autophagy of peroxisome

Definition

Target type: biologicalprocess

The process in which peroxisomes are delivered to a type of vacuole and degraded in response to changing nutrient conditions. [GOC:autophagy, PMID:10547367, PMID:20083110]

Autophagy of peroxisomes, also known as pexophagy, is a highly regulated cellular process essential for the degradation and removal of dysfunctional or surplus peroxisomes. This process is crucial for maintaining cellular homeostasis and preventing the accumulation of toxic byproducts.

The process begins with the recognition of the target peroxisome. This recognition is mediated by specific proteins, including the autophagy receptor proteins p62/SQSTM1 and NBR1, which bind to ubiquitin chains attached to the peroxisome surface. Ubiquitination of peroxisomes often occurs due to oxidative stress, aging, or other forms of damage.

Once the target peroxisome is recognized, it is engulfed by a double-membrane structure called an autophagosome. This engulfment process is driven by the formation of a phagophore, a cup-shaped membrane structure that expands and encloses the peroxisome. The phagophore then closes, forming the autophagosome.

The autophagosome subsequently fuses with lysosomes, which are organelles containing hydrolytic enzymes. The fusion of these two compartments creates a hybrid organelle called an autolysosome. The hydrolytic enzymes within the autolysosome degrade the peroxisome's contents, including its proteins, lipids, and DNA.

The degradation products of the peroxisome are then recycled back into the cytoplasm, where they can be reused for other cellular processes. This recycling process ensures that the cellular building blocks are not wasted and can be used to generate new molecules.

Pexophagy is a highly regulated process involving numerous proteins and signaling pathways. Some key regulators of pexophagy include the Atg proteins, which are essential for the formation of autophagosomes, and the TORC1 complex, which senses nutrient availability and regulates autophagy initiation.

Pexophagy plays critical roles in various cellular processes, including:

* **Maintaining peroxisome quality control:** By removing damaged or dysfunctional peroxisomes, pexophagy prevents the accumulation of toxic substances and ensures the proper function of the peroxisome population.
* **Regulating peroxisome number:** Pexophagy helps to maintain the appropriate number of peroxisomes in the cell by degrading excess organelles.
* **Responding to cellular stress:** Pexophagy is induced under conditions of stress, such as starvation or oxidative stress, allowing the cell to recycle cellular components for energy production and survival.

Dysregulation of pexophagy has been implicated in various human diseases, including neurodegenerative disorders, metabolic diseases, and cancer. Understanding the complex mechanisms of pexophagy is crucial for developing therapeutic strategies for these conditions.'
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Proteins (1)

Compounds (23)