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1.
Diabetologia ; 2021 Feb 09.
Artigo em Inglês | MEDLINE | ID: mdl-33558985

RESUMO

AIMS/HYPOTHESIS: Acute hyperglycaemia stimulates pancreatic beta cell proliferation in the mouse whereas chronic hyperglycaemia appears to be toxic. We hypothesise that this toxic effect is mediated by increased beta cell workload, unrelated to hyperglycaemia per se. METHODS: To test this hypothesis, we developed a novel mouse model of cell-autonomous increased beta cell glycolytic flux caused by a conditional heterozygous beta cell-specific mutation that activates glucokinase (GCK), mimicking key aspects of the rare human genetic disease GCK-congenital hyperinsulinism. RESULTS: In the mutant mice, we observed random and fasting hypoglycaemia (random 4.5-5.4 mmol/l and fasting 3.6 mmol/l) that persisted for 15 months. GCK activation led to increased beta cell proliferation as measured by Ki67 expression (2.7% vs 1.5%, mutant and wild-type (WT), respectively, p < 0.01) that resulted in a 62% increase in beta cell mass in young mice. However, by 8 months of age, mutant mice developed impaired glucose tolerance, which was associated with decreased absolute beta cell mass from 2.9 mg at 1.5 months to 1.8 mg at 8 months of age, with preservation of individual beta cell function. Impaired glucose tolerance was further exacerbated by a high-fat/high-sucrose diet (AUC 1796 vs 966 mmol/l × min, mutant and WT, respectively, p < 0.05). Activation of GCK was associated with an increased DNA damage response and an elevated expression of Chop, suggesting metabolic stress as a contributor to beta cell death. CONCLUSIONS/INTERPRETATION: We propose that increased workload-driven biphasic beta cell dynamics contribute to decreased beta cell function observed in long-standing congenital hyperinsulinism and type 2 diabetes.

2.
Mol Metab ; : 101193, 2021 Feb 18.
Artigo em Inglês | MEDLINE | ID: mdl-33610858

RESUMO

OBJECTIVE: While the molecular events controlling insulin secretion from ß-cells have been documented in detail, the exact mechanisms governing glucagon release by α-cells are understood only partially. This is a critical knowledge gap, as the normal suppression of glucagon secretion by elevated glucose levels fails in Type 2 Diabetes (T2D) patients, contributing to hyperglycemia through stimulation of hepatic glucose production. A critical role of glycolytic flux in regulating glucagon secretion was supported by recent studies in which manipulation of the activity and expression of the glycolytic enzyme glucokinase altered the setpoint for glucose-suppression of glucagon secretion (GSGS). Given this precedent, we hypothesized that genetic activation of glucokinase specifically in α-cells would enhance GSGS and mitigate T2D hyperglucagonemia. METHODS: We derived an inducible, α-cell-specific glucokinase activating mutant mouse model (GckLoxPGck∗/LoxPGck∗; Gcg-CreERT2; henceforth referred to as "α-mutGCK") in which the wild-type glucokinase gene (GCK) is conditionally replaced with a glucokinase mutant allele containing the ins454A activating mutation (Gck*), a mutation that increases the affinity of glucokinase for glucose by almost seven-fold. The effects of α-cell GCK activation on glucose homeostasis, hormone secretion, islet morphology, and islet numbers were assessed using both in vivo and ex vivo assays. Additionally, the effect of α-cell GCK activation on GSGS was investigated under diabetogenic conditions of high fat diet (HFD) feeding that dysregulate glucagon secretion. RESULTS: Our study shows that α-mutGCK mice have enhanced GSGS in vivo and ex vivo, independent of alterations in insulin levels and secretion, islet hormone content, islet morphology, or islet number. α-mutGCK mice maintained on HFD displayed improvements in glucagonemia compared to controls, which developed the expected obesity, glucose intolerance, elevated fasting blood glucose, hyperinsulinemia, and hyperglucagonemia. CONCLUSIONS: Using our novel α-cell specific activation of GCK mouse model, we have provided additional support to demonstrate that the glycolytic enzyme glucokinase is a key determinant in glucose sensing within α-cells to regulate glucagon secretion. Our results contribute to our fundamental understanding of α-cell biology by providing greater insight into the regulation of glucagon secretion through α-cell intrinsic mechanisms via glucokinase. Furthermore, our HFD results underscore the potential of glucokinase as a druggable target which, given the ongoing development of allosteric glucokinase activators (GKAs) for T2D treatment, could help mitigate hyperglucagonemia and potentially improve blood glucose homeostasis.

