PCP protein Prickle 1 regulates Sertoli cell and testis function via cytoskeletal organization through the recruitment of multiple regulatory proteins.

Prickle 1, an ortholog found in Drosophila, was localized at the Sertoli cell-spermatid interface consistent with its role of supporting the Vangl2 planar cell polarity (PCP), is an integral membrane protein that creates the PCP protein complex of Vangl2 (Van Gogh-like 2)/Prickle1. Together with the asymmetrically localized transmembrane protein Frizzled (Fzd) and its unique adaptor proteins Disheveled (Dvl) and Inversin (Inv), Vangl2/Prickle1 and Fzd/Dvl/Inv are the two heterodimeric interacting PCP proteins between Sertoli cells and condensed spermatids to confer spermatid PCP across the plane of the seminiferous epithelium. Our initial intention was to examine if the distribution and expression of Prickle1 using a primary Sertoli cell in vitro model and Sprague-Dawley rats in vivo would mimic much of the earlier reported findings of Vangl2. Unexpectedly, these findings indicated that Prickle1 supported the PCP protein Vangl2, however, Prickle1 is also a multifunctional protein. First, Prickle1 knockdown (KD) by RNAi impeded Sertoli cell TJ-function by perturbing the distribution of the BTB-associated proteins at the cell-cell interface, through disruption of the microtubule (MT) and actin cytoskeletal organization including their respective polymerization (and/or bundling) capability. Second, these findings were reproduced using an in vivo model of RNAi by KD of Prickle 1 in the testis. Third, using Co-Immunoprecipitation (Co-IP), Prickle 1 was found to interact with a host of adaptor proteins crucial to support PCP including Dvl, but also regulatory cytoskeletal proteins of MT and actin networks, including RhoA, Arp3, Cdc42, ZO-1, and ß-catenin by IP-MS (Immunoprecipitation-Mass Spectrometry) using the String Protein Interaction Tool.