文昌鱼神经系统、哈氏窝和性腺GnRH受体mRNA原位杂交的研究

用地高辛标记的寡核苷酸探针对ＧｎＲＨ受体在文昌鱼（Ｂｒａｎｃｈｉｏｓｔｏｍａ ｂｅｌｃｈｅｒｉ）神经系统、哈氏窝和性腺中的定位和表达进行原位杂交研究。结果显示,神经系统中神经细胞、尤其是在中脑右侧延伸出与哈氏窝相接触的漏斗样结构中的神经细胞、哈氏窝上皮细胞以及雌雄性腺中生殖细胞都有ＧｎＲＨ受体ｍＲＮＡ杂交信号,信号物质分布于胞质,胞核为阴性。表明文昌鱼神经系统、哈氏窝和性腺都能合成ＧｎＲＨ受体,从     

神经内分泌因子调控鱼类生殖和生长的相互作用

脊椎动物的生长与生殖活动有着密切的联系并相互作用。许多调节生长和代谢活动的内分泌因子对青春期或者性腺的发育产生影响。同样,调节生殖活动的许多激素亦同时对生长和代谢产生影响。近年来,我们和其他学者对鱼类生长和生殖的神经内分泌调节的相互作用进行了研究,主要的进展是：①在促进性腺的激素影响生长方面,发现促性腺激素释放激素（ＧｎＲＨ）和多巴胺都能和脑垂体生长激素细胞的特异性受体结合而刺激生长激素释放,并能     

蛙类促性腺激素释放激素的研究

蛙类促性腺激素释放激素的研究李远友林浩然（中山大学生物系广州５１０２７５）关键词促性腺激素释放激素特性作用蛙促性腺激素释放激素（ＧｎＲＨ）是脊椎动物脑垂体促性激素（ＧｔＨ）合成和释放的主要调节者,在生殖功能神经激素调控中起关键作用。近年来,哺乳类和...     

孕酮受体介导哺乳动物雌性生殖活动的分子机理

孕酮作为一种甾体激素,在哺乳动物雌性生殖活动的调控中起着关键作用。孕酮的生理功能依赖于核孕酮受体介导的基因组效应和膜孕酮受体介导的非基因组效应,这两种效应共同介导了孕酮在各种雌性生殖活动中的不同作用,包括排卵、胚胎植入、妊娠维持、分娩启动和乳腺发育等。近年来,通过基因芯片技术筛选出大量的孕酮下游靶基因,但至今未能在这些基因的启动子区域上找到传统意义上的孕酮响应元件,故推测核孕酮受体调节下游靶基因转录活动的方式可能不同于传统的类固醇核受体。基于目前最新的研究成果,文章综述了在哺乳动物雌性生殖活动中,孕酮受体介导各种生理效应的分子机理。     

前列腺素E分子网络对哺乳动物生殖的调控

磷脂酶A2、环氧合酶以及前列腺素E合成酶是前列腺素E合成途径中顺序起作用的重要酶类,其中前列腺素E合成酶有两种不同的亚型,分别介导不同的前列腺素E合成反应。前列腺素E可与其受体特异性结合,并通过旁分泌和自分泌两种形式调节细胞反应,参与多种生理过程。近来研究发现,前列腺素E受体不仅存于质膜,而在核膜上也大量存在。前列腺素E核受体介导的信号转导途径与膜受体介导的信号途径不同,对于基因转录的调控机制也不同。本文综述并探讨了上述分子所组成的网络系统在哺乳动物生殖,尤其是雌性生殖过程中所发挥的重要作用。     

孕酮受体基因的研究进展

摘要: 孕酮作为一种甾体激素, 在各种雌性哺乳动物生殖活动中起关键作用。在人类和其他脊椎动物中, 孕酮的生物活性主要是通过两个孕酮受体PGR-A和PGR-B转录活性的调节来介导。文章介绍了孕酮受体基因的结构、表达调控和多态性, 并讨论了该基因与哺乳动物生殖功能的关系。     

淋巴细胞糖皮质激素受体与免疫的相互关系

糖上质激素受体介导信号是免疫细胞发育分化,克隆选择,生存与死亡平衡调节的主要机制之一,对免疫功能既有抑制作用又有促进作用,其免疫调节作用具有组织或细胞特异性和浓度依赖性。免疫功能异常影响ＧＲ表达,ＧＲ异常也引起免疫功能改变,ＧＲ结构或功能异常是某些疾病发生的直接或间接原因。     

M受体亚型与G蛋白

５种不同的Ｍ受体亚型的基因已被克隆，用免疫沉淀法观察了它们在体内的分布；Ｇ蛋白调节许多膜受体介导的细胞内功能，在牛的中枢神经系统中发现至少有５种独立的Ｇ蛋白，且每种Ｇ蛋白都由３个亚基构成。实验表明，５种Ｍ受体亚型通过不同的Ｇ蛋白，可同时与ｃＡＭＰ改变和ＰＩ翻转发生偶联作用。     

