 and many authors have suggested that PEX3 is requiredd for other membrane-bound peroxins to assemble in the peroxisome membrane (reviewedd in Purdue and Lazarow37) although there is no direct evidence.
PEX166 has two putative membrane-spanning domains and exposes its C- and N-terminall domains to the cytosol.20 Its function is unknown, but it is likely to function upstreamm of PEX3.38 In contrast to PEX3 and PEX19, there is no S. cerevisiae PEX16 ortholog.. Besides humans, the only other organisms in which it has been reported, thus far,, are Y. lipolytica and Arabidopsis thaliana. In Y. lipolytica, PEX16 has different properties thann human ortholog, and plays no role in membrane assembly.39 In A. thaliana, PEX16 has aa role in protein and oil body biogenesis.40
Inn conclusion, there are still many uncertainties with respect to peroxisomal membrane biogenesis.. PEX19 is likely to serve as PMP receptor or chaperone, the functions of PEX3 andd PEX16 are less clear.
ImportImport of peroxisomal matrix enzymes
Likee PMPs, the peroxisomal matrix proteins are synthesized on free polyribosomes in the cytosol,, and posttranslationally imported into the peroxisome. The peroxisomal import machineryy accepts folded proteins, oligomerized proteins and even gold particles fused to importt signals as substrates.4142 To reach their correct cellular location, the peroxisomal matrixx proteins contain specific peroxisomal targeting signals (PTS). More than 90% of all matrixx proteins contain a PTS1, a C-terminal tripeptide with a (S/A/C)-(K/R/H)-L consensuss sequence.43 Later studies found extended sequence lengths as well as species-dependentt ranges of possible conservative exchanges of the residues.44-47 A few matrix
proteinss are targeted by a PTS2, which is located near the N-terminus and has an (R/K)-(L/V/I)-(X)5-(H/Q)-(L/A)) consensus sequence.48 Recently a third PTS was identified in yeast:: PTS3.49 No human PTS3 proteins have been identified so far.
Thee PTSs are bound by receptor proteins in the cytosol which target them to the peroxisomee (figure 2). PEX5 is the receptor for proteins containing a PTS1 or PTS3 and PEX77 is the receptor for proteins containing a PTS2. PEX5 has been described in a wide rangee of species. Mutations in PEX5 have been found as a cause of disease in PBD patients belongingg to CG2.50 PEX5 contains six tetratricopeptide repeats (TPRs) which together constitutee the binding site for the PTS1 of the cargo proteins,51-52 while highly conserved N-terminall pentapeptide repeats were shown to be essential for the interaction with the memberss of the docking complex.5354 The PTS2 receptor PEX7 contains six WD repeats, whichh are each approximately 40 amino acids long and contain a central tryptophan (W)-aspartatee (D) motif. To carry out its receptor function, PEX7 requires help from different species-specificc auxiliary proteins: PEX18 or PEX21 in S. cerevisiae,55 PEX20 in Y.lipolytica56 andd Neurospora crassa,57 or the longer of two splice isoforms of PEX5 (PEX5L) in mammals.58-599 These non-orthologous proteins possess a conserved sequence region that probablyy represents a common PEX7-binding site, suggesting the evolutionary conservationn of a functional module rather than an entire protein.56-58 PEX7 mutations are thee cause of disease in patients belonging to CG11.60 These patients are affected with rhizomelicc chondrodysplasia punctata (RCDP) type 1, a phenotype different from the Zellweger-spectrum.. These patients are only deficient in the few enzymes imported by the
pts2[C>> >7) |5G C{pts1
Figuree 2 Peroxisomal matrix protein import. PEX proteins (peroxins) are depicted as hexagons. Filledd hexagons represent human PEX proteins, open hexagons represent PEX proteins that havee not been identified in humans yet. Dashed arrows depict the extended shuttle model proposedd by Dammai and Subramani.7'1 The PTS2 protein/PEX7/PEX5L complex is imported comparablee to the PTS1 protein/PEX5 complex. See text for details.
PTS22 pathway, and present with proximal shortening of the limbs, periarticular calcifications,, microcephaly, coronal vertebral clefting, dwarfing, congenital cataract, ichthyosiss and severe mental retardation.6
Afterr binding their ligands, PEX5 and PEX7 bind to the components of the docking machineryy (figure 2). The transmembrane proteins PEX13 and PEX14, have been establishedd as members of the docking complex (reviewed in Holroyd and Erdmannftl). PEX133 and PEX14 both provide binding sites for PEX5 and PEX7. It is believed that PEX14 representss the initial docking site for both receptor proteins, because PEX14 has a higher affinityy for cargo-loaded PEX5, whereas PEX13 has a higher affinity for PEX5 alone.62 Moreover,, PEX13 and PEX14 form a complex with cargo-loaded PEX5, but dissociate in thee presence of unloaded PEX5.53 Mutations in PEX13 have been shown to cause the diseasee in CGI3 patients.63 PEX17 has been identified as a peripheral protein in Y.
lipolyticalipolyticaMM and S. cerevisiae65 and as an integral membrane protein in P. pastoris.32 Although theree has been some controversy about PEX17 being involved in PMP import,32 most
evidencee suggests PEX17 to be involved in matrix import only. The protein interacts with PEX14,655 but its exact function is unknown. No human PEX17 has been identified thus far.
Afterr docking of the receptor-cargo complexes, the matrix proteins need to be translocatedd over the peroxisomal membrane (figure 2). The three peroxins PEX2, PEX10 andd PEX12 have been implicated in this process. Mutations in these genes are causing the diseasee in CG10,66 CG767-68 and CG3,69 respectively. All three belong to the family of RING zincc finger proteins, and have been identified in different yeast species and mammals. Theyy are all integral peroxisomal membrane proteins and have a cytosolic carboxy-terminall zinc-binding domain, which is thought to mediate protein-protein interactions. PEX100 and PEX12 interact with each other, and both proteins can also directly bind the PTS11 receptor PEX5.70"72 Moreover, PEX2, PEX5, PEX12 and PEX14 were found in a complexx in rat liver peroxisomes.73 PEX13 is also present in these complexes, but in non-stochiometricc amounts. Cells lacking one of these zinc-binding proteins accumulate PEX5 att the peroxisomal membrane, which suggests these proteins to act downstream of receptorr docking. How the translocation occurs mechanistically, and how the machinery cann accommodate folded and oligomerized proteins is unknown. PEX8 is an intra-peroxisomall peroxin, first identified in H. polymorpha74 and so far cloned in several yeast speciess only. It behaves like a peripheral peroxisomal membrane protein in P. pastoris/5 Y.
HpolyticaHpolyticaMM and S. cerevisiae,76 whereas it is localized in the peroxisomal matrix in H. polymorpha.polymorpha.7474 All orthologs contain a PTS1 at the carboxy-terminus; H. poJymorpha PEX8 alsoo contains a PTS2. PEX8 directly interacts with PEX5, independent of its PTS1,76
althoughh it has not been shown if this interaction takes place inside the peroxisome. Since PEX88 contains a PTS1 and in H. polymorpha also a PTS2, it has been suggested to be involvedd in the dissociation of the cargo from the PTS receptors or in the subsequent recyclingg of the receptors,76 although others have implicated PEX8 in the association of the dockingg complex with the translocation complex.77
Initially,, the general model for peroxisomal matrix protein import proposed that the PTSS receptors recycle right back into the cytosol after dropping their cargo at the docking site.788 However, recent experiments indicate that PEX5 enters human peroxisomes during thee course of its function, and then re-emerges into the cytosol to carry out another round off import: the extended shuttle model (figure 2).79 Dammai and Subramani elegantly demonstratedd the proteolytic cleavage of a PEX5 fusion protein within peroxisomes and
detectedd the processed PEX5 in the cytosol. These experiments, however, cannot exclude thatt the fusion protein has only been inserted into the membrane with its amino-terminal sitee accessible to the protease, without actual transport across the membrane. Moreover, thee complete translocation of PEX5 would imply the presence of a, yet unknown, PEX5 exportt machinery.
