RESUMO
Ferroptosis is a form of cell death that is induced by iron-mediated accumulation of lipid peroxidation. The involvement of ferroptosis in different pathophysiological conditions has offered new perspectives on potential therapeutic interventions. Natural products, which are widely recognized for their significance in drug discovery and repurposing, have shown great promise in regulating ferroptosis by targeting various ferroptosis players. In this review, we discuss the regulatory mechanisms of ferroptosis and its implications in different pathological conditions. We dissect the interactions between natural products and ferroptosis in cancer, ischemia/reperfusion, neurodegenerative diseases, acute kidney injury, liver injury, and cardiomyopathy, with an emphasis on the relevance of ferroptosis players to disease targetability.
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BACKGROUND: The peroxisome is a dynamic organelle with variety in number, size, shape, and activity in different cell types and physiological states. Recent studies have implicated peroxisomal homeostasis in ferroptosis susceptibility. Here, we developed a U-2OS cell line with a fluorescent peroxisomal tag and screened a target-selective chemical library through high-content imaging analysis. METHODS: U-2OS cells stably expressing the mOrange2-Peroxisomes2 tag were generated to screen a target-selective inhibitor library. The nuclear DNA was counterstained with Hoechst 33342 for cell cycle analysis. Cellular images were recorded and quantitatively analyzed through a high-content imaging platform. The effect of selected compounds on ferroptosis induction was analyzed in combination with ferroptosis inducers (RSL3 and erastin). Flow cytometry analysis was conducted to assess the level of reactive oxygen species (ROS) and cell death events. RESULTS: Through the quantification of DNA content and peroxisomal signals in single cells, we demonstrated that peroxisomal abundance was closely linked with cell cycle progression and that peroxisomal biogenesis mainly occurred in the G1/S phase. We further identified compounds that positively and negatively regulated peroxisomal abundance without significantly affecting the cell cycle distribution. Some compounds promoted peroxisomal signals by inducing oxidative stress, while others regulated peroxisomal abundance independent of redox status. Importantly, compounds with peroxisome-enhancing activity potentiated ferroptosis induction. CONCLUSIONS: Our findings pinpoint novel cellular targets that might be involved in peroxisome homeostasis and indicate that compounds promoting peroxisomal abundance could be jointly applied with ferroptosis inducers to potentiate anticancer effect.
Assuntos
Ferroptose , Peroxissomos , Peroxissomos/metabolismo , Linhagem Celular , Estresse Oxidativo , Espécies Reativas de Oxigênio/metabolismo , DNA/metabolismoRESUMO
Ferroptosis has been conceptualized as a novel cell death modality distinct from apoptosis, necroptosis, pyroptosis and autophagic cell death. The sensitivity of cellular ferroptosis is regulated at multiple layers, including polyunsaturated fatty acid metabolism, glutathione-GPX4 axis, iron homeostasis, mitochondria and other parallel pathways. In addition, microRNAs (miRNAs) have been implicated in modulating ferroptosis susceptibility through targeting different players involved in the execution or avoidance of ferroptosis. A growing body of evidence pinpoints the deregulation of miRNA-regulated ferroptosis as a critical factor in the development and progression of various pathophysiological conditions related to iron overload. The revelation of mechanisms of miRNA-dependent ferroptosis provides novel insights into the etiology of diseases and offers opportunities for therapeutic intervention. In this review, we discuss the interplay of emerging miRNA regulators and ferroptosis players under different pathological conditions, such as cancers, ischemia/reperfusion, neurodegenerative diseases, acute kidney injury and cardiomyopathy. We emphasize on the relevance of miRNA-regulated ferroptosis to disease progression and the targetability for therapeutic interventions.
