Project description:Induced pluripotent stem cells (iPSCs) harbor great promise for in vitro generation of disease-relevant cell types, such as mesodiencephalic dopaminergic (mdDA) neurons involved in Parkinson’s disease. Although iPSC-derived midbrain DA neurons have been generated, detailed genetic and epigenetic characterization of such neurons is still lacking. The goal of this study is to examine the authenticity of iPSC-derived DA neurons obtained by established protocols. We FACS-purified mdDA (Pitx3gfp/+) neurons derived from mouse iPSCs and primary mdDA (Pitx3gfp/+) neurons to analyze and compare their genetic and epigenetic features. Although iPSC-derived DA neurons largely adopt characteristics of their in-vivo counterparts, relevant deviations in global gene expression and DNA methylation were found. Hypermethylated genes, mainly involved in neurodevelopment and basic neuronal functions, consequently showed reduced expression levels. Such abnormalities should be addressed as they might affect unambiguous long-term functionality and hamper the potential of iPSC-derived DA neurons for in-vitro disease modeling or cell-based therapy. RRBS methylation maps were generated for iPSCs cells, dopaminergic neurons derived from iPSCs and primary mesodiencephalic dopaminergic neurons
Project description:Dopaminergic neurons participate in fundamental physiological processes and are the cell type primarily affected in Parkinson’s disease (PD). Their analysis is challenging due to the intricate nature of their function, their involvement in diverse neurological processes, their heterogeneity and localization in deep brain regions. Consequently, most of the research on the protein dynamics of dopaminergic neurons has been performed in animal cells ex vivo. Here we use iPSC-derived, human mid-brain specific dopaminergic neurons to study general features of their proteome biology. We cover the proteome to a depth of 9,409 proteins and use dynamic SILAC to measure the half-life of more than 4,300 proteins. Our study provides a workflow and resource for future applications of quantitative proteomics in iPSC-derived human neurons.
Project description:Dopaminergic neurons participate in fundamental physiological processes and are the cell type primarily affected in Parkinson’s disease (PD). Their analysis is challenging due to the intricate nature of their function, their involvement in diverse neurological processes, their heterogeneity and localization in deep brain regions. Consequently, most of the research on the protein dynamics of dopaminergic neurons has been performed in animal cells ex vivo. Here we use iPSC-derived, human mid-brain specific dopaminergic neurons to study general features of their proteome biology. We use dynamic SILAC to measure the half-life of more than 4,300 proteins. We report uniform turnover rates of conserved protein complexes and identify several outliers in the mitochondrial outer membrane and mitophagy pathway. Our study provides a workflow and resource for future applications of quantitative proteomics in iPSC-derived human neurons.
Project description:Human induced pluripotent stem cells (iPSCs) can provide a promising source of midbrain dopaminergic (DA) neurons for cell replacement therapy for Parkinson’s disease. However, iPSC-derived donor cells may inevitably contain tumorigenic or inappropriate cells. Purification of neural progenitor cells or DA neurons as suitable donor cells has been attempted, but the isolation of DA progenitor cells derived from human pluripotent stem cells has so far been unsuccessful. Here we show human iPSC-derived DA progenitor cells can be efficiently isolated by cell sorting using a floor plate marker, Corin. we were able to develop a method for 1) scalable DA neuron induction on human laminin fragment and 2) sorting DA progenitor cells using an anti-Corin antibody. Furthermore, we determined the optimal timing for the cell sorting and transplantation. The grafted cells survived well and functioned as midbrain DA neurons in the 6-OHDA-lesioned rats, and showed minimal risk of tumor formation. The sorting of Corin-positive cells is favorable in terms of both safety and efficiency, and our protocol will contribute to the clinical application of human iPSCs for Parkinson’s disease. Differentiated human iPSC-derived neural progenitors just after sorting (day12 unsorted, day12 Corin+) and dopaminergic progenitors after an aggregation culture (day28 and day42, unsorted and day12-sorted, respectively), and human fetal ventral mesencephalon and dorsal mesencephalon (gestational age of 7.5 weeks) were subjected to RNA extraction and hybrdization on Affymetrix microarrays. Each sample except for human mesencephalon, undifferentiated iPSC, and day12-unsorted, day42-sample has 3 or 4 repeats.
Project description:Although-synuclein is implicated in the pathogenesis of Parkinson’s disease and related disorders, it remains unclear whether specific conformations or levels of-synuclein assemblies are toxic and how they cause progressive loss of human dopaminergic neurons. To address this issue, we used iPSC-derived dopaminergic neurons with -synuclein triplication or controls where endogenous -synuclein was imprinted into synthetic or disease-relevant conformations. We used -synuclein fibrils generated de novo or amplified from homogenates of brains affected with Parkinson’s disease (n=3) or multiple system atrophy (n=5). We found that a 2.5-fold increase in -synuclein levels in -synuclein gene triplication neurons promoted seeded aggregation in a dose and time-dependent fashion, which was associated with a further increase in -synuclein gene expression. Progressive neuronal loss was observed only in -synuclein triplication neurons seeded with brain-amplified fibrils. Transcriptomic analysis and isogenic correction of -synuclein triplication revealed that intraneuronal-synuclein levels solely and sufficiently explained vulnerability to neuronal death. Proximity-dependent biotinylation in living cells identified 56 differentially interacting proteins with endogenously assembled -synuclein including evasion of Parkinson’s disease-associated deglycase DJ-1 by aggregates triggered with brain amplified fibrils. Knockout of DJ-1 and related glyoxalase-1 in cell lines increased -synuclein aggregation. Similarly, methylglyoxal treatment or CRISPR/Cas9 knockout of DJ-1 in iPSC-derived dopaminergic neurons enhanced fibril-induced aggregation and cell death. Thus, toxicity of -synuclein strains depends on aggregate burden, which is determined by monomer levels and conformation which dictates differential interactomes. Our results define parameters for iPSC-based modellingof -synuclein pathology using brain amplified fibrils and demonstrate how Parkinson’s disease-associated genes influence the phenotypic manifestation of strains in human neurons.
