title: Regulation of the G2/M phase of the cell cycle by sperm associated antigen 8 (SPAG8) protein.
abstract: Sperm associated antigen 8 (SPAG8), a testis-specific protein produced during male germ cell differentiation, was isolated from a human testis expression library using antibodies found in the serum obtained from an infertile woman. It was found to have a close functional relationship with microtubules. In this study, we generated a stably expressing SPAG8 CHO-K1 cell line. Immunofluorescence confocal microscopy showed that SPAG8 was concentrated at the microtubule-organizing center (MTOC) during prophase. As the cells progressed into metaphase, it co-localized with alpha-tubulin on the spindle. In anaphase, it was detected on both astral microtubules and mid-zone. Following cytokinesis, SPAG8 resumed its localization on the MTOC. Meanwhile, flow cytometry analysis found that SPAG8 prolonged the G2/M phase of CHO-K1 cells stably expressing SPAG8. Furthermore, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay showed that SPAG8 inhibited the proliferation of the stable cells. SPAG8 might be involved in the regulation of cell cycle by changing the phosphorylation level of Tyr15 on cdc2. These results suggest that SPAG8 might play a role in cell division during spermatogenesis.
authors: State Key Laboratory of Medical Molecular Biology, Institute of Basic Medical Sciences, Chinese Academy of Medical Sciences, Peking Union Medical College, Tsinghua University, Beijing, China.
authors: Rong
authors: R
authors: Li
authors: Xiao-Ling
authors: XL
authors: Tang
authors: Shi-Ying
authors: SY
authors: Miao
authors: Shu-Dong
authors: SD
authors: Zong
authors: Lin-Fang
authors: LF
authors: Wang
mesh_terms: D000818:Animals; D000954:Antigens, Surface / Q000378:metabolism*; D016203:CDC2 Protein Kinase / Q000378:metabolism; D016466:CHO Cells; D002453:Cell Cycle; D002455:Cell Division; D006224:Cricetinae; D003412:Cricetulus; D005260:Female; D016195:G2 Phase; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000378:metabolism*; D022101:Microtubule-Organizing Center / Q000378:metabolism; D008870:Microtubules / Q000378:metabolism; D010766:Phosphorylation; D013091:Spermatogenesis; D013997:Time Factors; D014404:Tubulin / Q000378:metabolism
chemical_list: D000954:Antigens, Surface; D008565:Membrane Proteins; C099014:SPAG8 protein, human; D014404:Tubulin; D016203:CDC2 Protein Kinase