Background:
Cdc2-like kinases (CLKs) are conserved regulators of alternative splicing through phosphorylation of serine/arginine-rich splicing factors. CLK3 exhibits highly restricted expression within meiotic and post-meiotic germ cells and is enriched in heat-sensitive germ cell populations, suggesting specialised functions in spermatogenesis. However, the physiological role of CLK3 in male fertility remains unknown.
Methods:
To investigate the role of CLK3 in spermatogenesis, we generated Clk3 knockout mice and characterised reproductive phenotypes through fertility testing, sperm analysis and histological assessment. Pharmacological inhibition studies were also performed to examine the effects of acute CLK inhibition on male reproductive function. Transcriptomic analyses were undertaken to identify molecular pathways disrupted following loss of CLK3.
Results:
Loss of CLK3 resulted in severe impairment of male fertility, accompanied by marked reductions in sperm quality and defects in spermatogenic progression. Pharmacological inhibition of CLK activity similarly disrupted male reproductive parameters, supporting an essential role for CLK signalling in germ cell development. Transcriptomic analyses identified widespread alterations in gene expression and RNA processing pathways, consistent with a role for CLK3 in maintaining germ cell transcriptional and post-transcriptional regulatory programs.
Conclusions:
These findings identify CLK3 as an essential regulator of mammalian spermatogenesis and male fertility. The restricted expression profile of CLK3 and the infertility phenotype associated with its disruption suggest that CLK3-dependent signalling pathways may represent novel mechanisms regulating germ cell development and potential targets for non-hormonal male contraception.