Health Watch

From the Desk of Contributing Editor Geoffrey Dow

Single virus gene may cause obesity

If obesity seems to be spreading like a virus, that could be because it is. We're now closer to understanding how adenovirus-36 (Ad-36), thought to be responsible for some cases of obesity, causes fat cells to grow.

Last year Nikhil Dhurandhar at Louisiana State University at Baton Rouge showed that Ad-36 causes precursor cells to differentiate into fat cells, and could promote obesity in humans and animals. Now he has shown that a single viral gene is responsible for triggering this process, meaning that one day it may be possible to treat "viral obesity" by altering the action of that gene.

Dhurandhar's team engineered stem cells from human fat to express a single gene from Ad-36, called E4 ORF-1. The cells were much more likely to differentiate into fat cells than those that did not express the gene. When they blocked expression of E4 ORF-1 in cells infected by Ad-36, the cells failed to differentiate into fat cells — proof that this gene is both necessary and sufficient for fat cell differentiation (International Journal of Obesity, DOI: 10.1038/sj.ijo.0803748). Researchers may someday be able to block E4 ORF-1 in humans to prevent Ad-36-induced obesity, he says.

The gene also makes cells more responsive to insulin, so drugs that mimic this part of the gene's action may also be useful in treating type 2 diabetes. Hopefully they'll find a way to tease out this part of the gene's action from the fat-promoting part.