3.
Cell ; 184(3): 827-839.e14, 2021 Feb 04.
Artigo em Inglês | MEDLINE | ID: mdl-33545036

RESUMO

Ahmed and colleagues recently described a novel hybrid lymphocyte expressing both a B and T cell receptor, termed double expresser (DE) cells. DE cells in blood of type 1 diabetes (T1D) subjects were present at increased numbers and enriched for a public B cell clonotype. Here, we attempted to reproduce these findings. While we could identify DE cells by flow cytometry, we found no association between DE cell frequency and T1D status. We were unable to identify the reported public B cell clone, or any similar clone, in bulk B cells or sorted DE cells from T1D subjects or controls. We also did not observe increased usage of the public clone VH or DH genes in B cells or in sorted DE cells. Taken together, our findings suggest that DE cells and their alleged public clonotype are not enriched in T1D. This Matters Arising paper is in response to Ahmed et al. (2019), published in Cell. See also the response by Ahmed et al. (2021), published in this issue.

4.
JCI Insight ; 2021 Feb 23.
Artigo em Inglês | MEDLINE | ID: mdl-33621209

RESUMO

Studies of human hepatitis B virus (HBV) immune pathogenesis are hampered by limited access to liver tissues and technologies for detailed analyses. Here, utilizing imaging mass cytometry (IMC) to simultaneously detect 30 immune, viral and structural markers in liver biopsies from patients with HBeAg+ chronic hepatitis B, we provide novel comprehensive visualization, quantitation and phenotypic characterizations of hepatic adaptive and innate immune subsets that correlated with hepatocellular injury, histological fibrosis and age. We further show marked correlations between adaptive and innate immune cell frequencies and phenotype, highlighting complex immune interactions within the hepatic microenvironment with relevance to HBV pathogenesis.

5.
Nat Med ; 27(1): 66-72, 2021 01.
Artigo em Inglês | MEDLINE | ID: mdl-33432171

RESUMO

The clinical impact of rare loss-of-function variants has yet to be determined for most genes. Integration of DNA sequencing data with electronic health records (EHRs) could enhance our understanding of the contribution of rare genetic variation to human disease1. By leveraging 10,900 whole-exome sequences linked to EHR data in the Penn Medicine Biobank, we addressed the association of the cumulative effects of rare predicted loss-of-function variants for each individual gene on human disease on an exome-wide scale, as assessed using a set of diverse EHR phenotypes. After discovering 97 genes with exome-by-phenome-wide significant phenotype associations (P < 10-6), we replicated 26 of these in the Penn Medicine Biobank, as well as in three other medical biobanks and the population-based UK Biobank. Of these 26 genes, five had associations that have been previously reported and represented positive controls, whereas 21 had phenotype associations not previously reported, among which were genes implicated in glaucoma, aortic ectasia, diabetes mellitus, muscular dystrophy and hearing loss. These findings show the value of aggregating rare predicted loss-of-function variants into 'gene burdens' for identifying new gene-disease associations using EHR phenotypes in a medical biobank. We suggest that application of this approach to even larger numbers of individuals will provide the statistical power required to uncover unexplored relationships between rare genetic variation and disease phenotypes.


