RESUMO
In tandem with the expanding obesity pandemic, the prevalence of metabolic dysfunction associated steatohepatitis (MASH, formerly known as NASH)- driven hepatocellular carcinoma (HCC) is predicted to rise globally, creating a significant need for therapeutic interventions. We previously identified the upregulation of apoptosis antagonizing transcription factor (AATF), which is implicated in facilitating the progression from MASH to HCC. The objective of this study was to examine whether the intervention of curcumin could alleviate AATF-mediated MASH, inhibit tumor growth, and elucidate the underlying mechanism. A preclinical murine model mimicking human MASH-HCC was employed, subjecting mice to either a chow diet normal water (CDNW) or western diet sugar water (WDSW) along with very low dose of carbon tetrachloride (CCl4 - 0.2 µL/g, weekly). Mice receiving curcumin (CUR) alongside WDSW/CCl4 exhibited significant improvements, including reduced liver enzymes, dyslipidemia, steatosis, inflammation, and hepatocellular ballooning. Curcumin treatment also suppressed hepatic expression of inflammatory, fibrogenic, and oncogenic markers. Of note, there was a significant reduction in the expression of AATF upon curcumin treatment in WDSW/CCl4 mice and human HCC cells. In contrast, curcumin upregulated Kruppel-like factor 4 (KLF4) in MASH liver and HCC cells, which is known to downregulate sp1 (specificity protein-1) expression. Thus, curcumin treatment effectively inhibited the progression of MASH to HCC by downregulating the expression of AATF via the KLF4-Sp1 signaling pathway. These preclinical findings establish a novel molecular connection between curcumin and AATF in reducing hepatocarcinogenesis, and provide a strong rationale for the development of curcumin as a viable treatment for MASH-HCC in humans.
Assuntos
Carcinoma Hepatocelular , Curcumina , Fígado Gorduroso , Neoplasias Hepáticas , Hepatopatia Gordurosa não Alcoólica , Animais , Humanos , Camundongos , Apoptose , Proteínas Reguladoras de Apoptose , Carcinoma Hepatocelular/patologia , Curcumina/farmacologia , Curcumina/uso terapêutico , Fígado Gorduroso/patologia , Inflamação/tratamento farmacológico , Inflamação/patologia , Neoplasias Hepáticas/patologia , Hepatopatia Gordurosa não Alcoólica/tratamento farmacológico , Hepatopatia Gordurosa não Alcoólica/metabolismo , Proteínas Repressoras , Fatores de TranscriçãoRESUMO
Extracellular vesicles (EVs) are nanoscopic packages that are heterogeneous and bona fide players in hepatic physiology and pathology as they are involved in intercellular communication. EVs carrying bioactive cargoes rich in lipids, proteins or nucleic acids are implicated in the onset and progression of liver diseases. Liver pathology using liver biopsy has been assessed for several intricate conditions such as viral hepatitis, alcoholic and non-alcoholic fatty liver disease, hepatic malignancies and drug-induced liver injury. The lacunae, however, lie in early diagnosis and timely treatment of the above conditions, underscoring the need for non-invasive, accurate diagnostic tools that could replace the gold standard method of tissue biopsy. In this regard, EVs have emerged as promising candidates that could serve as potential biomarkers. In the last two decades, EVs, owing to their multifaceted charm in bringing out cell-free therapeutic responses and the ability of their cargoes to be applied to novel biomarkers, have drawn the great attention of researchers with the advancement and clinical application of liquid biopsy. In this review, we recapitulate the role of EVs and provide insights into the promising role of these small packages as biomarkers in liver pathology.
Assuntos
Vesículas Extracelulares , Hepatopatia Gordurosa não Alcoólica , Humanos , Biomarcadores/metabolismo , Vesículas Extracelulares/metabolismo , Vesículas Extracelulares/patologia , Hepatopatia Gordurosa não Alcoólica/diagnóstico , Hepatopatia Gordurosa não Alcoólica/metabolismo , Comunicação CelularRESUMO
The pathophysiology of nonalcoholic steatohepatitis (NASH) is complex, owing to its diverse pathological drivers and, until recently, there were no approved drugs for this disease. Tecomella is a popular herbal medicine used to treat hepatosplenomegaly, hepatitis, and obesity. However, the potential role of Tecomella undulata in NASH has not yet been scientifically investigated. The administration of Tecomella undulata via oral gavage lowered body weight, insulin resistance, alanine transaminase (ALT), aspartate transaminase (AST), triglycerides, and total cholesterol in western diet sugar water (WDSW) fed mice but had no effect on chow diet normal water (CDNW) fed mice. Tecomella undulata improved steatosis, lobular inflammation, and hepatocyte ballooning and resolved NASH in WDSW mice. Furthermore, Tecomella undulata also alleviated the WDSW-induced Endoplasmic Reticulum stress and oxidative stress, enhanced antioxidant status, and thus reduced inflammation in the treated mice. Of note, these effects were comparable to saroglitazar, the approved drug used to treat human NASH and the positive control used in the study. Thus, our findings indicate the potential of Tecomella undulata to ameliorate WDSW-induced steatohepatitis, and these preclinical data provide a strong rationale for assessing Tecomella undulata for the treatment of NASH.