Afterr translocation of the cargo proteins, the PTS receptors PEX5 and PEX7 need to recyclee back to the cytosol for another cycle of protein import (figure 2). PEX1 and PEX6 havee been implicated in this recycling, and are both members of the AAA protein family (ATPasess associated with a various cellular activities). These proteins contain highly conservedd AAA domains of 230 amino acids, which contain Walker ATP binding sequencess and have ATP activity. Mutations in the genes encoding these proteins are disease-causingg in CGI8081 and CG4,82 respectively. Both proteins were found to interact withh each other.83 Localization studies have shown remarkable differences between variouss organisms. The proteins have been found peroxisomally associated and/or cytosolic,, and also present in vesicles distinct from mature peroxisomes.22-83'87 Cell lines defectivee in PEX1 and PEX6 have a defect in the import of matrix proteins.88 They are both importantt for the stability of PEX5,78-84 and they function in the terminal steps of the matrix proteinss import pathway.89 However, because other members of the AAA family are involvedd in membrane fusion processes90 and in some organisms PEX1 and PEX6 were foundd present in vesicles distinct from mature peroxisomes, they were also suggested to bee involved in the fusion of these small vesicles, leading to the maturation of peroxisomes.22833 Very recently, two proteins interacting with PEX1 and PEX6 have been reported.. In S. cerevisiae, PEX15 was described as an integral membrane protein that binds PEX66 in an ATP-dependent manner.91 In humans, the transmembrane protein PEX26 was discoveredd to cause the disease in PBD patients of CG8.92 This protein was shown to anchorr PEX6 and PEX1 to the peroxisomal membrane, in a PEX6-dependent manner. Later studiess showed that in human cell lines defective of PEX26, catalase and PTS2 protein importt was disturbed but PTS1 protein was normal,93 which makes the role of PEX26 and thee moment of action of PEX1 and PEX6 unclear.
PEX44 is a peripherally associated peroxisomal membrane protein, located at the cytosolicc face of the peroxisome. The protein is kept at the peroxisomal membrane via interactionn with PEX22, an integral peroxisomal membrane protein.94 In cell lines defective inn these proteins, PEX5 protein level was severely decreased.89 Both PEX4 and PEX22 are involvedd in the import of peroxisomal matrix proteins,9495 and act in the final step, after PEX11 and PEX6,89 suggesting a role in receptor recycling. Their exact functions, however, aree still unclear. No human PEX4 and PEX22 have been identified so far.
PeroxisomePeroxisome proliferation
PEX111 has been postulated to play a regulatory role in peroxisome proliferation, based on thee finding that cells lacking PEX11 contain few giant peroxisomes and appear to be unablee to segregate the giant peroxisomes to daughter cells.96 When PEX11 is overexpressed,, hyperproliferation occurs.9798 However, PEX11 was also found to play a metabolicc role in peroxisomal B-oxidation in S. cerevisiae." These authors suggested the rolee of PEX11 in peroxisome division to be secondary due to ongoing B-oxidation. Recently,, both the dynamin-like protein Vsplp (DLP1 in humans)100101 and the newly identifiedd PEX25 and PEX27102104 in S. cerevisiae were shown to be involved in peroxisome
proliferation.. Cells lacking these proteins had fewer and larger peroxisomes. The C-terminii of PEX25 and PEX27 are similar to the entire PEX11.104 Some of the cells lacking PEX255 had no peroxisomes detectable with immunofluorescence with antibodies against PTS1-- or PTS2-containing matrix proteins.102 Yeast two-hybrid analyses showed that PEX277 interacts with PEX25 and itself, PEX25 interacts with PEX27 and itself, and PEX11 interactss only with itself.103 Furthermore, in cells deleted for two other peroxins in S.
cerevisiae,cerevisiae, PEX28 and PEX29, peroxisomes are increased in number, exhibit extensive clustering,, are smaller in area than peroxisomes of wild-type cells, and often exhibit
membranee thickening between adjacent peroxisomes in a cluster.105 This implies a role for thesee two peroxins in peroxisome dynamics. Thus, PEX11, PEX25, PEX27, PEX28, PEX29 andd Vpslp/DLPl are candidates for a role in the regulation of peroxisome number, size, andd distribution. The underlying mechanisms, however, are still unclear.
Peroxisomall functions
Peroxisomess are involved in a number of essential metabolic functions in humans. The majorr functions are:
P-oxidationP-oxidation of fatty acids and fatty acid derivatives
Thee peroxisome handles the p-oxidation of many substrates. These include very-long chainn fatty acids (VLCFAs), notably C26:0, the branched chain fatty acids, such as pristanic acid,, the bile acid intermediates di- and trihydroxycholestanoic acid (DHCA and THCA), somee long chain fatty acids and long chain dicarboxylic acids (products of ©-oxidation), andd the side chains of eicosanoids.106 Furthermore, it has become clear that the peroxisomall p-oxidation system is also involved in the last step of the biosynthesis of the poly-unsaturatedd fatty acid docosahexaenoic acid (DHA).107
PhytanicPhytanic acid a-oxidation
Phytanicc acid and other 3-methyl-branched fatty acids are taken up from the diet with dairyy products, meat and fish being the most important sources. These compounds cannot bee degraded by the normal peroxisomal p-oxidation pathway, because of the methyl groupp on the C3 position. Therefore, they are broken down by the peroxisomal a-oxidation system.1088 Phytanic acid is thereby broken down to pristanic acid, which can be degraded by P-oxidation.. The deficiency in the second enzyme of phytanic acid a-oxidation: phytanoyl-CoAA hydroxylase, leads to Refsum disease [MIM# 266500].
Ether-phospholipidsEther-phospholipids biosynthesis
Thee first two steps in the ether-phospholipid biosynthesis, catalyzed by the enzymes dihydroxyacetonephosphatee acyltransf erase (DHAPAT) and alkyl-dihydroxyacetonephosphate-synthasee (alkyl-DHAP-synthase), take place in the peroxisomes.. Deficiencies in these two enzymes in humans lead to RCDP type 2 [MIM# 222765]] and RCDP type 3 [MIM# 600121], respectively. In mammals, the main end-productss of the ether-phospholipid biosynthetic pathway are the plasmalogens, which are characterizedd by the presence of an alkenyl group at the sn-1 position of the glycerol backbone.. Plasmalogens are components of cellular membranes, make up approximately halff of the heart's phospholipids, but are most abundant in nervous tissue. They make up
Generall introduction approximatelyy 80 to 90% of the ethanolamine phospholipid class in myelin. Furthermore, plasmalogenss are decreased in the affected areas of the brain of Alzheimer's patients.109 However,, the functional significance of plasmalogens is unknown.
OtherOther peroxisomal functions
Otherr metabolic pathways that take place inside peroxisomes, at least partly, are L-pipecolicc acid oxidation, glyoxylate metabolism, D-amino acid metabolism, hydrogen peroxidee metabolism, purine metabolism and fatty acid chain elongation. Although the involvementt of peroxisomes in the biosynthesis of isoprenoid/cholesterol biosynthesis was generallyy accepted for many years,110 recent data strongly suggest that peroxisomes are not involvedd inhuman isoprenoid/cholesterol biosynthesis.111112
PBDD Phenotypes
Ass described in the introduction, the peroxisome biogenesis disorders form a disease spectrumm comprising of the three disorders Zellweger syndrome, neonatal adrenoleukodystrophyy and infantile Refsum disease.
ZellwegerZellweger syndrome
Thee cerebro-hepato-renal syndrome of Zellweger is the most severe PBD, and is characterizedd by the complete absence of functional peroxisomes and peroxisomal functions.. Patients display a characteristic facial appearance with a large anterior fontanel, highh forehead, hypoplastic supraorbital ridges, epicanthal folds and a broad nasal bridge. Ocularr abnormalities include cateracts, glaucoma, corneal clouding, Brushfield spots, pigmentaryy retinopathy and optic nerve dysplasia. Sensorineural deafness is often present andd patients are mentally retarded. Additionally, there is severe hypotonia, weakness and neonatall seizures. The development of internal organs (brain, liver, kidney) and the skeletonn is disturbed. Radiologic examination reveals abnormal punctuate calcifications in thee patella and epiphyses of the long bones. Renal cysts are common. Most patients die withinn the first year of life.6
NeonatalNeonatal adrenoleukodystropy
NALDD was first described by Ulrich et al. as connatal ALD in a boy who presented at birth withh hypotonia, convulsions, absent grasp reflex, slight Moro response, and little spontaneouss movements.113 He showed all signs diagnostic of ALD, including the characteristicc demyelination of the central nervous system white matter, atrophy of the adrenall cortex, ballooned adrenocortical cells and splinter-like lamellar elements composedd of electron-dense leaflets separated by a clear space. NALD should not be confusedd with X-linked adrenoleukodystrophy (X-ALD, MIM# 300100), which is not a peroxisomee biogenesis disorder, but a defect in the ABCD1 gene resulting in a deficiency inn the peroxisomal B-oxidation and accumulation of VLCFAs. To distinguish between ZS andd NALD, Kelley et al. defined criteria to distinguish between the two disorders.114 Althoughh many cases could be classified by these criteria, a number of patients remained withh symptoms of both disorders. However, since it is now firmly established that the PBDss form a disease continuum, NALD is now defined as a less severe form of ZS,
involvingg progressive white matter disease, with patients surviving from several months off life u p until their mid-teens.
