How Cells ‘Eat ThemselveS

Ce] slnourb dydo not we Forever.b (keep dymg and the bod r recycles the con p nents to make new cc 5 Autophngy s a normal phys ologcaJ process t at deals wnh destruct on of ce 5 1n the body It work: more ken cellu at garbage col e mm and recycl ng serwce prowdtng a ph 510 0g cal method For detox heat on where the body's cc Is recycle and remove their Internal waste products It malnmms homeosms or normal Functlomng by proten dcgradatton and turnover of the destroyed cell organelles For new cell formation When the body 15 under SUGS such as dunng Fastmg the process of autophagy speeds up to raptdly prowde Fuel for energy and budding blocks for renewal of cellular components The concept of autophagy emerged during the 19605. when researchers first observed that the cell could destroy Its own contents by enclosmg It In membranes, forming sack-llke vestcles that were transported to a recycling compartment, called the lysosome, for degradation.

Although autophagy was teengmsed in the 1960’s, the mechanism and physlologm] relevance remained poorly undetsmod for deades ull YoshInOtt Ohsutnt of Tokyo Institute of Technology In Japan used baker's yeast to Identify genes essential For autophagy. He then went on to eluctdate the underlying mechanisms For autophagy in yeast and showed that stmtlar sophisticated machmcry is used m human cells to recycle components. The Nobel Prme for 2016 In Phystology or Medtcme has been awarded to Oshutm for his dtswvettcs of mcChanlsmS

For autophagy.

The story began in the m1d-I9SOS when scientism observed a new speciallscd CAM” compartment, called an organelle, gontamtng enzymes that digest Prom“! carbohydrates and hpids. This specnahsed compartment 15 referred to as a “Momma” and hmctlons as a worltsmuon for

degradauon of cellular consutuents. Soon after the discovery of the

lysosome. researchers found that portions

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of the WI pts I ate sc ucst red lnlO “dd“ M c I Pasm were :50 Ptesem me 1er o s an ms :1 ring not =11 d‘ CHE“ ugh“; cc 5 an the t a "ndanc:

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“6 dc“: opmtnt m the: m5 5 “at not Increased dtamat Gilly fo

structures contatnmg a small amount of cytoplasm and mll’OCl‘lOl‘ldl’la were observed In cells of' rat [udney dutmg hydtonephtosw (a condttton that typically occurs when the kidney swells due to the Fallute of normal dtatnage of unne from the kidney to the

A murastopw mug: qfa tel! thaw: bawpromm m a memérane bound mcihndzcared ivy nmw) merge: twtb another such mrmzmmg enzymes m aampbagy (Credtt: Knbmart Obmmt)

Rec ns ng that t e sgmqum had t e capa Ity to d gest FL,“ of the Intracc at c men: 13c Elan cyt 0g st and N be] wreak C tlstan de DUVC COIned the term ‘aut phagy "‘1 53 Heal“) extenswely dtscussed thls Wncep; m a tevtew at: de Publlshgd In 1966 In Annual Re-wm 0f P )molog)! It was $13: LLlach that autophagy m ght be a mechan Sm for coplng w1th metabohc mm In response to starvat on and that It rmght have roles In the pathogenes s ofdtsease

Desptte many 1nd1cat 0m phagy could be an Important process, :ts mechamsm and regulation were not understood. ptobaby because only a handful of Iabotatoncs Were working on the problem. As a result, “u 1990's. almost 30 years after dc Duve coined

the term autophagy, the process remained : biologtml entgma It was then that Yoshinon

Ohsuml, then an Asststant Professor atTokyo

Untvetstty, deCIded to study EUEOPhaW "5mg

the budding yeast Saccharomymt cerevtm

as a model system The first questton he

addressed was whether autophagy emu

In [his unicellular otgamsm. Ohsuml

had been active m vattous research areas, but upon statttng his own lab m 1988, he focused his efforts on protein degradaton In the ‘tmmale’, an organelle that corresponds to the lysosomc In human cells. Yeast cc Is are relatively easy to study and consequently they ate often used as a model for human cells. They are patttculatly useful for the identlhcatton of genes that are Important m complex cellular pathways.

The yeast vacuole ts the funcuonal equivalent of the mammahan lysosomc Ohsum: reasoned that, 1f autophagy emtcd in yeast, then mhtbttton of enzymes found m the vacuoles Would lead to the accumulation of engulfed cytopiasmtc components m the

that auto cellular