Cytochrome c: Immunofluorescent Localization of the Testis-Specific Form

Goldberg, Erwin; Sberna, D; Wheat, Thomas E.; Urbanski, G. J.; Margoliash, E.

doi:10.1126/science.193188

Cited by 92 publications

(43 citation statements)

References 9 publications

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“…Mitochondrial proteins (51,71,72) show a typical granular staining around the nucleus in the spermatocytes in agreement with the observation that mitochondria are located very close to the outer nuclear membrane in these cells (73). On the other hand, the Golgi (the organelle from which the acrosome originates) proteins in a spermatocyte appear to have characteristic juxtanuclear localization, like in any other cell (56).…”

Section: Discussionsupporting

confidence: 86%

Novelty of the Pyruvate Metabolic Enzyme Dihydrolipoamide Dehydrogenasein Spermatozoa

Mitra¹,

Rangaraj

Shivaji

2005

Journal of Biological Chemistry

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Spermatozoa are cells distinctly different from other somatic cells of the body, capacitation being one of the unique phenomena manifested by this gamete. We have shown earlier that dihydrolipoamide dehydrogenase, a post-pyruvate metabolic enzyme, undergoes capacitation-dependent tyrosine phosphorylation, and the functioning of the enzyme is required for hyperactivation (enhanced motility) and acrosome reaction of hamster spermatozoa (Mitra, K., and Shivaji, S. (2004) Biol. Reprod. 70, 887-899). In this report we have investigated the localization of this mitochondrial enzyme in spermatozoa revealing non-canonical extra-mitochondrial localization of the enzyme in mammalian spermatozoa. In hamster spermatozoa, dihydrolipoamide dehydrogenase along with its host complex, the pyruvate dehydrogenase complex, are localized in the acrosome and in the principal piece of the sperm flagella. The localization of dihydrolipoamide dehydrogenase, however, appears to be in the mitochondria in the spermatocytes, but in spermatids it appears to show a juxtanuclear localization (like Golgi). The capacitation-dependent time course of tyrosine phosphorylation of dihydrolipoamide dehydrogenase appears to be different in the principal piece of the flagella and the acrosome in hamster spermatozoa. Activity assays of this bi-directional enzyme suggest a strong correlation between the tyrosine phosphorylation and the bi-directional enzyme activity. This is the first report of a direct correlation of the localization, tyrosine phosphorylation, and activity of the important metabolic enzyme, dihydrolipoamide dehydrogenase, implicating dual involvement and regulation of the enzyme during sperm capacitation.Spermatozoa, the haploid cells, are unique compared with other cells with respect to their morphology and functionality; needless to say the underlying signaling mechanisms in a functional spermatozoon are also unique. The metabolic pathways in a mature spermatozoon are compartmentalized (1-3), which probably enables them to survive in two different kinds of milieu, the male and the female reproductive tract. The residence time in the female reproductive tract is an obligatory event in the life cycle of a spermatozoon and has been termed "capacitation" (4, 5). During capacitation spermatozoa undergo multifaceted changes in aspects like metabolism, intracellular ion concentrations, plasma membrane fluidity, and thus membrane reorganization, intracellular pH, intracellular cAMP concentration, and generation of reactive oxygen species (6 -8). These cellular alterations during capacitation bring about three physiological changes: (a) hyperactivation (enhanced motility), (b) tyrosine phosphorylation in an array of proteins, and (c) acrosome reaction (release of the acrosomal contents); the first two events show a temporal correlation with capacitation, whereas acrosome reaction is taken to be the end point of capacitation (9).Protein tyrosine phosphorylation is considered to be a hallmark of sperm capacitation (10 -15), but only a few of thes...

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Section: Discussionsupporting

confidence: 86%

Novelty of the Pyruvate Metabolic Enzyme Dihydrolipoamide Dehydrogenasein Spermatozoa

Mitra¹,

Rangaraj

Shivaji

2005

Journal of Biological Chemistry

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“…In mice and rats, transcription of PDE11A3 uses the promoter of the testisspecific cytochrome-c gene, which is expressed only in spermatocytes and spermatids. 16,17 In humans, this gene is a nonfunctional pseudogene (HCP9). 7,18 The initiation methionine for the PDE11A3 protein is within the protein-coding region for cytochrome-c but is in a different reading frame.…”

Section: Discussionmentioning

confidence: 99%

3′,5′-Cyclic nucleotide phosphodiesterase 11A: localization in human tissues

2005

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“…The structure of the mammalian sperm mitochondrial capsule stabilizes the inner and outer mitochondrial membranes and so provides an intermembrane space that is, in effect, sperm specific. The genetic response to the milieu of this space has been expression of a sperm-specific isoform of cytochrome c, designated cytochrome c t to differentiate it from the somatic form, cytochrome c s (Goldberg et al, 1977;Hake and Hecht, 1993). The subunit VIb of cytochrome oxidase is the one subunit of this multiunit enzyme that accesses the intermembrane space; it too has a sperm-specific isoform (Hüttermann et al, 2003).…”

Section: Mitochondrial Activities: Oxygen As Friendmentioning

confidence: 99%

Mammalian sperm metabolism: oxygen and sugar, friend and foe

Storey¹

2008

Int. J. Dev. Biol.

296

260

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Mammalian spermatozoa expend energy, generated as intracellular ATP, largely on motility. If the sperm cell cannot swim by use of its flagellar motion, it cannot fertilize the egg. Studies of the means by which this energy is generated span a period of six decades. This review gives an overview of these studies, which demonstrate that both mitochondrial oxidative phosphorylation, for which oxygen is friend, and glycolysis, for which sugar is friend, can provide the energy, independent of one another. In mouse sperm, glycolysis appears to be the dominant pathway; in bull sperm, oxidative phosphorylation is the predominant pathway. In the case of bull sperm, the high activity of the glycolytic pathway would maintain the intracellular pH too low to allow sperm capacitation; here sugar is enemy. The cow's oviduct has very low glucose concentration, thus allowing capacitation to go forward. The choice of the pathway of energy generation in vivo is set by the conditions in the oviduct of the conspecific female. The phospholipids of the sperm plasma membrane have a high content of polyunsaturated fatty acids represented in their acyl moieties, rendering them highly susceptible to lipid peroxidation; in this case oxygen is enemy. But the susceptibility of the sperm membrane to lethal damage by lipid peroxidation allows the female oviduct to dispose of sperm that have overstayed their welcome, and so keep in balance sperm access to the egg and sperm removal once this has occurred.

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Cytochrome c: Immunofluorescent Localization of the Testis-Specific Form

Cited by 92 publications

References 9 publications

Novelty of the Pyruvate Metabolic Enzyme Dihydrolipoamide Dehydrogenasein Spermatozoa

Novelty of the Pyruvate Metabolic Enzyme Dihydrolipoamide Dehydrogenasein Spermatozoa

3′,5′-Cyclic nucleotide phosphodiesterase 11A: localization in human tissues

Mammalian sperm metabolism: oxygen and sugar, friend and foe

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