A mitochondrial kinase complex is essential to mediate an ERK1/2-dependent phosphorylation of a key regulatory protein in steroid biosynthesis.
A mitochondrial kinase complex is essential to mediate an ERK1/2-dependent phosphorylation of a key regulatory protein in steroid biosynthesis.
复制标题
DOI：
10.1371/journal.pone.0001443
复制
发表时间：
2008-01-16
期刊：
影响因子：
3.7
通讯作者：
Podestá EJ
中科院分区：
文献类型：
--
作者：
Poderoso C;Converso DP;Maloberti P;Duarte A;Neuman I;Galli S;Cornejo Maciel F;Paz C;Carreras MC;Poderoso JJ;Podestá EJ
已知 ERK1/2 参与激素刺激的类固醇合成，但其确切作用和潜在机制仍然难以捉摸。 ERK1/2 磷酸化和类固醇生成均可能由 cAMP/cAMP 依赖性蛋白激酶 (PKA) 依赖性和非依赖性机制触发；然而，cAMP 激活 ERK1/2 会导致最大类固醇生成率，而表皮生长因子 (EGF) 激活则不会。我们通过蛋白质印迹分析和共聚焦研究证明，在 Leydig 转化的 MA-10 细胞系中，颞叶线粒体 ERK1/2 激活对于 PKA 介导的类固醇生成是必需的。 PKA 活性导致组成型线粒体 MEK1/2 池的磷酸化，对胞质 MEK 的影响较低，而 EGF 则主要促进胞质 MEK 激活和核 pERK1/2 定位。这些结果可以解释为什么 PKA 比 EGF 更有利于线粒体中 ERK1/2 的更持久激活。通过离体实验，我们发现线粒体最大类固醇生成是类固醇生成急性调节蛋白（StAR）（类固醇生物合成中的关键调节成分）、活性 ERK1/2 和 PKA 相互作用的结果。我们的结果表明线粒体 StAR 和 ERK1/2 之间存在相互作用，涉及具有类似于 ERK 底物的连续碱性疏水基序的 D 结构域。由于这种结合并且仅在胆固醇存在的情况下，ERK1/2 才会在 Ser232 位点磷酸化 StAR。将 Ser232 定向诱变为非磷酸化氨基酸（例如 Ala (StAR S232A)）可通过活性 ERK1/2 抑制体外 StAR 磷酸化。用 StAR S232A 瞬时转染 MA-10 细胞显着降低了孕酮产量。总之，我们在此证明 StAR 是 ERK1/2 的新型底物，并且线粒体 ERK1/2 是调节胆固醇转运的多聚蛋白激酶复合物的一部分。强调了 MAPK 在线粒体功能中的作用。
ERK1/2 is known to be involved in hormone-stimulated steroid synthesis, but its exact roles and the underlying mechanisms remain elusive. Both ERK1/2 phosphorylation and steroidogenesis may be triggered by cAMP/cAMP-dependent protein kinase (PKA)-dependent and-independent mechanisms; however, ERK1/2 activation by cAMP results in a maximal steroidogenic rate, whereas canonical activation by epidermal growth factor (EGF) does not. We demonstrate herein by Western blot analysis and confocal studies that temporal mitochondrial ERK1/2 activation is obligatory for PKA-mediated steroidogenesis in the Leydig-transformed MA-10 cell line. PKA activity leads to the phosphorylation of a constitutive mitochondrial MEK1/2 pool with a lower effect in cytosolic MEKs, while EGF allows predominant cytosolic MEK activation and nuclear pERK1/2 localization. These results would explain why PKA favors a more durable ERK1/2 activation in mitochondria than does EGF. By means of ex vivo experiments, we showed that mitochondrial maximal steroidogenesis occurred as a result of the mutual action of steroidogenic acute regulatory (StAR) protein –a key regulatory component in steroid biosynthesis-, active ERK1/2 and PKA. Our results indicate that there is an interaction between mitochondrial StAR and ERK1/2, involving a D domain with sequential basic-hydrophobic motifs similar to ERK substrates. As a result of this binding and only in the presence of cholesterol, ERK1/2 phosphorylates StAR at Ser232. Directed mutagenesis of Ser232 to a non-phosphorylable amino acid such as Ala (StAR S232A) inhibited in vitro StAR phosphorylation by active ERK1/2. Transient transfection of MA-10 cells with StAR S232A markedly reduced the yield of progesterone production. In summary, here we show that StAR is a novel substrate of ERK1/2, and that mitochondrial ERK1/2 is part of a multimeric protein kinase complex that regulates cholesterol transport. The role of MAPKs in mitochondrial function is underlined.
登录
查看更多内容
影响因子：
5.3
作者：
CHAREST, DL;MORDRET, G;PELECH, SL
通讯作者：
PELECH, SL
影响因子：
4.1
作者：
Bardwell, AJ;Abdollahi, M;Bardwell, L
通讯作者：
Bardwell, L
影响因子：
4.8
作者：
ASCOLI, M
通讯作者：
ASCOLI, M
影响因子：
20.1
作者：
Baines, CP;Zhang, J;Ping, P
通讯作者：
Ping, P
影响因子：
4.8
作者：
Fantz, DA;Jacobs, D;Kornfeld, K
通讯作者：
Kornfeld, K