ACTN4 Mediates SEPT14 Mutation-Induced Sperm Head Defects.

Yu-Hua Lin,Ying-Hung Lin,Ya-Yun Wang,Chia-Yen Huang,Hsuan-Che Liu,Chying-Chyuan Chan,Chih-Chun Ke,Tsung-Hsuan Lai,Wei-Chi Ku

doi:10.3390/biomedicines8110518

Abstract

Septins (SEPTs) are highly conserved GTP-binding proteins and the fourth component of the cytoskeleton. Polymerized SEPTs participate in the modulation of various cellular processes, such as cytokinesis, cell polarity, and membrane dynamics, through their interactions with microtubules, actin, and other cellular components. The main objective of this study was to dissect the molecular pathological mechanism of SEPT14 mutation-induced sperm head defects. To identify SEPT14 interactors, co-immunoprecipitation (co-IP) and nano-liquid chromatography-mass spectrometry/mass spectrometry were applied. Immunostaining showed that SEPT14 was significantly localized to the manchette structure. The SEPT14 interactors were identified and classified as (1) SEPT-, (2) microtubule-, (3) actin-, and (4) sperm structure-related proteins. One interactor, ACTN4, an actin-holding protein, was selected for further study. Co-IP experiments showed that SEPT14 interacts with ACTN4 in a male germ cell line. SEPT14 also co-localized with ACTN4 in the perinuclear and manchette regions of the sperm head in early elongating spermatids. In the cell model, mutated SEPT14 disturbed the localization pattern of ACTN4. In a clinical aspect, sperm with mutant SEPT14, SEPT14A123T (p.Ala123Thr), and SEPT14I333T (p.Ile333Thr), have mislocalized and fragmented ACTN4 signals. Sperm head defects in donors with SEPT14 mutations are caused by disruption of the functions of ACTN4 and actin during sperm head formation.

Highlights

Over the course of sperm head shaping, SEPT14 gradually shaping, SEPT14 gradually became concentrated in the narrow manchette. These became concentrated in the narrow manchette (Figure 1B,C). These findings suggest that SEPT14 is findings suggest
SEPT14 interacts and co-localizes murine spermiogenesis (Figure 3B). These findings suggest that SEPT14 interacts and co-localizes with
The human sperm with the mutated SEPT14 interrupts ACTN4 localization in on these findings, we propose that SEPT14/ACTN4 complexes play a critical role in sperm head vivo

Summary

Introduction

The known major causes of male infertility include anatomic abnormalities, endocrine defects, immunologic dysfunction, infection,. Y chromosome deletion, environmental exposure, and gene mutations [3,4,5]. Semen analysis is a critical tool for identifying the cause of infertility, and semen can be classified as normozoospermia, oligozoospermia, asthenozoospermia, teratozoospermia, or azoospermia [6]. Teratozoospermia is frequently accompanied by sperm DNA defects and can have negative effects on pregnancy outcomes and embryo progress, including recurrent spontaneous abortion, pregnancy failure, and lower live birth rates [7,8,9,10,11,12,13]. Several mutations in certain genes have been linked to teratozoospermia, including

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