Professor Benjamin Bickman (2:08)
Welcome to the Metabolic Classroom Podcast. I'm Ben Bickman. Thanks for letting me be your guest professor for the next few minutes. Don't worry about any pop quizzes. I'm here to simply make the science of metabolism clear, practical and engaging. Welcome to the Metabolic Classroom. I'm Professor Benjamin Bickman, a biomedical scientist and professor of cell biology. If you've never heard of plasmologens before, don't worry, you are in good company. These are special fats found in the membranes of our cells, every cell, but particularly relevant and enriched in places like the brain, the heart and nerves. They're not your ridge lipids, though. They help cells stay flexible because being too rigid is not good for a cell. They also protect against damage, as we'll get into in a moment, and even support energy production by facilitating the work of the mitochondria. By the end of this mini lecture, you'll understand what they are, why they matter for metabolism especially, and especially how they tie into a few subtopics that I'm going to focus on. Fat cells, mitochondrial function and insulin signaling, and even, of course, how your diet can influence some of this. Now, we're going to cover it all thoroughly, so make sure you settle in and take some notes if you need to. But let's get started by describing what plasmologens even are. As I noted, they are a type of fat, and they form some of the building blocks of our membranes or the structure of our membranes in our cells. Now, unlike regular fats, they have a unique structure, very unique compared to any of the other fats, and it makes them extra flexible and it does offer some protective roles as we'll get to in a moment, particularly with oxidative stress. Now, they are found all over the body, like I said, but especially these high demand tissues like the brain and the heart, and muscle cells, immune cells, cells that can have a potentially very large metabolic demand, are particularly enriched with plasmologens. For example, in the heart, plasmologens make up a big chunk of the fats that are in the membranes of these cardiomyocytes or the heart cells, and even more so in nerves, which are already covered with fat to help them function. The process of creating plasmologens begins in an organelle, a specific organelle or part of the cell called peroxisomes. Now, peroxisomes are interesting because they actually work kind of in concert with the mitochondria when it comes to breaking down fat. Although the peroxisomes do more than just that, so too do the mitochondria. But when we typically think about burning fat or breaking down fat through beta oxidation, we think of the mitochondria but some fats are actually too big for the mitochondria. Fats that are sometimes just referred to as very long chain fats. Well, that's where the peroxisome comes in. It's sort of a big brother to the mitochondria in that regard. So the peroxisomes can break down fats. That's also where these fats are built. So within the peroxisome, other cell parts can. Peroxisomes will start it. And then with the work of other parts of the cells, they add the finishing touches to the final lipids that are going to be called plasmologens. It is a fairly complex process, which isn't surprising when it comes to lipid biochemistry. It often is. And suffice it to say, if something goes wrong with plasmologen synthesis, if we can't make enough, there are consequences. There are even some genetic anomalies that have to do with making the cells less capable of producing plasmologens. There are consequences. For now know that plasmologens are not just fats sitting around being lazy. They are very involved in keeping cells functioning. Well, now let's talk about some of those broader functions. One thing I've already mentioned is that the plasmologians help keep cell membranes fluid. Now what do I mean by that? I mean that it helps the cell actually have some dynamic aspect to it, which you might think of some cells like muscle cells. Why would a muscle cell need to be dynamic? Well, it's not going to have the conformation demands that say a red blood cell has. A red blood cell, which also has plasmologens as it's flowing through the bloodstream, needs to be able to undergo tremendous conformational changes to squeeze through various parts of the cardiovascular system into sinuses and things, for example. Well, muscle cells don't have to do that, but muscle cells still have to be able to shift. It's almost like as much as the shape of the muscle cell isn't undergoing the dynamic shifts like a red blood cell is, it's landscape or its surface is almost like an ocean in that there are things moving around on it. No cell is ever rigid and firmly set. So when I say that plasmologens help keep cell membranes fluid, that's what I mean. It helps proteins move around, including things like the insulin receptor, as we'll come to, and that has to happen. We have to allow these proteins to shift around in order for the cell to respond to and then propagate or carry on signals like coordinating immune responses, responding to hormone signals or nerve impulses. Plasmologens also act as antioxidants, which can then soak up harmful molecules that we call reactive oxygen species, ROS or ROS that can get produced during just the normal course of metabolism. These ROS can absolutely damage cells. They can undergo force molecules like other lipids, proteins or aspects of the mitochondria to undergo this harmful oxidative