How Cells Take Out the Trash
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Autophagy consists of a collection of cellular housecleaning processes responsible for recycling damaged cellular components. It is known to relate to longevity, as demonstrated in numerous animals studies in which aging is slowed via genetic or metabolic manipulation, and in which autophagy is seen to take place more energetically. This all seems logical, as aging is nothing more than an accumulation of unrepaired damage and the reactions to that damage, while autophagy seeks to minimize present damage before it causes more harm.

Since we've already touched on of autophagy and its relationship to longevity today, as well as the prospects for developing therapies based on increased levels of autophagy, I thought I'd point out this popular science article on the topic:

To keep themselves neat, tidy and above all healthy, cells rely on a variety of recycling and trash removal systems. If it weren't for these systems, cells could look like microscopic junkyards - and worse, they might not function properly.

One of the cell's trash processors is called the proteasome. It breaks down proteins, the building blocks and mini-machines that make up many cell parts. The barrel-shaped proteasome disassembles damaged or unwanted proteins, breaking them into bits that the cell can re-use to make new proteins. In this way, the proteasome is just as much a recycling plant as it is a garbage disposal.

Proteins aren't the only type of cellular waste. Cells also have to recycle compartments called organelles when they become old and worn out. For this task, they rely on an organelle called the lysosome, which works like a cellular stomach. Containing acid and several types of digestive enzymes, lysosomes digest unwanted organelles in a process termed autophagy.

While cells mainly use proteasomes and lysosomes, they have a couple of other options for trash disposal. Sometimes they simply hang onto their trash, performing the cellular equivalent of sweeping it under the rug. Scientists propose that the cell may pile all the unwanted proteins together in a glob called an aggregate to keep them from gumming up normal cellular machinery. If the garbage can't be digested by lysosomes, the cell can sometimes spit it out in a process called exocytosis. Once outside the cell, the trash may encounter enzymes that can take it apart, or it may simply form a garbage heap called a plaque. Unfortunately, these plaques outside the cell may be harmful, too.

Further study of the many ways cells take out the trash could lead to new approaches for keeping them healthy and preventing or treating disease.

Link: http://www.newswise.com/articles/how-cells-take-out-the-trash

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