Differential expression of microRNAs from miR-17 family in the cerebellum of mucopolysaccharidosis type I mice.

Mucopolysaccharidosis type I (MPS I) is caused by deficiency of α-l-iduronidase, involved in degradation of glycosaminoglycans. Clinical manifestations are widely variable and patients with severe phenotype present developmental delay and cognitive decline, among other systemic alterations. MPS I patients present secondary accumulation of gangliosides in neuronal cells, besides accumulation of undegraded glycosaminoglycans. Reduction of Neu1 expression has been previously observed in the cerebellum of MPS I mice; to be active, neuraminidase 1 forms the lysosomal multienzyme complex (LMC) with two other proteins, β-galactosidase and protective protein/cathepsin A, involved in stepwise degradation of gangliosides in the lysosomes. In this study, we evaluated relative expression of LMC genes and six possible regulators of their expression, microRNAs (miRNAs) from miR-17 family, which are predicted to target at least two LMC components, in the cerebellum of MPS I mice by real-time PCR. Neu1 was significantly underexpressed in MPS I mice cerebellum, whereas expression of other LMC genes was similar to controls. miR-20b and miR-106b were differentially expressed in MPS I mice, suggesting that they may be involved in the reduction of Neu1 expression; miR-20b-5p was overexpressed while miR-20b-3p and miR-106b-5p were underexpressed. The ratio between miR-20b-3p and miR-20b-5p was also altered in cerebellum of MPS I mice. Confirmation of binding predictions and analysis of the direct role of these miRNAs in the regulation of Neu1 expression could bring important information regarding LMC function. Since miRNAs from miR-17 family are involved in regulation of diverse biological processes, our results also point to new pathogenic cascades to be investigated in MPS I.