In a study in the advance online edition of Nature Structural and Molecular Biology, researchers from Albert Einstein College of Medicine describe a technique for looking more precisely at a fundamental step of a cell's life - a gene, DNA, being read into a message, mRNA.
The technique could provide a window into the process by which genes are switched on inappropriately, causing disease.
The new technique provides a detailed look into processes that until now were proven but never visualized. The more detailed view of DNA being made into RNA in a single cell will help answer questions about how much of a gene is made over time and how much that level varies from cell to cell. Insight into how genes work at a more precise level, ultimately advances understanding of disease mechanisms that trigger cancer, for example, which arise when genes no longer work at their correct capacity or time.
"The classic textbook cartoon illustration of a single strand of DNA with little mRNA pieces coming off it can now be shown with real photographs," explained Daniel Zenklusen, Ph.D., an Einstein post-doctoral fellow and first author of the study. The technique was developed in the laboratory of Robert Singer, Ph.D., co-chair and professor of anatomy and structural biology at Einstein.
The new technology is a powerful refinement of fluorescent in-situ hybridization (FISH), developed in Dr. Singer's laboratory more than 26 years ago. FISH is now a widely used research tool to study gene activation; that is how much a gene has been "turned on" in groups of cells. FISH is also used in genetic counseling to detect the presence of gene features that diagnose conditions including Down's syndrome or Prader-Willi syndrome.
Advances in fluorescence, microscopy and data analysis enabled the more powerful FISH application described in the paper. Until this work, FISH could only be used to look at genes or their messages that are present at very high levels and only in tissues, not at the smaller level of the cell. However, this it the first time that all the individual mRNA molecules within single cells can be counted.
Dr. Singer's "single RNA counting" technique has the potential to change some fundamental theories about how genes are regulated. As Dr. Singer explained, "our study using this new technique has already generated enough new ideas to keep students busy for the next 10 years."