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. ? ? ?

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
1R01GM082932-01
Application #
7349913
Study Section
Cellular, Molecular and Integrative Reproduction Study Section (CMIR)
Program Officer
Haynes, Susan R
Project Start
2007-09-10
Project End
2011-08-31
Budget Start
2007-09-10
Budget End
2008-08-31
Support Year
1
Fiscal Year
2007
Total Cost
$290,700
Indirect Cost
Name
Emory University
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
066469933
City
Atlanta
State
GA
Country
United States
Zip Code
30322
Ratliff, Miriam; Hill-Harfe, Katherine L; Gleason, Elizabeth J et al. (2018) MIB-1 Is Required for Spermatogenesis and Facilitates LIN-12 and GLP-1 Activity in Caenorhabditis elegans. Genetics 209:173-193
Nishimura, Hitoshi; Tajima, Tatsuya; Comstra, Heather Skye et al. (2015) The Immunoglobulin-like Gene spe-45 Acts during Fertilization in Caenorhabditis elegans like the Mouse Izumo1 Gene. Curr Biol 25:3225-31
Miao, Long; L'Hernault, Steven W (2014) Role of posttranslational modifications in C. elegans and ascaris spermatogenesis and sperm function. Adv Exp Med Biol 759:215-39
Tornieri, Karine; Zlatic, Stephanie A; Mullin, Ariana P et al. (2013) Vps33b pathogenic mutations preferentially affect VIPAS39/SPE-39-positive endosomes. Hum Mol Genet 22:5215-28
Zhao, Yanmei; Sun, Wei; Zhang, Pan et al. (2012) Nematode sperm maturation triggered by protease involves sperm-secreted serine protease inhibitor (Serpin). Proc Natl Acad Sci U S A 109:1542-7
Gleason, Elizabeth J; Hartley, Paul D; Henderson, Melissa et al. (2012) Developmental genetics of secretory vesicle acidification during Caenorhabditis elegans spermatogenesis. Genetics 191:477-91
Zlatic, Stephanie A; Tornieri, Karine; L'Hernault, Steven W et al. (2011) Clathrin-dependent mechanisms modulate the subcellular distribution of class C Vps/HOPS tether subunits in polarized and nonpolarized cells. Mol Biol Cell 22:1699-715
Nishimura, Hitoshi; L'Hernault, Steven W (2010) Spermatogenesis-defective (spe) mutants of the nematode Caenorhabditis elegans provide clues to solve the puzzle of male germline functions during reproduction. Dev Dyn 239:1502-14
Zhu, Guang-dan; Salazar, Gloria; Zlatic, Stephanie A et al. (2009) SPE-39 family proteins interact with the HOPS complex and function in lysosomal delivery. Mol Biol Cell 20:1223-40
L'Hernault, Steven W (2009) The genetics and cell biology of spermatogenesis in the nematode C. elegans. Mol Cell Endocrinol 306:59-65

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