Acroframosome-Dependent KIFC1 Facilitates Acrosome Formation during Spermatogenesis in the Caridean Shrimp Exopalaemon modestus

Cong-Cong Hou,Wan-Xi Yang,Vladimir N. Uversky

doi:10.1371/journal.pone.0076065

Abstract

BackgroundAcrosome formation and nuclear shaping are the main events in spermatogenesis. During spermiogenesis in Exopalaemon modestus, a unique microtubular structure called the acroframosome (AFS) forms in spermatids. The AFS links to a temporary organelle called the lamellar complex (LCx) leading to the formation of an everted umbrella-shaped acrosome and a dish-shaped nucleus in the mature sperm. These morphological changes require complex cell motility in which the C-terminal kinesin motor protein called KIFC1 is involved. In this study, we demonstrate that KIFC1 moves along the AFS and plays an important role in acrosome formation and nuclear shaping during spermatogenesis in E. modestus.Methodology/Principal FindingsWe cloned a 3125 bp complete cDNA of kifc1 from the testis of E. modestus by PCR. The predicted secondary and tertiary structures of E. modestus KIFC1 contain three domains: a) the C-terminus, b) the stalk region, and the c) N-terminusl. Semi-quantitative RT-PCR detected the expression of kifc1 mRNA in different tissues of E. modestus. In situ hybridization demonstrated the temporal and spatial expression profile of kifc1 during spermiogenesis. Western blot identified the expression of KIFC1 in different tissues of E. modestus, including the testis. Immunofluorescence localized KIFC1, tubulin, GM130, and mitochondria in order to elucidate their role during spermiogenesis in E. modestus.Conclusion/SignificanceOur results indicate that KIFC1 transports the Golgi complex, mitochondria, and other cellular components that results in acrosome formation and nuclear shaping in E. modestus. The KIFC1 transport function depends upon the microtubular structure called the acroframosome (AFS). This study describes some of the molecular mechanisms involved in the acrosome formation and nuclear shaping in E. modestus. In addition, this study may provide a model for studying the molecular mechanisms involved in spermatogenesis in other crustacean species and lead to a better understanding of the fertilization process in crustaceans.

Highlights

There are three types of motor proteins that convert chemical energy into mechanical energy and show cytoskeleton dependency
Conclusion/Significance: Our results indicate that KIFC1 transports the Golgi complex, mitochondria, and other cellular components that results in acrosome formation and nuclear shaping in E. modestus
There are numerous kinesin motor proteins involved in spermatogenesis [17,18,19,20,21,22,23,24], we focused on the C-terminal KIFC1 motor protein which belongs to the kinesin-14 subfamily with a highly conserved motor domain [25]

Summary

Introduction

There are three types of motor proteins that convert chemical energy into mechanical energy and show cytoskeleton dependency. Kinesin and dynein show microtubule dependency and participate in morphological changes and organelle/vesicle transport [1,2,3,4]. Neurons undergo morphological changes during development similar to the morphological changes during spermatogenesis [1,6,7] In this regard, the KIF17 neuron-specific motor protein transports neurosecretory vesicles containing the N-methyl-Daspartate (NMDA) receptor 2B (NR2B subunit) along microtubules during neuronal morphogenesis [8]. The AFS links to a temporary organelle called the lamellar complex (LCx) leading to the formation of an everted umbrella-shaped acrosome and a dish-shaped nucleus in the mature sperm. These morphological changes require complex cell motility in which the C-terminal kinesin motor protein called KIFC1 is involved. We demonstrate that KIFC1 moves along the AFS and plays an important role in acrosome formation and nuclear shaping during spermatogenesis in E. modestus

Methods

Findings

Discussion

Conclusion