Autophagy: The Powerful of Immune Response
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Date
2019-12-29
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Medcrave
Abstract
Introduction
Autophagy is an intracellular degradation system that
delivers cytoplasmic constituents to the lysosome.
Despite its simplicity, recent progress has demonstrated
that autophagy plays a wide variety of physiological
and pathophysiological roles, which are sometimes
complex. Autophagy consists of several sequential steps
sequestration, transport to lysosomes, degradation, and
utilization of degradation products and each step may
exert different function. This process is quite distinct
from endocytosis-mediated lysosomal degradation of
extracellular and plasma membrane proteins. There
are three types of autophagy macroautophagy, micro
autophagy, and chaperone-mediated autophagy and the
term “autophagy” usually indicates macroautophagy unless
otherwise specified. Autophagy is mediated by a unique
organelle called the autophagosome. As autophagosomes
engulf a portion of cytoplasm, autophagy is generally
thought to be a nonselective degradation system. This
feature is in marked contrast to the ubiquitin-proteasome
system, which specifically recognizes only ubiquitinated
proteins for proteasomal degradation. It is therefore
reasonable to assume that the ubiquitin-proteasome system
has numerous specific functions because it can selectively
degrade thousands of substrates. Recent studies have
clearly demonstrated that autophagy has a greater variety
of physiological and pathophysiological roles than expected,
such as starvation adaptation, intracellular protein and
organelle clearance, development, anti-aging, elimination
of microorganisms, cell death, tumor suppression, and
antigen presentation. Additionally, in some situations, the
contribution of autophagy seems to be very complicated.
For example, it is very difficult to generalize the role of
autophagy in cancer and cell death [1].