Project description:Non-familial Alzheimer’s disease (AD) occurring before 65 years of age is commonly referred to as early-onset Alzheimer’s disease (EOAD) and constitutes ~5-6% of all Alzheimer’s disease (AD) cases. While EOAD exhibits the same clinicopathological changes such as amyloid plaques, neurofibrillary tangles (NFTs), brain atrophy, and cognitive decline as observed in the more prevalent late-onset AD (LOAD), EOAD patients tend to have more severe cognitive deficits, including visuospatial, language, and motor dysfunction. Patient-derived induced pluripotent stem cells (iPSCs) have been used to model and study penetrative, familial AD (FAD) mutations in APP, PSEN1, and PSEN2, but have been seldom used for sporadic forms of AD that display more heterogeneous disease manifestation. In this study, we sought to characterize iPSC-derived neurons from EOAD patients via RNA-sequencing. A modest difference in expression profiles between EOAD patients and non-demented control subjects resulted in a limited number of differentially expressed genes (DEGs). Based on this analysis, we provide evidence that iPSC-derived neuron model systems, likely due to the loss of EOAD-associated epigenetic signatures during the iPSC reprogramming, are not an ideal model system to study sporadic AD.
Project description:Reprogramming somatic cells to induced pluripotent stem cells (iPSCs) sets their identity back to an embryonic age. This presents a fundamental hurdle for modeling late-onset disorders using iPSC-derived cells. We therefore developed a strategy to induce age-like features in multiple iPSC-derived lineages and tested its impact on modeling Parkinson’s disease (PD). We first describe markers that predict fibroblast donor age and observed the loss of these age-related markers following iPSC induction and re-differentiation into fibroblasts. Remarkably, age-related markers were readily induced in iPSC-derived fibroblasts or neurons following exposure to progerin including dopamine neuron-specific phenotypes such as neuromelanin accumulation. Induced aging in PD-iPSC-derived dopamine neurons revealed disease phenotypes requiring both aging and genetic susceptibility such as frank dendrite degeneration, progressive loss of tyrosine-hydroxylase expression and enlarged mitochondria or Lewy body-precursor inclusions. Our study presents a strategy for inducing age-related cellular properties and enables the modeling of late-onset disease features. Induced pluripotent stem cell-derived midbrain dopamine neurons from a young and old donor overexpressing either GFP or Progerin.
Project description:Alzheimer’s disease (AD) is the most common neurodegenerative dementia. Around 10% of cases present an age of onset before 65 years-old, which in turn can be divided in monogenic or familial AD (FAD) and sporadic early-onset AD (EOAD). Mutations in PSEN1, PSEN2 and APP genes have been linked with FAD. The aim of our study was to describe the brain whole-genome RNA expression profile of the posterior cingulate area in EOAD and FAD caused by PSEN1 mutations (FAD-PSEN1). 14 patients (7 EOAD and 7 FAD-PSEN1) and 7 neurologically healthy controls were selected and samples were hybridized in a Human Gene 1.1 microarray from Affymetrix. When comparing controls with EOAD and controls with FAD-PSEN1, we found 3183 and 3351 differentially expressed genes (DEG) respectively (FDR corrected p<0.05). However, any DEG was found in the comparison of the two groups of patients. Microarrays were validated through quantitative-PCR of 17 DEG. In silico analysis of the DEG revealed an alteration in biological pathways related to calcium-signaling, axon guidance and long-term potentiation (LTP), among others, in both groups of patients. These pathways are mainly related with cell signalling cascades, synaptic plasticity and learning and memory processes. In conclusion, the altered biological final pathways in EOAD and FAD-PSEN1 are highly coincident. Also, the findings are in line with those previously reported for late-onset AD (LOAD, onset >65 years-old), which implies that the consequences of the disease at the molecular level are similar in the final stages of the disease. 21 Samples were analyzed: 7 controls, 7 Early-onset Alzheimer's disease (AD) patients and 7 early-onset AD genetically determined by a mutation in PSEN1 gene.
Project description:Reprogramming somatic cells to induced pluripotent stem cells (iPSCs) sets their identity back to an embryonic age. This presents a fundamental hurdle for modeling late-onset disorders using iPSC-derived cells. We therefore developed a strategy to induce age-like features in multiple iPSC-derived lineages and tested its impact on modeling Parkinson’s disease (PD). We first describe markers that predict fibroblast donor age and observed the loss of these age-related markers following iPSC induction and re-differentiation into fibroblasts. Remarkably, age-related markers were readily induced in iPSC-derived fibroblasts or neurons following exposure to progerin including dopamine neuron-specific phenotypes such as neuromelanin accumulation. Induced aging in PD-iPSC-derived dopamine neurons revealed disease phenotypes requiring both aging and genetic susceptibility such as frank dendrite degeneration, progressive loss of tyrosine-hydroxylase expression and enlarged mitochondria or Lewy body-precursor inclusions. Our study presents a strategy for inducing age-related cellular properties and enables the modeling of late-onset disease features.
Project description:Late-onset Alzheimer’s disease (LOAD) is the most common form of AD. However, modeling sporadic LOAD, without clear genetic predispositions, to capture hallmark neuronal pathologies such as extracellular amyloid-β (Aβ) plaque deposition, intracellular tau tangles, and neuronal loss, remains an unmet need. Here, we demonstrate that neurons generated by microRNA-based direct reprogramming of fibroblasts from patients affected by autosomal dominant AD (ADAD) and LOAD in a three-dimensional (3D) environment, effectively recapitulate key neuropathological features of AD without additional cellular or genetic insults. These LOAD neurons exhibit Aβ-dependent neurodegeneration, as treatment with β- or γ-secretase inhibitors before (but not subsequent to) Aβ deposit formation mitigated neuronal death. Moreover, inhibiting age-associated retrotransposable elements (RTEs) in LOAD neurons reduced both Ab deposition and neurodegeneration. Our study underscores the efficacy of modeling late-onset neuropathology of LOAD through high-efficiency microRNA-based neuronal reprogramming.
