Scientists have now developed an easier way to track and image messenger RNA molecules. Researchers from the Massachusetts Institute of Technology refined a recently discovered technique to make it easier and less expensive. A paper just published in Nature Biotechnology details their new method and how it can be used to study gene expression.
Messenger RNA molecules, or mRNA, carry copies of the DNA code to ribosomes. From there, the ribosomes can build the proper proteins. These tiny molecules have been difficult to study in the past but are critical for understanding how gene expression works. Last year, researchers reported a technique for tagging and magnifying these molecules. They embedded brain tissue samples in a polymer, called polyacrylate, which would swell up after the addition of water. After labeling the target proteins with chemical dyes, the proteins holding the tissue together would be broken down, allowing the tissue sample to swell along with the gel. This increased the overall size of the sample, making it easier to get high resolution images. The problem with this method was that it used expensive chemical reagents and complicated techniques that would be impractical for most laboratories.
To address these problems, the researchers relied on a different molecule for connecting the targets to the polymer gel. This new molecule, known as AcX, is less expensive and readily available. The researchers were able to use AcX and an updated technique to obtain high-quality images of tissue samples. They were able to achieve a resolution of about 70 nm, previously only achievable with specialized microscopes beyond the budget of the average laboratory. In the study, the researchers used this new form of expansion microscopy to image many types of samples, including brain and lung tissue.
The researchers believe that this method could be effectively used by laboratories to study mRNA and similar molecules. The authors note that expansion microscopy techniques can allow researchers to determine how cells control gene expression, important knowledge for developing treatments for genetic diseases.
Paul W Tillberg et al. Protein-retention expansion microscopy of cells and tissues labeled using standard fluorescent proteins and antibodies. Nature Biotechnology (2016).