Pharmacological Inhibition of Protein Kinase G1 Enhances Bone Formation by Human Skeletal Stem Cells Through Activation of RhoA-Akt Signaling

TY - JOUR

T1 - Pharmacological Inhibition of Protein Kinase G1 Enhances Bone Formation by Human Skeletal Stem Cells Through Activation of RhoA-Akt Signaling

AU - Kermani, Abbas Jafari

AU - Siersbaek, Majken S

AU - Chen, Li

AU - Qanie, Diyako

AU - Zaher, Walid

AU - Abdallah, Basem M

AU - Kassem, Moustapha

N1 - © 2015 AlphaMed Press.

PY - 2015/7/1

Y1 - 2015/7/1

N2 - Development of novel approaches to enhance bone regeneration is needed for efficient treatment of bone defects. Protein kinases play a key role in regulation of intracellular signal transduction pathways, and pharmacological targeting of protein kinases has led to development of novel treatments for several malignant and nonmalignant conditions. We screened a library of kinase inhibitors to identify small molecules that enhance bone formation by human skeletal (stromal or mesenchymal) stem cells (hMSC). We identified H-8 (known to inhibit protein kinases A, C, and G) as a potent enhancer of ex vivo osteoblast (OB) differentiation of hMSC, in a stage- and cell type-specific manner, without affecting adipogenesis or osteoclastogenesis. Furthermore, we showed that systemic administration of H-8 enhances in vivo bone formation by hMSC, using a preclinical ectopic bone formation model in mice. Using functional screening of known H-8 targets, we demonstrated that inhibition of protein kinase G1 (PRKG1) and consequent activation of RhoA-Akt signaling is the main mechanism through which H-8 enhances osteogenesis. Our studies revealed PRKG1 as a novel negative regulator of OB differentiation and suggest that pharmacological inhibition of PRKG1 in hMSC implanted at the site of bone defect can enhance bone regeneration.

AB - Development of novel approaches to enhance bone regeneration is needed for efficient treatment of bone defects. Protein kinases play a key role in regulation of intracellular signal transduction pathways, and pharmacological targeting of protein kinases has led to development of novel treatments for several malignant and nonmalignant conditions. We screened a library of kinase inhibitors to identify small molecules that enhance bone formation by human skeletal (stromal or mesenchymal) stem cells (hMSC). We identified H-8 (known to inhibit protein kinases A, C, and G) as a potent enhancer of ex vivo osteoblast (OB) differentiation of hMSC, in a stage- and cell type-specific manner, without affecting adipogenesis or osteoclastogenesis. Furthermore, we showed that systemic administration of H-8 enhances in vivo bone formation by hMSC, using a preclinical ectopic bone formation model in mice. Using functional screening of known H-8 targets, we demonstrated that inhibition of protein kinase G1 (PRKG1) and consequent activation of RhoA-Akt signaling is the main mechanism through which H-8 enhances osteogenesis. Our studies revealed PRKG1 as a novel negative regulator of OB differentiation and suggest that pharmacological inhibition of PRKG1 in hMSC implanted at the site of bone defect can enhance bone regeneration.

U2 - 10.1002/stem.2013

DO - 10.1002/stem.2013

M3 - Journal article

C2 - 25858613

SN - 1066-5099

VL - 33

SP - 2219

EP - 2231

JO - Stem Cells

JF - Stem Cells

IS - 7

ER -