整合素介导的II型转化生长因子-β受体酪氨酸去磷酸化控制SMAD依赖的促纤维化信号传导。

Integrin-mediated type II TGF-β receptor tyrosine dephosphorylation controls SMAD-dependent profibrotic signaling.

作者信息

Chen Xiwu, Wang Hongtao, Liao Hong-Jun, Hu Wen, Gewin Leslie, Mernaugh Glenda, Zhang Sheng, Zhang Zhong-Yin, Vega-Montoto Lorenzo, Vanacore Roberto M, Fässler Reinhard, Zent Roy, Pozzi Ambra

出版信息

J Clin Invest. 2014 Aug;124(8):3295-310. doi: 10.1172/JCI71668. Epub 2014 Jul 1.

Abstract

Tubulointerstitial fibrosis underlies all forms of end-stage kidney disease. TGF-β mediates both the development and the progression of kidney fibrosis through binding and activation of the serine/threonine kinase type II TGF-β receptor (TβRII), which in turn promotes a TβRI-mediated SMAD-dependent fibrotic signaling cascade. Autophosphorylation of serine residues within TβRII is considered the principal regulatory mechanism of TβRII-induced signaling; however, there are 5 tyrosine residues within the cytoplasmic tail that could potentially mediate TβRII-dependent SMAD activation. Here, we determined that phosphorylation of tyrosines within the TβRII tail was essential for SMAD-dependent fibrotic signaling within cells of the kidney collecting duct. Conversely, the T cell protein tyrosine phosphatase (TCPTP) dephosphorylated TβRII tail tyrosine residues, resulting in inhibition of TβR-dependent fibrotic signaling. The collagen-binding receptor integrin α1β1 was required for recruitment of TCPTP to the TβRII tail, as mice lacking this integrin exhibited impaired TCPTP-mediated tyrosine dephosphorylation of TβRII that led to severe fibrosis in a unilateral ureteral obstruction model of renal fibrosis. Together, these findings uncover a crosstalk between integrin α1β1 and TβRII that is essential for TβRII-mediated SMAD activation and fibrotic signaling pathways.

摘要

肾小管间质纤维化是所有终末期肾病的共同病理基础。转化生长因子-β(TGF-β)通过与II型丝氨酸/苏氨酸激酶TGF-β受体(TβRII)结合并激活,介导肾脏纤维化的发生和发展,进而促进TβRI介导的SMAD依赖性纤维化信号级联反应。TβRII内丝氨酸残基的自磷酸化被认为是TβRII诱导信号传导的主要调节机制;然而,其胞质尾内有5个酪氨酸残基可能介导TβRII依赖性的SMAD激活。在此,我们确定TβRII尾内酪氨酸的磷酸化对于肾集合管细胞内SMAD依赖性纤维化信号传导至关重要。相反,T细胞蛋白酪氨酸磷酸酶(TCPTP)使TβRII尾酪氨酸残基去磷酸化,从而抑制TβR依赖性纤维化信号传导。胶原结合受体整合素α1β1是将TCPTP募集到TβRII尾所必需的,因为缺乏这种整合素的小鼠在单侧输尿管梗阻性肾纤维化模型中表现出TCPTP介导的TβRII酪氨酸去磷酸化受损,进而导致严重纤维化。这些发现共同揭示了整合素α1β1与TβRII之间的相互作用,这对于TβRII介导的SMAD激活和纤维化信号通路至关重要。

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