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 29, 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 29, 2014).

Share This




More Plants & Animals 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
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
Asteroid's Timing Was 'Colossal Bad Luck' For The Dinosaurs

Asteroid's Timing Was 'Colossal Bad Luck' For The Dinosaurs

Newsy (July 28, 2014) — The asteroid that killed the dinosaurs struck at the worst time for them. A new study says that if it hit earlier or later, they might've survived. Video provided by Newsy
Powered by NewsLook.com
Raw: Sea Turtle Hatchlings Emerge from Nest

Raw: Sea Turtle Hatchlings Emerge from Nest

AP (July 27, 2014) — A live-streaming webcam catches loggerhead sea turtle hatchlings emerging from a nest in the Florida Keys. (July 27) 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