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Angiogenesis, the process by which endothelial cells (ECs) form new blood vessels from existing ones, is intimately linked to the tissue’s metabolic milieu and often occurs at nutrient-deficient sites. However, ECs rely on sufficient metabolic resources to support growth and proliferation. How endothelial nutrient acquisition and usage are regulated is unknown. Here we show that these processes are instructed by Yes-associated protein 1 (YAP)/WW domain-containing transcription regulator 1 (WWTR1/TAZ)-transcriptional enhanced associate domain (TEAD): a transcriptional module whose function is highly responsive to changes in the tissue environment. ECs lacking YAP/TAZ or their transcriptional partners, TEAD1, 2 and 4 fail to divide, resulting in stunted vascular growth in mice. Conversely, activation of TAZ, the more abundant paralogue in ECs, boosts proliferation, leading to vascular hyperplasia. We find that YAP/TAZ promote angiogenesis by fuelling nutrient-dependent mTORC1 signalling. By orchestrating the transcription of a repertoire of cell-surface transporters, including the large neutral amino acid transporter SLC7A5, YAP/TAZ-TEAD stimulate the import of amino acids and other essential nutrients, thereby enabling mTORC1 activation. Dissociating mTORC1 from these nutrient inputs—elicited by the loss of Rag GTPases—inhibits mTORC1 activity and prevents YAP/TAZ-dependent vascular growth. Together, these findings define a pivotal role for YAP/TAZ-TEAD in controlling endothelial mTORC1 and illustrate the essentiality of coordinated nutrient fluxes in the vasculature.
Current technologies used to generate CRISPR/Cas gene perturbation reagents are labor intense and require multiple ligation and cloning steps. Furthermore, increasing gRNA sequence diversity negatively affects gRNA distribution, leading to libraries of heterogeneous quality. Here, we present a rapid and cloning-free mutagenesis technology that can efficiently generate covalently-closed-circular-synthesized (3Cs) CRISPR/Cas gRNA reagents and that uncouples sequence diversity from sequence distribution. We demonstrate the fidelity and performance of 3Cs reagents by tailored targeting of all human deubiquitinating enzymes (DUBs) and identify their essentiality for cell fitness. To explore high-content screening, we aimed to generate the largest up-to-date gRNA library that can be used to interrogate the coding and noncoding human genome and simultaneously to identify genes, predicted promoter flanking regions, transcription factors and CTCF binding sites that are linked to doxorubicin resistance. Our 3Cs technology enables fast and robust generation of bias-free gene perturbation libraries with yet unmatched diversities and should be considered an alternative to established technologies.
Long non-coding RNAs (lncRNAs) contribute to cardiac (patho)physiology. Aging is the major risk factor for cardiovascular disease with cardiomyocyte apoptosis as one underlying cause. Here, we report the identification of the aging-regulated lncRNA Sarrah (ENSMUST00000140003) that is anti-apoptotic in cardiomyocytes. Importantly, loss of SARRAH (OXCT1-AS1) in human engineered heart tissue results in impaired contractile force development. SARRAH directly binds to the promoters of genes downregulated after SARRAH silencing via RNA-DNA triple helix formation and cardiomyocytes lacking the triple helix forming domain of Sarrah show an increase in apoptosis. One of the direct SARRAH targets is NRF2, and restoration of NRF2 levels after SARRAH silencing partially rescues the reduction in cell viability. Overexpression of Sarrah in mice shows better recovery of cardiac contractile function after AMI compared to control mice. In summary, we identified the anti-apoptotic evolutionary conserved lncRNA Sarrah, which is downregulated by aging, as a regulator of cardiomyocyte survival.
The transcriptional regulator far upstream binding protein 1 (FUBP1) is essential for fetal and adult hematopoietic stem cell (HSC) self-renewal, and the constitutive absence of FUBP1 activity during early development leads to embryonic lethality in homozygous mutant mice. To investigate the role of FUBP1 in murine embryonic stem cells (ESCs) and in particular during differentiation into hematopoietic lineages, we generated Fubp1 knockout (KO) ESC clones using CRISPR/Cas9 technology. Although FUBP1 is expressed in undifferentiated ESCs and during spontaneous differentiation following aggregation into embryoid bodies (EBs), absence of FUBP1 did not affect ESC maintenance. Interestingly, we observed a delayed differentiation of FUBP1-deficient ESCs into the mesoderm germ layer, as indicated by impaired expression of several mesoderm markers including Brachyury at an early time point of ESC differentiation upon aggregation to EBs. Coculture experiments with OP9 cells in the presence of erythropoietin revealed a diminished differentiation capacity of Fubp1 KO ESCs into the erythroid lineage. Our data showed that FUBP1 is important for the onset of mesoderm differentiation and maturation of hematopoietic progenitor cells into the erythroid lineage, a finding that is supported by the phenotype of FUBP1-deficient mice.
Drug resistance is a commonly unavoidable consequence of cancer treatment that results in therapy failure and disease relapse. Intrinsic (pre-existing) or acquired resistance mechanisms can be drug-specific or be applicable to multiple drugs, resulting in multidrug resistance. The presence of drug resistance is, however, tightly coupled to changes in cellular homeostasis, which can lead to resistance-coupled vulnerabilities. Unbiased gene perturbations through RNAi and CRISPR technologies are invaluable tools to establish genotype-to-phenotype relationships at the genome scale. Moreover, their application to cancer cell lines can uncover new vulnerabilities that are associated with resistance mechanisms. Here, we discuss targeted and unbiased RNAi and CRISPR efforts in the discovery of drug resistance mechanisms by focusing on first-in-line chemotherapy and their enforced vulnerabilities, and we present a view forward on which measures should be taken to accelerate their clinical translation.
Das adaptive Immunsystem CRISPR (engl. „clustered regularly interspaced short palindromic repeats“) revolutioniert die medizinische Grundlagenforschung. Die Einfachheit, Präzision und Vielseitigkeit der CRISPR-Technologie ermöglicht es nicht nur, Gene gezielt aus- oder einzuschalten, sondern auch zu korrigieren. Die Hoffnung richtet sich auf eine CRISPR-vermittelte Gentherapie, um krebsverursachende Mutationen gezielt zu korrigieren und somit Tumorwachstum zu verhindern oder therapieren zu können. Technisch ist dies zeitnah vorstellbar, doch ethische und rechtliche Rahmenbedingungen sollten dringend vorab geklärt werden. Die durch Gene Editing aufgeworfenen ethischen und rechtlichen Fragen werden zwar schon seit vielen Jahren diskutiert; durch die nun eingetretene rapide technische Entwicklung stellen sie sich jedoch in neuer Dringlichkeit. Eine umfassende ethische Bewertung der Erforschung und möglichen Anwendung ist daher geboten, einschließlich Fragen der Wissenschaftsethik und -kultur sowie längerfristiger potenzieller sozialer Konsequenzen der CRISPR-Technologie. Rechtlich unterliegt die Gentherapie den allgemeinen arzneimittelrechtlichen Regelungen, die Keimbahntherapie dagegen ist in Deutschland verboten. Auf Dauer und angesichts der erwartbaren weltweiten Entwicklung ist dieses Verbot jedoch zu hinterfragen. In der vorliegenden Arbeit erläutern die Autoren technische, ethische und rechtliche Aspekte des Gene Editing in der Krebsforschung und -therapie und diskutieren die daraus resultierenden Fragen: „Was kann, soll und darf gemacht werden?“.