Assuntos
Registros Eletrônicos de Saúde , Exoma , Genótipo , Fenótipo , Idoso , Biologia Computacional , Feminino , Estudo de Associação Genômica Ampla , Humanos , Masculino , Polimorfismo de Nucleotídeo Único , Sequenciamento Completo do Exoma
6.
Nat Commun ; 12(1): 346, 2021 01 12.
Artigo em Inglês | MEDLINE | ID: mdl-33436641

RESUMO

Anti-PD-1 therapy is used as a front-line treatment for many cancers, but mechanistic insight into this therapy resistance is still lacking. Here we generate a humanized (Hu)-mouse melanoma model by injecting fetal liver-derived CD34+ cells and implanting autologous thymus in immune-deficient NOD-scid IL2Rγnull (NSG) mice. Reconstituted Hu-mice are challenged with HLA-matched melanomas and treated with anti-PD-1, which results in restricted tumor growth but not complete regression. Tumor RNA-seq, multiplexed imaging and immunohistology staining show high expression of chemokines, as well as recruitment of FOXP3+ Treg and mast cells, in selective tumor regions. Reduced HLA-class I expression and CD8+/Granz B+ T cells homeostasis are observed in tumor regions where FOXP3+ Treg and mast cells co-localize, with such features associated with resistance to anti-PD-1 treatment. Combining anti-PD-1 with sunitinib or imatinib results in the depletion of mast cells and complete regression of tumors. Our results thus implicate mast cell depletion for improving the efficacy of anti-PD-1 therapy.


Assuntos
Resistencia a Medicamentos Antineoplásicos , Linfócitos do Interstício Tumoral/imunologia , Mastócitos/imunologia , Receptor de Morte Celular Programada 1/antagonistas & inibidores , Animais , Linfócitos B/efeitos dos fármacos , Linfócitos B/imunologia , Resistencia a Medicamentos Antineoplásicos/efeitos dos fármacos , Humanos , Linfócitos do Interstício Tumoral/efeitos dos fármacos , Mastócitos/efeitos dos fármacos , Melanoma/imunologia , Melanoma/patologia , Melanoma/terapia , Camundongos Transgênicos , Receptor de Morte Celular Programada 1/metabolismo , Sunitinibe/farmacologia , Sunitinibe/uso terapêutico , Linfócitos T/efeitos dos fármacos , Linfócitos T/imunologia
7.
Cell Metab ; 32(6): 1028-1040.e4, 2020 12 01.
Artigo em Inglês | MEDLINE | ID: mdl-33207245

RESUMO

Isolated reports of new-onset diabetes in individuals with COVID-19 have led to the hypothesis that SARS-CoV-2 is directly cytotoxic to pancreatic islet ß cells. This would require binding and entry of SARS-CoV-2 into ß cells via co-expression of its canonical cell entry factors, angiotensin-converting enzyme 2 (ACE2) and transmembrane serine protease 2 (TMPRSS2); however, their expression in human pancreas has not been clearly defined. We analyzed six transcriptional datasets of primary human islet cells and found that ACE2 and TMPRSS2 were not co-expressed in single ß cells. In pancreatic sections, ACE2 and TMPRSS2 protein was not detected in ß cells from donors with and without diabetes. Instead, ACE2 protein was expressed in islet and exocrine tissue microvasculature and in a subset of pancreatic ducts, whereas TMPRSS2 protein was restricted to ductal cells. These findings reduce the likelihood that SARS-CoV-2 directly infects ß cells in vivo through ACE2 and TMPRSS2.

