About My Health Careers Internship MedBlogs Contact us
Medindia LOGIN REGISTER
Advertisement

Researchers Find New Mechanism Behind Neurodegeneration in Mice

by Bidita Debnath on July 28, 2014 at 11:24 PM
Font : A-A+

 Researchers Find New Mechanism Behind Neurodegeneration in Mice

A research team have pinpointed a surprising mechanism behind neurodegeneration in mice, one that involves a defect in a key component of the cellular machinery that makes proteins, known as transfer RNA or tRNA.

The research team was led by Jackson Laboratory Professor and Howard Hughes Investigator Susan Ackerman, Ph.D. The researchers report in the journal Science that a mutation in a gene that produces tRNAs operating only in the central nervous system results in a "stalling" or pausing of the protein production process in the neuronal ribosomes. When another protein the researchers identified, GTPBP2, is also missing, neurodegeneration results.

Advertisement

"Our study demonstrates that individual tRNA genes can be tissue-specifically expressed in vertebrates," Ackerman says, "and mutations in such genes may cause disease or modify other phenotypes. This is a new area to look for disease mechanisms."

Neurodegeneration—the process through which mature neurons decay and ultimately die—is poorly understood, yet it underlies major human diseases, such as Alzheimer's disease, Parkinson's disease, Huntington's disease and ALS (amyotrophic lateral sclerosis, also known as Lou Gehrig's disease).
Advertisement

While the causes of neurodegeneration are still coming to light, there is mounting evidence that neurons are exquisitely sensitive—much more so than other types of cells—to disruptions in how proteins are made and how they fold.

tRNAs are critical in translating the genetic code into proteins, the workhorses of the cell. tRNAs possess a characteristic cloverleaf shape with two distinct "business" ends—one that reads out the genetic code in three-letter increments (or triplets), and another that transports the protein building block specified by each triplet (known as an amino acid).

In higher organisms, tRNAs are strikingly diverse. For example, while there are 61 distinct triplets that are recognized by tRNAs in humans, the human genome contains roughly 500 tRNA genes. To date little is known about why they are so numerous, whether they carry out overlapping or redundant functions, or whether they possibly have roles beyond the making of proteins.

"Multiple genes encode almost all tRNA types," Ackerman says. "In fact, AGA codons are decoded by five tRNAs in mice. Until now, this apparent redundancy has caused us to completely overlook the disease-causing potential of mutations in tRNAs, as well as other repetitive genes."

Ackerman and her colleagues at The Jackson Laboratory in Bar Harbor, Maine, and Farmington, Conn., The Scripps Research Institute in LaJolla, Calif., and Kumamoto University in Japan pinpointed a mutation in the tRNA gene n-Tr20 as a genetic culprit behind the neurodegeneration observed in mice lacking GTPBP2.

Remarkably, the tRNA's activity is confined to the brain and other parts of the central nervous system, in both mice and humans. The tRNA encoded by n-Tr20 recognizes the triplet code, AGA (which specifies the amino acid arginine).

The n-Tr20 defect disrupts how proteins are made. Specifically, it causes the "factories" responsible for synthesizing proteins, called ribosomes, to stall when they encounter an AGA triplet.

Such stalling can be largely overcome, thanks to the work of a partner protein called GTPBP2. But when this partner is missing—as it is in the mutant mice that Ackerman and her colleagues studied—the stalling intensifies. This is thought to be a driving force behind the neurodegeneration seen in these mice.

Source: Eurekalert
Advertisement

Advertisement
News A-Z
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
News Category
What's New on Medindia
Health Benefits of Sea Buckthorn
Contraceptive Pills in Polycystic Ovary Syndrome (PCOS) Curtail Type 2 Diabetes Risk
Mushroom May Help Cut Down the Odds of Developing Depression
View all

Medindia Newsletters Subscribe to our Free Newsletters!
Terms & Conditions and Privacy Policy.


Recommended Reading
Researchers Study Bank Voles to Know About Prion Disease Transmission and Neurodegeneration
Previous research has shown that when cannibals ate brains of people who died from prion disease, .....
New Genetic Forms of Neurodegeneration Discovered
A doubling of the number of known cases of hereditary spastic paraplegia- a neurodegenerative ......
Defective Processes in Removing Cellular Waste Reason Behind Neurodegeneration in Gaucher Disease
A new study reveals that the neurodegeneration caused by Gaucher disease is due to defects in the .....
Gene Involved in Neurodegeneration Linked to the Circadian Clock
A gene involved in neurodegenerative disease plays an important role in the function of the ......

Disclaimer - All information and content on this site are for information and educational purposes only. The information should not be used for either diagnosis or treatment or both for any health related problem or disease. Always seek the advice of a qualified physician for medical diagnosis and treatment. Full Disclaimer

© All Rights Reserved 1997 - 2021

This site uses cookies to deliver our services. By using our site, you acknowledge that you have read and understand our Cookie Policy, Privacy Policy, and our Terms of Use