Enhancement of serum-response factor-dependent transcription and DNA binding by the architectural transcription factor HMG-I(Y)
Enhancement of serum-response factor-dependent transcription and DNA binding by the architectural transcription factor HMG-I(Y)
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DOI：
10.1074/jbc.273.16.9755
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发表时间：
1998-04-17
影响因子：
4.8
通讯作者：
Lee, ME
中科院分区：
文献类型：
--
作者：
Chin, MT;Pellacani, A;Lee, ME
HMG-I蛋白调节细胞生长的机制尚不清楚，它们对基因表达的影响也仅得到部分阐明。我们探讨了HMG-I蛋白和血清反应因子（SRF），转录因子的MADS盒家族的成员之间的潜在相互作用。在共转染实验中，HMG-I（Y）增强了两种不同的SRF响应启动子c-fos和平滑肌特异性基因SM 22 α的SRF依赖性激活（超过5倍）。用含有CC（A/T）（6）GG（CArG）盒的多个拷贝的异源启动子也观察到这种效应。在凝胶迁移率变动分析中，HMG-I蛋白特异性结合c-fos和SM 22 α的CArG盒，并增强SRF与这些CArG盒的结合。通过螯合肽固定化金属亲和层析，我们将与SRF相互作用的HMG-I（Y）结构域定位于氨基酸50-81，该区域在电泳迁移率变动分析中不特异性结合DNA，即使它包括第三个AT-钩DNA结合结构域。令人惊讶的是，不能结合DNA的HMG-I（Y）突变体仍然增强SRF与DNA的结合和SRF依赖的转录。相反，缺失结合SRF的HMG-I（I）50-81结构域阻止了转录的增强。据我们所知，这是第一个报告的HMG-I蛋白与MADS盒转录因子相互作用。我们的观察结果表明，HMG-I家族的成员在SRF依赖的转录中起着重要作用，其作用主要是由蛋白质-蛋白质相互作用介导的。
The mechanisms by which HMG-I proteins regulate cell growth are unknown, and their effects on gene expression have only been partially elucidated. We explored the potential interaction between HMG-I proteins and serum-response factor (SRF), a member of the MADS-box family of transcription factors. In cotransfection experiments, HMG-I(Y) potentiated SRF-dependent activation (by more than 5-fold) of two distinct SRF-responsive promoters, c-fos and the smooth muscle-specific gene SM22 alpha. This effect was also observed with a heterologous promoter containing multiple copies of the CC(A/T)(6)GG (CArG) box. HMG-I proteins bound specifically to the CArG boxes of c-fos and SM22 alpha in gel mobility shift analysis and enhanced binding of SRF to these CArG; boxes. By chelating peptide-immobilized metal affinity chromatography, we mapped the domain of HMG-I(Y) that interacts with SRF to amino acids 50-81, a region that does not bind specifically to DNA in electrophoretic mobility shift assays even though it includes the third AT-hook DNA-binding domain. Surprisingly, HMG-I(Y) mutants that failed to bind DNA still enhanced SRF binding to DNA and SRF-dependent transcription. In contrast, deletion of the HMG-I(I) 50-81 domain that bound SRF prevented enhancement of transcription. To our knowledge, this is the first report of an HMG-I protein interacting with a MADS-box transcription factor. Our observations suggest that members of the HMG-I family play an important role in SRF-dependent transcription and that their effect is mediated primarily by a protein-protein interaction.