肾上腺髓质素拮抗转化生长因子β_1的促纤维化作用及其机制

The antagonistic effect of adrenomedullin on extracellular matrix accumulation stimulated by transforming growth factor β_1 and the cellular mechanism

目的 :探讨肾上腺髓质素 (AM)在人肾小管上皮细胞系 (HK - 2 )对转化生长因子 β1(TGFβ1)促纤维化作用的影响及机制。方法 :细胞总胶原的合成和分泌以 [3H]-脯氨酸掺入量及培养液内 [3H]-羟脯氨酸放射活性来判断 ;ELISA法检测培养液中纤维连接蛋白 (FN)含量 ;FN、IV型胶原和组织型金属蛋白酶抑制剂 - 1(TIMP - 1)mRNA的表达采用RT -PCR法 ;信号蛋白Smad2及Smad6蛋白表达采用Westernblot法。结果 :( 1)AM在蛋白和mRNA水平均明显抑制TGFβ1刺激的胶原和纤维连结蛋白的表达 ;( 2 )AM抑制TGFβ1刺激的TIMP - 1mRNA的上调 ;( 3 )AM( 10 -8mol/L)本身对Smad2和Smad6的表达无明显影响 ,且对TGFβ1刺激的Smad2的表达也无明显影响 ;但是可以明显上调被TGFβ1抑制的Smad6的表达。结论 :在HK - 2细胞 。

AIM: To investigate the effect of adrenomedullin on the fibrogenic action of TGFβ 1 and the cellular mechanism in renal tubular epithelial cell line (HK-2). METHODS: Total collagen synthesis and secretion were reflected by -proline incorporation and the radioactivity of -hydroproline in the culture medium; ELISA method was used to detect the level of secreted fibronectin (FN); the expression of FN mRNA, collagen IV mRNA and TIMP-1mRNA were determined by RT-PCR; western blot was used to detect the expression of Smad2 and Smad6 proteins. RESULTS: (1) AM could antagonize the expression of collagen and FN stimulated by TGFβ 1 in both transcription and translation level; (2) AM down-regulated the TGFβ 1-induced TIMP-1 mRNA expression; (3) AM had no effect on the over-expression of Smad2 stimulated by TGFβ 1; but could up-regulate the expression of Smad6 inhibited by TGFβ 1. CONCLUSION: AM could antagonize the fibrogenic effect of TGFβ 1 through up-regulating Smad6 expression in HK-2 cell line.