RESUMO
The Hippo pathway plays a central role in tissue development and homeostasis. However, the function of Hippo in pancreatic endocrine development remains obscure. Here, we generated novel conditional genetically engineered mouse models to examine the roles of Hippo pathway-mediated YAP1/TAZ inhibition in the development stages of endocrine specification and differentiation. While YAP1 protein was localized to the nuclei in bipotent progenitor cells, Neurogenin 3 expressing endocrine progenitors completely lost YAP1 expression. Using genetically engineered mouse models, we found that inactivation of YAP1 requires both an intact Hippo pathway and Neurogenin 3 protein. Gene deletion of Lats1 and 2 kinases (Lats1&2) in endocrine progenitor cells of developing mouse pancreas using Neurog3Cre blocked endocrine progenitor cell differentiation and specification, resulting in reduced islets size and a disorganized pancreas at birth. Loss of Lats1&2 in Neurogenin 3 expressing cells activated YAP1/TAZ transcriptional activity and recruited macrophages to the developing pancreas. These defects were rescued by deletion of Yap1/Wwtr1 genes, suggesting that tight regulation of YAP1/TAZ by Hippo signaling is crucial for pancreatic endocrine specification. In contrast, deletion of Lats1&2 using ß-cell-specific Ins1CreER resulted in a phenotypically normal pancreas, indicating that Lats1&2 are indispensable for differentiation of endocrine progenitors but not for that of ß-cells. Our results demonstrate that loss of YAP1/TAZ expression in the pancreatic endocrine compartment is not a passive consequence of endocrine specification. Rather, Hippo pathway-mediated inhibition of YAP1/TAZ in endocrine progenitors is a prerequisite for endocrine specification and differentiation.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal , Diferenciação Celular , Proteínas Serina-Treonina Quinases , Transdução de Sinais , Proteínas de Sinalização YAP , Animais , Proteínas de Sinalização YAP/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Proteínas Adaptadoras de Transdução de Sinal/genética , Camundongos , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Serina-Treonina Quinases/genética , Via de Sinalização Hippo , Proteínas de Ciclo Celular/metabolismo , Proteínas de Ciclo Celular/genética , Fatores de Transcrição Hélice-Alça-Hélice Básicos/metabolismo , Fatores de Transcrição Hélice-Alça-Hélice Básicos/genética , Proteínas do Tecido Nervoso/metabolismo , Proteínas do Tecido Nervoso/genética , Transativadores/metabolismo , Transativadores/genética , Ilhotas Pancreáticas/metabolismo , Ilhotas Pancreáticas/embriologia , Fatores de Transcrição/metabolismo , Fatores de Transcrição/genética , Proteínas com Motivo de Ligação a PDZ com Coativador Transcricional/metabolismo , Fosfoproteínas/metabolismo , Fosfoproteínas/genética , Aciltransferases , Proteínas Supressoras de TumorRESUMO
Simple, efficient and well-tolerated delivery of CRISPR genome editing systems into primary cells remains a major challenge. Here we describe an engineered Peptide-Assisted Genome Editing (PAGE) CRISPR-Cas system for rapid and robust editing of primary cells with minimal toxicity. The PAGE system requires only a 30-min incubation with a cell-penetrating Cas9 or Cas12a and a cell-penetrating endosomal escape peptide to achieve robust single and multiplex genome editing. Unlike electroporation-based methods, PAGE gene editing has low cellular toxicity and shows no significant transcriptional perturbation. We demonstrate rapid and efficient editing of primary cells, including human and mouse T cells, as well as human hematopoietic progenitor cells, with editing efficiencies upwards of 98%. PAGE provides a broadly generalizable platform for next-generation genome engineering in primary cells.
