tailieunhanh - Báo cáo khoa học: The Drosophila homeodomain transcription factor, Vnd, associates with a variety of co-factors, is extensively phosphorylated and forms multiple complexes in embryos

Vnd is a dual transcriptional regulator that is essential forDrosophila dor-sal–ventral patterning. Yet, our understanding of the biochemical basis for its regulatory activity is limited. Consistent with Vnd’s ability to repress target expression in embryos, endogenously expressed Vnd physically asso-ciates with the co-repressor, Groucho, inDrosophilaKc167 cells. | ễFEBS Journal The Drosophila homeodomain transcription factor Vnd associates with a variety of co-factors is extensively phosphorylated and forms multiple complexes in embryos Huanqing Zhang1 z Li-Jyun Syu1 f Vicky Modica1 Zhongxin Yu1 Tonia Von Ohlen2 and Dervla M. Mellerick1 1 MSRBIII Ann Arbor MI USA 2 Division of Biology Kansas State University Manhattan KS USA Keywords co-factor complex regulation transcription Vnd Correspondence D. M. Mellerick Med Sci I M5240 Ann Arbor MI 48109-0602 USA Fax 1 734 369 3874 Tel 1 734 709 3222 E-mail dervlamellerick@ Present address 5051 BSRB Ann Arbor MI USA 1500 E. MedicalCenter Drive Ann Arbor MI USA Received 28 April2008 revised 23 July 2008 accepted 12 August 2008 doi Vnd is a dual transcriptional regulator that is essential for Drosophila dorsal-ventral patterning. Yet our understanding of the biochemical basis for its regulatory activity is limited. Consistent with Vnd s ability to repress target expression in embryos endogenously expressed Vnd physically associates with the co-repressor Groucho in Drosophila Kc167 cells. Vnd exists as a single complex in Kc167 cells in contrast with embryonic Vnd which forms multiple high-molecular-weight complexes. Unlike its vertebrate homolog full-length Vnd can bind its target in electrophoretic mobility shift assay suggesting that co-factor availability may influence Vnd s weak regulatory activity in transient transfections. We identify the high mobility group 1-type protein D1 and the novel helix-loop-helix protein Olig as novel Vnd-interacting proteins using co-immunoprecipitation assays. Furthermore we demonstrate that both D1 and Olig are co-expressed with Vnd during Drosophila embryogenesis consistent with a biological basis for this interaction. We also suggest that the phosphorylation state of Vnd influences its ability to interact with co-factors because Vnd is extensively phosphorylated in embryos and can be phosphorylated .