University of Groningen
Cellular Stress in Aging and Cancer
Sturmlechner, Ines
DOI:
10.33612/diss.170212168
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Publication date:
2021
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Citation for published version (APA):
Sturmlechner, I. (2021). Cellular Stress in Aging and Cancer. University of Groningen.
https://doi.org/10.33612/diss.170212168
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Summary
Nederlandse samenvatting
Acknowledgements
List of publications
Curriculum vitae
Summary
Chronic cellular damage and stress are strongly implicated in various pathologies and diseases. However, due to the variety and complexity of stresses and stress responses, it is not fully understood how the fate of cells and organisms is determined by specific stresses. In this thesis, we focus on two major aspects of disease-relevant chronic stress: cellular senescence & aging and aneuploidy & cancer development. We aim to better understand not only their molecular signatures but also their physiological consequences using experimental mouse models.
The first part of this thesis, described in chapters 2, 3, 4, 5 and 6, illuminates cellular senescence and its properties as outcome of stresses during organismal aging or diseases. Additionally, we investigate cellular senescence due to cellular stresses at the end of the cell’s replicative lifespan, during DNA damage, as well as due to hyperactive oncogenes.
Specifically, in chapter 5, we revealed P21 as one of few genes that is commonly epigenetically and transcriptionally activated during many of these senescence-inducing stresses in vitro and in vivo. By using a combination of bioinformatic approaches, cell culture experiments and generation of new transgenic mouse models, we elucidated P21’s previously unrecognized role in promoting a bioactive secretome of stressed and senescent cells. This mechanism was dependent on Retinoblastoma protein (RB) and select transcription factors of the STAT and SMAD family with which RB interacted to promote their activity. The resultant secretome, termed P21-activated secretory phenotype (PASP), recruited immune cells, first and foremost macrophages, and eventually lead to target cell elimination by T lymphocytes. We conclude that P21 and its non-cell-autonomous function places stressed and senescent cells under immunosurveillance. Therefore, P21 not only promotes cell cycle arrest to prevent propagation of stressed, potentially preneoplastic cells, but also stimulates immune cell mediated clearance mechanisms to permanently neutralize such cells.
During the last decade, cellular senescence has increasingly emerged as disease-relevant cell fate and has drawn attention as potential therapeutic target for many diseases, including Alzheimer’s Disease, atherosclerosis, osteoarthritis, liver diseases and others. Our study presents not only novel therapeutic opportunities to facilitate immune system mediated cell elimination of senescent cells but also raises caution on applying existing senomorphic strategies (approaches to modulate properties of senescent cells) that aim to broadly restrain the secretome of senescent cells.
In the second part of this thesis, we focus on the molecular and physiological consequences of aneuploidy-causing stresses due to perturbation of cell cycle regulators. In the studies described in chapters 6, 7 and 8, we employ molecular techniques and novel experimental mouse models to decipher the physiological impact of BUBR1, CCNE1 and FOXM1 function on aneuploidy and tumorigenesis.
In chapter 6, we studied BUBR1 (BUB1B) allelic effects on the type and severity of cancer and progeroid phenotypes. We found that BUBR1 protein levels alone did not determine phenotypic severity. The type of BUB1B allele mutation also significantly influenced cellular and physiological phenotypes, such as aneuploidy rates, type of chromosome segregation errors, characteristics of senescent cells, tumor growth, lifespan and health span. Our results help explain the phenotypic heterogeneity of patients with mosaic variegated aneuploidy (MVA), a rare human syndrome caused by genetic perturbations in BUB1B,
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In chapter 7, we revealed that CCNE1 overexpression causes a multitude of cellular phenotypes including aneuploidy and provoke tumor development specifically in the liver of mice. In vitro we found that overexpression of CCNE1 perturbs cell cycle timing, leads to DNA damage, chromosome missegregation and aneuploidy. Chromosome segregation errors and aneuploidy were also detected in some, but not all, tissues of CCNE1-overexpressing mice. While liver, lung and kidney contained increased amounts of aneuploid cells, the liver additionally exhibited higher levels of oxidative stress, P53 activation and immune system changes which may collectively cause development of hepatocellular carcinoma (HCC). Importantly, the CCNE1 locus is amplified in various types of human cancers and is activated in HCC patients infected with hepatitis B virus or adeno-associated virus type 2 due to integration of the virus near the CCNE1 locus. Our studies therefore indicate that CCNE1 overexpression drives aneuploidy and liver tumor development.
