RESUMO
There is pressing urgency to understand the pathogenesis of the severe acute respiratory syndrome coronavirus clade 2 (SARS-CoV-2), which causes the disease COVID-19. SARS-CoV-2 spike (S) protein binds angiotensin-converting enzyme 2 (ACE2), and in concert with host proteases, principally transmembrane serine protease 2 (TMPRSS2), promotes cellular entry. The cell subsets targeted by SARS-CoV-2 in host tissues and the factors that regulate ACE2 expression remain unknown. Here, we leverage human, non-human primate, and mouse single-cell RNA-sequencing (scRNA-seq) datasets across health and disease to uncover putative targets of SARS-CoV-2 among tissue-resident cell subsets. We identify ACE2 and TMPRSS2 co-expressing cells within lung type II pneumocytes, ileal absorptive enterocytes, and nasal goblet secretory cells. Strikingly, we discovered that ACE2 is a human interferon-stimulated gene (ISG) in vitro using airway epithelial cells and extend our findings to in vivo viral infections. Our data suggest that SARS-CoV-2 could exploit species-specific interferon-driven upregulation of ACE2, a tissue-protective mediator during lung injury, to enhance infection.
Assuntos
Células Epiteliais Alveolares/metabolismo , Enterócitos/metabolismo , Células Caliciformes/metabolismo , Interferon Tipo I/metabolismo , Mucosa Nasal/citologia , Peptidil Dipeptidase A/genética , Adolescente , Células Epiteliais Alveolares/imunologia , Enzima de Conversão de Angiotensina 2 , Animais , Betacoronavirus/fisiologia , COVID-19 , Linhagem Celular , Células Cultivadas , Criança , Infecções por Coronavirus/virologia , Enterócitos/imunologia , Células Caliciformes/imunologia , Infecções por HIV/imunologia , Humanos , Influenza Humana/imunologia , Interferon Tipo I/imunologia , Pulmão/citologia , Pulmão/patologia , Macaca mulatta , Camundongos , Mycobacterium tuberculosis , Mucosa Nasal/imunologia , Pandemias , Peptidil Dipeptidase A/metabolismo , Pneumonia Viral/virologia , Receptores Virais/genética , SARS-CoV-2 , Serina Endopeptidases/metabolismo , Análise de Célula Única , Tuberculose/imunologia , Regulação para CimaRESUMO
Genome-wide association studies (GWAS) have revealed risk alleles for ulcerative colitis (UC). To understand their cell type specificities and pathways of action, we generate an atlas of 366,650 cells from the colon mucosa of 18 UC patients and 12 healthy individuals, revealing 51 epithelial, stromal, and immune cell subsets, including BEST4+ enterocytes, microfold-like cells, and IL13RA2+IL11+ inflammatory fibroblasts, which we associate with resistance to anti-TNF treatment. Inflammatory fibroblasts, inflammatory monocytes, microfold-like cells, and T cells that co-express CD8 and IL-17 expand with disease, forming intercellular interaction hubs. Many UC risk genes are cell type specific and co-regulated within relatively few gene modules, suggesting convergence onto limited sets of cell types and pathways. Using this observation, we nominate and infer functions for specific risk genes across GWAS loci. Our work provides a framework for interrogating complex human diseases and mapping risk variants to cell types and pathways.
Assuntos
Colite Ulcerativa/patologia , Colo/metabolismo , Adulto , Idoso , Anticorpos Monoclonais/uso terapêutico , Bestrofinas/metabolismo , Antígenos CD8/metabolismo , Estudos de Casos e Controles , Colite Ulcerativa/tratamento farmacológico , Colite Ulcerativa/metabolismo , Colo/patologia , Enterócitos/citologia , Enterócitos/metabolismo , Feminino , Loci Gênicos , Estudo de Associação Genômica Ampla , Humanos , Interleucina-17/metabolismo , Masculino , Pessoa de Meia-Idade , Fatores de Risco , Linfócitos T/citologia , Linfócitos T/metabolismo , Trombospondinas/metabolismo , Fator de Necrose Tumoral alfa/imunologia , Fator de Necrose Tumoral alfa/metabolismo , Adulto JovemRESUMO
The intestinal epithelium is a highly structured tissue composed of repeating crypt-villus units. Enterocytes perform the diverse tasks of absorbing a wide range of nutrients while protecting the body from the harsh bacterium-rich environment. It is unknown whether these tasks are spatially zonated along the villus axis. Here, we extracted a large panel of landmark genes characterized by transcriptomics of laser capture microdissected villus segments and utilized it for single-cell spatial reconstruction, uncovering broad zonation of enterocyte function along the villus. We found that enterocytes at villus bottoms express an anti-bacterial gene program in a microbiome-dependent manner. They next shift to sequential expression of carbohydrates, peptides, and fat absorption machineries in distinct villus compartments. Finally, they induce a Cd73 immune-modulatory program at the villus tips. Our approach can be used to uncover zonation patterns in other organs when prior knowledge of landmark genes is lacking.
