Fukuda N, Kubo A, Izumi Y, Soma M, Kanmatsuse K
Second Department of Internal Medicine, Nihon University School of Medicine, Tokyo, Japan.
J Hypertens. 1995 Aug;13(8):831-7. doi: 10.1097/00004872-199508000-00003.
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.
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.
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.
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.
研究自发性高血压大鼠（SHR）和正常血压的Wistar-Kyoto（WKY）大鼠血管平滑肌细胞（VSMC）上转化生长因子（TGF）-β受体亚型的特征及表达。
通过将[3H]-胸苷掺入以高（5×10⁴个细胞/cm²）或低（5×10³个细胞/cm²）细胞密度接种的静止VSMC中，评估TGF-β1对DNA合成的影响。通过将细胞与[125I]-TGF-β1孵育来评估TGF-β与VSMC的特异性结合。通过将细胞暴露于[125I]-TGF-β1并与辛二酸二琥珀酰亚胺酯交联来实现受体亚型的亲和标记。
SHR的VSMC在高细胞密度下对TGF-β1表现出双相DNA合成反应，低浓度的TGF-β1刺激DNA合成，而高浓度则无此作用，而在低细胞密度下，TGF-β1引起DNA合成略有增加。TGF-β1在高和低细胞密度下均抑制WKY大鼠VSMC中的DNA合成。结合试验显示，SHR的VSMC在高和低细胞密度下具有更多的TGF-β受体且对TGF-β的亲和力更高。用[125I]-TGF-β1进行的亲和标记显示，在高细胞密度下，两种大鼠品系的血管平滑肌细胞上均存在相对分子质量为280 - 300、85、70、60和50×10³的受体亚型。SHR的VSMC中相对分子质量为85×10³的受体亚型丰度更高。在低细胞密度下，两种品系的VSMC上均未检测到相对分子质量为85×10³的受体亚型。
目前的结果表明，SHR和WKY大鼠的VSMC上TGF-β受体亚型的表达不同。这些差异可能解释了SHR的VSMC对TGF-β的过度增殖反应。