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Injúria Renal Aguda , Ferroptose , Sobrecarga de Ferro , MicroRNAs , Humanos , Apoptose , Ferroptose/genética , Sobrecarga de Ferro/genética , MicroRNAs/genéticaRESUMO
Macrophages are highly plastic in different tissues and can differentiate into functional subpopulations under different stimuli. Tumor-associated macrophages (TAMs) are one of the most important innate immune cells implicated in the establishment of an immunosuppressive tumor microenvironment (TME). Recent evidence pinpoints the critical role of metabolic reprogramming in dictating pro-tumorigenic functions of TAMs. Both tumor cells and macrophages undergo metabolic reprogramming to meet energy demands in the TME. Understanding the metabolic rewiring in TAMs can shed light on immune escape mechanisms and provide insights into repolarizing TAMs towards anti-tumorigenic function. Here, we discuss how metabolism impinges on the functional divergence of macrophages and its relevance to macrophage polarization in the TME.
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Macrófagos , Macrófagos Associados a Tumor , Humanos , Carcinogênese , Imunossupressores , Ativação de Macrófagos , Microambiente TumoralRESUMO
Exposure of lipopolysaccharide triggers macrophage pro-inflammatory polarization accompanied by metabolic reprogramming, characterized by elevated aerobic glycolysis and a broken tricarboxylic acid cycle. However, in contrast to lipopolysaccharide, CD40 signal is able to drive pro-inflammatory and anti-tumorigenic polarization by some yet undefined metabolic programming. Here we show that CD40 activation triggers fatty acid oxidation (FAO) and glutamine metabolism to promote ATP citrate lyase-dependent epigenetic reprogramming of pro-inflammatory genes and anti-tumorigenic phenotypes in macrophages. Mechanistically, glutamine usage reinforces FAO-induced pro-inflammatory and anti-tumorigenic activation by fine-tuning the NAD+/NADH ratio via glutamine-to-lactate conversion. Genetic ablation of important metabolic enzymes involved in CD40-mediated metabolic reprogramming abolishes agonistic anti-CD40-induced antitumor responses and reeducation of tumor-associated macrophages. Together these data show that metabolic reprogramming, which includes FAO and glutamine metabolism, controls the activation of pro-inflammatory and anti-tumorigenic polarization, and highlight a therapeutic potential of metabolic preconditioning of tumor-associated macrophages before agonistic anti-CD40 treatments.
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Ácidos Graxos , Glutamina , Glutamina/metabolismo , Ácidos Graxos/metabolismo , Lipopolissacarídeos/metabolismo , Glicólise , Macrófagos/metabolismo , Ativação de MacrófagosRESUMO
Oncogene-induced hyper-proliferation in cancer cells is accompanied by the onset of different stresses, including DNA-replication stress, metabolic stress and oxidative stress. Excessive accumulation of reactive oxygen species (ROS) plays a pivotal and contradictory role in tumor progression. ROS dictates a multitude of cell signaling pathways to facilitate the malignant transformation of tumor cells. In the meantime, oxidative burden in tumor cells mandates reinforcing antioxidant capacity to mitigate detrimental damages. The addiction to oxidative stress and increased iron demands in cancer cells also impinges on the sensitivity of ferroptosis. Targeting redox homeostasis and ferroptosis to overcome drug resistance in cancer treatment has become an attractive research topic. However, the roles of oncogenic signaling in redox regulation and ferroptosis have not been comprehensively discussed. In this review, we summarize current knowledge regarding the interplay between redox regulation and ferroptosis in the context of cancer biology. We emphasize the implication of oncogenic signaling in redox homeostasis and ferroptosis regulation. We also provide an overview of strategies targeting oxidative stress and ferroptosis in cancer treatment.
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Ferroptose , Neoplasias , Humanos , Espécies Reativas de Oxigênio/metabolismo , Estresse Oxidativo , Neoplasias/patologia , Transdução de SinaisRESUMO
Chronic inflammation triggers compensatory immunosuppression to stop inflammation and minimize tissue damage. Studies have demonstrated that endoplasmic reticulum (ER) stress augments the suppressive phenotypes of immune cells; however, the molecular mechanisms underpinning this process and how it links to the metabolic reprogramming of immunosuppressive macrophages remain elusive. In the present study, we report that the helper T cell 2 cytokine interleukin-4 and the tumor microenvironment increase the activity of a protein kinase RNA-like ER kinase (PERK)-signaling cascade in macrophages and promote immunosuppressive M2 activation and proliferation. Loss of PERK signaling impeded mitochondrial respiration and lipid oxidation critical for M2 macrophages. PERK activation mediated the upregulation of phosphoserine aminotransferase 1 (PSAT1) and serine biosynthesis via the downstream transcription factor ATF-4. Increased serine biosynthesis resulted in enhanced mitochondrial function and α-ketoglutarate production required for JMJD3-dependent epigenetic modification. Inhibition of PERK suppressed macrophage immunosuppressive activity and could enhance the efficacy of immune checkpoint programmed cell death protein 1 inhibition in melanoma. Our findings delineate a previously undescribed connection between PERK signaling and PSAT1-mediated serine metabolism critical for promoting immunosuppressive function in M2 macrophages.
