ObjectiveTo investigate the expression and location of IQ motif-containing G (IQCG) in the human testis, compare its expression in normal-motility sperm with that in the sperm of asthenospermia patients, and explore its possible mechanisms and its correlation with fertility.

METHODSThe expression of the IQCG gene in the human testis was detected by RT-PCR and its location in the testis and sperm was determined by immunohistochemistry and immunofluorescence staining. Semen samples were collected from normal males, patients with asthenospermia, and fertile men that succeeded in artificial insemination with donor's sperm (AID), followed by analysis of the IQCG protein expression in different groups of samples by Western blot.

RESULTSImmunohistochemistry showed that IQCG was extensively expressed in the human testis, in the spermatocytes and spermatids, specifically in the sperm tail, weakly expressed or absent in the spermatogonial stem cells, and strongly expressed in the spermatogonial cells. The expression of IQCG was significantly lower in the asthenospermia patients than in the normal males (P= 0.041). Western blot manifested that IQCG was expressed in the semen of all the three groups of subjects, with statistically significant differences between the normal men and severe asthenospermia patients (P = 0.032) as well as between the fertile males and the severe asthenospermia group (P = 0.027) .

CONCLUSIONSIQCG may act on human sperm motility and its abnormal expression possibly reduces sperm motility and fertility. An insight into its action mechanisms may shed some new light on the etiology and treatment of asthenospermia.