InfantileInfantile Refsum disease
IRDD is the mildest phenotype of the PBDs. It was first described by Scotto and co-workers inn three cases of young children presenting with several neurological abnormalities and hepatomegaly.1155 Initially, IRD was thought to be a variant of Refsum disease, a single enzymee defect, in which phytanic acid accumulates. However, later studies revealed the presencee of a general peroxisomal dysfunction,116 which was confirmed by the absence of peroxisomess in liver.117 Patients with IRD have external features reminiscent of ZS, but no neuronall migration disorder, and no progressive white matter disease. Their cognitive and motorr development varies between severe global handicap and moderate learning disorderr with deafness and visual impairment due to retinopathy. Their survival is variable.. Most patients with IRD reach childhood and some even reach adulthood.
Diagnosiss of PBDs
BiochemicalBiochemical analysis
Thee laboratory diagnosis of a PBD starts with the analysis of various parameters in plasma (concentrationss of VLCFAs, pristanic acid, phytanic acid, bile acid intermediates, unsaturatedd fatty acids and L-pipecolic acid) and erythrocytes (plasmalogens and poly-unsaturatedd fatty acids).118 When a PBD is suspected, this is followed by the measurement off various parameters in cultured skin fibroblasts (VLCFA concentration, C26:0 and pristanicc acid p-oxidation, phytanic acid a-oxidation, DHAPAT activity and immunoblot analysiss to assess the peroxisomal processing of the P-oxidation enzymes straight chain acyl-CoAA oxidase and 3-ketoacyl-CoA thiolase). The diagnosis is completed by immunofluorescencee microscopy with antibodies against the peroxisomal enzyme catalase,, to confirm the absence of peroxisomes, and with antibodies against the peroxisomall membrane protein ALDP to reveal the presence or absence of peroxisomal ghosts. .
noo complementation: CG
CG11 CG? -* l i # v - \ complementation: repeatt with other CGs Figuree 3 Complementation analysis. Cells from a new patient are fused with cells from a patient
belongingg to a known complementation group (CG). When no complementation occurs, the defectivee genes in both patients are the same. Otherwise, the procedure is repeated with other CGs. .
ComplementationComplementation analysis
Whenn the diagnosis of a PBD is established, cell fusion complementation analysis is performed,, to identify the defective PEX gene.119 In this technique, fibroblasts from a new
patientt are fused with cells from a patient belonging to a known complementation group, therebyy combining the genetic information of both patients (figure 3). When the cells do nott complement each other and there is no restoration of peroxisome formation, the defectivee genes in both patients are the same. If peroxisomes are formed, the defective genee in both patients is different. Peroxisome formation is assayed by catalase immunofluorescencee microscopy.
InIn our laboratory, so far, 246 PBD patients have been assigned to the 12 different complementationn groups (table 1). The percentages in this table are comparable to the data inn literature.6 Most complementation groups are associated with more than one clinical phenotype.1200 The large majority of the patients belong to CGI, caused by mutations in the PEX1PEX1 gene. The second most common CG is CG4, in which PEX6 is defective. Together, defectss in these two AAA-ATPases account for more than 70% of the PBD patients.
Tablee 1 Complementation groups in Amsterdam
Complementationn Group KKI' ' 1 1 2 2 3 3 4 4 7 7 8 8 9 9 10 0 11 1 12 2 13 3 14 4 Gifub b E E C C B B A A D D F F R R G G H H J J Gene e PEX1 1 PEX5 5 PEX12 2 PEX6 6 PEX10 0 PEX26 6 PEX16 6 PEX2 2 PEX7 7 PEX3 3 PEX13 3 PEX19 9 Patients s 174 4 5 5 16 6 31 1 3 3 4 4 2 2 7 7 n.i. . 0 0 2 2 2 2 %« « 59 9 2 2 6 6 12 2 1 1 2 2 1 1 3 3 n.i. . 0 0 1 1 1 1
aa Kennedy Krieger institute, Baltimore, USA, b Gifu
univeristy,, Gifu, Japan, ' % of cell lines complemented withh this CG, CG11 was excluded, n.i. not included
MutationsMutations in the PEX genes
Mutationn analysis has been performed in all of the complementation groups.6 Only for twoo mutations in CGI (PEX1) a high allele frequency has been found. The first mutation is aa point mutation 2528G>A causing the missense mutation G843D.8081 This mutation attenuatess the activity of the protein and is associated with the mild IRD phenotype. It reducess the binding ability between PEX1 and PEX6.121 The G843D allele frequency ranges fromm 25% to 37% in the different cohorts.80122-126 The second mutation is the insertion 2097-2098insT,, which results in a frameshift and low steady state PEX1 mRNA levels.122125 At thee protein level it leads to truncation of the PEX1 protein within the protein's second AAAA domain, abolishing its PEX1 activity. It is associated with the severe ZS phenotype. Thiss mutation has an allele frequency of around 30%.122125126 Together, these mutations accountt for around 60% of all PEX1 alleles, which is about 40% of all PBD alleles. Furthermore,, in the Japanese population, a common mutation in PEX10 has been found, duee to a founder effect.127 This 2-bp deletion 814-815delCT is present in a homozygous formm in all 11 Japanese PEX10 patients. Most of the other mutations found in the PEX geness are unique to one patient or family.
TemperatureTemperature sensitivity
Studiess in fibroblasts of patients with milder forms of PBDs (IRD and some NALD patients)) have shown temperature sensitivity of biochemical parameters.128 In these cells, a (partial)) restoration of peroxisome formation and peroxisome function was observed, whenn cells were cultured at 30°C instead of 37°C. This phenomenon has been reported for patientss belonging to CGI (PEX1),12-3 CG4 (PEX6),129 CG8 (PEX26),130 CG10 (PEX2),128 and CG133 (PEX13)131 and is associated with specific (point-)mutations.
Therapy y
Becausee the peroxisome biogenesis disorders have a genetic origin, and multiple malformationss and neocortical alterations in the brain originate prenatally, treatment of patientss is limited, but there are possibilities for treatment of symptoms, especially for patientss with milder phenotypes. The treatment strategies can be divided into two groups: correctionn of biochemical deficiencies or accumulations, and pharmacological induction of peroxisomes. .
Too correct plasmalogen levels, ether lipids have been administered orally, which resultedd in a partial normalization of red blood cell plasmalogen levels.132 The high VLCFA couldd be (partially) corrected by a diet also used in the treatment of X-ALD,133 which also normalizedd phytanic acid levels.6 To correct DHA levels, cholic and chenodeoxycholic acidss have been administered, which resulted in improved liver function and improvementt in neurologic status.134 Another approach to correct DHA levels was by administeringg DHA ethyl ester,135 which resulted in a normalization of DHA levels and liverr function, improvement of vision and muscle tone, as well as improvement of myelinationn as studied by MRI.136 The effect was the largest in patients who started the treatmentt before 6 months of age. In addition to the DHA correction, VLCFA levels decreasedd and plasmalogen levels increased. The decreased levels of a-tocopherol that are foundd in many patients can be corrected by oral vitamin E suppletion.
Inductionn of peroxisomes has been tried by the administration of the peroxisomal proliferatorr clofibrate. Although this did have effects in rodents, it did not have any result inn humans.137138 The peroxisome proliferator sodium 4-phenylbutyrate has only been testedd in human fibroblasts yet, but did show promising results.139 After treatment of PBD fibroblasts,, an approximate two-fold increase in peroxisome number was observed. In NALDD and IRD fibroblasts there was an increase in very-long-chain fatty acid p-oxidation andd plasmalogen concentrations, and a decrease in very-long-chain fatty acid concentrations.. No clinical studies with this compound have been performed yet.
