How Cells Clean House
Worn-out proteins, malfunctioning organelles, invading microorganisms: all are swept up by tiny internal "vacuum cleaners" that keep a living cell healthy. If the process, called autophagy, can be kept in good working order, aging itself might be delayed
By Daniel J. Klionsky and Vojo Deretic
April, 2008
Key Concepts
Inside the cytoplasm of a living cell, organelles called autophagosomes continually engulf bits of cytoplasm, along with damaged cell parts and invading bacteria and viruses. The “sweepings” are carried to digestive organelles for breakup and recycling. The process is called autophagy.
Cell biologists are learning about autophagy in great detail by tracing the protein signals that drive and control the process.
A fuller understanding of autophagy is opening up new options for treating cancer, infectious disease, immune disorders and dementia, and it may one day even help to slow
Every once in a while biologists come to realize that what was at one time regarded as a minor and relatively obscure cellular process is, in fact, of central importance. Not only is the process ubiquitous, but by virtue of that ubiquity it also plays a role in a broad range of normal and disease states. So it was with the discovery of the role of nitric oxide in the circulatory system, a discovery that led to a Nobel Prize, as well as to many beneficial drugs. Now another formerly obscure process known as autophagy is suddenly claiming extraordinary scientific attention.
In basic outline, autophagy (from the Greek, meaning “self-eating”) is simple enough. Within every cell but outside the nucleus lies the cytoplasm, a kind of formless jelly supported by a skeletal matrix, in which a vast and intricate population of large molecules, or macromolecules, and specialized functional subunits called organelles is suspended. The workings of the cytoplasm are so complex—rather like some of today’s computer systems—that it is constantly becoming gummed up with the detritus of its ongoing operations. Autophagy is, in part, a cleanup process: the trash hauling that enables a cell whose cytoplasm is clotted with old bits of protein and other unwanted sludge to be cleaned out.
Adam Questell
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