Featured Research

from universities, journals, and other organizations

Gene Oppositely Controlled By Dietary Protein, Sugar

Date:
April 11, 2008
Source:
Cell Press
Summary:
Researchers have discovered a gene in flies whose activity rises and falls depending upon the amount of protein and sugar in the insects' diets. The findings might shed light on the way the insects' bodies -- and perhaps those of humans too -- handle dietary extremes.

Researchers have discovered a gene in flies whose activity rises and falls depending upon the amount of protein and sugar in the insects' diets. The findings, reported in the April issue of Cell Metabolism, might shed light on the way the insects' bodies--and perhaps those of humans too--handle dietary extremes, including high-protein, low-carb diets like the Atkins, according to the researchers. These findings are also yielding new clues about the links between diet and life span.

Related Articles


The gene, which the researchers call tobi (short for target of brain insulin), encodes an evolutionarily conserved a-glucosidase enzyme that converts stored glycogen into glucose.

"This gene is activated by high protein and repressed by sugar," said Michael Pankratz of Forschungszentrum Karlsruhe in Germany, who is now at the Fritz Lipmann Institute. "The question is: Why would the body need such a mechanism for releasing glucose under specific dietary conditions?"

High-protein diets might hold one answer, Pankratz said. For instance, when people consume high-protein, low-carb diets, insulin is released, stimulating cells to take in sugar from the bloodstream. (Most people associate insulin with sugar, he said, but indeed insulin is also released in response to the amino acid building blocks of proteins.) Given that little to no sugar is coming in, this can lead to hypoglycemia, or low blood sugar. The body therefore needs a second mechanism to release glucose from glycogen. "We think this is what's happening [in the flies]," he said. "It's a sensitive mechanism for dealing with extreme dietary conditions."

In mammals, one of the most important systems for controlling metabolism consists of the antagonistic actions of insulin and glucagon, the researchers explained. Upon high sugar intake, insulin is secreted by cells in the pancreas to maintain steady blood sugar levels. When blood glucose is low, glucagon is secreted by other pancreatic cells, causing the release of glucose from glycogen breakdown. The antagonism between insulin and glucagon is not strict, the researchers noted, since amino acids boost both insulin and glucagon secretion.

Earlier studies also identified insulin- and glucagon-like peptides in Drosophila fruit flies, but questions remained about how those signals act.

In the new study, by analyzing changes in gene activity in flies lacking insulin-producing cells, the researchers were led to tobi. They further found that tobi levels increased when flies consumed a protein-rich yeast paste and decreased when the insects ate a sugary concoction. That pattern of tobi expression is reminiscent of the hormone glucagon in mammals, the researchers noted, suggesting that the gene may be controlled by an analogous hormone.

Earlier studies had shown that flies lacking insulin-producing cells (which also express lower tobi levels) live longer. Indeed, the researchers found that this was true--but only in flies fed the high-protein diet.

Exactly what role tobi might play in life span will be a subject of further study, Pankratz said.

"The current study indicates that proteins may have a greater effect than sugars on insulin signaling, and evidence is growing that quality and not only quantity of calories taken in has an influence on life span," the researchers said. "Therefore, teasing apart the relative contributions of dietary proteins and sugars in insulin signaling should prove insightful."

"What is novel and exciting in the work of [Pankratz and colleagues] is the combination of gene regulation studies, endocrinology, and physiology in a model genetic organism whose genome and gene regulatory linkages can be readily compared to the human genome," wrote Eric Rulifson of the University of California, San Francisco, in an accompanying commentary. "Given the accumulating parallels between the islet-like cells of Drosophila and the pancreatic islets of mammals, it would not be surprising if this homeostatic mechanism, and possibly others yet to be found, is evolutionarily conserved between flies and humans."

The researchers include Susanne Buch, Institute of Genetics, Forschungszentrum Karlsruhe, Karlsruhe, Germany, Leibniz Institute for Age Research, Fritz Lipmann Institute, Jena, Germany; Christoph Melcher, Institute of Genetics, Forschungszentrum Karlsruhe, Karlsruhe, Germany; Matthias Bauer, Institute of Genetics, Forschungszentrum Karlsruhe, Karlsruhe, Germany; Joerg Katzenberger, Institute of Genetics, Forschungszentrum Karlsruhe, Karlsruhe, Germany and Michael J. Pankratz, Institute of Genetics, Forschungszentrum Karlsruhe, Karlsruhe, Germany.


Story Source:

The above story is based on materials provided by Cell Press. Note: Materials may be edited for content and length.


Cite This Page:

Cell Press. "Gene Oppositely Controlled By Dietary Protein, Sugar." ScienceDaily. ScienceDaily, 11 April 2008. <www.sciencedaily.com/releases/2008/04/080408132154.htm>.
Cell Press. (2008, April 11). Gene Oppositely Controlled By Dietary Protein, Sugar. ScienceDaily. Retrieved March 31, 2015 from www.sciencedaily.com/releases/2008/04/080408132154.htm
Cell Press. "Gene Oppositely Controlled By Dietary Protein, Sugar." ScienceDaily. www.sciencedaily.com/releases/2008/04/080408132154.htm (accessed March 31, 2015).

Share This


More From ScienceDaily



More Health & Medicine News

Tuesday, March 31, 2015

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Soda, Salt and Sugar: The Next Generation of Taxes

Soda, Salt and Sugar: The Next Generation of Taxes

Washington Post (Mar. 30, 2015) — Denisa Livingston, a health advocate for the Dinι Community Advocacy Alliance, and the Post&apos;s Abby Phillip discuss efforts around the country to make unhealthy food choices hurt your wallet as much as your waistline. Video provided by Washington Post
Powered by NewsLook.com
UnitedHealth Buys Catamaran

UnitedHealth Buys Catamaran

Reuters - Business Video Online (Mar. 30, 2015) — The $12.8 billion merger will combine the U.S.&apos; third and fourth largest pharmacy benefit managers. Analysts say smaller PBMs could also merge. Fred Katayama reports. Video provided by Reuters
Powered by NewsLook.com
S. Leone in New Anti-Ebola Lockdown

S. Leone in New Anti-Ebola Lockdown

AFP (Mar. 28, 2015) — Sierra Leone imposed a three-day nationwide lockdown Friday for the second time in six months in a bid to prevent a resurgence of the deadly Ebola virus. Duration: 01:17 Video provided by AFP
Powered by NewsLook.com
These Popular Antibiotics Can Cause Permanent Nerve Damage

These Popular Antibiotics Can Cause Permanent Nerve Damage

Newsy (Mar. 27, 2015) — A popular class of antibiotic can leave patients in severe pain and even result in permanent nerve damage. Video provided by Newsy
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
 
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:  

Breaking News:

Strange & Offbeat Stories

 

Health & Medicine

Mind & Brain

Living & Well

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:  

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile iPhone Android Web
Follow Facebook Twitter Google+
Subscribe RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins