Autophagy

For more information, log on to- http://shomusbiology.weebly.com/ Download the study materials here- http://shomusbiology.weebly.com/bio-materials.html Autophagy (or autophagocytosis) (from the Greek words, auto "self" and phagein "to eat"), is the basic catabolic mechanism that involves cell degradation of unnecessary or dysfunctional cellular components through the actions of lysosomes. [1] The breakdown of cellular components can ensure cellular survival during starvation by maintaining cellular energy levels.[1] Autophagy, if regulated, ensures the synthesis, degradation and recycling of cellular components.[1] During this process, targeted cytoplasmic constituents are isolated from the rest of the cell within the autophagosomes, which are then fused with lysosomes and degraded or recycled.[2] There are three different forms of autophagy that are commonly described; macroautophagy, microautophagy and chaperone-mediated autophagy.[3] In the context of disease, autophagy has been seen as an adaptive response to survival, whereas in other cases it appears to promote cell death and morbidity.[2] The name "autophagy" was coined by Belgian biochemist Christian de Duve in 1963 The process of atuophagy was first observed by Keith R. Porter and his postdoctoral student Thomas Ashford at the Rockefeller Institute. In January 1962 they reported that there was increased number of lysosomes in the liver cells of rat after addition of glucagon, and that some displaced lysosomes towards the centre of the cell contained other cell organelles such as mitochondria. This was the first evidence of intracellular digestion of cell organelles (which they called autolysis after Christian de Duve). However Porter and Ashford wrongly interpreted their data that the structures were lysosomes being formed (ignoring the pre-existing organelles), lysosomes could not be cell organelles but part of cytoplasm such as mitochondria, and that hydrolytic enzymes were produced by microbodies (now called peroxisomes, which do not have any digestive function).[5] Inspired by this discovery, the term "autophagy" was invented by de Duve, the Nobel Prize-winning discoverer of lysosomes and peroxisomes. Unlike Porter and Ashford, de Duve conceived the term as a part of lysosomal function while describing the the role of glucagon as a major inducer of cell degradation in the liver. With his postdoctoral student Russell L. Peter, he subsequently established that lysosomes are indeed responsible for glucagon-induced autophagy.[6][7] This was the first time the fact that lysosomes are the sites of intracellular autophagy was established. He first publicly used the word at the first international symposium on lysosomes, the Ciba Foundation Symposium on Lysosomes held in London during 12-14 February 1963. He specifically introduced it while making a speech on "The Lysosome Concept" to explain the otherwise terminology "cytolysomes" introduced by Alex B. Novikoff. Source of the article published in description is Wikipedia. I am sharing their material. Copyright by original content developers. Link- http://en.wikipedia.org/wiki/Main_Page