ORCID Profile
0000-0003-0260-7861
Current Organisation
Kumamoto University
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
Publisher: Cold Spring Harbor Laboratory
Date: 15-04-2022
DOI: 10.1101/2022.04.15.488448
Abstract: Sperm acrosomal membrane proteins, such as IZUMO1 and SPACA6, play an essential role in mammalian sperm–egg fusion. How their biosynthesis is regulated during spermiogenesis has largely remained unknown. Here, we show that the 1700029I15Rik knockout male mice are severely subfertile and their spermatozoa do not fuse with eggs. 1700029I15Rik encodes a type-II transmembrane protein that is expressed in early spermatids but not in mature spermatozoa. 1700029I15Rik is associated with proteins involved in N-glycosylation, disulfide isomerisation, and ER– Golgi trafficking, suggesting its involvement in nascent protein processing. 1700029I15Rik knockout testis has a normal level of sperm plasma membrane proteins, but decreased expression of multiple acrosomal membrane proteins. The knockout sperm exhibit elevated ubiquitinated proteins and upregulated ER-associated degradation strikingly, SPACA6 becomes undetectable. Our results support for a specific, 1700029I15Rik-mediated pathway in spermiogenesis for the assembly of acrosomal membrane proteins. In sexually reproducing species, life begins with the fusion between a sperm and an egg. Multiple sperm acrosomal membrane proteins have been reported indispensable for sperm–egg fusion in mammals, yet the mechanism underlying their biosynthesis remains unknown. The present study demonstrates the existence of a 1700029I15Rik-mediated pathway specifically coordinating the processing and assembly of acrosomal membrane proteins. It represents an intriguing paradigm where the biosynthesis of proteins destined for various subcellular compartments might be orchestrated in a spatiotemporal manner. Given 1700029I15Rik is highly conserved in human, our findings provide potential insights into the aetiology of idiopathic male infertility and the development of a novel contraceptive approach involving molecular interventions in the maturation of gamete fusion-required acrosomal proteins.
Publisher: Proceedings of the National Academy of Sciences
Date: 14-02-2023
Abstract: Sperm acrosomal membrane proteins, such as Izumo sperm–egg fusion 1 (IZUMO1) and sperm acrosome-associated 6 (SPACA6), play essential roles in mammalian gamete binding or fusion. How their biosynthesis is regulated during spermiogenesis has largely remained elusive. Here, we show that 1700029I15Rik knockout male mice are severely subfertile and their spermatozoa do not fuse with eggs. 1700029I15Rik is a type-II transmembrane protein expressed in early round spermatids but not in mature spermatozoa. It interacts with proteins involved in N -linked glycosylation, disulfide isomerization, and endoplasmic reticulum (ER)–Golgi trafficking, suggesting a potential role in nascent protein processing. The ablation of 1700029I15Rik destabilizes non-catalytic subunits of the oligosaccharyltransferase (OST) complex that are pivotal for N -glycosylation. The knockout testes exhibit normal expression of sperm plasma membrane proteins, but decreased abundance of multiple acrosomal membrane proteins involved in fertilization. The knockout sperm show upregulated chaperones related to ER-associated degradation (ERAD) and elevated protein ubiquitination strikingly, SPACA6 becomes undetectable. Our results support for a specific, 1700029I15Rik-mediated pathway underpinning the biosynthesis of acrosomal membrane proteins during spermiogenesis.
Publisher: Oxford University Press (OUP)
Date: 14-06-2019
Abstract: More than 1000 genes are predicted to be predominantly expressed in mouse testis, yet many of them remain unstudied in terms of their roles in spermatogenesis and sperm function and their essentiality in male reproduction. Since in idually indispensable factors can provide important implications for the diagnosis of genetically related idiopathic male infertility and may serve as candidate targets for the development of nonhormonal male contraceptives, our laboratories continuously analyze the functions of testis-enriched genes in vivo by generating knockout mouse lines using the CRISPR/Cas9 system. The dispensability of genes in male reproduction is easily determined by examining the fecundity of knockout males. During our large-scale screening of essential factors, we knocked out 30 genes that have a strong bias of expression in the testis and are mostly conserved in mammalian species including human. Fertility tests reveal that the mutant males exhibited normal fecundity, suggesting these genes are in idually dispensable for male reproduction. Since such functionally redundant genes are of diminished biological and clinical significance, we believe that it is crucial to disseminate this list of genes, along with their phenotypic information, to the scientific community to avoid unnecessary expenditure of time and research funds and duplication of efforts by other laboratories.
