Differential internalization of mammalian and non-mammalian gonadotropin-releasing hormone receptors - Uncoupling of dynamin-dependent internalization from mitogen-activated protein kinase signaling
Differential internalization of mammalian and non-mammalian gonadotropin-releasing hormone receptors - Uncoupling of dynamin-dependent internalization from mitogen-activated protein kinase signaling
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DOI：
10.1074/jbc.m104542200
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发表时间：
2001-10-26
影响因子：
4.8
通讯作者：
McArdle, CA
中科院分区：
文献类型：
--
作者：
Hislop, JN;Everest, HM;McArdle, CA
G蛋白偶联受体的脱敏和内化可以反映β-抑制蛋白的受体磷酸化依赖性结合，其防止G蛋白活化并靶向受体以通过网格蛋白包被的囊泡内化。这些可以被发动蛋白项圈夹断，控制受体内化的蛋白质也可以介导促分裂原活化蛋白激酶信号传导。促性腺激素释放激素（GnRH）通过网格蛋白包被的囊泡刺激其受体的内化。哺乳动物GnRH受体（GnRH-R）的独特之处在于它们缺乏C-末端尾，并且不会迅速脱敏，而非哺乳动物GnRH-R具有C-末端尾，并且在研究中，确实迅速脱敏和内化。使用重组腺病毒表达人类和非洲爪蟾GnRH-Rs，我们已经探讨了受体内化和丝裂原活化蛋白激酶信号转导在HeLa细胞与调控四环素控制表达的野生型或显性失活突变体（K44 A）的发动蛋白。这些受体是磷脂酶C偶联的，具有适当的配体亲和力和特异性。K44 A发动蛋白的表达没有改变人类GnRH-R的内化，但显着降低非洲爪蟾GnRH-R（和表皮生长因子（EGF）受体）的内化。阻断网格蛋白介导的内化（蔗糖）取消所有三种受体的内化。这两种GnRH-R也介导ERK 2的磷酸化，并且对于这两种受体，这被K44 A动力蛋白抑制。EGF和蛋白激酶C介导的ERK 2磷酸化也是如此。ERK 2磷酸化也被蛋白激酶C抑制剂抑制，但不受EGF受体酪氨酸激酶抑制剂的影响。我们的结论是：a）脱敏和非脱敏GnRH-R通过功能不同的机制靶向网格蛋白包被的囊泡介导的内化，B）GnRII-R向ERK 2的信号传导是动力蛋白依赖性的，c）这并不反映对动力蛋白依赖性GnRH-R内化的依赖性。
Desensitization and internalization of G-protein-coupled receptors can reflect receptor phosphorylation-dependent binding of beta -arrestin, which prevents G-protein activation and targets receptors for internalization via clathrin-coated vesicles. These can be pinched off by a dynamin collar, and proteins controlling receptor internalization can also mediate mitogen-activated protein kinase signaling. Gonadotropin-releasing hormone (GnRH) stimulates internalization of its receptors via clathrin-coated vesicles. Mammalian GnRH receptors (GnRH-Rs) are unique in that they lack C-terminal tails and do not rapidly desensitize, whereas non-mammalian GnRH-R have C-terminal tails and, where investigated, do rapidly desensitize and internalize. Using recombinant adenovirus expressing human and Xenopus GnRH-Rs we have explored the relationship between receptor internalization and mitogen-activated protein kinase signaling in HeLa cells with regulated tetracycline-controlled expression of wild-type or a dominant negative mutant (K44A) of dynamin. These receptors were phospholipase C-coupled and had appropriate ligand affinity and specificity. K44A dynamin expression did not alter human GnRH-R internalization but dramatically reduced internalization of Xenopus GnRH-R (and epidermal growth factor (EGF) receptor). Blockade of clathrin-mediated internalization (sucrose) abolished internalization of all three receptors. Both GnRH-Rs also mediated phosphorylation of ERK 2 and for both receptors, this was inhibited by K44A dynamin. The same was true for EGF- and protein kinase C-mediated ERK 2 phosphorylation. ERK 2 phosphorylation was also inhibited by a protein kinase C inhibitor but not affected by an EGF receptor tyrosine kinase inhibitor. We conclude that a) desensitizing and non-desensitizing GnRH-Rs are targeted for clathrin-coated vesicle-mediated internalization by functionally distinct mechanisms, b) GnRII-R signaling to ERK 2 is dynamin-dependent and c) this does not reflect a dependence on dynamin-dependent GnRH-R internalization.