The biology of blood-testis barrier dynamics

血睾屏障动力学的生物学

• 批准号: 8042680
• 负责人: C. Yan Cheng
• 金额: $ 29.08万
• 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 2014-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8042680
• 关键词: Address; Adult; Androgen Receptor; Androgens; Apical; Back; Basement membrane; Biochemical; Biochemistry; Biological; Biology; Blood-Testis Barrier; Cell Adhesion; Cell physiology; Cell surface; Cells; Cellular biology; Coculture Techniques; Collagen; Endocytosis; Endosomes; Epithelial; Epithelium; Extracellular Matrix; Extracellular Matrix Proteins; Gelatinase B; Germ Cells; Health; Homeostasis; In Vitro; Infertility; Integral Membrane Protein; Kinetics; Knockout Mice; Laboratories; Male Contraceptions; Male Contraceptive Agents; Male Infertility; Matrix Metalloproteinases; Mediating; Meiosis; Membrane Proteins; Metalloproteases; Molecular; Molecular Biology; Mus; Peptide Hydrolases; Permeability; Pharmaceutical Preparations; Production; Property; Protease Inhibitor; Proteins; Rattus; Recombinants; Recycling; Regulation; Research; Research Personnel; Site; Spermatocytes; Spermatogenesis; Staging; Study models; TNF gene; Techniques; Testing; Testis; Testosterone; Tight Junctions; Time; Tissues; Transforming Growth Factors; Tumor Necrosis Factor-alpha; Work; base; cell motility; cytokine; design; in vitro Model; in vivo; inhibitor/antagonist; innovation; insight; late endosome; leydig interstitial cell; migration; mouse model; novel; novel strategies; occludin; public health relevance; sertoli cell; spermatogenic epithelium structure; tool; transcytosis

DESCRIPTION (provided by applicant): The long-term objective of this proposal is to understand the biology and regulation of blood-testis barrier (BTB) dynamics during spermatogenesis using the adult rat testis as a study model. Specifically, it seeks to unravel the mechanism(s) that maintains BTB integrity as preleptotene and leptotene spermatocytes traverse the BTB that occurs at stage VIII of the seminiferous epithelial cycle of spermatogenesis. This study is important since it answers an open question in the field regarding the biochemical and/or molecular mechanism(s) utilized by the testis that regulates the timely 'restructuring' of the BTB to permit spermatocyte transit while maintaining the immunological barrier function at the BTB. This information is also helpful to develop innovative approaches to design new drugs (e.g., male contraceptives that exert their effects by disrupting germ cell function in the seminiferous epithelium) that can be targeted to the seminiferous epithelium behind the BTB. Recent studies have shown that cytokines (e.g., tumor necrosis factor ?, TNF?, and transforming growth factor-?2/-3, TGF-?2 or -?3) have a disruptive effect on BTB integrity, whereas testosterone promotes BTB function, illustrating that the opposing effects of these molecules are crucial to maintain the timely "opening" and "closing" of the BTB during spermatogenesis while facilitating germ cell movement across the barrier. Since both TNF? and TGF-?3 are products of Sertoli and germ cells, and testosterone is a product of Leydig cells (but the androgen receptor resides mostly on the Sertoli cell), in the testis, it is likely that these molecules are released into the BTB microenvironment during spermatogenesis to regulate BTB dynamics. In this application, the P.I. will examine the hypothesis that TNF? regulates BTB dynamics via its effects on basement membrane proteins, such as collagens, proteases and protease inhibitors, which, in turn, regulates the steady-state levels of integral membrane proteins at the BTB. This will determine the status of the BTB to facilitate or prohibit the transit of preleptotene/leptotene spermatocytes across the barrier (Specific Aim 1). Furthermore, the P.I. will test the hypothesis that cytokines and testosterone mediate their opposing effects on the BTB via their differential actions on endocytosis, recycling, endosome-mediated intracellular degradation and transcytosis/relocation of integral membrane proteins at the BTB (Specific Aim 2). The proposed studies will be performed using cutting-edge techniques of biochemistry, molecular biology, and cell biology. The P.I. will also develop and characterize a novel in vitro model using Sertoli-germ cell cocultures to investigate the regulation of germ cell movement across the BTB, which can become a valuable research tool for investigators in the field. In short, this proposal addresses a long-standing mystery in spermatogenesis regarding the biology and regulation of the BTB during the epithelial cycle. PUBLIC HEALTH RELEVANCE: This project seeks to understand the mechanism(s) that regulates blood-testis barrier (BTB) dynamics during the seminiferous epithelial cycle of spermatogenesis using the adult rat testis as a study model. The BTB must `open' or `restructure' transiently during spermatogenesis to facilitate the transit of spermatocytes across the barrier. This, in turn, poses a unique opportunity to transport a drug, such as a male contraceptive that disrupts cell adhesion, behind the BTB to exert its effects, if the mechanism(s) that regulates the timely opening of the BTB is known. In short, this proposal seeks to understand the biology of BTB dynamics during spermatogenesis. It also offers new insight into: (i) developing novel approaches for male contraception, and (ii) the causes of unexplained male infertility.

