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Mitochondrial role in life and death of the cell
1Department of Biochemistry and Center for Cellular and Molecular Biology, National Yang-Ming University, Taipei, Taiwan, Republic of China.
Abstract:
Mitochondria are the major ATP producer of the mammalian cell. Moreover, mitochondria are also the main intracellular source and target of reactive oxygen species (ROS) that are continually generated as by-products of aerobic metabolism in human cells. A low level of ROS generated from the respiratory chain was recently proposed to take part in the signaling from mitochondria to the nucleus. Several structural characteristics of mitochondria and the mitochondrial genome enable them to sense and respond to extracellular and intracellular signals or stresses in order to sustain the life of the cell. It has been established that mitochondrial respiratory function declines with age, and that defects in the respiratory chain increase the production of ROS and free radicals in mitochondria. Within a certain concentration range, ROS may induce stress responses of the cell by altering the expression of a number of genes in order to uphold energy metabolism to rescue the cell. However, beyond this threshold, ROS may elicit apoptosis by induction of mitochondrial membrane permeability transition and release of cytochrome c. Intensive research in the past few years has established that mitochondria play a pivotal role in the early phase of apoptosis in mammalian cells. In this article, the role of mitochondria in the determination of life and death of the cell is reviewed on the basis of recent findings gathered from this and other laboratories.
Insights
Mitochondria produce ATP and reactive oxygen species (ROS). While low ROS levels signal to the nucleus, excessive ROS triggers apoptosis, highlighting mitochondria
Area of Science:
- Cell Biology
- Mitochondrial Function
- Apoptosis Signaling
Background:
- Mitochondria are central to cellular energy production (ATP) and are a primary source/target of reactive oxygen species (ROS).
- ROS, by-products of aerobic metabolism, play dual roles in cell signaling and stress response.
- Mitochondrial function declines with age, increasing ROS production and potentially leading to cell death.
Purpose of the Study:
- To review the pivotal role of mitochondria in initiating apoptosis in mammalian cells.
- To explore how mitochondria sense and respond to cellular signals and stresses.
- To elucidate the dual role of ROS in cellular life and death decisions.
Main Methods:
- Review of existing literature and recent findings on mitochondrial function and apoptosis.
- Analysis of the relationship between mitochondrial respiratory chain function, ROS production, and cellular fate.
- Examination of signaling pathways involving mitochondria, ROS, and gene expression.
Main Results:
- Mitochondria are critical regulators of apoptosis, particularly in its early stages.
- Mitochondrial defects and increased ROS production are linked to aging and cell death.
- ROS can induce protective stress responses at low levels but trigger apoptosis at higher concentrations.
Conclusions:
- Mitochondria play a decisive role in determining cellular life and death.
- The balance of ROS production and signaling is crucial for cell survival and apoptosis.
- Understanding mitochondrial dynamics is key to comprehending cellular fate and age-related diseases.