Intracerebral Administration of a Ligand-ASO Conjugate Selectively Reduces α-Synuclein Accumulation in Monoamine Neurons of Double Mutant Human A30P*A53T*α-Synuclein Transgenic Mice

α-Synuclein (α-Syn) protein is involved in the pathogenesis of Parkinson’s disease (PD). Point mutations and multiplications of the α-Syn, which encodes the SNCA gene, are correlated with early-onset PD, therefore the reduction in a-Syn synthesis could be a potential therapy for PD if delivered to the key affected neurons. Several experimental strategies for PD have been developed in recent years using oligonucleotide therapeutics. However, some of them have failed or even caused neuronal toxicity. One limiting step in the success of oligonucleotide-based therapeutics is their delivery to the brain compartment, and once there, to selected neuronal populations. Previously, we developed an indatraline-conjugated antisense oligonucleotide (IND-1233-ASO), that selectively reduces α-Syn synthesis in midbrain monoamine neurons of mice, and nonhuman primates. Here, we extended these observations using a transgenic male mouse strain carrying both A30P and A53T mutant human α-Syn (A30P*A53T*α-Syn). We found that A30P*A53T*α-Syn mice at 4–5 months of age showed 3.5-fold increases in human α-Syn expression in dopamine (DA) and norepinephrine (NE) neurons of the substantia nigra pars compacta (SNc) and locus coeruleus (LC), respectively, compared with mouse α-Syn levels. In parallel, transgenic mice exhibited altered nigrostriatal DA neurotransmission, motor alterations, and an anxiety-like phenotype. Intracerebroventricular IND-1233-ASO administration (100 µg/day, 28 days) prevented the α-Syn synthesis and accumulation in the SNc and LC, and recovered DA neurotransmission, although it did not reverse the behavioral phenotype. Therefore, the present therapeutic strategy based on a conjugated ASO could be used for the selective inhibition of α-Syn expression in PD-vulnerable monoamine neurons, showing the benefit of the optimization of ASO molecules as a disease modifying therapy for PD and related α-synucleinopathies.This study was supported by grants SAF2016-75797-R, PID2019-105136RB-100, Retos- Colaboración Subprogram RTC-2015-3309-1, Ministry of Economy and Competitiveness (MINECO) and European Regional Development Fund (ERDF), UE; and CB/07/09/0034 Center for Networked Biomedical Research on Mental Health (CIBERSAM)

Human α-synuclein overexpression in mouse serotonin neurons triggers a depressive-like phenotype. Rescue by oligonucleotide therapy

Anxiety and depression affect 35–50% of patients with Parkinson’s disease (PD), often precede the onset of motor symptoms, and have a negative impact on their quality of life. Dysfunction of the serotonergic (5-HT) system, which regulates mood and emotional pathways, occurs during the premotor phase of PD and contributes to a variety of non-motor symptoms. Furthermore, α-synuclein (α-Syn) aggregates were identified in raphe nuclei in the early stages of the disease. However, there are very few animal models of PD-related neuropsychiatric disorders. Here, we develop a new mouse model of α-synucleinopathy in the 5-HT system that mimics prominent histopathological and neuropsychiatric features of human PD. We showed that adeno-associated virus (AAV5)-induced overexpression of wild-type human α-Syn (h-α-Syn) in raphe 5-HT neurons triggers progressive accumulation, phosphorylation, and aggregation of h-α-Syn protein in the 5-HT system. Specifically, AAV5-injected mice displayed axonal impairment in the output brain regions of raphe neurons, and deficits in brain-derived neurotrophic factor (BDNF) expression and 5-HT neurotransmission, resulting in a depressive-like phenotype. Intracerebroventricular treatment with an indatraline-conjugated antisense oligonucleotide (IND-ASO) for four weeks induced an effective and safe reduction of h-α-Syn synthesis in 5-HT neurons and its accumulation in the forebrain, alleviating early deficits of 5-HT function and improving the behavioural phenotype. Altogether, our findings show that α-synucleinopathy in 5-HT neurons negatively affects brain circuits that control mood and emotions, resembling the expression of neuropsychiatric symptoms occurring at the onset of PD. Early preservation of 5-HT function by reducing α-Syn synthesis/accumulation may alleviate PD-related depressive symptoms.We thank to the Coordenação de Aperfeiçoamento de Nivel Superior (CAPES-PDSE: 19/2016 88881.135527/2016-01), Brazil, for their financial support via a scholarship awarded to C.C.-S. We also thank JAE-Intro Program, CSIC (JAEINT_20_02116), Spain, for their financial support via a scholarship awarded to M.T.-L. This study was supported by grants SAF2016-75797-R, PID2019-105136RB-100, Ministry of Economy and Competitiveness (MINECO) and European Regional Development Fund (ERDF), UE; and CB/07/09/0034 Center for Networked Biomedical Research on Mental Health (CIBERSAM)

