Pulsatile gonadotropin-releasing hormone stimulation of gonadotropin subunit transcription in rat pituitaries: Evidence for the involvement of Jun N-terminal kinase but not p38
Pulsatile gonadotropin-releasing hormone stimulation of gonadotropin subunit transcription in rat pituitaries: Evidence for the involvement of Jun N-terminal kinase but not p38
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DOI：
10.1210/en.2007-1113
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发表时间：
2008-01-01
期刊：
影响因子：
4.8
通讯作者：
Marshall, J. C.
中科院分区：
文献类型：
--
作者：
Haisenleder, D. J.;Burger, L. L.;Marshall, J. C.
我们研究了Jun n -末端激酶（JNK）和p38是否介导了正常大鼠垂体促性腺激素亚基对脉动性GnRH的转录反应。雌性大鼠体内给予单脉冲GnRH或载体，收集垂体，并测量磷酸化的JNK和p38。GnRH在5分钟内刺激JNK磷酸化增加，在GnRH后15分钟达到峰值（3倍）。刺激后15分钟，GnRH也使p38磷酸化增加2.3倍。给予大鼠垂体细胞60分钟脉冲GnRH或培养基加JNK抑制剂SP600125 （SP, 20 μ M）、p38抑制剂SB203580 （20 μ M）或载体。在载体处理组中，GnRH脉冲使LH β和FSH β初级转录物（PT）水平增加了3倍。SP抑制基础和GnRH诱导的FSH β PT升高一半，但对GnRH的反应幅度不变。相比之下，SP对基础LH β PT没有影响，但抑制了对GnRH的刺激反应。SB203580对GnRH对LH或FSH β PTs的作用没有影响。用MAPK激酶(MKK)-4和/或MKK-7的显性/阴性表达载体加大鼠LH β启动子荧光素酶构建物转染L β - t2细胞。GnRH刺激LH β启动子活性增加50倍，MKK-4和-7的显性/阴性组合抑制了80%的反应。因此，JNK（而不是p38）以不同的方式调节LH β和FSH β的转录。对于LH β， JNK在介导对脉动GnRH的反应中是必不可少的。JNK也调节FSH β转录（即维持基础表达），但在对GnRH的反应中不起作用。
We investigated whether Jun N-terminal kinase (JNK) and p38 mediate gonadotropin subunit transcriptional responses to pulsatile GnRH in normal rat pituitaries. A single pulse of GnRH or vehicle was given to female rats in vivo, pituitaries collected, and phosphorylated JNK and p38 measured. GnRH stimulated an increase in JNK phosphorylation within 5 min, which peaked 15 min after GnRH (3-fold). GnRH also increased p38 phosphorylation 2.3-fold 15 min after stimulus. Rat pituitary cells were given 60-min pulses of GnRH or media plus the JNK inhibitor SP600125 (SP, 20 mu M), p38 inhibitor SB203580 (20 mu M), or vehicle. In vehicle-treated groups, GnRH pulses increased LH beta and FSH beta primary transcript (PT) levels 3-fold. SP suppressed both basal and GnRH-induced increases in FSH beta PT by half, but the magnitude of responses to GnRH was unchanged. In contrast, SP had no effect on basal LH beta PT but suppressed the stimulatory response to GnRH. SB203580 had no effect on the actions of GnRH on either LH or FSH beta PTs. L beta-T2 cells were transfected with dominant/ negative expression vectors for MAPK kinase (MKK)-4 and/or MKK-7 plus a rat LH beta promoter-luciferase construct. GnRH stimulated a 50-fold increase in LH beta promoter activity, and the combination of MKK-4 and -7 dominant/ negatives suppressed the response by 80%. Thus, JNK (but not p38) regulates both LH beta and FSH beta transcription in a differential manner. For LH beta, JNK is essential in mediating responses to pulsatile GnRH. JNK also regulates FSH beta transcription (i.e. maintaining basal expression) but does not play a role in responses to GnRH.