Functional Analysis of Hydrolethalus Syndrome Protein HYLS1 in Ciliogenesis and Spermatogenesis in Drosophila.

Yanan Hou,Yingying Zhang,Qing Wei,Huicheng Chen,Ying Peng,Yi Guo,Jinghua Hu,Zhimao Wu

doi:10.3389/fcell.2020.00301

Abstract

Cilia and flagella are conserved subcellular organelles, which arise from centrioles and play critical roles in development and reproduction of eukaryotes. Dysfunction of cilia leads to life-threatening ciliopathies. HYLS1 is an evolutionarily conserved centriole protein, which is critical for ciliogenesis, and its mutation causes ciliopathy–hydrolethalus syndrome. However, the molecular function of HYLS1 remains elusive. Here, we investigated the function of HYLS1 in cilia formation using the Drosophila model. We demonstrated that Drosophila HYLS1 is a conserved centriole and basal body protein. Deletion of HYLS1 led to sensory cilia dysfunction and spermatogenesis abnormality. Importantly, we found that Drosophila HYLS1 is essential for giant centriole/basal body elongation in spermatocytes and is required for spermatocyte centriole to efficiently recruit pericentriolar material and for spermatids to assemble the proximal centriole-like structure (the precursor of the second centriole for zygote division). Hence, by taking advantage of the giant centriole/basal body of Drosophila spermatocyte, we uncover previously uncharacterized roles of HYLS1 in centriole elongation and assembly.

Highlights

Centrioles are small cylindrical cellular organelles typically composed of ninefold symmetric triplet microtubules, which perform two important functions, building centrosome and templating cilia (Bettencourt-Dias and Glover, 2007; Nigg and Stearns, 2011; Conduit et al, 2015)
The antibody was validated by the following facts: anti-HYLS1 staining showed similar localization pattern as HYLS1-green fluorescent protein (GFP) (Figure 1 and Supplementary Figure S2); the staining signal was completely lost in hyls1 deletion mutants (Figure 3D)
We demonstrated that the centriole/basal body localization of HYLS1 and its role in ciliary function are highly conserved in Drosophila

Summary

Introduction

Centrioles are small cylindrical cellular organelles typically composed of ninefold symmetric triplet microtubules, which perform two important functions, building centrosome and templating cilia (Bettencourt-Dias and Glover, 2007; Nigg and Stearns, 2011; Conduit et al, 2015). Only the mother centriole, but not the daughter centriole, has the ability to form cilia, because only the mother centriole has distal appendage (DA) structures, which is critical for ciliogenesis initiation by mediating centrioles membrane docking. DAs are converted into transition fibers (TFs), one of the conspicuous structures at the cilia base. In invertebrates, such as Caenorhabditis elegans (C. elegans) and Drosophila, centrioles lack DAs, but TFs, at least functional homologous structures, are formed during ciliogenesis. Transition fibers, together with the transition zone (TZ), act as the ciliary gate to control the ciliary protein entry in the context of cilia (Reiter et al, 2012; Takao and Verhey, 2016; Garcia-Gonzalo and Reiter, 2017). Despite that great progress has been made in understanding the molecular components of DA/TF and their function in ciliogenesis, how such appendages are uniquely assembled from the distal end of mother centriole remains largely as an unsolved mystery (Tanos et al, 2013; Ye et al, 2014; Yang et al, 2018)

Methods

Results

Conclusion