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Updated: Jul 7, 2026
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Chondrogenic Differentiation Induction of Adipose-derived Stem Cells by Centrifugal Gravity
Published on: February 24, 2017
mTOR signaling contributes to chondrocyte differentiation
Chanika Phornphutkul1, Ke-Ying Wu, Valerie Auyeung
1Department of Pediatrics, Division of Pediatric Endocrinology and Metabolism, Rhode Island Hospital and Brown University, Providence, Rhode Island 02903, USA. chanika_phornphutkul@brown.edu
Summary
Nutrient sensing via the mammalian Target Of Rapamycin (mTOR) pathway regulates chondrocyte differentiation and long bone growth. Inhibiting mTOR with rapamycin specifically impacts hypertrophic chondrocytes, affecting growth and differentiation markers.
Area of Science:
- Cell Biology
- Developmental Biology
- Biochemistry
Background:
- The mammalian Target Of Rapamycin (mTOR) is a key nutrient-sensing kinase regulating cellular functions.
- Chondrogenesis, the process of cartilage formation, is crucial for long bone development.
- Understanding nutrient-mediated regulation of chondrogenesis is vital for skeletal biology.
Purpose of the Study:
- To investigate the role of mTOR signaling in chondrogenesis using fetal rat metatarsal explants and an in situ model.
- To determine the specific effects of mTOR inhibition on chondrocyte proliferation, differentiation, and key molecular markers.
Main Methods:
- Utilized fetal rat metatarsal explants and in situ injections of rapamycin (mTOR inhibitor) in embryonic day 19 rats.
- Assessed cell proliferation via bromodeoxyuridine incorporation.
- Analyzed proteoglycan accumulation, collagen X expression, and Indian Hedgehog (Ihh) levels in the ATDC5 chondrogenic cell line.
Main Results:
- mTOR inhibition by rapamycin diminished insulin-stimulated growth in metatarsal explants, primarily affecting the hypertrophic zone.
- Rapamycin did not alter cell proliferation but inhibited proteoglycan and collagen X expression in ATDC5 cells.
- Rapamycin decreased Indian Hedgehog (Ihh) levels, an effect reversed by Ihh addition.
Conclusions:
- mTOR signaling modulates chondrocyte differentiation, potentially via regulation of Indian Hedgehog (Ihh).
- Nutrients, acting through mTOR, directly influence chondrocyte differentiation and long bone growth.
- These findings highlight mTOR as a critical regulator in skeletal development.
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