Featured Research

from universities, journals, and other organizations

Newly Identified Role For 'Power Plants' In Human Cells Could Lead To Targeted Therapies

Date:
June 25, 2008
Source:
Ohio State University
Summary:
Scientists have determined that human cells are able to shift important gene products into their own mitochondria, considered the power plants of cells. The finding could eventually lead to therapies for dozens of diseases. The gene products, known as tRNAs, assemble amino acids for the production of proteins within mitochondria. If the mitochondrial tRNA genes are defective or missing, and proteins are not manufactured, the mitochondria are unable to generate adequate energy.

Electron micrograph of a single mitochondrion showing the organized arrangement of the protein matrix and the inner mitochondrial membranes.
Credit: U.S. Dept. of Health and Human Services/National Institutes of Health

Scientists have determined that human cells are able to shift important gene products into their own mitochondria, considered the power plants of cells. The finding could eventually lead to therapies for dozens of diseases.

Related Articles


The gene products, known as tRNAs, assemble amino acids for the production of proteins within mitochondria. If the mitochondrial tRNA genes are defective or missing, and proteins are not manufactured, the mitochondria are unable to generate adequate energy.

Defective tRNAs are believed to be the cause of about 60 percent of conditions traced to malfunctions in the mitochondria. The range of related conditions includes diabetes, hearing loss and a number of neurological disorders, depending on which kinds of cells are affected.

Mitochondria are encased in their own membrane, making them a structure that is complicated to study. Previous research has suggested that only in lower organisms, such as protozoans, yeast and plants, can tRNAs be imported to the mitochondria from the cell cytoplasm, the fluid-based area that contains most components of a cell.

But in this new research, scientists determined that tRNAs can be imported from cytoplasm to mitochondria in rat liver cells and human cells as well.

“This was totally unexpected, to find an innate, built-in mechanism that we humans have,” said Juan Alfonzo, senior author of the study and an assistant professor of microbiology at Ohio State University.

The finding broadens the study of therapeutic options involving attempts to introduce healthy tRNAs to the defective mitochondria of ill patients, Alfonzo said.

“If you have a mutation in a tRNA that you suspect is involved in disease, you theoretically should be able to bring a healthy tRNA from the cytoplasm into the mitochondria and correct the malfunction,” he said.

The research appears online this week in the Proceedings of the National Academy of Sciences.

Alfonzo noted that the current study was able to determine that the import of tRNAs occurs, but it leaves open the question of how it happens.

He and colleagues conducted experiments first in rat liver cells to test whether tRNA import occurs in mammals at all. When the import was observed in rat mitochondria, they extended the study to human cells.

The finding that tRNA import occurs in humans can set in motion an entirely new line of research into therapeutic options for patients with diseases caused by mitochondrial defects. There appears to be no way to introduce healthy tRNAs directly into mitochondria because their membranes have proven impenetrable to such outside interference, Alfonzo explained.

So scientists know they would have to rely on the import process that starts in the cytoplasm to transfer healthy tRNAs to damaged mitochondria and improve energy production.

Until now, researchers didn’t know the human mitochondria had that import ability, so scientists were going to try using protozoan or yeast cells to manipulate the import process in human cells.

“What we are saying is you don’t need to bring up new machinery from a different organism because human cells already come equipped with their own way to import tRNAs. There is no need to cross species,” Alfonzo said. “What we need to know now is what proteins are involved in the import mechanism so we can exploit the process for therapy.”

One compound already identified as essential for the process is Adenosine-5-triphosphate, or ATP, a compound associated with energy transport in cells. Alfonzo and colleagues demonstrated ATP’s role in the process using cells from a patient with a specific type of epilepsy called MERRF. This disease is characterized by a mitochondrial tRNA mutation leading to a drastic reduction in the mitochondria’s ability to generate ATP, which in turn hinders the import of tRNAs into the mitochondria of people with this disease.

When ATP was introduced to the mitochondria of these diseased cells, the import process of tRNAs from the cytoplasm to the mitochondria was restored.

“These were cells from an actual patient, so this also makes the argument that we don’t need a surrogate system from other organisms to set the import process in motion,” Alfonzo said.

Alfonzo conducted this work with Mary Anne Rubio of Ohio State’s Department of Microbiology; Jesse Rinehart, Bethany Krett and Dieter Sφll of Yale University’s departments of molecular biophysics and biochemistry and chemistry; and Stιphane Duvezin-Caubet and Andreas Reichert of the Institute for Physiological Chemistry at Ludwig-Maximilians-University in Munich.

This research was supported by grants from the Deutsche Forschungsgemeinschaft (German Research Foundation), the National Institute of General Medical Sciences and the National Science Foundation.


Story Source:

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


Cite This Page:

Ohio State University. "Newly Identified Role For 'Power Plants' In Human Cells Could Lead To Targeted Therapies." ScienceDaily. ScienceDaily, 25 June 2008. <www.sciencedaily.com/releases/2008/06/080624110949.htm>.
Ohio State University. (2008, June 25). Newly Identified Role For 'Power Plants' In Human Cells Could Lead To Targeted Therapies. ScienceDaily. Retrieved December 27, 2014 from www.sciencedaily.com/releases/2008/06/080624110949.htm
Ohio State University. "Newly Identified Role For 'Power Plants' In Human Cells Could Lead To Targeted Therapies." ScienceDaily. www.sciencedaily.com/releases/2008/06/080624110949.htm (accessed December 27, 2014).

Share This


More From ScienceDaily



More Plants & Animals News

Saturday, December 27, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Breeding Christmas Trees Without Needle Mess

Breeding Christmas Trees Without Needle Mess

AP (Dec. 26, 2014) — The presents are unwrapped. Now it's time for another Yuletide tradition: cleaning up the needles that are falling off your Christmas tree. Scientist hope to make that process a ghost of Christmas past. (Dec. 26) Video provided by AP
Powered by NewsLook.com
Venemous White Cobra Gets New Home

Venemous White Cobra Gets New Home

Reuters - Light News Video Online (Dec. 24, 2014) — A venemous white cobra gets a new home at the San Diego Zoo, following a dramatic capture and months of quarantine. Sharon Reich reports Video provided by Reuters
Powered by NewsLook.com
Christmas Trees And Bugs Are Seemingly Symbiotic

Christmas Trees And Bugs Are Seemingly Symbiotic

Newsy (Dec. 24, 2014) — The National Christmas Tree Association says bugs in trees are a relatively small problem, but recommends giving your tree a good shake anyway. Video provided by Newsy
Powered by NewsLook.com
Uruguay Chooses 'smart' Farming Methods for Ambitious Goals

Uruguay Chooses 'smart' Farming Methods for Ambitious Goals

AFP (Dec. 24, 2014) — Using GM crops, genetically chosen cows, and technology like satellites and drones, Uruguay - with a population of just 3 million people - is aiming to produce enough food to feed 50 million. Duration: 03:10 Video provided by AFP
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:

Strange & Offbeat Stories

 

Plants & Animals

Earth & Climate

Fossils & Ruins

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