Assuntos
Hepatopatia Gordurosa não Alcoólica , Humanos , Camundongos , Animais , Hepatopatia Gordurosa não Alcoólica/patologia , Fígado/patologia , Hepatomegalia , Obesidade/patologia , Inflamação/patologia , Camundongos Endogâmicos C57BL , Modelos Animais de DoençasRESUMO
BACKGROUND AND AIMS: The mechanisms by which the I148M mutant variant of the patatin-like phospholipase domain-containing 3 (PNPLA3I148M ) drives development of nonalcoholic steatohepatitis (NASH) are not known. The aim of this study was to obtain insights on mechanisms underlying PNPLA3I148M -induced acceleration of NASH. APPROACH AND RESULTS: Hepatocyte-specific overexpression of empty vector (luciferase), human wild-type PNPLA3, or PNPLA3I148M was achieved using adeno-associated virus 8 in a diet-induced mouse model of nonalcoholic fatty liver disease followed by chow diet or high-fat Western diet with ad libitum administration of sugar in drinking water (WDSW) for 8 weeks. Under WDSW, PNPLA3I148M overexpression accelerated steatohepatitis with increased steatosis, inflammation ballooning, and fibrosis (P < 0.001 versus other groups for all). Silencing PNPLA3I148M after its initial overexpression abrogated these findings. PNPLA3I148M caused 22:6n3 docosahexanoic acid depletion and increased ceramides under WDSW in addition to increasing triglycerides and diglycerides, especially enriched with unsaturated fatty acids. It also increased oxidative stress and endoplasmic reticulum stress. Increased total ceramides was associated with signature of transducer and activator of transcription 3 (STAT3) activation with downstream activation of multiple immune-inflammatory pathways at a transcriptomic level by network analyses. Silencing PNPLA3I148M reversed STAT3 activation. Conditioned media from HepG2 cells overexpressing PNPLA3I148M increased procollagen mRNA expression in LX2 cells; this was abrogated by hepatocyte STAT3 inhibition. CONCLUSIONS: Under WDSW, PNPLA3I148M overexpression promotes steatosis and NASH by metabolic reprogramming characterized by increased triglycerides and diglycerides, n3 polyunsaturated fatty acid depletion, and increased ceramides with resultant STAT3 phosphorylation and downstream inflammatory pathway activation driving increased stellate cell fibrogenic activity.
Assuntos
Lipase , Cirrose Hepática , Proteínas de Membrana , Hepatopatia Gordurosa não Alcoólica , Animais , Dieta Hiperlipídica/efeitos adversos , Dieta Ocidental/efeitos adversos , Modelos Animais de Doenças , Progressão da Doença , Expressão Gênica , Células Hep G2 , Células Estreladas do Fígado/metabolismo , Hepatócitos/metabolismo , Humanos , Lipase/genética , Cirrose Hepática/etiologia , Cirrose Hepática/metabolismo , Cirrose Hepática/patologia , Cirrose Hepática/fisiopatologia , Masculino , Proteínas de Membrana/genética , Camundongos , Camundongos Endogâmicos C57BL , Mutação , Hepatopatia Gordurosa não Alcoólica/etiologia , Hepatopatia Gordurosa não Alcoólica/genética , Hepatopatia Gordurosa não Alcoólica/metabolismo , Hepatopatia Gordurosa não Alcoólica/fisiopatologia , Polimorfismo Genético , TranscriptomaRESUMO
Apoptosis antagonizing transcription factor (AATF), an interacting partner of RNA polymerase II is a multifunctional protein that is highly conserved in eukaryotes. In addition to the regulation of gene expression as a transcriptional coactivator, AATF is shown to play a dual role in regulating the cell cycle by displacing histone deacetylases 1 (HDAC1) from the retinoblastoma-E2F transcription factor (Rb-E2F) complex and also from the specificity protein 1 (Sp1) transcription factor responsible for p21 expression, thereby ensuring cell proliferation and growth arrest, respectively, at different checkpoints of the cell cycle. Notably, AATF has emerged as one of the most important modulators of various cellular responses such as proliferation, apoptosis, and survival. Studies have demonstrated that AATF protects cells from multiple stress stimuli such as DNA damage, ER stress, hypoxia, or glucose deprivation by inducing cell cycle arrest, autophagy, or apoptosis inhibition. Furthermore, AATF serves as a critical regulator in various cancers and promotes tumorigenesis by protecting cancer cells from apoptosis induction, favoring cell proliferation, or promoting cell survival by autophagy. Recent studies have demonstrated the key role of AATF in ribosome biosynthesis and have also provided insights into the mechanistic role of AATF, offering impressive cytoprotection in myocardial infarction, neurologic diseases, and nephronophthisis. In this review, we will provide a comprehensive overview of the role of AATF and shed light on its emerging roles underlining the potential use of AATF as a novel biomarker and as an effective therapeutic target.
Assuntos
Proteínas Reguladoras de Apoptose/metabolismo , Pontos de Checagem do Ciclo Celular/fisiologia , Proliferação de Células/fisiologia , Fatores de Transcrição/metabolismo , Animais , Humanos , Proteínas Repressoras/genética , Transdução de Sinais/fisiologiaRESUMO
Hepatocellular carcinoma (HCC) is increasing as a cause of liver-related mortality largely because of the growing burden of nonalcoholic steatohepatitis (NASH). The mechanisms of HCC development in nonalcoholic fatty liver disease (NAFLD) are incompletely understood. We initially identified apoptosis antagonizing transcription factor (AATF) to be associated with HCC in a mouse model of NASH that develops HCC without the addition of specific carcinogens. AATF, also called che-1, is a transcriptional factor that is highly conserved among eukaryotes. AATF is known to be a central mediator of the cellular responses as it promotes cell proliferation and survival by inducing cell cycle arrest, autophagy, DNA repair, and inhibition of apoptosis. However, the role of AATF in NASH and HCC remains unknown. Here, we provide evidence for AATF as a contributory factor for HCC in NAFLD. AATF overexpression was further verified in human NASH and HCC and multiple human HCC cell lines. Tumor necrosis factor-α (TNFα), known to be increased in NASH, induced AATF expression. Promoter analysis of AATF revealed a sterol regulatory element binding transcription factor 1-c (SREBP-1c) binding site; inhibition of SREBP-1 by using specific inhibitors as well as small interfering RNA decreased TNFα-induced AATF expression. AATF interacted with signal transducer and activator of transcription 3 to increase monocyte chemoattractant protein-1 expression. AATF knockdown decreased cell proliferation, migration, invasion, colony formation, and anchorage-dependent growth in HCC cell lines. Xenograft of QGY-7703 HCC cells with AATF stably knocked down into nonobese diabetic scid gamma mice demonstrated reduced tumorigenesis and metastases. Conclusion: AATF drives NAFLD and hepatocarcinogenesis, offering a potential target for therapeutic intervention.
