title: Testicular hyperthermia induces Unfolded Protein Response signaling activation in spermatocyte.
abstract: The testes of most mammals are sensitive to temperature. To survive and adapt under conditions that promote endoplasmic reticulum (ER) stress such as heat shock, cells have a self-protective mechanism against ER stress that has been termed the "Unfolded Protein Response" (UPR). However, the cellular and molecular events underlying spermatogenesis with testicular hyperthermia involved in the UPR signaling pathway under ER stress remain poorly understood. In the present study, we verified that UPR signaling via phospho-eIF2α/ATF4/GADD34, p90ATF6, and phospho-IRE1α/XBP-1 is activated with testicular hyperthermia (43 °C, 15 min/day) and induced ER stress-mediated apoptosis associated with CHOP, phospho-JNK, and caspase-3 after repetitive periods of hyperthermia. Levels of phospho-eIF2α protein of mouse spermatocytes in the testis were rapidly increased by one cycle of testicular hyperthermia. ATF4/GADD34 and p90ATF6 expression gradually increased and decreased, respectively, with repetitive cycles of hyperthermia. Spliced XBP1 mRNA as a marker of IRE1 activity was increased after one, three cycles of hyperthermia and decreased by five cycles of hyperthermia. Although the levels of anti-apoptotic phospho-JNK (p54) were gradually decreased after three cycles of hyperthermia, CHOP expression was rapidly increased. After five cycles of testicular hyperthermia, the levels of cleaved caspase-3 and TUNEL-positive apoptotic spermatocytes cells were significantly increased. Our data demonstrated that testicular hyperthermia induces UPR signaling and repetitive cycles of hyperthermia lead to apoptosis of spermatocytes in mouse testis. These results suggest a link between the UPR signaling pathway and testicular hyperthermia.
authors.affiliation: College of Nature Sciences, Kyungpook National University, Daegu 702-701, Republic of Korea.
authors.forename: Jung-Hak
authors.initials: JH
authors.lastname: Kim
authors.forename: Sun-Ji
authors.initials: SJ
authors.lastname: Park
authors.forename: Tae-Shin
authors.initials: TS
authors.lastname: Kim
authors.forename: Hyo-Jin
authors.initials: HJ
authors.lastname: Park
authors.forename: Junghyung
authors.initials: J
authors.lastname: Park
authors.forename: Bo Kyung
authors.initials: BK
authors.lastname: Kim
authors.forename: Gyeong-Ryul
authors.initials: GR
authors.lastname: Kim
authors.forename: Jin-Man
authors.initials: JM
authors.lastname: Kim
authors.forename: Song Mei
authors.initials: SM
authors.lastname: Huang
authors.forename: Jung-Il
authors.initials: JI
authors.lastname: Chae
authors.forename: Choon-Keun
authors.initials: CK
authors.lastname: Park
authors.forename: Dong-Seok
authors.initials: DS
authors.lastname: Lee
mesh_terms: D051701:Activating Transcription Factor 4 / Q000378:metabolism; D051702:Activating Transcription Factor 6 / Q000378:metabolism; D017398:Alternative Splicing; D000818:Animals; D017209:Apoptosis / Q000235:genetics / Q000502:physiology; D015153:Blotting, Western; D053148:Caspase 3 / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000235:genetics / Q000378:metabolism; D059865:Endoplasmic Reticulum Stress / Q000235:genetics / Q000502:physiology; D004722:Endoribonucleases / Q000378:metabolism; D015852:Eukaryotic Initiation Factor-2 / Q000378:metabolism; D006358:Hot Temperature; D007150:Immunohistochemistry; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D054645:Protein Phosphatase 1 / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D000071701:Regulatory Factor X Transcription Factors; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology*; D013090:Spermatocytes / Q000378:metabolism*; D013737:Testis / Q000378:metabolism*; D051742:Transcription Factor CHOP / Q000378:metabolism; D014157:Transcription Factors / Q000235:genetics / Q000378:metabolism; D056811:Unfolded Protein Response / Q000235:genetics / Q000502:physiology*; D000071717:X-Box Binding Protein 1
chemical_list: D051702:Activating Transcription Factor 6; C081452:Atf4 protein, mouse; C497112:Atf6 protein, mouse; D004268:DNA-Binding Proteins; C497250:Ddit3 protein, mouse; D015852:Eukaryotic Initiation Factor-2; D000071701:Regulatory Factor X Transcription Factors; D014157:Transcription Factors; D000071717:X-Box Binding Protein 1; C000605544:Xbp1 protein, mouse; D051701:Activating Transcription Factor 4; D051742:Transcription Factor CHOP; C510185:Ern1 protein, mouse; D017346:Protein Serine-Threonine Kinases; D048031:JNK Mitogen-Activated Protein Kinases; D004722:Endoribonucleases; C513256:Ppp1r15a protein, mouse; D054645:Protein Phosphatase 1; D053148:Caspase 3