Chapter 8 reports on the mechanism by which FOXM1 protects against chromosome missegregation, aneuploidy and tumor development in mice. Foxm1 deficient mice exhibited increased aneuploidy rates and spontaneous tumor development and were susceptible to oncogene-mediated lung or colon/small-intestinal tumor formation. Using Foxm1 deficient cells in culture we revealed the molecular pathway by which FOXM1 ensures mitotic fidelity and protects against aneuploidy. Foxm1 mutant cells exhibited centrosome movement defects, asymmetric spindles, chromosome segregation errors causing aneuploidy and chromosomal instability (CIN). We found that FOXM1 protects against these phenotypes by binding and constraining ECT2 and thereby restricting RhoA signaling. If FOXM1 levels were low or absent, RhoA signaling becames hyperactive causing hyper-nucleation of cortical actin during mitosis and consequently asymmetric spindle formation and aneuploidy. Intriguingly, we found that the N-terminus is the portion of FOXM1 that mediates ECT2 inhibition, and overexpression of the FOXM1 N-terminus not only normalized chromosome missegregation and aneuploidy in cells and tissues of Foxm1 deficient mice but also in Foxm1 wildtype mice in the MMTV-PyVT lung and breast tumor model. These results suggest that the FOXM1 N-terminus could be useful as broadly applicable, novel anti-cancer peptide to promote mitotic fidelity and stabilize aneuploidy levels.
In conclusion, this thesis highlights the complexity of stress responses and resultant cell fates. Many stresses can cause cellular senescence, which can have beneficial and detrimental consequences on tissues and organs depending on the stressor, cell type and spatio-temporal factors. We provide novel insights into the mechanisms by which stressed cells and senescent cells communicate with and are being cleared by immune cells. Our studies on P21 suggest that already in the early stages of stress responses cells not only adapt cell intrinsic functions (such as induction of cell cycle arrest) to counteract cellular transformation, but also induce cell non-autonomous mechanisms to alarm immune cells. P21’s role in cell cycle control and immunosurveillance could therefore be leveraged to develop safe, novel senomorphic and senotherapeutic strategies. Such avenues could aid in neutralizing detrimental senescent cells that arise during aging or drive various age-related diseases. Additionally, our studies present a basis to explore experimental therapies to encourage neutralization of stressed, non-senescent cells during early stages of relevant disease contexts or even before disease onset. Similarly, our studies on stresses due to perturbations in the cell cycle machinery that cause aneuploidy and tumor development, may be useful in developing novel avenues to stabilize chromosomal instability. While many questions remain on aneuploidy and its physiological consequences, we elucidate how perturbation in specific cell cycle regulators can cause aneuploidy and/or tumor or progeroid phenotypes in mice. Importantly, we identify the FOXM1 N-terminus as an anti-aneuploidy agent that protects against tumor development. Hence, our studies provide proof-of-principle that stabilizing CIN is a viable anti-cancer strategy that could be leveraged for treatment of a variety of tumors.
Nederlandse samenvatting
Chronische cellulaire schade en stress zijn sterk betrokken bij het optreden van ziekte. Vanwege de variëteit en complexiteit van stress en stress responsen blijft het echter onduidelijk hoe dit cellen en organismen beïnvloedt. Dit proefschrift richt zich op twee belangrijke aspecten van ziekte-gerelateerde chronische stress, namelijk cellulaire veroudering alsmede de rol van chromosoominstabiliteit, en in het bijzonder aneuploïdie in de ontwikkeling van kanker. Daarbij streeft dit proefschrift zowel bij te dragen middels nieuwe inzichten over de moleculaire handtekening alsmede de fysiologische gevolgen van stress. Het eerste deel van dit proefschrift (hoofdstuk 2-6) richt zich op cellulaire veroudering en zijn specifieke eigenschappen ten gevolge van veroudering of ziekte in organismen. Daarnaast bekijkt het ook het effect van cellulaire stress aan het einde van de cel zijn levensduur ten gevolge van DNA schade en hyperactieve oncogenenen.
Hoofdstuk 5 richt zich in het bijzonder op de ontdekking van een nieuw gen dat zowel epigenetisch als transcriptioneel geactiveerd kan worden in verouderings-geïnduceerde stress in vitro en in vivo. Dit gen, genaamd P21 in staat is een bioactief secretoom te vormen door aan Retinoblasoma eiwit (RB) te binden. Dit RB-gebonden secretoom, ook wel P21-geactiveerd secretorisch fenotype (PASP) genoemd, zorgt vervolgens voor activatie van het immuunrespons (in het bijzonder macrofagen) en uiteindelijk voor doelgerichte cel-uitschakeling door T-lymfocyten. P21 bezit tezamen met zijn niet-cel-autonome functie dus over de mogelijkheid om gestreste en verouderde cellen onder immunosurveillance plaatsen. P21 heeft hierdoor de mogelijkheid om de celcyclus en voortplanting van gestreste, mogelijke pre-neoplastische, cellen te voorkomen, en stimuleert daarnaast het immuun gemedieerde klaringsmechanismen om gestreste en verouderde cellen te neutraliseren. Het remmen van cellulaire veroudering heeft het laatste decennia in toenemende mate aandacht gekregen, in het bijzonder als potentieel therapeutisch doelwit voor ziektes zoals Morbus Alzheimer, atherosclerose, osteoartritis, leverziekten en nog vele andere. Deze studie presenteert niet alleen nieuwe therapeutische mogelijkheden om immuun gemedieerde cel verwijdering van oude en gestreste cellen te vergemakkelijken, maar toont ook aan dat voorzichtigheid is geboden van het toepassen van bestaande senomorfe strategieën (modulatie van eigenschappen van verouderde cellen) die aangrijpen op het secretoom van verouderde cellen.