Assuntos
Proteínas Reguladoras de Apoptose/metabolismo , Carcinoma Hepatocelular/metabolismo , Neoplasias Hepáticas/metabolismo , Hepatopatia Gordurosa não Alcoólica/metabolismo , Proteínas Repressoras/metabolismo , Animais , Carcinoma Hepatocelular/etiologia , Quimiocina CCL2/metabolismo , Células Hep G2 , Humanos , Neoplasias Hepáticas/etiologia , Masculino , Camundongos , Hepatopatia Gordurosa não Alcoólica/complicações , Fator de Transcrição STAT3/metabolismo , Proteína de Ligação a Elemento Regulador de Esterol 1/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Regulação para CimaRESUMO
The histologic spectrum of nonalcoholic fatty liver disease (NAFLD) includes fatty liver (NAFL) and steatohepatitis (NASH), which can progress to cirrhosis in up to 20% of NASH patients. Bile acids (BA) are linked to the pathogenesis and therapy of NASH. We (1) characterized the plasma BA profile in biopsy-proven NAFL and NASH and compared to controls and (2) related the plasma BA profile to liver histologic features, disease activity, and fibrosis. Liquid chromatography/mass spectrometry quantified BAs. Descriptive statistics, paired and multiple group comparisons, and regression analyses were performed. Of 86 patients (24 controls, 25 NAFL, and 37 NASH; mean age 51.8 years and body mass index 31.9 kg/m2 ), 66% were women. Increased total primary BAs and decreased secondary BAs (both P < 0.05) characterized NASH. Total conjugated primary BAs were significantly higher in NASH versus NAFL (P = 0.047) and versus controls (P < 0.0001). NASH had higher conjugated to unconjugated chenodeoxycholate (P = 0.04), cholate (P = 0.0004), and total primary BAs (P < 0.0001). The total cholate to chenodeoxycholate ratio was significantly higher in NAFLD without (P = 0.005) and with (P = 0.02) diabetes. Increased key BAs were associated with higher grades of steatosis (taurocholate), lobular (glycocholate) and portal inflammation (taurolithocholate), and hepatocyte ballooning (taurocholate). Conjugated cholate and taurocholate directly and secondary to primary BA ratio inversely correlated to NAFLD activity score. A higher ratio of total secondary to primary BA decreased (odds ratio, 0.57; P = 0.004) and higher conjugated cholate increased the likelihood of significant fibrosis (F≥2) (P = 0.007). Conclusion: NAFLD is associated with significantly altered circulating BA composition, likely unaffected by type 2 diabetes, and correlated with histological features of NASH; these observations provide the foundation for future hypothesis-driven studies of specific effects of BAs on specific aspects of NASH. (Hepatology 2018;67:534-548).
Assuntos
Ácidos e Sais Biliares/sangue , Hepatopatia Gordurosa não Alcoólica/sangue , Adulto , Idoso , Estudos Transversais , Feminino , Humanos , Cirrose Hepática/sangue , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Receptores Citoplasmáticos e Nucleares/fisiologia , Índice de Gravidade de DoençaRESUMO
Intestinal dysbiosis is implicated in alcoholic hepatitis (AH). However, changes in the circulating microbiome, its association with the presence and severity of AH, and its functional relevance in AH is unknown. Qualitative and quantitative assessment of changes in the circulating microbiome were performed by sequencing bacterial DNA in subjects with moderate AH (MAH) (n = 18) or severe AH (SAH) (n = 19). These data were compared with heavy drinking controls (HDCs) without obvious liver disease (n = 19) and non-alcohol-consuming controls (NACs, n = 20). The data were related to endotoxin levels and markers of monocyte activation. Linear discriminant analysis effect size (LEfSe) analysis, inferred metagenomics, and predictive functional analysis using PICRUSt were performed. There was a significant increase in 16S copies/ng DNA both in MAH (P < 0.01) and SAH (P < 0.001) subjects. Compared with NACs, the relative abundance of phylum Bacteroidetes was significantly decreased in HDCs, MAH, and SAH (P < 0.001). In contrast, all alcohol-consuming groups had enrichment with Fusobacteria; this was greatest for HDCs and decreased progressively in MAH and SAH. Subjects with SAH had significantly higher endotoxemia (P = 0.01). Compared with alcohol-consuming groups, predictive functional metagenomics indicated an enrichment of bacteria with genes related to methanogenesis and denitrification. Furthermore, both HDCs and SAH showed activation of a type III secretion system that has been linked to gram-negative bacterial virulence. Metagenomics in SAH versus NACs predicted increased isoprenoid synthesis via mevalonate and anthranilate degradation, known modulators of gram-positive bacterial growth and biofilm production, respectively. CONCLUSION: Heavy alcohol consumption appears to be the primary driver of changes in the circulating microbiome associated with a shift in its inferred metabolic functions. (Hepatology 2018;67:1284-1302).
Assuntos
DNA Bacteriano/sangue , Hepatite Alcoólica/microbiologia , Hepatopatias Alcoólicas/microbiologia , Metagenômica/métodos , Microbiota/genética , Adulto , Consumo de Bebidas Alcoólicas/efeitos adversos , DNA Bacteriano/genética , Endotoxinas/sangue , Feminino , Humanos , Fígado/microbiologia , Fígado/patologia , Masculino , Pessoa de Meia-Idade , Monócitos/patologiaRESUMO
Non-alcoholic fatty liver disease (NAFLD) can manifest as non-alcoholic fatty liver (NAFL) or non-alcoholic steatohepatitis (NASH). NASH is often associated with progressive fibrosis which can lead to cirrhosis and hepatocellular carcinoma (HCC). NASH is increasing as an aetiology for end-stage liver disease as well as HCC. There are currently no approved therapies for NASH. A major barrier to development of therapeutics for NASH is the lack of preclinical models of disease that are appropriately validated to represent the biology and outcomes of human disease. Many in vitro and animal models have been developed. In vitro models do not fully capture the hepatic and extrahepatic milieu of human NASH and large animal models are expensive and logistically difficult to use. Therefore, there is considerable interest in the development and validation of mouse models for NAFLD, including NASH. Several models based on varying genetic or dietary manipulations have been developed. However, the majority do not recreate steatohepatitis, strictly defined as the presence of hepatocellular ballooning with or without Mallory-Denk bodies, accompanied by inflammation in the presence of macrovesicular steatosis. Others lack validation against human disease. Herein, we describe the best practices in development of mouse models of NASH. We further review existing models and the literature supporting their use as a surrogate for human disease. Finally, data on models to evaluate protective genes are discussed. It is hoped that this review will provide guidance for the interpretation of data derived from mouse models and also for the development and validation of newer models.
