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" Insulin-like growth factors (IGF), IGF binding proteins and myogenic regulatory genes in muscle development "


Document Type : Latin Dissertation
Language of Document : English
Record Number : 1113027
Doc. No : TLpq304129021
Main Entry : C. W. Ernst
: M. E. White
Title & Author : Insulin-like growth factors (IGF), IGF binding proteins and myogenic regulatory genes in muscle development\ C. W. ErnstM. E. White
College : The Ohio State University
Date : 1994
student score : 1994
Degree : Ph.D.
Page No : 287
Abstract : Understanding of the mechanisms involved in skeletal muscle development is essential for increasing efficiency of lean muscle production in livestock species. This project examined the endogenous expression and regulation of two gene families, IGFs and the basic helix-loop-helix (bHLH) family of myogenic regulatory factors, during skeletal muscle development. IGFs stimulate differentiation of myoblasts and IGF binding proteins (IGFBPs) modulate IGF actions, but few studies have considered the role of IGFBPs in muscle. Therefore, two cell culture models (usd\rm C\sb2C\sbusd mouse myoblasts and turkey breast muscle satellite cells) were used to examine the expression of IGF-II and IGFBPs by myoblasts. In both models, relative mRNA abundance and protein secretion of IGFBP-2 was highest in proliferating cultures and decreased markedly with the onset of differentiation. In usd\rm C\sb2C\sbusd cultures, IGF-II mRNA abundance increased during differentiation, whereas in turkey satellite cells, IGF-II was highest in proliferating cells and declined slightly with the onset of differentiation. Relative mRNA abundance of the bHLH factor myogenin was not detected in proliferating turkey satellite cells but increased during differentiation. usd\rm C\sb2C\sbusd cells were used to examine the effects of various hormones on regulation of IGFBP-2 expression. Insulin treatment rapidly decreased IGFBP-2 mRNA abundance and protein secretion, whereas IGF-I and dexamethasone increased IGFBP-2 expression. Prostaglandin usd\rm E\sb2usd increased IGFBP-2 mRNA but did not affect secretion. Growth hormone did not affect IGFBP-2. Genetic variation for the bHLH factors myogenin and myf-6 (MRF4) in pigs was demonstrated using restriction fragment length polymorphism (RFLP) analyses. RFLP patterns for both genes were heritable. The ontogeny of mRNA expression for myogenin and myf-6 in limb muscle of pigs from 60 d of gestation to 49 d of age was also evaluated. Relative mRNA abundance of myogenin decreased during this period, whereas expression of myf-6 increased. These results suggest that myogenin may be more important in prenatal muscle development, whereas myf-6 may play a role in postnatal muscle. These results extend the current knowledge regarding IGF and bHLH myogenic regulatory factor gene families in muscle. It appears that both gene families are intimately involved in the process of skeletal muscle development.
Subject : Biological sciences
copyhttps://lib.clisel.com/site/catalogue/1113027
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