Glucosamine and its N-acetyl-phenylalanine derivative prevent TNF-alpha-induced transcriptional activation in human chondrocytes.
OBJECTIVE
Glucosamine (GlcN) is used in the treatment of osteoarthritis as symptomatic slow-acting drug, but its mode of action is not completely known. We analyzed the influence of GlcN and its N-acetyl-phenylalanine derivative (NAPA) on mRNA transcription level of TNF-alpha-stimulated genes in cell culture.


METHODS
Human immortalized chondrocyte cell line lbpva55 was stimulated with TNF-alpha and treated with GlcN and NAPA. mRNA transcription level of several genes, identified by complementary DNA microarray (cDNA microarray), was validated by Quantitative Real-Time Polymerase Chain Reaction (Q-RT-PCR).


RESULTS
Several genes, whose mRNA level was increased by TNF-alpha treatment and significantly reduced by GlcN and NAPA in lbpva55 cells, were identified. These include cytokine receptors TNF-R1 and TNF-R2, their associated factor TRAF-6, signaling intermediates IGFB-6 and Rnd1, as well as cell cycle regulating proteins CUL-2 and G1S protein 1. Down- regulation of mRNA expression level of some of these genes is in accordance with inactivation of NF-kB transcription factor. Moreover, we found down-regulation of c-jun mRNA level, a component of AP-1 transcription factor.


CONCLUSIONS
Our study suggests that GlcN and NAPA interfere with activation of NF-kB and AP-1 transcription factors, which are responsible for the expression of genes involved in diverse biological processes, such as cell growth and death, inflammatory and stress responses, accounting for the beneficial effects of GlcN in osteoarthritis.
Scotto d'Abusco
A
A
Department of Biochemical Sciences, CNR, Sapienza University of Rome, Rome, Italy. anna.scottodabusco@uniromal.it
Cicione
C
C
Calamia
V
V
Negri
R
R
Giordano
C
C
Grigolo
B
B
Politi
L
L
Scandurra
R
R
D002460:Cell Line; D019902:Chondrocytes / Q000187:drug effects* / Q000502:physiology*; D044842:Cullin Proteins / Q000032:analysis; D015536:Down-Regulation; D015870:Gene Expression; D005944:Glucosamine / Q000494:pharmacology*; D006801:Humans; D016328:NF-kappa B / Q000032:analysis; D020411:Oligonucleotide Array Sequence Analysis; D010003:Osteoarthritis; D012333:RNA, Messenger / Q000032:analysis; D018124:Receptors, Tumor Necrosis Factor / Q000032:analysis; D047889:Receptors, Tumor Necrosis Factor, Type II / Q000032:analysis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D048029:TNF Receptor-Associated Factor 6 / Q000032:analysis; D015533:Transcriptional Activation / Q000187:drug effects*; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology*; D020741:rho GTP-Binding Proteins / Q000032:analysis
C105153:CUL2 protein, human; D044842:Cullin Proteins; D016328:NF-kappa B; D012333:RNA, Messenger; C491772:RND1 protein, human; D018124:Receptors, Tumor Necrosis Factor; D047889:Receptors, Tumor Necrosis Factor, Type II; D048029:TNF Receptor-Associated Factor 6; D014409:Tumor Necrosis Factor-alpha; D020741:rho GTP-Binding Proteins; D005944:Glucosamine