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This Article Full Text Full Text (PDF) Supplemental Figures All Versions of this Article: 79/3/537    most recent biolreprod.108.067561v2 biolreprod.108.067561v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Google Scholar Articles by Nakamura, N. Articles by Eddy, E. M. PubMed PubMed Citation Articles by Nakamura, N. Articles by Eddy, E. M. Agricola Articles by Nakamura, N. Articles by Eddy, E. M.

Cleavage of Disulfide Bonds in Mouse Spermatogenic Cell-Specific Type 1 Hexokinase Isozyme Is Associated with Increased Hexokinase Activity and Initiation of Sperm Motility¹

Gamete Biology Section,³ Laboratory of Reproductive and Developmental Toxicology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709 Centro Andaluz de Biología del Desarrollo CABD-CSIC,⁴ Departamento de Fisiología, Anatomía y Biolgía Celular, Universidad Pablo de Olavide, 41013 Sevilla, Spain Department of Cell and Developmental Biology,⁵ School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599 Department of Bioenvironmental Medicine,⁶ Graduate School of Medicine, Chiba University, Chiba 260-8670, Japan

ABSTRACT

During epididymal transit, sperm acquire the ability to initiate rapid forward progressive motility on release into the female reproductive tract or physiological media. Glycolysis is the primary source of the ATP necessary for this motility in the mouse, and several novel glycolytic enzymes have been identified that are localized to the principal piece region of the flagellum. One of these is the spermatogenic cell-specific type 1 hexokinase isozyme (HK1S), the only member of the hexokinase enzyme family detected in sperm. Hexokinase activity was found to be lower in immotile sperm immediately after removal from the cauda epididymis (quiescent) than in sperm incubated in physiological medium for 5 min and showing rapid forward progressive motility (activated). However, incubating sperm in medium containing diamide, an inhibitor of disulfide bond reduction, resulted in lower motility and HK activity than in controls. HK1S was present in dimer and monomer forms in extracts of quiescent sperm but mainly as a monomer in motile sperm. A dimer-size band detected in quiescent sperm with phosphotyrosine antibody was not detected in activated sperm, and the monomer-size band was enhanced. In addition, the general protein oxido-reductase thioredoxin-1 was able to catalyze the in vitro conversion of HK1S dimers to the monomeric form. These results strongly suggest that cleavage of disulfide bonds in HK1S dimers contributes to the increases in HK activity and motility that occur when mouse sperm become activated.

disulfide bond reduction, epididymis, fibrous sheath, glycolysis, sperm, sperm activation, sperm capacitation, sperm maturation, sperm motility and transport

¹ Supported in part by the Intramural Research Program of the NIH, National Institute of Environmental Health Sciences and in part by a contract of the Spanish Ministry of Education and Science under the Ramón y Cajal Programme (A.M.-V.).

Correspondence: ²Edward M. Eddy, Gamete Biology Section, Laboratory of Reproductive and Developmental Toxicology, National Institutes of Health, National Institute of Environmental Health Sciences, 111 T.W. Alexander Drive, Research Triangle Park, North Carolina 27709. FAX: 919 541 3800; e-mail: eddy{at}niehs.nih.gov