title: Mitogen-activated protein kinase signaling in male germ cell apoptosis in the rat.
abstract: Programmed germ cell death is critical for functional spermatogenesis. Increased germ cell apoptosis can be triggered by various regulatory stimuli, including testicular hyperthermia or deprivation of gonadotropins and intratesticular testosterone. We have previously shown the involvement of the mitogen-activated protein kinase (MAPK) 14 in apoptotic signaling of male germ cells across species after hormone deprivation. This study investigates the role of MAPK14 in germ cell apoptosis in rats triggered by testicular hyperthermia. The contributions of the MAPK1/3 and the MAPK8 to male germ cell death were also examined after this intervention. We show that 1) testicular hyperthermia results in induction of both MAPK1/3 and MAPK14 but not MAPK8; 2) inhibition of MAPK1/3 has no effect on the incidence of heat-induced germ cell apoptosis, suggesting that MAPK1/3 signaling may be dispensable for heat-induced male germ cell apoptosis; and 3) activation of MAPK14 and BCL2 phosphorylation are critical for heat-induced male germ cell apoptosis in rats. Thus, unlike the hormone deprivation model, heat stress through activation of the MAPK14 signaling promotes germ cell apoptosis by provoking BCL2 phosphorylation, leading to its inactivation and the subsequent activation of the mitochondria-dependent death pathway. These novel findings point to a critical role of MAPK14 in stage- and cell-specific activation of male germ cell apoptosis triggered by hormone deprivation or heat stress.
authors.affiliation: Division of Endocrinology, Department of Medicine, Harbor-UCLA Medical Center, David Geffen School of Medicine at UCLA and Los Angeles Biomedical Research Institute, Torrance, California 90509, USA.
authors.forename: Yue
authors.initials: Y
authors.lastname: Jia
authors.forename: Jesse
authors.initials: J
authors.lastname: Castellanos
authors.forename: Christina
authors.initials: C
authors.lastname: Wang
authors.forename: Indrani
authors.initials: I
authors.lastname: Sinha-Hikim
authors.forename: Yanhe
authors.initials: Y
authors.lastname: Lue
authors.forename: Ronald S
authors.initials: RS
authors.lastname: Swerdloff
authors.forename: Amiya P
authors.initials: AP
authors.lastname: Sinha-Hikim
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005334:Fever / Q000378:metabolism; D007093:Imidazoles / Q000494:pharmacology; D020935:MAP Kinase Signaling System / Q000502:physiology*; D008297:Male; D048308:Mitogen-Activated Protein Kinase 14 / Q000378:metabolism; D048055:Mitogen-Activated Protein Kinase 8 / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism / Q000502:physiology; D008954:Models, Biological; D010766:Phosphorylation; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000378:metabolism / Q000502:physiology; D011725:Pyridines / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013094:Spermatozoa / Q000201:enzymology / Q000502:physiology*; D013737:Testis / Q000201:enzymology / Q000378:metabolism / Q000473:pathology
chemical_list: D004791:Enzyme Inhibitors; D007093:Imidazoles; D019253:Proto-Oncogene Proteins c-bcl-2; D011725:Pyridines; D048308:Mitogen-Activated Protein Kinase 14; D048055:Mitogen-Activated Protein Kinase 8; D020928:Mitogen-Activated Protein Kinases; C093642:SB 203580