Mammalian SWI-SNF complexes contribute to activation of the hsp70 gene
Mammalian SWI-SNF complexes contribute to activation of the hsp70 gene
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DOI：
10.1128/mcb.20.8.2839-2851.2000
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发表时间：
2000-04-01
影响因子：
5.3
通讯作者：
Imbalzano, AN
中科院分区：
文献类型：
--
作者：
De la Serna, IL;Carlson, KA;Imbalzano, AN
ATP依赖的染色质重塑复合物在所有真核生物中是保守的，其功能是通过改变核小体结构来允许细胞调节因子进入DNA。哺乳动物SWI-SNF复合物含有两个高度保守的ATP酶亚基：BRG 1或BRM。为了鉴定需要哺乳动物SWI-SNF复合物来激活基因表达的细胞基因，我们已经产生了诱导表达不能结合和水解ATP的BRG 1或BRM ATP酶的突变形式的细胞系。突变体亚基与哺乳动物SWI-SNF复合物的至少两个内源性成员物理相关，表明可能形成非功能性显性负性复合物。我们确定突变BRG 1或BRM蛋白的表达损害了细胞激活内源性应激反应基因hsp 70的能力，以响应亚砷酸盐（一种代谢抑制剂）或镉（一种重金属）。然而，热应激对热休克蛋白70的激活不受影响。血红素加氧酶1启动子的激活亚砷酸盐或镉和镉诱导的金属硫蛋白启动子的激活也不受突变体SWI-SNF组件的表达。组成型表达基因的一个子集的分析显示，没有或最小的影响转录水平。我们建议，哺乳动物SWI-SNF复合物在基因激活事件的要求将具体到个别基因和信号通路。
ATP-dependent chromatin-remodeling complexes are conserved among all eukaryotes and function by altering nucleosome structure to allow cellular regulatory factors access to the DNA. Mammalian SWI-SNF complexes contain either of two highly conserved ATPase subunits: BRG1 or BRM. To identify cellular genes that require mammalian SWI-SNF complexes for the activation of gene expression, we have generated cell lines that inducibly express mutant forms of the BRG1 or BRM ATPases that are unable to bind and hydrolyze ATP. The mutant subunits physically associate with at least two endogenous members of mammalian SWI-SNF complexes, suggesting that nonfunctional, dominant negative complexes may be formed. We determined that expression of the mutant BRG1 or BRM proteins impaired the ability of cells to activate the endogenous stress response gene hsp70 in response to arsenite, a metabolic inhibitor, or cadmium, a heavy metal. Activation of hsp70 by heat stress, however, was unaffected. Activation of the heme oxygenase 1 promoter by arsenite or cadmium and activation of the cadmium-inducible metallothionein promoter also were unaffected by the expression of mutant SWI-SNF components. Analysis of a subset of constitutively expressed genes revealed no or minimal effects on transcript levels. We propose that the requirement for mammalian SWI-SNF complexes in gene activation events will be specific to individual genes and signaling pathways.