Assuntos
Sistemas CRISPR-Cas , Edição de Genes , Humanos , Animais , Camundongos , Edição de Genes/métodos , Sistemas CRISPR-Cas/genética , Eletroporação , Células-Tronco HematopoéticasRESUMO
The switch from fetal hemoglobin (HbF) to adult hemoglobin (HbA) is a paradigm for developmental gene expression control with relevance to sickle cell disease and ß-thalassemia. Polycomb repressive complex (PRC) proteins regulate this switch, and an inhibitor of PRC2 has entered a clinical trial for HbF activation. Yet, how PRC complexes function in this process, their target genes, and relevant subunit composition are unknown. Here, we identified the PRC1 subunit BMI1 as a novel HbF repressor. We uncovered the RNA binding proteins LIN28B, IGF2BP1, and IGF2BP3 genes as direct BMI1 targets, and demonstrate that they account for the entirety of BMI1's effect on HbF regulation. BMI1 functions as part of the canonical PRC1 (cPRC1) subcomplex as revealed by the physical and functional dissection of BMI1 protein partners. Lastly, we demonstrate that BMI1/cPRC1 acts in concert with PRC2 to repress HbF through the same target genes. Our study illuminates how PRC silences HbF, highlighting an epigenetic mechanism involved in hemoglobin switching.
Assuntos
Hemoglobina Fetal , Complexo Repressor Polycomb 1 , Proteínas do Grupo Polycomb , Hemoglobina Fetal/genética , Complexo Repressor Polycomb 1/genética , Complexo Repressor Polycomb 1/metabolismoRESUMO
The fetal-to-adult switch in hemoglobin production is a model of developmental gene control with relevance to the treatment of hemoglobinopathies. The expression of transcription factor BCL11A, which represses fetal ß-type globin (HBG) genes in adult erythroid cells, is predominantly controlled at the transcriptional level but the underlying mechanism is unclear. We identify HIC2 as a repressor of BCL11A transcription. HIC2 and BCL11A are reciprocally expressed during development. Forced expression of HIC2 in adult erythroid cells inhibits BCL11A transcription and induces HBG expression. HIC2 binds to erythroid BCL11A enhancers to reduce chromatin accessibility and binding of transcription factor GATA1, diminishing enhancer activity and enhancer-promoter contacts. DNA-binding and crystallography studies reveal direct steric hindrance as one mechanism by which HIC2 inhibits GATA1 binding at a critical BCL11A enhancer. Conversely, loss of HIC2 in fetal erythroblasts increases enhancer accessibility, GATA1 binding and BCL11A transcription. HIC2 emerges as an evolutionarily conserved regulator of hemoglobin switching via developmental control of BCL11A.
Assuntos
Hemoglobinas , Fatores de Transcrição Kruppel-Like , Proteínas Repressoras , Proteínas Supressoras de Tumor , Proteínas de Transporte/genética , Células Eritroides/metabolismo , Hemoglobinas/genética , Humanos , Fatores de Transcrição Kruppel-Like/metabolismo , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo , Fatores de Transcrição/genética , Fatores de Transcrição/metabolismo , Proteínas Supressoras de Tumor/metabolismo , Globinas beta/genética , Globinas beta/metabolismo , gama-Globinas/genéticaRESUMO
The mechanisms by which the fetal-type ß-globin-like genes HBG1 and HBG2 are silenced in adult erythroid precursor cells remain a fundamental question in human biology and have therapeutic relevance to sickle cell disease and ß-thalassemia. Here, we identify via a CRISPR-Cas9 genetic screen two members of the NFI transcription factor family-NFIA and NFIX-as HBG1/2 repressors. NFIA and NFIX are expressed at elevated levels in adult erythroid cells compared with fetal cells, and function cooperatively to repress HBG1/2 in cultured cells and in human-to-mouse xenotransplants. Genomic profiling, genome editing and DNA binding assays demonstrate that the potent concerted activity of NFIA and NFIX is explained in part by their ability to stimulate the expression of BCL11A, a known silencer of the HBG1/2 genes, and in part by directly repressing the HBG1/2 genes. Thus, NFI factors emerge as versatile regulators of the fetal-to-adult switch in ß-globin production.
