title: Acrosome-specific gene AEP1: identification, characterization and roles in spermatogenesis.
abstract: Spermatogenesis is a tightly regulated process leading to the development of spermatozoa. To elucidate the molecular spermatogenic mechanisms, we identified an acrosome-specific gene AEP1 in spermatids, which is located in rat chromosome 17p14 with a transcript size of 3,091 bp encoding a signal peptide, zinc finger-like motif, coiled-coil region, several predicted glycosylation and phosphorylation sites. Northern blot and RT-PCR analyses revealed the restricted expression of AEP1 to the testis only. In postnatal rat testes, AEP1 mRNA became detectable from postnatal 25 dpp (round spermatids) and onwards. By using in situ hybridization (ISH) and flow cytometry-fluorescent ISH, only the haploid spermatids yielded the positive AEP1 signal. Immunohistochemistry showed that AEP1 was expressed in the acrosomal cap of late-staged germ cells in rat testis, and co-localized with the acrosomal marker, peanut agglutinin. The spatial expression of AEP1 immunoreactivity in testis was conserved among diverse mammalian species (rat, pig, monkey, human). To further study its roles in spermatogenesis, we showed AEP1 and beta-actin was associated together in complex by co-immunoprecipitation in adult germ cells and by immunofluorescence assay in isolated spermatozoon. In human testes diagnosed with hypospermatogenesis, lower expression of AEP1 was observed, whereas there was no detectable signal in undescended testes. In short, AEP1 is an evolutionary-conserved acrosome-specific gene and likely functions in acrosome-cap formation.
authors.affiliation: Department of Surgery, The University of Hong Kong, Jockey Club Clinical Research Center, 21 Sassoon Road, Pokfulam, Hong Kong. jmluk@hkucc.hku.hk
authors.forename: John M
authors.initials: JM
authors.lastname: Luk
authors.forename: Nikki P Y
authors.initials: NP
authors.lastname: Lee
authors.forename: Cathy K
authors.initials: CK
authors.lastname: Shum
authors.forename: Brian Y
authors.initials: BY
authors.lastname: Lam
authors.forename: Annie F M
authors.initials: AF
authors.lastname: Siu
authors.forename: Chi-Ming
authors.initials: CM
authors.lastname: Che
authors.forename: Po-Chor
authors.initials: PC
authors.lastname: Tam
authors.forename: Annie N Y
authors.initials: AN
authors.lastname: Cheung
authors.forename: Z M
authors.initials: ZM
authors.lastname: Yang
authors.forename: Yi-Nan
authors.initials: YN
authors.lastname: Lin
authors.forename: Martin M
authors.initials: MM
authors.lastname: Matzuk
authors.forename: Kai-Fai
authors.initials: KF
authors.lastname: Lee
authors.forename: William S B
authors.initials: WS
authors.lastname: Yeung
mesh_terms: D000177:Acrosome / Q000502:physiology*; D000328:Adult; D000595:Amino Acid Sequence; D000818:Animals; D002478:Cells, Cultured; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D051379:Mice; D008969:Molecular Sequence Data; D017434:Protein Structure, Tertiary; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D016415:Sequence Alignment; D013091:Spermatogenesis / Q000502:physiology*; D013094:Spermatozoa / Q000166:cytology / Q000378:metabolism; D013737:Testis / Q000166:cytology / Q000502:physiology; D014018:Tissue Distribution; D016335:Zinc Fingers
chemical_list: D011506:Proteins; C516716:SPATA31A7 protein, human