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Estresse do Retículo Endoplasmático , eIF-2 Quinase , Estresse do Retículo Endoplasmático/genética , Macrófagos/metabolismo , Transdução de Sinais , Resposta a Proteínas não Dobradas , eIF-2 Quinase/genética , eIF-2 Quinase/metabolismoRESUMO
The metabolic challenges present in tumors attenuate the metabolic fitness and antitumor activity of tumor-infiltrating T lymphocytes (TILs). However, it remains unclear whether persistent metabolic insufficiency can imprint permanent T cell dysfunction. We found that TILs accumulated depolarized mitochondria as a result of decreased mitophagy activity and displayed functional, transcriptomic and epigenetic characteristics of terminally exhausted T cells. Mechanistically, reduced mitochondrial fitness in TILs was induced by the coordination of T cell receptor stimulation, microenvironmental stressors and PD-1 signaling. Enforced accumulation of depolarized mitochondria with pharmacological inhibitors induced epigenetic reprogramming toward terminal exhaustion, indicating that mitochondrial deregulation caused T cell exhaustion. Furthermore, supplementation with nicotinamide riboside enhanced T cell mitochondrial fitness and improved responsiveness to anti-PD-1 treatment. Together, our results reveal insights into how mitochondrial dynamics and quality orchestrate T cell antitumor responses and commitment to the exhaustion program.
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Linfócitos T CD8-Positivos/imunologia , Linfócitos T CD8-Positivos/metabolismo , Contagem de Linfócitos , Linfócitos do Interstício Tumoral/imunologia , Linfócitos do Interstício Tumoral/metabolismo , Dinâmica Mitocondrial/imunologia , Biomarcadores , Epigênese Genética , Epigenômica , Humanos , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/imunologia , Mitocôndrias/metabolismo , Mitocôndrias/ultraestrutura , Mitofagia , Neoplasias/imunologia , Neoplasias/metabolismo , Neoplasias/patologia , Neoplasias/terapia , Niacinamida/farmacologia , Receptor de Morte Celular Programada 1/metabolismo , Receptores de Antígenos de Linfócitos T/metabolismo , Transdução de Sinais , Estresse Fisiológico , Subpopulações de Linfócitos T/imunologia , Subpopulações de Linfócitos T/metabolismoRESUMO
The activation of innate immunity by viral nucleic acids present in the cytoplasm plays an essential role in controlling viral infection in both immune and non-immune cells. The dsDNA and dsRNA viral mimics can stimulate the cytosolic nucleic acids sensors and activate the antiviral innate immunity. In this study, taking advantage of dsDNA and dsRNA viral mimics, we investigated the global transcriptome changes after the antiviral immunity activation in mouse embryonic fibroblasts. Results from our data identified a positive feedback up-regulation of sensors (e.g., Tlr2, Tlr3, Ddx58, cGAS), transducers (e.g., Traf2, Tbk1) and transcription factors (e.g., Irf7, Jun, Stat1, Stat2) in multiple pathways involved in detecting viral or microbial infections upon viral mimic stimulation. A group of genes involved in DNA damage response and DNA repair such as Parp9, Dtx3l, Rad52 were also up-regulated, implying the involvement of these genes in antiviral immunity. Molecular function analysis further showed that groups of helicase genes (e.g., Dhx58, Helz2), nuclease genes (e.g., Dnase1l3, Rsph10b), methyltransferase genes (e.g., histone methyltransferase Prdm9, Setdb2; RNA methyltransferase Mettl3, Mttl14), and protein ubiquitin-ligase genes (e.g., Trim genes and Rnf genes) were up-regulated upon antiviral immunity activation. In contrast, viral mimic stimulation down-regulated genes involved in a broad range of general biological processes (e.g., cell division, metabolism), cellular components (e.g., mitochondria and ribosome), and molecular functions (e.g., cell-cell adhesion, microtubule binding). In summary, our study provides valuable information about the global transcriptome changes upon antiviral immunity activation. The identification of novel groups of genes up-regulated upon antiviral immunity activation serves as useful resource for mining new antiviral sensors and effectors.