Inn conclusion, although many defects in PBD patients originate prenatally, symptomaticc treatment was found to be beneficial in patients, and new strategies like the administrationn of 4-phenylbutyrate, are being investigated that might result in the upregulationn of peroxisomes in patients.
Outlinee of this thesis
Itt is evident that our knowledge of peroxisome biogenesis, peroxisomal functions and the peroxisomee biogenesis disorders has expanded enormously since the discovery of peroxisomess in the 1950s. Many peroxins, indispensable for peroxisome formation, have
beenn identified and a 'corner of the veil has been lifted' about how these peroxins function. Muchh has been learned about the metabolic pathways that function inside the peroxisomes.. Furthermore, many PBD patients have been described, and the initial idea of threee or more separate peroxisomal disorders had been abandoned, and it is now clear thatt the disorders form a disease spectrum and originate from defects in the same genes, whichh is why they are now collectively called the peroxisome biogenesis disorders.
Thiss marked genetic heterogeneity and the presence of many unique mutations among patientss with a PBD are causing complications in genotype-phenotype studies. Therefore, in chapterr two propose to use a different approach to predict the life expectancy of the patients: byy examining the effects of the defective genes on peroxisome function, rather that the mutationss themselves. Therefore we conducted a search for suitable biochemical parameters, whichh would be best in predicting the severity of patients. In chapter three and four, we reportt novel mutations in the PEX2 and PEX12 genes of PBD patients, shedding new light onn the differences in importance of the zinc-binding domains in the proteins encoded by thesee genes. Chapter five describes eight PBD patients with a very unusual biochemical phenotype,, characterized by abnormal peroxisomal plasma metabolites, but normal to veryy mildly abnormal parameters in cultured skin fibroblasts, including a mosaic catalase immunofluorescencee pattern, which so far made complementation analysis impossible. Wee developed a novel complementation technique and characterized the patients. In chapterr six the reinvestigation of a unique patient is described, who was reported with a presumedd deficiency in THCA-CoA oxidase, but instead was found to be suffering from a mildd PBD, although peroxisomes in fibroblasts appeared normal. Chapter seven describes a rapid,, non-invasive alternative technique to determine the presence of peroxisomes in patientt cells: immunofluorescence microscopy analysis in lymphocytes, which can be isolatedd from the same blood samples as used for metabolite analyses. In chapter eight, we reportt all mutations in the different PEX genes that have been determined in our laboratoryy so far, combined with those reported in literature.
References s
1.. Bowen P., Lee C.S.N., Zellweger H. and Lindenberg R. (1964) A familial sndrome of multiple congenital anomalies.. Bull Johns Hopkins Hosp 114: 402-414.
2.. Smith D.W., Opitz J.M and Inhorn S.L. (1965) A syndrome of multiple developmental defects including polycysticc kidneys and intrahepatic biliary dysgenesis in 2 siblings. J.Pediatr. 67: 617-624.
3.. Passarge E. and McAdams AJ. (1967) Cerebro-hepato-renal syndrome. A newly recognized hereditary disorderr of multiple congenital defects, including sudanophilic leukodystrophy, cirrhosis of the liver, andd polycystic kidneys. J.Pediatr, 71: 691-702.
4.. Opitz J.M., ZuRhein G.M., Vitale L., Shahidi N T . , Howe J., Chon S., Shanklin D., Sybers Hv Dood A.
andd Gerritsen T. (1969) The Zellweger syndrome (cerebrohepatorenal syndrome). Birth Defects 5: 144-158. .
5.. Goldfischer S., Moore C.L., Johnson A.B., Spiro AJ., Valsamis M.P., Wisniewski H.K., Ritch R.H., Nortonn W.T., Rapin I. and Gartner L.M. (1973) Peroxisomal and mitochondrial defects in the cerebro-hepato-renall syndrome. Science 182: 62-64.
6.. Gould S.J., Raymond G.V. and Valle D. (2001) The peroxisome biogenesis disorders. In: Scriver C.R., Beaudett A.L., Valle D. and Sly W.S. (eds.) The metabolic and molecular bases of inherited disease. McGraw-Hill,, New York, 3181-3217.
7.. Rhodin J. (1954) Correlation of ultrastructural organisation and function in normal and experimentally changedd proximal convoluted tubule eels of the mouse kidney.
8.. de Duve C. and Baudhuin P. (1966) Peroxisomes (microbodies and related particles). Physiol Rev. 46: 323-357. .
9.. Schrader ML, Burkhardt J.K., Baumgart E., Luers G., Spring Hv Volkl A. and Fahimi H.D. (1996)
Interactionn of microtubules with peroxisomes. Tubular and spherical peroxisomes in HepG2 cells and theirr alterations induced by microtubule-active drugs. Eur.J.Cell Biol, 69: 24-35.
10.. Gorgas K. (1984) Peroxisomes in sebaceous glands. V. Complex peroxisomes in the mouse preputial gland:: serial sectioning and three-dimensional reconstruction studies. Anat.Embryol.(Berl) 169: 261-270. 11.. Veenhuis M., Harder W., van Dijken J.P. and Mayer F. (1981) Substructure of crystalline peroxisomes in
methanol-grownn Hansenula polymorpha: evidence for an in vivo crystal of alcohol oxidase. Mol.Cell
Biol.Biol. 1: 949-957.
12.. Goldfischer S. and Reddy J.K. (1984) Peroxisomes (microbodies) in cell pathology. Int.Rev.Exp.Pathol. 26: 45-84. .
13.. Santos M.J., Imanaka T., Shio H., Small G.M. and Lazarow P.B. (1988) Peroxisomal membrane ghosts in Zellwegerr s y n d r o m e - a b e r r a n t organelle assembly. Science 239: 1536-1538.
14.. Santos M.J., Imanaka T., Shio H. and Lazarow P.B. (1988) Peroxisomal integral membrane proteins in controll and Zellweger fibroblasts. J.Biol.Chem. 263:10502-10509.
15.. Honsho M., Tamura S., Shimozawa N., Suzuki Y., Kondo N. and Fujiki Y. (1998) Mutation in PEX16 is causall in the peroxisome-deficient Zellweger syndrome of complementation group D. Am.J.Hum.Genet.
63:: 1622-1630.
16.. Matsuzono Y., Kinoshita N., Tamura S„ Shimozawa N., Hamasaki M., Ghaedi K„ Wanders R.J., Suzuki Y.,, Kondo N. and Fujiki Y. (1999) Human PEX19: cDNA cloning by functional complementation, mutationn analysis in a patient with Zellweger syndrome, and potential role in peroxisomal membrane assembly.. Proc.Natl.Acad.Sci.U.S.A 96: 2116-2121.
17.. Novikoff A. and Shin W. (1964) The endoplasmic reticulum in the Golgi zone and its relations to microbodies,, Golgi-apparatus and autophagic vacuoles in rat liver cells. J.Microscopy 3: 187-206.
18.. Lazarow P.B. and Fujiki Y. (1985) Biogenesis of peroxisomes. Annu.Rev.Cell Biol. 1: 489-530.
19.. Waterham H.R., Titorenko V.I., Swaving G.J., Harder W. and Veenhuis M. (1993) Peroxisomes in the methylotrophicc yeast Hansenula polymorpha do not necessarily derive from pre-existing organelles.
EMBOEMBO J. 12: 4785-4794.
20.. South S.T. and Gould S.J. (1999) Peroxisome synthesis in the absence of preexisting peroxisomes. J.Cell
Biol.Biol. 144: 255-266.
21.. Titorenko V.I. and Rachubinski R.A. (2001) The life cycle of the peroxisome. Nat.Rev.Mol.Cell Biol. 2: 357-368. .
22.. Titorenko V.I., Chan H. and Rachubinski R.A. (2000) Fusion of small peroxisomal vesicles in vitro reconstructss an early step in the in vivo multistep peroxisome assembly pathway of Yarrowia lipolytica.
J.CellJ.Cell Biol. 148: 29-44.
23.. Voorn-Brouwer T., Kragt A., Tabak H.F. and Distel B. (2001) Peroxisomal membrane proteins are properlyy targeted to peroxisomes in the absence of. J.Cell Sci. 114: 2199-2204.
24.. South S.T., Sacksteder K.A., Li X., Liu Y. and Gould SJ. (2000) Inhibitors of COPI and COPII do not blockk PEX3-mediated peroxisome synthesis. J.Cell Biol. 149: 1345-1360.
