Project description:The coordination of developmental potential and proliferation in stem and progenitor cells is essential for mammalian development and tissue homeostasis. To better understand this coordination in human neural progenitor cells (hNPCs), we performed CRISPR-Cas9 screens and identified genes that limit their expansion. These screens revealed that knockout of growth-limiting genes, including CREBBP, NF2, PTPN14, TAOK1, or TP53, caused increased hNPC expansion via skipping of a transient G0-like state, accompanied by transcriptional reprogramming of G1 subpopulations. Hallmarks of the G0-like state included expression of genes associated with quiescent neural stem cells and neural development and molecular features found in quiescent cells (e.g., hypo-phosphorylated Rb, CDK2low activity, and p27high). Further, G0-skip genes act through both distinct and convergent downstream effectors, including cell cycle, Hippo-YAP, and novel targets. The results suggest that hNPC expansion is constrained by a transient G0-like state, regulated by multiple pathways, that facilitates retention of neurodevelopmental identity.
Project description:The coordination of developmental potential and proliferation in stem and progenitor cells is essential for mammalian development and tissue homeostasis. To better understand this coordination in human neural progenitor cells (hNPCs), we performed CRISPR-Cas9 screens and identified genes that limit their expansion. These screens revealed that knockout of growth-limiting genes, including CREBBP, NF2, PTPN14, TAOK1, or TP53, caused increased hNPC expansion via skipping of a transient G0-like state, accompanied by transcriptional reprogramming of G1 subpopulations. Hallmarks of the G0-like state included expression of genes associated with quiescent neural stem cells and neural development and molecular features found in quiescent cells (e.g., hypo-phosphorylated Rb, CDK2low activity, and p27high). Further, G0-skip genes act through both distinct and convergent downstream effectors, including cell cycle, Hippo-YAP, and novel targets. The results suggest that hNPC expansion is constrained by a transient G0-like state, regulated by multiple pathways, that facilitates retention of neurodevelopmental identity.
Project description:The coordination of developmental potential and proliferation in stem and progenitor cells is essential for mammalian development and tissue homeostasis. To better understand this coordination in human neural progenitor cells (hNPCs), we performed CRISPR-Cas9 screens and identified genes that limit their expansion. These screens revealed that knockout of growth-limiting genes, including CREBBP, NF2, PTPN14, TAOK1, or TP53, caused increased hNPC expansion via skipping of a transient G0-like state, accompanied by transcriptional reprogramming of G1 subpopulations. Hallmarks of the G0-like state included expression of genes associated with quiescent neural stem cells and neural development and molecular features found in quiescent cells (e.g., hypo-phosphorylated Rb, CDK2low activity, and p27high). Further, G0-skip genes act through both distinct and convergent downstream effectors, including cell cycle, Hippo-YAP, and novel targets. The results suggest that hNPC expansion is constrained by a transient G0-like state, regulated by multiple pathways, that facilitates retention of neurodevelopmental identity.
Project description:Ageing impairs the ability of neural stem cells (NSCs) to transition from quiescence to proliferation in the adult mammalian brain. Functional decline of NSCs results in the decreased production of new neurons and defective regeneration following injury during ageing1-4. Several genetic interventions have been found to ameliorate old brain function5-8, but systematic functional testing of genes in old NSCs-and more generally in old cells-has not been done. Here we develop in vitro and in vivo high-throughput CRISPR-Cas9 screening platforms to systematically uncover gene knockouts that boost NSC activation in old mice. Our genome-wide screens in primary cultures of young and old NSCs uncovered more than 300 gene knockouts that specifically restore the activation of old NSCs. The top gene knockouts are involved in cilium organization and glucose import. We also establish a scalable CRISPR-Cas9 screening platform in vivo, which identified 24 gene knockouts that boost NSC activation and the production of new neurons in old brains. Notably, the knockout of Slc2a4, which encodes the GLUT4 glucose transporter, is a top intervention that improves the function of old NSCs. Glucose uptake increases in NSCs during ageing, and transient glucose starvation restores the ability of old NSCs to activate. Thus, an increase in glucose uptake may contribute to the decline in NSC activation with age. Our work provides scalable platforms to systematically identify genetic interventions that boost the function of old NSCs, including in vivo, with important implications for countering regenerative decline during ageing.
Project description:DNA damage response (DDR) is critically important for cell survival, genome maintenance, and its defect has been exploited therapeutically in cancer treatment. Many DDR-targeting agents have been generated and have entered the clinic and/or clinical trials. In order to provide a global and unbiased view of DDR network, we designed a focused CRISPR library targeting 365 DDR genes and performed CRISPR screens on the responses to several DDR inhibitors and DNA-damaging agents in 293A cells. With these screens, we determined responsive pathways enriched under treatment with different types of small-molecule agents. Additionally, we showed that POLE3/4-deficient cells displayed enhanced sensitivity to an ATR inhibitor, a PARP inhibitor, and camptothecin. Moreover, by performing DDR screens in isogenic TP53 wild-type and TP53 knock-out cell lines, our results suggest that the performance of our CRISPR DDR dropout screens is independent of TP53 status. Collectively, our findings indicate that CRISPR DDR screens can be used to identify potential targets of small-molecule drugs and reveal that TP53 status does not affect the outcome of these screens.
Project description:CD40 has major roles in B cell development, activation, and germinal center responses. CD40 hypoactivity causes immunodeficiency whereas its overexpression causes autoimmunity and lymphomagenesis. To systematically identify B cell autonomous CD40 regulators, we use CRISPR/Cas9 genome-scale screens in Daudi B cells stimulated by multimeric CD40 ligand. These highlight known CD40 pathway components and reveal multiple additional mechanisms regulating CD40. The nuclear ubiquitin ligase FBXO11 supports CD40 expression by targeting repressors CTBP1 and BCL6. FBXO11 knockout decreases primary B cell CD40 abundance and impairs class-switch recombination, suggesting that frequent lymphoma monoallelic FBXO11 mutations may balance BCL6 increase with CD40 loss. At the mRNA level, CELF1 controls exon splicing critical for CD40 activity, while the N6-adenosine methyltransferase WTAP negatively regulates CD40 mRNA abundance. At the protein level, ESCRT negatively regulates activated CD40 levels while the negative feedback phosphatase DUSP10 limits downstream MAPK responses. These results serve as a resource for future studies and highlight potential therapeutic targets.