A novel genetic hierarchy functions during hypaxial myogenesis:: Pax3 directly activates Myf5 in muscle progenitor cells in the limb
A novel genetic hierarchy functions during hypaxial myogenesis:: Pax3 directly activates Myf5 in muscle progenitor cells in the limb
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DOI：
10.1101/gad.382806
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发表时间：
2006-09-01
影响因子：
10.5
通讯作者：
Buckingham, Margaret E.
中科院分区：
文献类型：
--
作者：
Bajard, Lola;Relaix, Frederic;Buckingham, Margaret E.
我们讨论了源自下轴体的祖细胞中肌发生的分子控制。骨骼肌形成的关键调控因子Pax3的零突变导致该区域的细胞死亡。我们已经开发了一个新的Pax3等位基因，编码一个Pax3嵌入的融合蛋白，作为转录抑制因子。杂合子小鼠胚胎具有弱突变表型，下轴体及其肌源性衍生物（包括一些后肢肌肉）部分保存。在这些位点，Myf5的表达受到损害，表明Pax3在这个肌生成决定基因的遗传上游起作用。我们发现了一个145碱基对（bp）的调控元件，位于Myf5的-57.5 kb处，它将转基因表达引导到成熟体，特别是形成腹侧躯干和肢体肌肉的下轴结构域的肌源性细胞。该序列中的一个Pax3共识位点在体外和体内结合Pax3。145 bp序列的多片段直接表达到Pax3的功能位点，并且在鸡胚中对其活性的测定显示出Pax3依赖性。Pax3位点的突变消除了转基因小鼠胚胎中145-bp序列控制的所有表达。我们得出结论，Pax3直接调控下轴体及其衍生物中的Myf5。
We address the molecular control of myogenesis in progenitor cells derived from the hypaxial somite. Null mutations in Pax3, a key regulator of skeletal muscle formation, lead to cell death in this domain. We have developed a novel allele of Pax3 encoding a Pax3-engrailed fusion protein that acts as a transcriptional repressor. Heterozygote mouse embryos have an attenuated mutant phenotype, with partial conservation of the hypaxial somite and its myogenic derivatives, including some hindlimb muscles. At these sites, expression of Myf5 is compromised, showing that Pax3 acts genetically upstream of this myogenic determination gene. We have characterized a 145-base-pair (bp) regulatory element, at -57.5 kb from Myf5, that directs transgene expression to the mature somite, notably to myogenic cells of the hypaxial domain that form ventral trunk and limb muscles. A Pax3 consensus site in this sequence binds Pax3 in vitro and in vivo. Multimers of the 145-bp sequence direct transgene expression to sites of Pax3 function, and an assay of its activity in the chick embryo shows Pax3 dependence. Mutation of the Pax3 site abolishes all expression controlled by the 145-bp sequence in transgenic mouse embryos. We conclude that Pax3 directly regulates Myf5 in the hypaxial somite and its derivatives.