25.. Geuze H.J., Murk J.L., Stroobants A.K., Griffith J.M., Kleijmeer M.J., Koster A.J., Verkleij A.]., Distel B. andd Tabak H.F. (2003) Involvement of the endoplasmic reticulum in peroxisome formation. Mol.Biol.Cell
14:: 2900-2907.
26.. Jones J.M., Morrell J.C. and Gould S.J. (2001) Multiple distinct targeting signals in integral peroxisomal membranee proteins. J.Cell Biol. 153:1141-1150.
27.. Shimozawa N., Suzuki Y., Zhang Z., Imamura A., Ghaedi K., Fujiki Y. and Kondo N. (2000) Identificationn of PEX3 as the gene mutated in a Zellweger syndrome patient lacking peroxisomal remnantt structures. Hum.Mol.Genet. 9: 1995-1999.
28.. Sacksteder K.A., Jones J.M., South S.T., Li X., Liu Y. and Gould S.J. (2000) PEX19 binds multiple peroxisomall membrane proteins, is predominantly cytoplasmic, and is required for peroxisome membranee synthesis. J.Cell Biol. 148: 931-944.
29.. Snyder W.B., Faber K.N., Wenzel T.J., Koller A., Luers G.H., Rangell L., Keller G.A. and Subramani S. (1999)) Pexl9p interacts with Pex3p and PexlOp and is essential for peroxisome biogenesis in Pichia pastoris.. Mol.Biol.Cell 10: 1745-1761.
30.. Gotte Kv Girzalsky W., Linkert M., Baumgart E., Kammerer S., Kunau W.H. and Erdmann R. (1998)
Pexl9p,, a farnesylated protein essential for peroxisome biogenesis. Mol.Cell Biol. 18: 616-628.
31.. Snyder W.B., Koller A., Choy A.J. and Subramani S. (2000) The peroxin Pexl9p interacts with multiple, integrall membrane proteins at the peroxisomal membrane. J.Cell Biol. 149:1171-1178.
32.. Snyder W.B., Koller A., Choy A.J., Johnson M.A., Cregg J.M., Rangell L., Keller G.A. and Subramani S. (1999)) Pexl7p is required for import of both peroxisome membrane and lumenal proteins and interacts
withh Pexl9p and the peroxisome targeting signal-receptor docking complex in Pichia pastoris.
Mol.Biol.CellMol.Biol.Cell 10:4005-4019.
33.. Soukupova M , Sprenger C , Gorgas K., Kunau W.H. and Dodt G. (1999) Identification and characterizationn of the human peroxin PEX3. Eur.j.Cell Biol. 78: 357-374.
34.. Fransen M., Wylin T., Brees C., Mannaerts G.P. and Van Veldhoven P.P. (2001) Human pexl9p binds peroxisomall integral membrane proteins at regions distinct from their sorting sequences. Mol.Cell Biol.
21:: 4413-4424.
35.. Ghaedi K., Tamura S., Okumoto K., Matsuzono Y. and Fujiki Y. (2000) The peroxin pex3p initiates membranee assembly in peroxisome biogenesis. Mol.Biol.Cell 11: 2085-2102.
36.. Muntau A.C., Mayerhofer P.U., Paton B.C., Kammerer S. and Roscher A.A. (2000) Defective peroxisome membranee synthesis due to mutations in human PEX3 causes Zellweger syndrome, complementation groupp G. Am.J.Hum.Cenet. 67: 967-975.
37.. Purdue P.E. and Lazarow P.B. (2001) Peroxisome biogenesis. Annu.Rev.Cell Dev.Biol. 17: 701-752. 38.. Honsho M., Hiroshige T. and Fujiki Y. (2002) The membrane biogenesis peroxin Pexl6p. Topogenesis
andd functional roles in peroxisomal membrane assembly. J.Biol.Chem. Til: 44513-44524.
39.. Eitzen G.A., Szilard R.K. and Rachubinski R.A. (1997) Enlarged peroxisomes are present in oleic acid-grownn Yarrowia lipolytica overexpressing the PEX16 gene encoding an intraperoxisomal peripheral membranee peroxin. J.Cell Biol 137:1265-1278.
40.. Lin Y„ Sun L., Nguyen L.V., Rachubinski R.A. and Goodman H.M. (1999) The Pexlóp homolog SSE1 andd storage organelle formation in Arabidopsis seeds. Science 284: 328-330.
41.. McNew J.A. and Goodman J.M. (1994) An oligomeric protein is imported into peroxisomes in vivo.
J.CellJ.Cell Biol. 127: 1245-1257.
42.. Walton P.A., Hill P.E. and Subramani S. (1995) Import of stably folded proteins into peroxisomes.
Mol.Biol.CellMol.Biol.Cell 6: 675-683.
43.. Gould S.J., Keller G.A., Hosken N., Wilkinson J. and Subramani S. (1989) A conserved tripeptide sorts proteinss to peroxisomes. J.Cell Biol. 108:1657-1664.
44.. Elgersma Y., Vos A., Van den B.M., van Roermund C.W., van der S.P., Distel B. and Tabak H.F. (1996) Analysiss of the carboxyl-terminal peroxisomal targeting signal 1 in a homologous context in Saccharomycess cerevisiae. J.Biol.Chem. 271: 26375-26382.
45.. Lametschwandtner G., Brocard C , Fransen M., Van Veldhoven P., Berger J. and Hartig A. (1998) The differencee in recognition of terminal tripeptides as peroxisomal targeting signal 1 between yeast and h u m a nn is due to different affinities of their receptor Pex5p to the cognate signal and to residues adjacent too it. J.Biol.Chem. 273: 33635-33643.
46.. Miura S., Kasuya-Arai I., Mori H., Miyazawa S., Osumi T., Hashimoto T. and Fujiki Y. (1992) Carboxyl-terminall consensus Ser-Lys-Leu-related tripeptide of peroxisomal proteins functions in vitro as a minimall peroxisome-targeting signal. J.Biol.Chem. 267:14405-14411.
47.. Subramani S., Koller A. and Snyder W.B. (2000) Import of peroxisomal matrix and membrane proteins.
Annu.Rev.Biochem.Annu.Rev.Biochem. 69: 399-418.
48.. Swinkels B.W., Gould S.J., Bodnar A.G., Rachubinski R.A. and Subramani S. (1991) A novel, cleavable peroxisomall targeting signal at the amino-terminus of the rat 3-ketoacyl-CoA thiolase. EMBO J. 10: 3255-3262. .
49.. Klein AT., Van den B.M., Bottger G., Tabak H.F. and Distel B. (2002) Saccharomyces cerevisiae acyl-CoAA oxidase follows a novel, non-PTSl, import pathway into peroxisomes that is dependent on Pex5p.
J.Biol.Chem.J.Biol.Chem. 277: 25011-25019.
50.. Dodt G., Braverman N., Wong C., Moser A., Moser H.W., Watkins P., Valle D. and Gould S.J. (1995) Mutationss in the PTS1 receptor gene, PXR1, define complementation group 2 of the peroxisome biogenesiss disorders. Nat.Genet. 9:115-125.
51.. Brocard C , Kragler F., Simon M.M., Schuster T. and Hartig A. (1994) The tetratricopeptide repeat-domainn of the PAS10 protein of Saccharomyces cerevisiae is essential for binding the peroxisomal targetingg signal-SKL. Biochem.Biophys.Rcs.Commun. 204: 1016-1022.
52.. Gatto G.J., Jr., Geisbrecht B.V., Gould S.J. and Berg J.M. (2000) Peroxisomal targeting signal-1 recognitionn by the TPR domains of human PEX5. Nal.Struct.Biol. 7: 1091-1095.
53.. Otera H., Setoguchi K., Hamasaki M., Kumashiro T., Shimizu N. and Fujiki Y. (2002) Peroxisomal targetingg signal receptor Pex5p interacts with cargoes and import machinery components in a spatiotemporallyy differentiated manner: conserved Pex5p WXXXF/Y motifs are critical for matrix proteinn import. Mol.Cell Biol. 22:1639-1655.
