Project description:Human neurons engineered from induced pluripotent stem cells (iPSCs) through Neurogenin 2 (Ngn2) overexpression are widely used to study neuronal differentiation mechanisms and to model neurological diseases. However, the differentiation paths and heterogeneity of emerged neurons have not been fully explored. Here we used single-cell transcriptomics to dissect the cell states that emerge during Ngn2 overexpression across a time course from pluripotency to neuron functional maturation. We find a substantial molecular heterogeneity in the neuron types generated, with at least two populations that express genes associated with neurons of the peripheral nervous system. Neuron heterogeneity is observed across multiple iPSC clones and lines from different individuals. We find that neuron fate acquisition is sensitive to Ngn2 expression level and the duration of Ngn2 forced expression. Our data reveals that Ngn2 dosage can regulate neuron fate acquisition, and that Ngn2-iN heterogeneity can confound results that are sensitive to neuron type.
Project description:This bulk RNAseq dataset is part of a dataset described in the manuscript titled "Fully defined NGN2 neuron protocol reveals diverse signatures of neuronal maturation". This dataset includes NPC derived neurons using a wild type iPSC line, and was used to validate a MS-117 maturation score which attempt to establish a socre system to assess neuronal maturation with iPSCs derived neurons.
Project description:Two closely related proneural bHLH transcription factors, Ascl1 and Ngn2, both can induce mouse embryonic stem cells to differentiate into induced neurons. Although Ascl1 and Ngn2 induced transcriptional programs partially overlap, it is not known whether the differences translate into the distinct mechanisms. We found that both transcription factors induce mutually exclusive side populations by binding and inducing different lineage drivers. Furthermore, Ascl1 rapidly dismantles the pluripotency network and installs neuronal and trophoblast cell fates, while Ngn2 generates a neural stem cell-like intermediate supported by incomplete shutdown of the pluripotency network. Using CRISPR-Cas9 knockout screening, we revealed differential genetic dependencies between Ascl1 and Ngn2. Specifically, Ascl1 is more dependent on factors including Tcf7l1, that regulate pluripotency and cell cycle. In the absence of the pluripotency network repressor Tcf7l1 Ascl1 is still able to repress the core pluripotency genes, however failed to exit cell cycle. Overexpression of Cdkn1c induced cell cycle exit and restored the generation of neurons. This study illuminates two different mechanistic approaches to convert ESC to induced neurons: rapid shutdown of the initial state while installing a terminal cell identity versus repurposing the initial gene regulatory network to allow generation of neurons via intermediate states. Understanding the precise mechanism and the variety of cell states induced is essential to design efficient cell replacement therapeutic applications or precise tools for disease modelling.
Project description:Two closely related proneural bHLH transcription factors, Ascl1 and Ngn2, both can induce mouse embryonic stem cells to differentiate into induced neurons. Although Ascl1 and Ngn2 induced transcriptional programs partially overlap, it is not known whether the differences translate into the distinct mechanisms. We found that both transcription factors induce mutually exclusive side populations by binding and inducing different lineage drivers. Furthermore, Ascl1 rapidly dismantles the pluripotency network and installs neuronal and trophoblast cell fates, while Ngn2 generates a neural stem cell-like intermediate supported by incomplete shutdown of the pluripotency network. Using CRISPR-Cas9 knockout screening, we revealed differential genetic dependencies between Ascl1 and Ngn2. Specifically, Ascl1 is more dependent on factors including Tcf7l1, that regulate pluripotency and cell cycle. In the absence of the pluripotency network repressor Tcf7l1 Ascl1 is still able to repress the core pluripotency genes, however failed to exit cell cycle. Overexpression of Cdkn1c induced cell cycle exit and restored the generation of neurons. This study illuminates two different mechanistic approaches to convert ESC to induced neurons: rapid shutdown of the initial state while installing a terminal cell identity versus repurposing the initial gene regulatory network to allow generation of neurons via intermediate states. Understanding the precise mechanism and the variety of cell states induced is essential to design efficient cell replacement therapeutic applications or precise tools for disease modelling.