Assuntos
Hemoglobina Fetal , gama-Globinas , Animais , Proteínas de Transporte/genética , Células Eritroides/metabolismo , Hemoglobina Fetal/genética , Hemoglobina Fetal/metabolismo , Edição de Genes , Camundongos , Fatores de Transcrição NFI/genética , Fatores de Transcrição NFI/metabolismo , Fatores de Transcrição/genética , Globinas beta/genética , Globinas beta/metabolismo , gama-Globinas/genética , gama-Globinas/metabolismoRESUMO
Metazoan transcription factors typically regulate large numbers of genes. Here we identify via a CRISPR-Cas9 genetic screen ZNF410, a pentadactyl DNA-binding protein that in human erythroid cells directly activates only a single gene, the NuRD component CHD4. Specificity is conveyed by two highly evolutionarily conserved clusters of ZNF410 binding sites near the CHD4 gene with no counterparts elsewhere in the genome. Loss of ZNF410 in adult-type human erythroid cell culture systems and xenotransplantation settings diminishes CHD4 levels and derepresses the fetal hemoglobin genes. While previously known to be silenced by CHD4, the fetal globin genes are exposed here as among the most sensitive to reduced CHD4 levels.. In vitro DNA binding assays and crystallographic studies reveal the ZNF410-DNA binding mode. ZNF410 is a remarkably selective transcriptional activator in erythroid cells, and its perturbation might offer new opportunities for treatment of hemoglobinopathies.
Assuntos
DNA/genética , Células Precursoras Eritroides/metabolismo , Hemoglobina Fetal/genética , Complexo Mi-2 de Remodelação de Nucleossomo e Desacetilase/genética , Fatores de Transcrição/genética , Animais , Sítios de Ligação , Células COS , Sistemas CRISPR-Cas , Chlorocebus aethiops , DNA/metabolismo , Células Precursoras Eritroides/citologia , Células Precursoras Eritroides/transplante , Sangue Fetal/citologia , Sangue Fetal/metabolismo , Hemoglobina Fetal/metabolismo , Feto , Edição de Genes , Células HEK293 , Xenoenxertos , Humanos , Complexo Mi-2 de Remodelação de Nucleossomo e Desacetilase/química , Complexo Mi-2 de Remodelação de Nucleossomo e Desacetilase/metabolismo , Camundongos , Modelos Moleculares , Células-Tronco Embrionárias Murinas/citologia , Ligação Proteica , Conformação Proteica em alfa-Hélice , Conformação Proteica em Folha beta , Domínios e Motivos de Interação entre Proteínas , Fatores de Transcrição/química , Fatores de Transcrição/metabolismo , Ativação TranscricionalRESUMO
Reactivation of fetal hemoglobin remains a critical goal in the treatment of patients with sickle cell disease and ß-thalassemia. Previously, we discovered that silencing of the fetal γ-globin gene requires the erythroid-specific eIF2α kinase heme-regulated inhibitor (HRI), suggesting that HRI might present a pharmacologic target for raising fetal hemoglobin levels. Here, via a CRISPR-Cas9-guided loss-of-function screen in human erythroblasts, we identify transcription factor ATF4, a known HRI-regulated protein, as a novel γ-globin regulator. ATF4 directly stimulates transcription of BCL11A, a repressor of γ-globin transcription, by binding to its enhancer and fostering enhancer-promoter contacts. Notably, HRI-deficient mice display normal Bcl11a levels, suggesting species-selective regulation, which we explain here by demonstrating that the analogous ATF4 motif at the murine Bcl11a enhancer is largely dispensable. Our studies uncover a linear signaling pathway from HRI to ATF4 to BCL11A to γ-globin and illustrate potential limits of murine models of globin gene regulation.
