XB-IMG-81089
Xenbase Image ID: 81089
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Fig. 4. Myocardin induces transcription of endogenous cardiac and
smooth muscle marker genes in animal cap explants. Myocardinexpressing
animal pole explants were cultured until stage 12.5 and
assayed for cardiac and smooth muscle gene expression by RT-PCR.
(A) Uninjected animal caps differentiate into epidermal tissue and
never express mesodermal derivatives, including cardiac or smooth
muscle markers (lane labeled uninjected). Myocardin-injected caps
however, express a wide range of cardiac and smooth muscle
differentiation markers (lane labeled myocardin), including cardiac
α-actin, MHCα, cardiac TnI, SM22, calponin H1 and smooth muscle
actin. The myocardin cofactor SRF and the MADS box transcription
factor Mef2a, are upregulated in myocardin expressing caps. The
cardiogenic genes, Nkx2-5 and Gata4 are not expressed in
myocardin-injected animal caps. The lane labeled 12.5 WE,
represents the normal expression of the assayed genes in the whole
embryo at the time that the animal cap explants were assayed. (B)
Myocardin does not activate genes of the skeletal muscle or
mesodermal pathways. Myocardin-injected animal caps were
assayed by RT-PCR for the activation of mesodermal and skeletal
muscle markers. The general mesoderm marker brachyury (Xbra) is
not expressed in myocardin-injected caps. Furthermore, myocardin
does not activate expression of the skeletal muscle transcription
regulators, MyoD, Myf5, MRF4 and myogenin, or the skeletal
muscle-specific differentiation marker skMLC. Image published in: Small EM et al. (2005) Copyright © 2005. Image reproduced with permission of the publisher and the copyright holder. This is an Open Access article distributed under the terms of the Creative Commons Attribution License. Larger Image Printer Friendly View |