Effects of the PYK2 Gene on Monocyte LPS-dependent Signalling

The results of these studies indicate that activation of THP-1 cells by treatment with LPS is altered in PYK2-transfected cells. The effect of PYK2 on the regulation of IL-1beta and TNF-alpha cytokine secretion appeared to be dependent on the amount of PYK2 expressed in PYK2-GFP transfected cells. The level of PYK2 was 2-fold greater at the RNA level than in PYK2-RFP transfected cells. In THP-1 cells expressing the higher levels of PYK2-GFP, the level of cytokines secreted in response to LPS was lower than in controls while cells expressing lower levels of PYK2-RFP cytokine secretion was augmented. Treatment of the cells with LPS also caused MAP kinase activation as well as FAK and PYK2 phosphorylation when compared to untreated THP-1 controls treated with LPS. Additionally, stable expression of a truncated form of PYK2 decreased cytokine production dramatically but strongly promoted MAP kinase activation in cells treated with LPS. Stable expression in THP-1 cells of GFP- and RFP-tagged PYK2 and PYK2 mutants also demonstrated that both full-length PYK2 and dominant negative PYK2-693 localize to the cytoplasm.