Hepatocyte growth factor (HGF) inhibits skeletal muscle cell differentiation: a role for the bHLH protein twist and the cdk inhibitor p27.
Hepatocyte growth factor (HGF) plays a crucial role in regulating the differentiation of both fetal and adult skeletal myoblasts. This study aimed at defining the intracellular factors that mediate the effect of HGF on adult myoblast differentiation. HGF increased Twist expression while decreasing p27(kip1) protein levels and not affecting the induction of p21(Cip1/Waf1) in satellite cells. Like HGF, overexpression of Twist did not affect p21 expression while inhibiting muscle-specific proteins. Both ectopic Twist-antisense (Twist-AS) and p27 partially rescued the effects of HGF on bromodeoxyuridine (BrdU) incorporation and myosin heavy chain (MHC) expression in muscle satellite cells; the two plasmids together effected full rescue, suggesting that HGF independently regulates these two factors to mediate its effects. Ectopic p27 promoted differentiation in the presence of HGF by blocking the induction of Twist. Using Twist-AS to lower Twist levels restored the HGF-dependent reduction of p27 and MHC. In the presence of ectopic HGF, satellite cells formed thin mononuclear myotubes. Neither ectopic p27, Twist-AS, or their combination reversed this change in cell morphology, suggesting that HGF acts through additional mediators to inhibit downstream events during myogenesis. Taken together, the results suggest that the effects of HGF on muscle cell proliferation and differentiation are mediated through changes in the expression levels of the myogenic-inhibitory basic helix-loop-helix (bHLH) protein Twist and the cell-cycle inhibitor p27.
Leshem
Y
Y
Department of Animal Sciences, The Hebrew University of Jerusalem, Rehovot, Israel.
Spicer
D B
DB
Gal-Levi
R
R
Halevy
O
O
D000818:Animals; D018797:Cell Cycle Proteins; D002454:Cell Differentiation / Q000187:drug effects*; D002460:Cell Line; D002478:Cells, Cultured; D002645:Chickens; D050760:Cyclin-Dependent Kinase Inhibitor p27; D018844:Cyclin-Dependent Kinases / Q000037:antagonists & inhibitors; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D005786:Gene Expression Regulation; D018257:Helix-Loop-Helix Motifs; D017228:Hepatocyte Growth Factor / Q000737:chemistry / Q000494:pharmacology*; D064326:MEF2 Transcription Factors; D051379:Mice; D008869:Microtubule-Associated Proteins / Q000235:genetics / Q000502:physiology*; D018482:Muscle, Skeletal / Q000166:cytology* / Q000502:physiology*; D018006:Myogenic Regulatory Factors; D018995:Myosin Heavy Chains / Q000235:genetics*; D014157:Transcription Factors / Q000235:genetics; D014162:Transfection; D025521:Tumor Suppressor Proteins
C493961:Cdkn1b protein, mouse; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D064326:MEF2 Transcription Factors; D008869:Microtubule-Associated Proteins; D018006:Myogenic Regulatory Factors; D014157:Transcription Factors; D025521:Tumor Suppressor Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; D017228:Hepatocyte Growth Factor; D018844:Cyclin-Dependent Kinases; D018995:Myosin Heavy Chains