Project description:CRISPR/Cas9-based functional genomics have transformed our ability to elucidate mammalian cell biology. Most previous CRISPR-based screens were implemented in cancer cell lines, rather than healthy, differentiated cells. Here, we describe a CRISPR interference (CRISPRi)-based platform for genetic screens in human neurons derived from induced pluripotent stem cells (iPSCs). We demonstrate robust and durable knockdown of endogenous genes in such neurons, and present results from three complementary genetic screens. A survival-based screen revealed neuron-specific essential genes and a small number of genes that improved neuronal survival upon knockdown. A screen with a single-cell transcriptomic readout uncovered several examples for genes knockdown of which had dramatically different cell-type specific consequences. A longitudinal imaging screen detected distinct consequences of gene knockdown on neuronal morphology. Our results highlight the potential of interrogating cell biology in iPSC-derived differentiated cell types and provide a platform for the systematic dissection of normal and disease states of neurons.
Project description:CRISPR/Cas9-based functional genomics have transformed our ability to elucidate mammalian cell biology. However, most previous CRISPR-based screens were conducted in cancer cell lines rather than healthy, differentiated cells. Here, we describe a CRISPR interference (CRISPRi)-based platform for genetic screens in human neurons derived from induced pluripotent stem cells (iPSCs). We demonstrate robust and durable knockdown of endogenous genes in such neurons and present results from three complementary genetic screens. First, a survival-based screen revealed neuron-specific essential genes and genes that improved neuronal survival upon knockdown. Second, a screen with a single-cell transcriptomic readout uncovered several examples of genes whose knockdown had strikingly cell-type-specific consequences. Third, a longitudinal imaging screen detected distinct consequences of gene knockdown on neuronal morphology. Our results highlight the power of unbiased genetic screens in iPSC-derived differentiated cell types and provide a platform for systematic interrogation of normal and disease states of neurons. VIDEO ABSTRACT.
Project description:Neurons are unique among all human cell types in their high energy demand, long lifespans and rich lipid contents. As such, neurons exhibit unique vulnerability to oxidative stress caused by redox imbalance in aging and neurodegenerative diseases (NDDs). To systematically identify regulators of neuronal survival under oxidative stress and regulators of neuronal redox homeostasis, we conducted multiple survival- and FACS-based genome-wide screens in human iPSC-derived neurons, using our functional genomics toolkit including a previously established CRISPRi approach and a newly developed CRISPRa approach. So far, these are the first genome-wide screens in human neurons. Our results revealed that inhibiting glycosphingolipids (GSLs) degradation by depletion of prosaposin (PSAP) drives the formation of lipofuscins in neurons which leads to iron accumulation and strongly induces ROS production that oxidizing lipids and leads to neuronal ferroptosis under oxidative stress. We also conducted single cell CROP-seq screens that revealed transcriptomic signatures of NDD-associated genes. These datasets are freely available through our open-access database CRISPRbrain.
Project description:All bulk CRISPR based screens CD2 and B2M CRISPRi tiling screens (primary human CD8 T cells), IL2RA CRISPRa tiling screens (Jurkats), CRISPRi/a TF screens (primary human CD8 T cells), and CRISPR TFome KO (primary human T cells)
Project description:Hexanucleotide repeat expansions in the C9orf72 gene are the most common cause of amyotrophic lateral sclerosis and frontotemporal dementia (c9FTD/ALS). The nucleotide repeat expansions are translated into dipeptide repeat (DPR) proteins, which are aggregation-prone and may contribute to neurodegeneration. We used the CRISPR-Cas9 system to perform genome-wide gene knockout screens for suppressors and enhancers of C9orf72 DPR toxicity in human cells. We validated hits by performing secondary CRISPR-Cas9 screens in primary mouse neurons. We uncovered potent modifiers of DPR toxicity whose gene products function in nucleocytoplasmic transport, the endoplasmic reticulum (ER), proteasome, RNA processing pathways, and in chromatin modification. One modifier, TMX2, modulated the ER-stress signature elicited by C9orf72 DPRs in neurons, and improved survival of human induced motor neurons from C9orf72 ALS patients. Together, this work demonstrates the promise of CRISPR-Cas9 screens to define mechanisms of neurodegenerative diseases. This dataset contains the RNA-sequencing data used to support the conclusions from this study.
Project description:Proteostasis involves a dynamic network of biological pathways that regulate protein synthesis, maintenance, and degradation. As postmitotic cells, neurons are particularly sensitive to environmental changes, and dysfunction in cellular proteostasis can lead to an accumulation of aggregated and misfolded proteins. However, how proteins turnover on a global scale in human neurons is not well understood. In this study, we systematically improved a dynamic SILAC proteomic approach to enable a deep and accurate measurement of protein turnover in human induced pluripotent stem cell (iPSC)-derived cholinergic spinal motor and glutamatergic cortical neurons. Furthermore, we applied this deep proteome turnover method to evaluate how inhibiting the ubiquitin-proteasome and lysosome-autophagy pathway impacts proteostasis in iPSC-derived neurons. Using these datasets, we developed a freely available resource called Neuron Profile, an interactive website for visualizing and querying protein turnover in subcellular locations in human neurons.