Assuntos
Enterócitos/metabolismo , Transcriptoma , Animais , Diferenciação Celular , Movimento Celular , Enterócitos/citologia , Enterócitos/fisiologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Análise de Célula ÚnicaRESUMO
Microbial functions in the host physiology are a result of the microbiota-host co-evolution. We show that cold exposure leads to marked shift of the microbiota composition, referred to as cold microbiota. Transplantation of the cold microbiota to germ-free mice is sufficient to increase insulin sensitivity of the host and enable tolerance to cold partly by promoting the white fat browning, leading to increased energy expenditure and fat loss. During prolonged cold, however, the body weight loss is attenuated, caused by adaptive mechanisms maximizing caloric uptake and increasing intestinal, villi, and microvilli lengths. This increased absorptive surface is transferable with the cold microbiota, leading to altered intestinal gene expression promoting tissue remodeling and suppression of apoptosis-the effect diminished by co-transplanting the most cold-downregulated strain Akkermansia muciniphila during the cold microbiota transfer. Our results demonstrate the microbiota as a key factor orchestrating the overall energy homeostasis during increased demand.
Assuntos
Metabolismo Energético , Microbioma Gastrointestinal , Trato Gastrointestinal/microbiologia , Trato Gastrointestinal/fisiologia , Homeostase , Tecido Adiposo Branco/metabolismo , Animais , Apoptose , Temperatura Baixa , Enterócitos/citologia , Enterócitos/metabolismo , Vida Livre de Germes , Resistência à Insulina , Absorção Intestinal , Camundongos , Verrucomicrobia/metabolismoRESUMO
Colorectal cancer is a leading cause of cancer-related deaths. Mutations in the innate immune sensor AIM2 are frequently identified in patients with colorectal cancer, but how AIM2 modulates colonic tumorigenesis is unknown. Here, we found that Aim2-deficient mice were hypersusceptible to colonic tumor development. Production of inflammasome-associated cytokines and other inflammatory mediators was largely intact in Aim2-deficient mice; however, intestinal stem cells were prone to uncontrolled proliferation. Aberrant Wnt signaling expanded a population of tumor-initiating stem cells in the absence of AIM2. Susceptibility of Aim2-deficient mice to colorectal tumorigenesis was enhanced by a dysbiotic gut microbiota, which was reduced by reciprocal exchange of gut microbiota with healthy wild-type mice. These findings uncover a synergy between a specific host genetic factor and gut microbiota in determining the susceptibility to colorectal cancer. Therapeutic modulation of AIM2 expression and microbiota has the potential to prevent colorectal cancer.
Assuntos
Proliferação de Células , Neoplasias Colorretais/metabolismo , Proteínas de Ligação a DNA/metabolismo , Células-Tronco/patologia , Animais , Azoximetano , Colite/induzido quimicamente , Neoplasias Colorretais/genética , Neoplasias Colorretais/imunologia , Neoplasias Colorretais/patologia , Sulfato de Dextrana , Enterócitos/patologia , Trato Gastrointestinal/microbiologia , Inflamassomos/metabolismo , Camundongos , Mutação , Células-Tronco/metabolismoRESUMO
Digested dietary fats are taken up by enterocytes where they are assembled into pre-chylomicrons in the endoplasmic reticulum followed by transport to the Golgi for maturation and subsequent secretion to the circulation1. The role of mitochondria in dietary lipid processing is unclear. Here we show that mitochondrial dysfunction in enterocytes inhibits chylomicron production and the transport of dietary lipids to peripheral organs. Mice with specific ablation of the mitochondrial aspartyl-tRNA synthetase DARS2 (ref. 2), the respiratory chain subunit SDHA3 or the assembly factor COX10 (ref. 4) in intestinal epithelial cells showed accumulation of large lipid droplets (LDs) in enterocytes of the proximal small intestine and failed to thrive. Feeding a fat-free diet suppressed the build-up of LDs in DARS2-deficient enterocytes, which shows that the accumulating lipids derive mostly from digested fat. Furthermore, metabolic tracing studies revealed an impaired transport of dietary lipids to peripheral organs in mice lacking DARS2 in intestinal epithelial cells. DARS2 deficiency caused a distinct lack of mature chylomicrons concomitant with a progressive dispersal of the Golgi apparatus in proximal enterocytes. This finding suggests that mitochondrial dysfunction results in impaired trafficking of chylomicrons from the endoplasmic reticulum to the Golgi, which in turn leads to storage of dietary lipids in large cytoplasmic LDs. Taken together, these results reveal a role for mitochondria in dietary lipid transport in enterocytes, which might be relevant for understanding the intestinal defects observed in patients with mitochondrial disorders5.
