L'Honoré Aurore, Coulon Vincent, Marcil Alexandre, Lebel Mélanie, Lafrance-Vanasse Julien, Gage Philip, Camper Sally, Drouin Jacques
Laboratoire de génétique moléculaire, Institut de Recherches Cliniques de Montréal (IRCM), 110, avenue des Pins Ouest, Montréal, QC, Canada H2W 1R7.
Dev Biol. 2007 Jul 15;307(2):421-33. doi: 10.1016/j.ydbio.2007.04.034. Epub 2007 May 3.
The myogenic program is controlled by different groups of transcription factors acting during muscle development, including bHLH muscle regulatory factors (MRFs), the paired factors Pax3 and Pax7 and the homeobox factors Six1 and Six4. This program is critically dependent on MRFs that target downstream muscle-specific genes. We now report the expression of Pitx2 and Pitx3 transcription factors throughout muscle development. Pitx2 is first expressed in muscle progenitor cells of the dermomyotome and myotome. The onset of myoblast differentiation is concomitant with expression of Pitx3; its expression is maintained in all skeletal muscles while Pitx2 expression decreases thereafter. We have generated Pitx3 mutant mice and this deficiency does not significantly perturb muscle development but it is completely compensated by the maintenance of Pitx2 expression in all skeletal muscles. These experiments suggest that Pitx genes are important for myogenesis and that Pitx2 and Pitx3 may have partly redundant roles.
生肌程序受肌肉发育过程中起作用的不同转录因子组控制，包括bHLH肌肉调节因子（MRF）、配对因子Pax3和Pax7以及同源框因子Six1和Six4。该程序严重依赖于靶向下游肌肉特异性基因的MRF。我们现在报告Pitx2和Pitx3转录因子在整个肌肉发育过程中的表达情况。Pitx2首先在皮肌节和肌节的肌肉祖细胞中表达。成肌细胞分化的开始与Pitx3的表达同时发生；其表达在所有骨骼肌中维持，而Pitx2的表达随后下降。我们已经生成了Pitx3突变小鼠，这种缺陷并没有显著扰乱肌肉发育，但所有骨骼肌中Pitx2表达的维持完全补偿了这一缺陷。这些实验表明，Pitx基因对成肌作用很重要，并且Pitx2和Pitx3可能具有部分冗余作用。
