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.

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 July 25, 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 July 25, 2014).

Share This




More Plants & Animals News

Friday, July 25, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

How to Make Single Serving Smoothies: Howdini Hacks

How to Make Single Serving Smoothies: Howdini Hacks

Howdini (July 24, 2014) — Smoothies are a great way to get in lots of healthy ingredients, plus they taste great! Howdini has a trick for making the perfect single-size smoothie that will save you time on cleanup too! All you need is a blender and a mason jar. Video provided by Howdini
Powered by NewsLook.com
Boy Attacked by Shark in Florida

Boy Attacked by Shark in Florida

Reuters - US Online Video (July 24, 2014) — An 8-year-old boy is bitten in the leg by a shark while vacationing at a Florida beach. Linda So reports. Video provided by Reuters
Powered by NewsLook.com
Goma Cheese Brings Whiff of New Hope to DRC

Goma Cheese Brings Whiff of New Hope to DRC

Reuters - Business Video Online (July 24, 2014) — The eastern region of the Democratic Republic of Congo, mainly known for conflict and instability, is an unlikely place for the production of fine cheese. But a farm in the village of Masisi, in North Kivu is slowly transforming perceptions of the area. Known simply as Goma cheese, the Congolese version of Dutch gouda has gained popularity through out the region. Ciara Sutton reports. Video provided by Reuters
Powered by NewsLook.com
Tyrannosaur Pack-Hunting Theory Aided By New Footprints

Tyrannosaur Pack-Hunting Theory Aided By New Footprints

Newsy (July 24, 2014) — A new study claims a set of prehistoric T-Rex footprints supports the theory that the giant predators hunted in packs instead of alone. 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:
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