 Autophagy. Why do we need it? This is Paul. Every day he reads his favorite newspaper, but over time a giant stack of paper collects in his house. Only the recycling truck can save him from drowning in yesterday's news. But what happens to his paper afterwards? Much of it is reconstituted for new uses in the cycle we call recycling. But long before we began recycling our trash, nature was following the same principle. Even the cells in our body recycle their trash. There, the cycle is called autophagy. Cells eliminate invading viruses and bacteria, but also harmful protein aggregates and old or damaged parts of the cell's nucleus that are no longer needed. The process of breaking these things down involves two liquid-filled structures inside the cell. The autophagyzoam collects the trash and transports it to the lysosome. The lysosome contains digestive enzymes that finally separate the cellular junk into its component parts. But don't worry, nothing goes to waste. These broken down parts are turned into new cell components that could be used again. This has many advantages. Our body's natural resources are conserved, we save energy and our cells' trash can never overflow. But sometimes the trash isn't disposed of correctly. This can cause diseases such as infections with certain forms of viral influenza, Alzheimer's or cancer. But how is autophagy controlled? Paul found the answer in one of his newspapers. The Japanese biologist Yoshinori Osumi was doing research about 25 years ago when he made a major discovery. He was investigating the genes of simple yeast cells. In various experiments he kept changing those genes in order to test the effect this would have on the cells' recycling process. Eventually he found 15 genes in the yeast that were responsible for different stages of the autophagy process. Then he was able to apply his finding to human cells which is why he received the 2016 Nobel Prize in Physiology or Medicine. There are still many puzzles and secrets about autophagy but scientists are working on decoding them. Paul is relieved to know how important his built-in recycling system is for keeping his cells healthy.