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: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:Hutchinson-Gilford progeria syndrome (HGPS) is a rare and fatal human premature aging disease1-5, characterized by premature atherosclerosis and degeneration of vascular smooth muscle cells (SMCs)6-8. HGPS is caused by a single-point mutation in the LMNA gene, resulting in the generation of progerin, a truncated mutant of lamin A. Accumulation of progerin leads to various aging-associated nuclear defects including disorganization of nuclear lamina and loss of heterochromatin9-12. Here, we report the generation of induced pluripotent stem cells (iPSCs) from fibroblasts obtained from patients with HGPS. HGPS-iPSCs show absence of progerin, and more importantly, lack the nuclear envelope and epigenetic alterations normally associated with premature aging. Upon differentiation of HGPS-iPSCs, progerin and its associated aging consequences are restored. In particular, directed differentiation of HGPS-iPSCs to SMCs leads to the appearance of premature senescent SMC phenotypes associated with vascular aging. Additionally, our studies identify DNA-dependent protein kinase catalytic subunit (DNAPKcs) as a component of the progerin-containing protein complex. The absence of nuclear DNAPKcs correlates with premature as well as physiological aging. Since progerin also accumulates during physiological aging6,12,13, our results provide an in vitro iPSC-based model with an acceleration progerin accumulation to study the pathogenesis of human premature and physiological vascular aging. Microarray gene expression profiling was done to: (1) Compare differences between WT fibroblasts and fibroblasts from patients suffering of the Hutchinson-Gilford progeria syndrome (2) Check that iPSC originating from WT and patients are in fact similar to ESC
Project description:Hutchinson-Gilford progeria syndrome (HGPS) is a rare and fatal human premature aging disease1-5, characterized by premature atherosclerosis and degeneration of vascular smooth muscle cells (SMCs)6-8. HGPS is caused by a single-point mutation in the LMNA gene, resulting in the generation of progerin, a truncated mutant of lamin A. Accumulation of progerin leads to various aging-associated nuclear defects including disorganization of nuclear lamina and loss of heterochromatin9-12. Here, we report the generation of induced pluripotent stem cells (iPSCs) from fibroblasts obtained from patients with HGPS. HGPS-iPSCs show absence of progerin, and more importantly, lack the nuclear envelope and epigenetic alterations normally associated with premature aging. Upon differentiation of HGPS-iPSCs, progerin and its associated aging consequences are restored. In particular, directed differentiation of HGPS-iPSCs to SMCs leads to the appearance of premature senescent SMC phenotypes associated with vascular aging. Additionally, our studies identify DNA-dependent protein kinase catalytic subunit (DNAPKcs) as a component of the progerin-containing protein complex. The absence of nuclear DNAPKcs correlates with premature as well as physiological aging. Since progerin also accumulates during physiological aging6,12,13, our results provide an in vitro iPSC-based model with an acceleration progerin accumulation to study the pathogenesis of human premature and physiological vascular aging.
Project description:Aging and its physiological manifestations have been correlated with adult stem cell exhaustion and a failure to maintain tissue homeostasis1-10. Since multiple morphological cellular defects are associated with aging-related disorders, we hypothesized that late onset disorders might be linked to adult stem cell abnormalities compromising cellular function over time. Our work shows that a dominant G2019S mutation in the human LRRK2 gene, which is associated with central nervous system disorders, including Parkinson’s disease, the second most prevalent neurodegenerative disease in the aging population, causes alterations in neural stem cell homeostasis in aging-related cellular contexts. They include disruption of the nuclear architecture, deficiencies in clonal expansion and alterations in neural differentiation assays as well as an increased susceptibility to proteasomal stress. These phenotypic changes are dependent on differential kinase activity manifested during cellular passaging. Our studies might open new venues for studying the influence of aging in neural stem cell dependent processes, such as cognitive impairments, in the degenerating diseased brain. Genome-wide localization of Histon K4 trimethylation in human iPSC and iPSC-derived neural stem cell using ChIP-seq
Project description:Parkinson’s disease, one of the most common aging-associated neurodegenerative disorders, is characterised by nigrostriatal pathway dysfunction, caused by the gradual loss of dopaminergic neurons in the substantia nigra pars compacta of the midbrain and the dopamine depletion in the striatum. State of the art, human in vitro models are enabling the study of the dopaminergic neurons’ loss, but not the dysregulation of the dopaminergic network in the nigrostriatal pathway. Additionally, these models do not incorporate aging characteristics necessary for the development of PD. Therefore, it is conceivable that research conducted using these models overlooked numerous processes that contribute to disease’s phenotypes. Here we present a method for the generation of a midbrain-striatum assembloid model with inducible aging. Aging is induced by expression of progerin. We show that these assembloids are capable of developing characteristics of the nigrostriatal connectivity, with dopamine release from the midbrain to striatum and synapses formation between midbrain and striatal neurons. Moreover, progerin-overexpressing assembloids acquire aging phenotypes that lead to early phenotypes of Parkinson’s disease. This new model shall help to reveal the contribution of aging as well as nigrostriatal connectivity to the onset and progression of PD.
