Laser microscopy reveals gene splicing

Compiled by BioPhotonics staff

A new laser-based microscopy method allows scientists to decipher basic biology and understand how diseases related to cellular micromachines occur.

The microscope, developed at Brandeis University, uses lasers to study the splicing of pre-messenger RNA molecules, an essential process in creating proteins to sustain advanced organisms such as humans. The splicing process is carried out by cellular micromachines called spliceosomes. By understanding how the process works, the researchers hope to find therapies that fix the splicing process in cases where it does not work properly. Their work appears in the March 11, 2011, issue of Science (doi: 10.1126/science.1198830).

A custom microscope developed at Brandeis University uses lasers emitting various wavelengths to illuminate biomolecules and study the assembly of spliceosomes. Each fluorescent biomolecule is “turned on” by a different laser, allowing different molecules to be identified and studied simultaneously. Courtesy of Diana Katherine Hunt.

Because genomic DNA resembles a zip file, which carries a large amount of information in a small amount of space, splicing a gene allows scientists to decompress the information so the cell can read it before a particular protein is made. Scientists have found that the regions of a gene that do not code for proteins, called introns, often interrupt the regions that do, called exons. They had to remove the introns so the remaining pieces could be spliced together to form appropriate proteins.

To make this happen, a collaboration of scientists from Brandeis, the University of Massachusetts Medical School and Columbia University spent more than five years creating a specialized light microscope to watch single protein molecules and to develop a methodology for studying the proteins in their complex environment.

To view the spliceosome in the act of splicing, the scientists tagged single yeast components with fluorescent dyes and placed the sample in the microscope. A laser was used to light up the individual tagged molecules, making it possible to watch the various stages of the splicing process.

The researchers are also studying the process by which an RNA copy is made, known as transcription, and processes by which cells change their shape and move. Their findings can be generally applied to a range of biological problems that previously were difficult to study.