Expression of Apg-1, a member of the Hsp110 family, in the human testis and sperm.
BACKGROUND
Apg-1 encodes a heat shock protein belonging to the Hsp110 family and is inducible by a 32 degrees C to 39 degrees 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 degrees C to 39 degrees 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.


CONCLUSIONS
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.
Nonoguchi
K
K
Department of Clinical Molecular Biology, Faculty of Medicine, Kyoto University, Kyoto, Japan.
Tokuchi
H
H
Okuno
H
H
Watanabe
H
H
Egawa
H
H
Saito
K
K
Ogawa
O
O
Fujita
J
J
D000328:Adult; D000818:Animals; D015153:Blotting, Western; D015870:Gene Expression / Q000502:physiology; D050957:HSP110 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins / Q000235:genetics; D018882:Heat Stress Disorders / Q000473:pathology / Q000503:physiopathology; D006360:Heat-Shock Proteins / Q000032:analysis / Q000235:genetics*; D018869:Heat-Shock Response / Q000502:physiology; D006801:Humans; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009845:Oligospermia / Q000473:pathology / Q000503:physiopathology; D012333:RNA, Messenger / Q000032:analysis; D012708:Sertoli Cells / Q000737:chemistry / Q000473:pathology / Q000502:physiology; D013087:Spermatids / Q000166:cytology / Q000502:physiology; D013091:Spermatogenesis / Q000502:physiology; D013094:Spermatozoa / Q000737:chemistry / Q000166:cytology / Q000502:physiology*; D013736:Testicular Neoplasms; D013737:Testis / Q000737:chemistry / Q000166:cytology / Q000502:physiology*; D014407:Tumor Cells, Cultured
D050957:HSP110 Heat-Shock Proteins; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D012333:RNA, Messenger; C490979:HSPA4L protein, human; C099678:Hspa4l protein, mouse