What is mitophagy and why under what circumstances does it occur in cells?

Mitophagy is the selective degradation of mitochondria by autophagy. It often occurs to defective mitochondria following damage or stress.

Which of the mitochondria membrane is porous?

The membrane of a mitochondrion is divided into the inner and outer membranes, distinctly divided into two aqueous compartments – outer and inner compartments. The outer membrane is very porous (containing the organelle), while the inner membrane is deeply-folded.

What triggers mitophagy?

► Mitophagy is specifically induced by mild and transient oxidative stress. ► Moderate levels of reactive oxygen species do not trigger non-selective autophagy. ► ROS and starvation induced mitophagy occurs in a DRP1-dependent manner. ► Starvation induced hyperfusion of mitochondria counteracts mitophagy.

Is mitophagy a form of autophagy?

Mitophagy as a Selective Form of Autophagy Although mitochondria can be engulfed non-selectively along with other cytosolic contents during bulk autophagy,31 both yeast and mammalian cells can selectively degrade damaged or superfluous mitochondria by mitophagy.

What is meant by Autophagosome?

Definition. Autophagosomes are double-membraned vesicles that contain cellular material slated to be degraded by autophagy. An isolation membrane or phagophore forms near autophagic cargo and expands until it encloses the cargo. Autophagosome formation depends on the activity of a type III PI3K lipid kinase.

How do you detect mitophagy?

Mitophagy flux is analyzed by the fluorescent intensity ratio of 440 nm and 550 nm. A strong signal at 440 nm indicates that mitophagy did not occur while a strong signal at 550 nm indicates mitophagy occurred. Mitophagy was detected using IN Cell Analyzer 1000.

Why does mitochondria have 2 membranes?

Mitochondria are shaped perfectly to maximize their productivity. They are made of two membranes. The fluid contained in the mitochondria is called the matrix. The folding of the inner membrane increases the surface area inside the organelle.

What are the two membranes of mitochondria?

As previously mentioned, mitochondria contain two major membranes. The outer mitochondrial membrane fully surrounds the inner membrane, with a small intermembrane space in between. The outer membrane has many protein-based pores that are big enough to allow the passage of ions and molecules as large as a small protein.

How do you stimulate mitophagy?

Physical exercise has been proposed as a nondrug treatment against different diseases for people of all ages [76]. In addition, it is suggested that regular exercise could promote an increase in mitophagy capacity [14] and produce effects on the mitochondrial life cycle (Table 2).

What type of autophagy is mitophagy?

(3) Macroautophagy is the most extensively studied autophagy, which involves formation of double membrane structures that encircle proteins, lipids, and organelles. Degradation of mitochondria through the macroautophagy pathway is also termed mitophagy.

How many types of cell death are there?

Morphologically, cell death can be classified into four different forms: apoptosis, autophagy, necrosis, and entosis.

What is the function of Autophagosome?

An autophagosome is a spherical structure with double layer membranes. It is the key structure in macroautophagy, the intracellular degradation system for cytoplasmic contents (e.g., abnormal intracellular proteins, excess or damaged organelles, invading microorganisms).

How are autophagosomes formed in the mitochondria?

Autophagy is initiated by isolation membranes, which form and elongate as they engulf portions of the cytoplasm and organelles. Eventually isolation membranes close to form double membrane-bound autophagosomes and fuse with lysosomes to degrade their contents.

When was electron microscopy used to study autophagosome?

In the late 1950s, electron microscopy (EM) studies identified the autophagosome as a mitochondria surrounded by a larger vesicular structure (Rhodin 1954). Since this discovery, EM has been the main tool used to study autophagy (Rhyu 2017).

How are autophagosomes different from normal macroautophagy?

Macroautophagy is characterized by unique morphological features, including the sequestering vesicles known as autophagosomes which differ from other vesicles that bud from preexisting organelles (Fig. 1 ). Although autophagy is initiated, normal autolysosome’s formation cannot be followed.

Which is part of the mitochondria binds ATG14?

The ER-resident SNARE protein syntaxin 17 (STX17) binds ATG14 and recruits it to the ER–mitochondria contact site. These results provide new insight into organelle biogenesis by demonstrating that the ER–mitochondria contact site is important in autophagosome formation.