Assuntos
Avaliação Pré-Clínica de Medicamentos/métodos , Hepatopatia Gordurosa não Alcoólica/terapia , Animais , Modelos Animais de Doenças , Progressão da Doença , HumanosRESUMO
The physiological role of the TGR5 receptor in the pancreas is not fully understood. We previously showed that activation of TGR5 in pancreatic ß cells by bile acids induces insulin secretion. Glucagon released from pancreatic α cells and glucagon-like peptide 1 (GLP-1) released from intestinal L cells regulate insulin secretion. Both glucagon and GLP-1 are derived from alternate splicing of a common precursor, proglucagon by PC2 and PC1, respectively. We investigated whether TGR5 activation in pancreatic α cells enhances hyperglycemia-induced PC1 expression thereby releasing GLP-1, which in turn increases ß cell mass and function in a paracrine manner. TGR5 activation augmented a hyperglycemia-induced switch from glucagon to GLP-1 synthesis in human and mouse islet α cells by GS/cAMP/PKA/cAMP-response element-binding protein-dependent activation of PC1. Furthermore, TGR5-induced GLP-1 release from α cells was via an Epac-mediated PKA-independent mechanism. Administration of the TGR5 agonist, INT-777, to db/db mice attenuated the increase in body weight and improved glucose tolerance and insulin sensitivity. INT-777 augmented PC1 expression in α cells and stimulated GLP-1 release from islets of db/db mice compared with control. INT-777 also increased pancreatic ß cell proliferation and insulin synthesis. The effect of TGR5-mediated GLP-1 from α cells on insulin release from islets could be blocked by GLP-1 receptor antagonist. These results suggest that TGR5 activation mediates cross-talk between α and ß cells by switching from glucagon to GLP-1 to restore ß cell mass and function under hyperglycemic conditions. Thus, INT-777-mediated TGR5 activation could be leveraged as a novel way to treat type 2 diabetes mellitus.
Assuntos
Ácidos Cólicos/farmacologia , Diabetes Mellitus Experimental/genética , Peptídeo 1 Semelhante ao Glucagon/metabolismo , Glucose/metabolismo , Comunicação Parácrina/genética , Receptores Acoplados a Proteínas G/agonistas , Animais , Derivados de Benzeno/farmacologia , Benzenossulfonatos/farmacologia , Linhagem Celular , Proteínas Quinases Dependentes de AMP Cíclico/genética , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Diabetes Mellitus Experimental/tratamento farmacológico , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Experimental/patologia , Diabetes Mellitus Tipo 2/genética , Diabetes Mellitus Tipo 2/metabolismo , Diabetes Mellitus Tipo 2/patologia , Estrenos/farmacologia , Regulação da Expressão Gênica , Peptídeo 1 Semelhante ao Glucagon/biossíntese , Peptídeo 1 Semelhante ao Glucagon/genética , Células Secretoras de Glucagon/efeitos dos fármacos , Células Secretoras de Glucagon/metabolismo , Células Secretoras de Glucagon/patologia , Homeostase/efeitos dos fármacos , Humanos , Resistência à Insulina , Células Secretoras de Insulina/efeitos dos fármacos , Células Secretoras de Insulina/metabolismo , Células Secretoras de Insulina/patologia , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Transgênicos , Pró-Proteína Convertase 1/genética , Pró-Proteína Convertase 1/metabolismo , Pró-Proteína Convertase 2/genética , Pró-Proteína Convertase 2/metabolismo , Pirrolidinonas/farmacologia , Receptores Acoplados a Proteínas G/genética , Receptores Acoplados a Proteínas G/metabolismo , Transdução de Sinais , Sulfonas/farmacologiaRESUMO
The effect of proinflammatory cytokines on the expression and activity of soluble guanylyl cyclase (sGC) and cGMP-phosphodiesterases (PDEs) was determined in intestinal longitudinal smooth muscle. In control muscle cells, cGMP levels are regulated via activation of sGC and PDE5; the activity of the latter is regulated via feedback phosphorylation by cGMP-dependent protein kinase. In muscle cells isolated from muscle strips cultured with interleukin-1ß (IL-1ß) or tumor necrosis factor α (TNF-α) or obtained from the colon of TNBS (2,4,6-trinitrobenzene sulfonic acid)-treated mice, expression of inducible nitric oxide synthase (iNOS) was induced and sGC was S-nitrosylated, resulting in attenuation of nitric oxide (NO)-induced sGC activity and cGMP formation. The effect of cytokines on sGC S-nitrosylation and activity was blocked by the iNOS inhibitor 1400W [N-([3-(aminomethyl)phenyl]methyl)ethanimidamide dihydrochloride]. The effect of cytokines on cGMP levels measured in the absence of IBMX (3-isobutyl-1-methylxanthine), however, was partly reversed by 1400W or PDE1 inhibitor vinpocetine and completely reversed by a combination of 1400W and vinpocetine. Expression of PDE1A was induced and was accompanied by an increase in PDE1A activity in muscle cells isolated from muscle strips cultured with IL-1ß or TNF-α or obtained from the colon of TNBS-treated mice; the effect of cytokines on PDE1 expression and activity was blocked by MG132 (benzyl N-[(2S)-4-methyl-1-[[(2S)-4-methyl-1-[[(2S)-4-methyl-1-oxopentan-2-yl]amino]-1-oxopentan-2-yl]amino]-1-oxopentan-2-yl]carbamate), an inhibitor of nuclear factor κB activity. NO-induced muscle relaxation was inhibited in longitudinal muscle cells isolated from muscle strips cultured with IL-1ß or TNF-α or obtained from the colon of TNBS-treated mice, and this inhibition was completely reversed by the combination of both 1400W and vinpocetine. Inhibition of smooth muscle relaxation during inflammation reflects the combined effects of decreased sGC activity via S-nitrosylation and increased cGMP hydrolysis via PDE1 expression.