Het tweede deel van dit proefschrift richt zich op de moleculaire en fysiologische gevolgen van de aneuploïdie-veroorzaakte stressoren ten gevolge van verstoring van de cel-cyclus. In hoofdstuk 6,7 en 8, presenteren wij verscheidende moleculaire technieken en experimentele muismodellen om de fysiologische betekenis van BUBR1, CCNE1 en FOXM1 op aneuploïdie en tumorgenesis te ontcijferen.
In hoofdstuk 6 hebben we effect van allelmutatie van BUBR1 (BUB1B) op de ontwikkeling van type en ernst van kanker bestudeerd. Het blijkt dat alleen eiwitniveau van BUBR1 niet bepalend is voor de ernst van het fenotype, maar dat ook de soort BUB1B allel mutatie op belangrijke wijze cellulaire en fysiologische fenotypes beïnvloedt, zoals mate van aneuploïdie, type chromosoom-segregatiefouten, karakteristieken van verouderde cellen, tumorgroei, levensduur en gezonde levensduur. Deze resultaten helpen bij het verklaren van de fenotypische heterogeniteit van patiënten met mozaïek-bonte aneuploïdie (MVA), een zeldzaam menselijk syndroom veroorzaakt door genetische verstoringen in BUB1B, CEP57 of TRIP13.
In hoofdstuk 7 hebben we onthuld dat overexpressie van CCNE1 een veelvoud aan cellulaire fenotypes veroorzaakt, waaronder aneuploïdie, en dat het betrokken is bij de ontwikkeling van levertumoren in muizen. Overexpressie van CCNE1 blijkt in vitro de timing van de celcyclus te verstoren, en leidt tot
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schade, chromosoom-missegregatie en aneuploïdie. Chromosoom-segregatiefouten en aneuploïdie werden ook gedetecteerd in sommige, maar niet alle, weefsels van muizen met CCNE1-overexpressie. CCNE-1 overexpressie leidt tot toename van aneuplöide cellen in lever, long en nieren, waarbij de lever ook hogere niveaus van oxidatieve stress, P53-activering en veranderingen in het immuunsysteem vertoonde die gezamenlijk de ontwikkeling van hepatocellulair carcinoom (HCC) kunnen veroorzaken. Dit is van bijzonder belang gezien virale infecties (zoals hepatitus-B en adenogeassocieerd virus type 2) kunnen leiden tot virus-integratie nabij de CCNE1-locus om op deze manier bij te dragen tot tumorgroei. We concluderen dan ook dat overexpressie van CCNE1 de aneuploïdie en de ontwikkeling van levertumoren stimuleert.
Hoofdstuk 8 beschrijft het mechanisme waarmee FOXM1 beschermt tegen chromosoom missegregatie, aneuploïdie en tumorontwikkeling in muizen. Foxm1-deficiënte muizen vertonen verhoogde aneuploïdie en spontane tumorontwikkeling en zijn vatbaar voor toegenomen oncogen-gemedieerde long- of colon/dunne-intestinale tumorvorming. Op moleculair niveau blijkt FOXM1 belangrijk in bescherming van mitose en beschermt het tegen aneuploïdie. Foxm1-mutante cellen vertonen toegenomen aneuploïdie en chromosomale instabiliteit (CIN) ten gevolge van centrosoombewegingsdefecten, asymmetrische spindels en chromosoomsegregatiefouten. FOXM1 beschermt tegen deze fenotypes door binding van ECT2, dat leidt tot beperkte RhoA-signalering. Verminderding of afwezigheid van FOXM1-niveaus resulteert in toegenomen RhoA-signalering met hypernucleatie van corticaal actine tijdens mitose en daardoor asymmetrische spilvorming en aneuploïdie. Intrigerend genoeg blijkt de N-terminus het bepalende deel van FOXM1 is in ECT2-remming: overexpressie van de FOXM1 N-terminus normaliseert niet alleen chromosoommisegregatie en aneuploïdie in cellen en weefsels van Foxm1-deficiënte muizen, maar reduceert dit ook in cellen en weefsels van Foxm1-wildtype-muizen in het MMTV-PyVT-long- en borsttumormodel. Dit suggereert dat in FOXM1 N-terminus een mogelijk nieuwe en breed toepasbare antikanker peptide schuilt om mitotische betrouwbaarheid te bevorderen en aneuploïdie te stabiliseren.