Assuntos
Fator 4 Ativador da Transcrição/genética , Hemoglobina Fetal/genética , Proteínas Repressoras/genética , eIF-2 Quinase/genética , Anemia Falciforme/sangue , Anemia Falciforme/genética , Anemia Falciforme/terapia , Animais , Sistemas CRISPR-Cas , Células Cultivadas , Elementos Facilitadores Genéticos , Eritroblastos/metabolismo , Regulação da Expressão Gênica , Inativação Gênica , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteínas Serina-Treonina Quinases/deficiência , Proteínas Serina-Treonina Quinases/genética , Especificidade da Espécie , Talassemia beta/sangue , Talassemia beta/genética , Talassemia beta/terapia , gama-Globinas/biossíntese , gama-Globinas/genéticaRESUMO
AIMS/HYPOTHESIS: Better understanding of how genetic and epigenetic components control beta cell differentiation and function is key to the discovery of novel therapeutic approaches to prevent beta cell dysfunction and failure in the progression of type 2 diabetes. Our goal was to elucidate the role of histone deacetylase sirtuin 6 (SIRT6) in beta cell development and homeostasis. METHODS: Sirt6 endocrine progenitor cell conditional knockout and beta cell-specific knockout mice were generated using the Cre-loxP system. Mice were assayed for islet morphology, glucose tolerance, glucose-stimulated insulin secretion and susceptibility to streptozotocin. Transcriptional regulatory functions of SIRT6 in primary islets were evaluated by RNA-Seq analysis. Reverse transcription-quantitative (RT-q)PCR and immunoblot were used to verify and investigate the gene expression changes. Chromatin occupancies of SIRT6, H3K9Ac, H3K56Ac and active RNA polymerase II were evaluated by chromatin immunoprecipitation. RESULTS: Deletion of Sirt6 in pancreatic endocrine progenitor cells did not affect endocrine morphology, beta cell mass or insulin production but did result in glucose intolerance and defective glucose-stimulated insulin secretion in mice. Conditional deletion of Sirt6 in adult beta cells reproduced the insulin secretion defect. Loss of Sirt6 resulted in aberrant upregulation of thioredoxin-interacting protein (TXNIP) in beta cells. SIRT6 deficiency led to increased acetylation of histone H3 lysine residue at 9 (H3K9Ac), acetylation of histone H3 lysine residue at 56 (H3K56Ac) and active RNA polymerase II at the promoter region of Txnip. SIRT6-deficient beta cells exhibited a time-dependent increase in H3K9Ac, H3K56Ac and TXNIP levels. Finally, beta cell-specific SIRT6-deficient mice showed increased sensitivity to streptozotocin. CONCLUSIONS/INTERPRETATION: Our results reveal that SIRT6 suppresses Txnip expression in beta cells via deacetylation of histone H3 and plays a critical role in maintaining beta cell function and viability. DATA AVAILABILITY: Sequence data have been deposited in the National Institutes of Health (NIH) Gene Expression Omnibus (GEO) with the accession code GSE104161.
Assuntos
Proteínas de Transporte/genética , Células Secretoras de Insulina/fisiologia , Sirtuínas/genética , Tiorredoxinas/genética , Acetilação , Animais , Glicemia/análise , Glicemia/metabolismo , Proteínas de Transporte/fisiologia , Diferenciação Celular , Diabetes Mellitus Tipo 2/sangue , Modelos Animais de Doenças , Progressão da Doença , Feminino , Deleção de Genes , Glucose/metabolismo , Insulina/metabolismo , Células Secretoras de Insulina/citologia , Ilhotas Pancreáticas , Masculino , Camundongos , Camundongos Knockout , Pâncreas/fisiologia , Análise de Sequência de RNA , Sirtuínas/fisiologia , Estreptozocina/farmacologia , Tiorredoxinas/fisiologiaRESUMO
Although Oct4 is known as a critical transcription factor involved in maintaining "stemness", its role in tumor metastasis is still controversial. Herein, we overexpressed and silenced Oct4 expression in two breast cancer cell lines, MDA-MB-231 and 4T1, separately. Our data showed that ectopic overexpression of Oct4 suppressed cell migration and invasion in vitro and the formation of metastatic lung nodules in vivo. Conversely, Oct4 downregulation increased the metastatic potential of breast cancer cells both in vitro and in vivo. Furthermore, we identified Rnd1 as the downstream target of Oct4 by ribonucleic acid sequencing (RNA-seq) analysis, which was significantly downregulated upon Oct4 overexpression. Chromatin immunoprecipitation assays revealed the binding of Oct4 to the promoter region of Rnd1 by ectopic overexpression of Oct4. Dual luciferase assays indicated that Oct4 overexpression suppressed transcriptional activity of the Rnd1 promoter. Moreover, overexpression of Rnd1 partially rescued the inhibitory effects of Oct4 on the migration and invasion of breast cancer cells. Overexpression of Rnd1 counteracted the influence of Oct4 on the formation of cell adhesion and lamellipodia, which implied a potential underlying mechanism involving Rnd1. In addition, we also found that overexpression of Oct4 led to an elevation of E-cadherin expression, even in 4T1 cells that possess a relatively high basal level of E-cadherin. Rnd1 overexpression impaired the promoting effects of Oct4 on E-cadherin expression in MDA-MB-231 cells. These results suggest that Oct4 affects the metastatic potential of breast cancer cells through Rnd1-mediated effects that influence cell motility and E-cadherin expression.
