Biology of the Blood-Testis Barrier

血睾屏障的生物学

• 批准号: 9113053
• 负责人: C. Yan Cheng
• 金额: $ 37.14万
• 依托单位: POPULATION COUNCIL
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-02-01 至 2019-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9113053
• 关键词: Actin-Binding Protein; Actins; Acute; Address; Adherens Junction; Adhesives; Apical; Basement membrane; Biological; Biology; Blood; Blood-Testis Barrier; Bundling; Cadmium; Cell Adhesion; Cell membrane; Collagen; Complex; Contraceptive Agents; Developing Countries; Development; Diethylstilbestrol; Dose; Endoplasmic Reticulum; Endosomes; Epidermal Growth Factor Receptor Pathway Substrate 8; Epithelial; Epithelium; Event; F-Actin; Fertility; Functional disorder; Gelatinase A; Gelatinase B; Generations; Genes; Genetic Models; Grant; Health; Homeostasis; In Vitro; Intercellular Junctions; Journals; Knock-out; Laboratories; Laminin; Lead; Lifting; Light; Male Contraceptive Agents; Male Infertility; Mammals; Mediating; Meiosis; Metalloproteases; MicroRNAs; Microfilaments; Molecular; Mus; Nature; Neonatal; Neurons; Peer Review; Peptides; Production; Proteins; Publications; RNA Interference; Rattus; Regulation; Research; Research Personnel; Rodent; Role; Seminiferous tubule structure; Small Interfering RNA; Small RNA; Spermatids; Spermatocytes; Spermatogenesis; Staging; Steroids; Structure; Techniques; Testis; Testosterone; Tissues; Toxic Environmental Substances; Training; Wiskott-Aldrich Syndrome; autocrine; bisphenol A; cytokine; design; genetic regulatory protein; in vivo; insight; knock-down; male; men; novel; novel therapeutic intervention; overexpression; phthalates; piRNA; polymerization; protein transport; public health relevance; reproductive; research study; sertoli cell; small molecule; spatiotemporal; sperm cell; spermatogenic epithelium structure; therapeutic development; toxicant; xenoestrogen

DESCRIPTION (provided by applicant): In the mammalian testis, spermatogenesis takes place in the epithelium of the seminiferous tubule, the functional unit that produces millions of spermatozoa daily. The blood-testis barrier (BTB), located near the basement membrane (BM) of the seminiferous epithelium, confers gate-keeper and the fence function, which restricts the paracellular and transcellular transport of harmful substances such as toxicants across the barrier, respectively, to maintain spermatogenesis. The BTB also physically divides the seminiferous epithelium into a basal and an adluminal compartment; thus, meiosis I and II, and post-meiotic spermatid development take place in a specialized microenvironment (i.e., the adluminal compartment) behind the BTB. The BTB is one of the tightest blood-tissue barriers in mammals since cell junctions at the BTB are reinforced by bundles of actin filaments that lie perpendicular to apposing Sertoli cell plasma membranes, which are only found in the testis. However, the BTB is a dynamic structure, undergoing extensive restructuring at stage VIII of the epithelial cycle so that preleptotene spermatocytes can cross the BTB and enter the adluminal compartment for further development. It is now well established that a functional BTB is crucial for spermatogenesis. Studies completed in the past grant period have shown that BTB function is regulated by biologically active peptides released (i) at the apical ectoplasmic specialization (apical ES, a testis-specific adherens junction at the Sertoli-spermatid interface), and (ii) at th basement membrane (BM) mediated by a functional axis designated the apical ES-BTB-BM axis. In short, biologically active fragments of laminin and collagen chains released at the apical ES and the BM, respectively, act as autocrine factors to regulate BTB function in this axis. Herein, we will continue this important research to understand the underlying molecular mechanism(s) that regulates BTB function. First, we will unravel the mechanism(s) by which these fragments regulate Sertoli cell adhesion and BTB restructuring via their effects on the F-actin network at the BTB, such as actin binding and regulatory proteins. We will also examine the involvement of endosome-mediated protein trafficking and small regulatory RNAs in these events using state-of-the-art techniques and approaches. Second, we will identify the biological significance of biomolecules, such as cytokines, steroids and matrix metalloproteases, in regulating the stage-specific production of these bioactive peptides during the epithelial cycle of spermatogenesis. These findings will have a significant impact in understanding the biology of BTB in spermatogenesis. More important, these findings will shed new light on the development of novel reversible non-hormonal contraceptives for men. For instance, peptides derived from the apical ES and BM can be developed into contraceptives to perturb BTB function and impair spermatogenesis. Additionally, these findings can lead to the development of new therapeutic approaches to interfere with toxicant-induced male reproductive dysfunction, which is one of the leading causes of the decline in male fertility. For instance, the environmental toxicant cadmium mediates its effects at the BTB to induce male reproductive dysfunction; these findings provide crucial information in the design and synthesis of small molecules that either reverse or block cadmium-induced BTB disruption that leads to male infertility.

描述（由申请方提供）：在哺乳动物睾丸中，精子发生发生在生精小管上皮中，生精小管是每天产生数百万精子的功能单位。血睾屏障（blood-testis barrier，BTB）位于生精上皮基底膜（basement membrane，BM）附近，具有守门和栅栏功能，分别限制有害物质（如有毒物质）的跨细胞转运和跨细胞转运，以维持精子发生。BTB还在物理上将生精上皮分为基底和近腔室;因此，减数分裂I和II以及减数分裂后精子细胞发育发生在专门的微环境中（即，近腔室）在BTB后面。BTB是哺乳动物中最紧密的血液组织屏障之一，因为BTB处的细胞连接被肌动蛋白丝束加强，肌动蛋白丝束垂直于仅在睾丸中发现的并列支持细胞质膜。然而，BTB是一个动态的结构，在上皮细胞周期的第八阶段进行广泛的重组，使前细线期精母细胞可以穿过BTB，进入近腔室进一步发展。现在已经确定，功能性BTB对精子发生至关重要。在过去的资助期内完成的研究表明，BTB功能受以下生物活性肽的调节：（i）在顶端外质特化（顶端ES，支持细胞-精子细胞界面处的睾丸特异性粘附连接），和（ii）在基膜（BM），由指定为顶端ES-BTB-BM轴的功能轴介导。简而言之，层粘连蛋白和胶原蛋白链的生物活性片段在顶端释放， ES和BM分别作为自分泌因子调节BTB在该轴中的功能。在此，我们将继续这项重要的研究，以了解调节BTB功能的潜在分子机制。首先，我们将阐明这些片段通过其对BTB处的F-肌动蛋白网络的影响（如肌动蛋白结合和调节蛋白）来调节支持细胞粘附和BTB重组的机制。我们还将使用最先进的技术和方法研究内体介导的蛋白质运输和小调控RNA在这些事件中的参与。其次，我们将确定生物分子，如细胞因子，类固醇和基质金属蛋白酶，在调节这些生物活性肽在上皮细胞周期的阶段特异性生产的生物学意义。 精子发生这些发现将对理解BTB在精子发生中的生物学产生重大影响。更重要的是，这些发现将为开发新型可逆的男性非激素避孕药提供新的思路。例如，来自顶端ES和BM的肽可以开发成避孕药，以干扰BTB功能并损害精子发生。此外，这些发现可以导致开发新的治疗方法来干扰毒物诱导的男性生殖功能障碍，这是男性生育能力下降的主要原因之一。例如，环境毒物镉介导其对BTB的影响，诱导男性生殖功能障碍;这些发现为设计和合成小分子提供了关键信息，这些小分子可以逆转或阻断镉诱导的BTB破坏，导致男性不育。