Assuntos
Gorduras na Dieta , Enterócitos , Metabolismo dos Lipídeos , Mitocôndrias , Animais , Camundongos , Aspartato-tRNA Ligase/metabolismo , Quilomícrons/metabolismo , Gorduras na Dieta/metabolismo , Complexo II de Transporte de Elétrons/metabolismo , Retículo Endoplasmático/metabolismo , Enterócitos/metabolismo , Enterócitos/patologia , Células Epiteliais/metabolismo , Complexo de Golgi/metabolismo , Intestinos , Gotículas Lipídicas/metabolismo , Mitocôndrias/metabolismo , Mitocôndrias/patologiaRESUMO
Transporting epithelial cells build apical microvilli to increase membrane surface area and enhance absorptive capacity. The intestinal brush border provides an elaborate example with tightly packed microvilli that function in nutrient absorption and host defense. Although the brush border is essential for physiological homeostasis, its assembly is poorly understood. We found that brush border assembly is driven by the formation of Ca(2+)-dependent adhesion links between adjacent microvilli. Intermicrovillar links are composed of protocadherin-24 and mucin-like protocadherin, which target to microvillar tips and interact to form a trans-heterophilic complex. The cytoplasmic domains of microvillar protocadherins interact with the scaffolding protein, harmonin, and myosin-7b, which promote localization to microvillar tips. Finally, a mouse model of Usher syndrome lacking harmonin exhibits microvillar protocadherin mislocalization and severe defects in brush border morphology. These data reveal an adhesion-based mechanism for brush border assembly and illuminate the basis of intestinal pathology in patients with Usher syndrome. PAPERFLICK:
Assuntos
Caderinas/metabolismo , Enterócitos/metabolismo , Microvilosidades/metabolismo , Animais , Células COS , Células CACO-2 , Proteínas Relacionadas a Caderinas , Cálcio/metabolismo , Proteínas de Transporte/genética , Proteínas de Transporte/metabolismo , Proteínas de Ciclo Celular , Chlorocebus aethiops , Proteínas do Citoesqueleto , Modelos Animais de Doenças , Enterócitos/citologia , Células HEK293 , Humanos , Camundongos , Camundongos Knockout , Microvilosidades/ultraestrutura , Miosinas/metabolismo , Síndromes de Usher/patologiaRESUMO
A fundamental and unresolved question in regenerative biology is how tissues return to homeostasis after injury. Answering this question is essential for understanding the aetiology of chronic disorders such as inflammatory bowel diseases and cancer1. We used the Drosophila midgut2 to investigate this and discovered that during regeneration a subpopulation of cholinergic3 neurons triggers Ca2+ currents among intestinal epithelial cells, the enterocytes, to promote return to homeostasis. We found that downregulation of the conserved cholinergic enzyme acetylcholinesterase4 in the gut epithelium enables acetylcholine from specific Egr5 (TNF in mammals)-sensing cholinergic neurons to activate nicotinic receptors in innervated enterocytes. This activation triggers high Ca2+, which spreads in the epithelium through Innexin2-Innexin7 gap junctions6, promoting enterocyte maturation followed by reduction of proliferation and inflammation. Disrupting this process causes chronic injury consisting of ion imbalance, Yki (YAP in humans) activation7, cell death and increase of inflammatory cytokines reminiscent of inflammatory bowel diseases8. Altogether, the conserved cholinergic pathway facilitates epithelial Ca2+ currents that heal the intestinal epithelium. Our findings demonstrate nerve- and bioelectric9-dependent intestinal regeneration and advance our current understanding of how a tissue returns to homeostasis after injury.