Assuntos
Nucleotídeo Cíclico Fosfodiesterase do Tipo 1/biossíntese , Regulação Enzimológica da Expressão Gênica , Guanilato Ciclase/biossíntese , Relaxamento Muscular/fisiologia , Músculo Liso/enzimologia , Óxido Nítrico Sintase Tipo II/biossíntese , Receptores Citoplasmáticos e Nucleares/biossíntese , Animais , Citocinas/toxicidade , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Relaxamento Muscular/efeitos dos fármacos , Músculo Liso/efeitos dos fármacos , Guanilil Ciclase SolúvelRESUMO
This study identified a distinctive pattern of expression and activity of adenylyl cyclase (AC) and phosphodiesterase (PDE) isoforms in mouse colonic longitudinal smooth muscle cells and determined the changes in their expression and/or activity in response to proinflammatory cytokines (IL-1ß and TNF-α) in vitro and 2,4,6 trinitrobenzene sulphonic acid (TNBS)-induced colonic inflammation in vivo. AC5/6 and PDE4D5, expressed in circular muscle cells, were also expressed in longitudinal smooth muscle. cAMP formation was tightly regulated via feedback phosphorylation of AC5/6 and PDE4D5 by PKA. Inhibition of PKA activity by myristoylated PKI blocked phosphorylation of AC5/6 and PDE4D5 and enhanced cAMP formation. TNBS treatment in vivo and IL-1ß and TNF-α in vitro induced inducible nitric oxide synthase (iNOS) expression, stimulated ERK1/2 activity, caused iNOS-mediated S-nitrosylation and inhibition of AC5/6, and induced phosphorylation of PDE4D5 and stimulated its activity. The resultant decrease in AC5/6 activity and increase in PDE4D5 activity decreased cAMP formation and smooth muscle relaxation. S-nitrosylation and inhibition of AC5/6 activity were reversed by the iNOS inhibitor 1400W, whereas phosphorylation and activation of PDE4D5 were reversed by the phosphatidylinositol 3-kinase inhibitor LY294002 and the ERK1/2 inhibitor PD98059. The effects of IL-1ß or TNF-α on forskolin-stimulated cAMP formation and smooth muscle relaxation reflected inhibition of AC5/6 activity and activation of PDE4D5 and were partly reversed by 1400W or PD98059 and completely reversed by a combination of the two inhibitors. The changes in the cAMP/PKA signaling and smooth muscle relaxation contribute to colonic dysmotility during inflammation.
Assuntos
Adenilil Ciclases/metabolismo , Colite/enzimologia , Colo/enzimologia , Nucleotídeo Cíclico Fosfodiesterase do Tipo 4/metabolismo , Citocinas/metabolismo , Motilidade Gastrointestinal , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Proteína Quinase 3 Ativada por Mitógeno/metabolismo , Músculo Liso/enzimologia , Óxido Nítrico Sintase Tipo II/metabolismo , Inibidores de Adenilil Ciclases , Animais , Colite/induzido quimicamente , Colite/imunologia , Colite/fisiopatologia , Colo/efeitos dos fármacos , Colo/imunologia , Colo/fisiopatologia , AMP Cíclico/metabolismo , Proteínas Quinases Dependentes de AMP Cíclico/metabolismo , Modelos Animais de Doenças , Regulação para Baixo , Ativação Enzimática , Inibidores Enzimáticos/farmacologia , Motilidade Gastrointestinal/efeitos dos fármacos , Mediadores da Inflamação/metabolismo , Interleucina-1beta/metabolismo , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Proteína Quinase 1 Ativada por Mitógeno/antagonistas & inibidores , Proteína Quinase 3 Ativada por Mitógeno/antagonistas & inibidores , Relaxamento Muscular , Músculo Liso/efeitos dos fármacos , Músculo Liso/imunologia , Músculo Liso/fisiopatologia , Óxido Nítrico Sintase Tipo II/antagonistas & inibidores , Fosforilação , Transdução de Sinais , Ácido Trinitrobenzenossulfônico , Fator de Necrose Tumoral alfa/metabolismo , Regulação para CimaRESUMO
The signaling pathways mediating sustained contraction of mouse colonic longitudinal smooth muscle and the mechanisms involved in hypercontractility of this muscle layer in response to cytokines and TNBS-induced colitis have not been fully explored. In control longitudinal smooth muscle cells, ACh acting via m3 receptors activated sequentially Gα12, RhoGEF (LARG), and the RhoA/Rho kinase pathway. There was abundant expression of MYPT1, minimal expression of CPI-17, and a notable absence of a PKC/CPI-17 pathway. LARG expression was increased in longitudinal muscle cells isolated from muscle strips cultured for 24 h with IL-1ß or TNF-α or obtained from the colon of TNBS-treated mice. The increase in LARG expression was accompanied by a significant increase in ACh-stimulated Rho kinase and ZIP kinase activities, and sustained muscle contraction. The increase in LARG expression, Rho kinase and ZIP kinase activities, and sustained muscle contraction was abolished in cells pretreated with the Jun kinase inhibitor, SP600125. Expression of the MLCP activator, telokin, and MLCP activity were also decreased in longitudinal muscle cells from TNBS-treated mice or from strips treated with IL-1ß or TNF-α. In contrast, previous studies had shown that sustained contraction in circular smooth muscle is mediated by sequential activation of Gα13, p115RhoGEF, and dual RhoA-dependent pathways involving phosphorylation of MYPT1 and CPI-17. In colonic circular smooth muscle cells isolated from TNBS-treated mice or from strips treated with IL-1ß or TNF-α, CPI-17 expression and sustained muscle contraction were decreased. The disparate changes in the two muscle layers contribute to intestinal dysmotility during inflammation.
