Ramesh Navyashree A, Box Allison M, Buttitta Laura A
Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, USA.
bioRxiv. 2024 Aug 13:2024.08.12.607650. doi: 10.1101/2024.08.12.607650.
The Ejaculatory duct (ED) is a secretory tissue of the somatic male reproductive system. The ED is involved in the secretion of seminal fluid components and ED-specific antimicrobial peptides that aid in fertility and the female post-mating response. The ED is composed of secretory epithelial cells surrounded by a layer of innervated contractile muscle. The ED grows in young adult males during the first 24h post-eclosion, but the cell cycle status of the ED secretory cells and the role of post-eclosion ED growth have been unexplored. Here, we show that secretory cells of the adult ED undergo variant cell cycles lacking mitosis called the endocycle, that lead to an increase in the cell and organ size of the ED post eclosion. The cells largely exit the endocycle by day 3 of adulthood, when the growth of the ED ceases, resulting in a tissue containing cells of ploidies ranging from 8C-32C. The size of the ED directly correlates with the ploidy of the secretory cells, with additional ectopic endocycles increasing organ size. When endoreplication is compromised in ED secretory cells, it leads to reduced organ size, reduced protein synthesis and compromised fertility. We provide evidence that the growth and endocycling in the young adult male ED is dependent on Juvenile hormone (JH) signaling and we suggest that hormone-induced early adult endocycling is required for optimal fertility and function of the ED tissue. We propose to use the ED as a post-mitotic tissue model to study the role of polyploidy in regulating secretory tissue growth and function.
射精管（ED）是男性体细胞生殖系统的一个分泌组织。射精管参与精液成分和射精管特异性抗菌肽的分泌，这些物质有助于生育和雌性的交配后反应。射精管由分泌上皮细胞组成，周围环绕着一层有神经支配的收缩肌。射精管在羽化后24小时内在年轻成年雄性中生长，但射精管分泌细胞的细胞周期状态以及羽化后射精管生长的作用尚未得到探索。在这里，我们表明成年射精管的分泌细胞经历了一种缺乏有丝分裂的变体细胞周期，称为内复制周期，这导致羽化后射精管的细胞和器官大小增加。在成年期第3天，当射精管停止生长时，细胞大多退出内复制周期，形成一个包含倍性从8C到32C的细胞的组织。射精管的大小与分泌细胞的倍性直接相关，额外的异位内复制周期会增加器官大小。当射精管分泌细胞的核内复制受损时，会导致器官大小减小、蛋白质合成减少和生育能力受损。我们提供的证据表明，年轻成年雄性射精管的生长和内复制周期依赖于保幼激素（JH）信号传导，并且我们认为激素诱导的成年早期内复制周期对于射精管组织的最佳生育能力和功能是必需的。我们建议将射精管用作有丝分裂后组织模型，以研究多倍体在调节分泌组织生长和功能中的作用。
