高度保守的环形RNA在精子发生中的功能和调控机制

Circular RNA was discovered about 30 years ago, but it only caught the spotlight until recently when high throughput sequencing data revealed the widespread presence of this unique type of non-coding RNAs in diverse organisms and various tissues. The interest in its generation, physiological function and roles in human diseases was reignited. Testis was found to be one of the tissues with highest circular RNAs expression but little is known about their roles in the tissues or in reproduction. We have discovered circular RNAs from highly conserved reproductive gene—BOULE locus. These circular RNAs appear to be specifically expressed in the testis and exhibited a developmentally regulated expression pattern during spermatogenesis. Comparative analysis revealed the orthologous circular RNAs are present not only in mammalian species including human, mouse and pigs, but also in other vertebrates and all the way to fruit flies, making them one of most highly conserved and ancient circular RNAs known so far. Generation of knockout animals removing those circular RNAs implicate their potential roles in fertility. Detailed characterization of those knockout animals was proposed to determine the physiological function of circular RNA in fruit flies and mice, and to elucidate molecular mechanisms by which they regulate spermatogenesis.

环形RNA作为一种新的非编码RNA，虽距发现已有30年，但对其重要性的认识和研究才刚刚开始。目前环形RNA的生理功能尚不清楚。在小鼠中，发现环形RNA在睾丸中的表达丰度仅次于最高的脑组织，且这些环形RNA表达呈现一定的阶段特异性，提示环形RNA在精子发生中发挥重要的生物学功能。实验室前期研究发现一种外显子环形RNA, 从人、小鼠、猪一直到果蝇都存在，且其表达均呈现睾丸特异性，表明该外显子环形RNA高度保守和古老。 我们拟通过建立环形RNA敲除动物模型，阐明这个高度保守的生殖特异的环形RNA在精子发生中的生物学功能，揭示环形RNA调控精子发生发育的分子机制；并结合人、小鼠和果蝇睾丸的高通量测序，全面鉴定人精子发生过程中高度保守的环形RNA，为临床男性不育的诊断和治疗提供新的方向和理论依据。

环状RNAs(环状RNAs)是一种新型的非编码RNA，由一条单链RNA通过共价键形成的闭合的环状结构。虽然，环状RNA第一次发现是上世纪70年代，在植物中参与编Subviral agents，近年来环状RNA被发现普遍存在，并与疾病相关，但其生理作用和进化意义研究甚少。本项目鉴定和阐明了由一个从果蝇到人类保守的生殖特异的环状RNA的进化历史和在果蝇和小鼠育性调控中的作用。在热应激条件下，缺失circBoule RNAs后的果蝇显示出雄性生育能力下降,精子核异常率增高；circBoule RNAs敲除小鼠的精子显示出受精能力下降。进一步分析发现果蝇中的circBoul RNAs与热休克蛋白(HSPs)HSC4和HSP60C相互作用，小鼠精子中circBoule RNAs与HSPA2蛋白也存在相互作用关系。CircBoule RNAs是通过促进热休克蛋白的泛素化来调节其在精子发生中的水平来调控雄性的育性。我们进一步开拓了环状RNA在人精液和受精能力的研究，发现人circBoule RNAs与HSPA2之间的相互作用在人类精子中也是保守的。本项目揭示了circBoule RNAs在动物中生殖系统通过调控热激蛋白的降解来保护应激环境下的精子受精能力的生理机制，为研究男性不育的致病机理研究提供了崭新的思路，研究成果已经发表在Science Advance等有影响的国际期刊，受到广泛的关注。