RNA silencing is a mechanism for selectively turning genes off and on within a cell. Strands of RNA known as small interfering RNA (siRNA) can degrade the cell's own RNA when it is no longer needed and break it down for future use. The cell can also attack foreign and mutated RNA to prevent it from reproducing. This prevents the outbreak or continued spread of disease in the organism as a whole and is an important defense mechanism for everything from weeds to whales.
Within the cell, messenger RNA (mRNA) carries the instructions for strings of proteins a cell can use in various functions. A cell's content of mRNA at any given time can be variable depending on what kind of cell it is and its life cycle stage. One use for RNA silencing is in the destruction of mRNA that is no longer needed. Enzymes in the cell can pull apart the material and recycle the components for use in other projects. This allows cells to self regulate and control a number of different ongoing processes that help the cell function.
When foreign RNA enters a cell, RNA silencing can also occur. Enzymes in the cell know how to recognize double-stranded RNA and also know it does not belong, since the body only produces the single-stranded form. These enzymes can pull apart viral RNA with two strands so it cannot take a cell over and begin using it to produce more viruses. Cells can also recognize foreign or mutated RNA and use RNA silencing to prevent reproduction and remove it.
In addition to being important for regulation of cellular activities and defense against hostile organisms, RNA silencing also has scientific applications. Researchers can use this technique to deactivate genes. It can play a role in genetic engineering, where the goal is to tightly control expressed genetic traits in organisms like plants. Researchers can use RNA silencing to shape the development of an organism and make it more commercially useful.
Researchers study RNA silencing in labs all over the world. Their work includes monitoring the regulatory processes used by cells as well as developing techniques to interfere with cellular RNA for their projects. Scientists with an interest in this type of research typically have graduate degrees and may have completed postdoctoral work as part of their training. They can work for pharmaceutical companies, agriculture firms, nonprofits with an interest in health, and government agencies that study genetics.