Al met al benadrukt dit proefschrift de complexiteit van stressreacties en het daaruit voortvloeiende lot van cellen. Vele stressoren kunnen cellulaire veroudering veroorzaken, met zowel gunstige als nadelige gevolgen voor weefsels en organen, afhankelijk van stressfactor, celtype en spatio-temporele factoren. Dit proefschrift biedt nieuwe inzichten in de interactie mechanismen tussen immuuncellen en gestreste en verouderde cellen. Onze studies over P21 suggereren dat cellen al in de vroege stadia van stressreacties hun intrinsieke functies van cellen aanpassen (zoals inductie van celcyclusstop) om cellulaire transformatie tegen te gaan, maar dat ze daarnaast ook niet-autonome mechanismen van cellen activeren om immuuncellen te alarmeren. De rol van P21 in celcycluscontrole en immunosurveillance zou daarom kunnen worden gebruikt om veilige, nieuwe senomorfe en senotherapeutische strategieën te ontwikkelen. Dergelijke wegen zouden kunnen helpen bij het neutraliseren van schadelijke verouderde cellen of in leeftijd-gemedieerde ziekte. Daarnaast bieden onze studies een basis om experimentele therapieën te onderzoeken om de neutralisatie van gestreste, niet-verouderde cellen aan te moedigen tijdens vroege stadia van ziekte of zelfs vóór het begin van de ziekte. Evenzo kunnen onze onderzoeken naar aneuploïdie en tumorontwikkeling die het gevolg zijn van verstoring in de celcyclusmachine, nuttig zijn bij het ontwikkelen van nieuwe manieren om chromosomale instabiliteit te stabiliseren. Hoewel er nog veel vragen zijn over aneuploïdie en de fysiologische gevolgen ervan, leggen we in dit proefschrift uit hoe verstoring in specifieke celcyclusregelaars aneuploïdie en/of tumor- of progeroïde fenotypes bij muizen kan veroorzaken. Belangrijk is dat we de FOXM1 N-terminus identificeren als een anti-aneuploïdie middel dat beschermt tegen tumorontwikkeling. Daarom leveren onze studies het bewijs van het principe dat het stabiliseren van CIN een levensvatbare antikankerstrategie is die kan worden gebruikt voor de behandeling van een verscheidenheid aan tumoren.
Acknowledgements
When I was deciding to pursue a PhD, I told myself that „going for a PhD will not be easy, and it is not
supposed to be easy“. Indeed the past ~6 years have proven to be „not easy“. Despite hardships, I see
myself as very fortunate to have been able to grow and learn so much in a variety of aspects: scientifically, personally and inter-personally, as well as politically.
My PhD journey started with Prof. Dr. Jan van Deursen and Prof. Dr. Marten Hofker, who I owe the opportunity to conduct research at Mayo Clinic (USA) while simultaneously pursuing my PhD degree at the University of Groningen. I have been deeply grateful for this opportunity.
I have gotten to know Jan as a unique scientist in multiple ways. He has provided most, if not all, lab members with an exceptional amount of his time, with one-on-one or group meetings on a daily basis or even multiple times a day. I’m very grateful for Jan’s time investment and dedication to science, for I believe that due to this, I was able to learn a lot during my time in his lab. I’m thankful also to his extraordinary scientific writing and presentation skills that he instilled in me. I recognize the importance of clear and concise science communication and I see it as an important skill for my future career. I thank Jan also for all scientific opportunities that he provided, and the unique environment with brilliant lab members, very helpful collaborators and possibilities to pursue science on multiple levels (in cells, with newly generated mouse models and bioinformatically). Working with Jan and the experiences in his lab have clearly made me a better scientist!
I’m grateful to Marten to provide me with the PhD program opportunity and connection to the University of Groningen. I was saddened to hear of his sudden passing in 2016 and I know he will be greatly missed! I was very fortunate, that Prof. Dr. Bart van de Sluis was willing to step in as my PhD supervisor from Groningen’s side. I’m deeply grateful for his time and scientific input throughout the years, and for his priceless support, advice and help during preparation of this thesis. Bart’s qualities as PhD supervisor, advisor, supporter and mentor are exceptional and are qualities that I aspire to acquire myself! I count myself very lucky to have gotten to know him and cannot express my gratitude to him enough.
I was also very fortunate, that Prof. Dr. Bruce Horazdovsky was willing to step in as my other PhD supervisor from Mayo Clinic’s side after Jan’s retirement. I’m very thankful to Bruce, his time and availability for any questions, and his positive and professional attitude. “Always take the high road” is one of his mottos that I will always remember and try to act by as best as I can.
I’d also like to express my heartfelt thanks to the PhD thesis reading committee: Prof. Dr. Folkert Kuipers, Prof. Dr. Gerald de Haan and Prof. Dr. Niels Riksen!
During my PhD journey, I was fortunate to get to know and work with many people: excellent collaborators, encouraging co-authors, talented colleagues, bright trainees and magnificent friends.
I’m thankful to Prof. Dr. Darren Baker. He has provided help and advice throughout the years, starting with hands-on advice on cell culture, over scientific input during shared lab meetings, to being instrumental during the revision of my P21 manuscript. Particularly in the past year, I’m very grateful to him as he has spent lots of his time and effort on mediating between various parties during the lab transition, and I believe that without his effort, my manuscript revision would not have been possible.
I’m grateful to Prof. Dr. Hu Li and his lab for being extremely helpful collaborators and for sharing their bioinformatic skills with me and others. A variety of projects in the lab have greatly benefited from their contribution and help. Thank you to Hu for his time and help throughout the years! He has been encouraging and optimistic about projects and was always willing to try out multiple approaches to tackle scientific questions.
