Regulation of intracellular signaling cascades by GNRH pulse frequency in the rat pituitary: roles for CaMK II, ERK, and JNK activation.
Regulation of intracellular signaling cascades by GNRH pulse frequency in the rat pituitary: roles for CaMK II, ERK, and JNK activation.
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DOI：
10.1095/biolreprod.108.070987
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发表时间：
2008-11
影响因子：
3.6
通讯作者：
Marshall JC
中科院分区：
文献类型：
--
作者：
Burger LL;Haisenleder DJ;Aylor KW;Marshall JC
脉动性GnRH （GnRH）对LH和FSH亚基基因的调控存在差异，频率越快越有利于Lhb的转录，频率越慢越有利于Fshb的转录。多种细胞内通路介导GNRH的作用，包括CaMK II （CAMK2）、ERK和JNK。我们研究了这些途径的激活是否受体内GNRH脉冲频率的调节。GNRH缺陷大鼠接受GNRH脉冲（每30或240 min 25ng iv，持续8h，对照）。在最后一次脉冲后5分钟采集垂体，将其切开，一半提取RNA（用于测量β -亚基初级转录物[PT]），另一半提取蛋白质。磷酸化（磷酸化）CAMK2、ERK （MAPK1/3，分别称为p42 ERK2和p44 ERK1）和JNK （MAPK8/9，分别称为p46 JNK1和p54 JNK2）通过western blotting测定。30分钟脉冲对Lhb PT的最大刺激（8倍），而240分钟脉冲对Fshb PT的最佳刺激（3倍）。两种GNRH脉冲频率均使phospho-CAMK2增加4倍。30分钟和240分钟脉冲均可刺激MAPK1/3的激活，但较慢GNRH脉冲（240分钟= 4倍，30分钟= 2倍）对MAPK3的磷酸化显著增强。在这种模式下，脉动GNRH对MAPK8/9的激活没有影响，但先前的研究结果表明，GNRH诱导的MAPK8/9的激活是延迟的，GNRH后5分钟可能不是观察MAPK8/9激活的最佳时间。这些数据表明，CAMK2可被GNRH激活，但不以频率依赖的方式激活，而MAPK3则最大程度地受到慢频率GNRH脉冲的刺激。因此，ERK对慢脉冲频率的反应是介导Fhb对GNRH转录反应的机制的一部分。
Pulsatile GnRH (GNRH) differentially regulates LH and FSH subunit genes, with faster frequencies favoring Lhb transcription and slower favoring Fshb. Various intracellular pathways mediate the effects of GNRH, including CaMK II (CAMK2), ERK and JNK. We examined if activation of these pathways are regulated by GNRH pulse frequency in vivo. GNRH deficient rats received GNRH pulses (25ng iv every 30 or 240 min for 8h, vehicle to controls). Pituitaries were collected 5 min after the last pulse, bisected and one half processed for RNA (to measure beta-subunit primary transcripts [PT]) and the other for protein. Phosphorylated (phospho) CAMK2, ERK (MAPK1/3, also known as p42 ERK2 and p44 ERK1 respectively) and JNK (MAPK8/9, also known as p46 JNK1 and p54 JNK2 respectively) were determined by western blotting. 30 min pulses maximally stimulated Lhb PT (8-fold), whereas 240 min was optimal for Fshb PT (3-fold increase). Both GNRH pulse frequencies increased phospho-CAMK2 4-fold. Activation of MAPK1/3 was stimulated by both 30 and 240 min pulses, but phosphorylation of MAPK3 was significantly greater following slower GNRH pulses (240 min = 4-fold, 30 min = 2-fold). MAPK8/9 activation was unchanged by pulsatile GNRH in this paradigm, but as previous results showed that GNRH induced activation of MAPK8/9 is delayed, 5 min post GNRH may not be optimal to observe MAPK8/9 activation. These data show that CAMK2 is activated by GNRH but not in a frequency dependant manner, whereas MAPK3 is maximally stimulated by slow frequency GNRH pulses. Thus, the ERK response to slow pulse frequency is part of the mechanisms mediating Fhb transcriptional responses to GNRH.
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影响因子：
4.1
作者：
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通讯作者：
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DOI：
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