8.
bioRxiv ; 2020 Oct 20.
Artigo em Inglês | MEDLINE | ID: mdl-33106804

RESUMO

Reports of new-onset diabetes and diabetic ketoacidosis in individuals with COVID-19 have led to the hypothesis that SARS-CoV-2, the virus that causes COVID-19, is directly cytotoxic to pancreatic islet ß cells. This would require binding and entry of SARS-CoV-2 into host ß cells via cell surface co-expression of ACE2 and TMPRSS2, the putative receptor and effector protease, respectively. To define ACE2 and TMPRSS2 expression in the human pancreas, we examined six transcriptional datasets from primary human islet cells and assessed protein expression by immunofluorescence in pancreata from donors with and without diabetes. ACE2 and TMPRSS2 transcripts were low or undetectable in pancreatic islet endocrine cells as determined by bulk or single cell RNA sequencing, and neither protein was detected in α or ß cells from these donors. Instead, ACE2 protein was expressed in the islet and exocrine tissue microvasculature and also found in a subset of pancreatic ducts, whereas TMPRSS2 protein was restricted to ductal cells. The absence of significant ACE2 and TMPRSS2 co-expression in islet endocrine cells reduces the likelihood that SARS-CoV-2 directly infects pancreatic islet ß cells through these cell entry proteins.

9.
Diabetologia ; 63(10): 1966-1973, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32894306

RESUMO

For much of the last century, our knowledge regarding the pancreas in type 1 and type 2 diabetes was largely derived from autopsy studies of individuals with these disorders or investigations utilising rodent models of either disease. While many important insights emanated from these efforts, the mode for investigation has increasingly seen change due to the availability of transplant-quality organ-donor tissues, improvements in pancreatic imaging, advances in metabolic assessments of living patients, genetic analyses, technological advances for laboratory investigation and more. As a result, many long-standing notions regarding the role for and the changes that occur in the pancreas in individuals with these disorders have come under question, while, at the same time, new issues (e.g., beta cell persistence, disease heterogeneity, exocrine contributions) have arisen. In this article, we will consider the vital role of the pancreas in human health and physiology, including discussion of its anatomical features and dual (exocrine and endocrine) functions. Specifically, we convey changes that occur in the pancreas of those with either type 1 or type 2 diabetes, with careful attention to the facets that may contribute to the pathogenesis of either disorder. Finally, we discuss the emerging unknowns with the belief that understanding the role of the pancreas in type 1 and type 2 diabetes will lead to improvements in disease diagnosis, understanding of disease heterogeneity and optimisation of treatments at a personalised level. Graphical abstract.

10.
Nat Metab ; 2(10): 1013-1020, 2020 10.
Artigo em Inglês | MEDLINE | ID: mdl-32895576

RESUMO

The intrahepatic milieu is inhospitable to intraportal islet allografts1-3, limiting their applicability for the treatment of type 1 diabetes. Although the subcutaneous space represents an alternate, safe and easily accessible site for pancreatic islet transplantation, lack of neovascularization and the resulting hypoxic cell death have largely limited the longevity of graft survival and function and pose a barrier to the widespread adoption of islet transplantation in the clinic. Here we report the successful subcutaneous transplantation of pancreatic islets admixed with a device-free islet viability matrix, resulting in long-term euglycaemia in diverse immune-competent and immuno-incompetent animal models. We validate sustained normoglycaemia afforded by our transplantation methodology using murine, porcine and human pancreatic islets, and also demonstrate its efficacy in a non-human primate model of syngeneic islet transplantation. Transplantation of the islet-islet viability matrix mixture in the subcutaneous space represents a simple, safe and reproducible method, paving the way for a new therapeutic paradigm for type 1 diabetes.

11.
Mol Metab ; 42: 101057, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32739450

RESUMO

OBJECTIVE: Dedifferentiation of pancreatic ß-cells may reduce islet function in type 2 diabetes (T2D). However, the prevalence, plasticity and functional consequences of this cellular state remain unknown. METHODS: We employed single-cell RNAseq to detail the maturation program of α- and ß-cells during human ontogeny. We also compared islets from non-diabetic and T2D individuals. RESULTS: Both α- and ß-cells mature in part by repressing non-endocrine genes; however, α-cells retain hallmarks of an immature state, while ß-cells attain a full ß-cell specific gene expression program. In islets from T2D donors, both α- and ß-cells have a less mature expression profile, de-repressing the juvenile genetic program and exocrine genes and increasing expression of exocytosis, inflammation and stress response signalling pathways. These changes are consistent with the increased proportion of ß-cells displaying suboptimal function observed in T2D islets. CONCLUSIONS: These findings provide new insights into the molecular program underlying islet cell maturation during human ontogeny and the loss of transcriptomic maturity that occurs in islets of type 2 diabetics.

