XB-ART-38842Dev Dyn November 1, 2008; 237 (11): 3373-86.
Induction and modulation of smooth muscle differentiation in Xenopus embryonic cells.
By comparison with skeletal or cardiac developmental programs, little is known regarding the specific factors that promote specification and differentiation of smooth muscle cells from pluripotent cells. We have analyzed the developmental expression of a subset of smooth muscle genes during Xenopus early development and showed that similar to mammals and avians, Xenopus smooth muscle myosin heavy chain (SM-MHC) is a highly specific marker of smooth muscle differentiation. Embryonic cells from animal pole explants of Xenopus blastula can be induced by basic fibroblast growth factor, Wnt, and bone morphogenetic protein signals to adopt the smooth muscle pathway. Explants from early embryos that contain neural crest cells can also differentiate into cells expressing smooth muscle genes. We examined the interplay of several transcription factors, that is SRF, myocardin, and GATA6, that induce the expression of SM-MHC in animal cap cells and found that myocardin-dependent expression of smooth muscle genes in animal cap cells is synergized by SRF but is strongly antagonized by GATA6.
PubMed ID: 18855898
Article link: Dev Dyn
Species referenced: Xenopus laevis
Genes referenced: acta2 actl6a gata6 myh11 myh4 myh6 myocd srf
Article Images: [+] show captions
|Figure 4. Spatial expression of SM-MHC and SM alpha -actin in developing embryo. A: Whole-mount in situ hybridization (a,b) and in situ hybridization on cross-sections embryo (c-h) of SM-MHC (a,c,e,g) and SM alpha -actin (b,d,f,h). a: SM-MHC expression in branchial arches (ba) and around the dorsal aorta (da) in stage 38 embryo. b: SM alpha -actin expression in embryonic heart (h) in stage 38 embryo. c-f: SM-MHC and SM alpha -actin expression (arrowheads) in the muscle layer of stage 42 embryonic gut. The squares in c and d indicate higher magnification of the section showed in e and f, respectively. g: SM-MHC expression is detected in cells surrounding the aorta (ao) in stage 46 embryo but not in ventricle (vent) or atrium (atr). h: SM alpha -actin expression in muscle layer of intestine (int) in stage 46 embryo. B: SM alpha -actin expression in cross-section of stage 42 embryo analyzed by immunohistochemistry (a-c) and immunofluorescence (d-f). a: The squares indicate higher magnification of the section showed in b and c, respectively. b: SM alpha -actin expression in muscle layer of the gut (arrowhead). c: SM alpha -actin expression in cells surrounding the dorsal aorta (arrowhead). d: The squares indicate higher magnification of the section showed in e and f, respectively. e: SM alpha -actin expression in the muscle layer of the gut (arrowhead). f: SM alpha -actin expression in the cells surrounding the dorsal aorta (arrowhead).|