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IMPDH2 filaments protect from neurodegeneration in AMPD2 deficiency

ABSTRACT: Metabolic dysregulation is one of the most common causes of pediatric neurodegenerative disorders. However, how the disruption of ubiquitous and essential metabolic pathways predominantly affect neural tissue remains unclear. Here we use mouse models of a childhood neurodegenerative disorder caused by AMPD2 deficiency to study cellular and molecular mechanisms that lead to selective neuronal vulnerability to purine metabolism imbalance. We show that AMPD2 mouse models exhibit predominant degeneration of the hippocampal dentate gyrus, despite a general reduction of brain GTP levels. Neurodegeneration-resistant regions accumulate micron-sized filaments of IMPDH2, the rate limiting enzyme in GTP synthesis, while these filaments are barely detectable in the hippocampal dentate gyrus. Furthermore, we show that IMPDH2 filament disassembly reduces GTP levels and impairs growth of neural progenitor cells derived from individuals with human AMPD2 deficiency. Together, our findings suggest that IMPDH2 polymerization prevents detrimental GTP deprivation, opening the possibility of exploring the induction of IMPDH2 assembly as a therapy for neurodegeneration.

SUBMITTER: Marco Flores-Mendez

PROVIDER: S-SCDT-10_1038-S44319-024-00218-2 | biostudies-other |

REPOSITORIES: biostudies-other

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IMPDH2 filaments protect from neurodegeneration in AMPD2 deficiency

Project description:Metabolic dysregulation is one of the most common causes of pediatric neurodegenerative disorders. However, how the disruption of ubiquitous and essential metabolic pathways predominantly affect neural tissue remains unclear. Here we use a mouse model of AMPD2 deficiency to study cellular and molecular mechanisms that lead to selective neuronal vulnerability to purine metabolism imbalance. We show that AMPD deficiency in mice primarily leads to hippocampal dentate gyrus degeneration despite causing a generalized reduction of brain GTP levels. Remarkably, we uncover that neurodegeneration resistant regions of the hippocampus accumulate micron sized filaments of IMPDH2, the rate limiting enzyme in GTP synthesis. In contrast, IMPDH2 filaments are barely detectable in the dentate gyrus, which show a progressively neuroinflammation and neurodegeneration. Furthermore, using a human AMPD2 neural cell culture model, we show that blocking IMPDH2 polymerization with a dominant negative IMPDH2 variant impairs AMPD2 deficient neural progenitor growth. Together, our findings suggest that IMPDH2 polymerization prevents detrimental GTP deprivation caused by AMPD2 deficiency, providing resistance to neurodegeneration. This data opens the possibility of exploring the involvement of IMPDH2 assembly as a therapeutic intervention for neurodegeneration.

2024-01-16 | GSE253045 | GEO

IMPDH2 filaments protect from neurodegeneration in AMPD2 deficiency

Project description:IMPDH2 filaments protect from neurodegeneration in AMPD2 deficiency

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