title: Lipopolysaccharide stimulates differential expression of myristoylated protein kinase C substrates in murine microglia.
abstract: Microglia rapidly respond to lipoplysaccharide (LPS) by transformation from resting to active states and secretion of several neuro- and immuno-regulators including tumour necrosis factor alpha (TNF-alpha), interleukin 1 beta (IL-1 beta), and interleukin 6 (IL-6). With longer LPS treatment, microglia are converted to reactive or phagocytic states with characteristics similar to macrophages in inflammation and injury processes. We have investigated LPS-mediated changes in two myristoylated substrates of protein kinase C (PKC): MARCKS (myristoylated alaninerich C kinase substrate) and MRP (MARCKS-related protein). Within 6 hours of addition, LPS induced a twofold increase in [3H]myristoylated and immunoreactive MARCKS protein and a sevenfold increase in MRP. The differential effect of LPS on expression of MRP vs. MARCKS was even more dramatic at the level of transcription: S1 nuclease protection assays revealed a 40-fold increase in MRP mRNA levels (maximum at 4-6 hours), whereas a threefold increase was observed for MARCKS. TNF alpha and colony-stimulating factor 1 (CSF-1), two cytokines which are induced by LPS, did not reproduce the observed effect of LPS on MARCKS and MRP gene transcription. CSF-1 also induced differential transcription of MRP, but of lower magnitude (threefold) and more sustained than by LPS. Accordingly, these two substrates for PKC are differentially up-regulated by LPS, apparently independent of TNF alpha or CSF-1.
authors.affiliation: Atlantic Research Centre, Department of Pediatrics, Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: S D
authors.initials: SD
authors.lastname: Rosé
authors.forename: D M
authors.initials: DM
authors.lastname: Byers
authors.forename: S C
authors.initials: SC
authors.lastname: Morash
authors.forename: S
authors.initials: S
authors.lastname: Fedoroff
authors.forename: H W
authors.initials: HW
authors.lastname: Cook
mesh_terms: D000818:Animals; D001427:Bacterial Toxins / Q000494:pharmacology*; D015153:Blotting, Western; D002148:Calmodulin-Binding Proteins; D002478:Cells, Cultured; D004591:Electrophoresis, Polyacrylamide Gel; D004768:Enterotoxins / Q000494:pharmacology*; D029968:Escherichia coli Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008070:Lipopolysaccharides / Q000494:pharmacology*; D016173:Macrophage Colony-Stimulating Factor / Q000096:biosynthesis / Q000494:pharmacology; D008565:Membrane Proteins; D051379:Mice; D008809:Mice, Inbred C3H; D008840:Microfilament Proteins; D017628:Microglia / Q000187:drug effects / Q000201:enzymology / Q000378:metabolism*; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; D014176:Protein Biosynthesis; D011493:Protein Kinase C / Q000096:biosynthesis / Q000378:metabolism*; D012333:RNA, Messenger / Q000096:biosynthesis; D015719:Single-Strand Specific DNA and RNA Endonucleases / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D001427:Bacterial Toxins; D002148:Calmodulin-Binding Proteins; D004768:Enterotoxins; D029968:Escherichia coli Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008070:Lipopolysaccharides; C000619711:Marcks protein, mouse; C512945:Marcksl1 protein, mouse; D008565:Membrane Proteins; D008840:Microfilament Proteins; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D000076250:Myristoylated Alanine-Rich C Kinase Substrate; D016173:Macrophage Colony-Stimulating Factor; C027538:heat-labile enterotoxin, E coli; D011493:Protein Kinase C; D015719:Single-Strand Specific DNA and RNA Endonucleases