Bioethics Blogs

Protein Links Gut Microbes, Biological Clocks, and Weight Gain

Caption: Lipids (red) inside mouse intestinal cells with and without NFIL3.
Credit: Lora V. Hooper, University of Texas Southwestern Medical Center, Dallas

The American epidemic of obesity is a major public health concern, and keeping off the extra pounds is a concern for many of us. Yet it can also be a real challenge for people who may eat normally but get their days and nights mixed up, including night-shift workers and those who regularly travel overseas. Why is that?

The most obvious reason is the odd hours throw a person’s 24-hour biological clock—and metabolism—out of sync. But an NIH-funded team of researchers has new evidence in mice to suggest the answer could go deeper to include the trillions of microbes that live in our guts—and, more specifically, the way they “talk” to intestinal cells. Their studies suggest that what gut microbes “say” influences the activity of a key clock-driven protein called NFIL3, which can set intestinal cells up to absorb and store more fat from the diet while operating at hours that might run counter to our fixed biological clocks.

NFIL3 is a transcription factor, a protein that switches certain genes on and off. Earlier studies had focused on its role in immune cells, but a team led by Lora Hooper at the University of Texas Southwestern Medical Center, Dallas, discovered that NFIL3 is also found in cells in the inner lining, or epithelium, of the mouse small intestine.

Intriguingly, as reported recently in the journal Science [1], they noticed that NFIL3 levels were much lower in the intestines of “germ-free” mice that don’t have any gut microbes.

The views, opinions and positions expressed by these authors and blogs are theirs and do not necessarily represent that of the Bioethics Research Library and Kennedy Institute of Ethics or Georgetown University.