Role of protein kinase C zeta in lipopolysaccharide-mediated nuclear factor kappa B aactivation [i.e. activation] and aactivity [i.e. activity] in kidney epithelial cells

Abstract

NF-kappaB is a critical transcription factor that mediates cellular responses to invading pathogens. In the kidney, NF-kappaB's most important targets are the cytokines and chemokines, which regulate the scale of the inflammatory response by recruiting and facilitating immunocyte activity in the kidney, especially polymorphonuclear leukocytes. For induction of these genes, NF-kappaB must be translocated from the cytoplasm to the nuclear compartment, bind nuclear kappaB consensus elements and induce RNA polymerase loading at these sites.In this work we show that in kidney proximal tubule cells, PKCzeta acts upstream of multiple phases of NF-kappaB activation, and is a determinant of the profile of cytokines induced in response to LPS. We show that PKCzeta interacts with the IKK complex directly and that inhibition of PKCzetas catalytic activity with either pharmacologic inhibitors or overexpression of a dominant negative PKCzeta blocks IKK activity and subsequent NF-kappaB DNA binding. We also show that PKCzeta regulates NF-kappaB transactivation not only through direct phosphorylation of serine 311 on p65, but also through a novel regulatory mechanism associated with p300 activation. The culmination of PKCzeta activity is a shift in the expression of NF-kappaB driven genes away from the proinflammatory genes, TNFalpha and Cox-2, to the inflammatory resolution genes IL-6 and A20.