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DNA Viral/imunologia , Embrião de Mamíferos/imunologia , Fibroblastos/imunologia , Imunidade Inata , RNA de Cadeia Dupla/imunologia , RNA Viral/imunologia , Transcriptoma/imunologia , Animais , DNA Viral/farmacologia , Embrião de Mamíferos/citologia , Camundongos , RNA de Cadeia Dupla/farmacocinética , RNA Viral/farmacologia , Transcriptoma/efeitos dos fármacosRESUMO
Metabolic reprograming controlling macrophage activation and function is emerging as new regulatory circuit on shaping immune responses. Generally, lipopolysaccharides (LPS)-induced pro-inflammatory activated macrophages, known as M1 macrophages, display higher glycolysis. In contrast, interleukin-4 (IL-4)-skewed anti-inflammatory activated macrophages, known as M2 macrophages, mainly rely on oxidative phosphorylation for their bioenergetic demands. Emerging evidence reveals that these metabolic preferences further fine-tune macrophage polarization process, including signaling cascades and epigenetic reprogramming. Thus, specific nutrient microenvironments may affect inflammatory responses of macrophages by intervening these metabolic machineries. How to measure the metabolic switch of macrophages both in vitro and in vivo is an important issue for understanding immunometabolic regulations in macrophages. Here, we describe a basic protocol for examining how glutamine metabolism affects macrophage polarization by using the Extracellular Flux (XF(e)96) Analyzer (Seahorse Bioscience), which takes real-time measurements of oxidative phosphorylation and glycolysis. We also present a detailed procedure for detecting the expression of inflammatory genes in polarized macrophages under glutamine-replete or -deprived conditions.
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Ativação de Macrófagos/imunologia , Espectrometria de Massas/métodos , Análise do Fluxo Metabólico/métodos , Metabolômica/métodos , Animais , Biomarcadores/análise , Biomarcadores/metabolismo , Células Cultivadas , Glutamina/metabolismo , Glicólise/imunologia , Lipopolissacarídeos/imunologia , Macrófagos/imunologia , Macrófagos/metabolismo , Espectrometria de Massas/instrumentação , Análise do Fluxo Metabólico/instrumentação , Redes e Vias Metabólicas/imunologia , Metabolômica/instrumentação , Camundongos , Camundongos Endogâmicos C57BL , Fosforilação Oxidativa , Consumo de Oxigênio/imunologia , Cultura Primária de Células/instrumentação , Cultura Primária de Células/métodos , Organismos Livres de Patógenos EspecíficosRESUMO
Chronic inflammation underlies the development of metabolic diseases and individuals with metabolic disease often also suffer from delayed wound healing due to prolonged inflammation. Resolving inflammation provides a therapeutic strategy in treating metabolic diseases. We previously showed that during an anti-inflammatory response when macrophages were alternatively (M2) polarized, retinoic acid (RA) dramatically activated arginase 1 gene (Arg1), a gene crucial for wound healing. Here we report that a widely used sulfonylurea drug for type 2 diabetes mellitus (T2DM), glyburide, enhances the anti-inflammatory response and synergizes with RA to promote wound healing. Our data also delineate the mechanism underlying glyburide's anti-inflammatory effect, which is to stimulate the degradation of a pro-inflammatory regulator, Receptor Interacting Protein 140 (RIP140), by activating Ca2+/calmodulin-dependent protein kinase II (CamKII) that triggers specific ubiquitination of RIP140 for degradation. By stimulating RIP140 degradation, glyburide enhances M2 polarization and anti-inflammation. Using a high-fat diet induced obesity mouse model to monitor wound healing effects, we provide a proof-of-concept for a therapeutic strategy that combining glyburide and RA can significantly improve wound healing. Mechanistically, this study uncovers a new mechanism of action of glyburide and a new pathway modulating RIP140 protein degradation that is mediated by CamKII signaling.
