GENETIC DEPLETION REVEALS AN ESSENTIAL ROLE FOR AN SR PROTEIN SPLICING FACTOR IN VERTEBRATE CELLS

SR proteins are essential for the splicing of messenger RNA precursors in vitro, where they also alter splice site selection in a concentrat ion-dependent manner. Although experiments involving overexpression or dominant mutations have confirmed that these proteins can influence R NA processing decisions in vivo, similar results with loss-of-function mutations have been lacking. Now, a system for genetic depletion of t he chicken B cell line DT40 has revealed that the SR protein ASF/SF2 ( alternative splicing factor/splicing factor 2) is essential for viabil ity in these cells((1)). This study opens the way for a complete funct ional dissection of this protein, and other SR proteins, in vivo.