TKTL1: a new candidate gene in nonobstructive azoospermia

The genetic background of the non-obstructive azoospermia (NOA) remains poorly known. However, recent studies employing next generation sequencing techniques were able to uncover some NOA causative genes, among which was the TKTL1 gene. In this article we aim to understand the function of the TKTL1 gene in human spermatogenesis by inducing its overexpression in human testicular primary cells (hTPc), which we verified in male gonad tissue samples collected from NOA patients by uncovering the genes cluster regulated by TKTL1. Successful overexpression of the TKTL1 gene was achieved in hTP cells, the TKTL1 gene expression level was significantly higher in modified cells compared to both control groups (p<0.01). Using RNA-seq, we selected 20 genes which expression levels significantly differed in the modified hTP cells overexpressing TKTL1 gene in comparison to both controls. Male gonad tissue samples collected from NOA patients harbouring a mutation in the TKTL1 gene showed a significant downregulation (p<0.05) in HERC5, CSF3, HES1 and HSPA1B genes, compared to both controls, which was in accordance with the results obtained for hTPc cells, as the overexpression of the TKTL1 gene correlated with an increased expression level of the named genes compared to control groups.