title: Glucosamine affects intracellular signalling through inhibition of mitogen-activated protein kinase phosphorylation in human chondrocytes.
abstract: The aim of this study was to determine the effects of glucosamine on matrix metalloprotease (MMP) production, on mitogen-activated protein kinase (MAPK) phosphorylation, and on activator protein (AP)-1 transcription factor activation in human chondrocytes. The human immortalized cell line lbpva55 and healthy human chondrocytes (obtained from healthy donors) were subjected to challenge with 10 ng/ml IL-1beta after pretreatment with 2.5 or 10 mmol/l glucosamine. MMP mRNA expression levels were evaluated using quantitative real-time PCR, and MMP protein production levels were evaluated in the culture supernatant using ELISA. MAPK phosphorylation was evaluated using Western blotting. AP-1 transcription factor activation was evaluated by measuring AP-1 DNA-binding activity. After IL-1beta stimulation, levels of MMP-1, MMP-3 and MMP-13 production were markedly increased. Treatment with 2.5 and 10 mmol/l glucosamine reduced expression of these metalloproteases. MMP expression is regulated by transcription factors such as the AP-1 complex, which is activated by phosphorylated MAPKs. IL-1beta stimulated phosphorylation of c-jun amino-terminal kinase, p38 MAPK and extracellular signal-regulated kinase-1/2. Glucosamine inhibited c-jun amino-terminal kinase and p38 phosphorylation, and consequently c-jun binding activity. These findings demonstrate, for the first time, that glucosamine inhibits IL-1beta-stimulated MMP production in human chondrocytes by affecting MAPK phosphorylation.
authors.affiliation: Department of Biochemical Sciences, Sapienza University of Roma, P.le Aldo Moro 5, 00185 Roma, Italy. anna.scottodabusco@uniroma1.it
authors.forename: Anna
authors.initials: A
authors.lastname: Scotto d'Abusco
authors.forename: Valentina
authors.initials: V
authors.lastname: Calamia
authors.forename: Claudia
authors.initials: C
authors.lastname: Cicione
authors.forename: Brunella
authors.initials: B
authors.lastname: Grigolo
authors.forename: Laura
authors.initials: L
authors.lastname: Politi
authors.forename: Roberto
authors.initials: R
authors.lastname: Scandurra
mesh_terms: D002461:Cell Line, Transformed; D002478:Cells, Cultured; D019902:Chondrocytes / Q000187:drug effects / Q000378:metabolism*; D005944:Glucosamine / Q000378:metabolism / Q000494:pharmacology*; D006801:Humans; D007424:Intracellular Fluid / Q000187:drug effects / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology*; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding / Q000187:drug effects / Q000502:physiology
chemical_list: D020928:Mitogen-Activated Protein Kinases; D005944:Glucosamine