Publisher: Springer Science and Business Media LLC
Date: 07-04-2022
DOI: 10.1038/S42003-022-03289-W
Abstract: The process of sperm-egg fusion is critical for successful fertilization, yet the underlying mechanisms that regulate these steps have remained unclear in vertebrates. Here, we show that both mouse and zebrafish DCST1 and DCST2 are necessary in sperm to fertilize the egg, similar to their orthologs SPE-42 and SPE-49 in C. elegans and Sneaky in D. melanogaster . Mouse Dcst1 and Dcst2 single knockout (KO) sperm are able to undergo the acrosome reaction and show normal relocalization of IZUMO1, an essential factor for sperm-egg fusion, to the equatorial segment. While both single KO sperm can bind to the oolemma, they show the fusion defect, resulting that Dcst1 KO males become almost sterile and Dcst2 KO males become sterile. Similar to mice, zebrafish dcst1 KO males are subfertile and dcst2 and dcst1/2 double KO males are sterile. Zebrafish dcst1/2 KO sperm are motile and can approach the egg, but are defective in binding to the oolemma. Furthermore, we find that DCST1 and DCST2 interact with each other and are interdependent. These data demonstrate that DCST1/2 are essential for male fertility in two vertebrate species, highlighting their crucial role as conserved factors in fertilization.
Publisher: Oxford University Press (OUP)
Date: 03-2021
Publisher: Frontiers Media SA
Date: 12-01-2022
DOI: 10.3389/FCELL.2021.810118
Abstract: Fertilization occurs as the culmination of multi-step complex processes. First, mammalian spermatozoa undergo the acrosome reaction to become fusion-competent. Then, the acrosome-reacted spermatozoa penetrate the zona pellucida and adhere to and finally fuse with the egg plasma membrane. IZUMO1 is the first sperm protein proven to be essential for sperm-egg fusion in mammals, as Izumo1 knockout mouse spermatozoa adhere to but fail to fuse with the oolemma. However, the IZUMO1 function in other species remains largely unknown. Here, we generated Izumo1 knockout rats by CRISPR/Cas9 and found the male rats were infertile. Unlike in mice, Izumo1 knockout rat spermatozoa failed to bind to the oolemma. Further investigation revealed that the acrosome-intact sperm binding conceals a decreased number of the acrosome-reacted sperm bound to the oolemma in Izumo1 knockout mice. Of note, we could not see any apparent defects in the binding of the acrosome-reacted sperm to the oolemma in the mice lacking recently found fusion-indispensable genes, Fimp , Sof1 , Spaca6 , or Tmem95 . Collectively, our data suggest that IZUMO1 is required for the sperm-oolemma binding prior to fusion at least in rat.
Publisher: Proceedings of the National Academy of Sciences
Date: 11-05-2020
Abstract: The sperm−oocyte fusion step is important to transport the male genome into oocytes. So far, IZUMO1 and FIMP have been identified as fusion-related proteins in spermatozoa, but the molecular mechanisms underpinning sperm−oocyte fusion and all of the proteins required for this essential process remain unclear. In this study, using CRISPR-Cas9−mediated gene knockouts in mice, we discover that sperm proteins SOF1, TMEM95, and SPACA6 are required for sperm−oocyte fusion and male fertility. As these genes are conserved among mammals including human, they may explain not only the sperm−oocyte fusion process but also idiopathic male infertility and be unique targets for contraception.
Publisher: Proceedings of the National Academy of Sciences
Date: 15-04-2020
Abstract: As the human body is composed of 60 trillion cells that originate from a fertilized egg, sperm–oocyte fusion is the initial event of our life. Few sperm–oocyte fusion factors have been unveiled to date, and only IZUMO1 has been identified as a sperm-specific fusion-mediating protein. Here, we identified the testis-specific 4930451I11Rik gene important for male fertility, playing a role in sperm–oocyte fusion during fertilization. Based on its functional role, we renamed this gene fertilization influencing membrane protein ( Fimp ). We discovered a factor responsible for sperm–oocyte fusion in mammals, and this knowledge could be used to develop in vitro and in vivo infertility treatments as well as male contraceptives.
