Characteristics and expression of transforming growth factor-beta receptor subtypes on vascular smooth muscle cells from spontaneously hypertensive rats.
OBJECTIVE
To investigate the characteristics and expression of transforming growth factor (TGF)-beta receptor subtypes on vascular smooth muscle cells (VSMC) from spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats.


METHODS
The effects of TGF-beta 1 on DNA synthesis were evaluated by [3H]-thymidine incorporation into quiescent VSMC plated at high (5 x 10(4) cells/cm2) or low (5 x 10(3) cells/cm2) cell density. Specific binding of TGF-beta to VSMC was assessed by incubation of the cells with [125I]-TGF-beta 1. Affinity labelling of receptor subtypes was achieved by exposure of the cells to [125I]-TGF-beta 1 and cross-linking with disuccimidyl suberate.


RESULTS
VSMC from SHR displayed a biphasic DNA synthesis response to TGF-beta 1 at high cell density, with DNA synthesis stimulated by low concentrations of TGF-beta 1 but not by high concentrations, whereas at low cell density there was a small increase in DNA synthesis in response to TGF-beta 1. TGF-beta 1 inhibited DNA synthesis in VSMC from WKY rats at both high and low cell densities. Binding assays revealed that VSMC from SHR had a larger number of TGF-beta receptors and a higher affinity for TGF-beta at high and at low cell densities. The affinity labelling with [125I]-TGF-beta 1 revealed the presence of receptor subtypes with relative molecular masses of 280-300, 85, 70, 60 and 50 x 10(3) on vascular smooth muscle cells from both rat strains at high cell density. The abundance of the 85 x 10(3) molecular mass receptor subtype was greater in VSMC from SHR. The 85 x 10(3) molecular mass receptor subtype was not detected on VSMC from either strain at low cell density.


CONCLUSIONS
The present results suggest a different expression of TGF-beta receptor subtypes on VSMC from SHR and WKY rats. These differences may account for the exaggerated proliferative response of VSMC from SHR to TGF-beta.
Fukuda
N
N
Second Department of Internal Medicine, Nihon University School of Medicine, Tokyo, Japan.
Kubo
A
A
Izumi
Y
Y
Soma
M
M
Kanmatsuse
K
K
D000818:Animals; D002478:Cells, Cultured; D004247:DNA / Q000096:biosynthesis; D006973:Hypertension / Q000378:metabolism*; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000378:metabolism*; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY; D018125:Receptors, Transforming Growth Factor beta / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000378:metabolism / Q000494:pharmacology
D018125:Receptors, Transforming Growth Factor beta; D016212:Transforming Growth Factor beta; D004247:DNA