Subcellular, biochemical and biophysical alterations in two glial cell models of ARSACS

Abstract

Autosomal recessive spastic ataxia of Charlevoix-Saguenay (ARSACS) is a developmental and degenerative disorder caused by loss-of-function mutations in the gene that codifies for the sacsin chaperone. Sacsin was initially described as a neuronal protein but is found in various cell types, including astroglial, microglial, kidney, and skin cell lines. We and others have shown that virtually all cell and animal models of ARSACS show disruption of intermediate filament (IF) cytoskeleton and organelle distribution. This article extends previous observations from our lab on the C6 astroglial-like model and describes the development and characterization of a new human microglial cell model based on HMC3 cells. HMC3 cells knocked out for sacsin show similar alterations to C6 astroglial-like cells: aberrant distribution of IF network and organelles, downregulation of developmental transcription factors STAT3 and Smad1, and alterations in autophagy machinery and markers of intracellular stress, resulting in morphological changes. Our results extend previous observations suggesting a possible role for glial cells in ARSACS and provide new tools to understand the glial-specific mechanisms involved in this pathology.