Vascular endothelial growth factor modulates skeletal myoblast function.
Vascular endothelial growth factor (VEGF) expression is enhanced in ischemic skeletal muscle and is thought to play a key role in the angiogenic response to ischemia. However, it is still unknown whether, in addition to new blood vessel growth, VEGF modulates skeletal muscle cell function. In the present study immunohistochemical analysis showed that, in normoperfused mouse hindlimb, VEGF and its receptors Flk-1 and Flt-1 were expressed mostly in quiescent satellite cells. Unilateral hindlimb ischemia was induced by left femoral artery ligation. At day 3 and day 7 after the induction of ischemia, Flk-1 and Flt-1 were expressed in regenerating muscle fibers and VEGF expression by these fibers was markedly enhanced. Additional in vitro experiments showed that in growing medium both cultured satellite cells and myoblast cell line C2C12 expressed VEGF and its receptors. Under these conditions, Flk-1 receptor exhibited constitutive tyrosine phosphorylation that was increased by VEGF treatment. During myogenic differentiation Flk-1 and Flt-1 were down-regulated. In a modified Boyden Chamber assay, VEGF enhanced C2C12 myoblasts migration approximately fivefold. Moreover, VEGF administration to differentiating C2C12 myoblasts prevented apoptosis, while inhibition of VEGF signaling either with selective VEGF receptor inhibitors (SU1498 and CB676475) or a neutralizing Flk-1 antibody, enhanced cell death approximately 3.5-fold. Finally, adenovirus-mediated VEGF(165) gene transfer inhibited ischemia-induced apoptosis in skeletal muscle. These results support a role for VEGF in myoblast migration and survival, and suggest a novel autocrine role of VEGF in skeletal muscle repair during ischemia.
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002454:Cell Differentiation / Q000502:physiology; D015687:Cell Hypoxia / Q000502:physiology; D002460:Cell Line; D002465:Cell Movement / Q000502:physiology; D002470:Cell Survival / Q000502:physiology; D016228:Endothelial Growth Factors / Q000494:pharmacology / Q000502:physiology*; D016326:Extracellular Matrix Proteins / Q000378:metabolism; D018014:Gene Transfer Techniques; D006614:Hindlimb; D036341:Intercellular Signaling Peptides and Proteins / Q000494:pharmacology / Q000502:physiology*; D007511:Ischemia / Q000503:physiopathology; D008222:Lymphokines / Q000494:pharmacology / Q000502:physiology*; D008297:Male; D051379:Mice; D008815:Mice, Inbred Strains; D018482:Muscle, Skeletal / Q000098:blood supply / Q000166:cytology* / Q000502:physiology* / Q000503:physiopathology; D032446:Myoblasts / Q000166:cytology / Q000502:physiology*; D018995:Myosin Heavy Chains; D024501:Nonmuscle Myosin Type IIB; D012038:Regeneration; D032496:Satellite Cells, Skeletal Muscle / Q000166:cytology / Q000378:metabolism; D042461:Vascular Endothelial Growth Factor A; D040281:Vascular Endothelial Growth Factor Receptor-1; D040301:Vascular Endothelial Growth Factor Receptor-2 / Q000378:metabolism; D042442:Vascular Endothelial Growth Factors
D016228:Endothelial Growth Factors; D016326:Extracellular Matrix Proteins; D036341:Intercellular Signaling Peptides and Proteins; D008222:Lymphokines; C467484:VEGFA protein, human; D042461:Vascular Endothelial Growth Factor A; D042442:Vascular Endothelial Growth Factors; C501162:FLT1 protein, human; C501163:Flt1 protein, mouse; D040281:Vascular Endothelial Growth Factor Receptor-1; D040301:Vascular Endothelial Growth Factor Receptor-2; D024501:Nonmuscle Myosin Type IIB; C103815:nonmuscle myosin type IIB heavy chain; D018995:Myosin Heavy Chains