STUDIES OF PHOSPHOLIPASE A2 GENE EXPRESSION

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Cytosolic phospholipase A2(cPLA2) is an arachidonate specific phospholipase important in cellular production of eicosanoids. Cytokine activation of cPLA2 activity was studied in airway epithelial cells. It was found that the T-lymphocyte cytokine Interferon gamma-caused arachidonic acid release from airway epithelial cells. Western blot analysis revealed an increase in cPLA2 in epithelial cells treated with Interferon-gamma for 4-24 hours. Assays for steady state mRNA levels demonstrated an increase in cPLA2 mRNA levels over the same time frame and transcriptional analysis demonstrated an increase in the transcription rate of cPLA2 mRNA in response to Interferon stimulation. Similarly, TNF treatment of an airway epithelial cell line results in activation of arachidonic acid release. Western blots reveal increases in cPLA2 protein. Ribonuclease protection assay for cPLA2 mRNA reveals increases in steady state message for 4-24 hours. Transcriptional assay reveals an increase rate of transcription of cPLA2 mRNA in response to TNF treatment. Interleukin-6 is capable of activating PLA2 activity in some inflammatory cells. Another cytokine which utilizes gpl30 as a portion of its receptor is Leukemia Inhibitory Factor(LIF). Western blot of an airway epithelial cell line revealed LIF receptor protein. LIF treatment of these cells results in an increase in arachidonic acid release. Western blot analysis of cellular cPLA2 protein reveals an increase in protein in response to LIF treatment. Ribonuclease protection assay for cPLA2 steady state mRNA levels reveal an increase in cPLA2 message over 4-24 hours of treatment with LIF. Ongoing studies will assess the cytokine control of cPLA2 activity by gene expression and by post translational mechanisms. An understanding of the mechanisms of cytokine activation of cPLA2 may allow for new therapeutic diseases of the airways. One manuscript has been published and two manuscripts have been prepared.