Involvement of cAMP-response element binding protein in corticotropin-releasing factor (CRF)-induced down-regulation of CRF receptor 1 gene expression in rat anterior pituitary cells
Involvement of cAMP-response element binding protein in corticotropin-releasing factor (CRF)-induced down-regulation of CRF receptor 1 gene expression in rat anterior pituitary cells
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DOI：
10.1046/j.1365-2826.2002.00816.x
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发表时间：
2002-07-01
影响因子：
3.2
通讯作者：
Suda, T
中科院分区：
文献类型：
--
作者：
Kasagi, Y;Horiba, N;Suda, T
促肾上腺皮质激素释放因子(CRF)是一种主要的促肾上腺皮质激素从垂体前叶分泌，是下丘脑-垂体-肾轴的关键激活剂。我们先前报道CRF下调培养的大鼠垂体前叶细胞CRF-1受体(CRF-R1)mRNA的表达。本研究旨在阐明CRF诱导垂体前叶CRF-R1基因表达下调的信号转导系统。Northern印迹分析显示，在无血清条件下，10 nM CRF可降低培养的大鼠垂体前叶细胞CRF-R1mRNA水平。5 mM 8-Br-cAMP作用2 h后，CRF-R1mRNA水平下降，2 h后下降至基础水平的37+/-3%，处理后16 h仍维持在较低水平。蛋白激酶A(PKA)抑制剂(1um H-89)可完全抑制CRF诱导的CRF-R1mRNA表达下调。进一步检测发现，经10 MU的环磷酸腺苷反应元件结合蛋白(CREB)反义寡核苷酸处理后，CRF对CRF-R1mRNA的抑制作用在给药后2 h部分降至对照水平的79+/-4%。这些结果表明，CRF可能通过cAMP-PKA介导的机制下调大鼠垂体前叶细胞CRF-R1mRNA的表达，CREB可能至少介导了这种抑制作用的一部分。
Corticotropin-releasing factor (CRF) is a major secretagogue of adrenocorticotopic hormone from the anterior pituitary and a key activator of the hypothalamic-pituitary-ad renal axis. We previously reported that CRF down-regulates expression of the CRF type-1 receptor (CRF-R1) mRNA in cultured rat anterior pituitary cells. The present study was conducted to clarify the signal transduction systems involved in CRF-induced down-regulation of CRF-R1 gene expression in the anterior pituitary. Northern blot analysis revealed that, under serum-free conditions, 10 nM CRF decreased CRF-R1 mRNA levels in cultured rat anterior pituitary cells as we reported previously. Treatment with 5 mM 8-Br-cAMP reduced CRF-R1 mRNA levels within 2 h. The mRNA level fell to 37 +/- 3% of the basal level at 2 h and remained low for 16 h after treatment. This CRF-induced reduction of CRF-R1 mRNA expression was inhibited completely by pretreatment with protein kinase A (PKA) inhibitor (1 muM H-89). Further examination revealed that after pretreatment with 10 muM of antisense oligodeoxynucleotide for cyclic AMP-response element binding protein (CREB), the CRF-induced inhibition of CRF-R1 mRNA was partially decreased to 79 +/- 4% of the control level 2 h after administration of CRF. These findings indicate that CRF may down-regulate CRF-R1 mRNA expression via a cAMP-PKA-mediated mechanism in rat anterior pituitary cells, and that CREB may mediate at least a portion of this inhibitory effect.