Gonadotropin-releasing hormone activates the equine luteinizing hormone beta promoter through a protein kinase C/mitogen-activated protein kinase pathway.
Gonadotropin-releasing hormone activates the equine luteinizing hormone beta promoter through a protein kinase C/mitogen-activated protein kinase pathway.
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促性腺激素释放激素通过蛋白激酶 C/丝裂原激活蛋白激酶途径激活马黄体生成素 β 启动子。
DOI：
10.1095/biolreprod61.3.715
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发表时间：
1999
影响因子：
3.6
通讯作者：
Wolfe,MW
中科院分区：
文献类型：
--
作者：
Call,GB;Wolfe,MW
GnRH对LH分泌的调节已被充分理解，并涉及Ca2+动员。然而，GnRH激活LH β基因转录的机制存在争议。已知GnRH可升高细胞内钙并激活蛋白激酶C（PKC）通路。本研究评价了GnRH诱导LH β转录的途径。我们以前曾报道马LH β（eLH β − 448/+60）启动子在α T3 - 1细胞中有活性。因此，我们建立了一个克隆的、稳定转染的α T3 - 1促性腺激素细胞系，该细胞系含有与荧光素酶报告基因融合的eLH β启动子（− 448/+60）。给予GnRH激动剂导致启动子活性的诱导，该活性被拮抗剂antide完全抑制。各种影响钙的药物对启动子无影响。佛波醇12-肉豆蔻酸酯13-乙酸酯（PMA）的管理引起类似的激活，虽然低于，与GnRH。PKC的下调或药理学抑制完全阻断PMA对启动子的诱导，而GnRH的诱导仅部分减弱。用丝裂原活化蛋白激酶（MAPK）激酶抑制剂PD98059处理，可完全抑制PMA对eLH β的激活，但仅部分减弱GnRH的诱导。转录因子早期生长反应蛋白1（Egr 1）的表达与MAPK的激活完全相关，表明Egr 1是PKC/MAPK发挥作用的因子。我们的数据表明，GnRH通过激活涉及PKC-MAPK-Egr 1的信号转导级联来诱导eLH β启动子的活性，但对钙没有显著的需求。
GnRH regulation of LH secretion is well understood and involves Ca2+mobilization. However, the mechanism by which GnRH activates transcription of the LHβ gene is controversial. GnRH is known to elevate intracellular calcium and activate the protein kinase C (PKC) pathway. The present study evaluated the pathway(s) involved in GnRH induction of LHβ transcription. We have previously reported that the equine LHβ (eLHβ −448/+60) promoter is active in αT3-1 cells. Therefore, we created a clonal, stably transfected αT3-1 gonadotroph cell line harboring the eLHβ promoter (−448/+60) fused to the luciferase reporter gene. Administration of a GnRH agonist resulted in induction of promoter activity that was completely inhibited by the antagonist antide. Various calcium-affecting drugs had no effect on the promoter. Administration of phorbol 12-myristate 13-acetate (PMA) elicited an activation similar to, albeit lower than, that with GnRH. Down-regulation or pharmacological inhibition of PKC completely blocked PMA's induction of the promoter, while GnRH induction was only partly attenuated. Treatment with the mitogen-activated protein kinase (MAPK) kinase inhibitor, PD98059, completely inhibited the activation of eLHβ by PMA but only partly diminished GnRH's induction. Expression of the transcription factor, early growth response protein 1 (Egr1), correlated completely with activation of MAPK, suggesting that Egr1 is the factor through which PKC/MAPK acts. Our data suggest that GnRH induces activity of the eLHβ promoter by activating a signal transduction cascade involving PKC-MAPK-Egr1 but that has no significant requirement for calcium.