MAPK Phosphatase-1 (MKP-1) Expression Is Up-Regulated by hCG/cAMP and Modulates Steroidogenesis in MA-10 Leydig Cells
MAPK Phosphatase-1 (MKP-1) Expression Is Up-Regulated by hCG/cAMP and Modulates Steroidogenesis in MA-10 Leydig Cells
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DOI：
10.1210/en.2011-0021
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发表时间：
2011-07-01
期刊：
影响因子：
4.8
通讯作者：
Paz, Cristina
中科院分区：
文献类型：
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作者：
Brion, Laura;Maloberti, Paula M.;Paz, Cristina
MAP激酶（MAPKs），如ERK 1/2，在多种生理过程中发挥深远的影响。在类固醇激素合成细胞中，ERK 1/2参与类固醇激素合成急性调节蛋白的表达和激活，该蛋白在类固醇激素合成的调节中起核心作用。在MA-10 Leydig细胞中，LH和绒毛膜促性腺激素（CG）通过蛋白激酶A触发短暂的ERK 1/2激活，尽管导致ERK 1/2失活的事件尚未完全描述。在这里，我们描述的激素调节MAPK磷酸酶-1（MKP-1），一种酶，失活MAPKs，在MA-10细胞。在我们的实验中，人CG（hCG）/cAMP刺激通过转录作用迅速和短暂地增加MKP-1 mRNA水平。这种效应伴随着核和线粒体区室中蛋白质水平的增加。在瞬时表达flag-MKP-1蛋白的细胞中，hCG/cAMP以时间依赖性方式促进重组蛋白的蓄积（1 h时为10倍）。此外，hCG/cAMP触发ERK 1/2依赖性MKP-1磷酸化。阻断cAMP诱导的MAPK激酶/ERK活化可减少MKP-1磷酸化，但仅部分减少flag-MKP-1蛋白的积累。总之，这些结果表明，hCG在转录和翻译后水平调节MKP-1，蛋白磷酸化是参与这种调节的机制之一。我们的研究还表明，MKP-1过表达降低cAMP对ERK 1/2磷酸化，类固醇生成急性调节基因启动子活性，mRNA水平和类固醇生成的影响，而MKP-1下调小干扰RNA产生相反的效果。总之，我们的数据表明，hCG调节MKP-1的表达在多个阶段作为一个负反馈调节机制，以调节激素对ERK 1/2活性和类固醇生成的作用。（内分泌学152：2665-2677，2011）
MAP kinases (MAPKs), such as ERK1/2, exert profound effects on a variety of physiological processes. In steroidogenic cells, ERK1/2 are involved in the expression and activation of steroidogenic acute regulatory protein, which plays a central role in the regulation of steroidogenesis. In MA-10 Leydig cells, LH and chorionic gonadotropin (CG) trigger transient ERK1/2 activation via protein kinase A, although the events that lead to ERK1/2 inactivation are not fully described. Here, we describe the hormonal regulation of MAPK phosphatase-1 (MKP-1), an enzyme that inactivates MAPKs, in MA-10 cells. In our experiments, human CG(hCG)/cAMP stimulation rapidly and transiently increased MKP-1 mRNA levels by a transcriptional action. This effect was accompanied by an increase in protein levels in both nuclear and mitochondrial compartments. In cells transiently expressing flag-MKP-1 protein, hCG/cAMP promoted the accumulation of the recombinant protein in a time-dependent manner (10-fold at 1 h). Moreover, hCG/cAMP triggered ERK1/2-dependent MKP-1 phosphorylation. The blockade of cAMP-induced MAPK kinase/ERK activation abated MKP-1 phosphorylation but only partially reduced flag-MKP-1 protein accumulation. Together, these results suggest that hCG regulates MKP-1 at transcriptional and posttranslational level, protein phosphorylation being one of the mechanisms involved in this regulation. Our study also demonstrates that MKP-1 overexpression reduces the effects of cAMP on ERK1/2 phosphorylation, steroidogenic acute regulatory gene promoter activity, mRNA levels, and steroidogenesis, whereas MKP-1 down-regulation by small interfering RNA produces opposite effects. In summary, our data demonstrate that hCG regulates MKP-1 expression at multiple stages as a negative feedback regulatory mechanism to modulate the hormonal action on ERK1/2 activity and steroidogenesis. (Endocrinology 152: 2665-2677, 2011)