Novel Hedgehog Agonists Promote Osteoblast Differentiation in Mesenchymal Stem Cells

Abstract

Hedgehog (Hh) family members are involved in multiple cellular processes including proliferation, migration, differentiation, and cell fate determination. Recently, the novel Hh agonists Hh-Ag 1.3 and 1.7 were identified in a high-throughput screening of small molecule compounds that activate the expression of Gli1, a target of Hh signaling. This study demonstrates that Hh-Ag 1.3 and 1.7 strongly activate the expression of endogenous Gli1 and promote osteoblast differentiation in the mesenchymal stem cell line C3H10T1/2. Both compounds stimulated alkaline phosphatase activity in a dose-dependent manner, and induced osteoblast marker gene expression in C3H10T1/2 cells, which indicated that they had acquired an osteoblast identity. Of the markers, the expression of osterix/Sp7, a downstream target of runt-related transcription factor (Runx)2, was induced by Hh-Ag 1.7, which also rescued the osteoblast differentiation defect of RD-127, a mesenchymal cell line from Runx2-deficient mice. Hh-Ags also activated canonical Wnt signaling and synergized with low doses of BMP-2 to enhance osteoblastic potential. Thus, Hh-Ag 1.7 could be useful for bone healing in individuals with abnormalities in osteogenesis, such as osteoporosis patients and the elderly, and can contribute to the development of novel therapeutics for the treatment of bone fractures and defects.

Dynamic expression of SMAD3 is critical in�osteoblast differentiation of PDMCs

“…In addition, appropriate osteoblast calcification or bone mineralization is essential for complete bone formation (13)(14)(15). The process of bone regeneration has the potential to treat defects in bone healing in patients with osteoporosis with bone fractures or abnormalities in osteogenesis (9,16,17).…”

Lithium enhances alveolar bone formation during orthodontic retention in rats

“…During skeletal development, Runx2 regulates Osterix expression at an early stage of osteoblast differentiation, due to crosstalk between the Wnt, IHH and FGF signalling pathways . Indeed, Osterix expression was absent in Runx2‐deficient mice; as it seems, Osterix functioned downstream of Runx2 during osteoblast differentiation and Wnt signalling is required for progression from the Runx2 + stage to the Runx2 + Osterix + stage, and then, to the mature osteoblast stage . However, Runx2 also promotes osteoclastogenesis and bone resorption in some conditions.…”

Effect of Qing’e formula on the in vitro differentiation of bone marrow-derived mesenchymal stem cells from proximal femurs of postmenopausal osteoporotic mice

“…Indeed, a large number of studies have shown that TGF-β plays a pivotal role in bone regeneration and is involved in the formation and growth of bone during embryogenesis [ 25 ]. During the early stages of bone formation in newborns, TGF-β1 and TGF-β2 in particular are expressed in the cartilage and periosteum, and TGF-β1 has been shown to promote the proliferation and differentiation of mesenchymal cells into mature bone cells in these tissues [ 26 ]. Mechanistically, TGF-β1 mainly functions to regulate the transcription and activity of genes essential for mesenchymal cell differentiation in addition to promoting the synthesis of extracellular matrix (ECM) and ECM associated proteins (e.g., collagen, osteonectin, and osteopontin) and increasing the rate of bone matrix deposition [ 27 ].…”