Featured Research

from universities, journals, and other organizations

Discovery Of Protection Against Cell Division Failures

Date:
March 15, 2009
Source:
ETH Zurich
Summary:
Researchers have described the causes for division errors of human tissue cells and how the cells protect themselves against these.

This cell is having difficulties in cell division. A chromosome bridge remains between the newly formed cell nuclei. A component of the cell skeleton has been labelled green, and the cell nuclei and chromosome bridge are red. (Picture: the Gerlich group)
Credit: Image courtesy of ETH Zurich

ETH researchers have described the causes for division errors of human tissue cells and how the cells protect themselves against these.

The human body is made up of billions of cells which constantly divide, even in adults. This is how tissues are renewed and any damages repaired. Normal cell division follows a fixed pattern: the chromosomes in a cell are duplicated and then redistributed so that two identical chromosome clusters are generated. A cleavage furrow then ingresses between the two chromosome clusters, which then form distinct cell nuclei. The cleavage furrow deepens and finally completely separates the original cell into two daughter cells. Both contain their own cell nucleus.

However, Daniel Gerlich, professor at the Institute for Biochemistry at ETH Zόrich, and his group are interested in the cases when something goes wrong in the cell division process. Sometimes the cell begins to divide, forms two cell nuclei, but cannot complete the division process. In these cases, the cleavage furrow regresses and the cell does not divide. This creates a cell with two nuclei. These cells are called tetraploid cells and are thought to be precursors of cancer cells.

Chromosome bridges impede cell division

Gerlich’s group investigated the causes leading tetraploidization. Using special labelling techniques, they were able to observe the details of what went wrong in the division of living cells under an optical microscope. “We saw that in some dividing cells a connection containing chromosome material remained between the two nuclei”, Gerlich reports. These faults in cell division are called chromosome bridges. Until now, their effect on the cells was not clear. The group was able to show that chromosome bridges often caused tetraploidization. The undivided chromosome parts appear to impede the final separation of the two daughter cells.

However, not every chromosome bridge led to a tetraploid cell. Observation over long periods of time showed that many of the partially divided cells with chromosome bridges later completed cell division. On closer investigation, however, the researchers discovered that the process was slower compared to cells without chromosome bridges. “We concluded that there must be a mechanism which helps the cell to divide successfully, even if it takes slightly longer”, Gerlich explains.

Aurora B delays cell division until chromosome bridges resolve

The researchers identified the already known enzyme Aurora B as an important player in the process. “We noticed that Aurora B stayed active for longer in cells with chromosome bridges”, Gerlich reveals. When Aurora B was active, the daughter cells did not fully separate. The cellular canal containing the chromosome bridge remained open at first, giving the chromosomes enough time to separate. As soon as this was completed, Aurora B was inactivated. This was then the signal for the two daughter cells to fully separate.

When the researchers artificially switched off Aurora B in the experiment, cell division failed as the chromosome bridges formed a barrier. As a result, the cleavage furrow regressed. The daughter cells were not separated and the cell nuclei remained together in the original cell, thus making it tetraploid.

“The experiments suggest that Aurora B responds to non-separated chromosomes and is part of a protective mechanism that ensures that the final step of cell division is only initiated when all chromosomes have been fully separated”, Gerlich explains. Aurora B therefore helps most cells to divide perfectly, even if they have initial difficulties.

Breakthrough thanks to new methods

In order for the researchers to observe the cell division process in detail, they first had to make it visible. They developed their own labelling methods and adapted existing ones. “The use of fluorescent protein markers was key to identify fine structures such as chromosome bridges under an optical microscope, and to follow their development”, Gerlich states.

The researchers used automated microscopic video recordings to observe the division of thousands of cells for up to 100 hours. As such data require specialized tools for appropriate analysis, part of the research group works on the development of new computational image processing methods. In order to handle the huge amounts of data generated, the group will soon have to upgrade their storage capacity well into the realm of terabytes.


Story Source:

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


Journal Reference:

  1. Steigemann et al. Aurora B-Mediated Abscission Checkpoint Protects against Tetraploidization. Cell, 2009; 136 (3): 473 DOI: 10.1016/j.cell.2008.12.020

Cite This Page:

ETH Zurich. "Discovery Of Protection Against Cell Division Failures." ScienceDaily. ScienceDaily, 15 March 2009. <www.sciencedaily.com/releases/2009/03/090310122832.htm>.
ETH Zurich. (2009, March 15). Discovery Of Protection Against Cell Division Failures. ScienceDaily. Retrieved July 31, 2014 from www.sciencedaily.com/releases/2009/03/090310122832.htm
ETH Zurich. "Discovery Of Protection Against Cell Division Failures." ScienceDaily. www.sciencedaily.com/releases/2009/03/090310122832.htm (accessed July 31, 2014).

Share This




More Plants & Animals News

Thursday, July 31, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Visitors Feel Part of the Pack at Wolf Preserve

Visitors Feel Part of the Pack at Wolf Preserve

AP (July 31, 2014) — Seacrest Wolf Preserve on the northern Florida panhandle allows more than 10,000 visitors each year to get up close and personal with Arctic and British Columbian Wolves. (July 31) Video provided by AP
Powered by NewsLook.com
Florida Panther Rebound Upsets Ranchers

Florida Panther Rebound Upsets Ranchers

AP (July 31, 2014) — With Florida's panther population rebounding, some ranchers complain the protected predators are once again killing their calves. (July 31) Video provided by AP
Powered by NewsLook.com
Dangerous Bacteria Kills One in Florida

Dangerous Bacteria Kills One in Florida

AP (July 31, 2014) — Sarasota County, Florida health officials have issued a warning against eating raw oysters and exposing open wounds to coastal and inland waters after a dangerous bacteria killed one person and made another sick. (July 31) Video provided by AP
Powered by NewsLook.com
Raw: Thousands Flocking to German Crop Circle

Raw: Thousands Flocking to German Crop Circle

AP (July 30, 2014) — Thousands of people are trekking to a Bavarian farmer's field to check out a mysterious set of crop circles. (July 30) 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