Genomes and Genes
Secretory Vesicle Function During Spermatogenesis & Fertilization in C. elegans
Principal Investigator: STEVEN W L'HERNAULT
Abstract: DESCRIPTION (provided by applicant): The long-term goal of this work is to determine the molecular and cellular mechanisms required for sperm-egg fusion during fertilization. This proposal addresses how a sperm secretory vesicle (acrosome) forms properly so that it can fuse with and create a fertilization-competent cell surface on the spermatozoon. Sperm secretory vesicles acquire an acidic internal pH during their maturation due to vacuolar (V-) ATPase activity, and this occurs in many animals, including humans. However, the mechanisms that regulate V-ATPase activity in sperm secretory vesicles are not understood, mostly because a spermatogenesis system suitable for its analysis had not been identified. Our preliminary data show that Caenorhabditis elegans spermatogenesis is ideally suited for analyzing the V-ATPase role and regulation during biogenesis and function of sperm secretory vesicles. In particular, mutations in the spe-5 gene alter a V-ATPase subunit that is spermatogenesis-specific, so acidification of sperm secretory vesicles can be studied in the absence of somatic V-ATPase defects, which are usually lethal. The spe-16 gene encodes a spermatogenesis-specific ubiquitin E3 ligase and how it participates in developmentally controlled acidification of sperm secretory vesicles will be determined. The focused objective of this proposal is to determine how the spe-5 and spe-16 encoded proteins cooperate to regulate internal pH in sperm secretory vesicles and what happens when this regulation is disrupted. We use three specific aims to test the overall hypothesis that the internal pH of sperm secretory vesicles must fall in order for this organelle to fuse with the plasma membrane. Specific aim #1 is to identify the role of the V-ATPase during sperm secretory vesicle maturation. Specific aim #2 is to identify how absence of V-ATPase function affects sperm motility and function during fertilization. Specific aim #3 is to identify why secretory vesicles fail to acidify in spe-16 loss of function mutant sperm. The unusual nature of the spe-16 mutant phenotype ensures it utilizes a previously undescribed way of regulating an animal V-ATPase. Ubiquitin is conjugated to proteins in normal human sperm, including those in the acrosome, and ubiquitination defects occur in infertile men;the role of ubiquitination is not understood in either case. Defects in ubiquitin biology are associated with various cancers, neurodegenerative diseases and many other disease processes. In addition to its role during spermatogenesis, V-ATPase function is defective in diseases that include renal Fanconi syndrome and the bone diseases, infantile ostepetrosis and osteoporosis. This proposal is focused on how sperm develop the ability to fertilize an egg. This is a problem of significant public health impact because ~15% of couples desiring children are infertile and many cases are due to defective sperm. The processes we study, in addition to functioning in sperm, also play a role in proper kidney function and bone formation.
Funding Period: ----------------2007 - ---------------2011-
more information: NIH RePORT
- SPE-39 family proteins interact with the HOPS complex and function in lysosomal deliveryGuang dan Zhu
Graduate Program in Biochemistry, Cell, and Developmental Biology, Departments of Biology and Cell Biology, and Department of Neurology, Center for Neurodegenerative Disease, Emory University, Atlanta, GA 30322
Mol Biol Cell 20:1223-40. 2009..elegans spermatogenesis is an experimental system useful for identifying conserved regulators of metazoan lysosomal biogenesis...
- The genetics and cell biology of spermatogenesis in the nematode C. elegansSTEVEN W L'HERNAULT
Department of Biology, Emory University, Atlanta, GA 30322, USA
Mol Cell Endocrinol 306:59-65. 2009..In this article, I will review spermatogenesis, how mutants are made and what has been learned about the identified genes and their roles during development and fertilization...
- The CIL-1 PI 5-phosphatase localizes TRP Polycystins to cilia and activates sperm in C. elegansYoung Kyung Bae
Department of Genetics, Rutgers University, The State University of New Jersey, Piscataway, NJ 08854, USA
Curr Biol 19:1599-607. 2009..TRPP complex ciliary localization and sensory function are evolutionarily conserved. A genetic screen for C. elegans mutants with PKD-2 ciliary localization (Cil) defects led to the isolation of a mutation in the cil-1 gene...
- Spermatogenesis-defective (spe) mutants of the nematode Caenorhabditis elegans provide clues to solve the puzzle of male germline functions during reproductionHitoshi Nishimura
Department of Biology, Emory University, Atlanta, Georgia 30322, USA
Dev Dyn 239:1502-14. 2010..Moreover, several spe genes are orthologs of mammalian genes, suggesting that the reproductive processes of the C. elegans and the mammalian male germlines might share common pathways at the molecular level...
- Clathrin-dependent mechanisms modulate the subcellular distribution of class C Vps/HOPS tether subunits in polarized and nonpolarized cellsStephanie A Zlatic
Department of Cell Biology, Emory University, Atlanta, GA 30322, USA
Mol Biol Cell 22:1699-715. 2011..We propose that vesicular (AP-3) and nonvesicular (Hrs) clathrin mechanisms segregate class C Vps/HOPS tethers to organelles and domains of mammalian cells bearing complex architectures...
- Nematode sperm maturation triggered by protease involves sperm-secreted serine protease inhibitor (Serpin)Yanmei Zhao
Laboratory of Noncoding RNA, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China
Proc Natl Acad Sci U S A 109:1542-7. 2012....
- Developmental genetics of secretory vesicle acidification during Caenorhabditis elegans spermatogenesisElizabeth J Gleason
Department of Biology, Graduate Programs, Emory University, Atlanta, Georgia 30322, USA
Genetics 191:477-91. 2012..Others have shown that the X chromosome is transcriptionally silent in the male germline, so expression of the autosomally located spe-5 gene ensures that a V-ATPase B subunit is present during spermatogenesis...