“Lipin regulates how the body stores and burns fat. Our findings suggest that differences in lipin levels may play a role in why some people are more prone to weight gain than others who consume the same calories,” said principal investigator Dr Karen Reue, a professor of medicine and human genetics at the David Geffen School of Medicine at UCLA and a researcher at the Veterans Affairs Greater Los Angeles Healthcare System.
In 2001, Reue’s laboratory was the first to isolate the lipin gene and link it to lipodystrophy, a wasting disorder in which the body is unable to produce fat. She also found that too little lipin prevented both genetic and diet-related obesity.
For this study, Reue and coauthor Dr Jack Phan tested whether too much lipin would produce the opposite effect. Their team developed animal models using two sets of specially bred mice. When fed a high-fat diet for six weeks, the mice with elevated lipin in their fat or muscles showed accelerated weight gain – double the amount of weight gained by the normal mice.
Although both sets of mice gained excessive weight, the researchers were surprised to see that the lipin affected fat tissue and muscles differently. While lipin in fat tissue influences the capacity of cells to store fat, lipin in muscle affects the rate at which the body expends energy and burns fat.
“When we increased lipin in the muscle, the cells burned carbohydrates before fat. When lipin is absent, however, the cells burn fat before carbohydrates,” explained Reue. “We saw a different effect when lipin acted on fat tissue. High levels of lipin promoted fat storage. Lipin deficiency prevented the cells from forming and storing fat.”
The study suggests that variations in lipin levels could determine a person’s tendency to gain weight by influencing how their body uses fat.
In an unexpected finding, the study also discovered that lipin levels helped the fat cells metabolize glucose more efficiently, leading to lower blood-sugar levels. The obese mice with excess lipin in their fat tissue demonstrated even lower blood-sugar levels than normal mice with regular levels of lipin. This could suggest potential for new therapies for diabetes.