SOX9 directly binds CREB as a novel synergism with the PKA pathway in BMP-2-induced osteochondrogenic differentiation.
SOX9 acts as a master transcription factor in osteochondrogenesis, and the phosphorylation by protein kinase A (PKA) has been shown to increase its DNA binding and transactivation activity. The PKA pathway is involved in the complex downstream signaling underlying the BMP-2-mediated osteochondrogenesis. This study therefore aimed at further analyzing the possible cross-talk between the SOX9 and the PKA regulation on the background of BMP-2 stimulation. It was first shown that the removal of the residues serine 64 and 211 of SOX9 diminished, but did not completely deplete, its stimulatory effect on the expression of both osteo- and chondrogenic markers. PKA activators and inhibitors increased and decreased the action of wildtype and mutated SOX9, respectively. Interestingly, the interplay of the SOX9 action with the PKA pathway was further shown to occur through direct physical association between SOX9 and CREB, a prototypical PKA downstream transcription factor. Moreover, the binding was shown to be an active biological event happening on BMP-2 stimulation. The C-terminal domain of SOX9 and amino acid residue serine at position 133 of CREB were identified to be involved in the interaction. The action of SOX9 was enhanced by overexpressing CREB. These results suggest that PKA signaling synergizes with SOX9 at the nuclear and cytoplasmic levels to promote BMP-2-induced osteochondrogenic differentiation.
Zhao
Li
L
Department of Orthopaedic Surgery, Center for Cancer Research and Cell Biology, School of Biomedical Sciences, Queen's University Belfast, Belfast, United Kingdom.
Li
Gang
G
Zhou
Guang-Qian
GQ
D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D055396:Bone Morphogenetic Protein 2 / Q000494:pharmacology*; D002454:Cell Differentiation / Q000187:drug effects*; D002460:Cell Line; D020219:Chondrogenesis / Q000187:drug effects*; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D006801:Humans; D051379:Mice; D010012:Osteogenesis / Q000187:drug effects*; D010766:Phosphorylation / Q000187:drug effects; D011485:Protein Binding / Q000187:drug effects; D055758:SOX9 Transcription Factor / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects
D015415:Biomarkers; D055396:Bone Morphogenetic Protein 2; C492004:Creb1 protein, mouse; D017362:Cyclic AMP Response Element-Binding Protein; D055758:SOX9 Transcription Factor; C527933:Sox9 protein, mouse; D017868:Cyclic AMP-Dependent Protein Kinases