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Glibureto/farmacologia , Correpressor 1 de Receptor Nuclear/metabolismo , Tretinoína/farmacologia , Cicatrização/efeitos dos fármacos , Animais , Proteína Quinase Tipo 2 Dependente de Cálcio-Calmodulina/metabolismo , Células Cultivadas , Dieta Hiperlipídica , Sinergismo Farmacológico , Macrófagos Peritoneais/efeitos dos fármacos , Macrófagos Peritoneais/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Obesidade/etiologia , Fosforilação/efeitos dos fármacos , Células RAW 264.7 , Transdução de Sinais/efeitos dos fármacos , UbiquitinaçãoRESUMO
Orchestrating biological activities of immune cells through metabolic reprogramming reveals a new approach to harnessing immune responses. Increasing evidence reveals that the mitochondrion is a central regulator for modulating metabolic reprogramming and controlling immune cell activation and functions. In addition to supporting bioenergetic demands, the mitochondrion serves as a signaling platform through the generation of reactive oxygen species and metabolites of the tricarboxylic acid cycle to modulate signaling cascades controlling immune cell activation and immune responses. Herein, we discuss the mechanisms through which the mitochondrion acts as a master regulator to fine-tune immune responses elicited by macrophages and T cells.
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Metabolismo Energético , Imunidade Inata/imunologia , Macrófagos/imunologia , Doenças Metabólicas/imunologia , Mitocôndrias/imunologia , Mitocôndrias/metabolismo , Linfócitos T/imunologia , Animais , Humanos , Doenças Metabólicas/patologia , Mitocôndrias/patologia , Transdução de SinaisRESUMO
Glutamine metabolism provides synergistic support for macrophage activation and elicitation of desirable immune responses; however, the underlying mechanisms regulated by glutamine metabolism to orchestrate macrophage activation remain unclear. Here we show that the production of α-ketoglutarate (αKG) via glutaminolysis is important for alternative (M2) activation of macrophages, including engagement of fatty acid oxidation (FAO) and Jmjd3-dependent epigenetic reprogramming of M2 genes. This M2-promoting mechanism is further modulated by a high αKG/succinate ratio, whereas a low ratio strengthens the proinflammatory phenotype in classically activated (M1) macrophages. As such, αKG contributes to endotoxin tolerance after M1 activation. This study reveals new mechanistic regulations by which glutamine metabolism tailors the immune responses of macrophages through metabolic and epigenetic reprogramming.
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Reprogramação Celular/imunologia , Epigênese Genética , Ácidos Cetoglutáricos/imunologia , Ativação de Macrófagos/imunologia , Macrófagos/imunologia , Animais , Imunoprecipitação da Cromatina , Ciclo do Ácido Cítrico/imunologia , Ácidos Graxos/metabolismo , Perfilação da Expressão Gênica , Glutamina/metabolismo , Glicólise/imunologia , Ácidos Cetoglutáricos/metabolismo , Lipopolissacarídeos , Macrófagos/metabolismo , Metabolômica , Camundongos , NF-kappa B/imunologia , Oxirredução , Fosforilação Oxidativa , Fenótipo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Análise de Sequência de RNA , Ácido Succínico/metabolismoRESUMO
The success of cancer immunotherapy reveals the power of host immunity on killing cancer cells and the feasibility to unleash restraints of anti-tumor immunity. However, the immunosuppressive tumor microenvironment and low immunogenicity of cancer cells restrict the therapeutic efficacy of cancer immunotherapies in a small fraction of patients. Therefore deciphering the underlying mechanisms promoting the generation of an immunosuppressive tumor microenvironment is direly needed to better harness host anti-tumor immunity. Early works revealed that deregulated metabolic activities in cancer cells support unrestricted proliferation and survival by producing macromolecules. Intriguingly, recent studies uncovered that metabolic switch in immune and endothelial cells modulate cellular activities and contribute to the progression of several diseases, including cancers. Herein, we review the progress on immunometabolic regulations on fine-tuning activities of immune cells and discuss how metabolic communication between cancer and infiltrating immune cells contributes to cancer immune evasion. Moreover, we would like to discuss how we might exploit this knowledge to improve current immunotherapies and the unresolved issues in this field.
