Spinocerebellar ataxia 14 (SCA14) is a rare autosomal dominant neurodegenerative disease caused by mutations in protein kinase C gamma gene (PRKCG, PKCγ protein) leading to motor deficits and cognitive decline. PKCγ is a signalling protein strongly expressed in Purkinje cells (PCs) of the cerebellum and is known to be involved in the regulation of synapse formation and PC dendritic development. The effects of PKCγ are mediated by phosphorylation of target proteins which regulate cytoskeleton dynamics playing a critical role in dendritic development. However, the interaction of PKCγ with cytoskeletal regulators is still poorly understood. In this project, we are taking advantage of a PKCγ mutant mouse line (A24E), expressing a constitutively active PKCγ and causing Spinocerebellar ataxia 14 (SCA14)-like phenotype, to identify PKCγ molecular targets crucial for PC development. Using proteomic and phospho-proteomic analyses we compared the expression and phosphorylation of potential target proteins in normal mice with those of mice having PCs with a constitutively active PKCγ. We identified Metastasis suppressor protein 1 (Mtss1) as a potential PKCγ target showing a significant increase in phosphorylation of S265 and S266 phospho-sites according to phospho-proteomics data. The function and the involvement of Mtss1 in PKCγ signalling were explored in dissociated cerebellar cultures and organotypic slice cultures, focusing on the morphological analyses of PC dendritic arbours with changed Mtss1 expression and activity. The results of the current analyses will be presented at the meeting and indicate the important role of Mtss1 in PC dendritic development.