54.. Saidowsky J., Dodt G., Kirchberg K., Wegner A., Nastainczyk W., Kunau W.H. and Schliebs W. (2001) Thee di-aromatic pentapeptide repeats of the human peroxisome import receptor PEX5 are separate high
affinityy binding sites for the peroxisomal membrane protein PEX14. J.Biol.Chem. 276: 34524-34529. 55.. P u r d u e P.E., Yang X. and Lazarow P.B. (1998) Pexl8p and Pex21p, a novel pair of related peroxins
essentiall for peroxisomal targeting by the PTS2 pathway. J.Cell Biol. 143:1859-1869.
56.. Einwachter H., Sowinski S., Kunau W.H. and Schliebs W. (2001) Yarrowia lipolyrica Pex20p, Saccharomycess cerevisiae Pexl8p/Pex21p and mammalian PexSpL fulfil a common function in the early stepss of the peroxisomal PTS2 import pathway. EMBO Rep. 2: 1035-1039.
57.. Sichting M , Schell-Steven A., Prokisch H., Erdmann R. and Rottensteiner H. (2003) Pex7p and Pex20p of Neurosporaa crassa Function Together in PTS2-dependent Protein Import into Peroxisomes. Mol.Biol.Cell 14:810-821. .
58.. Dodt G., Warren D., Becker E., Rehling P. and Gould SJ. (2001) Domain mapping of human PEX5 revealss functional and structural similarities to Saccharomyces cerevisiae Pexl8p and Pex21p.
I.Biol.Chem.I.Biol.Chem. 276: 41769-41781.
59.. Otera H., harano t., Honsho M., Ghaedi K., Mukai S., Tanaka A., Kawai A., Shimizu N. and Fujiki Y. (2000)) The mammalian peroxin Pex5pL, the longer isoform of the mobile peroxisome targeting signal (PTS)) type 1 transporter, translocates the Pex7p.PTS2 protein complex into peroxisomes via its initial dockingg site, Pexl4p. J.Biol.Chem. 275: 21703-21714.
60.. Motley A.M., Hettema E.H., Hogenhout E.M., Brites P., ten Asbroek A.L., Wijburg F.A., Baas F., Heijmanss H.S., Tabak H.F., Wanders R.J. and Distel B. (1997) Rhizomelic chondrodysplasia punctata is a peroxisomall protein targeting disease caused by a non-functional PTS2 receptor. Nat.Genet. 15: 377-380. 61.. Holroyd C. and Erdmann R. (2001) Protein translocation machineries of peroxisomes. FEBS Lett. 501:
6-10. .
62.. Urquhart A.J., Kennedy D., Gould S.J. and Crane D.I. (2000) Interaction of Pex5p, the type 1 peroxisome targetingg signal receptor, with the peroxisomal membrane proteins Pexl4p and Pexl3p. J.Biol.Chem. 275: 4127-4136. .
63.. Liu Y., Bjorkman J., Urquhart A., Wanders R.J., Crane D.I. and Gould S.J. (1999) PEX13 is mutated in complementationn group 13 of the peroxisome-biogenesis disorders. Am.J.Hum.Genet. 65: 621-634, 64.. Smith J.J., Szilard R.K., Marelli M. and Rachubinski R.A. (1997) The peroxin Pexl7p of the yeast
Yarrowiaa lipolyrica is associated peripherally with the peroxisomal membrane and is required for the importt of a subset of matrix proteins. Mol.Cell Biol. 17: 2511-2520.
65.. Huhse B„ Rehling P., Albertini M., Blank L., Meller K. and Kunau W.H. (1998) Pexl7p of Saccharomyces cerevisiaee is a novel peroxin and component of the peroxisomal protein translocation machinery. J.Cell
Biol.Biol. 140: 49-60.
66.. Shimozawa N., Tsukamoto T., Suzuki Y., Orii T., Shirayoshi Y., Mori T. and Fujiki Y. (1992) A h u m a n genee responsible for Zellweger syndrome that affects peroxisome assembly. Science 255: 1132-1134. 67.. O k u m o t o K., Itoh Rv Shimozawa N., Suzuki Y., Tamura S., Kondo N. and Fujiki Y. (1998) Mutations in
PEX100 is the cause of Zellweger peroxisome deficiency syndrome of complementation group B.
Hum.Mol.Genet.Hum.Mol.Genet. 7:1399-1405.
68.. Warren D.S., Morrell J.C., Moser H.W., Valle D. and Gould S.J. (1998) Identification of PEX10, the gene defectivee in complementation group 7 of the peroxisome-biogenesis disorders. Am.J.Hum.Genet. 63: 347-359. .
69.. Chang C.C., Lee W.H., Moser H., Valle D. and Gould SJ. (1997) Isolation of the human PEX12 gene, mutatedd in g r o u p 3 of the peroxisome biogenesis disorders. Nat.Genet. 15: 385-388.
70.. Chang C.C., Warren D.S., Sacksteder K.A. and Gould SJ. (1999) PEX12 interacts with PEX5 and PEX10 andd acts downstream of receptor docking in peroxisomal matrix protein import. J.Cell Biol. 147: 761-774. 71.. O k u m o t o K., Abe I. and Fujiki Y. (2000) Molecular anatomy of the peroxin Pexl2p: ring finger domain is
essentiall for Pexl2p function and interacts with the peroxisome- targeting signal type 1-receptor Pex5p andd a ring peroxin, PexlOp. J.Biol.Chem. 275: 25700-25710.
72.. Albertini M., Girzalsky W., Veenhuis M. and Kunau W.H. (2001) Pexl2p of Saccharomyces cerevisiae is aa component of a multi-protein complex essential for peroxisomal matrix protein import. Eur.J.Cell Biol. 80:: 257-270.
73.. Reguenga C , Oliveira M.E., Gouveia A.M., Sa-Miranda C. and Azevedo J.E. (2001) Characterization of thee mammalian peroxisomal import machinery: Pex2p, Pex5p, Pexl2p, and Pexl4p are subunits of the samee protein assembly. J.Biol.Chem. 276: 29935-29942.
74.. W a t e r h a m H.R., Titorenko V.I., Haima P., Cregg J.M., Harder W. and Veenhuis M. (1994) The Hansenulaa polymorpha PERI gene is essential for peroxisome biogenesis and encodes a peroxisomal matrixx protein with both carboxy- and amino-terminal targeting signals. J.Cell Biol. 127: 737-749. 75.. Liu H., Tan X., Russell K.A., Veenhuis M. and Cregg J.M. (1995) PER3, a gene required for peroxisome
J.Biol.Chem.J.Biol.Chem. 270: 10940-10951.
76.. Rehling P., Skaletz-Rorowski A., Girzalsky W., Voorn-Brouwer T., Franse M.M., Distel B., Veenhuis M., Kunauu W.H. and Erdmann R. (2000) Pex8p, an intraperoxisomal peroxin of Saccharomyces cerevisiae requiredd for protein transport into peroxisomes binds the PTS1 receptor pex5p. J.Biol.Chem. 275: 3593-3602. .
77.. Agne B., Meindl N.M., Niederhoff K., Einwachter H., Rehling P., Sickmann A., Meyer H.E., Girzalsky W.. and Kunau W.H. (2003) Pex8p: an intraperoxisomal organizer of the peroxisomal import machinery.
Mol.CellMol.Cell 11: 635-646.
78.. Dodt G. and Gould SJ. (1996) Multiple PEX genes are required for proper subcellular distribution and stabilityy of Pex5p, the PTS1 receptor: evidence that PTS1 protein import is mediated by a cycling receptor.. J.Cell Biol. 135: 1763-1774.
79.. Dammai V. and Subramani S. (2001) The human peroxisomal targeting signal receptor, Pex5p, is translocatedd into the peroxisomal matrix and recycled to the cytosol. Celt. 105: 187-196.
80.. Reuber B.E., Germain-Lee E., Collins C.S., Morrell J.C., Ameritunga R., Moser H.W., Valle D. and Gould S.J.. (1997) Mutations in PEX1 are the most common cause of peroxisome biogenesis disorders. Nat.Genet.
17:: 445-448.
81.. Portsteffen H., Beyer A., Becker E., Epplen C , Pawlak A., Kunau W.H. and Dodt G. (1997) H u m a n PEX1 iss mutated in complementation group 1 of the peroxisome biogenesis disorders. Nat.Genet. 17: 449-452. 82.. Fukuda S., Shimozawa N., Suzuki Yv Zhang Z., Tomatsu S., Tsukamoto T., Hashiguchi N., Osumi T.,
Masunoo M., Imaizumi K., Kuroki Y., Fujiki Y., Orii T. and Kondo N. (1996) Human peroxisome assemblyy factor-2 (PAF-2): a gene responsible for group C peroxisome biogenesis disorder in humans.
