Identification of a Novel Functional Corticotropin-Releasing Hormone (CRH2) in Chickens and Its Roles in Stimulating Pituitary TSHβ Expression and ACTH Secretion
Identification of a Novel Functional Corticotropin-Releasing Hormone (CRH2) in Chickens and Its Roles in Stimulating Pituitary TSHβ Expression and ACTH Secretion
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鸡中新型功能性促肾上腺皮质激素释放激素 (CRH2) 的鉴定及其在刺激垂体 TSH β 表达和 ACTH 分泌中的作用
DOI：
10.3389/fendo.2019.00595
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发表时间：
2019-08-29
影响因子：
5.2
通讯作者：
Wang, Yajun
中科院分区：
文献类型：
--
作者：
Bu, Guixian;Fan, Jie;Wang, Yajun
促肾上腺皮质激素释放激素(CRH)与其结构和功能相关的神经肽一起构成CRH家族，在多种生理过程中发挥重要作用。最近，在脊椎动物中发现了该家族的一个新成员，即CRH2，然而，它的功能和生理作用仍然是一个悬而未决的问题。在本研究中，我们以鸡(c-)为动物模型，研究了CRH2的表达和功能，并探讨了其在垂体前叶中的作用。结果表明：(1)cCRH2基因编码40个氨基酸的成熟多肽，与cCRH的氨基酸序列同源性(63%)高于其他CRH家族多肽(23-38%)：(2)利用pGL3-Cre-荧光素酶报告系统，我们证明了cCRH2在CHO细胞中表达时激活cCRH受体2(CRHR2)的能力类似于cCRHR1的15倍，表明cCRH2具有生物活性，其作用主要由CRHR2介导；(3)实时定量聚合酶链式反应显示，cCRH2在鸡的下丘脑和垂体前叶等组织中广泛表达，其转录可能受外显子1附近启动子的调控，在培养的DF-1和HEK293细胞中显示出较强的启动子活性；(4)在培养的鸡垂体细胞中，cCRH2能有效地刺激TSHβ的表达，但诱导ACTH分泌的效力较低，表明垂体/下丘脑CRH2具有调节垂体功能的作用。总之，我们的数据提供了第一个证据，表明CRH2的作用类似于CRH，但不完全相同，例如它对脑下垂体的不同作用，这有助于阐明CRH2在脊椎动物中的作用。
Corticotropin-releasing hormone (CRH), together with its structurally and functionally related neuropeptides, constitute the CRH family and play critical roles in multiple physiological processes. Recently, a novel member of this family, namely CRH2, was identified in vertebrates, however, its functionality and physiological roles remain an open question. In this study, using chicken (c-) as the animal model, we characterized the expression and functionality of CRH2 and investigated its roles in anterior pituitary. Our results showed that (1) cCRH2 cDNA is predicted to encode a 40-aa mature peptide, which shares a higher amino acid sequence identity to cCRH (63%) than to other CRH family peptides (23-38%); (2) Using pGL3-CRE-luciferase reporter system, we demonstrated that cCRH2 is similar to 15 fold more potent in activating cCRH receptor 2 (CRHR2) than cCRHR1 when expressed in CHO cells, indicating that cCRH2 is bioactive and its action is mainly mediated by CRHR2; (3) Quantitative real-time PCR revealed that cCRH2 is widely expressed in chicken tissues including the hypothalamus and anterior pituitary, and its transcription is likely controlled by promoters near exon 1, which display strong promoter activity in cultured DF-1 and HEK293 cells; (4) In cultured chick pituitary cells, cCRH2 potently stimulates TSH beta expression and shows a lower potency in inducing ACTH secretion, indicating that pituitary/hypothalamic CRH2 can regulate pituitary functions. Collectively, our data provides the first piece of evidence to suggest that CRH2 play roles similar, but non-identical, to those of CRH, such as its differential actions on pituitary, and this helps to elucidate the roles of CRH2 in vertebrates.