Kinesin KIFC1 is essential for meiotic recombination and male fertility in mice

Purpose: KIFC1 functions a crucial role in the formation and structural maintenance of mitotic and meiotic spindles. Its loss is linked to reduced fertility and the production of polyploid offspring. This study determines the effects of KIFC1 deficiency on spermatogenesis and germ cell differentiation in mice, particularly during meiosis prophase I and metaphase. Methods: C57BL/6J mice with global KIFC1 knockout were generated using the CRISPR/Cas9 system. Histological and fluorescence imaging analyses revealed KIFC1's involvement in meiotic recombination. To further explore the effects of KIFC1 loss on fertility, RNA sequencing, liquid chromatography-mass spectrometry, and single-cell RNA sequencing were employed. Results: KIFC1 deficiency resulted in a significant reduction of germ cells in seminiferous tubules, decreased testicular volume, and disrupted meiosis. In severely affected mice, spermatocytes arrested at the zygotene-like stage. Although KIFC1 loss does not impact the initiation of DNA double-strand breaks, it is essential for homologous chromosome pairing and crossover formation. KIFC1-null spermatocytes exhibited delayed DNA recombination, leading to abnormal chromosome alignment and polyploid gametes. Conclusions: This study highlights KIFC1's critical role in homologous recombination and chromosome segregation during male germ cell meiosis. Multi-omics analyses reveal how KIFC1 deficiency affects spermatocyte differentiation and spermatogenesis, with additional evidence suggesting impairment of mitochondrial function.