RNA molecules are used by cells to make proteins. They are generally thought to be "silent" when stowed in cytoplasmic granules. But a protein mutated in some ALS patients forms granules that permit translation of stored RNAs, according to a study in The Journal of Cell Biology. The finding identifies a new mechanism that could contribute to the pathology of the disease.
ALS, often referred to as "Lou Gehrig's Disease," is a progressive neurodegenerative disease that affects nerve cells in the brain and the spinal cord. Although the cause of ALS is not completely understood, researchers have been increasingly focused on RNA processing as an important cause of disease symptoms.
RNAs are gregarious, clustering with other RNA molecules and proteins to form RNP (ribonucleoprotein) complexes. RNPs then can gather into larger, more complex structures within the cell called granules. There are several kinds of granules, some that are always present and others that appear under stress, and researchers have generally thought that RNAs in granules are not translated into proteins.
The results suggest a new mechanism that could potentially drive ALS, in which misdirection of RNA translation, rather than RNA silencing, might contribute to disease.