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This Article Full Text Full Text (PDF) All Versions of this Article: 290/6/E1145    most recent 00142.2005v1 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 Citing Articles Citing Articles via ISI Web of Science (1) Citing Articles via Google Scholar Google Scholar Articles by Erkkila, K. Articles by Dunkel, L. Search for Related Content PubMed PubMed Citation Articles by Erkkila, K. Articles by Dunkel, L.

Regulation of human male germ cell death by modulators of ATP production

¹Program for Developmental and Reproductive Biology, Biomedicum Helsinki, and Hospital for Children and Adolescents, ³Helsinki Bioenergetics Group, Institute of Biotechnology, University of Helsinki; ⁴Department of Urology, Helsinki University Hospital, Helsinki; ⁵Department of Pediatrics, Kuopio University Hospital, University of Kuopio, Kuopio, Finland; and ²Division of Endocrinology, Department of Medicine, Harbor-University of California Los Angeles Medical Center and Los Angeles Biomedical Research Institute, David Geffen Medical School at the University of California Los Angeles, Torrance, California

Submitted 30 March 2005 ; accepted in final form 4 January 2006

The understanding of testicular physiology, pathology, and male fertility issues requires knowledge of male germ cell death and energy production. Here, we induced human male germ cell apoptosis (detected by Southern blot analysis of DNA fragmentation, TUNEL, activation of caspases-3 and -9, and electron microscopy) by incubating seminiferous tubule segments under hormone- and serum-free conditions. Inhibitors of complexes I to IV of mitochondrial respiration, exposure to anoxia, and inhibition of F₀F₁-ATPase (with oligomycin) decreased the ATP levels (analyzed by HPLC) and suppressed apoptosis at 4 h. Uncoupler 2,4-dinitrophenol (DNP) and oligomycin combination also suppressed death at 4 h, as did the DNP alone. Inhibition of glycolysis by 2-deoxyglucose neither suppressed nor further induced apoptosis nor altered the antiapoptotic effects of the mitochondrial inhibitors. Furthermore, Fas system activation did not modify the effects of mitochondrial modulators. After 24 h, delayed male germ cell apoptosis was observed despite the presence of the mitochondrial inhibitors. We conclude that the mitochondrial ATP production machinery plays an important role in regulating in vitro-induced primary pathways of human male germ apoptosis. The ATP synthesized by the F₀F₁-ATPase seems to be the crucial death regulator, rather than any of the complexes (I-IV) alone, the functional electron transport chain, or the membrane potential. We also conclude that there seem to be secondary pathways of human testicular cell apoptosis that do not require mitochondrial ATP production. The present study emphasizes the role of the main catabolic pathways in the complex network of regulating events of male germ cell life and death.

testis; spermatogenesis; apoptosis; mitochondria; oxidative phosphorylation