Annexin 1-dependent actions of glucocorticoids in the anterior pituitary gland: Roles of the N-terminal domain and protein kinase C
Annexin 1-dependent actions of glucocorticoids in the anterior pituitary gland: Roles of the N-terminal domain and protein kinase C
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DOI：
10.1210/en.143.8.3060
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发表时间：
2002-08-01
期刊：
影响因子：
4.8
通讯作者：
Buckingham, J
中科院分区：
文献类型：
--
作者：
John, C;Cover, P;Buckingham, J
膜联蛋白1(ANXA1)是神经内分泌系统中糖皮质激素作用的重要介质。由于该蛋白在其他系统中的活性是通过其N-末端结构域的磷酸化来调节的，因此我们使用已建立的体外制剂，探讨了该结构域及其磷酸化状态对脑垂体内ANXA1活动的意义。两个N-端肽ANXA1(Ac2-26)和ANXA1(AC1-50)可抑制Forsklin诱导的ACTH和催乳素的释放，但它们缺乏亲本分子(ANYA1(1-346))的效力和完全效力，而其他较短的N-末端序列则没有作用。由ANXA1(1-44)和ANXA5的C-末端核心(ANXA5(20-320))组成的嵌合蛋白也能部分抑制多肽的释放。蛋白激酶C(PKC)拮抗剂(PKC19-36)可阻断地塞米松对Forsklin诱导肽释放的抑制作用，并减弱ANXA1(Ac2-26)的抗分泌作用。在其他系统中隔离PKC的ANXA5也产生了类似的效果。PKC19-36还阻断了地塞米松诱导的一种丝氨酸磷酸化的ANXA1从细胞质到细胞外表面的移位。这些结果表明：1)N-末端结构域在影响ANXA1抑制脑垂体肽释放中起重要作用；2)PKC依赖的机制对ANXA1的细胞输出和生物活性都是必不可少的；3)细胞输出的ANXA1是丝氨酸磷酸化的。
Annexin 1 (ANXA1) is an important mediator of glucocorticoid action in the neuroendocrine system. As the activity of this protein in other systems is modulated by phosphorylation of its N-terminal domain, we have explored the significance of this domain and its phosphorylation status to ANXA1 actions within the pituitary gland, using an established in vitro preparation. Two N-terminal peptides, ANXA1(Ac2-26), and ANXA1(Ac1-50), inhibited forskolin-evoked ACTH and prolactin release; however, they lacked the potency and full efficacy of the parent molecule (ANYA1(1-346)) whereas other shorter N-terminal sequences were without effect. A chimeric protein comprising ANXA1(1-44) and the C-terminal core of ANXA5 (ANXA5(20-320)) also produced a partial inhibition of peptide release. Protein kinase C (PKC) blockade (PKC19-36) abolished the inhibitory effects of dexamethasone on forskolin-evoked peptide release and attenuated the antisecretory actions Of ANXA1(Ac2-26). ANXA5, which sequesters PKC in other systems, produced similar effects. PKC19-36 also blocked the dexamethasone-induced translocation of a serine phosphorylated species of ANXA1 from the cytoplasm to the outer cell surface. These results suggest that 1) the N-terminal domain plays a fundamental role in effecting the inhibitory actions of ANXA1 on pituitary peptide release; 2) PKC-dependent mechanisms are essential for both the cellular exportation and the biological activity of ANXA1; and 3) ANXA1 exported from the cells is serine phosphorylated.