The first bromodomain of Brdt, a testis-specific member of the BET sub-family of double-bromodomain-containing proteins, is essential for male germ cell differentiation
The first bromodomain of Brdt, a testis-specific member of the BET sub-family of double-bromodomain-containing proteins, is essential for male germ cell differentiation
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DOI：
10.1242/dev.004481
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发表时间：
2007-10-01
期刊：
影响因子：
4.6
通讯作者：
Wolgemuth, Debra J.
中科院分区：
文献类型：
--
作者：
Shang, Enyuan;Nickerson, Helen D.;Wolgemuth, Debra J.
Brdt是含溴结构域基序的蛋白质的独特BET亚家族的睾丸特异性成员，溴结构域基序是结合乙酰化赖氨酸并涉及染色质重塑的基序。其表达仅限于生殖细胞系，特别是粗线期和双线期精母细胞和早期精子细胞。靶向诱变用于产生携带Brdt突变等位基因Brdt（Δ BD 1）的小鼠，其仅缺乏独特表征BET蛋白的两个溴结构域中的第一个。纯合子Brdt（Delta BD 1/Delta BD 1）小鼠存活，但雄性不育，产生较少的精子和形态异常的精子。异常形态发生首先在第9步的精子细胞伸长中被检测到，并且那些形成的精子细胞在核膜处缺乏异染色质的独特灶。定量逆转录-聚合酶链反应（RT- PCR）显示组蛋白H1 t（Hist 1h 1 t）在Brdt（Delta BD 1/Delta BD 1）睾丸中的水平增加了3倍，染色质免疫沉淀显示Brdt蛋白而不是Brdt（Delta BD 1）蛋白与H1 t的启动子相关。胞浆内单精子注射表明Brdt（Delta BD 1）突变体精子中的DNA可以支持早期胚胎发育并产生功能性胚胎干细胞。这是首次证明在含溴结构域蛋白的BET亚家族成员中缺失两个溴结构域中的仅一个对体内分化具有深远影响。
Brdt is a testis- specific member of the distinctive BET sub- family of bromodomain motif- containing proteins, a motif that binds acetylated lysines and is implicated in chromatin remodeling. Its expression is restricted to the germ line, specifically to pachytene and diplotene spermatocytes and early spermatids. Targeted mutagenesis was used to generate mice carrying a mutant allele of Brdt, Brdt(Delta BD1), which lacks only the first of the two bromodomains that uniquely characterize BET proteins. Homozygous Brdt(Delta BD1/Delta BD1) mice were viable but males were sterile, producing fewer and morphologically abnormal sperm. Aberrant morphogenesis was first detected in step 9 elongating spermatids, and those elongated spermatids that were formed lacked the distinctive foci of heterochromatin at the peri- nuclear envelope. Quantitative reverse transcription ( RT)- PCR showed threefold increased levels of histone H1t ( Hist1h1t) in Brdt(Delta BD1/Delta BD1) testes and chromatin immunoprecipitation revealed that Brdt protein, but not Brdt(Delta BD1) protein, was associated with the promoter of H1t. Intracytoplasmic sperm injection suggested that the DNA in the Brdt(Delta BD1) mutant sperm could support early embryonic development and yield functional embryonic stem cells. This is the first demonstration that deletion of just one of the two bromodomains in members of the BET sub- family of bromodomain- containing proteins has profound effects on in vivo differentiation.