Project description:Two closely related proneural bHLH transcription factors, Ascl1 and Ngn2, both can induce mouse embryonic stem cells to differentiate into induced neurons. Although Ascl1 and Ngn2 induced transcriptional programs partially overlap, it is not known whether the differences translate into the distinct mechanisms. We found that both transcription factors induce mutually exclusive side populations by binding and inducing different lineage drivers. Furthermore, Ascl1 rapidly dismantles the pluripotency network and installs neuronal and trophoblast cell fates, while Ngn2 generates a neural stem cell-like intermediate supported by incomplete shutdown of the pluripotency network. Using CRISPR-Cas9 knockout screening, we revealed differential genetic dependencies between Ascl1 and Ngn2. Specifically, Ascl1 is more dependent on factors including Tcf7l1, that regulate pluripotency and cell cycle. In the absence of the pluripotency network repressor Tcf7l1 Ascl1 is still able to repress the core pluripotency genes, however failed to exit cell cycle. Overexpression of Cdkn1c induced cell cycle exit and restored the generation of neurons. This study illuminates two different mechanistic approaches to convert ESC to induced neurons: rapid shutdown of the initial state while installing a terminal cell identity versus repurposing the initial gene regulatory network to allow generation of neurons via intermediate states. Understanding the precise mechanism and the variety of cell states induced is essential to design efficient cell replacement therapeutic applications or precise tools for disease modelling.
Project description:Two closely related proneural bHLH transcription factors, Ascl1 and Ngn2, both can induce mouse embryonic stem cells to differentiate into induced neurons. Although Ascl1 and Ngn2 induced transcriptional programs partially overlap, it is not known whether the differences translate into the distinct mechanisms. We found that both transcription factors induce mutually exclusive side populations by binding and inducing different lineage drivers. Furthermore, Ascl1 rapidly dismantles the pluripotency network and installs neuronal and trophoblast cell fates, while Ngn2 generates a neural stem cell-like intermediate supported by incomplete shutdown of the pluripotency network. Using CRISPR-Cas9 knockout screening, we revealed differential genetic dependencies between Ascl1 and Ngn2. Specifically, Ascl1 is more dependent on factors including Tcf7l1, that regulate pluripotency and cell cycle. In the absence of the pluripotency network repressor Tcf7l1 Ascl1 is still able to repress the core pluripotency genes, however failed to exit cell cycle. Overexpression of Cdkn1c induced cell cycle exit and restored the generation of neurons. This study illuminates two different mechanistic approaches to convert ESC to induced neurons: rapid shutdown of the initial state while installing a terminal cell identity versus repurposing the initial gene regulatory network to allow generation of neurons via intermediate states. Understanding the precise mechanism and the variety of cell states induced is essential to design efficient cell replacement therapeutic applications or precise tools for disease modelling.
Project description:NGN2-driven iPSC-to-neuron conversion is a popular method for human neurological disease modeling. In this study, we report a fully standardized approach for generating functional excitatory cortical neurons. This method utilizes clonal, targeted-engineered iPSC lines and employs fully defined reagents. We demonstrate that our protocol generates consistent excitatory cortical neurons at scale. Comprehensive temporal omics, electrophysiological, and morphological profilings indicate the continued progression of neuronal maturation for at least 150 days. Deep quantitative characterizations through transcriptomic, imaging, and functional assays reveal coordinated actions of multiple pathways driving neuronal maturation. The neurons express the majority of the key risk genes in Alzheimer's disease, Parkinson's disease, and autism, demonstrating the relevance of our protocol in modeling human neurological disorders. This well-defined method, profiling data, and functional characterization provide a solid and reliable framework for developing human in vitro neuronal models for disease modeling.
Project description:Human neurons engineered from induced pluripotent stem cells (iPSCs) through neurogenin 2 (NGN2) overexpression are widely used to study neuronal differentiation mechanisms and to model neurological diseases. However, the differentiation paths and heterogeneity of emerged neurons have not been fully explored. Here, we used single-cell transcriptomics to dissect the cell states that emerge during NGN2 overexpression across a time course from pluripotency to neuron functional maturation. We find a substantial molecular heterogeneity in the neuron types generated, with at least two populations that express genes associated with neurons of the peripheral nervous system. Neuron heterogeneity is observed across multiple iPSC clones and lines from different individuals. We find that neuron fate acquisition is sensitive to NGN2 expression level and the duration of NGN2-forced expression. Our data reveal that NGN2 dosage can regulate neuron fate acquisition, and that NGN2-iN heterogeneity can confound results that are sensitive to neuron type.
Project description:Direct conversion of iPSCs into neurons by NGN2 over-expression is a popular method for disease modeling. Here we report a standardized method to generate functional excitatory cortical neurons using clonal, targeted engineered iPSC lines and defined reagents. We demonstrate that our protocol generates consistent excitatory cortical neurons at scale. These cultures can be maintained healthily for at least 150 days and expresses the majority of the GWAS genes found in autism, Parkinson’s disease, and Alzheimer’s disease. Comprehensive temporal omics, functional, and morphological profiling demonstrated continued progression of neuronal maturation. Deep functional characterization through transcriptomic, imaging, and functional assays revealed the coordinated action of multiple pathways in neuronal maturation. Our method and profiling data can serve as reference for developing human in vitro neuronal models for disease modeling.