Fat people live longer than skinny ones
According to the results obtained by researchers from Michigan State University, working under the guidance of Dr. Min-Hao Kuo, cells with a high fat content live longer than "lean" cells. These data can clarify the so-called "obesity paradox", which consists in the fact that overweight people have the lowest mortality rate from all causes, while for slim people this indicator, oddly enough, is comparable to the indicator for people with mild forms of obesity.
In experiments on yeast, which are an excellent model for studying various biological processes and mechanisms, the authors for the first time demonstrated a positive correlation between the content of triglycerides in a cell and its lifespan.
Triglyceride is a part of all eukaryotic cells, which include cells of animals, plants and fungi. The ability of this lipid to store excess energy, provide thermal insulation and accumulate in response to the effects of various stressors is well known to specialists. However, its effect on life expectancy turned out to be a complete surprise for the authors.
As part of their research, they used genetic approaches to manipulate the ability of cells to produce and break down triglyceride. Using sophisticated analysis methods, they demonstrated the ability of this compound to preserve the life of yeast cells by triggering a mechanism that is generally independent of other life-regulating signaling pathways that are universal for yeast and humans.
First, scientists removed triglyceride lipases from yeast cells – enzymes that break down the molecules of this lipid into small molecules used by the cell for various purposes, including the release of energy. The inability to utilize triglycerides led to an increase in fat deposits inside such cells. In addition, the researchers enhanced the production of lipids by increasing the activity of the enzyme that synthesizes triglyceride.
In both cases, both by blocking the breakdown of triglyceride and by increasing its production, yeast cells accumulated more fat deposits and had a longer lifespan. On the contrary, cells deprived of the ability to synthesize triglyceride were "thin" and died earlier. Overexpression of triglyceride lipase in yeast cells led to active breakdown of triglyceride, which also shortened their lifespan.
An interesting fact is that the "fat" long-lived cells obtained in various ways did not suffer from obvious violations of the growth process. They actively reproduced, produced a large number of offspring and demonstrated a normal level of resistance to various environmental stressors.
On the other hand, other well-known methods of increasing life expectancy, such as a low-calorie diet and the removal of genes that play a key role in assessing nutrient reserves, often lead to slow cell growth and a decrease in their resistance to environmental stresses.
The authors suggest that the phenomenon they have identified extends to humans, but this hypothesis requires confirmation. They hope that the data they have obtained will launch a new wave of research, the results of which will eventually lead to significant medical advances.
Article by Witawas Handee et al. An Energy-Independent Pro-longevity Function of Triacylglycerol in Yeast is published in the journal PLOS Genetics.