12.
Proc Natl Acad Sci U S A ; 117(29): 17177-17186, 2020 07 21.
Artigo em Inglês | MEDLINE | ID: mdl-32631996

RESUMO

Hepatocyte nuclear factor 4α (HNF4α) is a master regulator of liver function and a tumor suppressor in hepatocellular carcinoma (HCC). In this study, we explore the reciprocal negative regulation of HNF4α and cyclin D1, a key cell cycle protein in the liver. Transcriptomic analysis of cultured hepatocyte and HCC cells found that cyclin D1 knockdown induced the expression of a large network of HNF4α-regulated genes. Chromatin immunoprecipitation-sequencing (ChIP-seq) demonstrated that cyclin D1 inhibits the binding of HNF4α to thousands of targets in the liver, thereby diminishing the expression of associated genes that regulate diverse metabolic activities. Conversely, acute HNF4α deletion in the liver induces cyclin D1 and hepatocyte cell cycle progression; concurrent cyclin D1 ablation blocked this proliferation, suggesting that HNF4α maintains proliferative quiescence in the liver, at least, in part, via repression of cyclin D1. Acute cyclin D1 deletion in the regenerating liver markedly inhibited hepatocyte proliferation after partial hepatectomy, confirming its pivotal role in cell cycle progression in this in vivo model, and enhanced the expression of HNF4α target proteins. Hepatocyte cyclin D1 gene ablation caused markedly increased postprandial liver glycogen levels (in a HNF4α-dependent fashion), indicating that the cyclin D1-HNF4α axis regulates glucose metabolism in response to feeding. In AML12 hepatocytes, cyclin D1 depletion led to increased glucose uptake, which was negated if HNF4α was depleted simultaneously, and markedly elevated glycogen synthesis. To summarize, mutual repression by cyclin D1 and HNF4α coordinately controls the cell cycle machinery and metabolism in the liver.


Assuntos
Ciclo Celular/fisiologia , Ciclina D1/genética , Ciclina D1/metabolismo , Fator 4 Nuclear de Hepatócito/genética , Fator 4 Nuclear de Hepatócito/metabolismo , Fígado/metabolismo , Animais , Carcinoma Hepatocelular/metabolismo , Carcinoma Hepatocelular/patologia , Proteínas de Ciclo Celular/metabolismo , Linhagem Celular Tumoral , Proliferação de Células , Modelos Animais de Doenças , Feminino , Técnicas de Silenciamento de Genes , Hepatócitos/metabolismo , Hepatócitos/patologia , Regeneração Hepática/genética , Regeneração Hepática/fisiologia , Masculino , Camundongos Endogâmicos BALB C , Camundongos Knockout
14.
Nat Genet ; 52(7): 680-691, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32541925

RESUMO

We investigated type 2 diabetes (T2D) genetic susceptibility via multi-ancestry meta-analysis of 228,499 cases and 1,178,783 controls in the Million Veteran Program (MVP), DIAMANTE, Biobank Japan and other studies. We report 568 associations, including 286 autosomal, 7 X-chromosomal and 25 identified in ancestry-specific analyses that were previously unreported. Transcriptome-wide association analysis detected 3,568 T2D associations with genetically predicted gene expression in 687 novel genes; of these, 54 are known to interact with FDA-approved drugs. A polygenic risk score (PRS) was strongly associated with increased risk of T2D-related retinopathy and modestly associated with chronic kidney disease (CKD), peripheral artery disease (PAD) and neuropathy. We investigated the genetic etiology of T2D-related vascular outcomes in the MVP and observed statistical SNP-T2D interactions at 13 variants, including coronary heart disease (CHD), CKD, PAD and neuropathy. These findings may help to identify potential therapeutic targets for T2D and genomic pathways that link T2D to vascular outcomes.


