CLIP Identifies Nova-Regulated RNA Networks in the Brain

Nova proteins are neuron-specific antigens targeted in paraneoplastic opsoclonus myoclonus ataxia (POMA), an autoimmune neurologic disease characterized by abnormal motor inhibition. Nova proteins regulate neuronal pre-messenger RNA splicing by directly binding to RNA. To identify Nova RNA targets, we developed a method to purify protein-RNA complexes from mouse brain with the use of ultraviolet cross-linking and immunoprecipitation (CLIP). Thirty-four transcripts were identified multiple times by Nova CLIP. Three-quarters of these encode proteins that function at the neuronal synapse, and one-third are involved in neuronal inhibition. Splicing targets confirmed in$Nova^{-/-}$mice include c-Jun N-terminal kinase 2, neogenin, and gephyrin; the latter encodes a protein that clusters inhibitory$\gamma-aminobutyric$acid and glycine receptors, two previously identified Nova splicing targets. Thus, CLIP reveals that Nova coordinately regulates a biologically coherent set of RNAs encoding multiple components of the inhibitory synapse, an observation that may relate to the cause of abnormal motor inhibition in POMA.