title: LPS-induced down-regulation of NO-sensitive guanylyl cyclase in astrocytes occurs by proteasomal degradation in clastosomes.
abstract: We previously showed that treatment with bacterial lipopolysaccharide (LPS) or pro-inflammatory cytokines decreases NO-sensitive guanylyl cyclase (GC(NO)) activity in astrocytes by decreasing the half-life of the obligate GC(NO) beta1 subunit in a NO-independent but transcription- and translation-dependent process. Here we show that LPS-induced beta1 degradation requires proteasome activity and is independent of NFkappaB activation or beta1 interaction with HSP90. Immunocytochemistry and confocal microscopy analysis revealed that LPS promotes colocalization of the predominantly soluble beta1 protein with ubiquitin and the 20S proteasome in nuclear aggregates that present characteristics of clastosomes, nuclear bodies involved in proteolysis via the ubiquitin-proteasome system. Proteasome and protein synthesis inhibitors prevented LPS-induced clastosome assembly and nuclear colocalization of beta1 with ubiquitin and 20S proteasome, strongly supporting a role for these transient nuclear structures in GC(NO) down-regulation during neuroinflammation.
authors: Institute of Biotechnology and Biomedicine V. Villar Palasí, Autonomous University of Barcelona, 08193 Bellaterra, Spain. mariaantonia.baltrons@uab.cat
authors: María Antonia
authors: MA
authors: Baltrons
authors: Paula
authors: P
authors: Pifarré
authors: María Teresa
authors: MT
authors: Berciano
authors: Miguel
authors: M
authors: Lafarga
authors: Agustina
authors: A
authors: García
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000187:drug effects* / Q000201:enzymology* / Q000648:ultrastructure; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology; D006152:Cyclic GMP / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D015536:Down-Regulation / Q000187:drug effects*; D004347:Drug Interactions; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects*; D006162:Guanylate Cyclase / Q000378:metabolism*; D008070:Lipopolysaccharides / Q000494:pharmacology*; D046529:Microscopy, Electron, Transmission / Q000379:methods; D009573:Nitrites / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D011863:Radioimmunoassay / Q000379:methods; D051381:Rats; D025801:Ubiquitin / Q000378:metabolism
chemical_list: D004791:Enzyme Inhibitors; D008070:Lipopolysaccharides; D009573:Nitrites; D025801:Ubiquitin; D046988:Proteasome Endopeptidase Complex; D006162:Guanylate Cyclase; D006152:Cyclic GMP