Author:

Keywords:

Science & Technology, Life Sciences & Biomedicine, Clinical Neurology, Neurosciences, Pathology, Neurosciences & Neurology, ataxia, axonal swellings, multifunctional protein-2, beta-oxidation, peroxisomes, Purkinje cell, MOUSE MODEL, NERVOUS-SYSTEM, MUTANT MOUSE, C DISEASE, DEGENERATION, EXPRESSION, MICE, MUTATIONS, AUTOPHAGY, DEATH, β-oxidation, Aging, Animals, Astrocytes, Axons, Cerebellar Ataxia, Disease Models, Animal, Gliosis, Mice, Transgenic, Microglia, Neurodegenerative Diseases, Peroxisomal Disorders, Peroxisomal Multifunctional Protein-2, Purkinje Cells, 1103 Clinical Sciences, 1109 Neurosciences, Neurology & Neurosurgery, 3202 Clinical sciences, 3209 Neurosciences

Abstract:

Background: Peroxisomes play a crucial role in normal neurodevelopment and in the maintenance of the adult brain. This depends largely on intact peroxisomal β-oxidation given the similarities in pathologies between peroxisome biogenesis disorders and deficiency of multifunctional protein-2 (MFP2), the central enzyme of this pathway. Recently, adult patients diagnosed with cerebellar ataxia were shown to have mild mutations in the MFP2 gene, hydroxy-steroid dehydrogenase (17 beta) type 4 (HSD17B4). Cerebellar atrophy also develops in MFP2 deficient mice but the cellular origin of the degeneration is unexplored. Methods: In order to investigate whether peroxisomal β-oxidation is essential within Purkinje cells, the sole output neurons of the cerebellum, we generated and characterized a mouse model with Purkinje cell selective deletion of the MFP2 gene. Results: We show that selective loss of MFP2 from mature cerebellar Purkinje neurons causes a late-onset motor phenotype and progressive Purkinje cell degeneration, thereby mimicking ataxia and cerebellar deterioration in patients with mild HSD17B4 mutations. We demonstrate that swellings on Purkinje cell axons coincide with ataxic behavior and precede neurodegeneration. Loss of Purkinje cells occurs in a characteristic banded pattern, proceeds in an anterior to posterior fashion and is accompanied by progressive astro- and microgliosis. Conclusions: These data prove that the peroxisomal β-oxidation pathway is required within Purkinje neurons to maintain their axonal integrity, independent of glial dysfunction.