RESUMO
Variants at the GBA locus, encoding glucocerebrosidase, are the strongest common genetic risk factor for Parkinson's disease (PD). To understand GBA-related disease mechanisms, we use a multi-part-enrichment proteomics and post-translational modification (PTM) workflow, identifying large numbers of dysregulated proteins and PTMs in heterozygous GBA-N370S PD patient induced pluripotent stem cell (iPSC) dopamine neurons. Alterations in glycosylation status show disturbances in the autophagy-lysosomal pathway, which concur with upstream perturbations in mammalian target of rapamycin (mTOR) activation in GBA-PD neurons. Several native and modified proteins encoded by PD-associated genes are dysregulated in GBA-PD neurons. Integrated pathway analysis reveals impaired neuritogenesis in GBA-PD neurons and identify tau as a key pathway mediator. Functional assays confirm neurite outgrowth deficits and identify impaired mitochondrial movement in GBA-PD neurons. Furthermore, pharmacological rescue of glucocerebrosidase activity in GBA-PD neurons improves the neurite outgrowth deficit. Overall, this study demonstrates the potential of PTMomics to elucidate neurodegeneration-associated pathways and potential drug targets in complex disease models.
Assuntos
Doença de Parkinson , Humanos , Neurônios Dopaminérgicos/metabolismo , Glucosilceramidase/genética , Glucosilceramidase/metabolismo , Mutação , Crescimento Neuronal , Doença de Parkinson/genética , Doença de Parkinson/metabolismo , Processamento de Proteína Pós-Traducional , ProteômicaRESUMO
Frontotemporal dementia type 3 (FTD3), caused by a point mutation in the charged multivesicular body protein 2B (CHMP2B), affects mitochondrial ultrastructure and the endolysosomal pathway in neurons. To dissect the astrocyte-specific impact of mutant CHMP2B expression, we generated astrocytes from human induced pluripotent stem cells (hiPSCs) and confirmed our findings in CHMP2B mutant mice. Our data provide mechanistic insights into how defective autophagy causes perturbed mitochondrial dynamics with impaired glycolysis, increased reactive oxygen species, and elongated mitochondrial morphology, indicating increased mitochondrial fusion in FTD3 astrocytes. This shift in astrocyte homeostasis triggers a reactive astrocyte phenotype and increased release of toxic cytokines, which accumulate in nuclear factor kappa b (NF-κB) pathway activation with increased production of CHF, LCN2, and C3 causing neurodegeneration.
Assuntos
Astrócitos/metabolismo , Autofagia/genética , Complexos Endossomais de Distribuição Requeridos para Transporte/genética , Demência Frontotemporal/genética , Predisposição Genética para Doença/genética , Mutação , Animais , Astrócitos/citologia , Diferenciação Celular/genética , Células Cultivadas , Complexos Endossomais de Distribuição Requeridos para Transporte/metabolismo , Demência Frontotemporal/metabolismo , Perfilação da Expressão Gênica/métodos , Glicólise/genética , Homeostase/genética , Humanos , Células-Tronco Pluripotentes Induzidas/metabolismo , Camundongos , Mitocôndrias/genética , Mitocôndrias/metabolismo , RNA-Seq/métodos , Transdução de Sinais/genéticaRESUMO
PARK2 (parkin) mutations cause early-onset Parkinson's disease (PD). Parkin is an ubiquitin E3 ligase that participates in several cellular functions, including mitochondrial homeostasis. However, the specific metabolomic changes caused by parkin depletion remain unknown. Here, we used isogenic human induced pluripotent stem cells (iPSCs) with and without PARK2 knockout (KO) to investigate the effect of parkin loss of function by comparative metabolomics supplemented with ultrastructural and functional analyses. PARK2 KO neurons displayed increased tricarboxylic acid (TCA) cycle activity, perturbed mitochondrial ultrastructure, ATP depletion, and dysregulation of glycolysis and carnitine metabolism. These perturbations were combined with increased oxidative stress and a decreased anti-oxidative response. Key findings for PARK2 KO cells were confirmed using patient-specific iPSC-derived neurons. Overall, our data describe a unique metabolomic profile associated with parkin dysfunction and show that combining metabolomics with an iPSC-derived dopaminergic neuronal model of PD is a valuable approach to obtain novel insight into the disease pathogenesis.
Assuntos
Neurônios Dopaminérgicos/metabolismo , Metabolismo Energético , Células-Tronco Pluripotentes Induzidas/metabolismo , Metaboloma , Mitocôndrias/metabolismo , Doença de Parkinson/metabolismo , Ubiquitina-Proteína Ligases/metabolismo , Trifosfato de Adenosina/metabolismo , Ciclo do Ácido Cítrico , Técnicas de Inativação de Genes/métodos , Glicólise , Humanos , Redes e Vias Metabólicas , Mitocôndrias/ultraestrutura , Mutação , Estresse Oxidativo , Doença de Parkinson/genética , Ubiquitina-Proteína Ligases/genéticaRESUMO
The protein parkin, encoded by the PARK2 gene, is vital for mitochondrial homeostasis, and although it has been implicated in Parkinson's disease (PD), the disease mechanisms remain unclear. We have applied mass spectrometry-based proteomics to investigate the effects of parkin dysfunction on the mitochondrial proteome in human isogenic induced pluripotent stem cell-derived neurons with and without PARK2 knockout (KO). The proteomic analysis quantified nearly 60% of all mitochondrial proteins, 119 of which were dysregulated in neurons with PARK2 KO. The protein changes indicated disturbances in oxidative stress defense, mitochondrial respiration and morphology, cell cycle control, and cell viability. Structural and functional analyses revealed an increase in mitochondrial area and the presence of elongated mitochondria as well as impaired glycolysis and lactate-supported respiration, leading to an impaired cell survival in PARK2 KO neurons. This adds valuable insight into the effect of parkin dysfunction in human neurons and provides knowledge of disease-related pathways that can potentially be targeted for therapeutic intervention.
