Involvement of nuclear factor of activated T cells in granulocyte–macrophage colony‐stimulating factor production in canine keratinocytes stimulated with a cysteine protease

Abstract

A previous study demonstrated that the cysteine protease of Dermatophagoides farinae induced production of granulocyte-macrophage colony-stimulating factor (GM-CSF) in a canine epidermal keratinocyte progenitor cell line (CPEK); however, the molecular mechanism has not been elucidated. Given that the transcription of GM-CSF mRNA in human lymphocytes is mainly regulated by the nuclear factor of activated T cells (NFAT), it is hypothesized that NFAT also contributes to GM-CSF production in canine keratinocytes stimulated with a cysteine protease. Nuclear translocation of NFAT was evaluated in CPEK cells in the absence or presence of the cysteine protease papain. We also investigated whether blockade of NFAT could inhibit GM-CSF production. Papain-induced nuclear translocation of NFAT, producing GM-CSF, was partly inhibited by ciclosporin. The results suggest that GM-CSF production mediated by the cysteine protease is regulated not only by NFAT but also by unknown signalling pathways in canine keratinocytes.