damage. So in that sense, plasmologens act like a little bit of a shield protecting the cell. Now, let me expand on that just a bit because it is, it is an important part of plasmologens. So they do reduce oxidative stress and they do so by acting as a, a sacrificial shield in cell membranes. What is so unique about plasmologians is that they have a particular biochemical bond called a vinyl ether bond. That vinyl ether bond is highly reactive to ros, to oxidative stress. And so this is then going to. Whereas you'd have an oxidative stress molecule potentially bind to a protein or to DNA and damage it. When the ROS interacts with plasmologens, the vinyl ether bond can absorb that hit, then it in turn will break down. So it, it does, it is a sacrifice. You lose the, the plasmology in the process, but it's built to do that. It's better for a plasmology to take that hit and fall rather than, say, DNA. The antioxidant role absolutely is essential in helping the cell maintain normal balance of, of redox status. And again, remember where plasmologians are particularly enriched, like the brain and the heart. Gosh, we need those tissues to be working well. Thankfully, the plasmologians are there to ensure that oxidative stress isn't going too far. Now, as I noted, they're also involved in cell signaling and we are going to revisit this in just a bit when I get to insulin signaling. But that does mean, once again, that when broken down, plasmologians can release molecules that help control inflammation and cell growth. Plus they play a role in even very special processes like sperm, egg fusion or even the formation of muscle cells. Now, obviously, there's a lot I could get into when it comes to plasmologens because they play such an important role in biology. But what I want to focus on, of course, is the metabolic parts of, of plasmologens. So let's focus more on metabolism and let's start with a very kind of general overview. Plasmologens are key players in many metabolic reactions, including balancing the nature of our fat cells. And when plasmologin levels are reduced, we have metabolic consequences like an increased risk of type 2 diabetes and metabolic syndrome and heart disease. Low levels of plasmologens can also enhance inflammation and oxidative stress because they're not there to help balance those things out in. In instances, like I noted, where we have rare genetic disorders of an inability to produce sufficient plasmologens, it can be catastrophic, you know, very, very lethal and, and compromise health considerably. We just have, especially when it comes to oxidative stress, we lose this significant protector. All right, now let's really get into the fat cells now. Now, fat cells, or adipocytes, are more than just storage depots for extra calories. We've talked before abundantly about how fat cells are so involved in hormone reactions. But fat cells are very dynamic. The fat tissue is a dynamic organ. Fat cells are dynamic cells that, yes, they help regulate energy balance to ensure that we don't starve to death every time we fast for a bit. They also are important fat cells are when it comes to fertility and insulin sensitivity and the production of many relevant hormones. Plasmologens are key components of fat cell membranes, and they play a role in fascinating, a fascinating role in shaping how these cells function in particular, especially when it comes to transforming slow fat, if you will, into fast fat tissue. Now, this is something we've discussed before, so it'll sound familiar to you. But briefly, white fat and brown fat are two types of adipose tissue with very different jobs in the body. White fat found in places like your belly or your thighs, that's mostly your subcutaneous fat that you can pinch and jiggle, but also your visceral fat, the fat that is tucked deeper within your abdominal cavity. But white fat acts like you expect fat to act like. It has a very low metabolic rate and is very good at storing extra fat. Brown fat, on the other hand, is a metabolic, busy body. It is packed with mitochondria, which gives it its darker color, or why we call it brown. And these mitochondria are themselves unique because they are designed to really burn a lot of energy. This is because of the process of uncoupling, again, something we've discussed abundantly in the past. So while white fat stores energy, brown fat burns it. And some white fat can transform into a beige version that acts more like brown fat, revving up metabolism and here's the cool part. Plasmologens can help turn white fat into brown or beige fat. So it's taking a low metabolic rate fat and turning it into a very high metabolic rate fat. By increasing this process called thermogenesis, or the fat cell burning energy just for the sake of creating heat. The browning effect is like flipping a metabolic switch, helping the body just burn more fat. It increases metabolic rate. Studies in preclinical work actually show that boosting plasmologens reduces weight gain by by ramping up this heat producing activity. The thermogenesis mimicking what happens when you're exposed to cold or exercising. It is in a way like a natural fat burning boost and again, paradoxically happening in the fat cell itself. When you're a forward thinker, you don't just bring your a game, you bring your AI game. Workday is the AI platform that transforms the way you manage your people, money and agents so you can transform tomorrow Workday, moving business forever forward. Ready to order? Yes.