Featured Research

from universities, journals, and other organizations

New Clues To How Stem Cells Form

Date:
April 17, 2009
Source:
Emory University
Summary:
A study on the nematode C. elegans shows some of the first direct evidence of a process required for epigenetic reprogramming between generations -- a finding that could shed more light on the mechanisms of fertilization, stem-cell formation and cloning.

An Emory University study shows some of the first direct evidence of a process required for epigenetic reprogramming between generations – a finding that could shed more light on the mechanisms of fertilization, stem-cell formation and cloning. The journal Cell published the results of the study on the nematode C. elegans in its April 17 issue.

"We believe that we have demonstrated one of the processes that erases the information in a fertilized egg, so that the offspring can begin life with a clean slate," says David Katz, lead author of the study. Katz is a post-doctoral fellow in the lab of William Kelly, associate professor of biology at Emory and a co-author of the study.

"One of the most fundamental mysteries in biology is how a sperm and egg create a new organism. By looking at the process at the molecular level, we're gaining understanding of this basic question of life," Katz says.

When a sperm cell fertilizes an egg cell, the specialized programming of each parent cell must be erased, in order to form a zygote that can give rise to a new organism. The process by which these two differentiated cells return to a developmental ground state in the zygote – the ultimate stem cell – is little understood.

'An amazing phenotype'

The Emory researchers wanted to test the theory that removal of a particular histone protein modification involved in the packaging of DNA – dimethylation of histone H3 on lysine 4 – is involved in reprogramming the germ line.

They compared successive generations of a normal strain of C. elegans – a microscopic worm commonly used for studying cell differentiation – with a mutant strain. The mutants lacked an enzyme that test-tube experiments have previously shown appears to play an "erasing" role – demethylating histones to remove information from the packaging of DNA.

In the normal strain of the worms, the histone modification the Emory researchers had targeted was not passed on to the next generation, but in the mutant strain the modification continued through 30 generations, and each generation became progressively less fertile.

"That's an amazing phenotype," Katz says. "The organism gradually lost its ability to reproduce. We have shown that when this enzyme is missing, the worms can inherit the histone modification – not only from cell to cell, but from generation to generation."

When the researchers re-inserted the missing enzyme into the sterile generations of mutant worms, they were able to reverse the process: the worms no longer inherited the histone modification, and they regained fertility.

Showing inheritance of epigenetic event

For years, it's been accepted that histone proteins help coil six-foot strands of DNA into tight balls, compact enough to fit inside the nucleus of a cell. Histone modifications have also been known to correlate with gene expression. More recently, researchers have theorized that a chemical change in the histone packaging of DNA, known as an epigenetic event, can be passed on – just as genes themselves can be inherited.

"This study is one of the first demonstrations in a living organism that this theory may be true – that every generation can be affected by an epigenetic event," Kelly says.

"Our work provides some of the best, direct evidence that chemical modifications in the packaging of DNA can be inherited from cell to cell," Katz added. "That indicates that these chemical modifications are not just involved in packaging – they contain information."

Groundwork for stem-cell therapies

A better understanding of the role of histones, and the enzymes involved in their modification, could lead to therapies for everything from cancer to infertility. "Stem-cell therapies are an incredibly promising technology for treating any problem that has to do with defective cells," Katz says. "We're hoping that our work will help this technology to develop."

Additional authors on the Emory study were Matthew Edwards, a research specialist at Emory, and Valerie Reinke of Yale University School of Medicine.

Katz and his colleagues are now building on the results of the study, to see if a lack of the erasing enzyme shows a similar effect in mice.


Story Source:

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


Cite This Page:

Emory University. "New Clues To How Stem Cells Form." ScienceDaily. ScienceDaily, 17 April 2009. <www.sciencedaily.com/releases/2009/04/090416125205.htm>.
Emory University. (2009, April 17). New Clues To How Stem Cells Form. ScienceDaily. Retrieved July 29, 2014 from www.sciencedaily.com/releases/2009/04/090416125205.htm
Emory University. "New Clues To How Stem Cells Form." ScienceDaily. www.sciencedaily.com/releases/2009/04/090416125205.htm (accessed July 29, 2014).

Share This




More Health & Medicine News

Tuesday, July 29, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Deadly Ebola Virus Threatens West Africa

Deadly Ebola Virus Threatens West Africa

AP (July 28, 2014) West African nations and international health organizations are working to contain the largest Ebola outbreak in history. It's one of the deadliest diseases known to man, but the CDC says it's unlikely to spread in the U.S. (July 28) Video provided by AP
Powered by NewsLook.com
$15B Deal on Vets' Health Care Reached

$15B Deal on Vets' Health Care Reached

AP (July 28, 2014) A bipartisan deal to improve veterans health care would authorize at least $15 billion in emergency spending to fix a veterans program scandalized by long patient wait times and falsified records. (July 28) Video provided by AP
Powered by NewsLook.com
Two Americans Contract Ebola in Liberia

Two Americans Contract Ebola in Liberia

Reuters - US Online Video (July 28, 2014) Two American aid workers in Liberia test positive for Ebola while working to combat the deadliest outbreak of the virus ever. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Traditional African Dishes Teach Healthy Eating

Traditional African Dishes Teach Healthy Eating

AP (July 28, 2014) Classes are being offered nationwide to encourage African Americans to learn about cooking fresh foods based on traditional African cuisine. The program is trying to combat obesity, heart disease and other ailments often linked to diet. (July 28) Video provided by AP
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:
from the past week

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