Navigation Links
Chromosome 'anchors' organize DNA during cell division
Date:12/20/2012

LA JOLLA, CA----For humans to grow and to replace and heal damaged tissues, the body's cells must continually reproduce, a process known as "cell division," by which one cell becomes two, two become four, and so on. A key question of biomedical research is how chromosomes, which are duplicated during cell division so that each daughter cell receives an exact copy of a person's genome, are arranged during this process.

Now, scientists at the Salk Institute have discovered a new characteristic of human cell division that may help explain how our DNA is organized in the nucleus as cells reproduce. They found that telomeres, molecular caps that protect the ends of the chromosomes, move to the outer edge of the cell's nucleus after they have been duplicated.

While the implications of this spatial reorganization of telomeres are not yet clear, the findings may shed light on how our genes are regulated and how gene expression programs are altered during cell division, an important step in understanding aging and diseases that stem from genetic mutations, such as cancer.

"What we discovered is that telomeres not only protect our chromosomes, they also help organize our genetic material in the nucleus," says Jan Karlseder, a professor in Salk's Molecular and Cell Biology Laboratory and the Donald and Darlene Shiley Chair. "This is important, because the three-dimensional position of DNA in the nucleus influences gene expression profiles and how the genome morphs over time."

Telomeres, a combination of proteins and DNA, are crucial in DNA replication, tumor suppression and aging. Every time a primary human cell divides, its telomeres get shorter, until critically short telomeres lead cells to self-destruct. Much of Karlseder's research has focused on understanding telomere dynamics in order to develop ways to influence the aging process, and as a result, restrict cancer cell growth.

In addition to exploring the involvement of telomeres in premature aging diseases and interactions between the DNA damage machinery and telomeres, Karlseder studies the role of telomeres during the cell cycle. Previous studies on human cells have shown that telomeres change positions during cell division, suggesting they might also play a role in organizing DNA in the nucleus. But these studies provided only isolated snapshots of telomeres at various stages of the cell cycle.

In their new study, the Salk researchers used advanced time-lapse live-cell confocal microscopy to track telomere movement in real time throughout the cell cycle. They followed the telomeres for 20 hours in living cells by labeling them with molecules that glowed under the microscope. They also recorded the movement of chromatin, a combination of DNA and proteins that forms chromosomes.

The scientists found that the telomeres moved to the outer periphery of the nuclear envelope of each daughter cell nucleus as they assemble after mitosis, the stage of cell division during which the cell's DNA is duplicated to provide each daughter cell with its own copy. By exploring the underlying molecular pathways, the researchers determined that interactions between two proteins, RAP1 and Sun1, seem to tether the telomeres to the nuclear envelope. Sun1 alone was also capable of attracting the telomeres to the nuclear envelope, suggesting the protein is essential for the process and that other elements might be able to replace RAP1 during tethering.

"The tethering of telomeres to the nuclear envelope may serve as an anchor point to reorganize chromatin after each cell division, so that our DNA is correctly situated for gene expression," Karlseder says. "This tethering could also play a role in the maintenance of telomeres, thereby influencing aging, cancer development and other disorders associated with DNA damage. We plan to explore these possibilities in future experiments."


'/>"/>
Contact: Andy Hoang
ahoang@salk.edu
619-861-5811
Salk Institute
Source:Eurekalert  

Related biology news :

1. From Mediterranean coasts to Tatra Mountains and beyond: Plant chromosome number variation
2. Extra chromosome 21 removed from Down syndrome cell line
3. Western aspen trees commonly carry extra set of chromosomes
4. Study of fruit fly chromosomes improves understanding of evolution and fertility
5. Men can rest easy - sex chromosomes are here to stay
6. Discovery reveals chromosomes organize into yarns
7. Music with dinner: Whales sing during foraging season, not just while breeding
8. Abuse during childhood linked to adult-onset asthma in African-American women
9. Insight into DNA reprogramming during egg and sperm cell development
10. OHSU study shows that a molecule critical to nerve cells increases drammatically during hypertension
11. New risk factor identified for high blood pressure during pregnancy
Post Your Comments:
*Name:
*Comment:
*Email:
Related Image:
Chromosome 'anchors' organize DNA during cell division
(Date:4/28/2016)... Sweden , April 28, 2016 First ... M (139.9), up 966% compared with the first quarter of 2015 ... profit totaled SEK 589.1 M (loss: 18.8) and the operating margin ... 7.12 (loss: 0.32) Cash flow from operations was SEK ... The 2016 revenue guidance is unchanged, SEK 7,000-8,500 M. ...
(Date:4/15/2016)... CHICAGO , April 15, 2016  A ... companies make more accurate underwriting decisions in a ... offering timely, competitively priced and high-value life insurance ... health screenings. With Force Diagnostics, rapid ... and lifestyle data readings (blood pressure, weight, pulse, ...
(Date:3/31/2016)... 2016   LegacyXChange, ... "Company") LegacyXChange is excited to release its ... to be launched online site for trading 100% guaranteed ... will also provide potential shareholders a sense of the ... an industry that is notorious for fraud. The video ...
Breaking Biology News(10 mins):
(Date:4/28/2016)... NY (PRWEB) , ... April 28, 2016 , ... ... has made significant investments in recruiting top industry experts, and expanding its LATAM ... which provides industry-leading tools for clients to manage their clinical trial projects. , ...
(Date:4/27/2016)... ... ... Pittcon Organizing Committee is pleased to announce that Charles “Chuck” Gardner was named president ... Since then, he has served in a number of key leadership positions including secretary ... and exposition committees. In his professional career, Dr. Gardner is the director of product ...
(Date:4/27/2016)... British Virgin Islands (PRWEB) , ... April 27, ... ... Holding Company Ltd. (d/b/a Biohaven) is pleased to announce the appointment of John Tilton ... he was an Executive Director and one of the founding commercial leaders responsible ...
(Date:4/27/2016)... ... 27, 2016 , ... Global Stem Cells Group CEO Benito Novas ... founder of GSCG affiliate Kimera Labs in Miami. , In 2004, Ross received his ... transplantation for hematologic disorders and the suppression of graft vs. host disease (GVHD) under ...
Breaking Biology Technology: