Armstrong Jennifer A, Papoulas Ophelia, Daubresse Gary, Sperling Adam S, Lis John T, Scott Matthew P, Tamkun John W
Department of Molecular, Cell, and Developmental Biology, University of California-Santa Cruz, Santa Cruz, CA 95064, USA.
EMBO J. 2002 Oct 1;21(19):5245-54. doi: 10.1093/emboj/cdf517.
Drosophila brahma (brm) encodes the ATPase subunit of a 2 MDa complex that is related to yeast SWI/SNF and other chromatin-remodeling complexes. BRM was identified as a transcriptional activator of Hox genes required for the specification of body segment identities. To clarify the role of the BRM complex in the transcription of other genes, we examined its distribution on larval salivary gland polytene chromosomes. The BRM complex is associated with nearly all transcriptionally active chromatin in a pattern that is generally non-overlapping with that of Polycomb, a repressor of Hox gene transcription. Reduction of BRM function dramatically reduces the association of RNA polymerase II with salivary gland chromosomes. A few genes, such as induced heat shock loci, are not associated with the BRM complex; transcription of these genes is not compromised by loss of BRM function. The distribution of the BRM complex thus correlates with a dependence on BRM for gene activity. These data suggest that the chromatin remodeling activity of the BRM complex plays a general role in facilitating transcription by RNA polymerase II.
果蝇的brahma（brm）基因编码一个2 MDa复合物的ATP酶亚基，该复合物与酵母SWI/SNF及其他染色质重塑复合物相关。BRM被鉴定为决定体节特征所需的Hox基因的转录激活因子。为阐明BRM复合物在其他基因转录中的作用，我们检测了它在幼虫唾液腺多线染色体上的分布。BRM复合物与几乎所有转录活跃的染色质相关，其模式通常与Hox基因转录抑制因子多梳蛋白（Polycomb）的模式不重叠。BRM功能的降低显著减少了RNA聚合酶II与唾液腺染色体的结合。少数基因，如诱导热休克基因座，不与BRM复合物相关；这些基因的转录不受BRM功能丧失的影响。因此，BRM复合物的分布与基因活性对BRM的依赖性相关。这些数据表明，BRM复合物的染色质重塑活性在促进RNA聚合酶II的转录中起普遍作用。
