Uroplakin 1a Interacts with Regucalcin and Proteasome Subunit Beta 1.

Uroplakins (UPKs) are specialized proteins that plan an important role in protecting the epithelium of the bladder from toxic waste. We recently demonstrated the expression pattern of UPKs in the male reproductive tract and their importance in sperm function in murine models. However, the exact mechanisms through which UPKs affect spermatogenesis are not reported. In this study, using yeast two-hybrid screening was conducted to determine the interaction partners of Uroplakin 1a (UPK1A). Y2H Gold yeast strain overexpressing UPK1A was mated with Y187 yeast strain overexpressing human testis cDNA library and the mutants were plated on SD agar plates containing selection media. Colonies that grew on SD/-Trp, SD/-Leu, SD/-His, and SD/-Ade plates were isolated and evaluated to identify the interacting partners of UPK1A. Regucalcin (RGN) and proteasome subunit beta 1 (PSMB1) were identified as potential interaction partners. Using HEK cells that overexpress UPK1A and RGN or PMSB1, the co-localization and interaction were estimated with high-resolution microscopy and Pearson's coefficient. In light of the fact that UPK1A knockout caused subfertility and that the role of RGN and PSMB1 in spermatogenesis is documented, an interaction between UPK1A and RGN or PSMB1 could be required for spermatogenesis.