Biological Role of a Novel Testis Insulin-Like Protein

描述(申请人提供)：胰岛素家族的蛋白质在影响新陈代谢、生长和生殖的多效性生理过程中发挥重要作用。利用分子生物学和计算生物学技术，我们的实验室最近发现了胰岛素家族中的一个新成员，我们将其命名为Insl6(胰岛素样蛋白6)。Ins1 6在睾丸生殖细胞中的表达最强。Insl6基因结构的进化保守性表明该蛋白具有重要的生物学作用。然而，目前对INSL6的生物学作用尚不清楚。我们的初步研究已经确定了一名男性不育患者，其INSL6基因发生了杂合突变。我们的研究表明，已发现的突变改变了Insl6蛋白在细胞内的运输。特殊目的1对这些观察结果进行了扩展，并测试了INSL6基因突变与人类特有表型相关的假设。通过分析临床病史、体格检查、精子分析和内分泌情况，将建立基因-表型相关性。特定目的2验证了这样的假设，即通过靶向破坏小鼠Insl6基因而产生的Insl6缺失表型将反映Insl6的生物学作用。将对Insl6基因缺失的小鼠进行表型特征的评估，包括存活率、性分化、生育力、睾丸宏观和微观结构、精子分析和内分泌特征。 胰岛素基因家族新成员的发现使得这一蛋白质家族的新功能得以阐明。例如，在小鼠体内靶向干扰胰岛素样肽3(INSL3)揭示了这种多肽在睾丸下降中的关键作用。此外，最近INSL3的同源受体(LGR8)的发现以及隐睾症作为LGR8缺失表型之一的阐明强调了这一领域取得的令人兴奋的进展。这项提案中概述的实验结果将促进我们对Insl6生物学作用的理解，并为人类生殖和不孕不育等疾病提供见解。

DESCRIPTION (provided by applicant): The proteins of the insulin family play essential roles in pleotropic physiological processes affecting metabolism, growth, and reproduction. Using the techniques of molecular and computational biology our laboratory recently identified a novel member of the insulin family we termed Insl6 (insulin-like protein 6). Expression of Insl6 is greatest in germ cells of the testis. Evolutionary conservation of the structure of the Insl6 gene suggests an essential biological role for this protein. However, at present the biological role of Insl6 is not known. Our preliminary studies have identified a subject with male infertility with a heterozygous mutation in the INSL6 gene. Our studies indicate that the identified mutation alters the intra-cellular trafficking of the Insl6 protein. Specific Aim 1 expands on these observations and tests the hypothesis that mutations in the INSL6 gene are associated with characteristic phenotypes in the human. The genotype-phenotype correlation will be established by analysis of clinical history, physical examination, sperm analysis, and endocrine profile. Specific Aim 2 tests the hypothesis that the Insl6 null phenotype, generated by targeted disruption of the murine Insl6 gene, will reflect the biological role of Insl6. The Insl6 null mice will be evaluated for phenotypic characteristics including viability, sexual differentiation, fertility, testicular macro- and microstructure, sperm analysis, and endocrine profile. The identification of new members of the insulin gene family has led to the elucidation of novel functions for this family of proteins. For example, targeted disruption of insulin-like peptide 3 (Insl3) in the mouse revealed a critical role for this peptide in testicular descent. Furthermore, the recent discovery of the cognate receptor (LGR8) for Insl3 and the elucidation of cryptorchidism as one of components of the LGR8 null phenotype underscore the exciting advances made in this field. The results from experiments outlined in this proposal will advance our understanding of the biological role of Insl6 and provide insights into human reproduction and disorders such as infertility.