Trps1 Haploinsufficiency Promotes Renal Fibrosis by Increasing Arkadia Expression
Trps1 Haploinsufficiency Promotes Renal Fibrosis by Increasing Arkadia Expression
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DOI：
10.1681/asn.2009121201
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发表时间：
2010-09-01
影响因子：
13.6
通讯作者：
Muragaki, Yasuteru
中科院分区：
文献类型：
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作者：
Gai, Zhibo;Zhou, Gengyin;Muragaki, Yasuteru
TRPS 1突变导致鼻咽综合征（TRPS）。Trps 1是肾单位发育所必需的，作用于Bmp 7的下游。由于Bmp 7抵消上皮间质转化（EMT）和逆转慢性肾损伤，我们研究了Trps 1在肾纤维化中的功能。免疫组化显示Trps 1在小鼠近端肾小管上皮细胞中表达。单侧输尿管梗阻降低野生型和杂合Trps 1基因敲除（Trps 1（+/-））小鼠Trps 1的mRNA和蛋白表达。Trps 1单倍不足通过增加Smad 3的磷酸化和减少Smad 7蛋白促进肾小管间质纤维化。在原代培养中，Trps 1缺陷促进近曲小管细胞中TGF-β 1介导的EMT。Trps 1（+/-）衍生的细胞具有更高水平的磷酸化Smad 3，TGF-β 1诱导野生型和Trps 1（+/-）肾脏中Smad 7蛋白的时间依赖性降低。此外，与野生型细胞相比，Trps 1（+/-）细胞具有两倍的E3泛素连接酶Arkadia的量，并且TGF-β 1诱导进一步的Arkadia表达。此外，Arkadia的敲低抑制了Trps 1（+/-）细胞中TGF-β 1诱导的EMT。总的来说，这些数据表明，Trps 1单倍不足增强TGF-β 1诱导的EMT和肾小管间质纤维化通过调节Smad 7的量通过Arkadia/泛素介导的降解。
Mutations in TRPS1 cause tricho-rhino-pharyngeal syndrome (TRPS). Trps1 is essential for nephron development, acting downstream of Bmp7. Because Bmp7 counteracts epithelial-to-mesenchymal transition (EMT) and reverses chronic renal injury, we examined the function of Trps1 in renal fibrosis. Immunohistochemistry revealed Trps1 expression in proximal tubular epithelial cells of mice. Unilateral ureteral obstruction reduced mRNA and protein expression of Trps1 in wild-type and heterozygous Trps1-knockout (Trps1(+/-)) mice. Trps1 haploinsufficiency promoted tubulointerstitial fibrosis via increased phosphorylation of Smad3 and decreased Smad7 protein. In primary culture, Trps1 deficiency promoted TGF-beta 1-mediated EMT in proximal tubule cells. Trps1(+/-)-derived cells had higher levels of phosphorylated Smad3, and TGF-beta 1 induced a time-dependent decrease in Smad7 protein in wild-type and Trps1(+/-) kidneys. In addition, compared with wild-type cells, Trps1(+/-) cells had double the amount of the E3 ubiquitin ligase Arkadia, and TGF-beta 1 induced further Arkadia expression. Furthermore, knockdown of Arkadia inhibited TGF-beta 1-induced EMT in Trps1(+/-) cells. Collectively, these data suggest that Trps1 haploinsufficiency enhances TGF-beta 1-induced EMT and tubulointerstitial fibrosis by modulating the amount of Smad7 through Arkadia/ubiquitin-mediated degradation.