RESUMO
The physical interactome of a protein can be altered upon perturbation, modulating cell physiology and contributing to disease. Identifying interactome differences of normal and disease states of proteins could help understand disease mechanisms, but current methods do not pinpoint structure-specific PPIs and interaction interfaces proteome-wide. We used limited proteolysis-mass spectrometry (LiP-MS) to screen for structure-specific PPIs by probing for protease susceptibility changes of proteins in cellular extracts upon treatment with specific structural states of a protein. We first demonstrated that LiP-MS detects well-characterized PPIs, including antibody-target protein interactions and interactions with membrane proteins, and that it pinpoints interfaces, including epitopes. We then applied the approach to study conformation-specific interactors of the Parkinson's disease hallmark protein alpha-synuclein (aSyn). We identified known interactors of aSyn monomer and amyloid fibrils and provide a resource of novel putative conformation-specific aSyn interactors for validation in further studies. We also used our approach on GDP- and GTP-bound forms of two Rab GTPases, showing detection of differential candidate interactors of conformationally similar proteins. This approach is applicable to screen for structure-specific interactomes of any protein, including posttranslationally modified and unmodified, or metabolite-bound and unbound protein states.
Assuntos
alfa-Sinucleína , Humanos , alfa-Sinucleína/metabolismo , alfa-Sinucleína/química , Mapeamento de Interação de Proteínas , Espectrometria de Massas , Ligação Proteica , Proteólise , Doença de Parkinson/metabolismo , Proteínas rab de Ligação ao GTP/metabolismo , Mapas de Interação de Proteínas , Conformação Proteica , Amiloide/metabolismo , Amiloide/química , Proteoma/metabolismoRESUMO
Alzheimer's disease (AD) is an age-related neurodegenerative condition and the most common type of dementia, characterised by pathological accumulation of extracellular plaques and intracellular neurofibrillary tangles that mainly consist of amyloid-ß (Aß) and hyperphosphorylated tau aggregates, respectively. Previous studies in mouse models with a targeted knock-out of the microtubule-associated protein tau (Mapt) gene demonstrated that Aß-driven toxicity is tau-dependent. However, human cellular models with chronic tau lowering remain unexplored. In this study, we generated stable tau-depleted human induced pluripotent stem cell (iPSC) isogenic panels from two healthy individuals using CRISPR-Cas9 technology. We then differentiated these iPSCs into cortical neurons in vitro in co-culture with primary rat cortical astrocytes before conducting electrophysiological and imaging experiments for a wide range of disease-relevant phenotypes. Both AD brain derived and recombinant Aß were used in this study to elicit toxic responses from the iPSC-derived cortical neurons. We showed that tau depletion in human iPSC-derived cortical neurons caused considerable reductions in neuronal activity without affecting synaptic density. We also observed neurite outgrowth impairments in two of the tau-depleted lines used. Finally, tau depletion protected neurons from adverse effects by mitigating the impact of exogenous Aß-induced hyperactivity, deficits in retrograde axonal transport of mitochondria, and neurodegeneration. Our study established stable human iPSC isogenic panels with chronic tau depletion from two healthy individuals. Cortical neurons derived from these iPSC lines showed that tau is essential in Aß-driven hyperactivity, axonal transport deficits, and neurodegeneration, consistent with studies conducted in Mapt-/- mouse models. These findings highlight the protective effects of chronic tau lowering strategies in AD pathogenesis and reinforce the potential in clinical settings. The tau-depleted human iPSC models can now be applied at scale to investigate the involvement of tau in disease-relevant pathways and cell types.
RESUMO
Parkinson's disease (PD) is the second most common neurodegenerative disorder and a central role for α-synuclein (αSyn; SNCA) in disease aetiology has been proposed based on genetics and neuropathology. To better understand the pathological mechanisms of αSyn, we generated induced pluripotent stem cells (iPSCs) from healthy individuals and PD patients carrying the A53T SNCA mutation or a triplication of the SNCA locus and differentiated them into dopaminergic neurons (DAns). iPSC-derived DAn from PD patients carrying either mutation showed increased intracellular αSyn accumulation, and DAns from patients carrying the SNCA triplication displayed oligomeric αSyn pathology and elevated αSyn extracellular release. Transcriptomic analysis of purified DAns revealed perturbations in expression of genes linked to mitochondrial function, consistent with observed reduction in mitochondrial respiration, impairment in mitochondrial membrane potential, aberrant mitochondrial morphology and decreased levels of phosphorylated DRP1Ser616. Parkinson's iPSC-derived DAns showed increased endoplasmic reticulum stress and impairments in cholesterol and lipid homeostasis. Together, these data show a correlation between αSyn cellular pathology and deficits in metabolic and cellular bioenergetics in the pathology of PD.
