- M.D. Sury
- E. McShane
- L.R. Hernandez-Miranda
- C. Birchmeier
- M. Selbach
- Molecular & Cellular Proteomics
- Mol Cell Proteomics 14 (1): 50-65
The c-Jun N-terminal kinase (JNK) is an important mediator of physiological and pathophysiological processes in the central nervous system. Importantly, JNK is not only involved in neuronal cell death but also plays a significant role in neuronal differentiation and regeneration. For example, nerve growth factor (NGF) induces JNK-dependent neuronal differentiation in several model systems. The mechanism how JNK mediates neuronal differentiation is not well understood. Here, we employ a proteomic strategy to better characterize the function of JNK during neuronal differentiation. We use SILAC-based quantitative proteomics to identify proteins that interact with JNK in PC12 cells in an NGF-dependent manner. Intriguingly, we find that JNK interacts with neuronal transport granule proteins such as Sfpq and Nono upon NGF treatment. We validate the specificity of these interactions by showing that they are disrupted by a specific peptide inhibitor that blocks the interaction of JNK with its substrates. Immunoprecipitation and western blotting experiments confirm the interaction of JNK1 with Sfpq/Nono and demonstrate that it is RNA dependent. Confocal microscopy and subcellular fractionation indicates that JNK1 associates with neuronal granule proteins in the cytosol of PC12 cells, primary cortical neurons and P19-neuronal cells. Finally, siRNA experiments confirm that Sfpq is necessary for neuronal outgrowth in PC12 cells and that it is most likely acting in the same pathway as JNK. In summary, our data indicate that the interaction of JNK1 with transport granule proteins in the cytosol of differentiating neurons plays an important role during neuronal development.