Maeda Tomoji, Gupta Mahesh P, Stewart Alexandre F R
Cardiovascular Institute, School of Medicine, University of Pittsburgh, BST 1704.3, PA 15213, USA.
Biochem Biophys Res Commun. 2002 Jun 21;294(4):791-7. doi: 10.1016/S0006-291X(02)00556-9.
Many muscle-specific genes are regulated by transcriptional enhancer factor-1 (TEF-1), serum response factor (SRF), and myocyte enhancer factor-2 (MEF2) transcription factors. TEF-1 interacts with the MADS domain of SRF and together SRF and TEF-1 co-activate the skeletal alpha-actin promoter. MEF2 factors also contain a MADS domain with 50% amino acid identity to the SRF MADS domain. Because of this sequence divergence, some SRF co-factors do not interact with MEF2. To demonstrate that TEF-1 factors could also interact with MEF2 through its MADS domain, we used co-immunoprecipitation and GST pull-down assays in vitro and a mammalian two-hybrid assay in vivo. The MADS domain was not sufficient for MEF2 interaction with TEF-1, because additional sequences in the activation domains of both proteins were required for in vivo association. The physiological significance of this interaction was also demonstrated by transient transfection assays using muscle-specific promoters. Our results suggest that by their interaction with MEF2 factors, TEF-1 factors can control MEF2-dependent muscle-specific gene expression.
许多肌肉特异性基因受转录增强因子1（TEF-1）、血清反应因子（SRF）和肌细胞增强因子2（MEF2）转录因子调控。TEF-1与SRF的MADS结构域相互作用，SRF和TEF-1共同激活骨骼肌α-肌动蛋白启动子。MEF2因子也含有一个MADS结构域，与SRF的MADS结构域有50%的氨基酸同源性。由于这种序列差异，一些SRF辅助因子不与MEF2相互作用。为了证明TEF-1因子也能通过其MADS结构域与MEF2相互作用，我们在体外使用了免疫共沉淀和GST下拉实验，在体内使用了哺乳动物双杂交实验。MADS结构域不足以使MEF2与TEF-1相互作用，因为两种蛋白激活结构域中的额外序列对于体内结合是必需的。使用肌肉特异性启动子的瞬时转染实验也证明了这种相互作用的生理意义。我们的结果表明，通过与MEF2因子相互作用，TEF-1因子可以控制MEF2依赖性肌肉特异性基因表达。
