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

睾丸产生精子和睾丸素。精子发生在精小管中，睾酮由间质间质细胞产生。精子发生是人体中最复杂、却又最不为人所知的发育过程之一。关于协调这些细胞转化事件和睾丸内精子运输的生理机制的机制信息很少。同样，间质细胞的稳态也没有得到很好的理解。我们共同研究的长期目标是获得睾丸信号在健康和疾病中的作用的详细机制见解。我们关注睾丸小管周围细胞（TPCs）。TPCs战略性地位于精小管和间质室的界面，对这两个单位的功能都起着至关重要的作用。它们有助于精原干细胞生态位和睾丸免疫监视，然而，TPCs在睾丸生理学中发挥的复杂作用仍然不清楚。在之前的资助期间，我们发现嘌呤能信号靶向TPCs并介导不同的功能。细胞外ATP引起协调收缩，为精子运输提供推进力，ATP代谢物（尤其是腺苷）在睾丸和TPCs中具有促炎功能。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稳态。这些关键发现突出了我们合作努力的两个逻辑下一步：首先，我们需要了解嘌呤依赖性TPC收缩的机制基础，包括单细胞和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，并考虑它们不仅在精子运输中的作用，而且在睾丸免疫/细胞稳态中的作用。在这里，我们提出一个互补的联合努力来阐明睾丸嘌呤能信号。我们将利用已建立的工具库并扩展它，以便在人类和小鼠TPC培养，器官型睾丸培养，小鼠体内模型中解决这些问题，受益于新的活体成像平台。我们相信这些研究将产生丰富的新信息，这些信息可能对男性避孕药的开发（干扰精子运输）以及特发性男性不育或性腺功能低下的诊断和治疗（干扰炎症/间质细胞稳态）具有潜在的重要性。基于我们的合作记录和一系列协同方法，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.