Insulin-like growth factor-II/mannose-6-phosphate receptor expression during early heart development.
Expression of the insulin-like growth factor-II/mannose-6-phosphate (ICF-II/ M6P) receptor was examined during the major stages of heart morphogenesis in the chicken embryo. By using an affinity-purified antibody, Western blot analysis of total embryonic proteins from stages 5-24 revealed little if any IGF-II/M6P receptor protein until stage 7, approximately 8 hours prior to the appearance of the rudimentary myocardial tubes. Thereafter, receptor accumulation increased until stage 14, after which receptor protein levels remained constant, up to 7 days in ovo. Immunohistochemical localization revealed that, among all embryonic tissues at stages 10-24, the predominant site of receptor expression was the developing myocardium. Receptor expression was also immunohistochemically evaluated in a defined in vitro model of cardiogenesis in which explanted precardiac mesoderm is induced to undergo differentiation by co-explanted endoderm. In this system, as in vivo, IGF-II/M6P receptors were only detected after precardiac mesoderm had differentiated into a synchronously contractile multilayer which expressed cardiac alpha-actin. These findings indicate that the IGF-II/M6P receptor has an important role during early heart development.
McCormick
K M
KM
Department of Cellular Biology and Anatomy, Medical College of Wisconsin, Milwaukee 53226, USA.
Dahms
N M
NM
Lough
J
J
D000818:Animals; D015153:Blotting, Western; D002642:Chick Embryo; D019084:Fluorescent Antibody Technique, Indirect; D006321:Heart / Q000196:embryology*; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D017527:Receptor, IGF Type 2 / Q000378:metabolism*
D017527:Receptor, IGF Type 2