Assuntos
Sinalização do Cálcio , Cálcio , Neurônios Colinérgicos , Drosophila melanogaster , Enterócitos , Intestinos , Animais , Humanos , Acetilcolina/metabolismo , Acetilcolinesterase/metabolismo , Cálcio/metabolismo , Neurônios Colinérgicos/metabolismo , Drosophila melanogaster/enzimologia , Drosophila melanogaster/metabolismo , Enterócitos/metabolismo , Homeostase , Inflamação/enzimologia , Inflamação/metabolismo , Doenças Inflamatórias Intestinais/metabolismo , Intestinos/citologia , Intestinos/metabolismo , Receptores Nicotínicos/metabolismo , Modelos Animais de DoençasRESUMO
The gut microbiota and their metabolites are closely linked to obesity-related diseases, such as type 2 diabetes, but their causal relationship and underlying mechanisms remain largely elusive. Here, we found that dysbiosis-induced tyramine (TA) suppresses high-fat diet (HFD)-mediated insulin resistance in both Drosophila and mice. In Drosophila, HFD increases cytosolic Ca2+ signaling in enterocytes, which, in turn, suppresses intestinal lipid levels. 16 S rRNA sequencing and metabolomics revealed that HFD leads to increased prevalence of tyrosine decarboxylase (Tdc)-expressing bacteria and resulting tyramine production. Tyramine acts on the tyramine receptor, TyrR1, to promote cytosolic Ca2+ signaling and activation of the CRTC-CREB complex to transcriptionally suppress dietary lipid digestion and lipogenesis in enterocytes, while promoting mitochondrial biogenesis. Furthermore, the tyramine-induced cytosolic Ca2+ signaling is sufficient to suppress HFD-induced obesity and insulin resistance in Drosophila. In mice, tyramine intake also improves glucose tolerance and insulin sensitivity under HFD. These results indicate that dysbiosis-induced tyramine suppresses insulin resistance in both flies and mice under HFD, suggesting a potential therapeutic strategy for related metabolic disorders, such as diabetes.
Assuntos
Sinalização do Cálcio , Dieta Hiperlipídica , Microbioma Gastrointestinal , Resistência à Insulina , Tiramina , Animais , Tiramina/metabolismo , Tiramina/farmacologia , Microbioma Gastrointestinal/efeitos dos fármacos , Dieta Hiperlipídica/efeitos adversos , Camundongos , Sinalização do Cálcio/efeitos dos fármacos , Obesidade/metabolismo , Obesidade/microbiologia , Obesidade/etiologia , Masculino , Drosophila/metabolismo , Disbiose/metabolismo , Disbiose/microbiologia , Camundongos Endogâmicos C57BL , Drosophila melanogaster/microbiologia , Drosophila melanogaster/metabolismo , Enterócitos/metabolismo , Enterócitos/efeitos dos fármacosRESUMO
It is assumed that collateral damage from the immune system drives intestinal epithelial cell (IEC) expulsion during enteric infections. In this issue of Immunity, Zhai et al. (2018) describe how Drosophila's canonical immune deficiency (Imd) pathway programs IEC delamination in the gut.
Assuntos
Enterócitos , NF-kappa B , Animais , Antibacterianos , Infecções Bacterianas , Células EpiteliaisRESUMO
Intestinal infection triggers potent immune responses to combat pathogens and concomitantly drives epithelial renewal to maintain barrier integrity. Current models propose that epithelial renewal is primarily driven by damage caused by reactive oxygen species (ROS). Here we found that in Drosophila, the Imd-NF-κB pathway controlled enterocyte (EC) shedding upon infection, via a mechanism independent of ROS-associated apoptosis. Mechanistically, the Imd pathway synergized with JNK signaling to induce epithelial cell shedding specifically in the context of bacterial infection, requiring also the reduced expression of the transcription factor GATAe. Furthermore, cell-specific NF-κB responses enabled simultaneous production of antimicrobial peptides (AMPs) and epithelial shedding in different EC populations. Thus, the Imd-NF-κB pathway is central to the intestinal antibacterial response by mediating both AMP production and the maintenance of barrier integrity. Considering the similarities between Drosophila Imd signaling and mammalian TNFR pathway, our findings suggest the existence of an evolutionarily conserved genetic program in immunity-induced epithelial shedding.
