Purinergic signaling networks in the testis – insight into the role(s) of peritubular cells

睾丸产生精子和睾丸激素。精子发生在生精小管中，睾丸激素由间质细胞产生。精子发生是人体内最复杂但最不为人所知的发育过程之一。有关协调这些细胞转化事件的生理机制和精巢内精子运输的机械性信息很少。同样，莱迪格细胞的动态平衡也没有得到很好的理解。我们共同研究的长期目标是对睾丸信号在健康和疾病中的作用获得详细的机械性见解。我们主要研究睾丸小管周围细胞(TPC)。TPC位于生精小管和间质间隔室的交界处，是这两个单位功能的关键贡献者。它们有助于精原干细胞和睾丸免疫监测，然而，TPC在睾丸生理学中扮演的复杂角色仍然不清楚。在之前的资金支持期间，我们发现嘌呤能信号以TPC为靶标，并调节不同的功能。细胞外的三磷酸腺苷引起协调收缩，为精子运输提供推动力，而三磷酸腺苷代谢产物(特别是腺苷)在睾丸和TPC中起促炎作用。初步研究表明，腺苷可能进一步作为一种分子参与间质细胞的动态平衡。这些关键发现突出了我们合作努力的两个合乎逻辑的下一步：首先，我们需要了解依赖嘌呤的TPC收缩的机制基础，无论是在单细胞水平还是TPC网络水平。其次，我们必须扩大我们的分析范围，包括ATP代谢物，并不仅考虑它们在精子运输中的作用，还考虑它们在睾丸免疫学/细胞动态平衡中的作用。在这里，我们提出了一个互补的联合努力来阐明睾丸的嘌呤能信号。我们将利用已建立的工具库并对其进行扩展，以解决人类和小鼠TPC培养、器官型睾丸培养、小鼠活体模型中的这些主题，受益于一种新的活体成像平台。我们相信，这些研究将产生丰富的新信息，可能对开发男性避孕药(干扰精子运输)以及诊断和治疗特发性男性不育或性腺功能低下症(干扰炎症/间质细胞稳态)具有潜在的重要意义。基于我们的协作记录和一整套协同的方法，我们非常适合实现本提案中概述的雄心勃勃的目标。

The testis produces sperm and testosterone. Spermatogenesis takes place in the seminiferous tubules and testosterone is produced by interstitial Leydig cells. Spermatogenesis ranks among the most complex, yet least understood developmental processes in the body. Mechanistic information on the physiological machinery that orchestrates these cell transformation events and on intratesticular sperm transport, is sparse. Likewise, Leydig cell homeostasis is not well understood. The long-term goal of our joint research efforts is to gain detailed mechanistic insights into the roles of testicular signaling in both health and disease. We focus on testicular peritubular cells (TPCs). Strategically located at the interface of the seminiferous tubules and the interstitial compartment, TPCs emerge as crucial contributors to the functions of either unit. They contribute to the spermatogonial stem cell niche and testicular immune surveillance, however, the complex roles that TPCs play in testicular physiology, remain poorly defined. During the previous funding period, we showed that purinergic signals target TPCs and mediate distinct functions. While extracellular ATP causes coordinated contractions that provide the propulsive force for sperm transport, ATP metabolites (especially adenosine) serve pro-inflammatory functions in testis and TPCs. Pilot studies indicate that adenosine may further act as a molecule involved in Leydig cell homeostasis. These key findings highlight the two logical next steps for our collaborative endeavor: First, we need to understand the mechanistic basis of purine-dependent TPC contractions, both on the single cell and the TPC network level. Second, we must broaden our analytic scope to include ATP metabolites and consider their roles not only in sperm transport, but also in testis immunology/cellular homeostasis. Here, we propose a complementary joint effort to elucidate testicular purinergic signaling. We will employ the established repertoire of tools and extend it, in order to address these topics in human and mouse TPC cultures, organotypic testis cultures, mouse in vivo models, benefitting from a novel intravital imaging platform. We believe that these studies will generate a wealth of novel information that may bear potential importance for development of male contraceptives (interference with sperm transport), as well as for diagnosis and treatment of idiopathic male infertility or hypogonadism, respectively (interference with inflammation/ Leydig cell homeostasis). Based on our collaborative track record and synergistic sets of methods, we are ideally suited to tackle the ambitious goals outlined in this proposal.