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Discovering small molecules that inhibit adipogenesis and promote osteoblastogenesis: unique screening and Oncostatin
Katsuhiko Nawa1, Hirotaka Ikeno, Norikazu Matsuhashi
1Frontier Research Laboratories, Daiichi Sankyo Co., Ltd., 1-2-58 Hiromachi, Shinagawa-ku, Tokyo 140-8710, Japan.
Abstract:
Oncostatin M (OSM), one of the IL-6 family cytokines, inhibits adipogenic differentiation and stimulates osteoblastogenic differentiation from human bone marrow mesenchymal stem cells (hBMSCs). This functional study of OSM enabled us to develop a two-dimensional small-molecule screen that shifts hBMSC differentiation from adipocyte to osteoblast. Several structurally related compounds (isoxazoles) inhibited the accumulation of intracellular lipid droplets, whereas they promoted alkaline phosphatase activity and extracellular matrix calcification. Isoxazoles also reduced the expression of adipogenic transcription factor PPARγ and increased the levels of osteogenic transcription factors Runx2 and Osterix. They also induced the expression of the Wnt/β-catenin downstream gene and TOPflash reporter; however, the dephosphorylated β-catenin-active form was not significantly increased. Interestingly, the slight modification of the active compound led to a complete reversion of the dual differentiation activities. In summary, we have identified isoxazoles with anti-adipogenic and pro-osteogenic activities that provide a potential new tool for exploring the lineage commitment of mesenchymal stem cells and a possible lead for therapeutic intervention in osteopenia and osteoporosis.
Insights
Isoxazoles were identified as small molecules that inhibit fat cell differentiation and promote bone cell differentiation in human mesenchymal stem cells. These compounds offer potential therapeutic leads for bone loss conditions like osteoporosis.
Area of Science:
- Biochemistry
- Cell Biology
- Pharmacology
Background:
- Oncostatin M (OSM), an IL-6 family cytokine, influences mesenchymal stem cell (hMSC) differentiation.
- OSM inhibits adipogenesis and promotes osteoblastogenesis in hBMSCs.
Purpose of the Study:
- To develop a small-molecule screen to modulate hMSC differentiation from adipocytes to osteoblasts.
- To identify compounds that shift hMSC lineage commitment.
Main Methods:
- Two-dimensional small-molecule screening of isoxazole compounds.
- Assays for adipogenic (lipid droplet accumulation) and osteogenic (alkaline phosphatase activity, matrix calcification) differentiation.
- Analysis of key adipogenic (PPARγ) and osteogenic (Runx2, Osterix) transcription factors.
- Investigation of Wnt/β-catenin signaling pathway activation.
Main Results:
- Isoxazoles inhibited adipogenic differentiation and promoted osteogenic differentiation in hBMSCs.
- Compounds reduced PPARγ expression and increased Runx2 and Osterix levels.
- Isoxazoles induced Wnt/β-catenin pathway gene expression, though active β-catenin levels were not significantly elevated.
- Minor structural modifications reversed the observed dual differentiation activities.
Conclusions:
- Isoxazoles possess anti-adipogenic and pro-osteogenic properties.
- These compounds represent a novel tool for studying hMSC lineage commitment.
- Isoxazoles show potential as therapeutic leads for osteopenia and osteoporosis.