Alternative splicing: decoding an expansive regulatory layer.

Alternative splicing (AS) is the process by which splice sites in precursor (pre)-mRNA are differentially selected to produce multiple mRNA and protein isoforms. During the past few years the application of genome-wide profiling technologies coupled with bioinformatic approaches has transformed our understanding of AS complexity and regulation. These studies are further driving research directed at elucidating the functions of networks of regulated AS events in the context of normal physiology and disease. Major strides have also been made in understanding how AS is functionally integrated with- and coupled to- gene regulation at the level of chromatin and transcription. Particularly intriguing is the discovery of new AS 'switches' that control transcriptional networks required for animal development and behavior.