A GENE WITH HOMOLOGY TO THE MYC SIMILARITY REGION OF MYOD1 IS EXPRESSED DURING MYOGENESIS AND IS SUFFICIENT TO ACTIVATE THE MUSCLE DIFFERENTIATION PROGRAM
A GENE WITH HOMOLOGY TO THE MYC SIMILARITY REGION OF MYOD1 IS EXPRESSED DURING MYOGENESIS AND IS SUFFICIENT TO ACTIVATE THE MUSCLE DIFFERENTIATION PROGRAM
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DOI：
10.1101/gad.3.5.628
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发表时间：
1989-05-01
影响因子：
10.5
通讯作者：
OLSON, EN
中科院分区：
文献类型：
--
作者：
EDMONDSON, DG;OLSON, EN
MyoD1是一种核蛋白，在体内表达于骨骼肌中，在体外表达于某些肌肉细胞系中；已被证明通过一种需要与myc家族蛋白同源的结构域的机制将成纤维细胞转化为成肌细胞。BC3H1肌肉细胞系在暴露于丝裂原缺乏的介质中时表达骨骼肌特异基因，但不表达可检测到的MyoD1。为了确定BC3H1细胞是否可能表达与MyoD1功能相关的调控基因，从分化的BC3H1心肌细胞中制备了一个与MyoD1c同源的cDNA文库，并对其进行了严格程度的降低。从这一筛选中鉴定出一个编码一个主要开放阅读框架的cDNA，它与MyoD1的myc结构域和碱性区域有72%的同源性。该基因编码的mRNA在体内骨骼肌和体外分化的骨骼肌细胞中均有表达，在心肌或平滑肌、非肌肉组织、非肌源性细胞中检测不到。在肌肉发生过程中，MyoD1处理的mRNA比其他肌肉特异的mRNAs早几个小时积累，因此是成肌细胞进入分化途径的早期分子标志物。将MyoD1相关基因瞬时导入10T1/2或3T3细胞，足以诱导肌球蛋白重链表达，并激活肌酸激酶5‘增强子转录控制下的报告基因，该增强子仅在分化的心肌细胞中起作用。该基因在稳定表达的10T1/2细胞中的表达，在缺乏丝裂原的培养液中也能导致融合和肌肉特异性基因的表达。因此，这种MyoD1相关基因的产物足以激活肌肉分化程序，并可能在某些发育情况下替代MyoD1。综上所述，这些结果表明存在一个与HC-myc共有保守基序的生肌调节基因家族。
MyoD1 is a nuclear phosphorprotein that is expressed in skeletal muscle in vivo and in certain muscle cell lines in vitro; it has been shown to convert fibroblasts to myoblasts through a mechanism requiring a domain with homology to the myc family of proteins. The BC3H1 muscle cell line expresses skeletal muscle-specific genes upon exposure to mitogen-deficient medium, but does not express MyoD1 at detectable levels. To determine whether BC3H1 cells may express regulatory genes functionally related to MyoD1, a cDNA library prepared from differentiated BC3 H1 myocytes, was screened at reduced stringency with the region of the MyoD1 cDNA that shares homology with c-myc. From this screen, a cDNA was identified that encodes a major open reading frame with 72% homology to the myc domain and basic region of MyoD1. The mRNA encoded by this MyoD1-related gene is expressed in skeletal muscle in vivo and in differentiated skeletal myocytes in vitro and is undetectable in cardiac or smooth muscle, nonmuscle tissues, nonmyogenic cell types. During myogenesis, the MyoD1-treated mRNA accumulates several hours prior to other muscle-specific mRNAs and therefore represents an early molecular marker for entry of myoblasts into the differentiation pathway. Transient transfection of 10T1/2 or 3T3 cells with the MyoD1-related cDNA is sufficient to induce myosin heavy-chain expression and to activate a reporter gene under transcriptional control of the muscle creatine kinase 5'' enhancer, which functions only in differentiated myocytes. Expression of this cDNA in stably transfected 10T1/2 cells also leads to fusion and muscle-specific gene expression upon exposure to mitogen-deficient medium. Thus, the product of this MyoD1-related gene is sufficient to activate the muscle differentiation program and may substitute for MyoD1 in certain developmental situations. Together, these results suggest the existence of a family of myogenic regulatory genes that share a conserved motif with hc-myc.