RNA: More Than Just a Genetic Messenger

In the future, the diagnosis and treatment of genetically-related diseases will be made easier by the work of bioscientists studying cell genetics today. Their current struggle is the development of a genetic dictionary that defines the function of individual genes. Deciphering individual gene function is a matter of deduction: researchers turn off a gene's expression and then study the effect of the absence of the gene on the cell. Until recently, that research has hinged on slow, laborious techniques that knock out one target gene at a time. Even when these so-called knockout strategies are successful, the resulting embryos may not be viable for study.

Fortunately, new discoveries about what ribonucleic acid (RNA) does in a cell, and what it can be made to do, are accelerating the pace of gene function research. For example, an exciting alternative to knockout strategies called RNA interference (RNAi) provides a more efficient way to switch off the expression of targeted genes, allowing more experimentation to be performed in less time. RNAi works by silencing genes whose genetic sequence corresponds to a specific piece of RNA. Until recently this method worked for plants and lower-order animals. However, when it came to mammals, RNAi sometimes resulted in the complete failure of protein production.

Scientists at the Max Planck Institute in Germany now report that they have successfully shut off genes in mammalian cell lines, including the human. They did it by using specially-made, double-stranded RNA molecules that are shorter than the RNA used in previous attempts. Scientists still aren't completely sure why the shorter, double-stranded RNA works, but they believe the RNA molecules degrade messenger RNA and prevent protein synthesis.

Cut and paste with RNA

It appears that RNA is a much more capable molecule than previously thought. Not only do some varieties of RNA escort amino acids and instructions about protein production to the waiting ribosome, other RNAs in the cell nucleus have a role in constructing an important type of RNA known as messenger RNA (mRNA).

The genesis of mRNA, in a process called transcription, is still being studied. Scientists know that important coding regions of genetic information transcribed from DNA are mysteriously spliced together to create mRNA. Non-coding regions of DNA that do not carry essential genetic sequences are left out. It has become clear that small RNAs in the nucleus work with proteins to create the spliceosome, which acts to remove non-coding genetic sequences from mRNA. Researchers now believe that it is the RNA portion of the spliceosome, not the protein, that takes the lead in stripping away the non-coding sequences. This instance of RNA behaving as a catalyst has sparked interest in developing and exploiting RNA's other possible uses. In fact, a new field of study, "ribozymology," has arisen to explore ways to use RNA as an enzyme.

Tools for discovery

As interest in RNA has risen among basic and applied scientists, the value of precision measurement tools for RNA quantitation and characterization has also increased. Applications ranging from gene expression analysis to Northern blotting to construction of cDNA libraries rely on accurate RNA measurements.

Extraction of RNA is a difficult process. Unwanted contaminants and ribonucleases conspire to thwart exact measurements by degrading samples. Low extraction yields from small amounts of tissue make effective use of small samples even more crucial. Formerly acceptable methods of RNA characterization such as agarose gel electrophoresis are no longer adequate for many of today's demanding applications. Gene expression experiments, for example, require information about sample constituents, possible contaminants, and degree of degradation that are not available with traditional electrophoresis.

The right tools for the job

As a leading manufacturer of accurate, highly sensitive solutions for life scientists, Agilent answers the researchers' ever-increasing need for better results in less time. Two recent improvements are helping advance the cause of RNA research:

• Agilent RNA 6000 Nano LabChip kit:
  Taking a step beyond the RNA 6000 LabChip kit for the Agilent 2100 bioanalyzer, this kit provides enhanced quantitation and comparison of samples. It performs automated quality control of total and messenger RNA. A single analysis can provide quality control and concentration measurements, usually without additional UV or ribogreen measurements. What's more, sample consumption is low, preserving precious sample for further analysis.
   
• Agilent DNA microarray scanner:
  This automated, 48-slide, walkaway scanner incorporates a capability called dynamic autofocus. Continual focus adjustments reduce the impact of measurement noise and permit images with very high sensitivity and 5-micron resolution. Efficient comparison of results in one microarray experiment is possible through two-color simultaneous scanning. In addition, the DNA microarray scanner can read microarrays from Agilent and many other manufacturers as well as in-house spotted microarrays.

Through innovations such as these, Agilent is working to assist the researchers who study RNA and mRNA. Improved research tools will help bioscientists add new knowledge and deeper understanding at a faster rate, bringing the world closer to a future in which the diagnosis and treatment of genetically-related diseases is faster and easier.

For more information

To learn more about Agilent's solutions for RNA analysis, please visit the Gene Expression section of our Web site. For more information about other Agilent chemical analysis products and resources, please return to the Life Sciences/Chemical Analysis main page.