Featured Research

from universities, journals, and other organizations

Scientists sever molecular signals that prolific parasite uses to puppeteer cells

Date:
April 24, 2010
Source:
American Society for Biochemistry and Molecular Biology
Summary:
Scientists studying a cunning parasite that has commandeered the cells of almost half the world's human population have begun to zero in on the molecular signals that must be severed to free the organism's cellular hostages.

Scientists studying a cunning parasite that has commandeered the cells of almost half the world's human population have begun to zero in on the molecular signals that must be severed to free the organism's cellular hostages.

While Toxoplasma gondii is not as widely known by the public as some of its more notorious parasitic brethren, it has been hijacking the cells of human and animal hosts for eons and is particularly dangerous to those with compromised and/or underdeveloped immune systems.

"We have understood for some time now that Toxoplasma can co-opt the biological processes of its host cell, but there's still a lot we don't know about how this happens and what benefit the parasite derives," said Dr. Amos Orlofsky at Albert Einstein College of Medicine of Yeshiva University, one of the co-authors of a new paper in the Journal of Biological Chemistry that reveals how blocking certain signals within a cell can liberate it from its captor.

Toxoplasma is a crafty single-celled organism that typically begins its life cycle in the warm body of a small mammal, such as a rat. While there, it reprograms the rat's gut instinct to avoid cats and, thus, makes the rat far more likely to get gobbled up. Toxoplasma's ultimate goal is, in fact, to get eaten by a cat, because, once it settles into the feline's gastrointestinal tract, it begins the second stage of its life cycle: laying the next generation of eggs that will be shed in feces and acquired by the next rat.

Seeing as how humans usually aren't eaten by cats, Toxoplasma doesn't seek them out as hosts. But, humans are exposed to the parasite at a fairly high rate, usually while changing cat litter or eating unwashed vegetables or undercooked meat.

"Toxoplasma is a major cause of mortality in AIDS patients worldwide, and it's also a serious problem for transplant recipients and for infants whose mothers became infected during pregnancy. There is also some reason to be concerned about possible neurologic effects in those who are infected but apparently healthy," Orlofsky explained. "Current medications are limited by side effects, and new approaches to dealing with this highly sophisticated and successful microbe are urgently needed."

In collaboration with colleague Louis M. Weiss and then-graduate-student Yubao Wang, who is now a postdoctoral fellow at Harvard University, Orlofsky set out to identify which cellular signals are used by Toxoplasma to capture and rearrange key structures in the host cell. He described those cellular signals as, essentially, the strings used by the parasite-puppeteer to manipulate the behavior of the cell.

They focused on one particular cellular structure known as the centrosome, which serves as the networking hub for fibers that direct traffic within the cell. The centrosome also controls the direction in which the cell moves within the body, but, when infected with Toxoplasma, it doesn't take its normal routes.

Orlofsky said this suggests that Toxoplasma disables the steering of the host cell by taking hold of the cell's "rudder."

"We infected cells in a Petri dish with Toxoplasma and then scratched the dish to create a 'wound.' Normally, cells next to the wound sense the new emptiness next to them and respond by trying to fill the wound, and the cell then starts moving in that direction," Orlofsky said. "We discovered that Toxoplasma-infected cells don't do this: Their captured centrosomes fail to move toward the wound, and the entire cell fails to move as well."

When the team "liberated" the centrosome of the infected cell, by inhibiting certain signals, it re-oriented itself toward the wound and was able to move in the proper direction.

"These results give us some insight into what the parasite may be trying to accomplish. That is, it seems to be crippling the ability of host cells to respond to signals that say 'move over here'. That could make all the difference for the body's ability to make a quick immune response, which may depend on infected cells and immune-response cells moving toward each other and interacting."

Orlofsky's team hopes learning more about these signals and how to manipulate them may yield tools for protecting multiple host-cell functions from total parasite takeover. These tools could lead to improved treatments or preventive measures.

"If our speculation is correct about the effects of the parasite on the immune response, then one could envisage a live vaccine based on disabled Toxoplasma that, among their other engineered defects, lack the ability to hold the cell's rudder and so elicit a stronger immune response," Orlofsky said.

The team's research was carried out at the departments of medicine and pathology at Albert Einstein College of Medicine and was funded by the National Institutes of Health. The resulting paper was published on the Journal of Biological Chemistry's Web site March 17 and will appear in a forthcoming print issue.


Story Source:

The above story is based on materials provided by American Society for Biochemistry and Molecular Biology. Note: Materials may be edited for content and length.


Journal Reference:

  1. Y. Wang, L. M. Weiss, A. Orlofsky. Coordinate control of host centrosome position, organelle distribution and migratory response by Toxoplasma gondii via host mTORC2. Journal of Biological Chemistry, 2010; DOI: 10.1074/jbc.M109.095778

Cite This Page:

American Society for Biochemistry and Molecular Biology. "Scientists sever molecular signals that prolific parasite uses to puppeteer cells." ScienceDaily. ScienceDaily, 24 April 2010. <www.sciencedaily.com/releases/2010/04/100420132837.htm>.
American Society for Biochemistry and Molecular Biology. (2010, April 24). Scientists sever molecular signals that prolific parasite uses to puppeteer cells. ScienceDaily. Retrieved April 21, 2014 from www.sciencedaily.com/releases/2010/04/100420132837.htm
American Society for Biochemistry and Molecular Biology. "Scientists sever molecular signals that prolific parasite uses to puppeteer cells." ScienceDaily. www.sciencedaily.com/releases/2010/04/100420132837.htm (accessed April 21, 2014).

Share This



More Health & Medicine News

Monday, April 21, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Breakfast Foods Are Getting Pricier

Breakfast Foods Are Getting Pricier

AP (Apr. 21, 2014) Breakfast is now being served with a side of sticker shock. The cost of morning staples like bacon, coffee and orange juice is on the rise because of global supply problems. (April 21) Video provided by AP
Powered by NewsLook.com
Nine-Month-Old Baby Can't Open His Mouth

Nine-Month-Old Baby Can't Open His Mouth

Newsy (Apr. 19, 2014) Nine-month-old Wyatt Scott was born with a rare disorder called congenital trismus, which prevents him from opening his mouth. Video provided by Newsy
Powered by NewsLook.com
'Holy Grail' Of Weight Loss? New Find Could Be It

'Holy Grail' Of Weight Loss? New Find Could Be It

Newsy (Apr. 18, 2014) In a potential breakthrough for future obesity treatments, scientists have used MRI scans to pinpoint brown fat in a living adult for the first time. Video provided by Newsy
Powered by NewsLook.com
Little Progress Made In Fighting Food Poisoning, CDC Says

Little Progress Made In Fighting Food Poisoning, CDC Says

Newsy (Apr. 18, 2014) A new report shows rates of two foodborne infections increased in the U.S. in recent years, while salmonella actually dropped 9 percent. 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