Endothelial cell-conditioned medium downregulates smooth muscle contractile protein expression.
Smooth muscle cells (SMC) within atherosclerotic lesions proliferate and exhibit phenotypic modulation, but the contribution of vascular endothelium to this process is poorly understood. Our aim was to examine the effects of endothelial cell-conditioned medium (ECCM) on vascular SMC growth and differentiation. Rat aortic ECCM stimulated a ninefold increase in [3H]thymidine incorporation and downregulated smooth muscle-specific myosin heavy chain and alpha-actin synthesis in rat aortic SMC. These effects were not inhibited by antibodies to platelet-derived growth factor (PDGF)-BB or PDGF-AB or with a PDGF beta-receptor subunit. Treatment with PDGF-BB (at a concentration found in ECCM), PDGF-AA, basic fibroblast growth factor, endothelin-1, or transforming growth factor-beta did not reproduce these effects. The ECCM activities were sensitive to heat and trypsinization, were >30 kDa in molecular mass, and bound weakly to heparin-Sepharose. Our data indicate that cultured endothelial cells produce a factor(s) that downregulates contractile protein expression in SMC, which may contribute to SMC dedifferentiation and proliferation.
Vernon
S M
SM
Department of Medicine (Cardiology), University of Virginia School of Medicine, Charlottesville 22908, USA.
Campos
M J
MJ
Haystead
T
T
Thompson
M M
MM
DiCorleto
P E
PE
Owens
G K
GK
D000199:Actins / Q000378:metabolism; D000818:Animals; D000906:Antibodies / Q000276:immunology / Q000494:pharmacology; D000077214:Becaplermin; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D003285:Contractile Proteins / Q000378:metabolism*; D017077:Culture Media, Conditioned / Q000378:metabolism / Q000494:pharmacology*; D004730:Endothelium, Vascular / Q000166:cytology / Q000502:physiology*; D006493:Heparin / Q000378:metabolism; D006358:Hot Temperature; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism*; D018995:Myosin Heavy Chains / Q000378:metabolism; D010446:Peptide Fragments / Q000494:pharmacology; D010982:Platelet-Derived Growth Factor / Q000276:immunology; D020574:Proto-Oncogene Proteins c-sis; D051381:Rats; D017207:Rats, Sprague-Dawley; D020797:Receptor, Platelet-Derived Growth Factor beta; D017479:Receptors, Platelet-Derived Growth Factor / Q000737:chemistry; D014357:Trypsin / Q000494:pharmacology
D000199:Actins; D000906:Antibodies; D003285:Contractile Proteins; D017077:Culture Media, Conditioned; D010446:Peptide Fragments; D010982:Platelet-Derived Growth Factor; D020574:Proto-Oncogene Proteins c-sis; D000077214:Becaplermin; D006493:Heparin; D020797:Receptor, Platelet-Derived Growth Factor beta; D017479:Receptors, Platelet-Derived Growth Factor; D014357:Trypsin; D018995:Myosin Heavy Chains