Constitutive endothelin-1 overexpression promotes smooth muscle cell proliferation via an external autocrine loop.
Endothelin-1 (ET-1) is a potent vasoconstrictor peptide originally purified from endothelial cell-conditioned medium. It has multiple biological activities and has been implicated in a number of human diseases, including hypertension and atherosclerosis. Contradictory reports have been published regarding whether ET-1 is a mitogen for vascular smooth muscle cells (SMC); thus, this issue is presently unresolved. In this study, we demonstrate that rat aortic SMC express functional endothelin cell surface receptors but do not proliferate when ET-1 is added to serum-free culture medium on every other day for a period of 1 week. To determine whether ET-1 could function in an autocrine manner to promote SMC growth, we transfected this same cell line with an ET-1 expression plasmid. Several independent lines expressing variable levels of ET-1 mRNA and biologically active ET-1 were obtained. Cell proliferation assays indicated that the transfected SMC line secreting the highest level of ET-1 had an enhanced growth rate when compared with untransfected or vector-alone transfected cells. The growth rate of this SMC line, but not of untransfected cells, was significantly reduced when the ETA receptor subtype-selective antagonist BQ-123 was included in the culture medium. These results indicate that constitutive ET-1 overexpression can promote SMC proliferation. Therefore, it is possible that under certain conditions ET-1 could be an important factor controlling SMC replication in vivo.
Alberts
G F
GF
Department of Molecular Biology, Holland Laboratory, American Red Cross, Rockville, Maryland 20855.
Peifley
K A
KA
Johns
A
A
Kleha
J F
JF
Winkles
J A
JA
D000818:Animals; D001013:Aorta, Thoracic / Q000166:cytology* / Q000187:drug effects; D001483:Base Sequence; D015815:Cell Adhesion Molecules / Q000096:biosynthesis; D002455:Cell Division / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D017931:DNA Primers; D018076:DNA, Complementary / Q000378:metabolism; D016232:Endothelins / Q000096:biosynthesis* / Q000494:pharmacology*; D004730:Endothelium, Vascular / Q000502:physiology*; D015870:Gene Expression / Q000187:drug effects; D016762:Genes, fos / Q000187:drug effects; D006801:Humans; D007700:Kinetics; D008562:Membrane Glycoproteins / Q000096:biosynthesis; D008969:Molecular Sequence Data; D009131:Muscle, Smooth, Vascular / Q000166:cytology* / Q000187:drug effects; D010957:Plasmids; D016133:Polymerase Chain Reaction; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D017466:Receptors, Endothelin / Q000096:biosynthesis / Q000378:metabolism*; D015183:Restriction Mapping; D019699:Thrombospondins; D014158:Transcription, Genetic / Q000187:drug effects; D014162:Transfection; D014471:Umbilical Veins
D015815:Cell Adhesion Molecules; D017931:DNA Primers; D018076:DNA, Complementary; D016232:Endothelins; D008562:Membrane Glycoproteins; D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger; D017466:Receptors, Endothelin; D019699:Thrombospondins