Boateng Ruby, Nguyen Ken C Q, Hall David H, Golden Andy, Allen Anna K
Department of Biology, Howard University, Washington, DC 20059, USA.
Center for C. elegans Anatomy, Albert Einstein College of Medicine, New York, NY 10461, USA.
Dev Biol. 2017 Sep 1;429(1):306-320. doi: 10.1016/j.ydbio.2017.06.015. Epub 2017 Jun 23.
RNA-binding proteins (RBPs) are essential regulators of gene expression that act through a variety of mechanisms to ensure the proper post-transcriptional regulation of their target RNAs. RBPs in multiple species have been identified as playing crucial roles during development and as having important functions in various adult organ systems, including the heart, nervous, muscle, and reproductive systems. ETR-1, a highly conserved ELAV-Type RNA-binding protein belonging to the CELF/Bruno protein family, has been previously reported to be involved in C. elegans muscle development. Animals depleted of ETR-1 have been previously characterized as arresting at the two-fold stage of embryogenesis. In this study, we show that ETR-1 is expressed in the hermaphrodite somatic gonad and germ line, and that reduction of ETR-1 via RNA interference (RNAi) results in reduced hermaphrodite fecundity. Detailed characterization of this fertility defect indicates that ETR-1 is required in both the somatic tissue and the germ line to ensure wild-type reproductive levels. Additionally, the ability of ETR-1 depletion to suppress the published WEE-1.3-depletion infertility phenotype is dependent on ETR-1 being reduced in the soma. Within the germline of etr-1(RNAi) hermaphrodite animals, we observe a decrease in average oocyte size and an increase in the number of germline apoptotic cell corpses as evident by an increased number of CED-1::GFP and acridine orange positive apoptotic germ cells. Transmission Electron Microscopy (TEM) studies confirm the significant increase in apoptotic cells in ETR-1-depleted animals, and reveal a failure of the somatic gonadal sheath cells to properly engulf dying germ cells in etr-1(RNAi) animals. Through investigation of an established engulfment pathway in C. elegans, we demonstrate that co-depletion of CED-1 and ETR-1 suppresses both the reduced fecundity and the increase in the number of apoptotic cell corpses observed in etr-1(RNAi) animals. Combined, this data identifies a novel role for ETR-1 in hermaphrodite gametogenesis and in the process of engulfment of germline apoptotic cell corpses.
RNA结合蛋白（RBPs）是基因表达的重要调节因子，它们通过多种机制发挥作用，以确保对其靶RNA进行适当的转录后调控。多个物种中的RBPs已被确定在发育过程中发挥关键作用，并在包括心脏、神经、肌肉和生殖系统在内的各种成体器官系统中具有重要功能。ETR-1是一种高度保守的ELAV型RNA结合蛋白，属于CELF/Bruno蛋白家族，此前已有报道称其参与秀丽隐杆线虫的肌肉发育。先前已将缺乏ETR-1的动物表征为在胚胎发育的二倍体阶段停滞。在本研究中，我们表明ETR-1在雌雄同体的体细胞性腺和生殖系中表达，并且通过RNA干扰（RNAi）降低ETR-1会导致雌雄同体的繁殖力下降。对这种生育缺陷的详细表征表明，在体细胞组织和生殖系中都需要ETR-1来确保野生型的生殖水平。此外，ETR-1缺失抑制已发表的WEE-1.3缺失不育表型的能力取决于ETR-1在体细胞中的减少。在etr-1（RNAi）雌雄同体动物的生殖系中，我们观察到平均卵母细胞大小减小，并且生殖系凋亡细胞尸体数量增加，这通过CED-1::GFP和吖啶橙阳性凋亡生殖细胞数量的增加得以体现。透射电子显微镜（TEM）研究证实了ETR-1缺失动物中凋亡细胞的显著增加，并揭示了etr-1（RNAi）动物中体细胞性腺鞘细胞未能正确吞噬死亡的生殖细胞。通过对线虫中已建立的吞噬途径的研究，我们证明CED-1和ETR-1的共同缺失抑制了在etr-1（RNAi）动物中观察到的繁殖力下降和凋亡细胞尸体数量的增加。综合来看，这些数据确定了ETR-1在雌雄同体配子发生以及生殖系凋亡细胞尸体吞噬过程中的新作用。
