Study of microRNA helps NIH scientists unlock secrets of immune cells

June 04, 2010

With the rapid and continuous advances in biotechnology, scientists are better able to see inside the nucleus of a cell to unlock the secrets of its genetic material. However, what happens outside of the nucleus has, in many ways, remained a mystery. Now, researchers with the National Institutes of Health are closer to understanding how activity outside of the nucleus determines a cell's behavior. They looked at mouse immune cells and examined the types, amount, and activity of microRNAs, genetic components that help regulate the production of proteins. Their study provides a map to the variety of microRNAs contained within mouse immune cells and reveals the complexity of cellular protein regulation. The study appears online in the journal Immunity.

An organism is made up of cells containing genetic material in the form of deoxyribonucleic acid (DNA) residing within the nucleus. An organism's entire collection of DNA is called its genome and consists of genes, short segments of DNA that code for proteins, and many long segments of DNA that do not contain genes. While each cell contains the entire genome, not all of a cell's genes are making proteins all of the time. Which genes are turned on and which are turned off, and when, determine the behavior of a cell, such as the type of cell it becomes, where it goes, and what it does.

"A plethora of cellular functions, ranging from development, differentiation, metabolism, and host defense, are impacted by protein levels," said Rafael Casellas, Ph.D., the study's principal investigator from the Genomics and Immunity Group of the NIH's National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS). " We were interested in discovering how microRNAs contribute to the regulation of these functions."

A cell makes proteins through a process called transcription, in which genes are copied from DNA into messenger ribonucleic acid (RNA), which travels from the nucleus into the body of the cell. Not all RNA transcribed from DNA are messenger RNA, however. There are many other forms of RNA that do not code for proteins. MicroRNAs (miRNAs), for example, are small strands of RNA that modulate the production of proteins from messenger RNA, thereby helping to regulate protein levels in the cell. Previous studies have shown that cells are very sensitive to fluctuations in miRNA levels, which require tight control in order to regulate protein activity effectively.

In the current study, the NIH scientists used a new microsequencing technology to comprehensively identify all of the different miRNAs existing in mouse immune cells. In addition to increasing the number of known miRNAs, the scientists also discovered several cellular mechanisms that regulate miRNA abundance. The study found that some miRNA constructs exist in a dormant state within the nucleus until they receive signals from the epigenome to become active. The epigenome regulates transcription and comprises all of the non-genetic material in the nucleus. Other miRNAs, the researchers determined, are not hampered by these epigenetic mechanisms and are controlled simply through transcription. However, for some of these miRNAs, abundance depends upon the amount of target messenger RNA available in the cell.

According to NIAMS Director Stephen I. Katz, M.D., Ph.D., "The data generated from this study represent a useful tool for immunologists and cell biologists to use for future studies on functional aspects of the immune system and basic miRNA biology."
-end-
More information about the NIAMS Genomics and Immunity section can be found at http://www.niams.nih.gov/Research/Ongoing_Research/Branch_Lab/Laboratory_Molecular_Immunogenetics/gis.asp.

The mission of the National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS), a part of the U.S. Department of Health and Human Services' National Institutes of Health, is to support research into the causes, treatment, and prevention of arthritis and musculoskeletal and skin diseases; the training of basic and clinical scientists to carry out this research; and the dissemination of information on research progress in these diseases. For more information about NIAMS, call the information clearinghouse at (301) 495-4484 or (877) 22-NIAMS (free call) or visit the NIAMS Web site at http://www.niams.nih.gov.

The National Institutes of Health (NIH) -- The Nation's Medical Research Agency -- includes 27 Institutes and Centers and is a component of the U.S. Department of Health and Human Services. It is the primary federal agency for conducting and supporting basic, clinical and translational medical research, and it investigates the causes, treatments, and cures for both common and rare diseases. For more information about NIH and its programs, visit www.nih.gov.

NIH/National Institute of Arthritis and Musculoskeletal and Skin Diseases

Related DNA Articles from Brightsurf:

A new twist on DNA origami
A team* of scientists from ASU and Shanghai Jiao Tong University (SJTU) led by Hao Yan, ASU's Milton Glick Professor in the School of Molecular Sciences, and director of the ASU Biodesign Institute's Center for Molecular Design and Biomimetics, has just announced the creation of a new type of meta-DNA structures that will open up the fields of optoelectronics (including information storage and encryption) as well as synthetic biology.

Solving a DNA mystery
''A watched pot never boils,'' as the saying goes, but that was not the case for UC Santa Barbara researchers watching a ''pot'' of liquids formed from DNA.

Junk DNA might be really, really useful for biocomputing
When you don't understand how things work, it's not unusual to think of them as just plain old junk.

Designing DNA from scratch: Engineering the functions of micrometer-sized DNA droplets
Scientists at Tokyo Institute of Technology (Tokyo Tech) have constructed ''DNA droplets'' comprising designed DNA nanostructures.

Does DNA in the water tell us how many fish are there?
Researchers have developed a new non-invasive method to count individual fish by measuring the concentration of environmental DNA in the water, which could be applied for quantitative monitoring of aquatic ecosystems.

Zigzag DNA
How the cell organizes DNA into tightly packed chromosomes. Nature publication by Delft University of Technology and EMBL Heidelberg.

Scientists now know what DNA's chaperone looks like
Researchers have discovered the structure of the FACT protein -- a mysterious protein central to the functioning of DNA.

DNA is like everything else: it's not what you have, but how you use it
A new paradigm for reading out genetic information in DNA is described by Dr.

A new spin on DNA
For decades, researchers have chased ways to study biological machines.

From face to DNA: New method aims to improve match between DNA sample and face database
Predicting what someone's face looks like based on a DNA sample remains a hard nut to crack for science.

Read More: DNA News and DNA Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.