激素和人工诱导鱼类繁殖

鱼类在蓄养条件下,由于环境条件变化使脑垂体不能大量分泌产生促性腺激素（ＧｔＨ）因而通常不能自行产卵,必需进行人工催产,许多鱼类的ＧｔＨ分泌活动受神经内分泌双重调节,即促性腺激素释放激素刺激（ＧｎＲＨ）而多巴胺抑制ＧｔＨ的释放,因此,使用高少性的ＧｎＲＨ类似物和多巴胺拮抗物能十分有效地刺激养殖鱼类释放ＧｔＨ和诱导产卵。海水鱼类产卵习性和淡水鱼类不同,还需研制适合海水养殖鱼类生殖生理特性的催产术。     

几种神经内分泌因子对鲤促性腺激素释放激素（GnRH）释放的调节作 …

用离体静态培育系统进行的初步研究表明,在幼鲤,多巴胺（ＤＡ）显著刺激下丘脑片段和脑垂体碎片释放ＧｎＲＨ,并且是剂量依存的;促甲状腺素释放激素（ＴＲＨ）和γ－氨基酸丁酸（ＧＡＢＡ）对ＧｎＲＨ的释放没有影响。在成鲤,ＤＡ抑制下丘脑片希和脑垂体碎片释放ＧｎＲＨ,而ＴＲＨ和ＧＡＢＡ刺激ＧｎＲＨ的释放;ＤＡ对ＧＡＢＡ刺激的ＧｎＲＨ释放也具有抑制作用;ＴＲＨ和ＧＡＢＡ的协同作用对下丘脑和脑垂体ＧｎＲＨ释放活动     

Presence of immunoreactive gonadotropin releasing hormone (GnRH) and its receptor (GnRHR) in rat ovary during pregnancy

The present study aims at quantification of gonadotropin releasing hormone (GnRH) by radioimmunoassay, relative expression of its mRNA by real-time PCR accompanied by its cellular localization in the rat ovary by immunonohistochemistry (IHC) during different time points of pregnancy. To determine the involvement of endogenous ovarian GnRH in receptor mediated local autocrine/paracrine functions within the ovary, the cell specific localization of the classical receptor for GnRH (GnRHR) in the ovary by IHC and expression pattern of its mRNA were studied during pregnancy. Receptor expression during each time point within the ovary was reconfirmed by Western blot analysis accompanied by densitometric analysis of the signal intensity. Results reveal that the content of ovarian GnRH reaches its maximum on Day 20. The densitometric analysis of GnRHR receptor expression from Western blot study exhibits a decreasing trend by Day 20. Presence of GnRH and GnRHR mRNA in the ovary indicates the local synthesis of both ligand and receptor in the rat ovary. Differential expression of GnRH/GnRHR in the corpus luteum throughout pregnancy strengthens the hypothesis of the involvement of ovarian GnRH in local ovarian functions by receptor-mediated mechanisms. The expression of GnRH and GnRHR in the atretic antral follicles is indicative of the possible involvement of this decapeptide in processes like follicular atresia. The expression of GnRH/GnRHR in the nonatretic antral follicles and their oocytes requires further in-depth investigation. Collectively, this study for the first time reveals the presence of endogenous ovarian GnRH/GnRHR supporting their possible involvement in local autocrine/paracrine functions during pregnancy.     

Homologous regulation of the gonadotropin-releasing hormone receptor gene is partially mediated by protein kinase C activation of an activator protein-1 element

Homologous regulation of GnRH receptor (GnRHR) gene expression is an established mechanism for controlling the sensitivity of gonadotropes to GnRH. We have found that expression of the GnRHR gene in the gonadotrope-derived alpha T3-1 cell line is mediated by a tripartite enhancer that includes a consensus activator protein-1 (AP-1) element, a binding site for SF-1 (steroidogenic factor-1), and an element we have termed GRAS (GnRHR-activating sequence). Further, in transgenic mice, approximately 1900 b.p. of the murine GnRHR gene promoter are sufficient for tissue-specific expression and GnRH responsiveness. The present studies were designed to further delineate the molecular mechanisms underlying GnRH regulation of GnRHR gene expression. Vectors containing 600 bp of the murine GnRHR gene promoter linked to luciferase (LUC) were transiently transfected into alpha T3-1 cells and exposed to treatments for 4 or 6 h. A GnRH-induced, dose-dependent increase in LUC expression of the -600 promoter was observed with maximal induction of LUC noted at 100 nM GnRH. We next tested the ability of GnRH to stimulate expression of vectors containing mutations in each of the components of the tripartite enhancer. GnRH responsiveness was lost in vectors containing mutations in AP-1. Gel mobility shift data revealed binding of fos/jun family members to the AP-1 element of the murine GnRHR promoter. Treatment with GnRH or phorbol-12-myristate-13-acetate (PMA) (100 nM), but not forskolin (10 microM), increased LUC expression, which was blocked by the protein kinase C (PKC) inhibitor, GF109203X (100 nM), and PKC down-regulation (10 nM PMA for 20 h). In addition, a specific MEK1/MEK2 inhibitor, PD98059 (60 microM), reduced the GnRH and PMA responses whereas the L-type voltage-gated calcium channel agonist, +/- BayK 8644 (5 microM), and antagonist, nimodipine (250 nM), had no effect on GnRH responsiveness. Furthermore, treatment of alpha T3-1 cells with 100 nM GnRH stimulated phosphorylation of both p42 and p44 forms of extracellular signal-regulated kinase (ERK), which was completely blocked with 60 microM PD98059. We suggest that GnRH regulation of the GnRHR gene is partially mediated by an ERK-dependent activation of a canonical AP-1 site located in the proximal promoter of the GnRHR gene.     

