Sex specific disruptions in Protein Kinase Cγ signaling in a mouse model of Spinocerebellar Ataxia Type 14

Abstract

Spinocerebellar Ataxia Type 14 (SCA14) is an autosomal dominant neurodegenerative disease caused by mutations in the gene encoding protein kinase C gamma (PKC{gamma}), a Ca2+/diacylglycerol (DG)-dependent serine/threonine kinase dominantly expressed in cerebellar Purkinje cells. These mutations impair autoinhibitory constraints to increase the basal activity of the kinase, resulting in deficits in the cerebellum that are not observed upon simple deletion of the gene, and severe ataxia. To better understand the phenotypic impact of aberrant PKC{gamma} signaling in disease pathology, we developed a knock-in murine model of the SCA14 mutation {Delta}F48 in PKC{gamma}. This fully penetrant mutation is severe in humans and is mechanistically informative as it has high basal activity but is unresponsive to agonist stimulation. Genetic, behavioral, and molecular testing revealed that {Delta}F48 PKC{gamma} SCA14 mice have ataxia related phenotypes and an altered cerebellar phosphoproteome, effects that are more severe in male mice. Analysis of existing human data reveal that SCA14 has a significantly earlier age of onset for males compared with females. Our data from this clinically relevant mutation suggest that enhanced basal activity of PKC{gamma} is necessary and sufficient to cause ataxia and that treatment strategies to modulate aberrant PKC{gamma} may be particularly beneficial in males. SummaryNew mouse model of Spinocerebellar Ataxia Type 14 containing a clinically relevant mutation in PKC{gamma} identified underlying drivers of the disease and neuroprotection in females.