Project description:In late-onset sporadic Alzheimer’s disease (AD), the most prevalent and strongest risk factor is the ε4 allele of the apolipoprotein E (APOE4). To investigate the pathophysiological effects of the APOE4 genotype in the human cellular context, we generated isogenic iPSC-derived astrocytes bearing APOE4 alleles from APOE3 control iPSC. Next, to identify astrocytic APOE4-specific secreted proteomes, we performed a mass spectrometry using culture media from human astrocytes carrying APOE3 or APOE4.
Project description:Hutchinson-Gilford Progeria Syndrome (HGPS) is caused by a point mutation in the LMNA gene that activates a cryptic donor splice site and yields a truncated form of prelamin A called progerin. Small amounts of progerin are also produced during normal aging. Studies with mouse models of HGPS have allowed the recent development of the first therapeutic approaches for this disease. However, none of these earlier works have addressed the aberrant and pathogenic LMNA splicing observed in HGPS patients because of the lack of an appropriate mouse model. We report herein a genetically modified mouse strain that carries the HGPS mutation. These mice accumulate progerin, present histological and transcriptional alterations characteristic of progeroid models, and phenocopy the main clinical manifestations of human HGPS, including shortened life span and bone and cardiovascular aberrations. By using this animal model, we have developed an antisense morpholino–based therapy that prevents the pathogenic Lmna splicing, dramatically reducing the accumulation of progerin and its associated nuclear defects. Treatment of mutant mice with these morpholinos led to a marked amelioration of their progeroid phenotype and substantially extended their life span, supporting the effectiveness of antisense oligonucleotide–based therapies for treating human diseases of accelerated aging. 6 samples, three from LmnaG609G/G609G mice and three from control Lmna+/+ mice
Project description:Hutchinson-Gilford progeria syndrome (HGPS) is a premature aging disease caused by progerin accumulation. However, the mechanism of how progerin causes cell defects is unclear in HGPS cells. To further investigate the possible mechanism, we used Flag-tagged progerin as bait in mass spectrometry to survey the possible regulatory factors.
Project description:Hutchinson Gilford Progeria Syndrome (HGPS) is a rare, sporadic genetic disease caused by mutations in the nuclear lamin A gene. In most cases the mutation creates an efficient donor-splice site that generates an altered transcript encoding a truncated lamin A protein, progerin. In vitro studies have indicated that progerin can disrupt nuclear function. HGPS affects mainly mesenchymal lineages but the shortage of patient material has precluded a tissue-wide molecular survey of progerin’s cellular impact. We report here a new, induced pluripotent stem cell (iPSC)-based model for studying HGPS. HGPS dermal fibroblasts were reprogrammed into iPSC lines using a cocktail of the transcription factor genes, OCT4, SOX2, KLF4 and C-MYC. The iPSC cells were differentiated into neural progenitors (NPs), endothelial cells (ECs), fibroblast-like cells and mesenchymal stem cells (MSCs). Progerin levels in the different cell types followed the pattern MSC≥ fibroblast>EC>>NP. Functionally, we detected a major impact of progerin on MSC function. We show that HGPS-MSCs are vulnerable to the ischemic conditions found in a murine hind limb recovery model and an in vitro hypoxia assay, as well as showing enhanced sensitivity in a serum starvation assay. Since there is widespread consensus that MSCs reside in low oxygen niches in vivo, we propose that these conditions lead to an accelerated depletion of the MSC pool in HGPS patients with consequent accretion of mesenchymal tissue.