Polyhomeotic stably associates with molecular chaperones Hsc4 and Droj2 in Drosophila Kc1 cells

被引:16
作者
Wang, YJ [1 ]
Brock, HW [1 ]
机构
[1] Univ British Columbia, Dept Zool, Vancouver, BC V6T 1Z4, Canada
基金
加拿大健康研究院;
关键词
polyhomeotic; chaperone; general transcription factor; silencing; polycomb group; chromatin;
D O I
10.1016/S0012-1606(03)00396-8
中图分类号
Q [生物科学];
学科分类号
07 ; 0710 ; 09 ;
摘要
Polycomb group (PcG) proteins silence target loci in Drosophila. Although the mechanism of PcG-mediated silencing remains unknown, there is considerable evidence that PcG proteins act via multiple complexes. We have epitope-tagged Polyhomeotic Proximal, PHP, the major isoform of the proximal product of the polyhomeotic locus, at both termini (F-PHP-HA) and generated a stable Kc1 cell line in order to isolate F-PHP-HA-associated proteins. Using either column chromatography followed by immunoaffinity precipitation or a double immunoaffinity precipitation procedure, we observed multiple proteins that stably associate with F-PHP-HA. Sequencing the five major bands identified PHP-170 and PHP-140 isoforms, Polycomb, Heat shock cognate 4 (Hsc4), and a novel Drosophila J class chaperone we term Droj2. Mutations in both chaperone genes enhance homeotic transformations in PcG genes, suggesting that they have a role in silencing. We show by Western blotting that minor components of F-PHP-HA-associated proteins include TBP, TAF(II)42, TAF(II)85, and p55. However, unlike in PRC1, Psc, TAF(II)62, Modulo, dMI-2, or Rpd3/HDAC1 do not associate with F-PHP-HA. We discuss the role of chaperones and F-PHP-HA-associated proteins in PcG-mediated silencing and the evidence for different complexes containing Polyhomeotic in vivo. (C) 2003 Elsevier Inc. All rights reserved.
引用
收藏
页码:350 / 360
页数:11
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