UBPy/MSJ-1 system during male germ cell progression in the frog, Rana esculenta

mUBPy (mouse ubiquitin specific processing protease) is a de-ubiquitinating enzyme expressed in mouse testis and brain. In testis, it interacts with the DnaJ protein MSJ-1 (mouse sperm cell specific DnaJ first homologue), a molecular chaperone expressed in spermatids and spermatozoa. Since MSJ-1 is conserved among vertebrates, to demonstrate an evolutionarily conserved function of UBPy/MSJ-1 system, we assayed mUBPy presence in the anuran amphibian, the frog, Rana esculenta, during the annual sexual cycle. By Western blot we have detected a specific signal of 126 kDa in testis and isolated spermatozoa. During the annual sexual cycle, the signal gradually increases as soon as spermatogenesis resumes after the winter stasis. Using immunocytochemistry, we have localized the protein in spermatids and spermatozoa. In conclusion, UBPy/MSJ-1 system is available in R. esculenta testis suggesting a conserved fundamental function in spermatogenesis and sperm formation.