Assuntos
Neurônios Dopaminérgicos/metabolismo , Células-Tronco Pluripotentes Induzidas/metabolismo , Mitocôndrias/metabolismo , Doença de Parkinson/genética , alfa-Sinucleína/genética , Diferenciação Celular , Dinaminas/metabolismo , Estresse do Retículo Endoplasmático/genética , Metabolismo Energético/genética , Humanos , Metabolismo dos Lipídeos/genética , Potencial da Membrana Mitocondrial , Mitocôndrias/ultraestrutura , Mutação , Doença de Parkinson/metabolismo , RNA-Seq , Sinucleinopatias/metabolismo , alfa-Sinucleína/metabolismoRESUMO
Non-neuronal cell types such as astrocytes can contribute to Parkinson's disease (PD) pathology. The G2019S mutation in leucine-rich repeat kinase 2 (LRRK2) is one of the most common known causes of familial PD. To characterize its effect on astrocytes, we developed a protocol to produce midbrain-patterned astrocytes from human induced pluripotent stem cells (iPSCs) derived from PD LRRK2 G2019S patients and healthy controls. RNA sequencing analysis revealed the downregulation of genes involved in the extracellular matrix in PD cases. In particular, transforming growth factor beta 1 (TGFB1), which has been shown to inhibit microglial inflammatory response in a rat model of PD, and matrix metallopeptidase 2 (MMP2), which has been shown to degrade α-synuclein aggregates, were found to be down-regulated in LRRK2 G2019S astrocytes. Our findings suggest that midbrain astrocytes carrying the LRRK2 G2019S mutation may have reduced neuroprotective capacity and may contribute to the development of PD pathology.
Assuntos
Astrócitos/metabolismo , Metaloproteinase 2 da Matriz/biossíntese , Doença de Parkinson/metabolismo , Fator de Crescimento Transformador beta1/biossíntese , Idoso , Regulação para Baixo , Feminino , Humanos , Células-Tronco Pluripotentes Induzidas/metabolismo , Serina-Treonina Proteína Quinase-2 com Repetições Ricas em Leucina/genética , Masculino , Pessoa de Meia-Idade , Mutação , Doença de Parkinson/genética , Análise de Sequência de RNARESUMO
BACKGROUND: Mutations in LRRK2 are the most common cause of autosomal dominant Parkinson's disease, and the relevance of LRRK2 to the sporadic form of the disease is becoming ever more apparent. It is therefore essential that studies are conducted to improve our understanding of the cellular role of this protein. Here we use multiple models and techniques to identify the pathways through which LRRK2 mutations may lead to the development of Parkinson's disease. METHODS: A novel integrated transcriptomics and proteomics approach was used to identify pathways that were significantly altered in iPSC-derived dopaminergic neurons carrying the LRRK2-G2019S mutation. Western blotting, immunostaining and functional assays including FM1-43 analysis of synaptic vesicle endocytosis were performed to confirm these findings in iPSC-derived dopaminergic neuronal cultures carrying either the LRRK2-G2019S or the LRRK2-R1441C mutation, and LRRK2 BAC transgenic rats, and post-mortem human brain tissue from LRRK2-G2019S patients. RESULTS: Our integrated -omics analysis revealed highly significant dysregulation of the endocytic pathway in iPSC-derived dopaminergic neurons carrying the LRRK2-G2019S mutation. Western blot analysis confirmed that key endocytic proteins including endophilin I-III, dynamin-1, and various RAB proteins were downregulated in these cultures and in cultures carrying the LRRK2-R1441C mutation, compared with controls. We also found changes in expression of 25 RAB proteins. Changes in endocytic protein expression led to a functional impairment in clathrin-mediated synaptic vesicle endocytosis. Further to this, we found that the endocytic pathway was also perturbed in striatal tissue of aged LRRK2 BAC transgenic rats overexpressing either the LRRK2 wildtype, LRRK2-R1441C or LRRK2-G2019S transgenes. Finally, we found that clathrin heavy chain and endophilin I-III levels are increased in human post-mortem tissue from LRRK2-G2019S patients compared with controls. CONCLUSIONS: Our study demonstrates extensive alterations across the endocytic pathway associated with LRRK2 mutations in iPSC-derived dopaminergic neurons and BAC transgenic rats, as well as in post-mortem brain tissue from PD patients carrying a LRRK2 mutation. In particular, we find evidence of disrupted clathrin-mediated endocytosis and suggest that LRRK2-mediated PD pathogenesis may arise through dysregulation of this process.