I’m deeply thankful to Dr. Chris Ross a previous member of the Li lab, with whom I worked with for 2 years to establish the ChIP-seq-based super enhancer identification pipeline. He has spent a tremendous amount of work on this analysis, we went through countless approaches of analyses and eventually we were successful to build a basis for our study of super enhancers in senescent cells. Thank you to Dr. Edroaldo Lummertz da Rocha for helping with the initial RNA-seq analysis in the lab! I’m very thankful to Dr. Cheng Zhang who provided his bioinformatic skills after Chris and Edroaldo. He has contributed to many projects in the lab with RNA-seq or scRNA-seq analyses. Throughout the years, the lab has asked a lot from him and I’m impressed how well and quickly he has implemented new approaches and provided us with high-quality analyses.
A big thank you also to Prof. Dr. Tamas Ordog and Dr. Jeong-Heon Lee from the Epigenomics Development Laboratory and Recharge Center (EDL) of the Center for Individualized Medicine at Mayo Clinic. Thanks to them, we were able to obtain high quality ChIP-seq data from flow-sorted senescent cells, a task that has been very tricky due to technical challenges. Without their expertise, the super enhancer project would not have been possible. Also, I’d like to acknowledge Dr. Jian Zhong from the EDL (who is also a former colleague from the van Deursen lab) for his advice on ChIP-PCR!
Prof. Dr. Virginia Shapiro and David Friedman from her lab were also fantastic collaborators, that I have been appreciating very much! Their expertise in immunology, macrophages and T cells was instrumental in shaping and interpreting the P21 manuscript story. As immunology has been mostly outside my own expertise, I have been very grateful for their time, help and support! I have not only learned a lot from them, but thanks to them I also discovered the excitement for immunology for myself!
I would like to collectively thank all additional co-authors and colleagues who contributed to the P21 manuscript and other publications that have been published or are in the works!
Thank you to Dr. Karthik Jeganathan, a dear colleague and friend, supervisor, lab manager, and master of western blot and immunoprecipitation! His amazing technical skills and contributions were very important to my projects, and his inter-personal skills and diplomatic approaches were crucial for many aspects of my time in the lab. I’m grateful for all his scientific and non-scientific support and advice!
Thank you to Dr. Naomi Hamada, also a dear colleague and friend, and wonderful role model! Naomi together with Dr. Cynthia Sieben have spent considerable time to train me in mouse work and organization, an aspect that I had very little knowledge of when starting in the lab. Naomi and I have spent an incredible amount of time to work together and help on each other’s projects (often well beyond midnight) and I couldn’t have asked for a better colleague and trainer. Naomi is probably the most well-organized person that I have ever met, and I feel very lucky to have gotten to know her and learned from her! Thank you for everything, Naomi-sensei!
Thank you also to Drs. Masakazu Hamada (Hamady) and Do Young Lim, also dear colleagues from the Transgenic and Knockout Core at Mayo Clinic! I’m very grateful to Hamady for sharing his molecular cloning expertise and for designing and/or generating 4 knockout and 1 transgenic mouse models for my projects, as well as multiple other mouse models for the lab that I also benefitted from! Similarly, I thank Do Young for her work and time generating these mouse models, as well as additional help to validate these models, something that was way beyond the typical core services. I have gotten to know her as
Appendices
somebody to always go above and beyond for colleagues, costumers and friends. She has been an amazing colleague and friend and I’m very lucky to have gotten to know her!
One big part of my PhD journey on which I will look back fondly, was the interaction and teamwork with colleagues and trainees. While being a PhD student myself, I was simultaneously training and guiding new lab members from various backgrounds, from high school students, to junior or senior college students, junior graduate students up to even a visiting scholar. I have counted 10 trainees that I have had between 2015 to 2019, with up to 4 of them simultaneously. Throughout my scientific career, I have learned that training people well is one of the most crucial steps to foster not only scientific and technical knowledge, but also excitement for science that may last a lifetime. Therefore, I have tried to the best of my abilities to spend as much knowledge, time, patience and understanding towards my trainees as possible. I wish them all lots of success, luck and happiness wherever they may go!
Thank you to my trainees who are co-authors on the P21 manuscript: Chance Sine, Erik-Jan van Deursen, Jan Grasic, Jeremy Stutchman and Ismail Can! They have either spent lots of time cloning and testing shRNAs for the super enhancer project, validated super enhancer-associated genes or generated valuable mouse models. It has been a pleasure to work with such bright, excited minds and the interaction with them in turn boosted my excitement and motivation towards science and education! Thank you for all your contributions. You all have very bright futures ahead!
In particular, I want to point out Chance’s contribution: he has spent three consecutive summers in the lab starting when still in high school. He first came to the lab with little to no technical knowledge, but his quick learning skills, excitement and hard work (often way beyond midnight) stood out and he soon became an efficient and independent colleague in the lab. I have been very impressed by him and I’m excited that he is contemplating to pursue a career in science, where I’m sure that he will excel!
EJ and Jeremy have similarly proven to be excited, intelligent and driven, and I’m thankful for their contributions to my project! They both are very sharp young minds and I have no doubt that they will excel in anything they set their minds on. Also, thank you EJ, for broadening my music horizon towards rap!
I thank Jan Grasic for his hard work and commitment in the lab! Working with him was lots of fun and he made the long hours in the lab more exciting. His work on generating mouse models for the lab were very valuable to me and others. I’m very excited that he is pursuing a PhD in science and wish him all the very best for the future!
Thank you to Raul Fierro Velasco, initially a trainee, who then became a great colleague and mouse manager for the lab! It has been a pleasure to train or advise him on various aspects throughout the years and, in turn, I thank him for contributing to my studies. I’m thankful for all his help on paraffin sectioning and mouse sacrifices and tissue collection. His contributions have helped me greatly throughout the years and particularly during manuscript revision times!
Thank you to Martina Gluscevic - first friend, then trainee, then colleague! It has been wonderful to watch her grow over the years and become a successful, independent thinker and worker. Martina has proven that she is very strong and intelligent, and she has, without a doubt, a very bright future ahead!
Thank you to Dr. Xuerong (Jonathan) Sun, a visiting scholar from China, who I had the pleasure of training and working with! His drive, commitment and excitement were astounding! I’m grateful for his scientific contributions to various projects in the lab. Besides him being a successful scientist, I also got to know him as wonderful and funny person. Again, thank you for the chocolates and ducks!
Thank you also to Ray Zhang, my very first trainee, for his work on the initial super enhancer studies. Thank you to Shaheen Kurani, a Mayo Clinic graduate student who was considering joining the lab.
Thank you so much to all the yet-unmentioned colleagues and co-authors of publications that I was able to contribute to!
I’m very grateful to Prof. Dr. Janine Kruit and her lab for giving me the opportunity to contribute to the Current Opinions in Lipidology review.
Thank you to all authors involved in the CCNE1 story, particularly first co-first author Dr. Khaled Aziz! It has been a pleasure working with him throughout our shared time in the lab. I was constantly impressed by his broad scientific and medical knowledge, and how he applied it to basic science projects. Similarly, I was often fascinated by his calm demeanor even in high stress situations, which rightly earned him the epithet “cool as a cucumber”.
Thank you to all authors involved in the BUBR1L1002P story, particularly first author Dr. Cynthia Sieben! As
mentioned above, she has been an amazing trainer, colleague and dear friend throughout the years and I’m eternally grateful for everything I learned from her. I immensely appreciate all the late-night “therapy” sessions and her continuous words of encouragement and support. Cynthia’s kindness and compassion know no equal. I’m convinced that without her, I would not have come this far. There are not enough words to express my gratitude!
Thank you to all authors involved in the FOXM1 story, particularly first author Dr. Jazeel Limzerwala! Both, Jazeel and I started with our PhDs at a similar time, under similar circumstances and with similar attitudes. And despite our opposite personalities, we soon became very good friends. I thank him for all the shared experiences, shared laughs and even for the quarrels we had along the way. I wish him all the very best for his future!
Thank you also to all authors involved in a yet-unpublished story on senescent cells in atherosclerosis that I contributed to, particularly first author Dr. Bennett Childs! I thank him for his time and discussions throughout the years. I will particularly remember the long conversations about science and beyond, often very late at night.
Thank you to all colleagues, former and current, that I haven’t mentioned yet (in alphabetical order): Dr. Mohammed Al-Suraih, Dr. Matej Durik, QianQian Guo, Dr. Arun Kanakkanthara, Jake Kloeber, Ming Li, Dr. HyunJa Nam, Dr. Ryan Naylor, Grace Nelson, John Rainey, Dr. Annyoceli Santiago, Shafiq Shaikh, Shawn Trewartha, Dr. Janine van Ree, Dr. Robbyn Weaver and Wei Zhou.
Thank you to former and current lab members from the closely associated lab of Prof. Dr. Darren Baker (in alphabetical order): Dr. Asef Aziz, Dr. Tyler Bussian, Sara Graves, Taylor McNeely, Charlie Meyer, Pei Ng, Luis Prieto, Rachel Saltness, Dr. Barbara Swenson.
Similarly, thank you to Prof. Dr. Paul Galardy and his lab members (in alphabetical order): Dr. Tibor Bedekovics, Dr. Sajjad Hussain, Dr. Ying Zhang.
A special thank you to Prof. Dr. Richard Bram, chair of the Department of Pediatrics at Mayo Clinic, and Michael Lee, administrator for the Department of Pediatrics, for their highly valuable scientific and non-scientific support. I immensely appreciate their help, time and encouragements particularly throughout the lab transition.
A warm thank you to the administrative assistants that helped me in various aspects throughout the years: Debbie Pearson, Annie Peterson and also briefly Colleen Allen.
I’m also extremely grateful to the Flow Cytometry lab of the Microscopy and Cell Analysis Core at Mayo Clinic. Thank you to Terri Halsey, Drew Kluge, Holly Lamb and Colleen Moe! Without their expertise, time and help, many of my experiments would not have been possible!
