1205 GMT November 19, 2019
When the scientists genetically blocked production of the worms' yolk lipoprotein, called ‘vitellogenin’ (VIT), the nematodes lived up to 40 percent longer, the study showed. Mice, humans and other mammals produce a directly analogous protein called ‘apolipoprotein B’ (apoB) and therapies have been developed to reduce apoB to prevent cardiovascular disease, Tech Times said.
The new research suggests that there might be a whole other benefit to reducing apoB. Data from the nematodes indicate that apoB's evolutionary cousin VIT prevents long life span by impairing the ability of cells to use and remodel fats for healthier purposes.
"That protein, which has an ortholog in humans, is a major decider of what happens to fat inside intestinal cells," said Louis Lapierre, assistant professor of molecular biology, cell biology and biochemistry at Brown University and senior author of the study in the journal Autophagy. "If you reduce the production of these lipoproteins you allow the fat to be reused in different ways."
Lipophagy is the name for the process of breaking down large quantities of built up fats and reusing them for other purposes. The new study showed that the longevity benefits associated with increased lipophagy are hindered by too much VIT.
Lapierre's team, including lab manager and co-lead author Nicole Seah, demonstrated the link directly. Some experiments, for example, showed that the life span benefits of blocking VIT didn't occur if autophagy was blocked in other ways. They also showed that VIT hinders a related process called lysosomal lipolysis, the endpoint of lipophagy which catalyzes fat breakdown.
In mice, the team connected this effect to another well-known model of increased longevity: Dietary restriction. Many studies have shown that animals that eat less, live longer. In this study, the researchers showed that calorie-restricted mice produced less apoB.
In nematodes, the normal purpose of VIT is thought to primarily involve the transport of fats from the intestine to the reproductive system to nourish eggs and aid in reproduction. Similarly in mammals, Lapierre said, a purpose of apoB is to transfer fats away from the intestine and liver toward other tissues where they can either be used or stored.