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BET Protein BRDT Complexes With HDAC1, PRMT5, and TRIM28 and Functions in Transcriptional Repression During Spermatogenesis
Author(s) -
Wang Li,
Wolgemuth Debra J.
Publication year - 2016
Publication title -
journal of cellular biochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.028
H-Index - 165
eISSN - 1097-4644
pISSN - 0730-2312
DOI - 10.1002/jcb.25433
Subject(s) - bromodomain , protein arginine methyltransferase 5 , microbiology and biotechnology , biology , chromatin remodeling , spermiogenesis , chromatin , spermatid , histone , genetics , gene , methyltransferase , nucleus , methylation , sperm
The expression of BRDT, a member of the BET sub‐family of double bromodomain‐containing proteins, is restricted to the male germ line, specifically to pachytene‐diplotene spermatocytes and early spermatids. We previously showed that loss of the first bromodomain of BRDT by targeted mutagenesis ( Brdt ΔBD1 ) resulted in sterility and abnormalities in spermiogenesis, but little is known about BRDT's function at the molecular level. As part of studies designed to identify BRDT‐interacting proteins we stably introduced a FLAG‐tagged BRDT cDNA into 293T cells, which do not normally express BRDT. Affinity‐purification of FLAG‐tagged BRDT complexes indicated that BRDT has novel interactions with the histone deacetylase HDAC1, the arginine‐specific histone methyltransferase 5 PRMT5, and the Tripartite motif‐containing 28 protein TRIM28. Immunofluorescent microscopy revealed that BRDT co‐localized with each of these proteins in round spermatids and co‐immunoprecipitation of testicular extracts showed that these proteins interact with BRDT. Furthermore, they bind the promoter of H1t , a putative target of BRDT‐containing complexes. This binding of H1t was lost in mice expressing the Brdt ΔBD1 mutant protein and concomitantly, H1t expression was elevated in round spermatids. Our study reveals a role for BRDT‐containing complexes in the repression of gene expression in vivo that correlates with dramatic effects on chromatin remodeling and the progression of spermiogenesis. J. Cell. Biochem. 117: 1429–1438, 2016. © 2015 Wiley Periodicals, Inc.