Assuntos
Peptídeos Catiônicos Antimicrobianos/imunologia , Bactérias/imunologia , Infecções Bacterianas/imunologia , Proteínas de Drosophila/imunologia , Células Epiteliais/imunologia , NF-kappa B/imunologia , Animais , Animais Geneticamente Modificados , Peptídeos Catiônicos Antimicrobianos/metabolismo , Bactérias/crescimento & desenvolvimento , Infecções Bacterianas/metabolismo , Infecções Bacterianas/microbiologia , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/imunologia , Drosophila melanogaster/metabolismo , Drosophila melanogaster/microbiologia , Enterócitos/imunologia , Enterócitos/metabolismo , Enterócitos/microbiologia , Células Epiteliais/metabolismo , Células Epiteliais/microbiologia , Fatores de Transcrição GATA/genética , Fatores de Transcrição GATA/imunologia , Fatores de Transcrição GATA/metabolismo , Regulação da Expressão Gênica/imunologia , Mucosa Intestinal/citologia , NF-kappa B/metabolismo , Transdução de Sinais/imunologiaRESUMO
A balanced intake of macronutrients-protein, carbohydrate and fat-is essential for the well-being of organisms. An adequate calorific intake but with insufficient protein consumption can lead to several ailments, including kwashiorkor1. Taste receptors (T1R1-T1R3)2 can detect amino acids in the environment, and cellular sensors (Gcn2 and Tor)3 monitor the levels of amino acids in the cell. When deprived of dietary protein, animals select a food source that contains a greater proportion of protein or essential amino acids (EAAs)4. This suggests that food selection is geared towards achieving the target amount of a particular macronutrient with assistance of the EAA-specific hunger-driven response, which is poorly understood. Here we show in Drosophila that a microbiome-gut-brain axis detects a deficit of EAAs and stimulates a compensatory appetite for EAAs. We found that the neuropeptide CNMamide (CNMa)5 was highly induced in enterocytes of the anterior midgut during protein deprivation. Silencing of the CNMa-CNMa receptor axis blocked the EAA-specific hunger-driven response in deprived flies. Furthermore, gnotobiotic flies bearing an EAA-producing symbiotic microbiome exhibited a reduced appetite for EAAs. By contrast, gnotobiotic flies with a mutant microbiome that did not produce leucine or other EAAs showed higher expression of CNMa and a greater compensatory appetite for EAAs. We propose that gut enterocytes sense the levels of diet- and microbiome-derived EAAs and communicate the EAA-deprived condition to the brain through CNMa.
Assuntos
Aminoácidos Essenciais/administração & dosagem , Eixo Encéfalo-Intestino , Drosophila/fisiologia , Preferências Alimentares , Microbioma Gastrointestinal , Aminoácidos Essenciais/deficiência , Fenômenos Fisiológicos da Nutrição Animal , Animais , Animais Geneticamente Modificados , Apetite , Enterócitos , Feminino , Vida Livre de Germes , Fome , Leucina , SimbioseRESUMO
The production of IFN-γ is crucial for control of multiple enteric infections, but its impact on intestinal epithelial cells (IEC) is not well understood. Cryptosporidium parasites exclusively infect epithelial cells and the ability of interferons to activate the transcription factor STAT1 in IEC is required for parasite clearance. Here, the use of single cell RNA sequencing to profile IEC during infection revealed an increased proportion of mid-villus enterocytes during infection and induction of IFN-γ-dependent gene signatures that was comparable between uninfected and infected cells. These analyses were complemented by in vivo studies, which demonstrated that IEC expression of the IFN-γ receptor was required for parasite control. Unexpectedly, treatment of Ifng-/- mice with IFN-γ showed the IEC response to this cytokine correlates with a delayed reduction in parasite burden but did not affect parasite development. These data sets provide insight into the impact of IFN-γ on IEC and suggest a model in which IFN-γ signalling to uninfected enterocytes is important for control of Cryptosporidium.
Assuntos
Criptosporidiose , Interferon gama , Mucosa Intestinal , Camundongos Knockout , Animais , Interferon gama/metabolismo , Interferon gama/imunologia , Criptosporidiose/imunologia , Criptosporidiose/parasitologia , Camundongos , Mucosa Intestinal/parasitologia , Mucosa Intestinal/metabolismo , Mucosa Intestinal/imunologia , Cryptosporidium , Células Epiteliais/parasitologia , Células Epiteliais/metabolismo , Células Epiteliais/imunologia , Enterócitos/parasitologia , Enterócitos/metabolismo , Enterócitos/imunologia , Camundongos Endogâmicos C57BL , Receptor de Interferon gama , Fator de Transcrição STAT1/metabolismo , Receptores de Interferon/metabolismo , Receptores de Interferon/genética , Transdução de SinaisRESUMO
Within the gut, Salmonella-infected enterocytes are expelled into the lumen, limiting pathogen replication. In this issue of Immunity, Rauch et al. (2017) expand our understanding of this cell-intrinsic response by characterizing the genetic determinants that control the expulsion and death of epithelial cells.