Assuntos
Neurônios Dopaminérgicos/metabolismo , Endocitose/genética , Serina-Treonina Proteína Quinase-2 com Repetições Ricas em Leucina/genética , Mutação , Animais , Perfilação da Expressão Gênica , Humanos , Serina-Treonina Proteína Quinase-2 com Repetições Ricas em Leucina/metabolismo , Proteômica , Ratos , Ratos Transgênicos , Vesículas Sinápticas/genéticaRESUMO
While induced pluripotent stem cell (iPSC) technologies enable the study of inaccessible patient cell types, cellular heterogeneity can confound the comparison of gene expression profiles between iPSC-derived cell lines. Here, we purified iPSC-derived human dopaminergic neurons (DaNs) using the intracellular marker, tyrosine hydroxylase. Once purified, the transcriptomic profiles of iPSC-derived DaNs appear remarkably similar to profiles obtained from mature post-mortem DaNs. Comparison of the profiles of purified iPSC-derived DaNs derived from Parkinson's disease (PD) patients carrying LRRK2 G2019S variants to controls identified significant functional convergence amongst differentially-expressed (DE) genes. The PD LRRK2-G2019S associated profile was positively matched with expression changes induced by the Parkinsonian neurotoxin rotenone and opposed by those induced by clioquinol, a compound with demonstrated therapeutic efficacy in multiple PD models. No functional convergence amongst DE genes was observed following a similar comparison using non-purified iPSC-derived DaN-containing populations, with cellular heterogeneity appearing a greater confound than genotypic background.
Assuntos
Células-Tronco Pluripotentes Induzidas/efeitos dos fármacos , Serina-Treonina Proteína Quinase-2 com Repetições Ricas em Leucina/genética , Doença de Parkinson/tratamento farmacológico , Transcriptoma/genética , Autopsia , Células Cultivadas , Clioquinol/administração & dosagem , Dopamina/genética , Neurônios Dopaminérgicos/efeitos dos fármacos , Neurônios Dopaminérgicos/metabolismo , Neurônios Dopaminérgicos/patologia , Perfilação da Expressão Gênica/métodos , Regulação da Expressão Gênica/efeitos dos fármacos , Humanos , Células-Tronco Pluripotentes Induzidas/metabolismo , Serina-Treonina Proteína Quinase-2 com Repetições Ricas em Leucina/biossíntese , Mutação , Doença de Parkinson/genética , Doença de Parkinson/patologia , Rotenona/metabolismo , Rotenona/toxicidade , Transcriptoma/efeitos dos fármacosRESUMO
Induced pluripotent stem cell (iPSC)-derived cortical neurons potentially present a powerful new model to understand corticogenesis and neurological disease. Previous work has established that differentiation protocols can produce cortical neurons, but little has been done to characterize these at cellular resolution. In particular, it is unclear to what extent in vitro two-dimensional, relatively disordered culture conditions recapitulate the development of in vivo cortical layer identity. Single-cell multiplex reverse transcriptase-quantitative polymerase chain reaction (RT-qPCR) was used to interrogate the expression of genes previously implicated in cortical layer or phenotypic identity in individual cells. Totally, 93.6% of single cells derived from iPSCs expressed genes indicative of neuronal identity. High proportions of single neurons derived from iPSCs expressed glutamatergic receptors and synaptic genes. And, 68.4% of iPSC-derived neurons expressing at least one layer marker could be assigned to a laminar identity using canonical cortical layer marker genes. We compared single-cell RNA-seq of our iPSC-derived neurons to available single-cell RNA-seq data from human fetal and adult brain and found that iPSC-derived cortical neurons closely resembled primary fetal brain cells. Unexpectedly, a subpopulation of iPSC-derived neurons co-expressed canonical fetal deep and upper cortical layer markers. However, this appeared to be concordant with data from primary cells. Our results therefore provide reassurance that iPSC-derived cortical neurons are highly similar to primary cortical neurons at the level of single cells but suggest that current layer markers, although effective, may not be able to disambiguate cortical layer identity in all cells.
