Regulation of glycoprotein hormone free alpha-subunit secretion and intracellular alpha-subunit content in primary pituitary cells.
Regulation of glycoprotein hormone free alpha-subunit secretion and intracellular alpha-subunit content in primary pituitary cells.
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原代垂体细胞中糖蛋白激素游离α亚基分泌和细胞内α亚基含量的调节。
作者：
J. Holdstock;J. Burrin
研究了GnRH、TRH、cAMP类似物、蛋白激酶C（PKC）激活剂、钙离子载体和钙通道阻滞剂对垂体糖蛋白激素游离α亚基分泌和细胞内游离α亚基含量的影响和相互作用。用GnRH（100 nM）处理分散的大鼠垂体细胞后，α-亚单位的释放呈时间依赖性，24 h时增加4.5倍（P < 0.05）。TRH（10 nM）的影响较小。促性腺激素释放激素（GnRH）或促甲状腺激素释放激素（TRH）刺激后8 h，细胞内α亚基含量迅速下降（下降61%，P < 0.05），24 h后保持不变。cAMP类似物8-溴-cAMP增加了α-亚单位的晚期释放（在24小时增加4.5倍; P < 0.05），而不影响细胞内α-亚单位的水平。共同加入8-溴-cAMP与GnRH或TRH逮捕了显着下降，在细胞内的α-亚基看到与GnRH或TRH单独。这些结果表明，虽然cAMP是能够刺激α-亚基分泌和维持细胞内容物在面对GnRH和TRH刺激分泌，它不介导他们的α-亚基的影响。与GnRH类似，PKC激活剂12-O-十四烷酰基-佛波醇-13-乙酸酯（TPA）迅速刺激α-亚单位分泌（4 h时增加1.7倍; P < 0.05），并在24 h内逐渐降低细胞含量（减少73%; P < 0.01）。这种作用的相似性和缺乏TPA与GnRH或TRH的累加效应的证明意味着PKC作为GnRH和TRH作用于α亚基的介质的作用。使用维拉帕米（50 μ M）阻断L-型钙通道对24小时内的基础或GnRH刺激的α分泌没有影响。钙离子载体A23187（3 μ M）阻断GnRH对α亚基释放的刺激作用，单独抑制游离α亚基分泌（24 h减少28%; P < 0.05）。我们的研究结果表明，既不是cAMP也不是细胞外钙离子的流入介导的GnRH或TRH对游离α-亚基分泌的影响。因此，我们假设PKC参与了大鼠垂体细胞中GnRH和TRH对α亚基的作用，尽管需要在PKC缺失的细胞中进行进一步的研究来证实这一假设。
The effects and interactions of GnRH, TRH, a cAMP analog, a protein kinase-C (PKC) activator, a calcium ionophore, and a calcium channel blocker on pituitary glycoprotein hormone free alpha-subunit secretion and intracellular free alpha-subunit content were investigated. Treatment of dispersed rat pituitary cells with GnRH (100 nM) effected a time-dependent release of alpha-subunit, reaching a 4.5-fold increase (P < 0.05) at 24 h. Smaller effects were observed with TRH (10 nM). A rapid and progressive fall in intracellular alpha-subunit content was observed for 8 h after stimulation with GnRH (61% decrease; P < 0.05) or TRH (55% decrease; P < 0.05), which then remained constant at 24 h. The cAMP analogue 8-bromo-cAMP augmented a late release of alpha-subunit (4.5-fold increase at 24 h; P < 0.05) without affecting levels of alpha-subunit within the cells. Co-addition of 8-bromo-cAMP with GnRH or TRH arrested the marked fall in intracellular alpha-subunit seen with GnRH or TRH alone. These results suggest that although cAMP is capable of stimulating alpha-subunit secretion and maintaining cell content in the face of GnRH- and TRH-stimulated secretion, it does not mediate their effects on alpha-subunit. Like GnRH, the PKC activator 12-O-tetradecanoyl-phorbol-13-acetate (TPA) rapidly stimulated alpha-subunit secretion (1.7-fold increase at 4 h; P < 0.05) and progressively lowered cell content over 24h (73% decrease; P < 0.01). This similarity of action and the lack of demonstration of additive effects of TPA with GnRH or TRH imply a role for PKC as a mediator of GnRH and TRH action on alpha-subunit. Using verapamil (50 microM) to block L-type calcium channels had no effect on either basal or GnRH-stimulated alpha-secretion over 24 h. The calcium ionophore A23187 (3 microM) blocked the stimulatory effects of GnRH on alpha-subunit release and alone inhibited free alpha-subunit secretion (28% decrease at 24 h; P < 0.05). Our results suggest that neither cAMP nor an influx of extracellular calcium mediates the effects of GnRH or TRH on free alpha-subunit secretion. Accordingly, we postulate that PKC is involved in the actions of GnRH and TRH on alpha-subunit in rat pituitary cells, although further studies are required in PKC-depleted cells to confirm this hypothesis.
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促甲状腺激素释放激素诱导垂体细胞中胞质游离 Ca2 浓度的峰值和平台。
DOI：
--
发表时间：
1984
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
Albert,PR;TashjianJr,AH
通讯作者：
TashjianJr,AH
促性腺激素释放激素刺激的黄体生成激素释放与磷酸肌醇产生之间的关系：钙拮抗剂和蛋白激酶 C 激活剂的研究。
影响因子：
4.8
作者：
Huckle,WR;Conn,PM
通讯作者：
Conn,PM
克隆垂体促性腺激素中促性腺激素释放激素诱导的钙信号传导。
影响因子：
4.8
作者：
Merelli,F;Stojilković,SS;Iida,T;Krsmanovic,LZ;Zheng,L;Mellon,PL;Catt,KJ
通讯作者：
Catt,KJ
评估 G 蛋白和磷酸肌醇生成在促性腺激素释放激素作用中的作用。
影响因子：
9.3
作者：
Hawes,BE;Conn,PM
通讯作者：
Conn,PM
体外促性腺激素亚基信使 RNA 对连续促性腺激素释放激素与脉冲促性腺激素释放激素的不同反应。
DOI：
10.1210/mend-4-4-557
发表时间：
1990
期刊：
Molecular endocrinology (Baltimore, Md.)
影响因子：
--
作者：
Weiss,J;Jameson,JL;Burrin,JM;CrowleyJr,WF
通讯作者：
CrowleyJr,WF