OBJECTIVETo investigate the expression of the Chk1 gene in human sperm and its clinical significance.

METHODSWe collected 80 semen samples and divided them into 4 groups of equal number: normal, oligospermia, asthenozoospermia and oligoasthenozoospermia. The Chk1 expression and its relative level were detected by Western blot and RT-PCR, sperm DNA damage and gradient changes assessed by DNA ladder analysis, and sperm apoptosis determined by Annexin V/PI double staining in each group.

RESULTSThe Chk1 gene was expressed in all the four groups, but with significant differences (P < 0.01); the relative levels of CHK1 protein were similar to those of Chk1 mRNA in the normal, oligospermia, asthenozoospermia and oligoasthenozoospermia groups, which were 1.00 +/- 0.22, 0.76 +/- 0.10, 0.45 +/- 0.08 and 0.37 +/- 0.07, respectively. DNA ladder analysis showed a marked DNA ladder in the asthenozoospermia and oligoasthenozoospermia groups. Sperm apoptosis was markedly increased in the oligospermia, asthenozoospermia, oligoasthenozoospermia and 100% graded sperm groups ([ 8.3 +/- 0.60]%, [11.6 +/- 0.92]%, [12.5 +/- 1.43]% and [17.0 +/- 1.98]%), as compared with the normal group ([7.6 +/- 0.34]%) (P < 0.05).

CONCLUSIONChk1 is expressed in human sperm, but differently in different semen quality groups. And its expression is correlated with sperm DNA damage and apoptosis; its reduction may lead to declined sperm repair and increased sperm apoptosis and thus affect semen quality.