Testis-specific fascin component FSCN3 is dispensable for mouse spermatogenesis and fertility.

BACKGROUND

Fascins belong to a family of actin-bundling proteins that are involved in a wide range of biological functions. FSCN3, a newly identified testis-specific actin-bundling protein, is specifically expressed in elongated spermatids. However, its in vivo function in mouse spermiogenesis remains unknown.

METHODS AND RESULTS

We generated Fscn3 knockout mice through CRISPR/Cas9 gene-editing technology. Fscn3 mice displayed normal testis morphology and testis to bodyweight ratio, and sperm concentrations did not differ significantly between Fscn3 and Fscn3 mice. Fertility assays consistently revealed that Fscn3 mice are completely fertile and their reproductive status does not differ from that of wild-type. Moreover, hematoxylin and eosin staining of the testis sections of Fscn3 mice detected various germ cells, ranging from spermatogonia to mature spermatozoa. Furthermore, the swimming velocity of the sperm of Fscn3 mice was comparable to that of their wild-type littermates. Both Fscn3 and Fscn3mice had normal sperm morphology, indicating that the disruption of Fscn3 does not affect sperm morphology. The analysis of meiotic prophase I progression demonstrated normal prophase-I phases (leptonema to diplonema) in both Fscn3 and Fscn3 mice, suggesting that Fscn3 is not essential for meiosis I.

CONCLUSION

Our study provides the first evidence that FSCN3 is a testis-specific actin-bundling protein that is not required for mouse spermatogenesis. Our results will help reproductive biologists focus their efforts on genes that are crucial for fertility and avoid research duplication.