Ring canals in the female germline of Drosophila melanogaster are supported by a robust filamentous actin (F-actin) cytoskeleton, setting them apart from ring canals in other species and tissues. Previous work has identified components required for the expansion of the ring canal actin cytoskeleton but has not identified the proteins responsible for F-actin recruitment or accumulation. Using a combination of CRISPR-Cas9 mediated mutagenesis and UAS-Gal4 overexpression, we show that HtsRC, a component specific to female germline ring canals, is both necessary and sufficient to drive F-actin accumulation. Absence of HtsRC in the germline resulted in ring canals lacking inner rim F-actin, while overexpression of HtsRC led to larger ring canals. HtsRC functions in combination with Filamin to recruit F-actin to ectopic actin structures in somatic follicle cells. Finally, we present findings which indicate that HtsRC expression and robust female germline ring canal expansion are important for high fecundity in fruit flies but dispensable for their fertility, a result which is consistent with our understanding of HtsRC as a newly evolved gene specific to female germline ring canals.

中文翻译：

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HtsRC 介导的 F-肌动蛋白积累在果蝇卵子发生过程中调节环管大小。


黑腹果蝇雌性种系中的环管由强大的丝状肌动蛋白（F-肌动蛋白）细胞骨架支撑，这使它们与其他物种和组织中的环管不同。先前的工作已经确定了环管肌动蛋白细胞骨架扩张所需的成分，但尚未确定负责 F-肌动蛋白募集或积累的蛋白质。通过结合 CRISPR-Cas9 介导的诱变和 UAS-Gal4 过表达，我们证明 HtsRC（女性种系环管特有的成分）对于驱动 F-肌动蛋白积累是必要且充分的。种系中 HtsRC 的缺失导致环管缺乏内缘 F-肌动蛋白，而 HtsRC 的过度表达导致环管更大。 HtsRC 与 Filamin 结合发挥作用，将 F-肌动蛋白募集到体细胞滤泡细胞的异位肌动蛋白结构中。最后，我们提出的研究结果表明，HtsRC 表达和强大的雌性种系环管扩张对于果蝇的高繁殖力很重要，但对于其繁殖力来说却是可有可无的，这一结果与我们对 HtsRC 作为雌性种系特异性的新进化基因的理解是一致的环形运河。