Smooth muscle-specific transcriptional regulation by SRF and homeodomain proteins

SRF 和同源域蛋白的平滑肌特异性转录调节

基本信息

批准号：
11838010
负责人：
NISHIDA Wataru
金额：
$ 1.41万
依托单位：
Osaka University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
1999
资助国家：
日本
起止时间：
1999 至 2000
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-11838010/
关键词：
Vascular smooth muscle Phenotypic modulation Signal transduction Transcriptional regulation Serum Response Factor Homeodomain proteins GATA transcription factors Serum response factor serum response factor

项目摘要

While serum response factor (SRF)/CArG box interaction has been well documented for a variety of transcription systems, including immediate early and muscle genes, it cannot solely be responsible for transcription in respective tissues. Here, we identified two cis-elements in the alphal-integrin promoter region in addition to CArG box : a TAAT sequence, a consensus-binding site for homeoproteins, and a GATA family-binding box. We further cloned a homeobox cDNA, Nkx-3.2, which is mainly expressed in smooth muscle tissues and skeletal structures. Gel-shift assays showed a ternary complex formation of SRF and Nkx-3.2 or GATA-6 with their corresponding cis-elements. Further, Nkx-3.2, SRF, and GATA-6 or their respective functional domains transactivate synergistically the alphal-integrin gene in vascular SMC-derived cell line and heterologous cells. We conclude that transcription of alphal-integrin in vascular SMCs is regulated by coordinated interactions between Nkx-3.2, SRF, GATA-6 and their corresponding cis-elements. In addition, we characterized the transcriptional machinery of the beta-TM gene in SMCs. Promoter and gel mobility shift analyses revealed an obligatory role for serum response factor (SRF) and its interaction with the CArG box sequence in the SMC-specific transcription of the beta-TM gene in differentiated SMCs. We further isolated a novel homologue of the Barx homeoprotein family, Barx1b, from chicken gizzard. Barx1b was exclusively localized to SMCs of the upper digestive organs and their attached arteries and to craniofacial structures. SRF and Barx1b bound each other directly, coordinately transactivated the beta-TM gene in differentiated SMCs and heterologous cells, and formed a temary complex with a CArG probe. Taken together, these results suggest that SRF, homeodomain proteins, and/or GATA family transcription factors are coordinately involved in the tissue-specific transcription of the smooth muscle genes.

虽然血清反应因子 (SRF)/CArG 盒相互作用已在多种转录系统（包括即早基因和肌肉基因）中得到充分记录，但它不能单独负责各自组织中的转录。在这里，除了 CArG 盒之外，我们还鉴定了 α1 整联蛋白启动子区域中的两个顺式元件：TAAT 序列、同源蛋白的共有结合位点和 GATA 家族结合盒。我们进一步克隆了同源盒cDNA，Nkx-3.2，其主要在平滑肌组织和骨骼结构中表达。凝胶迁移分析显示 SRF 和 Nkx-3.2 或 GATA-6 及其相应的顺式元件形成三元复合物。此外，Nkx-3.2、SRF和GATA-6或它们各自的功能域协同反式激活血管SMC衍生细胞系和异源细胞中的α1整联蛋白基因。我们得出的结论是，血管 SMC 中 α-整合素的转录受到 Nkx-3.2、SRF、GATA-6 及其相应顺式元件之间协调相互作用的调节。此外，我们还描述了 SMC 中 β-TM 基因的转录机制。启动子和凝胶迁移率变化分析揭示了血清反应因子（SRF）的必然作用及其与分化SMC中β-TM基因的SMC特异性转录中的CArG盒序列的相互作用。我们进一步从鸡砂中分离出 Barx 同源蛋白家族的新同源物 Barx1b。 Barx1b 专门定位于上消化器官及其附着动脉以及颅面结构的 SMC。 SRF和Barx1b直接相互结合，协同反式激活分化的SMC和异源细胞中的β-TM基因，并与CArG探针形成三元复合物。综上所述，这些结果表明 SRF、同源域蛋白和/或 GATA 家族转录因子协同参与平滑肌基因的组织特异性转录。