Studies of Chromatin Remodeling Factors

描述（由申请人提供）：核小体和其他组分 染色质可以作为转录的有效调节因子，通过调节 调节蛋白进入DNA。通过改变结构和间距 在核小体中，ATF的SWI 2/SNF 2家族的成员可以激活或抑制 转录。关于这些染色质重塑是如何发生的， 因子针对特定基因;它们的活性如何调节;以及 它们如何相互作用以及组蛋白修饰酶如何调节 染色质结构和转录。为了解决这些重要问题，我们 正在研究果蝇中三种不同的染色质重塑因子： (BRM)、Kismet（KIS）和模仿开关（ISWI）。遗传学研究表明 BRM和KIS在转录激活中起着相似的作用，而ISWI 可以作为转录抑制因子。BRM和ISWI起ATP酶的作用 不同染色质重塑复合物的亚基。生化活性 的KIS还没有被表征，但它的序列表明，它也有 染色质重塑活性。我们的长期目标是阐明 KIS、ISWI和BRM的行动。增强子和抑制子的基因筛选 显性负染色质表达导致的表型 重塑因子将进行鉴定的基因和蛋白质与 它们在体内相互作用DNA微阵列将被用来检查 由染色质重塑因子突变引起的基因表达。遗传 将使用分析来研究染色质的乙酰化是否 影响其与染色质重塑因子相互作用的能力。中 补充系列生化实验，KIS和相关蛋白质 将从胚胎提取物中提纯，并测试重塑 体外染色质。果蝇染色质重塑因子的人类同源物 参与转录调控、病毒整合、细胞周期 控制和癌症。BRG 1，人类brm同源物，与 视网膜母细胞瘤肿瘤抑制蛋白;这种相互作用的破坏导致 恶性转化BRCA 1是BRG 1复合物的一种成分， 这表明BRG 1功能的改变使个体易患乳腺癌， 和卵巢癌此外，BRM的INI 1亚基中的突变 在恶性横纹肌样瘤中已经鉴定出这种复合物。因此 从果蝇染色质重塑因子研究中获得的信息 应该与人类疾病直接相关。

DESCRIPTION (provided by applicant): Nucleosomes and other components of chromatin can act as potent regulators of transcription by modulating the access of regulatory proteins to DNA. By altering the structure and spacing of nucleosomes, members of the SWI2/SNF2 family of ATFases can activate or repress transcription. Much remains to be learned about how these chromatin-remodeling factors are targeted to specific genes; how their activities are regulated; and how they interact with each other and histone modifying enzymes to modulate chromatin structure and transcription. To address these important issues, we are studying three different chromatin-remodeling factors in Drosophila: Brahma (BRM), Kismet (KIS) and Imitation-switch (ISWI). Genetic studies have suggested that BRM and KIS play similar roles in transcriptional activation, while ISWI may act as a transcriptional repressor. BRM and ISWI function as the ATPase subunits of distinct chromatin remodeling complexes. The biochemical activities of KIS have not been characterized, but its sequence suggests that it also has chromatin remodeling activity. Our long-term goal is to elucidate the mechanism of action of KIS, ISWI and BRM. Genetic screens for enhancers and suppressors of phenotypes resulting from the expression of dominant-negative chromatin remodeling factors will be conducted to identify the genes and proteins with which they interact in vivo. DNA microarrays will be used to examine changes in gene expression caused by mutations in chromatin remodeling factors. Genetic assays will be used to investigate whether the acetylation of chromatin influences its ability to interact with chromatin remodeling factors. In a complementary series of biochemical experiments, KIS and associated proteins will be purified from embryo extracts and tested for the ability to remodel chromatin in vitro. Human homologs of Drosophila chromatin remodeling factors are involved in transcriptional regulation, viral integration, cell cycle control and cancer. BRG1, the human brm homolog, physically interacts with the retinoblastoma tumor suppressor protein; disruption of this interaction leads to malignant transformation. BRCA1 is a component of the BRG1 complex, suggesting that alterations in BRG1 function predispose individuals to breast and ovarian cancer. Furthermore, mutations in the INI 1 subunit of the BRM complex have been identified in malignant rhabdoid tumors. Thus, the information gained from the study of chromatin remodeling factors in Drosophila should be directly relevant to human disease.