RESUMO
Negative elongation factor (NELF) is known to enforce promoter-proximal pausing of RNA polymerase II (Pol II), a pervasive phenomenon observed across multicellular genomes. However, the physiological impact of NELF on tissue homeostasis remains unclear. Here, we show that whole-body conditional deletion of the B subunit of NELF (NELF-B) in adult mice results in cardiomyopathy and impaired response to cardiac stress. Tissue-specific knockout of NELF-B confirms its cell-autonomous function in cardiomyocytes. NELF directly supports transcription of those genes encoding rate-limiting enzymes in fatty acid oxidation (FAO) and the tricarboxylic acid (TCA) cycle. NELF also shares extensively transcriptional target genes with peroxisome proliferator-activated receptor α (PPARα), a master regulator of energy metabolism in the myocardium. Mechanistically, NELF helps stabilize the transcription initiation complex at the metabolism-related genes. Our findings strongly indicate that NELF is part of the PPARα-mediated transcription regulatory network that maintains metabolic homeostasis in cardiomyocytes.
Assuntos
Miócitos Cardíacos/metabolismo , Fatores de Transcrição/metabolismo , Animais , Cardiomiopatias/genética , Cardiomiopatias/metabolismo , Ecocardiografia , Metabolismo Energético/genética , Homeostase , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Camundongos Transgênicos , Miócitos Cardíacos/citologia , PPAR alfa/genética , PPAR alfa/metabolismo , RNA Polimerase II/metabolismo , Fatores de Transcrição/genética , Transcrição GênicaRESUMO
The stem cell-related transcription factor Oct4 regulates tumor proliferation and apoptosis, but its role in tumor migration and invasion is still undefined. Here, we compared Oct4 expression in MCF-7 and MDA-MB-231 cells, two breast cancer cell lines with similar epithelial origins, but distinct invasive and metastatic characteristics. We found MCF-7 cells to express very high levels of Oct4, while no obvious expression was detected in MDA-MB-231 cells. We then downregulated Oct4 expression using small interfering RNA (siRNA) to explore its effects on migration and invasion. Transwell assays showed that silencing Oct4 in MCF-7 cells improved their migration and invasion capabilities. Reverse-transcriptase PCR and western blots showed that E-cadherin expression decreased, and α-smooth muscle actin expression increased with Oct4 downregulation, which suggests that epithelial-to-mesenchymal transition (EMT) occurred. A potent EMT stimulus, TGF-ß1, significantly inhibited Oct4 expression in both dose- and time course-dependent manners. Silencing Oct4 also upregulated expression of two major components of store-operated Ca(2+) entry channels (SOCs), STIM1 and Orai1, and enhanced SOC-directed Ca(2+) influx. Silencing STIM1 blocked the Ca(2+) influx and rescued the EMT initiated by Oct4 downregulation. In conclusion, silencing Oct4 promotes invasion and metastasis in breast cancer cells by inducing EMT. This effect may be related to SOCs-directed enhancement of Ca(2+) influx.