Intestinal stem cells respond to food by supersizing the gut

October 27, 2011
These are cells in the adult fly midgut. The intestinal cells are outlined in red and have large blue nuclei. The stem cells are tiny and colored green (their nuclei are not visible). Credit: Lucy O'Brien and David Bilder, UC Berkeley

A new study from University of California, Berkeley, researchers demonstrates that adult stem cells can reshape our organs in response to changes in the body and the environment, a finding that could have implications for diabetes and obesity.

Current thinking has been that, once mature into , they sit quietly in our tissues, replacing cells that die or are injured but doing little else.

But in working with , the researchers found that intestinal responded to increased by producing more intestinal cells, expanding the size of the intestines as long as the food keeps flowing.

"When flies start to eat, the intestinal stem cells go into overdrive, and the gut expands," said UC Berkeley post-doctoral fellow Lucy O'Brien. "Four days later, the gut is four times bigger than before, but when food is taken away, the gut slims down."

Just as in humans and other mammals, O'Brien added, the fly secretes its own insulin. In flies, intestinal insulin seems to be the signal that makes stem cells "supersize the gut."

"Because of the many similarities between the fruit fly and the human, the discovery may hold a key to understanding how human organs adapt to environmental change," said David Bilder, UC-Berkeley associate professor of .

The research will be published in the Oct. 28 issue of the journal Cell.

Stem cells key to adaptability

Many tissues grow or shrink with usage, including muscle, liver and intestine. Human intestines, for example, regrow after portions have been surgically removed because of cancer or injury, and see their intestines shrink to one-third their normal size during winter.

"One strategy animals use to deal with environmental variability is to tune the workings of their to match the conditions at hand," O'Brien said. "How exactly this 'organ adaptation' happens, particularly in adult animals that are no longer growing, has long been a mystery."

Following the surprising discovery of stem cells in the intestines of fruit flies five years ago, O'Brien and Bilder decided to investigate the role of adult stem cells in normal intestinal growth in hopes of finding clues to their role in vertebrates like us.

"I looked at stained stem cells in the fruit fly intestine, and they are studded throughout like jewels. The tissues were so beautiful, I knew I had to study them," O'Brien said.

O'Brien, Bilder and their colleagues discovered that when fruit flies feed, their intestines secrete insulin locally, which stimulates intestinal stem cells to divide and produce more intestinal cells.

"The real surprise was that the fruit fly intestine is capable of secreting its own insulin," BIlder said. "This intestinal insulin spikes immediately after feeding and talks directly to stem cells, so the intestine controls its own adaptation."

Stem cells can divide either asymmetrically, producing one stem cell and one intestinal cell, or symmetrically, producing two stem cells. The team found that, in response to food, intestinal stem cells underwent symmetric division more frequently than asymmetric division, which had the effect of maintaining the proportion of stem cells to , and is a more efficient way of ramping up the total number of cells, O'Brien said.

"Adaptive resizing of the intestine makes sense from the standpoint of physiological fitness," she said. "Upkeep of the intestinal lining is metabolically expensive, consuming up to 30 percent of the body's energy resources. By minimizing intestinal size when food is scarce, and maximizing digestive capacity when food is abundant, adaptive intestinal resizing by stem cells helps animals survive in constantly changing environments."

Explore further: Study: Stem cells found in fruit fly gut

Related Stories

'Scrawny' gene keeps stem cells healthy

January 7, 2009

(PhysOrg.com) -- Stem cells are the body's primal cells, retaining the youthful ability to develop into more specialized types of cells over many cycles of cell division. How do they do it? Scientists at the Carnegie Institution ...

The making of an intestinal stem cell

March 5, 2009

Researchers have found the factor that makes the difference between a stem cell in the intestine and any other cell. The discovery reported in the March 6th issue of the journal Cell, a Cell Press publication, is an essential ...

Attacking bowel cancer on two fronts

March 31, 2011

Stem cells in the intestine, which when they mutate can lead to bowel cancers, might also be grown into transplant tissues to combat the effects of those same cancers, the UK National Stem Cell Network (UKNSCN) annual science ...

Recommended for you

Secrets of a heat-loving microbe unlocked

September 4, 2015

Scientists studying how a heat-loving microbe transfers its DNA from one generation to the next say it could further our understanding of an extraordinary superbug.

How nature punches back at giant viruses

September 4, 2015

(Phys.org)—What have viruses ever done for humans? The question is debatable, but given the prevalence of highly contagious, and sometimes life-threatening illnesses caused by viruses, it's fair to say that most people ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

jimbo92107
not rated yet Oct 27, 2011
Computers sure have a long way to go...

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.