Appendices
Similarly, my projects that are based on omics approaches (ChIP-seq, RNA-seq, scRNA-seq) would not have been possible if not for the Medical Genome Facility of the Genome Analysis Core at Mayo Clinic. I’m very grateful to the Medical Genome Facility and all its staff!
Much of my and the lab’s research has been based on mouse analyses and experiments, and I recognize the importance of a well-functioning and well-equipped mouse facility. Therefore, I’m very grateful for the Department of Comparative Medicine and IACUC office at the Mayo Clinic. A warm thank you to all their staff, including all animal care technicians directly handling the lab’s mice. Thank you to the current animal care technicians, Bob Tienter, Maggie Brosig and Michael Sorsen!
I’m extremely grateful to the University of Groningen and all staff who have helped me connect, organize, or supported my PhD program. I’m also extremely thankful to Mayo Clinic and the Mayo Clinic Graduate School of Biomedical Sciences, its dean Prof. Dr. Stephen Ekker and all staff not yet mentioned, who helped and supported me throughout the years. I count myself as extremely fortunate to have been part of such supporting organizations!
I’m also grateful to BioRender and its team for providing a fantastic tool and platform for science illustration. Thanks to BioRender, I was able to design the thesis booklet cover and some of the interior design. I couldn’t have made it without the daily support of my partner, Roman! Despite us working both in separate labs for too many hours daily, and hardly seeing each other for the initial years of my PhD, we somehow managed to still grow closer every day. I thank Roman for all the morning coffees and smoothies, all the car rides and drop-offs, for all the amazing meals he prepared, for letting me sleep as long as I needed on weekends, and so much more. I’m eternally grateful for Roman’s understanding how science works and that things (always) take longer than anticipated. I owe Roman so much, including my sanity. When times were difficult, emotional or chaotic, he would bring me back to balance. Thank you for all your love and always being there for me, Roman!
Thank you to my parents and to my brother, Bernhard, my sister-in-law Kathi, and their two precious sons, Paul and Theo. It has been hard for me not being able to come visit more often and to miss so much back home. I thank them for the weekly calls, texts, updates and the many pictures. Mama and Papa, I’m very grateful for everything that you have taught and instilled in me including the strong work ethic, diligence and persistence.
Thank you to my dear friends in Austria, Kathi Führer and Sabrina Summer! I’m very grateful that they stayed my very close friends despite the long distance and time differences. Thank you for all the encouragements and support throughout the years!
Thank you also to Dr. Laura Meems for her friendship, and for making sure that the Dutch thesis summary actually makes sense!
A special thank you also to my Master’s thesis supervisor, Prof. Dr. Javier Martinez! I’m very thankful for his continued support and guidance, even after completing my Master’s studies and leaving his lab. His excitement and enthusiasm about science have been inspiring and I count myself very lucky to have gotten to know and learn from him!
List of publications
P21 produces a bioactive secretome that places stressed cells under immunosurveillance.
Sturmlechner I, Zhang C, Sine CC, van Deursen EJ, Jeganathan KB, Hamada N, Grasic J, Friedman D,
Stutchman JT, Can I, Hamada M, Lim DY, Lee JH, Ordog T, Laberge RM, Shapiro V, Baker DJ, Li H, van Deursen JM.
Science, under revision.
Vitamin C epigenetically controls osteogenesis and bone mineralization.
Thaler R, Khani F, Denbeigh JM, Sturmlechner I, Zhou X, Pichurin O, Ortega SSJ, Dudakovic A, Zhong
J, Lee JH, Natarajan R, Kalajzic I, Deyle DR, Paschalis EP, Misof B, Ordog T, van Wijnen AJ.
Nature Communications, under revision.
Senescent cells suppress innate smooth muscle cell repair functions in atherosclerosis.
Childs BG, Zhang C, Shuja F, Sturmlechner I, Trewartha S, Velasco RF, Baker DJ, Li H, van Deursen JM.
Nature Aging, accepted ahead of print.
FoxM1 insufficiency hyperactivates Ect2–RhoA–mDia1 signaling to drive cancer.
Limzerwala JF, Jeganathan KB, Kloeber JA, Davies BA, Zhang C, Sturmlechner I, Zhong J, Fierro Velasco
R, Fields AP, Yaxia Yuan, Baker DJ, Zhou D, Li H, Katzmann DJ, van Deursen JM.
Nature Cancer, 2020 Oct 12;1:1010-1024.
BubR1 allelic effects drive phenotypic heterogeneity in mosaic-variegated aneuploidy progeria syndrome.
Sieben CJ, Jeganathan K, Nelson GG, Sturmlechner I, Zhang C, van Deursen W, Bakker B, Foijer F,
Li H, Baker DJ, Van Deursen, JM.
Journal of Clinical Investigation, 2020 Jan 2;130(1):171-188.
Corrigendum: BubR1 allelic effects drive phenotypic heterogeneity in mosaic-variegated aneuploidy progeria syndrome.
Sieben CJ, Jeganathan K, Nelson GG, Sturmlechner I, Zhang C, van Deursen W, Bakker B, Foijer F,
Li H, Baker DJ, Van Deursen, JM.
