A transcription factor DAF-5 functions in Haemonchus contortus development

Wenda Di,Li He,Min Hu,Fangfang Li,Lisa Ye,Caixian Zhou,Lu Liu,Chunqun Wang,Jian Chen

doi:10.1186/s13071-021-05036-2

Abstract

BackgroundAbnormal dauer formation gene (daf-5), located downstream of the DAF-7 signalling pathway, mainly functions in dauer formation and reproductive processes in the free-living nematode Caenorhabditis elegans. Although the structure and function of daf-5 have been clarified in C. elegans, they still remain totally unknown in Haemonchus contortus, a socio-economically important parasitic nematode of gastric ruminants.MethodsA homologue of daf-5, Hc-daf-5, and its inferred product (Hc-DAF-5) in H. contortus were identified and characterized in this study. Then the transcriptional profiles of Hc-daf-5 and the anatomical expression of Hc-DAF-5 in H. contortus were studied using an integrated molecular approach. RNA interference (RNAi) was performed to explore its function in transition from the exsheathed third-stage larvae (xL3s) to the fourth-stage larvae (L4s) in vitro. Finally, the interaction between Hc-DAF-5 and Hc-DAF-3 (a co-Smad) was detected by bimolecular fluorescence complementation (BiFc) in vitro.ResultsIt was shown that Hc-DAF-5 was a member of the Sno/Ski superfamily. Hc-daf-5 was transcribed in all developmental stages of H. contortus, with significant upregulation in L3s. Native Hc-DAF-5 was localized in the reproductive organs, cuticle, and intestine via immunohistochemistry. RNAi revealed that specific small interfering RNAs (siRNAs) could retard xL3 development. In addition, the interaction between Hc-DAF-5 and Hc-DAF-3 indicated that the SDS box of Hc-DAF-5 was dispensable for the binding of Hc-DAF-5 to Hc-DAF-3, and the MH2 domain was the binding region between Hc-DAF-3 and Hc-DAF-5.ConclusionsIn summary, these findings show that Hc-daf-5 functions in the developmental processes of H. contortus, and this study is the first attempt to characterize the daf-5 gene in parasitic nematodes.Graphical abstract

Highlights

Abnormal dauer formation gene, located downstream of the DAF-7 signalling pathway, mainly functions in dauer formation and reproductive processes in the free-living nematode Caenorhabditis elegans
All RNA samples were treated with DNase I to remove genomic DNA, and their integrity and yields were verified by electrophoresis and spectrophotometric analysis
The predicted protein sequence of Hc-DAF-5 was aligned with homologues from five nematodes and five other metazoans

Summary

Introduction

Abnormal dauer formation gene (daf-5), located downstream of the DAF-7 signalling pathway, mainly functions in dauer formation and reproductive processes in the free-living nematode Caenorhabditis elegans. For the transforming growth factor-β (TGF-β) signalling pathway in vertebrates, activation of receptors causes downstream R-Smad phosphorylation, which allows the latter to form an active Smad transcriptional complex with co-Smads. The function of this complex is affected positively or negatively by interaction with cofactor, co-activator, and co-repressor molecules, which regulates cellular processes such as proliferation, differentiation, and apoptosis [2]. As downstream components of the TGF-β signalling pathway, the Ski. Di et al Parasites Vectors (2021) 14:529 proto-oncoprotein family of co-repressors, including c-Ski and SnoN, play important roles in tightly controlled repression of Smad-mediated transcriptional activation, and antagonize TGF-β signalling by binding to the Smad transcriptional complex, preventing their interaction with co-activators, and recruiting co-repressors [3]. The degradation or accumulation of Sno/Ski protein occurs depending on the context of the TGF-β signalling [4]

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