Assuntos
Complicações do Diabetes/genética , Diabetes Mellitus Tipo 2/genética , Predisposição Genética para Doença , Afro-Americanos , Cromossomos Humanos X , Diabetes Mellitus Tipo 2/complicações , Diabetes Mellitus Tipo 2/tratamento farmacológico , Diabetes Mellitus Tipo 2/etnologia , Angiopatias Diabéticas/genética , Europa (Continente) , Feminino , Estudos de Associação Genética , Humanos , Hipoglicemiantes/uso terapêutico , Masculino , Polimorfismo de Nucleotídeo Único , Medição de Risco
15.
Genes Dev ; 34(15-16): 1039-1050, 2020 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-32561546

RESUMO

The FoxA transcription factors are critical for liver development through their pioneering activity, which initiates a highly complex regulatory network thought to become progressively resistant to the loss of any individual hepatic transcription factor via mutual redundancy. To investigate the dispensability of FoxA factors for maintaining this regulatory network, we ablated all FoxA genes in the adult mouse liver. Remarkably, loss of FoxA caused rapid and massive reduction in the expression of critical liver genes. Activity of these genes was reduced back to the low levels of the fetal prehepatic endoderm stage, leading to necrosis and lethality within days. Mechanistically, we found FoxA proteins to be required for maintaining enhancer activity, chromatin accessibility, nucleosome positioning, and binding of HNF4α. Thus, the FoxA factors act continuously, guarding hepatic enhancer activity throughout adult life.

16.
Genes Dev ; 34(13-14): 973-988, 2020 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-32467224

RESUMO

Chromatin modifiers play critical roles in epidermal development, but the functions of histone deacetylases in this context are poorly understood. The class I HDAC, HDAC3, is of particular interest because it plays divergent roles in different tissues by partnering with tissue-specific transcription factors. We found that HDAC3 is expressed broadly in embryonic epidermis and is required for its orderly stepwise stratification. HDAC3 protein stability in vivo relies on NCoR and SMRT, which function redundantly in epidermal development. However, point mutations in the NCoR and SMRT deacetylase-activating domains, which are required for HDAC3's enzymatic function, permit normal stratification, indicating that HDAC3's roles in this context are largely independent of its histone deacetylase activity. HDAC3-bound sites are significantly enriched for predicted binding motifs for critical epidermal transcription factors including AP1, GRHL, and KLF family members. Our results suggest that among these, HDAC3 operates in conjunction with KLF4 to repress inappropriate expression of Tgm1, Krt16, and Aqp3 In parallel, HDAC3 suppresses expression of inflammatory cytokines through a Rela-dependent mechanism. These data identify HDAC3 as a hub coordinating multiple aspects of epidermal barrier acquisition.


Assuntos
Diferenciação Celular/genética , Células Epidérmicas/citologia , Epiderme/embriologia , Histona Desacetilases/genética , Histona Desacetilases/metabolismo , Animais , Embrião de Mamíferos , Deleção de Genes , Regulação da Expressão Gênica no Desenvolvimento , Genes Letais/genética , Fatores de Transcrição Kruppel-Like/genética , Camundongos , Camundongos Endogâmicos C57BL , Mutação , Correpressor 1 de Receptor Nuclear/genética , Correpressor 1 de Receptor Nuclear/metabolismo , Correpressor 2 de Receptor Nuclear/genética , Correpressor 2 de Receptor Nuclear/metabolismo , Domínios e Motivos de Interação entre Proteínas/genética , Fator de Transcrição RelA/genética , Fator de Transcrição RelA/metabolismo
17.
Immunity ; 52(2): 257-274.e11, 2020 02 18.
Artigo em Inglês | MEDLINE | ID: mdl-32049053