Assuntos
Infecções por Salmonella/imunologia , Salmonella/imunologia , Enterócitos/imunologia , Células Epiteliais , ImunidadeRESUMO
In cells, organs and whole organisms, nutrient sensing is key to maintaining homeostasis and adapting to a fluctuating environment1. In many animals, nutrient sensors are found within the enteroendocrine cells of the digestive system; however, less is known about nutrient sensing in their cellular siblings, the absorptive enterocytes1. Here we use a genetic screen in Drosophila melanogaster to identify Hodor, an ionotropic receptor in enterocytes that sustains larval development, particularly in nutrient-scarce conditions. Experiments in Xenopus oocytes and flies indicate that Hodor is a pH-sensitive, zinc-gated chloride channel that mediates a previously unrecognized dietary preference for zinc. Hodor controls systemic growth from a subset of enterocytes-interstitial cells-by promoting food intake and insulin/IGF signalling. Although Hodor sustains gut luminal acidity and restrains microbial loads, its effect on systemic growth results from the modulation of Tor signalling and lysosomal homeostasis within interstitial cells. Hodor-like genes are insect-specific, and may represent targets for the control of disease vectors. Indeed, CRISPR-Cas9 genome editing revealed that the single hodor orthologue in Anopheles gambiae is an essential gene. Our findings highlight the need to consider the instructive contributions of metals-and, more generally, micronutrients-to energy homeostasis.
Assuntos
Canais de Cloreto/metabolismo , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/crescimento & desenvolvimento , Drosophila melanogaster/metabolismo , Ingestão de Alimentos/fisiologia , Intestinos/fisiologia , Zinco/metabolismo , Animais , Drosophila melanogaster/genética , Enterócitos/metabolismo , Feminino , Preferências Alimentares , Homeostase , Insetos Vetores , Insulina/metabolismo , Ativação do Canal Iônico , Larva/genética , Larva/crescimento & desenvolvimento , Larva/metabolismo , Lisossomos/metabolismo , Masculino , Oócitos/metabolismo , Receptores Proteína Tirosina Quinases/metabolismo , Transdução de Sinais , XenopusRESUMO
Metformin, the world's most prescribed anti-diabetic drug, is also effective in preventing type 2 diabetes in people at high risk1,2. More than 60% of this effect is attributable to the ability of metformin to lower body weight in a sustained manner3. The molecular mechanisms by which metformin lowers body weight are unknown. Here we show-in two independent randomized controlled clinical trials-that metformin increases circulating levels of the peptide hormone growth/differentiation factor 15 (GDF15), which has been shown to reduce food intake and lower body weight through a brain-stem-restricted receptor. In wild-type mice, oral metformin increased circulating GDF15, with GDF15 expression increasing predominantly in the distal intestine and the kidney. Metformin prevented weight gain in response to a high-fat diet in wild-type mice but not in mice lacking GDF15 or its receptor GDNF family receptor α-like (GFRAL). In obese mice on a high-fat diet, the effects of metformin to reduce body weight were reversed by a GFRAL-antagonist antibody. Metformin had effects on both energy intake and energy expenditure that were dependent on GDF15, but retained its ability to lower circulating glucose levels in the absence of GDF15 activity. In summary, metformin elevates circulating levels of GDF15, which is necessary to obtain its beneficial effects on energy balance and body weight, major contributors to its action as a chemopreventive agent.
