Featured Research

from universities, journals, and other organizations

Epigenetics: Protein linked to leukemia 'bookmarks' highly active genes during cell division

Date:
January 7, 2010
Source:
Cold Spring Harbor Laboratory
Summary:
Scientists have discovered how some epigenetic instructions get stably transferred from one generation of cells to the next. They report that newly formed cells learn which genes need to become highly active right away thanks to a helpful protein that "bookmarks" these genes during the division of their parent cell.

Each cell inherits genes from its parent as well as epigenetic information -- what amounts to an instruction manual that specifies which genes should be activated or "expressed," when and to what level. Cold Spring Harbor Laboratory (CSHL) scientist Chris Vakoc, M.D., Ph.D., and his team have now discovered how some of these epigenetic instructions get stably transferred from one generation of cells to the next.

The scientists report that newly formed cells inherit the knowledge of which genes need to become highly active right away thanks to a helpful protein that "bookmarks" these genes during the division of their parent cell. Their findings appear in the December 24th issue of Molecular Cell.

The bookmarking protein, called Mixed Lineage Leukemia or MLL, is notorious for triggering leukemia when the gene that encodes it becomes mutated. MLL mutations are among the most common genetic aberrations in leukemia, occurring in about 10% of leukemia cases.

"We now have a clearer picture of what MLL normally does in healthy cells to help gene expression information to travel from parent cells to daughter cells," said Vakoc. "These findings may help us understand how mutated MLL subverts inheritance mechanisms in leukemic cells."

During cell division or "mitosis," all gene activity is temporarily shut down. The dividing cell's chromosomes -- the X-shaped coils of DNA -- condense into tight clumps and expel most proteins that cling to DNA to maintain gene expression.

Vakoc's team was surprised to find, however, that unlike other chromosome-bound molecules, the MLL protein stays tethered to chromosomes during mitosis. Genome-wide surveys that compared MLL's chromosomal binding sites before and during division -- the first comparison of its kind -- revealed a second twist.

During division, the scientists found, MLL abandoned some of the genes that it was previously shackled to. Instead, for the duration of mitosis, MLL shifted to a new set of genes. This set, the team discovered, constitutes all the genes that were the most highly active before division triggered a blackout of all gene activity.

Such genes face the challenge of quickly reactivating to their previous high levels after division ends. "By seeking out and bookmarking this cohort of highly-expressed genes during division, MLL delivers a post-mitotic kick that helps turn genes back on," explains Vakoc. In support of this idea, his team found that when MLL was depleted, the reactivation of these genes was delayed and they "kicked" on more slowly. By staying tethered to these genes, MLL provides a beacon to which other proteins can home to, thereby jump-starting gene activity.

Vakoc is now exploring how the mutations that increase the activity of MLL in leukemia affects the gene reactivation pattern in new cells and how this might contribute to the abnormal cell proliferation and differentiation seen in leukemia.


Story Source:

The above story is based on materials provided by Cold Spring Harbor Laboratory. Note: Materials may be edited for content and length.


Journal Reference:

  1. Gerd A. Blobel, Stephan Kadauke, Eric Wang, Alan W. Lau, Johannes Zuber, Margaret M. Chou, and Christopher R. Vakoc. A Recond Pattern of MLL Occupancy within Mitotic Chromatin Promotes Rapid Transcriptional Reactivation Following Mitotic Exit. Molecular Cell, December 24, 2009 DOI: 10.1016/j.molcel.2009.12.001

Cite This Page:

Cold Spring Harbor Laboratory. "Epigenetics: Protein linked to leukemia 'bookmarks' highly active genes during cell division." ScienceDaily. ScienceDaily, 7 January 2010. <www.sciencedaily.com/releases/2010/01/100105150652.htm>.
Cold Spring Harbor Laboratory. (2010, January 7). Epigenetics: Protein linked to leukemia 'bookmarks' highly active genes during cell division. ScienceDaily. Retrieved September 19, 2014 from www.sciencedaily.com/releases/2010/01/100105150652.htm
Cold Spring Harbor Laboratory. "Epigenetics: Protein linked to leukemia 'bookmarks' highly active genes during cell division." ScienceDaily. www.sciencedaily.com/releases/2010/01/100105150652.htm (accessed September 19, 2014).

Share This



More Plants & Animals News

Friday, September 19, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Chocolate Museum Opens in Brussels

Chocolate Museum Opens in Brussels

AFP (Sep. 19, 2014) Considered a "national heritage" in Belgium, chocolate now has a new museum in Brussels. In a former chocolate factory, visitors to the permanent exhibition spaces, workshops and tastings can discover derivatives of the cocoa bean. Duration: 01:00 Video provided by AFP
Powered by NewsLook.com
Could Grief Affect The Immune Systems Of Senior Citizens?

Could Grief Affect The Immune Systems Of Senior Citizens?

Newsy (Sep. 19, 2014) The study found elderly people are much more likely to become susceptible to infection than younger adults going though a similar situation. Video provided by Newsy
Powered by NewsLook.com
Jury Delivers Verdict in Salmonella Trial

Jury Delivers Verdict in Salmonella Trial

AP (Sep. 19, 2014) A federal jury has convicted three people in connection with an outbreak of salmonella poisoning five years ago that sickened hundreds of people and was linked to a number of deaths. (Sept. 19) Video provided by AP
Powered by NewsLook.com
Raw: Elephant Undergoes Surgery in Tbilisi Zoo

Raw: Elephant Undergoes Surgery in Tbilisi Zoo

AP (Sep. 18, 2014) Grand the elephant has successfully undergone surgery to remove a portion of infected tusk at Tbilisi Zoo in Georgia. British veterinary surgeons used an electric drill to extract the infected piece. (Sept. 18) 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