title: Human RNA polymerase II-association factor 1 (hPaf1/PD2) regulates histone methylation and chromatin remodeling in pancreatic cancer.
abstract: Change in gene expression associated with pancreatic cancer could be attributed to the variation in histone posttranslational modifications leading to subsequent remodeling of the chromatin template during transcription. However, the interconnected network of molecules involved in regulating such processes remains elusive. hPaf1/PD2, a subunit of the human PAF-complex, involved in the regulation of transcriptional elongation has oncogenic potential. Our study explores the possibility that regulation of histone methylation by hPaf1 can contribute towards alteration in gene expression by nucleosomal rearrangement. Here, we show that knockdown of hPaf1/PD2 leads to decreased di- and tri-methylation at histone H3 lysine 4 residues in pancreatic cancer cells. Interestingly, hPaf1/PD2 colocalizes with MLL1 (Mixed Lineage Leukemia 1), a histone methyltransferase that methylates H3K4 residues. Also, a reduction in hPaf1 level resulted in reduced MLL1 expression and a corresponding decrease in the level of CHD1 (Chromohelicase DNA-binding protein 1), an ATPase dependent chromatin remodeling enzyme that specifically binds to H3K4 di and trimethyl marks. hPaf1/PD2 was also found to interact and colocalize with CHD1 in both cytoplasmic and nuclear extracts of pancreatic cancer cells. Further, reduced level of CHD1 localization in the nucleus in hPaf1/PD2 Knockdown cells could be rescued by ectopic expression of hPaf1/PD2. Micrococcal nuclease digestion showed an altered chromatin structure in hPaf1/PD2-KD cells. Overall, our results suggest that hPaf1/PD2 in association with MLL1 regulates methylation of H3K4 residues, as well as interacts and regulates nuclear shuttling of chromatin remodeling protein CHD1, facilitating its function in pancreatic cancer cells.
authors: Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, Nebraska, United States of America.
authors: Parama
authors: P
authors: Dey
authors: Moorthy P
authors: MP
authors: Ponnusamy
authors: Shonali
authors: S
authors: Deb
authors: Surinder K
authors: SK
authors: Batra
mesh_terms: D042002:Chromatin Assembly and Disassembly; D004265:DNA Helicases / Q000378:metabolism* / Q000502:physiology; D004268:DNA-Binding Proteins / Q000378:metabolism* / Q000502:physiology; D015972:Gene Expression Regulation, Neoplastic; D011495:Histone-Lysine N-Methyltransferase; D006657:Histones / Q000378:metabolism*; D006801:Humans; D008745:Methylation; D051788:Myeloid-Lymphoid Leukemia Protein / Q000378:metabolism* / Q000502:physiology; D009687:Nuclear Proteins / Q000502:physiology*; D010190:Pancreatic Neoplasms / Q000235:genetics* / Q000473:pathology; D012319:RNA Polymerase II; D014157:Transcription Factors; D014407:Tumor Cells, Cultured
chemical_list: D004268:DNA-Binding Proteins; D006657:Histones; C497422:KMT2A protein, human; D009687:Nuclear Proteins; C501972:PAF1 protein, human; D014157:Transcription Factors; D051788:Myeloid-Lymphoid Leukemia Protein; D011495:Histone-Lysine N-Methyltransferase; D012319:RNA Polymerase II; D004265:DNA Helicases; C080359:CHD1 protein, human