Assuntos
Córtex Cerebral/metabolismo , Células-Tronco Pluripotentes Induzidas/metabolismo , Proteínas do Tecido Nervoso/metabolismo , Neurogênese/genética , Neurônios/metabolismo , Transcriptoma , Adulto , Idoso , Biomarcadores/metabolismo , Diferenciação Celular , Linhagem Celular , Córtex Cerebral/citologia , Feminino , Feto , Fibroblastos/citologia , Fibroblastos/metabolismo , Perfilação da Expressão Gênica , Regulação da Expressão Gênica no Desenvolvimento , Humanos , Células-Tronco Pluripotentes Induzidas/citologia , Proteínas do Tecido Nervoso/genética , Neurônios/citologia , Reação em Cadeia da Polimerase em Tempo Real , Receptores de Glutamato/genética , Receptores de Glutamato/metabolismo , Análise de Sequência de RNA , Análise de Célula ÚnicaRESUMO
The establishment of a reliable model for the study of Purkinje cells in vitro is of particular importance, given their central role in cerebellar function and pathology. Recent advances in induced pluripotent stem cell (iPSC) technology offer the opportunity to generate multiple neuronal subtypes for study in vitro. However, to date, only a handful of studies have generated Purkinje cells from human pluripotent stem cells, with most of these protocols proving challenging to reproduce. Here, we describe a simplified method for the reproducible generation of Purkinje cells from human iPSCs. After 21 days of treatment with factors selected to mimic the self-inductive properties of the isthmic organiser-insulin, fibroblast growth factor 2 (FGF2), and the transforming growth factor ß (TGFß)-receptor blocker SB431542-hiPSCs could be induced to form En1-positive cerebellar progenitors at efficiencies of up to 90%. By day 35 of differentiation, subpopulations of cells representative of the two cerebellar germinal zones, the rhombic lip (Atoh1-positive) and ventricular zone (Ptf1a-positive), could be identified, with the latter giving rise to cells positive for Purkinje cell progenitor-specific markers, including Lhx5, Kirrel2, Olig2 and Skor2. Further maturation was observed following dissociation and co-culture of these cerebellar progenitors with mouse cerebellar cells, with 10% of human cells staining positive for the Purkinje cell marker calbindin by day 70 of differentiation. This protocol, which incorporates modifications designed to enhance cell survival and maturation and improve the ease of handling, should serve to make existing models more accessible, in order to enable future advances in the field.
Assuntos
Técnicas de Cultura de Células/métodos , Células-Tronco Pluripotentes Induzidas/fisiologia , Neurogênese , Células de Purkinje/fisiologia , Idoso , Animais , Técnicas de Cocultura , Feminino , Humanos , Células-Tronco Pluripotentes Induzidas/citologia , Masculino , Camundongos Endogâmicos C57BL , Pessoa de Meia-Idade , Neurogênese/fisiologia , Células de Purkinje/citologia , Alicerces TeciduaisRESUMO
The U1 small nuclear (sn)RNA (U1) is a multifunctional ncRNA, known for its pivotal role in pre-mRNA splicing and regulation of RNA 3' end processing events. We recently demonstrated that a new class of human U1-like snRNAs, the variant (v)U1 snRNAs (vU1s), also participate in pre-mRNA processing events. In this study, we show that several human vU1 genes are specifically upregulated in stem cells and participate in the regulation of cell fate decisions. Significantly, ectopic expression of vU1 genes in human skin fibroblasts leads to increases in levels of key pluripotent stem cell mRNA markers, including NANOG and SOX2. These results reveal an important role for vU1s in the control of key regulatory networks orchestrating the transitions between stem cell maintenance and differentiation. Moreover, vU1 expression varies inversely with U1 expression during differentiation and cell re-programming and this pattern of expression is specifically de-regulated in iPSC-derived motor neurons from Spinal Muscular Atrophy (SMA) type 1 patient's. Accordingly, we suggest that an imbalance in the vU1/U1 ratio, rather than an overall reduction in Uridyl-rich (U)-snRNAs, may contribute to the specific neuromuscular disease phenotype associated with SMA.