Gonadotropin-releasing hormone: GnRH receptor signaling in extrapituitary tissues

Gonadotropin-releasing hormone (GnRH) has historically been known as a pituitary hormone; however, in the past few years, interest has been raised in locally produced, extrapituitary GnRH. GnRH receptor (GnRHR) was found to be expressed in normal human reproductive tissues (e.g. breast, endometrium, ovary, and prostate) and tumors derived from these tissues. Numerous studies have provided evidence for a role of GnRH in cell proliferation. More recently, we and others have reported a novel role for GnRH in other aspects of tumor progression, such as metastasis and angiogenesis. The multiple actions of GnRH could be linked to the divergence of signaling pathways that are activated by GnRHR. Recent observations also demonstrate cross-talk between GnRHR and growth factor receptors. Intriguingly, the classical G(alphaq)-11-phospholipase C signal transduction pathway, known to function in pituitary gonadotropes, is not involved in GnRH actions at nonpituitary targets. Herein, we review the key findings on the role of GnRH in the control of tumor growth, progression, and dissemination. The emerging role of GnRHR in actin cytoskeleton remodeling (small Rho GTPases), expression and/or activity of adhesion molecules (integrins), proteolytic enzymes (matrix metalloproteinases) and angiogenic factors is explored. The signal transduction mechanisms of GnRHR in mediating these activities is described. Finally, we discuss how a common GnRHR may mediate different, even opposite, responses to GnRH in the same tissue/cell type and whether an additional receptor(s) for GnRH exists.     

SET Protein Interacts with Intracellular Domains of the Gonadotropin-releasing Hormone Receptor and Differentially Regulates Receptor Signaling to cAMP and Calcium in Gonadotrope Cells

In mammals, the receptor of the neuropeptide gonadotropin-releasing hormone (GnRHR) is unique among the G protein-coupled receptor (GPCR) family because it lacks the carboxyl-terminal tail involved in GPCR desensitization. Therefore, mechanisms involved in the regulation of GnRHR signaling are currently poorly known. Here, using immunoprecipitation and GST pull-down experiments, we demonstrated that SET interacts with GnRHR and targets the first and third intracellular loops. We delineated, by site-directed mutagenesis, SET binding sites to the basic amino acids ⁶⁶KRKK⁶⁹ and ²⁴⁶RK²⁴⁷, located next to sequences required for receptor signaling. The impact of SET on GnRHR signaling was assessed by decreasing endogenous expression of SET with siRNA in gonadotrope cells. Using cAMP and calcium biosensors in gonadotrope living cells, we showed that SET knockdown specifically decreases GnRHR-mediated mobilization of intracellular cAMP, whereas it increases its intracellular calcium signaling. This suggests that SET influences signal transfer between GnRHR and G proteins to enhance GnRHR signaling to cAMP. Accordingly, complexing endogenous SET by introduction of the first intracellular loop of GnRHR in αT3-1 cells significantly reduced GnRHR activation of the cAMP pathway. Furthermore, decreasing SET expression prevented cAMP-mediated GnRH stimulation of Gnrhr promoter activity, highlighting a role of SET in gonadotropin-releasing hormone regulation of gene expression. In conclusion, we identified SET as the first direct interacting partner of mammalian GnRHR and showed that SET contributes to a switch of GnRHR signaling toward the cAMP pathway.     

大白鼠颌下腺促性腺激素释放激素受体(GnRHR)mRNA的RT-PCR和原位杂交的研究

本实验采用RT－PCR法探讨大白鼠颌下腺是否存在GnRH受体mRNA,并用原位杂交法对其细胞定位进行了研究。结果显示RT－PCR可扩增出大白鼠颌下腺GnRH受体mRNA的特异性片段,其碱基数与设计的一致,原位杂交发现颌下腺浆液性腺泡上皮细胞、颗粒曲管、排泄管及分泌管上皮细胞内有GnRH受体mRNA的杂交信号,信号物质分布于胸质内,胞核阴性。上述结果表明大白鼠颌下腺能合成GnRH受体,颌下腺产生的GnRH可作用于颌上腺的靶细胞,参与颌下腺生理功能的调节。