Featured Research

from universities, journals, and other organizations

Kinetochores prefer the 'silent' DNA sections of the chromosome

Date:
July 5, 2011
Source:
Max-Planck-Gesellschaft
Summary:
The protein complex responsible for the distribution of chromosomes during cell division is assembled in the transition regions between heterochromatin and euchromatin. The centromere is a specialized region of the chromosome, on which a protein complex known as the kinetochore is assembled. During cell division, the kinetochore provides a point of attachment for molecules of the cytoskeleton, thereby mediating the segregation of chromosomes to the two opposing cell poles. Scientists have investigated the factors that play an essential role in the development of the kinetochore. According to new findings, both the organization of the chromosomes and epigenetic marks determine the location where a kinetochore and, eventually, a centromere can form.

Heterochromatin borders are “hotspots” for the formation of new kinetochores outside the centromere: Antibody-staining of fixed chromosomes of Drosophila cells during cell division. The double green arrow indicates normal endogenous kinetochores, the white arrow indicates newly-formed ectopic kinetochores (green: centromere-specific histone; blue: DNA; red: euchromatin). Scale: 3 micrometres.
Credit: P. Heun, MPI for Immunobiology and Epigenetics

The protein complex responsible for the distribution of chromosomes during cell division is assembled in the transition regions between heterochromatin and euchromatin.

Related Articles


The centromere is a specialized region of the chromosome, on which a protein complex known as the kinetochore is assembled. During cell division, the kinetochore provides a point of attachment for molecules of the cytoskeleton, thereby mediating the segregation of chromosomes to the two opposing cell poles. Scientists from the Max Planck Institute of Immunobiology and Epigenetics and BIOSS in Freiburg have investigated the factors that play an essential role in the development of the kinetochore. According to their findings, both the organisation of the chromosomes and epigenetic marks determine the location where a kinetochore and, eventually, a centromere can form.

Centromeres are visible under the microscope as constrictions in the chromosomes. During cell division, the kinetochore, which is attached to the centromere, adheres to the microtubuli of the cytoskeleton and ensures that the chromosomes are divided equally between the two daughter cells. It was already known that cells of the brewer's yeast Saccharomyces cerevisiae, contain a very specific gene section of 125 base-pairs in length, which binds to the kinetochore complex and thereby enables the formation of a centromere.

However, other organisms do not appear to have a specific gene sequence which defines the location of the kinetochore formation. Instead, researchers suspect that the position of the centromere is regulated epigenetically with the help of the centromere-specific DNA packaging protein (histone) CENH3/CENP-A. Histone proteins, around which the thread-like DNA molecule is wrapped at regular intervals, influence the spatial arrangement of the DNA strand and, therefore also, the accessibility of genes and binding of other proteins, for example the kinetochore complex.

The Freiburg-based researchers have now succeeded in demonstrating that not only the centromere histone CENH3 but also other factors contribute to the formation of a functional kinetochore. Using a new research method, they induced the formation of the centromere-specific histone CENH3 in cells of the fruit fly Drosophila. Although the cells incorporated the protein into their chromosomes in many sites, the de novo assembly of ectopic kinetochores occurred not randomly but preferentially at the transition between gene-poor (heterochromatin) and gene-rich (euchromatin) sections, most often at the ends of the chromosomes, the telomeres.

It is possible that the transition regions between heterochromatin and euchromatin and the telomeres promote the formation of a kinetochore due to the absence of the typical heterochromatin and euchromatin proteins. In addition, very few genes are expressed and translated into proteins in these regions. Moreover, the chromatin turnover in these regions is very low, so that the kinetochore-specific histone can accumulate. "Therefore, in addition to the centromere-specific histones, the surroundings of the chromosome clearly play a crucial role in the formation of the kinetochore. Epigenetic histone marks thereby also influence where a kinetochore and, ultimately, a centromere can form," explains Patrick Heun from the Max Planck Institute of Immunobiology and Epigenetics.


Story Source:

The above story is based on materials provided by Max-Planck-Gesellschaft. Note: Materials may be edited for content and length.


Journal Reference:

  1. Agata M. Olszak, Dominic van Essen, Antσnio J. Pereira, Sarah Diehl, Thomas Manke, Helder Maiato, Simona Saccani, Patrick Heun. Heterochromatin boundaries are hotspots for de novo kinetochore formation. Nature Cell Biology, 2011; DOI: 10.1038/ncb2272

Cite This Page:

Max-Planck-Gesellschaft. "Kinetochores prefer the 'silent' DNA sections of the chromosome." ScienceDaily. ScienceDaily, 5 July 2011. <www.sciencedaily.com/releases/2011/07/110705122728.htm>.
Max-Planck-Gesellschaft. (2011, July 5). Kinetochores prefer the 'silent' DNA sections of the chromosome. ScienceDaily. Retrieved November 24, 2014 from www.sciencedaily.com/releases/2011/07/110705122728.htm
Max-Planck-Gesellschaft. "Kinetochores prefer the 'silent' DNA sections of the chromosome." ScienceDaily. www.sciencedaily.com/releases/2011/07/110705122728.htm (accessed November 24, 2014).

Share This


More From ScienceDaily



More Plants & Animals News

Monday, November 24, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Stray Dog Follows Adventure Racing Team for 6-Day Endurance Race

Stray Dog Follows Adventure Racing Team for 6-Day Endurance Race

Buzz60 (Nov. 24, 2014) — A Swedish Adventure racing team travels to try and win a world title, but comes home with something way better: a stray dog that joined the team for much of the grueling 430-mile race. Jen Markham has the story. Video provided by Buzz60
Powered by NewsLook.com
Red Panda Cubs Explore the Bratislava Zoo

Red Panda Cubs Explore the Bratislava Zoo

AFP (Nov. 24, 2014) — Four-month old Red Panda twins Pim and Pam still rely on their mother for breast milk at the Bratislava Zoo in Slovakia, but the precocious cubs have begun to branch out to solid foods, as well. Duration: 00:41 Video provided by AFP
Powered by NewsLook.com
Are Female Bosses More Likely To Be Depressed?

Are Female Bosses More Likely To Be Depressed?

Newsy (Nov. 24, 2014) — A new study links greater authority with increased depressive symptoms among women in the workplace. Video provided by Newsy
Powered by NewsLook.com
Winter Can Cause Depression — Here's How To Combat It

Winter Can Cause Depression — Here's How To Combat It

Newsy (Nov. 23, 2014) — Millions of American suffer from seasonal depression every year. It can lead to adverse health effects, but there are ways to ease symptoms. 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

 

Plants & Animals

Earth & Climate

Fossils & Ruins

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