title: Acetylation of the proto-oncogene EVI1 abrogates Bcl-xL promoter binding and induces apoptosis.
abstract: EVI1 (Ecotropic Viral Integration site I), which was originally identified as a myeloid transforming gene by means of retroviral insertional mutagenesis in mouse leukemia, encodes a nuclear DNA binding zinc finger protein. The presence of zinc fingers that are able to bind to specific sequences of DNA suggests that EVI1 is a transcriptional regulator; however, except a few, target genes of EVI1 are poorly functionally identified thus far. In this study we provide evidence that EVI1 directly induces the expression of Bcl-xL through the first set of zinc finger and thereby inhibits apoptosis. ChIP analysis showed that EVI1 binds to the Bcl-xL promoter in HT-29 cells, a colon carcinoma cell line, which expresses EVI1. The observation is also supported by the fact that EVI1 siRNA treated HT-29 cells, shows a down regulation of Bcl-xL expression and that over expression of EVI1 results in the induction of the Bcl-xL reporter construct. A set of EVI1 positive chronic myeloid leukemia (CML) samples also showed higher Bcl-xL expression with respect to EVI1 negative samples. Interestingly, co-expression of EVI1 with wild type, but not with dominant-negative form of PCAF, abolishes the effect of EVI1 on Bcl-xL, indicating that acetylation of EVI1 abrogates its ability not only to bind Bcl-xL promoter but also alleviate Bcl-xL activity. Finally we have shown that EVI1 expression regulates apoptosis in HT-29 cells, which is abrogated when HT-29 cells are transfected with EVI1 siRNA or PCAF. The result for the first time shows a direct pathway by which EVI1 can protect cells from apoptosis and also demonstrates that the pathway can be reversed when EVI1 is acetylated.
authors: Department of Gene Function and Regulation, Institute of Life Sciences, Bhubaneswar, Orissa, India.
authors: Anjan Kumar
authors: AK
authors: Pradhan
authors: Alok Das
authors: AD
authors: Mohapatra
authors: Kasturi Bala
authors: KB
authors: Nayak
authors: Soumen
authors: S
authors: Chakraborty
mesh_terms: D000107:Acetylation; D000818:Animals; D017209:Apoptosis; D001483:Base Sequence; D002417:Cattle; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism*; D004285:Dogs; D015536:Down-Regulation / Q000235:genetics; D057809:HEK293 Cells; D019073:HT29 Cells; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D041681:NIH 3T3 Cells; D011401:Promoter Regions, Genetic / Q000235:genetics*; D011485:Protein Binding; D000090063:Proto-Oncogene Mas; D011519:Proto-Oncogenes; D051381:Rats; D014158:Transcription, Genetic / Q000235:genetics; D015854:Up-Regulation / Q000235:genetics; D016335:Zinc Fingers; D051020:bcl-X Protein / Q000235:genetics*; D050880:p300-CBP Transcription Factors / Q000378:metabolism; D000099224:p300-CBP-Associated Factor
chemical_list: D004268:DNA-Binding Proteins; D000090063:Proto-Oncogene Mas; D051020:bcl-X Protein; D050880:p300-CBP Transcription Factors; D000099224:p300-CBP-Associated Factor; C000715470:MAS1 protein, human