Physiology of LGR7 and LGR8 in Gonadal Tissues

描述（由申请人提供）：经典的激素松弛素属于具有保守的双链结构的肽激素家族。大量研究表明松弛素在妊娠和非妊娠状态下的女性生理中起重要作用，并且旁系同源基因INSL 3在男性生殖发育中起重要作用。尽管松弛素由卵巢黄体细胞产生，而INSL 3由睾丸Leydig细胞以及卵巢cal和黄体细胞产生，但它们在性腺中的生理作用尚不清楚。早期的研究表明松弛素和INSL 3结合位点存在于包括性腺在内的靶组织中。然而，这些配体的假定受体的研究是有限的，由于在进行这些蛋白质的配体结合试验在低水平表达的困难。我们最近的研究表明，松弛素激活孤儿受体LGR 7和LGR 8，而INSL 3特异性激活LGR 8。除了证明cAMP途径在LGR 7和LGR 8信号传导中的作用之外，我们产生了LGR 7的可溶性配体结合胞外域以用作功能性拮抗剂。用LGR 7的可溶性胞外域处理可延迟妊娠小鼠的分娩。在这里，我们建议通过测试嵌合受体的配体信号传导来分析对受体功能重要的LGR 7和LGR 8的结构域。基于我们在隐睾患者中LGR 8变体的发现，我们将进一步测试LGR 8变体的INSL 3激活。我们已经获得了初步的数据表明LGR 7和LGR 8在睾丸和卵巢中的表达，并建议阐明LGR 7和LGR 8在性腺生理中的生理作用。我们将描述LGR 7和LGR 8在特定性腺细胞类型中的表达及其对松弛素和INSL 3的反应，基于cAMP产生和其他反应。我们将使用LGR 7和LGR 8的可溶性胞外域作为功能性拮抗剂来证明松弛素和INSL 3在体内睾丸和卵巢生理学中的生理作用。拟议的研究应该提供一个更好的了解松弛素相关激素和LGR 7和LGR 8受体在性腺生理和其他生殖过程中的作用。

DESCRIPTION (provided by applicant): The classic hormone relaxin belongs to a family of peptide hormones with a conserved two-chain structure. Extensive studies have demonstrated that relaxin plays important roles in female physiology during pregnant and nonpregnant states and a paralogous gene, INSL3, is important in male reproductive development. Although relaxin is produced by ovarian luteal cells whereas INSL3 is produced by testis Leydig cells as well as ovarian the cal and luteal cells, their physiological roles in the gonads are unclear. Earlier studies suggested the presence of relaxin and INSL3 binding sites in target tissues including the gonads. However, studies on the putative receptors for these ligands were limited due to difficulties involved in performing ligand-binding assays for these proteins expressed at low levels. Our recent studies demonstrated that relaxin activates the orphan receptors LGR7 and LGR8 whereas INSL3 specifically activates LGR8. In addition to demonstrating the role of cAMP pathways in LGR7 and LGR8 signaling, we generated the soluble ligand-binding ectodomain of LGR7 to serve as a functional antagonist. Treatment with the soluble ectodomain of LGR7 delayed parturition of pregnant mice. Here, we propose to analyze the domains of LGR7 and LGR8 that are important for receptor function by testing ligand signaling of chimeric receptors. Based on our findings of LGR8 variants in cryptorchid patients, we will further test INSL3 activation of a LGR8 variant. We have obtained preliminary data indicating the expression of LGR7 and LGR8 in the testis and ovary and propose to elucidate the physiological roles of LGR7 and LGR8 in gonadal physiology. We will characterize the expression of LGR7 and LGR8 in specific gonadal cell types and their responsiveness to relaxin and INSL3 based on cAMP production and other responses. We will use the soluble ectodomains of LGR7 and LGR8 as functional antagonists to demonstrate the physiological roles of relaxin and INSL3 in testis and ovarian physiology in vivo. The proposed studies should provide a better understanding on the role of relaxin-related hormones and LGR7 and LGR8 receptors in gonadal physiology and other reproductive processes.