Pelota-interacting G protein Hbs1 is required for spermatogenesis in Drosophila

Zhaohui Li,Yang Xuan,Fu Yang,Rongwen Xi,Rui Zhao

doi:10.1038/s41598-019-39530-6

Abstract

Hbs1, which is homologous to the GTPase eRF3, is a small G protein implicated in mRNA quality control. It interacts with a translation-release factor 1-like protein Dom34/Pelota to direct decay of mRNAs with ribosomal stalls. Although both proteins are evolutionarily conserved in eukaryotes, the biological function of Hbs1 in multicellular organisms is yet to be characterized. In Drosophila, pelota is essential for the progression through meiosis during spermatogenesis and germline stem cell maintenance. Here we show that homozygous Hbs1 mutant flies are viable, female-fertile, but male-sterile, which is due to defects in meiosis and spermatid individualization, phenotypes that are also observed in pelota hypomorphic mutants. In contrast, Hbs1 mutants have no obvious defects in germline stem cell maintenance. We show that Hbs1 genetically interacts with pelota during spermatid individualization. Furthermore, Pelota with a point mutation on the putative Hbs1-binding site cannot substitute the wild type protein for normal spermatogenesis. These data suggest that Pelota forms a complex with Hbs1 to regulate multiple processes during spermatogenesis. Our results reveal a specific requirement of Hbs1 in male gametogenesis in Drosophila and indicate an essential role for the RNA surveillance complex Pelota-Hbs1 in spermatogenesis, a function that could be conserved in mammals.

Highlights

Spermatogenesis in Drosophila is initiated by the asymmetric divisions of germline stem cells (GSCs) that give rise to the respective differentiated gonialblasts, each of which undergoes four rounds of mitotic divisions to produce 16 spermatocytes
There was no sperm found in seminal vesicles (SV) and mutant SVs were much smaller than that in control flies. (Fig. 1C,D), suggesting that no mature sperm is formed in the absence of Hbs[1]
Our results suggest that Hbs[1] may collaborate with Pelo to regulate multiple processes during spermatogenesis in Drosophila, which is supported by several observations

Summary

Introduction

Spermatogenesis in Drosophila is initiated by the asymmetric divisions of germline stem cells (GSCs) that give rise to the respective differentiated gonialblasts, each of which undergoes four rounds of mitotic divisions to produce 16 spermatocytes. Dom[34] was found to interact with Hbs[1], originally uncovered in yeast as a suppressor of the growth defect in strains deficient for Hsp 70 proteins[5], and Hbs[1] was shown to promotes efficient cell growth and protein synthesis[6] Both Dom34p and Hbs[1] are identified as important factors in a mRNA quality control pathway named no-go decay, in which mRNAs with ribosomal stalls during translational elongation or at the 3′ end of mRNA are subjected to degradation by endonucleolytic cleavage[7,8,9,10]. In Drosophila, mutation in pelo causes loss of ovarian GSCs, in part as a result of compromised BMP signaling pathway activation[28] These observations indicate an evolutionarily conserved function of Pelo in GSCs and gonad development. The biological function of Hbs[1] and Pelo-Hbs[1] complex beyond female germline remains to be explored in multicellular organisms

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Results

Conclusion