RESUMO

Genetics is a major determinant of susceptibility to autoimmune disorders. Here, we examined whether genome organization provides resilience or susceptibility to sequence variations, and how this would contribute to the molecular etiology of an autoimmune disease. We generated high-resolution maps of linear and 3D genome organization in thymocytes of NOD mice, a model of type 1 diabetes (T1D), and the diabetes-resistant C57BL/6 mice. Multi-enhancer interactions formed at genomic regions harboring genes with prominent roles in T cell development in both strains. However, diabetes risk-conferring loci coalesced enhancers and promoters in NOD, but not C57BL/6 thymocytes. 3D genome mapping of NODxC57BL/6 F1 thymocytes revealed that genomic misfolding in NOD mice is mediated in cis. Moreover, immune cells infiltrating the pancreas of humans with T1D exhibited increased expression of genes located on misfolded loci in mice. Thus, genetic variation leads to altered 3D chromatin architecture and associated changes in gene expression that may underlie autoimmune pathology.


Assuntos
Cromatina/metabolismo , Diabetes Mellitus Tipo 1/genética , Predisposição Genética para Doença/genética , Timócitos/patologia , Animais , Fator de Ligação a CCCTC/metabolismo , Mapeamento Cromossômico , Diabetes Mellitus Tipo 1/patologia , Epigênese Genética , Expressão Gênica , Loci Gênicos/genética , Variação Genética , Genoma/genética , Humanos , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Endogâmicos NOD , Pâncreas/patologia , Sequências Reguladoras de Ácido Nucleico
18.
Oncogene ; 39(6): 1302-1317, 2020 02.
Artigo em Inglês | MEDLINE | ID: mdl-31636388

RESUMO

Intratumoral heterogeneity in bladder cancer is a barrier to accurate molecular sub-classification and treatment efficacy. However, individual cellular and mechanistic contributions to tumor heterogeneity are controversial. We examined potential mechanisms of FOXA1 and PTEN inactivation in bladder cancer and their contribution to tumor heterogeneity. These analyses were complemented with inactivation of FOXA1 and PTEN in intermediate and luminal mouse urothelium. We show inactivation and reduced expression of FOXA1 and PTEN is prevalent in human disease, where PTEN and FOXA1 are downregulated by allelic loss and site-specific DNA hypermethylation, respectively. Conditional inactivation of both Foxa1 and Pten in intermediate/luminal cells in mice results in development of bladder cancer exhibiting squamous features as well as enhanced sensitivity to a bladder-specific carcinogen. In addition, FOXA1 is hypermethylated in basal bladder cancer cell lines, and this is reversed by treatment with DNA methyltransferase inhibitors. By integrating human correlative and in vivo studies, we define a critical role for PTEN loss and epigenetic silencing of FOXA1 in heterogeneous human disease and show genetic targeting of luminal/intermediate cells in mice drives squamous differentiation.


Assuntos
Carcinoma de Células Escamosas/patologia , Diferenciação Celular , Metilação de DNA , Fator 3-alfa Nuclear de Hepatócito/genética , Perda de Heterozigosidade , PTEN Fosfo-Hidrolase/genética , Neoplasias da Bexiga Urinária/patologia , Animais , Apoptose , Biomarcadores Tumorais , Carcinoma de Células Escamosas/genética , Carcinoma de Células Escamosas/metabolismo , Proliferação de Células , Feminino , Regulação Neoplásica da Expressão Gênica , Fator 3-alfa Nuclear de Hepatócito/metabolismo , Humanos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Neoplasias Musculares/genética , Neoplasias Musculares/metabolismo , Neoplasias Musculares/patologia , PTEN Fosfo-Hidrolase/metabolismo , Prognóstico , Células Tumorais Cultivadas , Neoplasias da Bexiga Urinária/genética , Neoplasias da Bexiga Urinária/metabolismo
19.
Cell Mol Gastroenterol Hepatol ; 9(1): 121-143, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-31629814

