14 Sep
Many of us, especially the current or former graduate students among us, are addicted to our breakfast caffeinated beverage of choice. Mine is tea, but if I had to guess, I'd wager that the most popular option is coffee. We chug it down in the morning to get ready for our day, we sip it thoughtfully at work, and we seek it out in the wee hours when we should be sleeping but instead we're at the lab or at our desks, telling ourselves that we'll run just one more gel or write just one more page. The ritual of coffee (or tea!) is deeply ingrained in our daily lives for many of us, but aside from keeping us alert, what else does it do for us? A recent study suggests that certain polyphenolic compounds in tea and coffee may offer protective effects against type 2 diabetes mellitus (T2 diabetes) by interfering with the formation of amyloid fibrils in the pancreas. Wow, that sounds great, doesn't it? Another excuse to drink more of the stuff! But what the heck does it mean? In order to understand how this might work, we first need to understand some concepts. Specifically, what is an amyloid fibril, and what does it have to do with T2 diabetes?
Amyloids are deposits of proteins that have been folded in a specifically incorrect way (proteins must be folded properly in order to function properly). These misfolded proteins form aggregates (i.e., they clump together) that build up in tissues and cells, similar to the way that calcium deposits might build up in your pipes, for instance. You can see what this looks like in the photo to the left, which shows amyloid deposits (brown) of Abeta protein in the cerebral cortex. Amyloids tend to be associated with diseases such as Parkinson's and Alzheimer's disease in addition to T2 diabetes. The exact way that these protein deposits contribute to these diseases is unclear, but it is thought that their presence causes the tissues around them to be deformed, thus interfering with their ability to do their job. They may also cause cell death by interfering with the mitochondria, which are the organelles that supply cells with energy. In the case of T2 diabetes, the presence of amyloid fibrils in the pancreas is thought to kill the beta-cells that produce insulin. The amyloid fibrils, in this case, are made of a protein called human islet amyloid polypeptide (hIAPP, or amylin), which normally functions as an endocrine (i.e., hormone) that is released along with insulin from the beta-cells. Therefore, one way we can think about treating T2 diabetes is to stop hIAPP amyloid fibrils from forming in the first place.
