Related Experiment Video

Updated: Sep 20, 2026

Detection of Mitochondria Membrane Potential to Study CLIC4 Knockdown-induced HN4 Cell Apoptosis In Vitro
13:20

Detection of Mitochondria Membrane Potential to Study CLIC4 Knockdown-induced HN4 Cell Apoptosis In Vitro

Published on: July 17, 2018

The tumor suppressor cybL, a component of the respiratory chain, mediates apoptosis induction

Timur Albayrak1, Volker Scherhammer, Nicole Schoenfeld

  • 1Max-Planck-Institute for Biochemistry, 82152 Martinsried, Germany.

Molecular Biology of the Cell
|August 20, 2003
PubMed

Insights

Mitochondrial complex II, including cytochrome bL (cybL), acts as a sensor for apoptosis induction. Its deficiency confers resistance to cell death, potentially explaining complex II inactivation in tumors.

Area of Science:

  • Cell Biology
  • Biochemistry
  • Genetics

Background:

  • Apoptosis, or programmed cell death, is crucial for development and disease.
  • Mitochondria play a central role in regulating apoptosis.
  • Components of the respiratory chain, like complex II, are increasingly implicated in cellular regulation.

Purpose of the Study:

  • To identify genes that induce apoptosis using a high-throughput genetic screen.
  • To investigate the role of cytochrome bL (cybL), a component of respiratory chain complex II, in apoptosis.
  • To determine if complex II functions as a sensor for apoptosis induction.

Main Methods:

  • High-throughput genetic screening for apoptosis-inducing genes.
  • Cloning and characterization of proapoptotic genes, including cybL.
  • Analysis of cellular responses to cybL expression and deficiency, including complex II activity, reactive oxygen species (ROS) generation, and drug/Fas receptor sensitivity.

Main Results:

  • Isolation of several proapoptotic genes localized to mitochondria, including cybL.
  • Expression of cybL induces cell death, accompanied by transient inhibition of complex II and increased ROS production.
  • Cells with constitutive cybL deficiency exhibit resistance to proapoptotic drugs and Fas receptor-mediated cell death.

Conclusions:

  • Respiratory chain complex II functions as a sensor for apoptosis induction.
  • cybL plays a critical role in mediating apoptosis.
  • The findings provide a potential explanation for the observed inactivation of complex II in tumors.

More Related Videos

Knockdown of FAM83A to Verify Its Role in Cervical Cancer Cell Growth and Cisplatin Sensitivity04:20

Knockdown of FAM83A to Verify Its Role in Cervical Cancer Cell Growth and Cisplatin Sensitivity

Published on: February 9, 2024

Activation of Apoptosis by Cytoplasmic Microinjection of Cytochrome c07:42

Activation of Apoptosis by Cytoplasmic Microinjection of Cytochrome c

Published on: June 29, 2011

Related Concept Videos

The Intrinsic Apoptotic Pathway01:31

The Intrinsic Apoptotic Pathway

Internal cellular stress, such as cellular injury or hypoxia, triggers intrinsic apoptosis. The B-cell lymphoma 2 (Bcl-2) family of proteins are the primary regulators of the intrinsic apoptotic pathway. For example, during DNA damage, checkpoint proteins, such as Ataxia Telangiectasia Mutated (ATM protein) and Checkpoints Factor-2 (Chk2) proteins, are activated. These proteins phosphorylate p53 which further activates pro-apoptotic proteins, such as Bax, Bak, PUMA, and Noxa, and inhibits...
The Extrinsic Apoptotic Pathway01:17

The Extrinsic Apoptotic Pathway

The extrinsic apoptotic pathway is initiated when extracellular death-inducing signals, such as specific cytokines, activate the death receptors expressed on the cell surface. The immune cells involved in this pathway are natural killer cells (NK cells) and cytotoxic T-lymphocytes. NK cells are critical in innate immune response, while cytotoxic T-lymphocytes are associated with adaptive immune response. These cells recognize specific receptors expressed on the altered cells and activate...
The Retinoblastoma Gene01:20

The Retinoblastoma Gene

Tumor suppressor genes are normal genes that can slow down cell division, repair DNA mistakes, or program the cells for apoptosis in case of irreparable damage. Hence, they play an essential role in preventing the proliferation of damaged cells.
The first-ever tumor suppressor gene called Rb was identified in retinoblastoma - a rare eye tumor in children. In inherited forms of the disease, a child inherits one defective copy of the Rb gene, which predisposes them to retinoblastoma. However,...
Cancer-Critical Genes II: Tumor Suppressor Genes01:05

Cancer-Critical Genes II: Tumor Suppressor Genes

Genes usually encode proteins necessary for the proper functioning of a healthy cell. Mutations can often cause changes to the gene expression pattern, thereby altering the phenotype.
When the function of certain critical genes, especially those involved in cell cycle regulation and cell growth signaling cascades, gets disrupted, it upsets the cell cycle progression. Such cells with unchecked cell cycles start proliferating uncontrollably and eventually develop into tumors.
Such genes that act...
Cancer-Critical Genes II: Tumor Suppressor Genes01:05

Cancer-Critical Genes II: Tumor Suppressor Genes

Genes usually encode proteins necessary for the proper functioning of a healthy cell. Mutations can often cause changes to the gene expression pattern, thereby altering the phenotype.
When the function of certain critical genes, especially those involved in cell cycle regulation and cell growth signaling cascades, gets disrupted, it upsets the cell cycle progression. Such cells with unchecked cell cycles start proliferating uncontrollably and eventually develop into tumors.
Such genes that act...
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...