Related Experiment Video

Updated: Jul 20, 2026

A Mouse Model of Mechanotransduction-driven, Human-like Hypertrophic Scarring
05:54

A Mouse Model of Mechanotransduction-driven, Human-like Hypertrophic Scarring

Published on: November 29, 2024

mTOR pathway as a target in tissue hypertrophy

Chung-Han Lee1, Ken Inoki, Kun-Liang Guan

  • 1Life Science Institute, University of Michigan, Ann Arbor, MI 48109, USA. chunghl@umich.edu

Annual Review of Pharmacology and Toxicology
|September 14, 2006
PubMed

Insights

The mammalian target of rapamycin (mTOR) pathway regulates cell growth. Aberrant mTORC1 activation, often due to tumor suppressor loss, drives tissue hypertrophy, offering clinical insights.

Area of Science:

  • Biochemistry
  • Cell Biology
  • Physiology

Background:

  • The mammalian target of rapamycin (mTOR) pathway is a critical regulator of cell growth.
  • mTOR functions via two complexes, mTORC1 and mTORC2, distinguished by protein partners and rapamycin sensitivity.
  • Dysregulation of tumor suppressors TSC1/TSC2 leads to mTORC1 hyperactivation, impacting cell size control.

Purpose of the Study:

  • To review the biochemical regulation of the mTOR pathway concerning cell size.
  • To explore the clinical significance of mTOR in cell size regulation and hypertrophy.

Main Methods:

  • Literature review of biochemical regulation of mTOR.
  • Analysis of clinical examples of mTOR-associated hypertrophy.

Main Results:

  • TORC1 activation is linked to both physiological and pathological tissue hypertrophy.
  • Clinical conditions such as muscle hypertrophy, vascular restenosis, and kidney hypertrophy involve TORC1 activation.

Conclusions:

  • Understanding mTOR pathway regulation is key to comprehending aberrant cell size.
  • Targeting mTOR may offer therapeutic strategies for conditions characterized by abnormal cell growth.

Related Concept Videos

mTOR Signaling and Cancer Progression03:03

mTOR Signaling and Cancer Progression

The mammalian target of rapamycin or mTOR protein was discovered in 1994 due to its direct interaction with rapamycin. The protein gets its name from a yeast homolog called TOR. The mTOR protein complex in mammalian cells plays a major role in balancing anabolic processes such as the synthesis of proteins, lipids, and nucleotides and catabolic processes, such as autophagy in response to environmental cues, such as availability of nutrients and growth factors.
The mTOR pathway or the...
mTOR Signaling and Cancer Progression03:03

mTOR Signaling and Cancer Progression

The mammalian target of rapamycin or mTOR protein was discovered in 1994 due to its direct interaction with rapamycin. The protein gets its name from a yeast homolog called TOR. The mTOR protein complex in mammalian cells plays a major role in balancing anabolic processes such as the synthesis of proteins, lipids, and nucleotides and catabolic processes, such as autophagy in response to environmental cues, such as availability of nutrients and growth factors.
The mTOR pathway or the...
PI3K/mTOR/AKT Signaling Pathway01:22

PI3K/mTOR/AKT Signaling Pathway

The mammalian target of rapamycin  (mTOR) is a serine/threonine kinase that regulates growth, proliferation, and cell survival in response to hormones, growth factors, or nutrient availability. This kinase exists in two structurally and functionally distinct forms: mTOR complex 1  (mTORC1) and mTOR complex 2  (mTORC2). The first form (mTORC1) is composed of a rapamycin-sensitive Raptor and proline-rich Akt substrate, PRAS40. In contrast,  mTORC2 consists of a rapamycin-insensitive companion...
Cellular Adaptation II: Hypertrophy01:26

Cellular Adaptation II: Hypertrophy

Hypertrophy is the increase in the size of individual cells, resulting in the enlargement of a tissue or organ. Unlike hyperplasia, which involves an increase in cell number, hypertrophy is characterized by an increase in cell volume. This process often occurs in response to higher functional demand or hormonal stimulation, leading to the production of more structural proteins and organelles, thereby enhancing the cells' work capacity.There are two primary types of hypertrophy: physiological...
TGF - β Signaling Pathway01:16

TGF - β Signaling Pathway

The TGF-β signaling pathway regulates cell growth, differentiation, adhesion, motility, and development. TGF-β ligands that induce TGF-β signaling are synthesized in their latent form. Several proteases or cell surface receptors such as integrins act upon the latent form, releasing the active ligand. There are three types of mammalian TGF-βs: (TGF-β1, TGF-β2, and TGF-β3) that bind as homodimers or heterodimers to TGF-β receptors. The TGF-β receptors are of three kinds RI, RII, and RIII. The RI...
Regulation of Angiogenesis and Blood Supply01:24

Regulation of Angiogenesis and Blood Supply

Rapidly dividing tumors, embryos, and wounded tissues require more oxygen than usual, lowering the oxygen concentration in the blood. At low oxygen or hypoxic conditions, an oxygen-sensitive transcription factor called the hypoxia-inducible factor 1 or HIF1 is activated. HIF1 is a dimeric protein of alpha (ɑ) and beta (β) subunits.  Under optimal oxygen conditions, HIF1β is present in the nucleus while HIF1ɑ remains in the cytosol. HIF1ɑ is hydroxylated by prolyl hydroxylase and factor...