Requirement of mitogen-activated protein kinase kinase 3 (MKK3) for activation of p38α and p38δ MAPK Isoforms by TGF-β1 in murine mesangial cells
Requirement of mitogen-activated protein kinase kinase 3 (MKK3) for activation of p38α and p38δ MAPK Isoforms by TGF-β1 in murine mesangial cells
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DOI：
10.1074/jbc.m208573200
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发表时间：
2002-12-06
影响因子：
4.8
通讯作者：
Choi, ME
中科院分区：
文献类型：
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作者：
Wang, L;Ma, R;Choi, ME
转化生长因子-β 1（TGF-β 1）是导致肾纤维化的细胞外基质（ECM）合成的强效诱导剂。参与这一过程的细胞内信号传导机制仍不完全清楚。丝裂原活化蛋白激酶（MAPK）是一种主要的应激信号转导途径，我们先前报道了TGF-β 1对大鼠系膜细胞p38 MAPK的激活及其在刺激pro-alpha 1（I）胶原中的作用。在这项研究中，我们进一步研究了TGF-β 1激活p38 MAPK的机制和MEK 3的作用，MEK 3是p38 MAPK的上游MAPK激酶，通过检测靶向破坏Mkk 3基因的效果。我们首先从MKK 3-null（Mkk 3-/-）和野生型（Mkk 3 +/+）对照小鼠中分离肾小球系膜细胞。在培养的野生型（Mkk 3 +/+）小鼠系膜细胞中，TGF-β 1处理诱导MKK 3和p38 MAPK在15分钟内快速磷酸化。相反，TGF-β 1不能诱导MKK 3缺陷（Mkk 3-/-）小鼠系膜细胞中MKK 3或p38 MAPK的磷酸化，表明TGF-β 1诱导的p38 MAPK激活需要MKK 3。TGF-β 1在野生型（Mkk 3 +/+）系膜细胞中选择性激活p38 MAPK亚型p38 α和p38 δ，但在MKK 3缺陷型（Mkk 3-/-）系膜细胞中不激活。因此，p38 a和p38 delta的激活依赖于TGF-β 1对上游MKK 3的激活。此外，MKK 3缺陷导致TGF-β 1刺激的pro-alpha 1（I）胶原蛋白表达上调的选择性破坏，但不是TGF-β 1诱导的纤连蛋白和派-1。这些数据表明，MKK是TGF-β 1信号通路的关键组分，其活化是随后的p38 a和p388 MAPK活化和TGF-β 1刺激胶原蛋白所必需的。
Transforming growth factor-beta1 (TGF-beta1) is a potent inducer of extracellular matrix (ECM) synthesis that leads to renal fibrosis. Intracellular signaling mechanisms involved in this process remain incompletely understood. Mitogen-activated protein kinase (MAPK) is a major stress signal-transducing pathway, and we have previously reported activation of p38 MAPK by TGF-beta1 in rat mesangial cells and its role in the stimulation of pro-alpha1 (I) collagen. In this study, we further investigated the mechanism of p38 MAPK activation by TGF-beta1 and the role of MEK3, an upstream MAPK kinase of p38 MAPK, by examining the effect of targeted disruption of the Mkk3 gene. We first isolated glomerular mesangial cells from MKK3-null (Mkk3-/-) and wild-type (Mkk3+/+) control mice. Treatment with TGF-beta1 induced rapid phosphorylation of MKK3 as well as p38 MAPK within 15 min in cultured wild-type (Mkk3+/+) mouse mesangial cells. In contrast, TGF-beta1 failed to induce phosphorylation of either MKK3 or p38 MAPK in MKK3-deficient (Mkk3-/-) mouse mesangial cells, indicating that MKK3 is required for TGF-beta1-induced p38 MAPK activation. TGF-beta1 selectively activated the p38 MAPK isoforms p38alpha and p38delta in wild-type (Mkk3+/+) mesangial cells, but not in MKK3-deficient (Mkk3-/-) mesangial cells. Thus, activation of p38a and p38delta is dependent on the activation of upstream MKK3 by TGF-beta1. Furthermore, MKK3 deficiency resulted in a selective disruption of TGF-beta1-stimulated up-regulation of pro-alpha1(I) collagen expression but not TGF-beta1 induction of fibronectin and PAI-1. These data demonstrate that the MKK is a critical component of the TGF-beta1 signaling pathway, and its activation is required for subsequent p38a and p388 MAPK activation and collagen stimulation by TGF-beta1.