Sox9/Sox6 and Sp1 are involved in the insulin-like growth factor-I-mediated upregulation of human type II collagen gene expression in articular chondrocytes.
Type II collagen is a marker of articular cartilage encoded by the COL2A1 gene. The nature of the trans factors involved in the upregulation of this gene by insulin-like growth factor-I (IGF-I) remains unclear. We found that IGF-I increased type II collagen synthesis by a transcriptional control mechanism involving a 715-bp region within the COL2A1 first-intron specific enhancer. The overproduction of L-Sox5/Sox6/Sox9 and Sp1 and decoy experiments targeting these factors demonstrated their action in concert in IGF-I trans-activation. These results were supported by the data obtained in knockdown experiments in which siRNA against Sox9/Sox6 and Sp1 prevented the IGF-I-induced increase in collagen II production. Indeed, each of these trans-activators increased the expression of others. IGF-I increased the binding of Sox9 and Sp1/Sp3 to their cis elements in the enhancer, and we provide the first evidence of Sox9 interaction with the promoter by chromatin immunoprecipitation. Interactions with COL2A1 were also observed for Sp1, p300/CBP, and Tip60. Finally, a physical interaction between Sox9, p300, Sp3, and Sp1 was detected. These data demonstrate the role of Sox9, Sp1/Sp3, and euchromatin-associated factors (p300, Tip60) in the IGF-I-induced upregulation of COL2A1, indicating possible use of this growth factor in articular cartilage engineering applications to promote repair in patients with degenerative diseases, such as osteoarthritis.
Laboratoire Matrice Extracellulaire et Pathologie, IFR ICORE 146, Université de Caen/Basse-Normandie, UFR de Médecine, CHU niveau 3, Avenue de la Côte de Nacre, 14032, Caen Cedex, France.
Emmanuelle
E
Renard
Benoît
B
Porée
Christos
C
Chadjichristos
Magdalini
M
Kypriotou
Laure
L
Maneix
Nicolas
N
Bigot
Florence
F
Legendre
David
D
Ollitrault
Benoît
B
De Crombrugghe
Frédéric
F
Malléin-Gérin
Safa
S
Moslemi
Magali
M
Demoor
Karim
K
Boumediene
Philippe
P
Galéra
D000818:Animals; D015153:Blotting, Western; D002358:Cartilage, Articular / Q000378:metabolism*; D002478:Cells, Cultured; D019902:Chondrocytes / Q000378:metabolism*; D024043:Collagen Type II / Q000235:genetics* / Q000378:metabolism; D005786:Gene Expression Regulation; D006801:Humans; D007136:Immunoglobulins / Q000235:genetics / Q000378:metabolism*; D007334:Insulin-Like Growth Factor I / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D011817:Rabbits; D055758:SOX9 Transcription Factor / Q000235:genetics / Q000378:metabolism*; D055755:SOXD Transcription Factors / Q000235:genetics / Q000378:metabolism*; D015854:Up-Regulation
C499177:COL2A1 protein, human; D024043:Collagen Type II; D007136:Immunoglobulins; C486270:SOX6 protein, human; D055758:SOX9 Transcription Factor; D055755:SOXD Transcription Factors; C090698:SP1 antigen; D007334:Insulin-Like Growth Factor I