Journal of Clinical Investigation, 2020 Nov 2;130(11):6188.
Senescent cells in the development of cardiometabolic disease.
Postmus AC, Sturmlechner I, Jonker JW, van Deursen JM, van de Sluis B, Kruit JK.
Current Opinion in Lipidology. 2019 Jun;30(3):177-185.
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Ccne1 Overexpression Causes Chromosome Instability in Liver Cells and Liver Tumor Development in Mice.
Aziz K*, Limzerwala JF*, Sturmlechner I*, Hurley E*, Zhang C, Jeganathan KB, Nelson G, Bronk S,
Velasco RF, van Deursen EJ, O'Brien DR, Kocher JA, Youssef SA, van Ree JH, de Bruin A, van den Bos H, Spierings DCJ, Foijer F, van de Sluis B, Roberts LR, Gores G, Li H, van Deursen JM.
*These authors contribute equally to this study.
Gastroenterology. 2019 Jul;157(1):210-226.e12.
Two-Step Senescence-Focused Cancer Therapies.
Sieben CJ*, Sturmlechner I*, van de Sluis B, van Deursen JM.
*These authors contribute equally to this study.
Trends in Cell Biology. 2018 Sep;28(9):723-737.
Cellular senescence in renal ageing and disease.
Sturmlechner I, Durik M, Sieben CJ, Baker DJ, van Deursen JM.
Nature Reviews Nephrology. 2017 Feb;13(2):77-89.
Anabolic modulation of bone homeostasis by the epigenetic effector sulforaphane, a naturally occurring isothiocyanate.
Thaler R, Maurizi A, Roschger P, Sturmlechner I, Khani, F, Spitzer S, Rumpler M, Zwerina J, Karlic H,
Dudakovic A, Klaushofer K, Teti A, Rucci N, Varga F, van Wijnen AJ.
J Biol Chem. 2016 Mar 25;291(13):6754-71.
Acute-phase protein serum amyloid A3 is a novel paracrine coupling factor that controls bone homeostasis.
Thaler R, Sturmlechner I, Spitzer S, Riester SM, Rumpler M, Zwerina J, Klaushofer K, van Wijnen AJ,
Varga F.
FASEB J. 2015 Apr;29(4):1344-59.
Osteoclasts on Bone and Dentin In Vitro: Mechanism of Trail Formation and Comparison of Resorption Behaviour.
Rumpler M, Würger T, Roschger P, Zwettler E, Sturmlechner I, Altmann P, Fratzl P, Rogers MJ, Klaushofer
K.
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Curriculum vitae
Ines Sturmlechner was born on June 27th 1990 in Krems an der Donau, Austria. She studied Biology at the
University of Vienna (Austria) and graduated as B.Sc. in 2012. She composed a Bachelor’s thesis “Lumican
in Collagen Matrix Structure and Osteoblast Differentiation” based on her research that she conducted at
the Ludwig Boltzmann Institute of Osteology in Vienna. Ines continued her studies with a Master’s program in Molecular Biology at the University of Vienna and graduated with highest honors as M.Sc. in 2014. Her Master’s thesis “Characterization of RTCB knockout mouse embryonic fibroblasts – investigation on the
tRNA ligase complex” was based on her research at the Institute of Molecular Biotechnology (IMBA,
Vienna) under supervision of Prof. Dr. Javier Martinez. During her Bachelor’s and Master’s studies, Ines was fortunate to gain additional research experience at the Department of Chromosome Biology of the Max F. Perutz Laboratories (MFPL) in Vienna under supervision of Prof. Dr. Franz Klein, at the pharmaceutical
company Boehringer Ingelheim RCV (Vienna) under supervision of Drs.Guenther Adolf and Patrizia Sini and at the DKFZ (German Cancer Research Center) in Heidelberg (Germany) under supervision of Prof. Dr. Steeve Boulant.
In early 2015, Ines moved to Rochester, Minnesota (USA) to conduct research on cellular senescence with Prof. Dr. Jan van Deursen at the Department of Pediatrics and Adolescent Medicine at the Mayo Clinic. With the help of Prof. Dr. Marten Hofker, Ines was able to simultaneously pursue her PhD degree at the University of Groningen at the Molecular Genetics section of the Department of Pediatrics, University Medical Center Groningen (UMCG, The Netherlands). During her studies, Ines was selected to partake in the NIH-funded boot camp on “Big data training for translational omics research” at Purdue University, Indiana (USA). For her PhD studies, she was awarded the TOP stipend “Ausland” from the Austrian NOE foundation for Science and Education. In 2019, Ines’ research was also selected for an oral presentation at the 3rd Molecular Biology of Ageing meeting in Groningen.
After the passing of Prof. Dr. Marten Hofker and the retirement of Prof. Dr. Jan van Deursen, Ines’ PhD studies were supervised by Prof. Dr. Bart van de Sluis from the UMCG and Prof. Dr. Bruce Horazdovsky from the Mayo Clinic. Ines continues to work at the Mayo Clinic in Rochester.
