Targeting TGFβ signaling pathway in fibrosis and cancer

Cancer and fibrosis are devastating diseases of high mortality rate and with limited curative therapies available. A better understanding of the biological drivers of these diseases is fundamental in order to develop effective therapeutics. At the molecular level, signaling pathways control cell growth, differentiation or apoptosis during development and adult life of the organism ensuring homeostasis. Paradoxically, the same signals are often implicated or even drive disease progression. One of the signaling pathways with key regulatory functions in homeostasis, tissue fibrosis and cancer in many organs is the TGFβ/BMP pathway. In this thesis we addressed the role and therapeutic potential of TGFβ/BMP pathway inhibition using different drug compounds that are currently towards the clinic or being tested in clinical trials. Three distinct types of inhibitors were used; small molecule inhibitors of the ALK4, 5 and 7 TGFβ receptor kinases, an antisense oligonucleotide interfering with ALK5 mRNA splicing and an ALK1 ligand trap; a peptide that contains the extracellular domain of ALK1 fused to Fc and sequesters BMP9 and BMP10. These inhibitors were used in an ex vivo human fibrosis model and in vivo mouse models of various human diseases (acute liver failure/ liver regeneration, Dupuytren's fibrosis) and cancer (prostate, liver).UBL - phd migration 201

Epigenetic events underlying somatic cell reprogramming

Although differentiated cells normally retain cell-type-specific gene expression patterns throughout their lifetime, cell identity can sometimes be modified or reversed in vivo by transdifferentiation, or experimentally through cell fusion or by nuclear transfer. Several studies have illustrated the importance of chromatin remodelling, DNA demethylation and dominant transcriptional factor expression for changes in lineage identity. Here the epigenetic mechanisms required to “reset” genome function were investigated using experimental heterokaryons. To examine the epigenetic changes that are required for the dominant conversion of lymphocytes to muscle, I generated stable heterokaryons between human B-lymphocytes and mouse C2C12 myotubes. I show that lymphocyte nuclei adopt an architecture resembling that of muscle and initiate the expression of musclespecific genes in the same temporal order as developing muscle. The establishment of this novel gene expression program is coordinated with the shutdown of several lymphocyte-associated genes. Interestingly, inhibition of histone deacetylase (HDAC) activity during reprogramming selectively blocks the silencing of lymphocyte-specific genes but does not prevent the establishment of muscle-specific gene expression. In order to reprogram somatic cells to pluripotency, I fused human Blymphocytes and mouse embryonic stem (ES) cells. The conversion of human cells is initiated rapidly, occurring in heterokaryons before nuclear fusion. Reprogramming of human lymphocytes by mouse ES cells elicits the expression of a human ES-specific gene expression profile in which endogenous hSSEA4, hFgf receptors and ligands are expressed while factors that are characteristic of mouse ES cells, such as Bmp4 and Lif receptor are not. Using genetically engineered mouse ES cells I demonstrate that successful reprogramming requires the expression of Oct4, but importantly, does not require Sox2, a factor implicated as critical for the induction of pluripotency. Following reprogramming, mOct4 becomes dispensable for maintaining the multi-potent state of hybrid cells. Finally, I have examined the reprogramming potential of embryonic germ (EG), embryonic carcinoma (EC) and ES cells deficient for the Polycomb repressive complex 2 (PRC2) proteins Eed, Suz12 and Ezh2. While EC and EG cells share the ability to reprogram human lymphocytes with ES cells, the lack of Polycomb proteins abolishes reprogramming. Thus, the repressive chromatin mark (H3K27 methylation) catalysed by PRC2 play a crucial role in keeping ES cells with full reprogramming capacity. Collectively my results underscore the importance of chromatin events during cell fate reprogramming

Xenopus

This book focuses on the amphibian, Xenopus, one of the most commonly used model animals in the biological sciences. Over the past 50 years, the use of Xenopus has made possible many fundamental contributions to our knowledge in cell biology, developmental biology, molecular biology, and neurobiology. In recent years, with the completion of the genome sequence of the main two species and the application of genome editing techniques, Xenopus has emerged as a powerful system to study fundamental disease mechanisms and test treatment possibilities. Xenopus has proven an essential vertebrate model system for understanding fundamental cell and developmental biological mechanisms, for applying fundamental knowledge to pathological processes, for deciphering the function of human disease genes, and for understanding genome evolution. Key Features Provides historical context of the contributions of the model system Includes contributions from an international team of leading scholars Presents topics spanning cell biology, developmental biology, genomics, and disease model Describes recent experimental advances Incorporates richly illustrated diagrams and color images Related Titles Green, S. L. The Laboratory Xenopus sp. (ISBN 978-1-4200-9109-0) Faber, J. & P. D. Nieuwkoop. Normal Table of Xenopus laevis (Daudin): A Systematical & Chronological Survey of the Development from the Fertilized Egg till the End of Metamorphosis (ISBN 978-0-8153-1896-5) Jarret, R. L. & K. McCluskey. The Biological Resources of Model Organisms (ISBN 978-1-0320-9095-5