Activation of PKA/CREB Signaling is Involved in BMP9-Induced Osteogenic Differentiation of Mesenchymal Stem Cells.
OBJECTIVE
BMP9 is highly capable of promoting osteogenic differentiation of mesenchymal stem cells (MSCs) although the molecular mechanism involved is largely unknown. Here, we explored the detail role of PKA/CREB signaling in BMP9-induced osteogenic differentiation.


METHODS
Activation status of PKA/CREB signaling is assessed by nonradioactive assay and Western blot. Using PKA inhibitors and a dominant negative protein of CREB (A-CREB), we investigated the effect of PKA/CREB signaling on BMP9-induced osteogenic differentiation.


RESULTS
We found that BMP9 promotes PKA activity and enhances CREB phosphorylation in MSCs. BMP9 is shown to down-regulate protein kinase A inhibitor γ (PKIγ) expression. We demonstrated that PKA inhibitors suppress BMP9-induced early osteogenic marker alkaline phosphatase (ALP) activity in MSCs as well as late osteogenic markers osteopontin (OPN), osteocalcin (OCN) and matrix mineralization. We found that PKA inhibitor reduces BMP9-induced Runx2 activation and p38 phosphorylation in MSCs. Lastly, interference of CREB function by A-CREB decreased BMP9-induced osteogenic differentiation as well.


CONCLUSIONS
Our results revealed that BMP9 may activate PKA/CREB signaling in MSCs through suppression of PKIγ expression. It is noteworthy that inhibition of PKA/CREB signaling may impair BMP9-induced osteogenic differentiation of MSCs, implying that activation of PKA/CREB signaling is required for BMP9 osteoinductive activity.
Hongyu
H
Zhang
Li
L
Li
Qian
Q
Dong
Yufeng
Y
Wang
Qiaoling
Q
Feng
Xinying
X
Ou
Pengfei
P
Zhou
Tongchuan
T
He
Jinyong
J
Luo
D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D002460:Cell Line; D017362:Cyclic AMP Response Element-Binding Protein / Q000235:genetics / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D005786:Gene Expression Regulation / Q000187:drug effects; D055427:Growth Differentiation Factor 2 / Q000494:pharmacology*; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism*; D059630:Mesenchymal Stem Cells / Q000166:cytology / Q000187:drug effects*; D051379:Mice; D010012:Osteogenesis / Q000187:drug effects*; D010766:Phosphorylation / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects
C492004:Creb1 protein, mouse; D017362:Cyclic AMP Response Element-Binding Protein; D055427:Growth Differentiation Factor 2; D047908:Intracellular Signaling Peptides and Proteins; C515309:Pkig protein, mouse; D017868:Cyclic AMP-Dependent Protein Kinases