Dysregulated autophagy as a new aspect of the molecular pathogenesis of Krabbe disease

Abstract

Krabbe disease (KD) is a childhood leukodystrophy with no cure currently available. KD is due to a deficiency of a lysosomal enzyme called galactosyl-ceramidase (GALC) and is characterized by the accumulation in the nervous system of the sphingolipid psychosine (PSY), whose cytotoxic molecular mechanism is not fully known yet. Here, we study the expression of some fundamental autophagy markers (LC3, p62, and Beclin-1) in a KD murine model [the twitcher (TWI) mouse] by immunohistochemistry and Western blot. Moreover, the autophagy molecular process is also shown in primary fibroblasts from TWI and WT mice, with and without PSY treatment. Data demonstrate that large p62 cytoplasmic aggregates are present in the brain of both early and late symptomatic TWI mice. p62 expression is also upregulated in TWI sciatic nerves compared to that measured for WT nerves. In vitro data suggest that this effect might not be fully PSY-driven. Finally, we investigate in vitro the capability of autophagy inducers (Rapamycin, RAP and Resveratrol, RESV) to reinstate the WT phenotype in TWI cells. We show that RAP administration can partially restore the autophagy markers levels, while RESV cannot, indicating a line along which new therapeutic approaches can be developed.

Keywords: Autophagy; GLD; Globoid cell leukodystrophy; KD; Krabbe disease; LSD; Lysosomal storage disorders; PSY; Psychosine; Rapamycin; p62.