Project description:Dopaminergic neurons participate in fundamental physiological processes and are the cell type primarily affected in Parkinson’s disease (PD). Their analysis is challenging due to the intricate nature of their function, their involvement in diverse neurological processes, their heterogeneity and localization in deep brain regions. Consequently, most of the research on the protein dynamics of dopaminergic neurons has been performed in animal cells ex vivo. Here we use iPSC-derived, human mid-brain specific dopaminergic neurons to study general features of their proteome biology. We use differential dynamic SILAC labeling in combination with microfluidic devices to analyze local protein synthesis and transport between axons and soma. We report 105 potentially novel axonal markers and detect translocation of 269 proteins between axons and the soma in the time frame of our analysis (120 hours). Importantly, we provide evidence for local synthesis of 154 proteins in the axon and their retrograde transport to the soma. Our study provides a workflow and resource for future applications of quantitative proteomics in iPSC-derived human neurons
Project description:Induced pluripotent stem cells (iPSCs) hold great promise for in vitro disease modeling and cell replacement therapy for Parkinson’s disease (PD). Both applications crucially require an in-depth profiling of the disease-relevant, iPSC-derived cell type. Midbrain dopaminergic (mDA) neurons derived from pluripotent stem cells are of substantial interest because of their instrumental value for PD therapy. IPSC-derived mDA neuron-like cells have been generated, however, detailed genetic and epigenetic characterization of strictly purified in vitro generated DA neurons has so far lagged behind. We generated mouse Pitx3gfp/+ iPSC-derived DA neurons that, after fluorescent activated cell sorting (FACS) allowed comprehensive comparison to mesodiencephalic dopaminergic (mdDA) neurons from Fac-sorted Pitx3gfp/+ ventral midbrains. We performed detailed analysis of global gene expression and genome-scale DNA methylation of CpG islands (CGIs) by reduced representation bisulfite sequencing. The reprogramming pathway from fibroblasts to iPSCs left parental cell footprints for both gene expression and DNA methylation. However, most gene expression patterns of iPSC-derived DA neurons closely resembled that of primary mdDA neurons with the strongest correlations for mdDA specific genes. Also, for DNA methylation patterns, high similarities were found for the vast majority of CGIs when comparing primary mdDA neurons with iPSC-derived DA neurons. Additionally, we found de novo DNA methylation during in vitro differentiation for hundreds of genes specifically in lineage-committed neural precursors that persisted in iPSC-derived DA neurons. Our study provides novel detailed characteristics of iPSC-derived DA neurons in comparison to the primary cell type. These findings add important information to our knowledge about these biomedically highly valuable, in vitro generated neurons. Microarray expression study comparing 3 samples of facs-sorted, Pitx3-gfp positive cells from each experimental group to a common reference consisting of adult mouse midbrain RNA. Each sample was analysed in normal and opposite dye orientation.
Project description:Induced pluripotent stem cell (iPSC)-derived dopamine neurons provide an opportunity to model Parkinson’s disease (PD) but neuronal cultures are confounded by cellular heterogeneity. By applying high-resolution single cell transcriptomic analyses to Parkinson’s iPSC-derived dopamine neurons carrying the GBA-N370S risk variant, we exploited intra-culture cellular heterogeneity to identify a progressive axis of gene expression variation leading to endoplasmic reticulum stress. 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 compounds known to modulate HDAC4 activity upregulated genes early in the DE axis, and corrected Parkinson’s-related cellular phenotypes. Our study demonstrates how single cell transcriptomics can exploit cellular heterogeneity to reveal disease mechanisms and identify therapeutic targets.
Project description:The degenerative process in Parkinson’s disease (PD) causes a progressive loss of dopaminergic neurons (DaNs) in the nigrostriatal system. Resolving the differences in neuronal susceptibility warrants an amenable PD model that, in comparison to post-mortem human specimens, controls for environmental and genetic differences in PD pathogenesis. At present study, we generated a primate model of PD by carotid artery injection of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine MPTP and sampled substantia nigra and putamen of macaque for single cell sequencing analysis.
Project description:Induced pluripotent stem cells (iPSCs) harbor great promise for in vitro generation of disease-relevant cell types, such as mesodiencephalic dopaminergic (mdDA) neurons involved in Parkinson’s disease. Although iPSC-derived midbrain DA neurons have been generated, detailed genetic and epigenetic characterization of such neurons is still lacking. The goal of this study is to examine the authenticity of iPSC-derived DA neurons obtained by established protocols. We FACS-purified mdDA (Pitx3gfp/+) neurons derived from mouse iPSCs and primary mdDA (Pitx3gfp/+) neurons to analyze and compare their genetic and epigenetic features. Although iPSC-derived DA neurons largely adopt characteristics of their in-vivo counterparts, relevant deviations in global gene expression and DNA methylation were found. Hypermethylated genes, mainly involved in neurodevelopment and basic neuronal functions, consequently showed reduced expression levels. Such abnormalities should be addressed as they might affect unambiguous long-term functionality and hamper the potential of iPSC-derived DA neurons for in-vitro disease modeling or cell-based therapy.