Related Experiment Video

Updated: Jun 8, 2025

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

18.8K

Roles of mTOR-p70S6K signaling pathway and HO-1 in ethylbenzene-induced hepatoxic effects in L02 cells

Siyu Liu1, Linlin Chen2, Hui Peng3

  • 1Department of Occupational Health Comprehensive Management, Shenzhen Prevention and Treatment Center for Occupational Diseases, Shenzhen, 518020, China; School of Public Health, Tianjin Medical University, Tianjin, 300070, China.

Food and Chemical Toxicology : an International Journal Published for the British Industrial Biological Research Association
|November 3, 2024
PubMed

Insights

Ethylbenzene (EB) harms liver cells by damaging mitochondria and causing excessive apoptosis and autophagy. This occurs through the inactivation of the mTOR-p70S6K signaling pathway, impacting liver cell viability.

Area of Science:

  • Hepatotoxicity
  • Cellular Signaling
  • Toxicology

Background:

  • Ethylbenzene (EB) exposure is linked to hepatotoxic effects, including oxidative damage and apoptosis, but the underlying mechanisms require further elucidation.
  • Previous in vivo studies suggested EB-induced liver damage, necessitating in vitro investigation to explore specific cellular pathways.
  • Understanding the role of signaling pathways like mTOR-p70S6K is crucial for comprehending EB's cellular toxicity.

Purpose of the Study:

  • To investigate the role of the mammalian target of rapamycin (mTOR)-p70S6K signaling pathway in ethylbenzene-induced hepatotoxicity in vitro.
  • To elucidate the cellular mechanisms, including oxidative stress, mitochondrial dysfunction, apoptosis, and autophagy, involved in EB's toxic effects on human hepatocytes.
  • To determine how EB exposure affects the expression of key molecules within the mTOR-p70S6K pathway and related cellular processes.

Main Methods:

  • Normal human hepatocytes (L02 cells) were treated with varying concentrations of ethylbenzene (0-10 mM) for 24 hours.
  • Cell viability assays, oxidative stress markers, mitochondrial function assessments, apoptosis, and autophagy evaluations were performed.
  • Western blotting and immunofluorescence were utilized to analyze the levels of mTOR-p70S6K pathway components, Atg proteins, and Heme oxygenase-1 (HO-1).
  • Experiments included treatment with an mTOR inhibitor to confirm pathway involvement.

Main Results:

  • Ethylbenzene exposure significantly reduced L02 cell viability.
  • EB treatment induced oxidative stress, mitochondrial impairments, excessive apoptosis, and autophagy in hepatocytes.
  • The study observed inactivation of the mTOR-p70S6K signaling cascade, evidenced by decreased levels of Atg family proteins and HO-1.
  • mTOR inhibitor treatment corroborated the findings regarding pathway suppression.
  • Oxidative stress was found to influence the passive upregulation of HO-1.

Conclusions:

  • Ethylbenzene induces hepatotoxicity in L02 cells by impairing mitochondria and promoting excessive apoptosis and autophagy.
  • The observed hepatotoxic effects are mediated through the suppression of the mTOR-p70S6K signaling pathway.
  • Oxidative stress plays a role in the cellular response to EB, potentially affecting HO-1 expression.
Keywords:
AutophagyEthylbenzeneHeme oxygenase-1HepatotoxicityOxidative stressmTOR-p70S6K pathway

More Related Videos

Assessment of Glutamine as a Fuel Source for Alveolar Macrophages Exposed to Chronic Ethanol Using an Extracellular Flux Bioanalyzer08:37

Assessment of Glutamine as a Fuel Source for Alveolar Macrophages Exposed to Chronic Ethanol Using an Extracellular Flux Bioanalyzer

Published on: November 15, 2024

281
Experimental Protocol for Detecting Mitochondrial Function in Hepatocytes Exposed to Organochlorine Pesticides08:39

Experimental Protocol for Detecting Mitochondrial Function in Hepatocytes Exposed to Organochlorine Pesticides

Published on: September 16, 2020

7.9K

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...
3.7K
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...
3.4K
Peroxisomes01:24

Peroxisomes

Peroxisomes are specialized organelles present in fungi, plant, and animal cells. It can vary in number, size, morphology, and activity depending on the type of tissue and the nutritional state of the cell. For example, cells with active lipid metabolism, such as adipocytes, neurons, and hepatocytes, have more peroxisomes than other cells in the body. Besides their primary role in breaking down complex organic molecules, peroxisomes can also synthesize specific macromolecules and participate in...
11.0K
Interactions Between Signaling Pathways01:19

Interactions Between Signaling Pathways

Signaling cascades usually lack linearity. Multiple pathways interact and regulate one another, allowing cells to integrate and respond to diverse environmental stimuli.
Convergence and divergence, and cross-talk between signaling pathways
Two distinct signaling pathways can converge on a single functional unit, which may either be a single protein or a complex of proteins. The response is either functionally distinct or synergistic between the two pathways but different from the response...
6.2K
MAPK Signaling Cascades01:07

MAPK Signaling Cascades

Mitogen-activated protein kinase, or MAPK pathway, activates three sequential kinases to regulate cellular responses such as proliferation, differentiation, survival, and apoptosis. The canonical MAPK pathway starts with a mitogen or growth factor binding to an RTK. The activated RTKs stimulate Ras, which recruits Raf or MAP3 Kinase (MAPKKK), the first kinase of the MAPK signaling cascade. Raf further phosphorylates and activates MEK or MAP2 Kinases (MAPKK), which in turn phosphorylates MAP...
5.2K
Electron Transport Chain: Complex I and II01:46

Electron Transport Chain: Complex I and II

The mitochondrial electron transport chain (ETC) is the main energy generation system in the eukaryotic cells. However, mitochondria also produce cytotoxic reactive oxygen species (ROS) due to the large electron flow during oxidative phosphorylation. While Complex I is one of the primary sources of superoxide radicals, ROS production by Complex II is uncommon and may only be observed in cancer cells with mutated complexes.
ROS generation is regulated and maintained at moderate levels necessary...
11.9K