Assuntos
Peso Corporal/efeitos dos fármacos , Metabolismo Energético/efeitos dos fármacos , Fator 15 de Diferenciação de Crescimento/metabolismo , Metformina/farmacologia , Administração Oral , Adulto , Idoso , Animais , Glicemia/análise , Glicemia/metabolismo , Dieta Hiperlipídica , Método Duplo-Cego , Ingestão de Energia/efeitos dos fármacos , Enterócitos/citologia , Enterócitos/efeitos dos fármacos , Feminino , Receptores de Fator Neurotrófico Derivado de Linhagem de Célula Glial/antagonistas & inibidores , Receptores de Fator Neurotrófico Derivado de Linhagem de Célula Glial/deficiência , Receptores de Fator Neurotrófico Derivado de Linhagem de Célula Glial/genética , Fator 15 de Diferenciação de Crescimento/sangue , Fator 15 de Diferenciação de Crescimento/deficiência , Fator 15 de Diferenciação de Crescimento/genética , Homeostase/efeitos dos fármacos , Humanos , Intestinos/citologia , Intestinos/efeitos dos fármacos , Masculino , Metformina/administração & dosagem , Camundongos , Camundongos Obesos , Pessoa de Meia-Idade , Redução de Peso/efeitos dos fármacosRESUMO
The development of intestinal organoids from single adult intestinal stem cells in vitro recapitulates the regenerative capacity of the intestinal epithelium1,2. Here we unravel the mechanisms that orchestrate both organoid formation and the regeneration of intestinal tissue, using an image-based screen to assay an annotated library of compounds. We generate multivariate feature profiles for hundreds of thousands of organoids to quantitatively describe their phenotypic landscape. We then use these phenotypic fingerprints to infer regulatory genetic interactions, establishing a new approach to the mapping of genetic interactions in an emergent system. This allows us to identify genes that regulate cell-fate transitions and maintain the balance between regeneration and homeostasis, unravelling previously unknown roles for several pathways, among them retinoic acid signalling. We then characterize a crucial role for retinoic acid nuclear receptors in controlling exit from the regenerative state and driving enterocyte differentiation. By combining quantitative imaging with RNA sequencing, we show the role of endogenous retinoic acid metabolism in initiating transcriptional programs that guide the cell-fate transitions of intestinal epithelium, and we identify an inhibitor of the retinoid X receptor that improves intestinal regeneration in vivo.
Assuntos
Organoides/citologia , Organoides/fisiologia , Fenótipo , Regeneração/fisiologia , Animais , Diferenciação Celular/efeitos dos fármacos , Diferenciação Celular/genética , Enterócitos/citologia , Enterócitos/efeitos dos fármacos , Homeostase/efeitos dos fármacos , Mucosa Intestinal/efeitos dos fármacos , Mucosa Intestinal/metabolismo , Intestinos/citologia , Intestinos/efeitos dos fármacos , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Organoides/efeitos dos fármacos , Organoides/metabolismo , Receptores do Ácido Retinoico/antagonistas & inibidores , Receptores do Ácido Retinoico/metabolismo , Regeneração/efeitos dos fármacos , Análise de Sequência de RNA , Transdução de Sinais/efeitos dos fármacos , Transcrição Gênica/efeitos dos fármacos , Tretinoína/metabolismo , Vitamina A/farmacologiaRESUMO
DNA methylation functions as a repressive epigenetic mark that can be reversed by the Ten-eleven translocation (TET) family of DNA dioxygenases that sequentially oxidize 5-methylcytosine into 5-hydroxymethylcytosine (5hmC), 5-formylcytosine (5fC), and 5-carboxylcytosine (5caC). Both 5fC and 5caC can be excised by DNA base-excision repair factors leading to unmodified cytosines. TET enzymes were recently implicated as potential risk factors for inflammatory bowel disease (IBD), but the contribution of TET-mediated DNA oxidation to intestinal homeostasis and response to environmental stressors are unknown. Here, we show prominent roles of TET3 in regulating mouse intestinal epithelial differentiation and response to luminal stressors. Compared with wild-type littermates, mice with intestinal epithelial cell-specific ablation of Tet3 (Tet3ΔIEC) demonstrated a decreased transcriptome involved in innate immune response, Paneth cell differentiation, and epithelial regeneration. Tet3IEC mice exhibited an elevated susceptibility to enteric pathogen infection that is correlated with a decreased epithelial 5hmC abundance. Infection of human enterocytes or mice with the pathogenic bacteria acutely increased 5hmC abundance. Genome-wide 5hmC profiling revealed a shift of genomic enrichment of 5hmC toward genes involved in activating Notch, Wnt, and autophagy pathways. Furthermore, chemical stressor dextran sulfate sodium (DSS) represses epithelial 5hmC abundance in a temporal fashion, and Tet3IEC mice exhibited increased susceptibility to DSS experimental colitis with reduced regenerative capacity. TET3 is a critical regulator of gut epithelial DNA methylome and transcriptome, especially in response to luminal stressors, for the maintenance of tissue homeostasis.
