EN
Zipcode Binding Protein 1 (ZBP1) is one of proteins involved in local translation, a mechanism present in various cell types. In neurons,processes coordinated by ZBP1 are indispensable for proper axonal growth cone and spine formation, as well as dendritic arborization. Recently we also showed that ZBP1-dependent dendritic transport of b-actin mRNA and its local translation is needed for dendritic tree arborization. We also proved that phosphorylation of ZBP1 by Src kinase is important for this process. Now we demonstrate that ZBP1 is effectively phosphorylated in vitro by mTOR kinase. We took advantage of recently published information regarding potential mTOR-dependent phosphorylation sites in ZBP1, i.e. Ser181 (Dai et al. 2011), and examined role of this phosphorylation in (1) dendritic arborization and (2) cellular distribution of ZBP1. To address these questions, we constructed non-phosphorable (S181A) and phosphomimicking (S181E) mutants of ZBP1 fused to GFP. We observed that S181E but not S181A reversed morphological deficits caused by ZBP1 knockdown. Another observation was that distribution along the dendrites of non-phosphorable mutant was more even that distribution of wild type ZBP1, which is denser at the dendritic branching points. Thus we concluded that Ser181 phosphorylation is involved in ZBP1 functions during dendritic growth. This research has been supported by National Science Center (NCN) grant 2011/01/N/NZ3/05405.