Assuntos
Células-Tronco Embrionárias Humanas/fisiologia , Células-Tronco Pluripotentes Induzidas/fisiologia , RNA Nuclear Pequeno/genética , Células Cultivadas , Regulação da Expressão Gênica , Humanos , RNA Nuclear Pequeno/metabolismo , Atrofias Musculares Espinais da Infância/genética , Transcriptoma , Regulação para CimaRESUMO
Induced pluripotent stem cells have great potential as a human model system in regenerative medicine, disease modeling, and drug screening. However, their use in medical research is hampered by laborious reprogramming procedures that yield low numbers of induced pluripotent stem cells. For further applications in research, only the best, competent clones should be used. The standard assays for pluripotency are based on genomic approaches, which take up to 1 week to perform and incur significant cost. Therefore, there is a need for a rapid and cost-effective assay able to distinguish between pluripotent and nonpluripotent cells. Here, we describe a novel multiplexed, high-throughput, and sensitive peptide-based multiple reaction monitoring mass spectrometry assay, allowing for the identification and absolute quantitation of multiple core transcription factors and pluripotency markers. This assay provides simpler and high-throughput classification into either pluripotent or nonpluripotent cells in 7 min analysis while being more cost-effective than conventional genomic tests.
Assuntos
Células-Tronco Pluripotentes Induzidas/metabolismo , Proteoma/análise , Proteômica , Diferenciação Celular , Células Cultivadas , Reprogramação Celular , Corpos Embrioides/citologia , Corpos Embrioides/metabolismo , Humanos , Células-Tronco Pluripotentes Induzidas/citologia , Espectrometria de Massas/métodos , Proteoma/metabolismo , Pele/citologia , Fatores de Transcrição/análise , Fatores de Transcrição/metabolismoRESUMO
An expanded hexanucleotide repeat in a noncoding region of the C9orf72 gene is a major cause of amyotrophic lateral sclerosis (ALS), accounting for up to 40% of familial cases and 7% of sporadic ALS in European populations. We have generated induced pluripotent stem cells (iPSCs) from fibroblasts of patients carrying C9orf72 hexanucleotide expansions, differentiated these to functional motor and cortical neurons, and performed an extensive phenotypic characterization. In C9orf72 iPSC-derived motor neurons, decreased cell survival is correlated with dysfunction in Ca(2+) homeostasis, reduced levels of the antiapoptotic protein Bcl-2, increased endoplasmic reticulum (ER) stress, and reduced mitochondrial membrane potential. Furthermore, C9orf72 motor neurons, and also cortical neurons, show evidence of abnormal protein aggregation and stress granule formation. This study is an extensive characterization of iPSC-derived motor neurons as cellular models of ALS carrying C9orf72 hexanucleotide repeats, which describes a novel pathogenic link between C9orf72 mutations, dysregulation of calcium signaling, and altered proteostasis and provides a potential pharmacological target for the treatment of ALS and the related neurodegenerative disease frontotemporal dementia. Stem Cells 2016;34:2063-2078.
Assuntos
Esclerose Lateral Amiotrófica/patologia , Proteína C9orf72/genética , Cálcio/metabolismo , Expansão das Repetições de DNA/genética , Retículo Endoplasmático/metabolismo , Demência Frontotemporal/patologia , Células-Tronco Pluripotentes Induzidas/metabolismo , Neurônios Motores/metabolismo , Esclerose Lateral Amiotrófica/genética , Apoptose , Caspase 3/metabolismo , Diferenciação Celular , Reprogramação Celular , Córtex Cerebral/patologia , Grânulos Citoplasmáticos/metabolismo , Grânulos Citoplasmáticos/ultraestrutura , Retículo Endoplasmático/ultraestrutura , Fibroblastos/metabolismo , Fibroblastos/patologia , Demência Frontotemporal/genética , Homeostase/genética , Humanos , Mitocôndrias/metabolismo , Mitocôndrias/ultraestrutura , Peptídeos/metabolismo , Agregados Proteicos , Proteínas Proto-Oncogênicas c-bcl-2/metabolismo , RNA/genéticaRESUMO
Parkinson's disease (PD) is characterized by a progressive deterioration of motor and cognitive functions. Although death of dopamine neurons is the hallmark pathology of PD, this is a late-stage disease process preceded by neuronal dysfunction. Here we describe early physiological perturbations in patient-derived induced pluripotent stem cell (iPSC)-dopamine neurons carrying the GBA-N370S mutation, a strong genetic risk factor for PD. GBA-N370S iPSC-dopamine neurons show an early and persistent calcium dysregulation notably at the mitochondria, followed by reduced mitochondrial membrane potential and oxygen consumption rate, indicating mitochondrial failure. With increased neuronal maturity, we observed decreased synaptic function in PD iPSC-dopamine neurons, consistent with the requirement for ATP and calcium to support the increase in electrophysiological activity over time. Our work demonstrates that calcium dyshomeostasis and mitochondrial failure impair the higher electrophysiological activity of mature neurons and may underlie the vulnerability of dopamine neurons in PD.
