The role of transcription factor S-SOX5 in male fertility and sperm flagella formation

活动纤毛存在于脑室、气管、输卵管和精子鞭毛的上皮细胞中。他们玩 在体内的重要作用，包括维持脑脊液（CSF）循环，清除颗粒， 呼吸道的病原体和精子活力。运动纤毛的缺陷会导致多种疾病， 运动纤毛多为"9 + 2"轴丝。共享 不同组织中运动纤毛的结构表明存在共同的调节机制来控制 纤毛/鞭毛组分的表达。我们假设纤毛运动所必需的基因的表达 结构/功能由类似的机制调节，使得蛋白质组装成运动纤毛 以协调和及时的方式。精子鞭毛是一种特殊的运动纤毛。除了核心轴丝外， 辅助结构也在精子发生、精子细胞分化过程中组装。 在这个阶段，精子鞭毛组装所必需的一些基因被上调。但 对这组基因的转录调控知之甚少。通过分析假定的转录因子 精子鞭毛结构/功能所必需的基因的启动子区域中的结合位点， 鉴定了SOX 5作为纤毛/鞭毛基因的推定关键控制子。Sox-5是一个基因家族的成员， 显示与睾丸决定基因SRY的高运动性组（HMG）盒区域的同源性。鼠标 Sox 5基因编码两种主要的转录本：较长的Sox 5同种型，最初命名为L-Sox 5，但大多数作者 将其称为Sox 5;以及更短的同种型S-Sox 5。S-Sox 5转录本的第一个外显子是非翻译的。 外显子;并且其不存在于L-Sox 5转录物中。翻译的48 kDa S-SOX 5蛋白缺乏N-末端 84 kDa L-SOX 5蛋白的一半。两种SOX 5蛋白具有不同的组织分布。L-SOX 5是 在多种组织中表达，包括软骨、心脏、脑、肾、肺和骨骼肌，但在 在胚胎发育和细胞命运的调控过程中起着重要的作用 保持战略定力S-SOX 5蛋白仅在具有运动纤毛的组织中表达，包括脑、肺和肺。 尤其是睾丸。在精巢中，它位于减数分裂后圆形精子细胞的细胞核中。已经 显示S-SOX 5调节在睾丸中高度表达的几个基因的表达。我们假设 S-SOX 5调节一系列对精子鞭毛形成和功能至关重要的基因的表达。 为了验证这一假设，我们提出了以下具体目标：1。为了确定S-SOX 5在以下方面的关键作用： 鞭毛发生和雄性育性;和2.目的：确定S-SOX 5在男性生殖细胞中调控的靶基因。 这些研究将有助于阐明控制分化的组合转录因子密码 和哺乳动物雄性生殖细胞的结构转化。为实现这一目标而开发的工具 拟议的研究将使我们能够将该项目扩展到RO1应用，以阐明转录 控制哺乳动物精子成熟的机制。

Motile cilia are present in the epithelial cells of brain ventricles, trachea, oviduct, and sperm flagella. They play important roles in vivo including maintaining cerebrospinal fluid (CSF) circulation, clearing particles and pathogens from the respiratory tract, and sperm motility. Defects in motile cilia result in multiple diseases such as hydrocephalus, situs inversus, male infertility and et al. Most motile cilia have a “9+2” axoneme. The shared structure of motile cilia in different tissues suggests that common regulatory mechanisms exist to govern expression of cilia/flagellar components. We hypothesize that expression of the genes essential for motile cilia structure/function are regulated by similar mechanisms so that the proteins are assembled into the motile cilia in a coordinated and timely manner. Sperm flagella are special motile cilia. Besides the core axoneme, other accessory structures are also assembled during spermiogenesis, the process of spermatid differentiation. During this phase, a number of genes essential for sperm flagella assembly are up-regulated. However, the transcriptional regulation of this suite of genes is poorly understood. By analyzing putative transcription factor binding sites in the promoter regions of genes that are essential for sperm flagella structure/function, we identified SOX5 as a putative key controller of cilia/flagellar genes. Sox-5 is a member of a family of genes that shows homology to the high motility group (HMG) box region of the testis determining gene, SRY. The mouse Sox5 gene encodes two major transcripts: the longer Sox5 isoform, originally named L-Sox5, but most authors refer it as Sox5; and a shorter isoform, S-Sox5. The first exon of the S-Sox5 transcript is a non-translated exon;, and it is not present in the L-Sox5 transcript. The translated 48 kDa S-SOX5 protein lacks the N-terminal half of the 84 kDa L-SOX5 protein. The two SOX5 proteins have different tissue distributions. L-SOX5 is expressed in multiple tissues, including the cartilage, heart, brain, kidney, lung, and skeletal muscle, but not in the testis, and it plays important roles in regulating processes of embryonic development and cell fate determination. S-SOX5 protein is only expressed in tissues with motile cilia, including the brain, lungs, and particularly in the testis. In the testis, it is localized in the nuclei of post-meiotic round spermatids. It has been shown that S-SOX5 regulates expression of several genes highly expressed in the testis. We hypothesize that S-SOX5 regulates expression of a suite of genes that are essential for sperm flagella formation and function. To test this hypothesis, we propose the following Specific Aims:1. To establish the critical the role of S-SOX5 in flagellogenesis and male fertility; and 2. To establish the target genes regulated by S-SOX5 in male germ cells. The proposed studies will help clarify the combinatorial transcription factor code that governs the differentiation and structural transformation of mammalian male germ cells. The tools that will be developed in pursuit of the proposed research will allow us to expand the project to a RO1 application to elucidate the transcriptional mechanisms that control mammalian sperm maturation.