Assuntos
Colite/metabolismo , Inflamação/genética , Proteínas Quinases JNK Ativadas por Mitógeno/metabolismo , Músculo Liso/metabolismo , Fatores de Troca de Nucleotídeo Guanina Rho/biossíntese , Animais , Colite/induzido quimicamente , Colite/patologia , Colo/metabolismo , Proteínas Quinases Associadas com Morte Celular/metabolismo , Regulação da Expressão Gênica/efeitos dos fármacos , Inflamação/metabolismo , Inflamação/patologia , Camundongos , Contração Muscular/genética , Músculo Liso/patologia , Quinase de Cadeia Leve de Miosina/biossíntese , Técnicas de Cultura de Órgãos , Fragmentos de Peptídeos/biossíntese , Fosforilação/efeitos dos fármacos , Fatores de Troca de Nucleotídeo Guanina Rho/metabolismo , Transdução de Sinais/genética , Ácido Trinitrobenzenossulfônico/toxicidadeRESUMO
Others and we have characterized several Gßγ-dependent effectors in smooth muscle, including G protein-coupled receptor kinase 2 (GRK2), PLCß3, and phosphatidylinositol (PI) 3-kinase-γ, and have identified various signaling targets downstream of PI 3-kinase-γ, including cSrc, integrin-linked kinase, and Rac1-Cdc42/p21-activated kinase/p38 MAP kinase. This study identified a novel mechanism whereby Gßγ acting via PI 3-kinase-γ and cSrc exerts an inhibitory influence on Gαi activity. The Gi2-coupled δ-opioid receptor agonist d-penicillamine (2,5)-enkephalin (DPDPE) activated cSrc, stimulated tyrosine phosphorylation of Gαi2, and induced regulator of G protein signaling 12 (RGS12) association; all three events were blocked by PI 3-kinase (LY294002) and cSrc (PP2) inhibitors and by expression of the COOH-terminal sequence of GRK2-(495-689), a Gßγ-scavenging peptide. Inhibition of forskolin-stimulated cAMP and muscle relaxation by DPDPE was augmented by PP2, LY294002, and a selective PI 3-kinase-γ inhibitor, AS-605420. Expression of tyrosine-deficient (Y69F, Y231F, or Y321F) Gαi2 mutant or knockdown of RGS12 blocked Gαi2 phosphorylation and Gαi2-RGS12 association and caused greater inhibition of cAMP. Parallel studies using somatostatin, cyclopentyl adenosine, or ACh to activate, respectively, Gi1-coupled somatostatin (sstr3) receptors, and Gi3-coupled adenosine A1 or muscarinic m2 receptors elicited cSrc activation, Gαi1 or Gαi3 phosphorylation, Gαi1-RGS12 or Gαi3-RGS12 association, and inhibition of cAMP. Inhibition of cAMP and muscle relaxation was greatly increased by AS-605240 and PP2. The results demonstrate that Gßγ-dependent tyrosine phosphorylation of Gαi1/2/3 by cSrc facilitated recruitment of RGS12, a Gαi-specific RGS protein with a unique phosphotyrosine-binding domain, resulting in rapid deactivation of Gαi and facilitation of smooth muscle relaxation.
Assuntos
Subunidade alfa Gi2 de Proteína de Ligação ao GTP/metabolismo , Subunidades beta da Proteína de Ligação ao GTP/metabolismo , Subunidades gama da Proteína de Ligação ao GTP/metabolismo , Relaxamento Muscular , Miócitos de Músculo Liso/enzimologia , Fosfatidilinositol 3-Quinase/metabolismo , Proteínas Proto-Oncogênicas pp60(c-src)/metabolismo , Proteínas RGS/metabolismo , Estômago/enzimologia , Agonistas do Receptor A1 de Adenosina/farmacologia , Analgésicos Opioides/farmacologia , Animais , Células Cultivadas , AMP Cíclico/metabolismo , Ativação Enzimática , Retroalimentação Fisiológica , Subunidade alfa Gi2 de Proteína de Ligação ao GTP/genética , Agonistas Muscarínicos/farmacologia , Relaxamento Muscular/efeitos dos fármacos , Mutação , Miócitos de Músculo Liso/efeitos dos fármacos , Inibidores de Fosfoinositídeo-3 Quinase , Fosforilação , Inibidores de Proteínas Quinases/farmacologia , Proteínas Proto-Oncogênicas pp60(c-src)/antagonistas & inibidores , Proteínas RGS/genética , Interferência de RNA , Coelhos , Receptor A1 de Adenosina/efeitos dos fármacos , Receptor A1 de Adenosina/metabolismo , Receptor Muscarínico M2/agonistas , Receptor Muscarínico M2/metabolismo , Receptores Opioides delta/agonistas , Receptores Opioides delta/metabolismo , Receptores de Somatostatina/agonistas , Receptores de Somatostatina/metabolismo , Transdução de Sinais , Estômago/citologia , Estômago/efeitos dos fármacos , Transfecção , TirosinaRESUMO
Recent studies have identified AMP-activated kinase (AMPK) as a target of Ca(2+)/calmodulin-dependent kinase kinase (CaMKKß) and a negative regulator of myosin light-chain (MLC) kinase (MLCK). The present study examined whether a change in expression or activity of AMPK is responsible for hypercontractility of intestinal longitudinal muscle during inflammation or in response to proinflammatory cytokines. In mouse colonic longitudinal muscle cells, acetylcholine (ACh) stimulated AMPK and MLCK phosphorylation and activity and induced MLC20 phosphorylation and muscle contraction. Blockade of CaMKKß with STO609 (7-oxo-7H-benzimidazo[2,1-a]benz[de]isoquinoline-3-carboxylic acid acetate) inhibited AMPK and MLCK phosphorylation and augmented MLCK activity, MLC20 phosphorylation, and smooth muscle cell contraction. In muscle cells isolated from the colon of TNBS (2,4,6-trinitrobenzenesulfonic acid)-treated mice or from strips treated with interleukin-1ß or tumor necrosis factor-α, nuclear factor κB was activated as indicated by an increase in p65 phosphorylation and IκBα degradation, and AMPK was phosphorylated at a cAMP-dependent protein kinase (PKA)-specific site (Ser(485)) that is distinct from the stimulatory CaMKKß site (Thr(172)), resulting in attenuation of ACh-stimulated AMPK activity and augmentation of MLCK activity and muscle cell contraction. Inhibition of nuclear factor-κB activity with MG-132 (carbobenzoxy-L-leucyl-L-leucyl-L-leucinal Z-LLL-CHO) or PKA activity with myristoylated PKA inhibitor 14-22 amide blocked phosphorylation of AMPK at Ser(485) and restored MLCK activity and muscle cell contraction to control levels. The results imply that PKA released from IκBα complex phosphorylated AMPK at a PKA-specific site and inhibited its activity, thereby relieving the inhibitory effect of AMPK on MLCK and increasing MLCK activity and muscle cell contraction. We conclude that hypercontractility of intestinal longitudinal muscle induced by inflammation or proinflammatory cytokines is mediated by nuclear factor κB/PKA-dependent inhibition of AMPK and activation of MLCK.
Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Colo/metabolismo , Citocinas/farmacologia , Músculo Liso/metabolismo , Quinase de Cadeia Leve de Miosina/metabolismo , Acetilcolina/farmacologia , Animais , Benzimidazóis/farmacologia , Quinase da Proteína Quinase Dependente de Cálcio-Calmodulina/antagonistas & inibidores , Proteínas de Transporte/farmacologia , Colite/induzido quimicamente , Colite/metabolismo , Colo/efeitos dos fármacos , Interações Medicamentosas , Interleucina-1beta/farmacologia , Leupeptinas/farmacologia , Masculino , Camundongos , Contração Muscular/efeitos dos fármacos , Músculo Liso/efeitos dos fármacos , Cadeias Leves de Miosina/metabolismo , NF-kappa B/antagonistas & inibidores , NF-kappa B/metabolismo , Naftalimidas/farmacologia , Fragmentos de Peptídeos/farmacologia , Fosforilação/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Ácido Trinitrobenzenossulfônico/farmacologia , Fator de Necrose Tumoral alfa/farmacologiaRESUMO
A sedentary lifestyle and physical inactivity leads to metabolic syndrome-associated comorbidities involving abdominal obesity, type 2 diabetes, hyperlipidaemia associated Cardiovascular Diseases (CVDs), and Metabolic dysfunction-associated fatty liver disease (MAFLD). In this study, we evaluated the novel hepato/cardio/adipo-protective role of Quercetin via Vitamin D Receptor, and elucidated its underlying mechanisms in reducing lipotoxicity, inflammation and fibrosis in high calorie diet induced metabolic syndrome. Male Swiss albino mice were fed with western diet and sugar water for multiple time intervals. Anti-lipotoxicity, anti-inflammatory, and anti-fibrotic effect of Quercetin was assessed by Oil Red O, H&E and TMS staining at different time points. The lipid profile, mRNA expression of inflammatory markers (TNF- α, IL-1ß, IL-6 and MCP-1), fibrotic markers (α-SMA, COL1A1, COL1A2), adiponectin, AdipoR2, and VDR expression levels were measured from RNA pools of adipose, liver and heart tissues. Also, lipid-lowering and anti-steatohepatitic effects of Quercetin was assessed using mouse 3T3-L1 adipocytes, rat H9c2 cardiac cells, and human HepG2 hepatocytes. Our results indicate that, western diet fed mice with Quercetin ameliorated lipid profile and lipotoxicity. Histopathological examination and gene expression data revealed that Quercetin reduced hepatic and cardiac inflammation and fibrosis-associated markers. Interestingly, Quercetin treatment increased the serum levels of adiponectin and mRNA expressions of AdipoR2 and VDR. In-vitro experiments revealed the reduction in lipid accumulation of 3T3-L1 and fatty-acid-treated hepatic and cardiac cells following Quercetin treatment. These findings indicate that Quercetin exhibits a protective role on multiple organs through VDR activation and subsequent Adipo/AdipoR2 signaling in metabolic syndrome associated obesity, hepatic injury, and cardiac dysfunction.
RESUMO
Metabolic dysfunction-associated steatohepatitis-driven hepatocellular carcinoma (MASH-HCC) is a global clinical challenge for which there is a limited understanding of disease pathogenesis and a subsequent lack of therapeutic interventions. We previously identified that tumor necrosis factor-alpha (TNF-α) upregulated apoptosis antagonizing transcription factor (AATF) in MASH. Here, we investigated the effect of TNF-α converting enzyme (TACE) inhibition as a promising targeted therapy against AATF-mediated steatohepatitis to hepatocarcinogenesis. A preclinical murine model that recapitulates human MASH-HCC was used in the study. C57Bl/6 mice were fed with chow diet normal water (CD) or western diet sugar water (WD) along with a low dose of carbon tetrachloride (CCl4; 0.2 µL·g-1, weekly) for 24 weeks. TACE activity, TNF-α levels, and AATF expression were measured. The mice were treated with the TACE inhibitor Marimastat for 12 weeks, followed by analyses of liver injury, fibrosis, inflammation, and oncogenic signaling. In vitro experiments using stable clones of AATF control and AATF knockdown were also conducted. We found that AATF expression was upregulated in WD/CCl4 mice, which developed severe MASH at 12 weeks and advanced fibrosis with HCC at 24 weeks. WD/CCl4 mice showed increased TACE activity with reduced hepatic expression of sirtuin 1 (Sirt1) and tissue inhibitor of metalloproteinase 3 (Timp3). The involvement of the SIRT1/TIMP3/TACE axis was confirmed by the release of TNF-α, which upregulated AATF, a key molecular driver of MASH-HCC. Interestingly, TACE inhibition by Marimastat reduced liver injury, dyslipidemia, AATF expression, and oncogenic signaling, effectively preventing hepatocarcinogenesis. Furthermore, Marimastat inhibited the activation of JNK, ERK1/2, and AKT, which are key regulators of tumorigenesis in WD/CCl4 mice and in AATF control cells, but had no effect on AATF knockdown cells. This study shows that TACE inhibition prevents AATF-mediated inflammation, fibrosis, and oncogenesis in MASH-HCC, offering a potential target for therapeutic intervention.
