Project description:Direct conversion from fibroblast to neuron has recently been successfully induced bypassing the pluripotent state. However, the conversion takes a few months with low percentages of success. Here we found that depletion of p53, which can converted fibroblasts into three major neural lineages: neurons, astrocytes and oligodendrocytes. Furthermore, our method provided a high efficiency of conversion in aging fibroblasts, where published methods failed. This finding may help developing a prototype for neuron replacement therapy, including foraging people vulnerable to neurological disorders. p53 has been shown to inhibit reprogramming of fibroblasts to iPS cells, by depletion of p53 in human fibroblasts, we study the function of p53 in induced neuron process. By induction of p53 knockdown fibroblasts with special neuron medium, we can get mature neurons directly. In the induction process, many neurogenic transcription factors were up-regulated, and we prove that p21 is not involved in this process.
Project description:Direct conversion from fibroblasts to neurons is a potential cell replacement therapy for neurological disorders, and a variety of combinations of transcription factors have been tried. We notice that the efficiency of conversion from aging fibroblasts was much lower than in early stage cells, which is consistent with the notion that cellular senescence impairs conversion of fibroblasts to neurons. Here, we found that the transient knockdown of the p16Ink4a/p19Arf locus was sufficient to convert human fibroblasts to neurons. Futhermore, expression of hTERT alone, another mechanism behind immortalization, also induced neuron conversion. Our results show that the acquisition of immortality is a crucial step for the conversion of human fibroblasts into induced neurons. Transient knockdown of p16/p19 or p53 expression or exogenous overexpression of hTERT can induce primary fibroblasts to immortality. In the following, treated cells were cultured in neuron-induction medium. We can observe the morphology change and detect the neuronal markers. Also, some of the induced neurons could generate action potentials and neurotransmitter-induced currents in optimal conditions.
Project description:We have generated isogenic induced pluripotent stem cell lines by reprogramming human fibroblasts from patients carrying the LRRK2 G2019S mutation with subsequent zinc finger nuclease - mediated targeted correction of the diseased allele. These iPS cell lines were differentiated for 30 days using a direct differentiation protocol towards midbrain dopaminergic neurons (mDANs). Isogenic human iPS cells carrying the LRRK2 WT and G2019S locus were differentiated to dopaminergic neurons to detect gene expression changes associated with mutated LRRK2.
Project description:Direct conversion from fibroblasts to neurons is a potential cell replacement therapy for neurological disorders, and a variety of combinations of transcription factors have been tried. We notice that the efficiency of conversion from aging fibroblasts was much lower than in early stage cells, which is consistent with the notion that cellular senescence impairs conversion of fibroblasts to neurons. Here, we found that the transient knockdown of the p16Ink4a/p19Arf locus was sufficient to convert human fibroblasts to neurons. Futhermore, expression of hTERT alone, another mechanism behind immortalization, also induced neuron conversion. Our results show that the acquisition of immortality is a crucial step for the conversion of human fibroblasts into induced neurons.
Project description:Lineage-specific transcription factors, which drive cellular identity during embryogenesis, have been shown to convert cell fate when express ectopically in heterologous cells. Herein, we screened the key molecular factors governing the dopaminergic neuronal specification during brain development for their ability to generate similar neurons directly from mouse and human fibroblasts. Remarkably, we found a minimal set of three factors Mash1, Nurr1 and Lmx1a/b able to elicit such cellular reprogramming. Molecular and transcriptome studies showed reprogrammed DA neurons to faithfully recapitulate gene expression of their brain homolog cells while lacking expression of other catecholaminergic neuronal types. Induced neurons showed spontaneous electrical activity organized in regular spikes consistent with the pacemaker activity featured by brain DA neurons. The three factors were able to elicit DA neuronal conversion in human fibroblasts from prenatal or adult fibroblasts of healthy donors and a Parkinson’s disease patient. Generation of DA induced neurons from somatic cells might have significant implications in studies of neural development, disease in vitro modeling and cell replacement therapies. We infected mouse embryonic fibroblasts (MEFs) isolated from TH-GFP knock-in mice embryos at E14.5, with lentiviruses expressing the three dopaminergic transcription factors Ascl1, Lmx1a and Nurr1. TH-GFP MEFs infected (Ind) by a pool of the three previously mentioned dopaminergic lentiviruses were shifted in a neuronal medium for 12 days and sorted for GFP-positive cells. Thus we extracted mRNA from Ind-GFP-positive cells and compared them to not infetced (NI) cells by means of RNA-microarray analysis.
Project description:The direct conversion of human skin fibroblasts to neurons has a low efficiency and unclear mechanism. Here, we show that the knockdown of PTBP2 (nPTB) significantly enhanced the transdifferentiation induced by ASCL1, MiR124-9/9* and p53 shRNA to generate mostly GABAergic neurons. Longitudinal RNAseq analyses identified the continuous induction of many RNA Splicing Regulators (RSRs). Among these, the knockdown of RBFOX3, which encodes the mature neuronal marker NeuN, significantly abrogated the transdifferentiation. Overexpression of RBFOX3 significantly enhanced the conversion induced by AMp; the enhancement was occluded by PTBP2 knockdown. We found that PTBP2 attenuation significantly favored neuron-specific alternative splicing (AS) of many genes involved in synaptic transmission, signal transduction, and axon formation. RBFOX3 knockdown significantly reversed the effect, while RBFOX3 overexpression enhanced it. The study reveals the critical role of neuron-specific AS in the direct conversion of human skin fibroblasts to neurons by showing that PTBP2 attenuation enhances this mechanism in concert with RBFOX3.
Project description:Direct conversion from fibroblast to neuron has recently been successfully induced bypassing the pluripotent state. However, the conversion takes a few months with low percentages of success. Here we found that depletion of p53, which can converted fibroblasts into three major neural lineages: neurons, astrocytes and oligodendrocytes. Furthermore, our method provided a high efficiency of conversion in aging fibroblasts, where published methods failed. This finding may help developing a prototype for neuron replacement therapy, including foraging people vulnerable to neurological disorders.
Project description:We have generated isogenic induced pluripotent stem cell lines by reprogramming human fibroblasts from patients carrying the LRRK2 G2019S mutation with subsequent zinc finger nuclease - mediated targeted correction of the diseased allele. These iPS cell lines were differentiated for 30 days using a direct differentiation protocol towards midbrain dopaminergic neurons (mDANs).
Project description:Direct neuronal conversion describes the process of generating induced neurons from somatic cells such as fibroblasts by overexpressing cell type-specific transcription factors. This was first achieved by expressing Brn2, Ascl1 and MytL1 in mouse fibroblasts, and was later achieved in human cells by inclusion of additional factors such as NeuroD1. Here, we present the first protocol for directly converting porcine fibroblasts into induced neurons. We used lentivirus-mediated delivery of previously identified neuronal-specifying transcription factors and microRNAs and evaluated morphology and neuronal marker expression after ten days of conversion. We found that Ascl1 and microRNAs, miR-9/9* and miR-124 together generated more neuronal cells than other conditions tested. The porcine induced neurons expressed common mature markers such as MAP2 and Synaptophysin after four weeks of conversion. Transcriptomic analysis revealed that fibroblast-specific signatures were silenced early in the conversion process, while the neuronal programs increased and matured during conversion. We generated a heterogenous population of glutamatergic and GABAergic neurons.