Poc1B and Sas-6 Function Together during the Atypical Centriole Formation in Drosophila melanogaster.

Kyoung H Jo,Sushil Khanal,Emily L Fishman,Alaina N Curry,Ankit Jaiswal,Tomer Avidor-Reiss

doi:10.3390/cells8080841

Abstract

Insects and mammals have atypical centrioles in their sperm. However, it is unclear how these atypical centrioles form. Drosophila melanogaster sperm has one typical centriole called the giant centriole (GC) and one atypical centriole called the proximal centriole-like structure (PCL). During early sperm development, centriole duplication factors such as Ana2 and Sas-6 are recruited to the GC base to initiate PCL formation. The centriolar protein, Poc1B, is also recruited at this initiation stage, but its precise role during PCL formation is unclear. Here, we show that Poc1B recruitment was dependent on Sas-6, that Poc1B had effects on cellular and PCL Sas-6, and that Poc1B and Sas-6 were colocalized in the PCL/centriole core. These findings suggest that Sas-6 and Poc1B interact during PCL formation. Co-overexpression of Ana2 and Sas-6 induced the formation of ectopic particles that contained endogenous Poc1 proteins and were composed of PCL-like structures. These structures were disrupted in Poc1 mutant flies, suggesting that Poc1 proteins stabilize the PCL-like structures. Lastly, Poc1B and Sas-6 co-overexpression also induced the formation of PCL-like structures, suggesting that they can function together during the formation of the PCL. Overall, our findings suggest that Poc1B and Sas-6 function together during PCL formation.

Highlights

The centrosome is an organelle composed of two centrioles and pericentriolar material (PCM) [1].Most animal cells have centrosomes that serve as major microtubule organizing centers (MTOCs).In dividing cells, the centrosome serves as an microtubule-organizing center (MTOC) to assist in cell polarity and proper segregation of chromosomes
To determine the timing of Poc1B localization to the proximal centriole-like structure (PCL), we selected the earliest stage in spermiogenesis, when PCL is first labeled by Ana2, Sas-6, and Sas-4 tagged with GFP
Ana1 was only localized to the giant centriole (GC) and Ana2, Sas-6, Poc1B, and Sas-4 were localized to the PCL in early round spermatids (Figure 1A–D)

Summary

Introduction

The centrosome is an organelle composed of two centrioles and pericentriolar material (PCM) [1].Most animal cells have centrosomes that serve as major microtubule organizing centers (MTOCs).In dividing cells, the centrosome serves as an MTOC to assist in cell polarity and proper segregation of chromosomes. Most animal cells have centrosomes that serve as major microtubule organizing centers (MTOCs). The centriole serves as a basal body to form a cilia or flagellum, which are important for cellular signaling and motility [2]. Centrioles are mainly recognized by their typical barrel-shaped structure consisting of microtubules organized in a nine-fold symmetry as observed by electron microscopy. We refer to this structure as a “typical centriole” as certain cells have centrioles with a distinct structure that is atypical. The atypical centriole, the proximal centriole-like structure (PCL), is made of an electron-dense material (PCL wall) surrounding a tubule-like structure (PCL tubule) in the center [6,8].

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Conclusion