RESUMO

BACKGROUND & AIMS: The adult liver is the main detoxification organ and routinely is exposed to environmental insults but retains the ability to restore its mass and function upon tissue damage. However, extensive injury can lead to liver failure, and chronic injury causes fibrosis, cirrhosis, and hepatocellular carcinoma. Currently, the transcriptional regulation of organ repair in the adult liver is incompletely understood. METHODS: We isolated nuclei from quiescent as well as repopulating hepatocytes in a mouse model of hereditary tyrosinemia, which recapitulates the injury and repopulation seen in toxic liver injury in human beings. We then performed the assay for transposase accessible chromatin with high-throughput sequencing specifically in repopulating hepatocytes to identify differentially accessible chromatin regions and nucleosome positioning. In addition, we used motif analysis to predict differential transcription factor occupancy and validated the in silico results with chromatin immunoprecipitation followed by sequencing for hepatocyte nuclear factor 4α (HNF4α) and CCCTC-binding factor (CTCF). RESULTS: Chromatin accessibility in repopulating hepatocytes was increased in the regulatory regions of genes promoting proliferation and decreased in the regulatory regions of genes involved in metabolism. The epigenetic changes at promoters and liver enhancers correspond with the regulation of gene expression, with enhancers of many liver function genes showing a less accessible state during the regenerative process. Moreover, increased CTCF occupancy at promoters and decreased HNF4α binding at enhancers implicate these factors as key drivers of the transcriptomic changes in replicating hepatocytes that enable liver repopulation. CONCLUSIONS: Our analysis of hepatocyte-specific epigenomic changes during liver repopulation identified CTCF and HNF4α as key regulators of hepatocyte proliferation and regulation of metabolic programs. Thus, liver repopulation in the setting of toxic injury makes use of both general transcription factors (CTCF) for promoter activation, and reduced binding by a hepatocyte-enriched factor (HNF4α) to temporarily limit enhancer activity. All sequencing data in this study were deposited to the Gene Expression Omnibus database and can be downloaded with accession number GSE109466.

20.
Gastroenterology ; 158(4): 1044-1057.e17, 2020 03.
Artigo em Inglês | MEDLINE | ID: mdl-31759059

RESUMO

BACKGROUND & AIMS: Liver regeneration is impaired in mice with hepatocyte-specific deficiencies in microRNA (miRNA) processing, but it is not clear which miRNAs regulate this process. We developed a high-throughput screen to identify miRNAs that regulate hepatocyte repopulation after toxic liver injury using fumarylacetoacetate hydrolase-deficient mice. METHODS: We constructed plasmid pools encoding more than 30,000 tough decoy miRNA inhibitors (hairpin nucleic acids designed to specifically inhibit interactions between miRNAs and their targets) to target hepatocyte miRNAs in a pairwise manner. The plasmid libraries were delivered to hepatocytes in fumarylacetoacetate hydrolase-deficient mice at the time of liver injury via hydrodynamic tail-vein injection. Integrated transgene-containing transposons were quantified after liver repopulation via high-throughput sequencing. Changes in polysome-bound transcripts after miRNA inhibition were determined using translating ribosome affinity purification followed by high-throughput sequencing. RESULTS: Analyses of tough decoy abundance in hepatocyte genomic DNA and input plasmid pools identified several thousand miRNA inhibitors that were significantly depleted or increased after repopulation. We classified a subset of miRNA binding sites as those that have strong effects on liver repopulation, implicating the targeted hepatocyte miRNAs as regulators of this process. We then generated a high-content map of pairwise interactions between 171 miRNA-binding sites and identified synergistic and redundant effects. CONCLUSIONS: We developed a screen to identify miRNAs that regulate liver repopulation after injury in live mice.


Assuntos
Sequenciamento de Nucleotídeos em Larga Escala/métodos , Regeneração Hepática/genética , Fígado/lesões , MicroRNAs/análise , Animais , Mapeamento Cromossômico , Hepatócitos/fisiologia , Hidrolases/deficiência , Fígado/fisiopatologia , Camundongos , MicroRNAs/antagonistas & inibidores , Plasmídeos , Proteínas de Ligação a RNA/análise
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