Science Today

Researchers pinpoint a small RNA that spurs cells to manufacture a particular splice variant of a key neuronal protein, potentially promoting Alzheimer's disease (AD) or other types of neurodegeneration. The study appears in the May 30 issue of The Journal of Cell Biology. Like a movie with an alternate ending, a protein can come in more than one version. Although scientists have identified numerous proteins and RNAs that influence alternative splicing, they haven't deciphered how cells fine-tune the process to produce specific protein versions. Four years ago, researchers identified a set of 30 small, noncoding RNAs that they suspected help regulate gene expression. Researchers show that the small RNA 38A spurs cells to manufacture Var IV, a splice variant of a key neuronal protein, and potentially promote Alzheimer's disease. In this image, Var IV (green) is prevalent in cells that make extra 38A (left) but rare in control cells (right). (Credit: Massone, S., et al. 201...

A detailed comparison of DNA and RNA in human cells has uncovered a surprising number of cases where the corresponding sequences are not, as has long been assumed, identical. The RNA-DNA differences generate proteins that do not precisely match the genes that encode them. The finding, published May 19, 2011, in Science Express, suggests that unknown cellular processes are acting on RNA to generate a sequence that is not an exact replica of the DNA from which it is copied. Vivian Cheung, the Howard Hughes Medical Institute investigator who led the study, says the RNA-DNA differences, which were found in the 27 individuals whose genetic sequences were analyzed, are a previously unrecognized source of genetic diversity that should be taken into account in future studies. Genes have long been considered the genetic blueprints for all of the proteins in a cell. To produce a protein, a gene's DNA sequence is copied, or transcribed, into RNA. That RNA copy specifies which amino acids wi...