title: Lactate dehydrogenase C and energy metabolism in mouse sperm.
abstract: We demonstrated previously that disruption of the germ cell-specific lactate dehydrogenase C gene (Ldhc) led to male infertility due to defects in sperm function, including a rapid decline in sperm ATP levels, a decrease in progressive motility, and a failure to develop hyperactivated motility. We hypothesized that lack of LDHC disrupts glycolysis by feedback inhibition, either by causing a defect in renewal of the NAD(+) cofactor essential for activity of glyceraldehyde 3-phosphate dehydrogenase, sperm (GAPDHS), or an accumulation of pyruvate. To test these hypotheses, nuclear magnetic resonance analysis was used to follow the utilization of labeled substrates in real time. We found that in sperm lacking LDHC, glucose consumption was disrupted, but the NAD:NADH ratio and pyruvate levels were unchanged, and pyruvate was rapidly metabolized to lactate. Moreover, the metabolic disorder induced by treatment with the lactate dehydrogenase (LDH) inhibitor sodium oxamate was different from that caused by lack of LDHC. This supported our earlier conclusion that LDHA, an LDH isozyme present in the principal piece of the flagellum, is responsible for the residual LDH activity in sperm lacking LDHC, but suggested that LDHC has an additional role in the maintenance of energy metabolism in sperm. By coimmunoprecipitation coupled with mass spectrometry, we identified 27 proteins associated with LDHC. A majority of these proteins are implicated in ATP synthesis, utilization, transport, and/or sequestration. This led us to hypothesize that in addition to its role in glycolysis, LDHC is part of a complex involved in ATP homeostasis that is disrupted in sperm lacking LDHC.
authors.affiliation: Laboratories of Reproductive and Developmental Toxicology, National Institute of Environmental Health Sciences, National Institutes of Health, Research Triangle Park, North Carolina 27709-2233, USA.
authors.forename: Fanny
authors.initials: F
authors.lastname: Odet
authors.forename: Scott A
authors.initials: SA
authors.lastname: Gabel
authors.forename: Jason
authors.initials: J
authors.lastname: Williams
authors.forename: Robert E
authors.initials: RE
authors.lastname: London
authors.forename: Erwin
authors.initials: E
authors.lastname: Goldberg
authors.forename: Edward M
authors.initials: EM
authors.lastname: Eddy
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002247:Carbon Isotopes / Q000032:analysis; D005947:Glucose / Q000378:metabolism; D006019:Glycolysis; D047468:Immunoprecipitation; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism; D007770:L-Lactate Dehydrogenase / Q000037:antagonists & inhibitors / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D008297:Male; D013058:Mass Spectrometry; D053078:Membrane Potential, Mitochondrial; D051379:Mice; D018345:Mice, Knockout; D009243:NAD / Q000378:metabolism; D010072:Oxamic Acid; D019289:Pyruvic Acid / Q000378:metabolism; D013094:Spermatozoa / Q000378:metabolism*
chemical_list: D002247:Carbon Isotopes; D007527:Isoenzymes; D009243:NAD; D019289:Pyruvic Acid; D000255:Adenosine Triphosphate; D007770:L-Lactate Dehydrogenase; C409673:lactate dehydrogenase C4; D005947:Glucose; D010072:Oxamic Acid