tailieunhanh - Báo cáo khoa học: Complex transcriptional and translational regulation of iPLA2c resulting in multiple gene products containing dual competing sites for mitochondrial or peroxisomal localization

Membrane-associated calcium-independent phospholipase A2c(iPLA2c) contains four potential in-frame methionine start sites (Mancuso, . Jenkins, . & Gross, . (2000)J. Biol. , 9937–9945), but the mechanisms regulating the types, amount and subcellular localization of iPLA2c in cells are incompletely understood. We now: (a) demonstrate the dramatic transcriptional repression of mRNAsynthesis encoding iPLA2cby a nucleotide sequence nested in the coding sequence itself; (b) localize the site of transcriptional repression to the most 5¢ sequence encoding the iPLA2choloprotein; (c) identify the presence of nuclear proteinconstituentswhichbind to the repressor regionbygel shift analysis;. | Eur. J. Biochem. 271 4709-4724 2004 FEBS 2004 doi Complex transcriptional and translational regulation of iPLA2c resulting in multiple gene products containing dual competing sites for mitochondrial or peroxisomal localization David J. Mancuso1 2 Christopher M. Jenkins1 2 Harold F. Sims1 2 Joshua M. Cohen1 2 Jingyue Yang1 2 and Richard W. Gross1 2 3 4 1 Division of Bioorganic Chemistry and Molecular Pharmacology and Departments of 2Medicine 3 Chemistry and 4 Molecular Biology and Pharmacology Washington University School of Medicine St. Louis MO USA Membrane-associated calcium-independent phospholipase A2c iPLA2y contains four potential in-frame methionine start sites Mancuso . Jenkins . Gross . 2000 J. Biol. Chem. 275 9937-9945 but the mechanisms regulating the types amount and subcellular localization of iPLA27 in cells are incompletely understood. We now a demonstrate the dramatic transcriptional repression of mRNA synthesis encoding iPLA2c by a nucleotide sequence nested in the coding sequence itself b localize the site of transcriptional repression to the most 5 sequence encoding the iPLA2c holoprotein c identify the presence of nuclear protein constituents which bind to the repressor region by gel shift analysis d demonstrate the translational regulation of distinct iPLA2c isoforms e identify multiple novel exons promoters and alternative splice variants of human iPLA2y f document the presence of dual-competing subcellular localization signals in discrete isoforms of iPLA2y and g demonstrate the functional integrity of an N-terminal mitochondrial localization signal by fluorescence imaging and the presence of iPLA2c in the mitochondrial compartment of rat myocardium. The intricacy of the regulatory mechanisms of ÍPLA2Y biosynthesis in rat myocardium is underscored by the identification of seven distinct protein products that utilize multiple mechanisms transcription translation and proteolysis to produce discrete .