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
iPSCs (induced pluripotent stem cells) offer an unparalleled opportunity to generate and study physiologically relevant cell types in culture. iPSCs can be generated by reprogramming almost any somatic cell type using pluripotency factors such as Oct4, SOX2, Nanog and Klf4. By reprogramming cells from patients carrying disease-associated mutations, and subsequent differentiation into the cell type of interest, researchers now have the opportunity to study disease-specific cell types which were previously inaccessible. In the case of PD (Parkinson's disease), reprogramming is advancing rapidly, and cell lines have been generated from patients carrying mutations in several disease-associated genes, including SNCA (α-synuclein), PARK2 (parkin), PINK1 (phosphatase and tensin homologue deleted on chromosome 10-induced putative kinase 1), PARK7 (DJ-1) and LRRK2 (leucine-rich repeat kinase 2), as well as idiopathic cases. Functional dopaminergic neurons have been differentiated from these cells and their physiology has been compared with control neurons. Human dopaminergic neurons had been previously inaccessible until post-mortem, when the disease is generally highly progressed into pathology. In comparison, iPSCs provide a living cell model with the potential to study early molecular changes which accumulate in cells and ultimately result in neurodegeneration. Although clear phenotypes have not yet been unambiguously identified in patient-derived dopaminergic neurons, there are suggested aberrations in cellular pathways involved in neurodegeneration. Overall, these cells offer a unique opportunity to study dopaminergic neurons carrying a 'Parkinsonian genome'. The present review discusses the advances in cellular reprogramming technologies and studies that have been carried out on PD-derived iPSCs and differentiated dopaminergic neurons.
Assuntos
Células-Tronco Pluripotentes Induzidas/metabolismo , Modelos Biológicos , Doença de Parkinson/metabolismo , Diferenciação Celular , Neurônios Dopaminérgicos/metabolismo , Neurônios Dopaminérgicos/patologia , Humanos , Fator 4 Semelhante a Kruppel , Doença de Parkinson/patologiaRESUMO
Macrophages are key target cells of Zika virus (ZIKV) infection, implicated as a viral reservoir seeding sanctuary sites such as the central nervous system and testes. This rests on the apparent ability of macrophages to sustain ZIKV replication without experiencing cytopathic effects. ZIKV infection of macrophages triggers an innate immune response involving type I interferons (IFN-I), key antiviral cytokines that play a complex role in ZIKV pathogenesis in animal models. To investigate the functional role of the IFN-I response we generated human induced pluripotent stem cell (iPSC)-derived macrophages from a patient with complete deficiency of IFNAR2, the high affinity IFN-I receptor subunit. Accompanying the profound defect of IFN-I signalling in IFNAR2 deficient iPS-macrophages we observed significantly enhanced ZIKV replication and cell death, revealing the inherent cytopathicity of ZIKV towards macrophages. These observations were recapitulated by genetic and pharmacological ablation of IFN-I signalling in control iPS-macrophages and extended to a model of iPS-microglia. Thus, the capacity of macrophages to support noncytolytic ZIKV replication depends on an equilibrium set by IFN-I, suggesting that innate antiviral responses might counterintuitively promote ZIKV persistence via the maintenance of tissue viral reservoirs relevant to pathogenesis.
