PCP Protein Inversin Regulates Testis Function Through Changes in Cytoskeletal Organization of Actin and Microtubules

Inversin is an integrated component of the Frizzled (Fzd)/Dishevelled (Dvl)/Diversin planar cell polarity (PCP) complex that is known to work in concert with the Van Gogh-like protein (eg, Vangl2)/Prickle PCP complex to support tissue and organ development including the brain, kidney, pancreas, and others. These PCP protein complexes are also recently shown to confer developing haploid spermatid PCP to support spermatogenesis in adult rat testes. However, with the exception of Dvl3 and Vangl2, other PCP proteins have not been investigated in the testis. Herein, we used the technique of RNA interference (RNAi) to examine the role of inversin (Invs) in Sertoli cell (SC) and testis function by corresponding studies in vitro and in vivo. When inversin was silenced by RNAi using specific small interfering RNA duplexes by transfecting primary cultures of SCs in vitro or testes in vivo, it was shown that inversin knockdown (KD) perturbed the SC tight junction–barrier function in vitro and in vivo using corresponding physiological and integrity assays. More important, inversin exerted its regulatory effects through changes in the organization of the actin and microtubule cytoskeletons, including reducing the ability of their polymerization. These changes, in turn, induced defects in spermatogenesis by loss of spermatid polarity, disruptive distribution of blood-testis barrier–associated proteins at the SC-cell interface, appearance of multinucleated round spermatids, and defects in the release of sperm at spermiation.