Warkman Andrew S, Yatskievych Tatiana A, Hardy Katharine M, Krieg Paul A, Antin Parker B
Department of Cell Biology and Anatomy, University of Arizona, Tucson, Arizona, USA.
Dev Dyn. 2008 Jan;237(1):216-21. doi: 10.1002/dvdy.21393.
Myocardin, a serum response factor cofactor, plays an important role in regulating heart and smooth muscle development. To investigate myocardin function during early stages of heart development, we isolated the chicken orthologue of myocardin and characterized its expression between Hamburger and Hamilton stages 3 and 15. At stage 4, myocardin transcripts are detected in the lateral and extraembryonic mesoderm, become progressively localized to the precardiac mesoderm and the differentiated myocardium and are also seen in smooth muscle cells of the developing vascular plexus. Surprisingly, myocardin expression within the developing chicken embryo precedes that of the homeodomain transcription factor Nkx2.5. Embryonic dissection studies demonstrate that signals from the endoderm are required for myocardin expression within the precardiac mesoderm. However, unlike Nkx2.5, myocardin expression is not regulated by bone morphogenetic protein (BMP) signaling. These results suggest that initial expression of myocardin in the precardiac mesoderm is regulated by a signaling pathway that is parallel to, and independent of, Nkx2.5 expression.
心肌素是一种血清反应因子辅因子，在调节心脏和平滑肌发育中发挥重要作用。为了研究心肌素在心脏发育早期阶段的功能，我们分离了鸡的心肌素直系同源物，并对其在汉伯格和汉密尔顿第3至15阶段的表达进行了表征。在第4阶段，心肌素转录本在外侧和胚外中胚层中被检测到，逐渐定位于心脏前中胚层和分化的心肌，并且在发育中的血管丛的平滑肌细胞中也可见。令人惊讶的是，心肌素在发育中的鸡胚内的表达先于同源结构域转录因子Nkx2.5。胚胎解剖研究表明，内胚层的信号是心脏前中胚层中心肌素表达所必需的。然而，与Nkx2.5不同，心肌素的表达不受骨形态发生蛋白（BMP）信号通路的调节。这些结果表明，心脏前中胚层中心肌素的初始表达受一条与Nkx2.5表达平行且独立的信号通路调控。