Assuntos
Colite , Dioxigenases , Animais , Humanos , Camundongos , DNA , Enterócitos , Oxirredução , Celulas de PanethRESUMO
As one of the most important causative agents of severe gastroenteritis in children, piglets, and other young animals, species A rotaviruses have adversely impacted both human health and the global swine industry. Vaccines against rotaviruses (RVs) are insufficiently effective, and no specific treatment is available. To understand the relationships between porcine RV (PoRV) infection and enterocytes in terms of the cellular lipid metabolism, we performed an untargeted liquid chromatography mass spectrometry (LC-MS) lipidomics analysis of PoRV-infected IPEC-J2 cells. Herein, a total of 451 lipids (263 upregulated lipids and 188 downregulated lipids), spanning sphingolipid, glycerolipid, and glycerophospholipids, were significantly altered compared with the mock-infected group. Interestingly, almost all the ceramides among these lipids were upregulated during PoRV infection. LC-MS analysis was used to validated the lipidomics data and demonstrated that PoRV replication increased the levels of long-chain ceramides (C16-ceramide, C18-ceramide, and C24-ceramide) in cells. Furthermore, we found that these long-chain ceramides markedly inhibited PoRV infection and that their antiviral actions were exerted in the replication stage of PoRV infection. Moreover, downregulation of endogenous ceramides with the ceramide metabolic inhibitors enhanced PoRV propagation. Increasing the levels of ceramides by the addition of C6-ceramide strikingly suppressed the replication of diverse RV strains. We further found that the treatment with an apoptotic inhibitor could reverse the antiviral activity of ceramide against PoRV replication, demonstrating that ceramide restricted RV infection by inducing apoptosis. Altogether, this study revealed that ceramides played an antiviral role against RV infection, providing potential approaches for the development of antiviral therapies.IMPORTANCERotaviruses (RVs) are among the most important zoonosis viruses, which mainly infected enterocytes of the intestinal epithelium causing diarrhea in children and the young of many mammalian and avian species. Lipids play an essential role in viral infection. A comprehensive understanding of the interaction between RV and lipid metabolism in the enterocytes will be helpful to control RV infection. Here, we mapped changes in enterocyte lipids following porcine RV (PoRV) infection using an untargeted lipidomics approach. We found that PoRV infection altered the metabolism of various lipid species, especially ceramides (derivatives of the sphingosine). We further demonstrated that PoRV infection increased the accumulation of ceramides and that ceramides exerted antiviral effects on RV replication by inducing apoptosis. Our findings fill a gap in understanding the alterations of lipid metabolism in RV-infected enterocytes and highlight the antiviral effects of ceramides on RV infection, suggesting potential approaches to control RV infection.
Assuntos
Ceramidas , Infecções por Rotavirus , Rotavirus , Animais , Ceramidas/metabolismo , Metabolismo dos Lipídeos , Lipidômica , Rotavirus/fisiologia , Suínos , Enterócitos/metabolismo , Enterócitos/virologia , Infecções por Rotavirus/metabolismo , Linhagem CelularRESUMO
Intestinal failure-associated liver disease (IFALD) is a serious complication of long-term parenteral nutrition in patients with short bowel syndrome (SBS), and is the main cause of death in SBS patients. Prevention of IFALD is one of the major challenges in the treatment of SBS. Impairment of intestinal barrier function is a key factor in triggering IFALD, therefore promoting intestinal repair is particularly important. Intestinal repair mainly relies on the function of intestinal stem cells (ISC), which require robust mitochondrial fatty acid oxidation (FAO) for self-renewal. Herein, we report that aberrant LGR5+ ISC function in IFALD may be attributed to impaired farnesoid X receptor (FXR) signaling, a transcriptional factor activated by steroids and bile acids. In both surgical biopsies and patient-derived organoids (PDOs), SBS patients with IFALD represented lower population of LGR5+ cells and decreased FXR expression. Moreover, treatment with T-ßMCA in PDOs (an antagonist for FXR) dose-dependently reduced the population of LGR5+ cells and the proliferation rate of enterocytes, concomitant with decreased key genes involved in FAO including CPT1a. Interestingly, however, treatment with Tropifexor in PDOs (an agonist for FXR) only enhanced FAO capacity, without improvement in ISC function and enterocyte proliferation. In conclusion, these findings suggested that impaired FXR may accelerate the depletion of LGR5 + ISC population through disrupted FAO processes, which may serve as a new potential target of preventive interventions against IFALD for SBS patients.