Assuntos
Células-Tronco Pluripotentes Induzidas , Infecção por Zika virus , Zika virus , Animais , Humanos , Receptor de Interferon alfa e beta/genética , Microglia/metabolismo , Células-Tronco Pluripotentes Induzidas/metabolismo , Macrófagos/metabolismo , Interferons/farmacologia , Antivirais/uso terapêuticoRESUMO
Most inherited neurodegenerative disorders are incurable, and often only palliative treatment is available. Precision medicine has great potential to address this unmet clinical need. We explored this paradigm in dopamine transporter deficiency syndrome (DTDS), caused by biallelic loss-of-function mutations in SLC6A3, encoding the dopamine transporter (DAT). Patients present with early infantile hyperkinesia, severe progressive childhood parkinsonism, and raised cerebrospinal fluid dopamine metabolites. The absence of effective treatments and relentless disease course frequently leads to death in childhood. Using patient-derived induced pluripotent stem cells (iPSCs), we generated a midbrain dopaminergic (mDA) neuron model of DTDS that exhibited marked impairment of DAT activity, apoptotic neurodegeneration associated with TNFα-mediated inflammation, and dopamine toxicity. Partial restoration of DAT activity by the pharmacochaperone pifithrin-µ was mutation-specific. In contrast, lentiviral gene transfer of wild-type human SLC6A3 complementary DNA restored DAT activity and prevented neurodegeneration in all patient-derived mDA lines. To progress toward clinical translation, we used the knockout mouse model of DTDS that recapitulates human disease, exhibiting parkinsonism features, including tremor, bradykinesia, and premature death. Neonatal intracerebroventricular injection of human SLC6A3 using an adeno-associated virus (AAV) vector provided neuronal expression of human DAT, which ameliorated motor phenotype, life span, and neuronal survival in the substantia nigra and striatum, although off-target neurotoxic effects were seen at higher dosage. These were avoided with stereotactic delivery of AAV2.SLC6A3 gene therapy targeted to the midbrain of adult knockout mice, which rescued both motor phenotype and neurodegeneration, suggesting that targeted AAV gene therapy might be effective for patients with DTDS.
Assuntos
Terapia Genética , Células-Tronco Pluripotentes Induzidas , Transtornos Parkinsonianos , Animais , Modelos Animais de Doenças , Proteínas da Membrana Plasmática de Transporte de Dopamina/genética , Proteínas da Membrana Plasmática de Transporte de Dopamina/metabolismo , Humanos , Células-Tronco Pluripotentes Induzidas/metabolismo , Camundongos , Transtornos Parkinsonianos/genética , Transtornos Parkinsonianos/terapia , Substância Negra/metabolismoRESUMO
Radical S-adenosylmethionine (SAM) domain-containing protein 2 (RSAD2; viperin) is a key enzyme in innate immune responses that is highly expressed in response to viral infection and inflammatory stimuli in many cell types. Recently, it was found that RSAD2 catalyses transformation of cytidine triphosphate (CTP) to its analogue 3'-deoxy-3',4'-didehydro-CTP (ddhCTP). The cellular function of this metabolite is unknown. Here, we analysed the extra- and intracellular metabolite levels in human induced pluripotent stem cell (hiPSC)-derived macrophages using high-resolution LC-MS/MS. The results together with biochemical assays and molecular docking simulations revealed that ddhCTP inhibits the NAD+ -dependent activity of enzymes including that of the housekeeping enzyme glyceraldehyde 3-phosphate dehydrogenase (GAPDH). We propose that ddhCTP regulates cellular metabolism in response to inflammatory stimuli such as viral infection, pointing to a broader function of RSAD2 than previously thought.
Assuntos
Citidina Trifosfato/metabolismo , Macrófagos/enzimologia , NAD/metabolismo , Proteínas/metabolismo , Difosfato de Adenosina/metabolismo , Sítios de Ligação , Gliceraldeído-3-Fosfato Desidrogenase (Fosforiladora)/antagonistas & inibidores , Gliceraldeído-3-Fosfato Desidrogenase (Fosforiladora)/metabolismo , Células HEK293 , Humanos , Células-Tronco Pluripotentes Induzidas/citologia , L-Lactato Desidrogenase/antagonistas & inibidores , L-Lactato Desidrogenase/metabolismo , Macrófagos/citologia , Macrófagos/metabolismo , Malato Desidrogenase/antagonistas & inibidores , Malato Desidrogenase/metabolismo , Modelos Moleculares , Oxirredutases atuantes sobre Doadores de Grupo CH-CHRESUMO
The Parkinson's disease-associated gene, LRRK2, is also associated with immune disorders and infectious disease and is expressed in immune subsets. Here, we characterize a platform for interrogating the expression and function of endogenous LRRK2 in authentic human phagocytes using human induced pluripotent stem cell-derived macrophages and microglia. Endogenous LRRK2 is expressed and upregulated by interferon-γ in these cells, including a 187-kDa cleavage product. Using LRRK2 knockout and G2019S isogenic repair lines, we find that LRRK2 is not involved in initial phagocytic uptake of bioparticles but is recruited to LAMP1+/RAB9+ "maturing" phagosomes, and LRRK2 kinase inhibition enhances its residency at the phagosome. Importantly, LRRK2 is required for RAB8a and RAB10 recruitment to phagosomes, implying that LRRK2 operates at the intersection between phagosome maturation and recycling pathways in these professional phagocytes.