描述（由申请人提供）：本提案的长期目标是利用成年大鼠睾丸作为研究模型，了解精子发生过程中血睾丸屏障（BTB）动力学的生物学和调控。具体地说，它试图揭示当prelepptotene和lepptotene精母细胞穿过BTB时维持BTB完整性的机制，BTB发生在精子发生的输精管上皮周期的第八阶段。这项研究很重要，因为它回答了一个悬而未决的问题，即睾丸利用的生化和/或分子机制来调节BTB的及时“重组”，以允许精母细胞运输，同时维持BTB的免疫屏障功能。这一信息也有助于开发创新的方法来设计新的药物（例如，男性避孕药通过破坏精子上皮中的生殖细胞功能来发挥其作用），这些药物可以靶向BTB后面的精子上皮。最近的研究表明，细胞因子(如肿瘤坏死因子？肿瘤坏死因子?转化生长因子-？2/-3, TGF - ?2还是-？3)破坏BTB的完整性，而睾酮则促进BTB的功能，说明这些分子的相反作用对于维持精子发生过程中BTB的及时“打开”和“关闭”，同时促进生殖细胞穿过屏障的运动至关重要。因为TNF？和TGF - ?3是支持细胞和生殖细胞的产物，睾酮是间质细胞的产物（但雄激素受体主要存在于支持细胞上），在睾丸中，这些分子很可能在精子发生过程中被释放到BTB微环境中，以调节BTB动力学。在本应用中，P.I.将检验TNF？通过其对基底膜蛋白（如胶原、蛋白酶和蛋白酶抑制剂）的影响来调节BTB动力学，而基底膜蛋白反过来又调节BTB中整体膜蛋白的稳态水平。这将决定BTB的状态，以促进或禁止prelepptotene / lepptotene精母细胞通过屏障（Specific Aim 1）。此外，P.I.将验证细胞因子和睾酮通过它们对BTB内吞作用、再循环、内核体介导的细胞内降解和整体膜蛋白的胞吞作用/再定位的不同作用介导它们对BTB的相反作用的假设（Specific Aim 2）。建议的研究将使用生物化学，分子生物学和细胞生物学的尖端技术进行。P.I.还将开发和表征一种新的体外模型，使用sertoli -生殖细胞共培养来研究生殖细胞在BTB中的运动调节，这将成为该领域研究人员的一个有价值的研究工具。简而言之，这一建议解决了精子发生中关于上皮细胞周期中BTB的生物学和调控的长期谜团。公共卫生相关性：本项目旨在了解在精子发生的精管上皮周期中调节血睾丸屏障（BTB）动力学的机制，以成年大鼠睾丸为研究模型。在精子发生过程中，BTB必须短暂地“打开”或“重组”，以促进精母细胞穿过屏障。反过来，这又提供了一个独特的机会来运输药物，如破坏细胞粘附的男性避孕药，在BTB背后发挥其作用，如果调节BTB及时开放的机制是已知的。简而言之，本研究旨在了解精子发生过程中BTB的生物学动态。它还提供了新的见解：(1)开发男性避孕的新方法，(2)不明原因的男性不育的原因。