Am.J.Hum.Genet.Am.J.Hum.Genet. 59:1210-1220.
83.. Faber K.N., Heyman J.A. and Subramani S. (1998) Two AAA family peroxins, PpPexlp and PpPex6p, interactt with each other in an ATP-dependent manner and are associated with different subcellular membranouss structures distinct from peroxisomes. Mol.Cell Biol. 18: 936-943.
84.. Yahraus T., Braverman N., Dodt G., Kalish J.E., Morrell J.C., Moser H.W., Valle D. and Gould S.J. (1996) Thee peroxisome biogenesis disorder group 4 gene, PXAAA1, encodes a cytoplasmic ATPase required forr stability of the PTS1 receptor. EMBO J. 15: 2914-2923.
85.. Kiel J.A., Hilbrands R.E., Van D.K., I, Rasmussen S.W., Salomons F.A., van der H.M., Faber K.N., Cregg J.M.. and Veenhuis M. (1999) Hansenula polymorpha Pexlp and Pex6p are peroxisome-associated AAA proteinss that functionally and physically interact. Yeast 15: 1059-1078.
86.. Tamura S., Okumoto K., Toyama R., Shimozawa N., Tsukamoto T., Suzuki Y., Osumi T., Kondo N. and Fujikii Y. (1998) Human PEX1 cloned by functional complementation on a CHO cell mutant is responsiblee for peroxisome-deficient Zellweger syndrome of complementation group I.
Proc.Natl.Acad.Sci.U.S.AProc.Natl.Acad.Sci.U.S.A 95: 4350-4355.
87.. Tsukamoto T., Miura S., Nakai T., Yokota S., Shimozawa N., Suzuki Y., Orii T., Fujiki Y., Sakai F., Bogaki A.. and . (1995) Peroxisome assembly factor-2, a putative ATPase cloned by functional complementation onn a peroxisome-deficient mammalian cell mutant. Nat.Genet. 11: 395-401.
88.. Spong A.P. and Subramani S. (1993) Cloning and characterization of PAS5: a gene required for peroxisomee biogenesis in the methylotrophic yeast Pichia pastoris. J.Cell Biol. 123: 535-548.
89.. Collins C.S., Kalish J.E., Morrell J.C., McCaffery J.M. and Gould S.J. (2000) The peroxisome biogenesis factorss pex4p, pex22p, pexlp, and pex6p act in the terminal steps of peroxisomal matrix protein import.
Mol.CellMol.Cell Biol. 20: 7516-7526.
90.. Patel S. and Latterich M. (1998) The AAA team: related ATPases with diverse functions. Trends Cell Biol. 8:65-71. .
91.. Birschmann I., Stroobants A.K., Van den B.M., Schafer A., Rosenkranz K., Kunau W.H. and Tabak H.F. (2003)) Pexl5p of Saccharomyces cerevisiae provides a molecular basis for recruitment of the AAA peroxinn Pex6p to peroxisomal membranes. Mol.Biol.Cell 14: 2226-2236.
92.. Matsumoto N., Tamura S. and Fujiki Y. (2003) The pathogenic peroxin Pex26p recruits the Pexlp-Pex6p AAAA ATPase complexes to peroxisomes. Nat.Cell Biol. 5: 454-460.
93.. Matsumoto N., Tamura S., Furuki S., Miyata N., Moser A., Shimozawa N., Moser H.W., Suzuki Y,, Kondoo N. and Fujiki Y. (2003) Mutations in novel peroxin gene PEX26 that cause peroxisome-biogenesis disorderss of complementation group 8 provide a genotype-phenotype correlation. Am.J.Hum.Genet. 73: 233-246. .
94.. Koller A., Snyder W.B., Faber K.N., Wenzel T.J., Rangell L., Keller G.A. and Subramani S. (1999) Pex22p off Pichia pastoris, essential for peroxisomal matrix protein import, anchors the ubiquitin-conjugating enzyme,, Pex4p, on the peroxisomal membrane. J.Cell Biol, lib: 99-112.
ubiquitin-conjugatingg enzymes. Nature, 359: 73-76.
96.. Erdmann R. and Blobel G. (1995) Giant peroxisomes in oleic acid-induced Saccharomyces cerevisiae lackingg the peroxisomal membrane protein Pmp27p. J.Cell Biol. 128: 509-523.
97.. Marshall P.A., Krimkevich Y.I., Lark R.H., Dyer J.M., Veenhuis M. and Goodman J.M. (1995) Pmp27 promotess peroxisomal proliferation. j.Cell Biol. 129: 345-355.
98.. Schrader M., Reuber B.E., Morrell J.C., Jimenez-Sanchez G., Obie C , Stroh T.A., Valle D., Schroer T.A. andd Gould S.J. (1998) Expression of PEXllbeta mediates peroxisome proliferation in the absence of extracellularr stimuli. J.Biol.Chem. 273: 29607-29614.
99.. van Roermund C.W., Tabak H.F., Van den B.M., Wanders R.J. and Hettema E.H. (2000) P e x l l p plays a primaryy role in medium-chain fatty acid oxidation, a process that affects peroxisome number and size in Saccharomycess cerevisiae. J.Cell Biol. 150:489-498. .
100.. Hoepfner D., Van den B.M., Philippsen P., Tabak H.F. and Hettema E.H. (2001) A role for Vpslp, actin, andd the Myo2p motor in peroxisome abundance and inheritance in Saccharomyces cerevisiae. J.Cell Biol. 155:: 979-990.
101.. Li X. and Gould S.J. (2003) The dynamin-like GTPase DLP1 is essential for peroxisome division and is recruitedd to peroxisomes in part by PEX11. J.Biol.Chem. 278: 17012-17020.
102.. Smith J.J., Marelli M., Christmas R.H., Vizeacoumar F J., Dilworth D.J., Ideker T., Galitski T., Dimitrov K.,, Rachubinski R.A. and Aitchison J.D. (2002) Transcriptome profiling to identify genes involved in peroxisomee assembly and function. J.Cell Biol. 158: 259-271.
103.. Tarn Y.Y., Torres-Guzman J.C., Vizeacoumar F.J., Smith J.J., Marelli Mv Aitchison J.D. and Rachubinski
R.A.. (2003) Pexll-related Proteins in Peroxisome Dynamics: A Role for the Novel Peroxin Pex27p in Controllingg Peroxisome Size and Number in Saccharomyces cerevisiae. Mol.Biol.Cell 14: 4089-4102. 104.. Rottensteiner H., Stein K., Sonnenhol E. and Erdmann R. (2003) Conserved function of p e x l l p and the
novell pex25p and pex27p in peroxisome biogenesis. Mol.Biol.Cell 14: 4316-4328.
105.. Vizeacoumar F.J., Torres-Guzman J.C., Tam Y.Y., Aitchison J.D. and Rachubinski R.A. (2003) YHR150w andd YDR479c encode peroxisomal integral membrane proteins involved in the regulation of peroxisome number,, size, and distribution in Saccharomyces cerevisiae. J.Cell Biol. 161: 321-332.
106.. Wanders R.J., Barth P.G. and Heymans H.S. (2001) Single peroxisomal enzyme deficiencies. In: Scriver C.R.,, Beaudet A.L., Valle D. and Sly W.S. (eds.) The metabolic and molecular bases of inherited disease. McGraw-Hill,, New York, 3219-3256.
107.. Ferdinandusse S., Denis S., Mooijer P.A., Zhang Z., Reddy J.K., Spector A.A. and Wanders R.J. (2001) Identificationn of the peroxisomal beta-oxidation enzymes involved in the biosynthesis of docosahexaenoicc acid. J.Lipid Res. 42: 1987-1995.
108.. Wanders R.J., Jansen G.A. and Lloyd M.D. (2003) Phytanic acid alpha-oxidation, new insights into an oldd problem: a review. Biochim.Biophys.Acta 1631: 119-135.
109.. Ginsberg L., Rafique S., Xuereb J.H., Rapoport S.I. and Gershfeld N.L. (1995) Disease and anatomic specificityy of ethanolamine plasmalogen deficiency in Alzheimer's disease brain. Brain Res. 698: 223-226. 110.. Kovacs W.J., Olivier L.M. and Krisans S.K. (2002) Central role of peroxisomes in isoprenoid
biosynthesis.. Pwg.Lipid Res. 41: 369-391.