Project description:Late-onset Alzheimer’s disease (LOAD) is the most common form of AD. However, modeling sporadic LOAD, without clear genetic predispositions, to capture hallmark neuronal pathologies such as extracellular amyloid-β (Aβ) plaque deposition, intracellular tau tangles, and neuronal loss, remains an unmet need. Here, we demonstrate that neurons generated by microRNA-based direct reprogramming of fibroblasts from patients affected by autosomal dominant AD (ADAD) and LOAD in a three-dimensional (3D) environment, effectively recapitulate key neuropathological features of AD without additional cellular or genetic insults. These LOAD neurons exhibit Aβ-dependent neurodegeneration, as treatment with β- or γ-secretase inhibitors before (but not subsequent to) Aβ deposit formation mitigated neuronal death. Moreover, inhibiting age-associated retrotransposable elements (RTEs) in LOAD neurons reduced both Ab deposition and neurodegeneration. Our study underscores the efficacy of modeling late-onset neuropathology of LOAD through high-efficiency microRNA-based neuronal reprogramming.
Project description:Late-onset Alzheimer’s disease (LOAD) is the most common form of AD. However, modeling sporadic LOAD, without clear genetic predispositions, to capture hallmark neuronal pathologies such as extracellular amyloid-β (Aβ) plaque deposition, intracellular tau tangles, and neuronal loss, remains an unmet need. Here, we demonstrate that neurons generated by microRNA-based direct reprogramming of fibroblasts from patients affected by autosomal dominant AD (ADAD) and LOAD in a three-dimensional (3D) environment, effectively recapitulate key neuropathological features of AD without additional cellular or genetic insults. These LOAD neurons exhibit Aβ-dependent neurodegeneration, as treatment with β- or γ-secretase inhibitors before (but not subsequent to) Aβ deposit formation mitigated neuronal death. Moreover, inhibiting age-associated retrotransposable elements (RTEs) in LOAD neurons reduced both Ab deposition and neurodegeneration. Our study underscores the efficacy of modeling late-onset neuropathology of LOAD through high-efficiency microRNA-based neuronal reprogramming.
Project description:Alzheimer’s disease (AD) is the most common neurodegenerative dementia. Around 10% of cases present an age of onset before 65 years-old, which in turn can be divided in monogenic or familial AD (FAD) and sporadic early-onset AD (EOAD). Mutations in PSEN1, PSEN2 and APP genes have been linked with FAD. The aim of our study was to describe the brain whole-genome RNA expression profile of the posterior cingulate area in EOAD and FAD caused by PSEN1 mutations (FAD-PSEN1). 14 patients (7 EOAD and 7 FAD-PSEN1) and 7 neurologically healthy controls were selected and samples were hybridized in a Human Gene 1.1 microarray from Affymetrix. When comparing controls with EOAD and controls with FAD-PSEN1, we found 3183 and 3351 differentially expressed genes (DEG) respectively (FDR corrected p<0.05). However, any DEG was found in the comparison of the two groups of patients. Microarrays were validated through quantitative-PCR of 17 DEG. In silico analysis of the DEG revealed an alteration in biological pathways related to calcium-signaling, axon guidance and long-term potentiation (LTP), among others, in both groups of patients. These pathways are mainly related with cell signalling cascades, synaptic plasticity and learning and memory processes. In conclusion, the altered biological final pathways in EOAD and FAD-PSEN1 are highly coincident. Also, the findings are in line with those previously reported for late-onset AD (LOAD, onset >65 years-old), which implies that the consequences of the disease at the molecular level are similar in the final stages of the disease.
Project description:Our understanding of Alzheimer’s disease (AD) pathogenesis is currently limited by difficulties in obtaining live neurons from patients and the inability to model the sporadic form of AD. It may be possible to overcome these challenges by reprogramming primary cells from patients into induced pluripotent stem cells (iPSCs). We reprogrammed primary fibroblasts from two patients with familial AD (both caused by a duplication of APP1, APPDp), two with sporadic AD (sAD1, 2) and two non-demented control individuals (NDCs) into iPSC lines. Neurons from differentiated cultures were FACS-purified and characterized. Purified cultures contained >90% neurons, clustered with fetal brain mRNA samples by microarray criteria, and could form functional synaptic contacts. Virtually all cells exhibited normal electrophysiological activity. Relative to controls, iPSC-derived, purified neurons from the two APPDp patients and patient sAD2 exhibited significantly higher levels of secreted Aβ1-40, phospho-tauThr231 (pTau) and active GSK3β (aGSK3β). Neurons from APPDp and sAD2 patients also accumulated large Rab5-positive early endosomes compared to controls. Treatment of purified neurons with β-secretase inhibitors, but not g-secretase inhibitors, caused significant reductions in pTau and aGSK3β levels. These results suggest a direct relationship between APP proteolytic processing, but not Aβ, in GSK3β activation and tau phosphorylation in human neurons. Additionally, we observed that neurons with the genome of one sAD patient exhibited the phenotypes seen in familial AD samples. More generally, we demonstrate that iPSC technology can be used to observe phenotypes relevant to AD, even though it can take decades for overt disease to manifest in patients. Total RNA extracted from normal hIPSCs, Alzheimer's patient derived hIPSCs, neurons differentiated from hIPSCs, fetal brain, fetal heart, fetal liver and fetal lung