Related Experiment Video

Updated: May 30, 2026

Isolation of Primary Mouse Hepatocytes for Nascent Protein Synthesis Analysis by Non-radioactive L-azidohomoalanine Labeling Method
08:04

Isolation of Primary Mouse Hepatocytes for Nascent Protein Synthesis Analysis by Non-radioactive L-azidohomoalanine Labeling Method

Published on: October 23, 2018

Impaired autophagy due to constitutive mTOR activation sensitizes TSC2-null cells to cell death under stress

Shukie Ng1, You-Tong Wu, Bo Chen

  • 1Department of Epidemiology and Public Health, Yong Loo Lin School of Medicine, National University of Singapore, Singapore.

Autophagy
|August 3, 2011
PubMed

Insights

Cells lacking TSC2 show impaired autophagy due to mTORC1 activation, increasing cell death sensitivity. Restoring autophagy rescues these cells, suggesting autophagy-targeted therapies for Tuberous Sclerosis Complex (TSC) pathologies.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • Cells deficient in TSC1 or TSC2 exhibit heightened sensitivity to cell death triggers.
  • Tuberous Sclerosis Complex (TSC) is a genetic disorder linked to dysregulation of the TSC1/TSC2-mTOR pathway.

Purpose of the Study:

  • To investigate the role of autophagy in the increased susceptibility of TSC2-null cells to cell death.
  • To elucidate the relationship between mTORC1 signaling, autophagy, and cell death in the context of TSC2 deficiency.

Main Methods:

  • Utilized TSC2 (-/-) mouse embryonic fibroblasts (MEFs) to assess autophagy and cell death.
  • Manipulated autophagy using chloroquine and Atg7 knockdown.
  • Modulated mTORC1 activity via raptor knockdown and rapamycin treatment.
  • Examined the effects of nutrient supplementation (IGF-1, leucine) on cell death.

Main Results:

  • TSC2-null MEFs displayed enhanced apoptosis upon amino acid starvation and hypoxia.
  • Basal and inducible autophagy were impaired in TSC2 (-/-) MEFs due to constitutive mTORC1 activation.
  • Autophagy suppression sensitized wild-type cells but not TSC2-null cells to starvation-induced death.
  • Inhibition of mTORC1 restored autophagy and rescued TSC2 (-/-) cells from cell death.
  • Nutrient supplementation exacerbated cell death in TSC2 (-/-) cells while reducing it in TSC2 (+/+) cells.

Conclusions:

  • Constitutive mTORC1 activation in TSC2-null cells suppresses autophagy, leading to increased susceptibility to stress-induced cell death.
  • These findings highlight the intricate interplay between mTOR, autophagy, and cell death.
  • The study supports autophagy-targeted interventions for TSC-related diseases.

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...
Abnormal Proliferation02:23

Abnormal Proliferation

Under normal conditions, most adult cells remain in a non-proliferative state unless stimulated by internal or external factors to replace lost cells. Abnormal cell proliferation is a condition in which the cell's growth exceeds and is uncoordinated with normal cells. In such situations, cell division persists in the same excessive manner even after cessation of the stimuli, leading to persistent tumors. The tumor arises from the damaged cells that replicate to pass the damage to the daughter...
Autophagic Cell Death01:18

Autophagic Cell Death

Christian de Duve discovered “autophagy,” a process in which cellular components are engulfed by membrane-bound organelles called autophagosomes. The autophagosomes then fuse with lysosomes to digest the enclosed contents. Autophagy is generally activated in cells to prevent cell death. However, cell death is triggered when the damage is beyond repair.
Autophagy and Apoptosis
Autophagy can activate apoptosis. In normal conditions, the autophagy activating protein Beclin-1 and pro-apoptotic...
Cellular Injury V: Apoptosis and Autophagy01:22

Cellular Injury V: Apoptosis and Autophagy

Cells respond to damage and stress through highly coordinated processes that decide whether they survive or undergo controlled self-destruction. Two major pathways involved in this regulation are apoptosis, a type of programmed cell death, and autophagy, a survival mechanism that helps cells adapt to adverse conditions.ApoptosisApoptosis removes aged or injured cells to maintain tissue balance. During this process, the cell shrinks, chromatin condenses and fragments, and membrane-bound...