Publisher: Cold Spring Harbor Laboratory
Date: 06-2021
DOI: 10.1101/2021.06.01.446532
Abstract: Cilia and flagella are ancient structures that achieve controlled motor functions through the coordinated interaction of structures including dynein arms, radial spokes (RSs), microtubules, and the dynein regulatory complex (DRC). RSs facilitate the beating motion of these organelles by mediating signal transduction between dyneins and a central pair (CP) of singlet microtubules. RS complex isolation from Chlamydomonas axonemes enabled the detection of 23 different proteins (RSP1-23), with the roles of RSP13, RSP15, RSP18, RSP19, and RSP21 remained poorly understood. Herein, we show that Lrrc23 is an evolutionarily conserved testis-enriched gene encoding an RSP15 homolog in mice. Through immunoelectron microscopy, we demonstrate that LRRC23 localizes to the RS complex within murine sperm flagella. We further found that LRRC23 was able to interact with RSHP9 and RSPH3A/B. The knockout of Lrrc23 resulted in RS disorganization and impaired motility in murine spermatozoa, whereas the ciliary beating was unaffected by the loss of this protein. Spermatozoa lacking LRRC23 were unable to efficiently pass through the uterotubal junction and exhibited defective zona penetration. Together these data indicate that LRRC23 is a key regulator underpinning the integrity of RS complex within the flagella of mammalian spermatozoa, whereas it is dispensable in cilia.
Publisher: Cold Spring Harbor Laboratory
Date: 18-04-2021
DOI: 10.1101/2021.04.18.440256
Abstract: The process of sperm-egg fusion is critical for successful fertilization, yet the underlying mechanisms that regulate these steps have remained unclear in vertebrates. Here, we show that both mouse and zebrafish DCST1 and DCST2 are necessary in sperm to fertilize the egg, similar to their orthologs SPE-42 and SPE-49 in C. elegans and Sneaky in D. melanogaster . Mouse Dcst1 and Dcst2 single knockout (KO) spermatozoa are able to undergo the acrosome reaction and show normal relocalization of IZUMO1, an essential factor for sperm-egg fusion, to the equatorial segment. While both single KO spermatozoa can bind to the oolemma, they rarely fuse with oocytes, resulting in male sterility. Similar to mice, zebrafish dcst1 KO males are subfertile and dcst2 and dcst1/2 double KO males are sterile. Zebrafish dcst1/2 KO spermatozoa are motile and can approach the egg, but rarely bind to the oolemma. These data demonstrate that DCST1/2 are essential for male fertility in two vertebrate species, highlighting their crucial role as conserved factors in fertilization.
Publisher: The Company of Biologists
Date: 15-10-2021
DOI: 10.1242/JCS.259381
Abstract: Cilia and flagella are ancient structures that achieve controlled motor functions through the coordinated interaction based on microtubules and some attached projections. Radial spokes (RSs) facilitate the beating motion of these organelles by mediating signal transduction between dyneins and a central pair (CP) of singlet microtubules. RS complex isolation from Chlamydomonas axonemes enabled the detection of 23 radial spoke proteins (RSP1–RSP23), although the roles of some radial spoke proteins remain unknown. Recently, RSP15 has been reported to be bound to the stalk of RS2, but its homolog in mammals has not been identified. Herein, we show that Lrrc23 is an evolutionarily conserved testis-enriched gene encoding an RSP15 homolog in mice. We found that LRRC23 localizes to the RS complex within murine sperm flagella and interacts with RSPH3A and RSPH3B. The knockout of Lrrc23 resulted in male infertility due to RS disorganization and impaired motility in murine spermatozoa, whereas the ciliary beating was not significantly affected. These data indicate that LRRC23 is a key regulator that underpins the integrity of the RS complex within the flagella of mammalian spermatozoa, whereas it is dispensable in cilia. This article has an associated First Person interview with the first author of the paper.
No related grants have been discovered for Taichi NODA.