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mTORC1 Overactivation Leads to Abnormalities in Skeletal Development

Sayuki Iwahashi1, Kazuya Tokumura1, Gyujin Park1

  • 1Laboratory of Pharmacology, Department of Bioactive Molecules, Gifu Pharmaceutical University.

Biological & Pharmaceutical Bulletin
|December 3, 2020
PubMed

Insights

The Tuberous Sclerosis Complex (Tsc) gene regulates mTORC1, a key factor in skeletal development. Inactivating Tsc in embryonic mesenchymal cells disrupts skeletal formation, highlighting its crucial role in skeletogenesis.

Area of Science:

  • Cellular Biology
  • Developmental Biology
  • Genetics

Background:

  • The mechanistic/mammalian target of rapamycin complex-1 (mTORC1) pathway is crucial for cellular processes and is tightly regulated by Tuberous Sclerosis Complex 1 (Tsc1) and Tsc2.
  • Previous studies indicate mTORC1's essential role in skeletogenesis, with its inactivation in mesenchymal cells and chondrocytes causing skeletal abnormalities.

Purpose of the Study:

  • To investigate the specific role of mTORC1 hyperactivation in embryonic skeletal development.
  • To determine the cell-type specificity of Tsc complex-mediated mTORC1 signaling in skeletogenesis.

Main Methods:

  • Utilized mouse genetic models with cell-type specific deletion of Tsc1.
  • Employed Prx1-Cre, Col2a1-Cre, and Osx-Cre driver lines to inactivate Tsc1 in distinct embryonic cell populations.
  • Analyzed skeletal abnormalities in appendicular and axial skeletons.

Main Results:

  • Inactivation of Tsc1 in undifferentiated mesenchymal cells (Prx1-Cre) resulted in appendicular skeletal defects due to mTORC1 hyperactivation.
  • Tsc1 deletion in chondrocytes (Col2a1-Cre) or osteoprogenitors (Osx-Cre) did not lead to observable skeletal abnormalities.
  • These findings pinpoint undifferentiated mesenchymal cells as critical mediators of mTORC1's influence on skeletal development.

Conclusions:

  • Tsc complex-mediated mTORC1 signaling in undifferentiated embryonic mesenchymal cells is essential for normal skeletal development.
  • mTORC1's role in skeletogenesis is cell-type specific, with mesenchymal cells being a key regulatory population.
  • Targeting mTORC1 in specific embryonic cell types may offer therapeutic avenues for skeletal disorders.
Keywords:
mechanistic/mammalian target of rapamycin complex-1 (mTORC1)skeletogenesistuberous sclerosis complex 1undifferentiated mesenchymal cell

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