Expression patterns of HENMT1 and PIWIL1 in human testis: implications for transposon expression.

This study aimed to define the expression patterns of HENMT1 and PIWI proteins in human testis and investigate their association with transposon expression, infertility sub-type or development of testicular germ cell tumours (TGCTs). Testis biopsies showing normal spermatogenesis were used to identify normal localisation patterns of HENMT1 and PIWIL1 by immunolocalisation and RT-PCR after laser microdissection. 222 testis biopsies representing normal spermatogenesis, hypospermatogenesis, spermatogenic arrests, Sertoli cell-only (SCO) tumours and TGCTs were analysed by RT-qPCR for expression of and Additionally, -overexpressing TCam2 seminoma cell lines were analysed for the same parameters by RT-qPCR. We found that and are coexpressed in pachytene spermatocytes and spermatids. Expression of , and was mainly dependent on germ cell content but low levels of expression were also detected in some SCO samples. Levels of , and expression were low in TGCT. Samples with and expression showed significantly ( < 0.05) lower transposon expression compared to samples without expression in the same histological group. HENMT1-overexpressing TCam2 cells showed lower expression than empty vector-transfected control lines. Our findings support that the transposon-regulating function of the piRNA pathway found in the mouse is conserved in adult human testis. HENMT1 and PIWI proteins are expressed in a germ-cell-specific manner and required for transposon control.