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Macrophage classical (M1) versus alternative (M2) polarization is critical for the homeostatic control of innate immunity. Uncontrolled macrophage polarization is frequently implicated in diseases. This study reports a new functional role for receptor-interacting protein 140 (RIP140) in regulating this phenotypic switch. RIP140 is required for M1 activation, and its degradation is critical to LPS-induced endotoxin tolerance (ET). Here, we found that failure to establish RIP140 degradation-mediated ET prevents M2 polarization, and reducing RIP140 level facilitates an M1/M2 switch, resulting in more efficient wound healing in animal models generated with either transgenic or bone marrow transplant procedures. The M2-suppressive effect is elicited by a new function of RIP140 that, in macrophages exposed to M2 cues, is exported to cytosol, forming complexes with CAPNS1 (calpain regulatory subunit) to activate calpain 1/2, that activates PTP1B phosphatase. The activated PTP1B then reduces STAT6 phosphorylation, thereby suppressing the efficiency of M2 polarization. It is concluded that RIP140 plays dual roles in regulating the M1-M2 phenotype switch: the first, in the nucleus, is an M1 enhancer and the second, in the cytosol, is an M2 suppressor. Modulating the level and/or subcellular distribution of RIP140 can be a new therapeutic strategy for diseases where inflammatory/anti-inflammatory responses are critical.
Assuntos
Proteínas Adaptadoras de Transdução de Sinal/imunologia , Calpaína/metabolismo , Ativação de Macrófagos , Macrófagos/imunologia , Proteínas Nucleares/imunologia , Proteína Tirosina Fosfatase não Receptora Tipo 1/metabolismo , Fator de Transcrição STAT6/química , Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Animais , Calpaína/imunologia , Linhagem Celular Tumoral , Núcleo Celular/imunologia , Núcleo Celular/metabolismo , Polaridade Celular , Citosol/imunologia , Citosol/metabolismo , Endotoxinas/imunologia , Células HEK293 , Humanos , Tolerância Imunológica , Imunidade Inata , Lipopolissacarídeos/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Proteínas Nucleares/metabolismo , Proteína 1 de Interação com Receptor Nuclear , Fosforilação , Proteína Tirosina Fosfatase não Receptora Tipo 1/imunologia , Proteólise , Fator de Transcrição STAT6/imunologia , Transdução de Sinais , CicatrizaçãoRESUMO
We recently exploited a transgenic approach to coerce macrophage anti-inflammatory M2 polarization in vivo by lowering Receptor Interacting Protein 140 (RIP140) level in macrophages (mφRIP140KD), which induced browning of white adipose tissue (WAT). In vitro, conditioned medium from cultured adipose tissue macrophages (ATMs) of mφRIP140KD mice could trigger preadipocytes' differentiation into beige cells. Here we describe a cell therapy for treating high fat diet (HFD)-induced insulin resistance (IR). Injecting M2 ATMs retrieved from the WAT of mφRIP140KD mice into HFD-fed obese adult wild-type mice effectively triggers their WAT browning, reduces their pro-inflammatory responses, and improves their insulin sensitivity. These data provide a proof-of-concept that delivering engineered anti-inflammatory macrophages can trigger white fat browning, stimulate whole-body thermogenesis, and reduce obesity-associated IR.