Endoplasmic reticulum stress in mouse serotonin and dopamine neurons increases ¿-synuclein oligomerization, resulting in motor deficits and depressive phenotype

Trabajo presentado en el 12 FENS Forum of Neuroscience, celebrado de forma virtual del 11 al 15 de julio de 202

Comparative study for assessment of dopamine neurotransmission and behavioral effects using different models of Parkinson's disease

Trabajo presentado en el 18th National Meeting of the Spanish Society of Neuroscience, celebrado en Santiago de Compostela (España), del 4 al 6 de abril de 201

α-Synucleinopathy in serotonin pathways evokes a depressive phenotype in mice―Reversal by conjugated antisense therapy

Trabajo presentado en el Neurodegenerative Diseases: Biology & Therapeutics, celebrado de forma virtual, del 2 al 4 de diciembre de 202

Human α-synuclein overexpression in mouse raphe nuclei induces Parkinson's disease pathology. Reversal by conjugated antisense therapy

Trabajo presentado en el 18th National Meeting of the Spanish Society of Neuroscience, celebrado en Santiago de Compostela (España), del 4 al 6 de abril de 201

α-Synuclein overexpression in mouse raphe nuclei displays neuropsychiatric symptoms of Parkinson’s disease. Reversal by conjugated antisense therapy

Trabajo presentado en la 7ª edición del Laboratorio de ideas del CIBERSAM: “Inteligencia Artificial en ciencias de la vida”, celebrado en Oviedo (España), los días 13 y 14 de junio de 201

Anti-α-synuclein ASO delivered to monoamine neurons prevents α-synuclein accumulation in a Parkinson's disease-like mouse model and in monkeys

Background: Progressive neuronal death in monoaminergic nuclei and widespread accumulation of α-synuclein are neuropathological hallmarks of Parkinson's disease (PD). Given that α-synuclein may be an early mediator of the pathological cascade that ultimately leads to neurodegeneration, decreased α-synuclein synthesis will abate neurotoxicity if delivered to the key affected neurons. Methods: We used a non-viral gene therapy based on a new indatraline-conjugated antisense oligonucleotide (IND-ASO) to disrupt the α-synuclein mRNA transcription selectively in monoamine neurons of a PD-like mouse model and elderly nonhuman primates. Molecular, cell biology, histological, neurochemical and behavioral assays were performed. Findings: Intracerebroventricular and intranasal IND-ASO administration for four weeks in a mouse model with AAV-mediated wild-type human α-synuclein overexpression in dopamine neurons prevented the synthesis and accumulation of α-synuclein in the connected brain regions, improving dopamine neurotransmission. Likewise, the four-week IND-ASO treatment led to decreased levels of endogenous α-synuclein protein in the midbrain monoamine nuclei of nonhuman primates, which are affected early in PD. Conclusions: : The inhibition of α-synuclein production in dopamine neurons and its accumulation in cortical/striatal projection areas may alleviate the early deficits of dopamine function, showing the high translational value of antisense oligonucleotides as a disease modifying therapy for PD and related synucleinopathies.Grants SAF2016-75797-R, RTC-2014-2812-1 and RTC-2015-3309-1, Ministry of Economy and Competitiveness (MINECO) and European Regional Development Fund (ERDF), UE; Grant ID 9238, Michael J. Fox Foundation; and Centres for Networked Biomedical Research on Mental Health (CIBERSAM), and on Neurodegenerative Diseases (CIBERNED)