title: Effects of acid sphingomyelinase deficiency on male germ cell development and programmed cell death.
abstract: Deficiency of acid sphingomyelinase (ASM), an enzyme responsible for producing a pro-apoptotic second messenger ceramide, has previously been shown to promote the survival of fetal mouse oocytes in vivo and to protect oocytes from chemotherapy-induced apoptosis in vitro. Here we investigated the effects of ASM deficiency on testicular germ cell development and on the ability of germ cells to undergo apoptosis. At the age of 20 weeks, ASM knock-out (ASMKO) sperm concentrations were comparable with wild-type (WT) sperm concentrations, whereas sperm motility was seriously affected. ASMKO testes contained significantly elevated levels of sphingomyelin at the age of 8 weeks as detected by high-performance, thin-layer chromatography. Electron microscopy revealed that the testes started to accumulate pathological vesicles in Sertoli cells and in the interstitium at the age of 21 days. Irradiation of WT and ASMKO mice did not elevate intratesticular ceramide levels at 16 h after irradiation. In situ end labeling of apoptotic cells also showed a similar degree of cell death in both groups. After a 21-day recovery period, the numbers of primary spermatocytes and spermatogonia at G2 as well as spermatids were essentially the same in the WT and ASMKO testes, as detected by flow cytometry. In serum-free cultures both ASMKO and WT germ cells showed a significant increase in the level of ceramide, as well as massive apoptosis. In conclusion, ASM is required for maintenance of normal sphingomyelin levels in the testis and for normal sperm motility, but not for testicular ceramide production or for the ability of the germ cells to undergo apoptosis.
authors.affiliation: Program for Developmental and Reproductive Biology, Biomedicum Helsinki and Hospital for Children and Adolescents, University of Helsinki, FIN-00029 HUS, Helsinki, Finland. marjut.otala@hus.fi
authors.forename: Marjut
authors.initials: M
authors.lastname: Otala
authors.forename: Markku O
authors.initials: MO
authors.lastname: Pentikäinen
authors.forename: Tiina
authors.initials: T
authors.lastname: Matikainen
authors.forename: Laura
authors.initials: L
authors.lastname: Suomalainen
authors.forename: Jukka K
authors.initials: JK
authors.lastname: Hakala
authors.forename: Gloria I
authors.initials: GI
authors.lastname: Perez
authors.forename: Mikko
authors.initials: M
authors.lastname: Tenhunen
authors.forename: Krista
authors.initials: K
authors.lastname: Erkkilä
authors.forename: Petri
authors.initials: P
authors.lastname: Kovanen
authors.forename: Martti
authors.initials: M
authors.lastname: Parvinen
authors.forename: Leo
authors.initials: L
authors.lastname: Dunkel
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000502:physiology*; D016923:Cell Death / Q000502:physiology / Q000528:radiation effects; D002478:Cells, Cultured; D002518:Ceramides / Q000378:metabolism; D016895:Culture Media, Serum-Free; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D012708:Sertoli Cells / Q000473:pathology; D013081:Sperm Motility / Q000502:physiology; D013094:Spermatozoa / Q000166:cytology* / Q000502:physiology* / Q000528:radiation effects; D013108:Sphingomyelin Phosphodiesterase / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism; D013109:Sphingomyelins / Q000378:metabolism; D013737:Testis / Q000166:cytology / Q000254:growth & development / Q000528:radiation effects
chemical_list: D002518:Ceramides; D016895:Culture Media, Serum-Free; D013109:Sphingomyelins; D013108:Sphingomyelin Phosphodiesterase