p38MAPK acts in the BMP7-dependent stimulatory pathway during epithelial cell morphogenesis and is regulated by Smad1
p38MAPK acts in the BMP7-dependent stimulatory pathway during epithelial cell morphogenesis and is regulated by Smad1
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DOI：
10.1074/jbc.m310526200
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发表时间：
2004-03-26
影响因子：
4.8
通讯作者：
Rosenblum, ND
中科院分区：
文献类型：
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作者：
Hu, MC;Wasserman, D;Rosenblum, ND
骨形态发生蛋白(BMP)-7在肾脏分支形态发生过程中发挥剂量依赖性的刺激和抑制作用。此前，我们发现激活素样激酶受体和Smad1在BMP依赖的抑制中起抑制作用(Piscione，T.D.，Phan，T.，and Rosenblum，N.D.(2001)AmJ.Physiol.280、F19-F33)。在这里，我们展示了p38丝裂原激活激酶(p38(MAPK))在BMP7依赖的刺激信号中的新作用。刺激剂量(0.25 nM)的BMP7以p38(MAPK)依赖的方式增加小鼠内髓集合管(mIMCD-3)细胞的p38(MAPK)活性，并刺激内源性激活转录因子2(ATF2)的磷酸化。相反，高剂量(10 NM)的BMP7抑制p38(MAPK)活性和内源性ATF2的磷酸化。BMP7处理对内源性SAPK/JNK或p44和p42(ERK1和ERK2)蛋白激酶的磷酸化水平没有显著影响。为了研究p38(MAPK)信号的功能重要性，我们在三维培养模型中发现，p38(MAPK)抑制剂SB203580可以阻断BMP7对mIMCD-3细胞形态发生的刺激作用，但对BMP7依赖的抑制作用没有影响。为了确定BMP7依赖的抑制信号抑制p38(MAPK)活性的机制，我们测量了配体非依赖的增强和抑制Smad信号的mIMCD-3模型中的p38(MAPK)活性。P38(MAPK)的基本活性在mIMCD-3细胞和表达活性激活素样激酶受体的胚胎肾组织中降低，但在稳定表达Smad1的显性阴性形式的mIMCD-3细胞中增加。我们得出结论：BMP7通过p38(MAPK)刺激肾上皮细胞形态发生，p38(MAPK)活性受Smad1负调控。
Bone morphogenetic protein (BMP)-7 exerts dose-dependent stimulatory and inhibitory effects during renal branching morphogenesis. Previously, we identified an inhibitory role for activin-like kinase receptors and Smad1 in BMP-dependent inhibition (Piscione, T. D., Phan, T., and Rosenblum, N. D. (2001) Am. J. Physiol. 280, F19-F33). Here we demonstrate a novel role for p38 mitogen-activated kinase (p38(MAPK)) in BMP7-dependent stimulatory signaling. Stimulatory doses (0.25 nM) of BMP7 increased p38(MAPK) activity and stimulated phosphorylation of endogenous activating transcription factor 2 (ATF2) in a p38(MAPK)-dependent manner in murine inner medullary collecting duct (mIMCD-3) cells. In contrast, high doses ( 10 nM) of BMP7 inhibited p38(MAPK) activity and phosphorylation of endogenous ATF2. Treatment with BMP7 exerted no significant effect on the levels of the phosphorylated forms of endogenous SAPK/JNK or p44 and p42 (ERK1 and ERK2) protein kinases. To investigate the functional importance of p38(MAPK) signaling, we showed that SB203580, a p38(MAPK) inhibitor, blocked the stimulatory effect of BMP7 on mIMCD-3 cell morphogenesis but had no effect on BMP7-dependent inhibition in a three-dimensional culture model. To identify mechanisms by which BMP7-dependent inhibitory signaling suppresses p38(MAPK) activity, we measured p38(MAPK) activity in ligand independent mIMCD-3 models of enhanced and suppressed Smad signaling. Basal activity of p38(MAPK) was decreased in mIMCD-3 cells and in embryonic kidney tissue expressing a constitutively active activin-like kinase receptor, but was increased in mIMCD-3 cells stably expressing a dominant negative form of Smad1. We conclude that BMP7 stimulates renal epithelial cell morphogenesis via p38(MAPK) and that p38(MAPK) activity is negatively regulated by Smad1.