Expression of Apg-1, a member of the Hsp110 family, in the human testis and sperm

• Published in: International journal of urology 2001-06, Vol.8 (6), p.308-314
• Main Authors: Nonoguchi, Kohsuke, Tokuchi, Hiromu, Okuno, Hiroshi, Watanabe, Hirohiko, Egawa, Haruto, Saito, Kaoru, Ogawa, Osamu, Fujita, Jun
• Format: Article
• Language: English
• Subjects: Adult; Animals; Apg-1; Blotting, Western; chaperone; gene expression; Gene Expression - physiology; Heat Stress Disorders - pathology; Heat Stress Disorders - physiopathology; Heat-Shock Proteins - analysis; Heat-Shock Proteins - genetics; Heat-Shock Response - physiology; HSP110 Heat-Shock Proteins; HSP70 Heat-Shock Proteins - genetics; Humans; Male; Mice; Mice, Inbred C57BL; Oligospermia - pathology; Oligospermia - physiopathology; RNA, Messenger - analysis; Sertoli Cells - chemistry; Sertoli Cells - pathology; Sertoli Cells - physiology; Spermatids - cytology; Spermatids - physiology; spermatogenesis; Spermatogenesis - physiology; Spermatozoa - chemistry; Spermatozoa - cytology; Spermatozoa - physiology; stress; Testicular Neoplasms; Testis - chemistry; Testis - cytology; Testis - physiology; Tumor Cells, Cultured
• ISSN: 0919-8172; 1442-2042
• DOI: 10.1046/j.1442-2042.2001.00304.x

Background: Apg‐1 encodes a heat shock protein belonging to the Hsp110 family and is inducible by a 32°C to 39°C heat shock in somatic cells. In mouse testicular germ cells Apg‐1 mRNA is constitutively expressed depending on the developmental stage. As human Apg‐1 has recently been identified, the expression of Apg‐1 in the human testis and sperm was investigated. Methods: Expression and heat‐inducibility of Apg‐1 in the human testicular germ cell tumor cell line, NEC8, was analyzed. Using an antimouse Apg‐1 antibody, expression of Apg‐1 in the human testis and sperm was examined by western blotting after confirmation of the specificity of the antibody. The cells expressing Apg‐1 in the testis were further determined by immunohistochemistry. Results: Slight induction of Apg‐1 mRNA was detected in NEC8 cells after 32°C to 39°C temperature shift. In the human testis, the antibody specifically recognized Apg‐1, which was absent in the testis without germ cells (Sertoli‐cell‐only syndrome) or arrested at spermatogonia. Spermatocytes and spermatids, but not testicular somatic cells, were positively stained with the anti‐Apg‐1 antibody. By western blot analysis, Apg‐1 was detected in the preparation enriched for sperm from normal volunteers and infertile patients, but not from azoospermia patients. Conclusion: Apg‐1 is developmentally expressed in human testicular germ cells and sperm, suggesting its role in spermatogenesis and fertilization. Identification of substrates for Apg‐1 chaperone activity will help elucidate its function.