The role of p53 dependent and cooperating pathways in pluripotency induction
Final Report Abstract
Our studies within the SPP1356 revealed the first experimental evidence that the differentiation stage of liver cells from adult and fetal mice determines the potential to reprogram into pluripotent cells after introduction of pluripotency factors (KLF4, c-myc, Nanog, Oct4). The study showed that the enhanced expression of components of the chromatin remodeling BAF complex associated with increased reprogramming capacity of liver stem and progenitor cells as compared to differentiated liver cells. In parallel studies in mouse models we showed thatp53 dependent DNA damage signal impair the self renewal and function of adult tissue stem cells in response to telomere shortening. Lentiviral screening on mouse fibroblast from p53+/+ and p53-/- mice identified Igfbp7 as a gene inhibiting the reprogramming of p53-/- fibroblasts into iPS cells. p53-independent regulation of Igfbp7 has not previously been associated with pluripotency induction or stem cell functionality. Candidate shRNA experiments verified that Igfbp7 knockdown increases the reprogramming of p53-/- fibroblasts into iPS cells. Inducible igfbp7-shRNA knockin mice were generated and revealed first experimental evidence that the knockdown of Igfbp7 leads to an expansion of phenotypic HSCs in bone marrow of adult mice and to the development of aneuploidy in hematopoietic bone marrow cells. these data provide a proof of concept that shRNA screening on iPS cells can lead to the identification of genetic factors that also influence the self-renewal and stability of adult tissue stem cells. Further work is required to delineate p53-dependent and -independent regulation of Igfbp7 expression in stem cells in response to DNA damage and pluripotency induction.
Publications
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DNA damage checkpoints in stem cells, ageing and cancer. Nat Rev Mol Cell Biol. 2012; 13:579-90
Sperka T, Wang J, Rudolph KL
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Increased Reprogramming Capacity of Mouse Liver Progenitor Cells, Compared With Differentiated Liver Cells, Requires the BAF Complex. Gastroenterology. 2012, 142:907-17
Kleger A, Mahaddalkar P, Katz SF, Lechel A, Ju JY, Loya K, Lin Q, Hartmann D, Liebau S, Kraus J, Cantz T, Kestler HA, Zaehres H, Schöler H, Rudolph KL
