Thrombin stimulates proliferation of cultured rat aortic smooth muscle cells by a proteolytically activated receptor

• Published in: The Journal of clinical investigation Vol. 91; no. 1; pp. 94 - 98
• Main Authors: MCNAMARA, C. A, SAREMBOCK, I. J, GIMPLE, L. W, FENTON, J. W, COUGHLIN, S. R, OWENS, G. K
• Format: Journal Article
• Language: English
• Published: Ann Arbor, MI American Society for Clinical Investigation 1993
• Subjects: Amino Acid Sequence; Animals; Aorta - cytology; Aorta - drug effects; Biological and medical sciences; Cardiology. Vascular system; Cell Division - drug effects; Cells, Cultured; DNA - biosynthesis; DNA Probes; Dose-Response Relationship, Drug; Femoral Artery - cytology; Femoral Artery - drug effects; Heart; Heart failure, cardiogenic pulmonary edema, cardiac enlargement; Hirudins - pharmacology; Humans; Kinetics; Medical sciences; Molecular Sequence Data; Muscle, Smooth, Vascular - cytology; Muscle, Smooth, Vascular - drug effects; Muscle, Smooth, Vascular - metabolism; Peptide Fragments - pharmacology; Rabbits; Rats; Receptors, Cell Surface - drug effects; Receptors, Cell Surface - genetics; Receptors, Cell Surface - physiology; Receptors, Thrombin; Recombinant Proteins - pharmacology; RNA, Messenger - metabolism; Thrombin - antagonists & inhibitors; Thrombin - pharmacology; Thymidine - metabolism; Arteriopathy; Animal model; Vertebrata; Mammalia; Rat; Animal; Rodentia; Stenosis; Cardiovascular disease; Aortic disease
• ISSN: 0021-9738; 1558-8238
• DOI: 10.1172/jci116206

Thrombin has been implicated in the stimulation of smooth muscle cell (SMC) proliferation that contributes to post angioplasty restenosis. The present studies demonstrated that human alpha-thrombin was a potent and efficacious mitogen for cultured rat aortic SMC, stimulating an increase in 3H-thymidine incorporation, as well as an increase in cell number at 1 to 10 nM concentration. gamma-Thrombin, which is enzymatically active but lacks fibrinogen clotting activity, stimulated SMC mitogenesis but was approximately 10-fold less potent than alpha-thrombin. In contrast, D-phenylalanyl-L-propyl-L-arginyl-chloromethyl ketone-alpha-thrombin, which lacked enzymatic activity, had no mitogenic effect. Diisopropylfluorophosphate-alpha-thrombin failed to stimulate mitogenesis except at concentrations having equivalent enzymatic activity as that of alpha-thrombin at its threshold for mitogenesis. Thus, thrombin-induced proliferation was dependent on enzymatic activity. A 14-residue peptide (SFLLRNPNDKYEPF) corresponding to amino acids 42 through 55 of the human thrombin receptor (Vu, T. K., D. T. Hung, V. I. Wheaton, and S. R. Coughlin, 1991. Cell. 64:1057-1068) had full efficacy in stimulating SMC proliferation. Reversing the first two amino acids of this peptide abolished mitogenic activity. Northern analysis demonstrated that SMC expressed a single mRNA species that hybridized to a labeled thrombin receptor cDNA probe. These findings indicate that alpha-thrombin stimulates SMC proliferation via the proteolytic activation of a receptor very similar or identical to that previously identified.