Modulation of cytosolic phospholipase A2

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Jiang, Yan Jenny
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Peroxisome proliferator activated receptors (PPARs) belong to the superfamily of nuclear hormone receptors that heterodimerize with the retinoid X receptor and regulate the transcription of several genes responsible for lipid metabolism and adipocyte differentiation. Three subtypes of PPAR have been found so far, including PPAR-_, -_ and -[delta] (or B). PPAR_ is predominantly expressed in tissues with high catabolic rates for fatty acids and peroxisomal metabolism. PPAR_ plays a pivotal role in the control of metabolic function in the adipocyte. PPAR[delta] is ubiquitously expressed, but the function is less known. In this study, we hypothesize that the catabolism of phospholipids by the cPLA2 is regulated via the activation of PPAR pathways at the transcriptional level. The objective of our study is to elucidate the role of PPARs in the regulation of cPLA 2 in mammalian cells. Since cyclooxygenase-1/2 (COX-1 and -2) are key enzymes for conversion of AA to eicosanoids, and cPLA2 and COX-2 are functionally coupled in eicosanoids biosynthesis, we also examined the gene expression of COX-1 and COX-2. Using the human preadipocyte SW872 cell line as a model, the modulation of arachidonic acid release by PPAR activators was examined. The modification of CPLA2 activity by lyso-PC at the post-translational level was investigated using rat heart myoblastic H9c2 cells as a model. (Abstract shortened by UMI.)