ROLE OF P270 IN DIFFERENTIATION AND TUMORIGENESIS

描述（申请人的描述）：最近分离的果蝇属和 许多酵母SWI/SNF复合体成员的哺乳动物同源物表明， 这些复合物在所有生物体的细胞生长和发育过程中对基因表达的调节起重要作用。这些蛋白质中的一些的改变与致瘤表型相关。在癌细胞系C33和SW 13中已经证明了人SWI 2同源物Brg 1和hBrm的缺失。在恶性横纹肌样瘤中发现hSNF 5/INI 1基因的双等位基因改变。p270是人类SWI/SNF复合物的组成成员，首次在我的实验室通过其与p300和CBP共享的抗原特异性而被鉴定。序列分析 提示p270是SWI 1的哺乳动物同源物。p270在SWI/SNF复合物中的功能尚不清楚，但某些基序提供了线索。p270含有四个LXXLL基序，被证明与核激素受体结合。 p270还包含最近定义的ARID（AT丰富的相互作用结构域）DNA结合共有序列。p270的这些区域及其在SWI/SNF复合物中的位置，似乎介导组织特异性基因表达， 包含染色质重塑活性，提示p270作为激素信号传导和转录起始的整合剂的潜在功能。p270的这种潜在功能表明它将在细胞驱动的分化中发挥重要作用。 本研究拟从p270的结构与功能关系入手，重点探讨p270的LXXLL基序及其在核转录调控中的作用。 分化过程中的激素信号传导，重点是糖皮质激素驱动的脂肪细胞分化。具体而言，我建议：鉴定p270中LXXLL基序介导的蛋白质相互作用;确定激素对p270活性和表达的影响;并确定是否 p270有助于细胞生长控制。

DESCRIPTION (Applicant's Description): Recent isolation of Drosophila and mammalian homologs of many of the yeast SWI/SNF complex members suggest that these complexes play fundamental roles in the regulation of gene expression during cell growth and development in all organisms. Alterations in some of these proteins have been associated with the tumorigenic phenotype. Loss of the human SWI2 homologs Brg1 and hBrm have been demonstrated in the cancer cell lines C33 and SW13. Biallelic alterations of the hSNF5/INI1 gene were discovered in malignant rhabdoid tumors. p270 is an integral member of human SWI/SNF complexes, first identified in my lab through its shared antigenic specificity with p300 and CBP. Sequence analysis of p270 suggests it is the mammalian homolog of SWI1. The function of p270 in the SWI/SNF complex is not known, but certain motifs provide a clue. p270 contains four LXXLL motifs demonstrated to bind nuclear hormone receptors. p270 also contains a recently defined ARID (AT-Rich Interaction Domain) DNA binding consensus sequence. These regions of p270 and its location in the SWI/SNF complex, which appears to mediate tissue specific gene expression and to contain chromatin remodeling activities, suggest a potential function for p270 as an integrator of hormone signaling and transcription initiation. This potential function of p270 suggests it will play an important role in hormonally driven differentiation. I propose to study the structure and function relationship of p270 with a focus on the roles of the LXXLL motifs and activity of the protein on nuclear hormone signaling during differentiation, with an emphasis on glucocorticoid driven adipocyte differentiation. Specifically I propose to: identify the protein interactions mediated by the LXXLL motifs in p270; determine the effect of hormones on activity and expression of p270; and determine whether p270 contributes to cell growth control.