What does decreased mitochondrial membrane potential mean?

328,329 Loss of mitochondrial membrane potential is a signal of bioenergetic stress and may result in the release of apoptotic factors leading to cell death.

How mitochondria enable apoptosis process?

Mitochondria play key roles in activating apoptosis in mammalian cells. Bcl-2 family members regulate the release of proteins from the space between the mitochondrial inner and outer membrane that, once in the cytosol, activate caspase proteases that dismantle cells and signal efficient phagocytosis of cell corpses.

What does mitochondrial membrane potential tell us?

The mitochondrial membrane potential (ΔΨm) generated by proton pumps (Complexes I, III and IV) is an essential component in the process of energy storage during oxidative phosphorylation. Together with the proton gradient (ΔpH), ΔΨm forms the transmembrane potential of hydrogen ions which is harnessed to make ATP.

How do mitochondria regulate apoptosis?

Mitochondria regulate caspase activation and cell death through an event termed mitochondrial outer membrane permeabilization (MOMP); this leads to the release of various mitochondrial intermembrane space proteins that activate caspases, resulting in apoptosis.

What causes mitochondrial membrane depolarization?

Short-term exposure to NO in mitochondria results in transient and reversible, mitochondrial depolarization [58]. In contrast, persistent inhibition of respiration [59], or high concentrations of NO [60] result in the collapse of the mitochondrial membrane potential, ATP depletion, and cell death.

What causes mitochondrial depolarization?

Moreover, there is a positive feedback loop between mitochondrial ROS production and SR Ca2+ release, i.e., leaky RyRs trigger more Ca2+ release resulting in more Ca2+ sequestered in mitochondria, which can trigger the opening of mPTP, leading to mitochondria depolarizations [34,35].

Which cell organelle is involved in apoptosis?

Mitochondria
Mitochondria are pivotal in the control of apoptosis, being involved not only in the intrinsic but also in the extrinsic pathway.

Which one has intrinsic mitochondrial pathway of apoptosis?

In the intrinsic pathway, the functional consequence of pro-apoptotic signaling is mitochondrial membrane perturbation and release of cytochrome c in the cytoplasm, where it forms a complex or apoptosome with apoptotic protease activating factor 1 (APAF1) and the inactive form of caspase-9.

What is mitochondrial membrane depolarization?

Definition: The process in which the membrane potential of the mitochondria changes in the depolarizing direction from the resting potential, from negative to positive.

What is involved in the regulation of apoptosis?

Regulation of apoptosis includes activation of certain membrane channels and release of apoptogenic proteins from the mitochondria into the cytosol, where they activate the terminal elements of a protease cascade pathway, which are capable of nuclear DNA fragmentation.

What is mitochondrial hyperpolarization?

Mitochondrial hyperpolarization (MHP), an early event of T-cell activation and death, appears to be mediated through inhibition of F0F1-ATPase or dephosphorylation of cytochrome c oxidase [44].

Which of the following proteins activates the mitochondrial pathway of apoptosis?

Which of the following proteins activates the mitochondrial pathway of apoptosis? A. The tumor suppressor protein p53, when activated in response to extensive DNA damage.

Which cell organelle is not involved in apoptosis?

Sol: (d) Mitochondria.

What is the difference between intrinsic and extrinsic apoptosis pathways?

The extrinsic pathway of apoptosis begins outside a cell, when conditions in the extracellular environment determine that a cell must die. The intrinsic pathway of apoptosis pathway begins when an injury occurs within the cell and the resulting stress activates the apoptotic pathway.

What activates intrinsic apoptosis?

The intrinsic apoptosis pathway is initiated by, for example, chemotherapy and/or radiotherapy. It is activated by a range of exogenous and endogenous stimuli, such as DNA damage, ischemia, and oxidative stress. Moreover, it plays an important function in development and in the elimination of damaged cells.

What is meant by depolarization?

Definition of depolarization 1 : the process of depolarizing something or the state of being depolarized. 2 physiology : loss of the difference in charge between the inside and outside of the plasma membrane of a muscle or nerve cell due to a change in permeability and migration of sodium ions to the interior …

What stimulates apoptosis?

In some cases it’s the type of stimuli and/or the degree of stimuli that determines if cells die by apoptosis or necrosis. At low doses, a variety of injurious stimuli such as heat, radiation, hypoxia and cytotoxic anticancer drugs can induce apoptosis but these same stimuli can result in necrosis at higher doses.

What causes apoptosis to occur?

Apoptosis plays important roles in physiology and pathology, and can be triggered by numerous stimuli, including ischemia, hypoxia, exposure to certain drugs and chemicals, immune reactions, infectious agents, high temperature, radiation, and various disease states.

What is the typical potential difference across a mitochondrial membrane?

The mitochondrial membrane potential, which is typically around 150 mV, represents the electrical component of the proton motive force [17].

What is the consequence of uncoupling mitochondrial oxidative phosphorylation?

What is the consequence of uncoupling mitochondrial oxidative phosphorylation? Increased oxygen consumption but halted ATP formation.

What are the effects of mitochondrial uncoupling?

Mitochondrial uncoupling, which decouples mitochondrial ATP synthesis from electron transport chain activity, creates a futile cycle that could drastically increase mitochondrial oxidation of acetyl-CoA and decrease mitochondrial acetyl-CoA concentration, leading to PDH activation and pyruvate influx.

What proteins trigger apoptosis?

P53 gene. The tumor suppressor gene p53 is a gene with a key role in apoptosis. The protein it codes for belongs to a family of proteins that has three members: P53, P63 and P73. All of them have about 60-70% amino-acid identity of the DNA-binding region and all three can induce apoptosis38.

What activates apoptosis?

Apoptosis is mediated by proteolytic enzymes called caspases, which trigger cell death by cleaving specific proteins in the cytoplasm and nucleus. Caspases exist in all cells as inactive precursors, or procaspases, which are usually activated by cleavage by other caspases, producing a proteolytic caspase cascade.