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A "Holy Grail" sought in medical treatment of obesity is to be able to biologically reprogram their adipose tissues to burn fat rather than store it. White adipose tissue (WAT) stores fuel and its expansion underlines insulin resistance (IR) whereas brown adipose tissue (BAT) burns fuel and stimulates insulin sensitivity. These two types of fats seesaw within our bodies via a regulatory mechanism that involves intricate communication between adipocytes and blood cells, particularly macrophages that migrate into adipose deposits. The coregulator, Receptor Interacting Protein 140 (RIP140), plays a key role in regulating this communication. In mice on a high-fat diet, the level of RIP140 in macrophages is dramatically elevated to activate their inflammatory M1 polarization and enhance their recruitment into WAT, facilitating IR. Conversely, lowering the level of RIP140 in macrophages not only reduces M1 macrophages but also expands alternatively polarized, anti-inflammatory M2 macrophages, triggering white adipose tissue browning, fat burning, and restoration of insulin sensitivity. This suggests a potential therapeutic strategy for reversing IR, obesity, and atherosclerotic or even cosmetic fat deposits: therapeutic browning of white adipose deposits by diminishing RIP140 levels in macrophages.
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Atherosclerosis, a syndrome with abnormal arterial walls, is one of the major causes that lead to the development of various cardiovascular diseases. The key initiator of atherosclerosis is cholesterol accumulation. The uncontrolled cholesterol deposition, mainly involving low-density lipoprotein (LDL), causes atheroma plaque formation, which initiates chronic inflammation due to the recruitment of inflammatory cells such as macrophages. Macrophages scavenge excess peripheral cholesterol and transport intracellular cholesterol to high-density lipoprotein (HDL) for excretion or storage. Cholesterol-laden macrophage-derived foam cell formation is the main cause of atherogenesis. It is critical to understand the regulatory mechanism of cholesterol homeostasis in the macrophage in order to prevent foam cells formation and further develop novel therapeutic strategies against atherosclerosis. Here we identified a protein, RIP140 (receptor interacting protein 140), which enhances macrophage-derived foam cell formation by reducing expression of reverse cholesterol transport genes, A TP-binding membrane cassette transporter A-1 (ABCA1) and ATP-binding membrane cassette transporter G-1 (ABCG1). In animal models, we found that reducing RIP140 levels by crossing macrophage-specific RIP140 knockdown (MÏRIP140KD) mice with ApoE null mice effectively ameliorates high-cholesterol diet-induced atherosclerosis. Our data suggest that reducing RIP140 levels in macrophages significantly inhibits atherosclerosis, along with markers of inflammation and the number of macrophages in a western diet fed ApoE null mouse. This study provides a proof-of-concept for RIP140 as a risk biomarker of, and a therapeutic target for, atherosclerosis.
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Proteínas Adaptadoras de Transdução de Sinal/metabolismo , Aterosclerose/metabolismo , Aterosclerose/patologia , Colesterol/metabolismo , Células Espumosas/metabolismo , Homeostase , Proteínas Nucleares/metabolismo , Transportadores de Cassetes de Ligação de ATP/metabolismo , Acetilação/efeitos dos fármacos , Animais , Apolipoproteínas E/deficiência , Apolipoproteínas E/metabolismo , Transporte Biológico/efeitos dos fármacos , Dieta Ocidental , Células Espumosas/efeitos dos fármacos , Técnicas de Silenciamento de Genes , Homeostase/efeitos dos fármacos , Lipoproteínas LDL/farmacologia , Receptores X do Fígado , Lisina/metabolismo , Camundongos Transgênicos , Proteína 1 de Interação com Receptor Nuclear , Receptores Nucleares Órfãos/metabolismoRESUMO
Adipose tissue macrophage (ATM) recruitment and activation play a critical role in obesity-induced inflammation and insulin resistance (IR). The mechanism regulating ATM activation and infiltration remains unclear. In this study, we found receptor interacting protein 140 (RIP140) can regulate the dynamics of ATM that contribute to adipose tissue remodeling. A high-fat diet (HFD) elevates RIP140 expression in macrophages. We generated mice with RIP140 knockdown in macrophages using transgenic and bone marrow transplantation procedures to blunt HFD-induced elevation in RIP140. We detected significant white adipose tissue (WAT) browning and improved systemic insulin sensitivity in these mice, particularly under an HFD feeding. These mice have decreased circulating monocyte population and altered ATM profile in WAT (a dramatic reduction in inflammatory classically activated macrophages [M1] and expansion in alternatively activated macrophages [M2]), which could improve HFD-induced IR. These studies suggest that reducing RIP140 expression in monocytes/macrophages can be a new therapeutic strategy in treating HFD-induced and inflammation-related diseases.