Featured Research

from universities, journals, and other organizations

Maintaining balance: Blood progenitor cells receive signals from niche cells and the daughter blood cells they create

Date:
January 9, 2012
Source:
University of California - Los Angeles Health Sciences
Summary:
Maintaining balance is crucial. In Drosophila, the common fruit fly, the creation and maintenance of the blood supply requires such balance. Stem cell scientists have now uncovered that two-way signaling from two different sets of cells is necessary for that balance, both to ensure enough blood cells are made to respond to injury and infection and that the blood progenitor cell population remains available for future needs.

Maintaining balance is crucial. In Drosophila, the common fruit fly, the creation and maintenance of the blood supply requires such balance.

UCLA stem cell scientists have now uncovered that two-way signaling from two different sets of cells is necessary for that balance, both to ensure enough blood cells are made to respond to injury and infection and that the blood progenitor cell population remains available for future needs.

The stem cell-like blood progenitor cells -- which contribute to the cells of the adult fruit fly's blood supply -- receive signals from cells that live in a nearby safe zone, or niche. These signals keep the progenitors in the same stem cell-like state so, when needed, they can begin differentiating into blood cells.

And in a new discovery, the UCLA stem cell scientists found that the blood progenitor cells receive critical signals back from the daughter blood cells they create, telling the progenitor cells when enough blood cells have been made and it's time to stop differentiating.

The new discovery of the "back talk" from the daughter blood cells appears Dec. 23, 2011 in the peer-reviewed journal Cell.

"The cells in the niche provide a safe environment to support blood progenitor cells," said study co-senior author Dr. Julian A. Martinez-Agosto, an assistant professor of human genetics and pediatrics and a researcher with the Eli and Edythe Broad Center of Regenerative Medicine and Stem Cell Research at UCLA. "When the blood progenitor cells receive signals from the niche cells it creates an environment for those cells to maintain their potential and not differentiate."

Previous studies have shown that when you remove the niche cells, the blood progenitor cells differentiate unchecked. Ultimately, the fruit fly runs out of blood progenitor cells and is not able to make new blood cells to mount an immune response to infection or injury, Martinez-Agosto said.

The new findings by Martinez-Agosto and study co-senior author Utpal Banerjee, a Broad center researcher and the Irving and Jean Stone Professor and chairman of molecular, cell and developmental biology in Life Sciences, identified additional signals not coming from the niche cells. The new signals were coming from the daughter blood cells the progenitors were making, a surprising discovery, Banerjee said.

Martinez-Agosto and Banerjee noted in the four-year study that once the progenitors cells had begun differentiating and the blood cells they were creating became mature, the progenitors became very quiescent, or quiet, and did not multiply. They theorized that there must be a signal coming from the daughter cells that told the progenitors to stop multiplying and differentiating.

"It was a very surprising finding, because there was no reason to suspect that the differentiating cells had any role at all in the process," Banerjee said. "It's always been the paradigm in stem cell biology that all that was needed was the signaling from the niche cells to maintain the progenitor population. Now, we've shown that you also need the signals from the daughter cells to help maintain the progenitor cell population."

The signaling from the niche cells that maintains the progenitor population is called Hedgehog. In this study, the scientists showed that the daughter cells are sending back a signal to the progenitors that is mediated by Adenosine deaminase growth factor A (Adgf-A). The signal regulates extracellular levels of adenosine, which opposes or counters the effects of Hedgehog signaling.

"We've shown that adenosine as a molecule is really important for regulating the proliferation of progenitor cells in blood. And it requires a delicate balance -- just enough signaling to give you more blood cells, but not so much that all the progenitor cells are lost," Martinez-Agosto said. "Maybe other progenitors or stem cells are using the same signaling to determine when to differentiate or not."

The team used the fruit fly because it is a very accessible model organism in which genes can be easily manipulated and their effects on cells monitored, Martinez-Agosto said. They dissected the fly lymph gland, where blood cells are made, and used green florescence to label progenitors and their daughter cells to determine when they were differentiating.

Going forward, the team will try to understand if the progenitor cells can sense the adenosine in their microenvironment under stress and injury conditions and how cell division biologically counters the niche signaling to promote formation of blood cells.

The study was funded in part by the National Heart, Lung and Blood Institute.

"Our findings reveal signals arising from differentiating cells that are required for maintaining progenitor cell quiescence and that function with the niche-derived signal in maintaining the progenitor state," the study states. "Similar homeostatic mechanisms are likely to be utilized in other systems that maintain relatively large numbers of progenitors that are not all in direct contact with the cells of the niche."


Story Source:

The above story is based on materials provided by University of California - Los Angeles Health Sciences. Note: Materials may be edited for content and length.


Journal Reference:

  1. BamaCharan Mondal, Tina Mukherjee, Lolitika Mandal, CoryJ. Evans, SergeyA. Sinenko, JulianA. Martinez-Agosto, Utpal Banerjee. Interaction between Differentiating Cell- and Niche-Derived Signals in Hematopoietic Progenitor Maintenance. Cell, 2011; 147 (7): 1589 DOI: 10.1016/j.cell.2011.11.041

Cite This Page:

University of California - Los Angeles Health Sciences. "Maintaining balance: Blood progenitor cells receive signals from niche cells and the daughter blood cells they create." ScienceDaily. ScienceDaily, 9 January 2012. <www.sciencedaily.com/releases/2011/12/111222133338.htm>.
University of California - Los Angeles Health Sciences. (2012, January 9). Maintaining balance: Blood progenitor cells receive signals from niche cells and the daughter blood cells they create. ScienceDaily. Retrieved October 2, 2014 from www.sciencedaily.com/releases/2011/12/111222133338.htm
University of California - Los Angeles Health Sciences. "Maintaining balance: Blood progenitor cells receive signals from niche cells and the daughter blood cells they create." ScienceDaily. www.sciencedaily.com/releases/2011/12/111222133338.htm (accessed October 2, 2014).

Share This



More Health & Medicine News

Thursday, October 2, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Pregnancy Spacing Could Have Big Impact On Autism Risks

Pregnancy Spacing Could Have Big Impact On Autism Risks

Newsy (Oct. 1, 2014) A new study says children born less than one year and more than five years after a sibling can have an increased risk for autism. Video provided by Newsy
Powered by NewsLook.com
Robotic Hair Restoration

Robotic Hair Restoration

Ivanhoe (Oct. 1, 2014) A new robotic procedure is changing the way we transplant hair. The ARTAS robot leaves no linear scarring and provides more natural results. Video provided by Ivanhoe
Powered by NewsLook.com
Insertable Cardiac Monitor

Insertable Cardiac Monitor

Ivanhoe (Oct. 1, 2014) A heart monitor the size of a paperclip that can save your life. The “Reveal Linq” allows a doctor to monitor patients with A-Fib on a continuous basis for up to 3 years! Video provided by Ivanhoe
Powered by NewsLook.com
Attacking Superbugs

Attacking Superbugs

Ivanhoe (Oct. 1, 2014) Two weapons hospitals can use to attack superbugs. Scientists in Ireland created a new gel resistant to superbugs, and a robot that can disinfect a room in minutes. Video provided by Ivanhoe
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