The immunophilins are an important group of regulatory molecules in the immune system. FKBP5, expressed throughout mammals and in fish and birds, functions in both physiological and pathogenic pathways, including innate immunity and steroid-based diseases. In this study, we cloned the first porcine FKBP5 from Rongchang pig by the rapid amplification of cDNA ends technique. The full-length cDNA is 4097 bp, with an open reading frame of 1371 bp that codes for a 457-aa protein. Western blotting detected the porcine FKBP5 protein at highest levels in thymus, followed by spleen and lung. Immunohistochemistry detected the porcine FKBP5 protein in lymphocytes and granulocytes of the blood, and flow cytometry identified greater expression in unactivated (vs. activated) T lymphocytes. Finally, the expression level of porcine FKBP5 in the granulocytes was found to decline significantly from the time of birth to one-year-old. These collective data suggest that the newly identified porcine FKBP5 may function in activation of T cells in pig and in innate immunity in the newborn pig in particular.
Keywords: FKBP5; Pig; T cell activation; immunophilin; innate immunity.