Assuntos
Células-Tronco Pluripotentes Induzidas/metabolismo , Serina-Treonina Proteína Quinase-2 com Repetições Ricas em Leucina/metabolismo , Macrófagos/metabolismo , Fagossomos/metabolismo , Proteínas rab de Ligação ao GTP/metabolismo , Diferenciação Celular , Linhagem Celular , Humanos , Células-Tronco Pluripotentes Induzidas/citologia , Interferon gama/farmacologia , Serina-Treonina Proteína Quinase-2 com Repetições Ricas em Leucina/genética , Macrófagos/citologia , Microglia/citologia , Microglia/efeitos dos fármacos , Microglia/metabolismoRESUMO
TDP-43 dysfunction is common to 97% of amyotrophic lateral sclerosis (ALS) cases, including those with mutations in C9orf72. To investigate how C9ORF72 mutations drive cellular pathology in ALS and to identify convergent mechanisms between C9ORF72 and TARDBP mutations, we analyzed motor neurons (MNs) derived from induced pluripotent stem cells (iPSCs) from patients with ALS. C9ORF72 iPSC-MNs have higher Ca2+ release after depolarization, delayed recovery to baseline after glutamate stimulation, and lower levels of calbindin compared with CRISPR/Cas9 genome-edited controls. TARDBP iPS-derived MNs show high glutamate-induced Ca2+ release. We identify here, by RNA sequencing, that both C9ORF72 and TARDBP iPSC-MNs have upregulation of Ca2+-permeable AMPA and NMDA subunits and impairment of mitochondrial Ca2+ buffering due to an imbalance of MICU1 and MICU2 on the mitochondrial Ca2+ uniporter, indicating that impaired mitochondrial Ca2+ uptake contributes to glutamate excitotoxicity and is a shared feature of MNs with C9ORF72 or TARDBP mutations.
Assuntos
Esclerose Lateral Amiotrófica/genética , Proteína C9orf72/genética , Cálcio/metabolismo , Proteínas de Ligação a DNA/genética , Demência Frontotemporal/genética , Células-Tronco Pluripotentes Induzidas/metabolismo , Neurônios Motores/metabolismo , Esclerose Lateral Amiotrófica/metabolismo , Calbindinas/metabolismo , Canais de Cálcio/metabolismo , Proteínas de Ligação ao Cálcio/metabolismo , Proteínas de Transporte de Cátions/metabolismo , Linhagem Celular , Demência Frontotemporal/metabolismo , Ácido Glutâmico/metabolismo , Humanos , Células-Tronco Pluripotentes Induzidas/citologia , Mitocôndrias/metabolismo , Proteínas de Transporte da Membrana Mitocondrial/metabolismo , Neurônios Motores/citologia , Mutação , Receptores de AMPA/metabolismo , Receptores de N-Metil-D-Aspartato/metabolismoRESUMO
Induced pluripotent stem cell (iPSC)-derived dopamine neurons provide an opportunity to model Parkinson's disease (PD), but neuronal cultures are confounded by asynchronous and heterogeneous appearance of disease phenotypes in vitro. Using high-resolution, single-cell transcriptomic analyses of iPSC-derived dopamine neurons carrying the GBA-N370S PD risk variant, we identified a progressive axis of gene expression variation leading to endoplasmic reticulum stress. Pseudotime analysis of genes differentially expressed (DE) along this axis identified the transcriptional repressor histone deacetylase 4 (HDAC4) as an upstream regulator of disease progression. HDAC4 was mislocalized to the nucleus in PD iPSC-derived dopamine neurons and repressed genes early in the disease axis, leading to late deficits in protein homeostasis. Treatment of iPSC-derived dopamine neurons with HDAC4-modulating compounds upregulated genes early in the DE axis and corrected PD-related cellular phenotypes. Our study demonstrates how single-cell transcriptomics can exploit cellular heterogeneity to reveal disease mechanisms and identify therapeutic targets.