Id3 Is a Direct Transcriptional Target of Pax7 in Quiescent Satellite Cells
Id3 Is a Direct Transcriptional Target of Pax7 in Quiescent Satellite Cells
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DOI：
10.1091/mbc.e08-12-1185
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发表时间：
2009-07-15
影响因子：
3.3
通讯作者：
Lassar, Andrew B.
中科院分区：
文献类型：
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作者：
Kumar, Deepak;Shadrach, Jennifer L.;Lassar, Andrew B.
Pax7 是骨骼肌干细胞的关键调节因子，需要与 Pax3 一起生成骨骼肌前体细胞。我们在 C2C12 肌肉细胞中鉴定了一系列由 Pax3 或 Pax7 诱导的基因。两个值得注意的 Pax3/7 靶标是 DNA 结合 (Id) 2 和 Id3 的抑制性螺旋-环-螺旋 (HLH) 蛋白抑制剂，两者均在静止卫星细胞中与 Pax7 协同表达，并在 Pax3 或 Pax7 异位表达后在静止 C2C12 肌原细胞中被诱导。异位 Pax7 激活由 Id3 启动子驱动的荧光素酶报告基因的表达，并且该报告基因的最大诱导需要位于 Id3 基因上游的保守 Pax7 结合位点。染色质免疫沉淀表明 Pax7 在静止卫星细胞中结合在 Id3 启动子的上游。此外，在培养的卫星细胞中，短发夹 RNA 介导的 Pax7 表达敲低同时降低了 Id2 和 Id3 的表达。总之，这些发现表明，Id3 是静止卫星细胞中 Pax7 的直接转录靶标，并且表明 Pax7 通过诱导 Id2 和 Id3 的表达来阻止静止卫星细胞的过早分化，而 Id2 和 Id3 反过来可能会阻止肌源性碱性 (b) HLH 蛋白的早熟诱导和/或肌源性 bHLH 蛋白的活性。
Pax7 is a key regulator of skeletal muscle stem cells and is required along with Pax3 to generate skeletal muscle precursors. We have identified a collection of genes induced by either Pax3 or Pax7 in C2C12 muscle cells. Two notable Pax3/7 targets are the inhibitory helix-loop-helix (HLH) proteins inhibitor of DNA binding (Id) 2 and Id3, both of which are coordinately expressed with Pax7 in quiescent satellite cells and are induced in quiescent C2C12 myogenic cells after ectopic expression of either Pax3 or Pax7. Ectopic Pax7 activates expression of a luciferase reporter driven by the Id3 promoter, and maximal induction of this reporter requires a conserved Pax7 binding site located upstream of the Id3 gene. Chromatin immunoprecipitation indicated that Pax7 is bound upstream of the Id3 promoter in quiescent satellite cells. In addition, short hairpin RNA-mediated knockdown of Pax7 expression in cultured satellite cells coordinately decreased both Id2 and Id3 expression. Together, these findings indicate that Id3 is a direct transcriptional target for Pax7 in quiescent satellite cells, and they suggest that Pax7 acts to block premature differentiation of quiescent satellite cells by inducing the expression of Id2 and Id3, which in turn may act to block either the precocious induction of myogenic basic (b) HLH proteins, the activity of myogenic bHLH proteins, or both.