Qiang LIU, Huai Yu WANG, Xi-Jun HE

J Vet Med Sci. 2019 Sep 20. doi: 10.1292/jvms.19-0157

Abstract

Immunoproteasome (i-proteasome) has both immune and non-immune functions and plays important roles in controlling infections and combating illnesses. Our previous studies suggest that interferon (IFN)-γ induces the expression of three immune-specific catalytic subunits of the 20S proteasome that can replace their constitutive homologues to form the i-proteasome in immune cells, such as porcine alveolar macrophages (AMs) in vitro. However, i-proteasome levels and their modulation in non-immune cells such as the epithelial cells in pigs remain unknown. Here, we investigated the expression of i-proteasomes in non-immune cells (porcine kidney (PK)-15 cells) to determine i-proteasome modulation upon stimulation of PK-15 cells with IFN-γ and tumor necrosis factor (TNF)-α in vitro. The expression of i-proteasome subunits in PK-15 cells were regulated by IFN-γ and TNF-α. Remarkably, we found that the combination treatment of IFN-γ and TNF-α increased the expression of i-proteasome subunits LMP2, LMP7, and MECL-1 in PK-15 cells at transcriptional levels, but decreased their expression at the translational level, in comparison to their expression levels induced by individual cytokine treatments. These results provide critical insight into i-proteasome modulation in porcine non-immune cells, contributes further to our understanding of i-proteasome function in tissue pathogenesis and the development of antiviral adaptive immune responses against intracellular infections.

KEYWORDS:

epithelial cell; immunoproteasome; interferon-γ; pig; tumor necrosis factor-α