HEXIM1 is a promiscuous double-stranded RNA-binding protein and interacts with RNAs in addition to 7SK in cultured cells.
HEXIM1 is a promiscuous double-stranded RNA-binding protein and interacts with RNAs in addition to 7SK in cultured cells.
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DOI：
10.1093/nar/gkm150
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发表时间：
2007
影响因子：
14.9
通讯作者：
Price DH
中科院分区：
文献类型：
--
作者：
Li Q;Cooper JJ;Altwerger GH;Feldkamp MD;Shea MA;Price DH
P-TEFb在转录延伸水平上调控真核基因表达，其本身受7SK RNA与RNA结合蛋白HEXIM1或HEXIM2的可逆结合控制。为了确定7SK在体外与HEXIM1相互作用所需的最小区域，我们发现由核苷酸10-48组成的寡核苷酸就足够了。进一步缩小7SK最小区域的努力导致了一个令人惊讶的发现，即HEXIM1以序列无关的方式与双链RNA结合。dsRNA和7SK（10-48）与全长7SK在体外有效结合HEXIM1。结合dsRNA后，在HEXIM1中观察到一个大的构象变化，允许P-TEFb的招募和抑制。亚细胞分离和免疫荧光都表明，虽然大多数HEXIM1存在于细胞核中，但在细胞质中发现了相当一部分。免疫沉淀实验表明，细胞核和细胞质中的HEXIM1都与RNA相关。有趣的是，检测到的一种microRNA （mir-16）在HEXIM1免疫沉淀中发现，而小核rna U6和U2则没有发现。我们的研究阐明了HEXIM1在体外和体内的新特性，并表明除了控制P-TEFb外，HEXIM1可能还参与其他核和细胞质过程。
P-TEFb regulates eukaryotic gene expression at the level of transcription elongation, and is itself controlled by the reversible association of 7SK RNA and an RNA-binding protein HEXIM1 or HEXIM2. In an effort to determine the minimal region of 7SK needed to interact with HEXIM1 in vitro, we found that an oligo comprised of nucleotides 10–48 sufficed. A bid to further narrow down the minimal region of 7SK led to a surprising finding that HEXIM1 binds to double-stranded RNA in a sequence-independent manner. Both dsRNA and 7SK (10–48), but not dsDNA, competed efficiently with full-length 7SK for HEXIM1 binding in vitro. Upon binding dsRNA, a large conformational change was observed in HEXIM1 that allowed the recruitment and inhibition of P-TEFb. Both subcellular fractionation and immunofluorescence demonstrated that, while most HEXIM1 is found in the nucleus, a significant fraction is found in the cytoplasm. Immunoprecipitation experiments demonstrated that both nuclear and cytoplasmic HEXIM1 is associated with RNA. Interestingly, the one microRNA examined (mir-16) was found in HEXIM1 immunoprecipitates, while the small nuclear RNAs, U6 and U2, were not. Our study illuminates novel properties of HEXIM1 both in vitro and in vivo, and suggests that HEXIM1 may be involved in other nuclear and cytoplasmic processes besides controlling P-TEFb.
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影响因子：
4.8
作者：
Fu, TJ;Peng, JM;Flores, O
通讯作者：
Flores, O
影响因子：
16
作者：
Barboric, M;Nissen, RM;Peterlin, BM
通讯作者：
Peterlin, BM
影响因子：
4.8
作者：
Dulac, C;Michels, AA;Bensaude, O
通讯作者：
Bensaude, O
影响因子：
64.8
作者：
Nguyen, VT;Kiss, TS;Bensaude, O
通讯作者：
Bensaude, O
DOI：
10.1101/sqb.1998.63.371
发表时间：
1998-01-01
期刊：
COLD SPRING HARBOR SYMPOSIA ON QUANTITATIVE BIOLOGY
影响因子：
--
作者：
Garber, ME;Wei, P;Jones, KA
通讯作者：
Jones, KA