T-Complex Protein 1 Subunit Zeta-2 (Cct6b) Deficiency Induces Murine Teratospermia

Background. The CCT complex is an important mediator of microtubule assembly and intracellular protein folding. Owing to its high expression in spermatids, CCT knockdown can disrupt spermatogenesis. In the present report, we therefore evaluated the in vivo functionality of the testis-specific CCT complex component CCT6B using a murine knockout model system.Methods. A CRISPR/Cas9 approach was used to generate Cct6b(-/-) mice, after which candidate gene expression in these animals was evaluated via qPCR and Western blotting. Testicular and epididymal phenotypes were assessed through histological and immunofluorescent staining assays, while a computer-assisted sperm analyzer was employed to assess semen quality.Results. Cct6b(-/-) mice were successfully generated, and exhibited no differences in development, fertility, appearance, testis weight, or sperm counts relative to control littermates. In addition, no differences in spermatogenesis were detected when comparing Cct6b(+/+) and Cct6b(-/-) testes. However, when progressive motility was analyzed, the ratio of normal sperm was significantly decreased in Cct6b(-/-) male mice, with nuclear base bending being the primary detected abnormality. In addition, slight decreases in Cct4 and Cct7 expression were detected.Conclusion. These data indicated that CCT6B is an important regulator of murine spermatogenesis, with the loss of this protein resulting in CCT complex dysfunction, providing a foundation for further studies.