β1 integrin, ILK and mTOR regulate collagen synthesis in mechanically loaded tendon cells

Sci Rep. 2020 Jul 28;10(1):12644. doi: 10.1038/s41598-020-69267-6.

Abstract

Tendons are specialized tissues composed primarily of load-responsive fibroblasts (tenocytes) embedded in a collagen-rich extracellular matrix. Habitual mechanical loading or targeted exercise causes tendon cells to increase the stiffness of the extracellular matrix; this adaptation may occur in part through collagen synthesis or remodeling. Integrins are likely to play an important role in transmitting mechanical stimuli from the extracellular matrix to tendon cells, thereby triggering cell signaling pathways which lead to adaptive regulation of mRNA translation and protein synthesis. In this study, we discovered that mechanical stimulation of integrin β1 leads to the phosphorylation of AKT, an event which required the presence of integrin-linked kinase (ILK). Repetitive stretching of tendon cells activates the AKT and mTOR pathways, which in turn regulates mRNA translation and collagen expression. These results support a model in which integrins are an upstream component of the mechanosensory cellular apparatus, regulating fundamental tendon cell functions relevant to exercise-induced adaptation and mechanotherapy.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Bioartificial Organs*
  • Biomechanical Phenomena
  • Cell Survival
  • Collagen / metabolism*
  • Fibroblasts / cytology
  • Fibroblasts / metabolism
  • Humans
  • Integrin beta1 / genetics
  • Integrin beta1 / metabolism*
  • Male
  • Mechanotransduction, Cellular*
  • Phosphorylation
  • Protein Serine-Threonine Kinases / genetics
  • Protein Serine-Threonine Kinases / metabolism*
  • Signal Transduction
  • TOR Serine-Threonine Kinases / genetics
  • TOR Serine-Threonine Kinases / metabolism*
  • Tendons / cytology
  • Tendons / metabolism*

Substances

  • Integrin beta1
  • Itgb1 protein, human
  • Collagen
  • integrin-linked kinase
  • MTOR protein, human
  • Protein Serine-Threonine Kinases
  • TOR Serine-Threonine Kinases