Pacelli, C. | bioRxiv Science

bioRxiv2025

Loss of neurexins disrupts inhibitory connectivity and increases vulnerability of dopamine neurons in culture

Midbrain dopamine (DA) neurons are essential regulators of basal ganglia function. Their axonal structure is intricate, with numerous non-synaptic release sites and fewer synaptic terminals that notably release glutamate or GABA. Despite their significance, the molecular mechanisms governing DA neuron connectivity and neurochemical identity remain poorly understood. We hypothesize that trans-synaptic cell adhesion molecules such as neurexins (Nrxns) regulate the interactions of DA neuron axons with target cells and thereby influence axonal branching and synapse formation by DA neurons. We therefore examined neuronal survival, axonal growth and synapse formation in cultured DA neurons lacking all neurexins (DAT::NrxnsKO). Conditional deletion of all Nrxns in DA neurons revealed that loss of Nrxns does not disrupt the basic development of these neurons or the structure of their axonal terminals, including normal expression of the vesicular monoamine transporter (VMAT2) and the calcium sensor synaptotagmin 1 (Syt1). However, loss of Nrxns affects the survival of DA neurons and their formation of inhibitory synapses, suggesting that Nrxns regulate the axonal connectivity of these neurons.

neuroscience↗

bioRxiv2024

Rescue of lysosomal acid lipase deficiency in mice by rAAV8 liver gene transfer.

Lysosomal acid lipase deficiency (LAL-D) is an autosomal recessive disorder caused by mutations in the LIPA gene, which results in lipid accumulation leading to multi-organ failure. If left untreated, the severe form of LAL-D results in premature death within the first year of life due to failure to thrive and hepatic insufficiency. Enzyme replacement therapy is the only available supportive treatment consisting in weekly systemic injections of recombinant LAL protein. Here, we characterized a novel Lipa-/- mouse model and developed a curative gene therapy treatment based on the in vivo administration of recombinant (r)AAV8 vector encoding the human LIPA transgene under the control of a hepatocyte-specific promoter. We defined the minimal rAAV8 dose required to rescue disease lethality and to correct cholesterol and triglyceride accumulation in multiple organs and blood. Finally, using liver transcriptomic and biochemical analysis, we showed mitochondrial impairment in Lipa-/- mice and its recovery by gene therapy. Overall, our in vivo gene therapy strategy achieves a stable long-term LAL expression sufficient to correct the disease phenotype in the Lipa-/-mouse model and offers a new therapeutic option for LAL-D patients. One Sentence SummaryWeve developed a liver-targeted gene therapy using recombinant AAV8 to effectively cure Lysosomal acid lipase deficiency by correcting lipid accumulation and by normalizing gene expression pattern and mitochondrial function in Lipa-/- mouse model.

molecular biology↗