Assuntos
Proteína ADAM17 , Carcinoma Hepatocelular , Neoplasias Hepáticas , Camundongos Endogâmicos C57BL , Animais , Humanos , Masculino , Camundongos , Proteína ADAM17/metabolismo , Proteína ADAM17/antagonistas & inibidores , Proteína ADAM17/genética , Carcinogênese/patologia , Carcinogênese/efeitos dos fármacos , Carcinogênese/metabolismo , Carcinogênese/genética , Carcinoma Hepatocelular/patologia , Carcinoma Hepatocelular/metabolismo , Carcinoma Hepatocelular/tratamento farmacológico , Carcinoma Hepatocelular/genética , Fígado Gorduroso/patologia , Fígado Gorduroso/metabolismo , Neoplasias Hepáticas/metabolismo , Neoplasias Hepáticas/patologia , Neoplasias Hepáticas/genética , Neoplasias Hepáticas/tratamento farmacológico , Fator de Necrose Tumoral alfa/metabolismoRESUMO
Caveolae are specialized regions of the plasma membrane that concentrate receptors and associated signaling molecules critical in regulation of cellular response to transmitters and hormones. We have determined the effects of caveolin-1 (Cav-1) deletion, caveolin-1 siRNA, and caveolar disruption in mice on the signaling pathways that mediate contraction and relaxation in colonic smooth muscle and on the components of the peristaltic reflex in isolated tissue and propulsion in intact colonic segments. In Cav-1-/- mice, both relaxation and contraction were decreased in smooth muscle cells and muscle strips, as well as during both phases of the peristaltic reflex and colonic propulsion. The decrease in relaxation in response to the nitric oxide (NO) donor was accompanied by a decrease in cGMP levels and an increase in phosphodiesterase 5 (PDE5) activity. Relaxation by a PDE5-resistant cGMP analog was not affected in smooth muscle of Cav-1-/- mice, suggesting that inhibition of relaxation was due to augmentation of PDE5 activity. Similar effects on relaxation, PDE5 and cGMP were obtained in muscle cells upon disruption of caveolae by methyl-ß-cyclodextrin or suppression of Cav-1. Sustained contraction mediated via inhibition of myosin light chain phosphatase (MLCP) activity is regulated by Rho kinase and PKC via phosphorylation of two endogenous inhibitors of MLCP: myosin phosphatase-targeting subunit (MYPT1) and 17-kDa PKC-potentiated protein phosphatase 1 inhibitor protein (CPI-17), respectively. The activity of both enzymes and phosphorylation of MYPT1 and CPI-17 were decreased in smooth muscle from Cav-1-/- mice. We conclude that the integrity of caveolae is essential for contractile and relaxant activity in colonic smooth muscle and the maintenance of neuromuscular function at organ level.
Assuntos
Caveolina 1/farmacologia , Colo , Nucleotídeo Cíclico Fosfodiesterase do Tipo 5/metabolismo , Peristaltismo , Proteína Quinase C/metabolismo , Quinases Associadas a rho/metabolismo , Animais , Colo/metabolismo , Colo/fisiologia , Trânsito Gastrointestinal/efeitos dos fármacos , Trânsito Gastrointestinal/fisiologia , Camundongos , Camundongos Endogâmicos C57BL , Modelos Animais , Músculo Liso/metabolismo , Músculo Liso/fisiologia , Fosfatase de Miosina-de-Cadeia-Leve/metabolismo , Peristaltismo/efeitos dos fármacos , Peristaltismo/fisiologia , Transdução de Sinais/fisiologia , beta-Ciclodextrinas/metabolismoRESUMO
The present study characterized the TGR5 expression and the signaling pathways coupled to this receptor that mediates the relaxation of gastric smooth muscle. TGR5 was detected in gastric muscle cells by RT-PCR and Western blotting. Treatment of cells with the TGR5-selective ligand oleanolic acid (OA) activated Gαs, but not Gαq, Gαi1, Gαi2, or Gαi3, and increased cAMP levels. OA did not elicit contraction, but caused relaxation of carbachol-induced contraction of gastric muscle cells from wild-type mice, but not tgr5(-/-) mice. OA, but not a selective exchange protein activated by cAMP (Epac) ligand (8-pCPT-2'-O-Me-cAMP), caused phosphorylation of RhoA and the phosphorylation was blocked by the PKA inhibitor, myristoylated PKI, and by the expression of phosphorylation-deficient mutant RhoA (S188A). Both OA and Epac ligand stimulated Ras-related protein 1 (Rap1) and inhibited carbachol (CCh)-induced Rho kinase activity. Expression of RhoA (S188A) or PKI partly reversed the inhibition of Rho kinase activity by OA but had no effect on inhibition by Epac ligand. However, suppression of Rap1 with siRNA blocked the inhibition of Rho kinase by Epac ligand, and partly reversed the inhibition by OA; the residual inhibition was blocked by PKI. Muscle relaxation in response to OA, but not Epac ligand, was partly reversed by PKI. We conclude that activation of TGR5 causes relaxation of gastric smooth muscle and the relaxation is mediated through inhibition of RhoA/Rho kinase pathway via both cAMP/Epac-dependent stimulation of Rap1 and cAMP/PKA-dependent phosphorylation of RhoA at Ser(188). TGR5 receptor activation on smooth muscle reveals a novel mechanism for the regulation of gut motility by bile acids.