111.. Hogenboom S., Romeijn G.J., Houten S.M., Baes M., Wanders R.J. and Waterham H.R. (2002) Absence of functionall peroxisomes does not lead to deficiency of enzymes involved in cholesterol biosynthesis.
J.LipidJ.Lipid Res. 43: 90-98.
112.. Hogenboom S. (2003) Subcellular localization of the h u m a n isoprenoid biosynthesis pathway. Thesis 113.. Ulrich J., Herschkowitz N., Heitz P., Sigrist T. and Baerlocher P. (1978) Adrenoleukodystrophy.
Preliminaryy report of a connatal case. Light- and electron microscopical, immunohistochemical and biochemicall findings. Acta Neuropathol.(Berl) 43: 77-83.
114.. Kelley R.I., Datta N.S., Dobyns W.B., Hajra A.K., Moser A.B., Noetzel M.J., Zackai E.H. and Moser H.W. (1986)) Neonatal adrenoleukodystrophy: new cases, biochemical studies, and differentiation from Zellwegerr and related peroxisomal polydystrophy syndromes. Am.J.Med.Genet. 23: 869-901.
115.. Scotto J.M., Hadchouel M., Odievre M., Laudat M.H., Saudubray J.M., Dulac O., Beucler I. and Beaune P.. (1982) Infantile phytanic acid storage disease, a possible variant of Refsum's disease: three cases, includingg ultrastructural studies of the liver. J.Inherit.Metab Dis. 5: 83-90.
116.. Poulos A., Sharp P. and Whiting M. (1984) Infantile Refsum's disease (phytanic acid storage disease): a variantt of Zellweger's syndrome? Clin.Genet. 26: 579-586.
117.. Ogier H., Roels F., Comelis A., Poll The BT, Scotto J.M., Odievre M. and Sandubray J.M. (1985) Absence off hepatic peroxisomes in a case of infantile Refsum's disease. Scand.J.Clin.Lab Invest 45: 767-768. 118.. Wanders RJ, Barth PG, Schutgens RB and Heymans HS (1996) Peroxisomal disorders: Post- and prenatal
119.. Brul S., Westerveld A., Strijland A., Wanders R.J., Schram A.W., Heymans H.S., Schutgens R.B., van den B.H.. and Tager J.M. (1988) Genetic heterogeneity in the cerebrohepatorenal (Zellweger) syndrome and otherr inherited disorders with a generalized impairment of peroxisomal functions. A study using complementationn analysis. J.Clin.Invest 81:1710-1715.
120.. Gould S.J. and Valle D. (2000) Peroxisome biogenesis disorders: genetics and cell biology. Trends Genet. 16:: 340-345.
121.. Geisbrecht B.V., Collins C.S., Reuber B.E. and Gould S.J. (1998) Disruption of a PEX1-PEX6 interaction is thee most common cause of the neurologic disorders Zellweger syndrome, neonatal adrenoleukodystrophy,, and infantile Refsum disease. Proc.Natl.Acad.Sci.U.S.A 95: 8630-8635.
122.. Collins C.S. and Gould S.J. (1999) Identification of a common PEX1 mutation in Zellweger syndrome.
Hum.Mutat.Hum.Mutat. 14: 45-53.
123.. Imamura A., Tamura S., Shimozawa N., Suzuki Y., Zhang Z., Tsukamoto T., Orii T., Kondo N., Osumi T. andd Fujiki Y. (1998) Temperature-sensitive mutation in PEX1 moderates the phenotypes of peroxisome deficiencyy disorders. Hum.Mol.Genet. 7: 2089-2094.
124.. Gartner ]., Preuss N., Brosius U. and Biermanns M. (1999) Mutations in PEX1 in peroxisome biogenesis disorders:: G843D and a mild clinical phenotype. J.lnherit.Metab Dis. 22: 311-313.
125.. Maxwell M.A., Nelson P.V., Chin S.J., Paton B.C., Carey W.F. and Crane D.I. (1999) A common PEX1 frameshiftt mutation in patients with disorders of peroxisome biogenesis correlates with the severe Zellwegerr syndrome phenotype. Hum.Genet. 105: 38-44.
126.. Walter C , Gootjes J., Mooijer P.A., Portsteffen H., Klein C , Waterham H.R., Barth P.G., Epplen J.T., Kunauu W.H., Wanders R.J. and Dodt G. (2001) Disorders of peroxisome biogenesis due to mutations in PEX1:: phenotypes and PEX1 protein levels. Am.J.Hum.Genet. 69: 35-48.
127.. Shimozawa N., Nagase T., Takemoto Y., Ohura T., Suzuki Y. and Kondo N. (2003) Genetic heterogeneity off peroxisome biogenesis disorders among Japanese patients: Evidence for a founder haplotype for the mostt common PEX10 gene mutation. Am.J.Med.Genet. 120A: 40-43.
128.. Imamura A., Tsukamoto T., Shimozawa N., Suzuki Y., Zhang Z., Imanaka T., Fujiki Y., Orii T., Kondo N.. and Osumi T. (1998) Temperature-sensitive phenotypes of peroxisome-assembly processes represent thee milder forms of human peroxisome-biogenesis disorders. Am.].Hum.Genet. 62:1539-1543.
129.. Imamura A., Shimozawa N., Suzuki Y., Zhang Z., Tsukamoto T., Fujiki Y., Orii T., Osumi T., Wanders RJ.. and Kondo N. (2000) Temperature-sensitive mutation of PEX6 in peroxisome biogenesis disorders inn complementation group C (CG-C): comparative study of PEX6 and PEX1. Pediatr.Res. 48: 541-545. 130.. Imamura A., Shimozawa N., Suzuki Y., Zhang Z., Tsukamoto Tv Orii T., Osumi T. and Kondo N. (2001)
Temperaturee sensitive acyl-CoA oxidase import in group A peroxisome biogenesis disorders.
J.Med.Genet.J.Med.Genet. 38: 871-874.
131.. Shimozawa N., Suzuki Y., Zhang Z., Imamura A., Toyama R., Mukai S., Fujiki Y., Tsukamoto T., Osumi T.,, Orii Tv Wanders R.J. and Kondo N. (1999) Nonsense and temperature-sensitive mutations in PEX13
aree the cause of complementation group H of peroxisome biogenesis disorders. Hum.Mol.Genet. 8: 1077-1083. .
132.. Wilson G.N., Holmes R.G., Custer J., Lipkowitz J.L., Stover J., Datta N. and Hajra A. (1986) Zellweger syndrome:: diagnostic assays, syndrome delineation, and potential therapy. Am.J.Med.Genet. 24: 69-82. 133.. Moser A.B., Borel J., Odone A., Naidu S., Cornblath D., Sanders D.B. and Moser H.W. (1987) A new
dietaryy therapy for adrenoleukodystrophy: biochemical and preliminary clinical results in 36 patients.
Ann.Neurol.Ann.Neurol. 21: 240-249.
134.. Setchell K.D., Bragetti P., Zimmer-Nechemias L., Daugherty C , Pelli M.A., Vaccaro R., Gentili G., Distruttii E., Dozzini G., Morelli A. and . (1992) Oral bile acid treatment and the patient with Zellweger syndrome.. Hematology 15: 198-207.
135.. Martinez M. (2001) Restoring the DHA levels in the brains of Zellweger patients. J.Mol.Neuwsci. 16: 309-316. .
136.. Martinez M. and Vazquez E. (1998) MR1 evidence that docosahexaenoic acid ethyl ester improves myelinationn in generalized peroxisomal disorders. Neurology 51: 26-32.
137.. Lazarow P.B., Black V„ Shio H., Fujiki Y., Hajra A.K., Datta N.S., Bangaru B.S. and Dancis J. (1985) Zellwegerr syndrome: biochemical and morphological studies on two patients treated with clofibrate.
Pediatr.Res.Pediatr.Res. 19:1356-1364.
138.. Bjorkhem I., Blomstrand S., Glaumann H. and Strandvik B. (1985) Unsuccessful attempts to induce peroxisomess in two cases of Zellweger disease by treatment with clofibrate. Pediatr.Res. 19: 590-593. 139.. Wei H., Kemp S., McGuinness M.C., Moser A.B. and Smith K.D. (2000) Pharmacological induction of
