Protein kinase C-a coordinately regulates cytosolic phospholipase A2 activity and the expression of cyclooxygenase-2 through different mechanisms in mouse keratinocytes

Transgenic mice (K5-PKCa) in which the keratin 5 promoter directs the expression of protein kinase C-a (PKCa) to epider-mal keratinocytes display a 10-fold increase in PKCa protein in their epidermis and alterations in phorbol ester-induced cuta-neous inflammation [J Cell Science 1999;112:3497–3506]. In the current study, we have used these K5-PKCa mice to ex-amine the role of PKCa in keratinocyte phospholipid metabo-lism/eicosanoid production and cutaneous inflammation. Pri-mary keratinocytes from wild-type and transgenic mice were prelabeled in culture with [3H]arachidonic acid (AA) and subse-quently treated with TPA. Compared with wild-type keratino-cytes, K5-PKCa keratinocytes displayed a 2-fold increase in AA release. TPA treatment resulted in the phosphorylation of cPLA2. PKC inhibitors GF-109203X or H7, but not mitogen