Project description:Thyroid Transcription Factor-1 (TTF-1) is a key regulator of thyroid development and function. In order to identify the genes whose expression depends on TTF-1 transcriptional activity within the thyrocyte we analyzed the consequence of the functional inactivation of this factor in PCCl3 cells. The expression of a fusion protein composed of the DNA binding domain of TTF-1 and of the strong repressive domain of the Engrailed protein (Engr HD) resulted in a dramatic loss of epithelial cell morphology and in proliferation arrest. These changes were reversed when the inhibition of endogenous TTF-1 was relieved. No change was observed when a similar fusion protein containing point mutations abolishing DNA binding activity (Engr HDm) was produced in the cells.
Project description:A chromosomal translocation results in production of an oncogenic PAX8-PPARG fusion protein (PPFP) in a subset of thyroid carcinomas. PAX8 is an important thyroid transcription factor, and PPARG is a transcription factor that plays important roles in the biology of adipocytes and macrophages, but has no known function in the thyroid. PPFP retains the DNA binding domains of both proteins. However, the genomic DNA binding sites of PPFP have not been identified, and only limited data exist to characterize gene expression in PPFP thyroid carcinomas. Therefore, we expressed PPFP in PCCL3 rat thyroid cells and used ChIP-seq to identify PPFP genomic binding sites (PPFP peaks) and RNA-seq to characterize PPFP-dependent gene expression. The genome contains ~20 000 PPFP peaks, including known PAX8 and PPARG binding sites, indicating that both DNA binding domains are functional. PPFP binds to and regulates many genes involved in cancer-related processes such as development and cell division. PPFP also binds to and regulates many genes related to mitochondria and lipid metabolism that are regulated by PPARG in adipocytes. Our data highlight the complexity of PPFP as a transcription factor and the numerous ways that it regulates thyroid oncogenesis.
Project description:Comparison of cistromes from PAX8, NKX2.1, and FOXE1 ChIP-Seq analysis using mouse thyroid gland and rat thyrocyte PCCl3 cells revealed that there is a significant overlap between GLIS3 binding regions and those of PAX8, NKX2.1, and FOXE1 in genes associated with thyroid hormone biosynthesis.
Project description:Analysis of PAX8 binding sites by chromatin immunoprecipitation coupled with ultra-high-throughput sequencing (ChIP-seq) in PCCL3 rat cells. Results provide insight into the contribution of this regulatory factor to transcription genome-wide. We generate a genome wide map of PAX8 binding sites in PCCL3 cells using as negative control an input DNA obtained just prior to Pax8 immunoprecipitation
