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1.
Proc Natl Acad Sci U S A ; 116(45): 22692-22698, 2019 11 05.
Artigo em Inglês | MEDLINE | ID: mdl-31636200

RESUMO

Genome-wide association studies found that increased risk for atrial fibrillation (AF), the most common human heart arrhythmia, is associated with noncoding sequence variants located in proximity to PITX2 Cardiomyocyte-specific epigenomic and comparative genomics uncovered 2 AF-associated enhancers neighboring PITX2 with varying conservation in mice. Chromosome conformation capture experiments in mice revealed that the Pitx2c promoter directly contacted the AF-associated enhancer regions. CRISPR/Cas9-mediated deletion of a 20-kb topologically engaged enhancer led to reduced Pitx2c transcription and AF predisposition. Allele-specific chromatin immunoprecipitation sequencing on hybrid heterozygous enhancer knockout mice revealed that long-range interaction of an AF-associated region with the Pitx2c promoter was required for maintenance of the Pitx2c promoter chromatin state. Long-range looping was mediated by CCCTC-binding factor (CTCF), since genetic disruption of the intronic CTCF-binding site caused reduced Pitx2c expression, AF predisposition, and diminished active chromatin marks on Pitx2 AF risk variants located at 4q25 reside in genomic regions possessing long-range transcriptional regulatory functions directed at PITX2.


Assuntos
Fibrilação Atrial/genética , Elementos Facilitadores Genéticos , Predisposição Genética para Doença , Proteínas de Homeodomínio/genética , Regiões Promotoras Genéticas , Fatores de Transcrição/genética , Animais , Sistemas CRISPR-Cas , Mapeamento Cromossômico , Epigênese Genética , Estudo de Associação Genômica Ampla , Camundongos , Camundongos Knockout , Proteína Homeobox PITX2
2.
FASEB J ; 33(1): 711-721, 2019 01.
Artigo em Inglês | MEDLINE | ID: mdl-30024790

RESUMO

Coordinated changes in signaling pathways and gene expression in hearts subjected to prolonged stress maintain cardiac function. Loss of steroid receptor coactivator-2 (SRC-2) results in a reversal to the fetal gene program and disrupts the response to pressure overload, accompanied by prominent effects on metabolism and growth signaling, including increased AMPK activation. We proposed that early metabolic stress driven by AMPK activation induces contractile dysfunction in mice lacking SRC-2. We used 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) to activate AMPK transiently before transverse aortic constriction (TAC) in wild-type and cardiomyocyte-specific SRC-2 knockout (CKO) animals. In contrast to AMPK activities during stress, in unstressed hearts, AICAR induced a mild activation of Akt signaling, and, in SRC-2-CKO mice, partially relieved an NAD+ deficiency and increased antioxidant signaling. These molecular changes translated to a mild hypertrophic response to TAC with decreased maladaptive remodeling, including markedly decreased fibrosis. Additionally, preactivation of AMPK in SRC-2-CKO mice was accompanied by a dramatic improvement in cardiac function compared with saline-treated SRC-2-CKO mice. Our results show that altered molecular signaling before stress onset has extended effects on sustained cardiac stress responses, and prestress modulation of transient growth and metabolism pathways may control those effects.-Nam, D. H., Kim, E., Benham, A., Park, H.-K., Soibam, B., Taffet, G. E., Kaelber, J. T., Suh, J. H., Taegtmeyer, H., Entman, M. L., Reineke, E. L. Transient activation of AMPK preceding left ventricular pressure overload reduces adverse remodeling and preserves left ventricular function.


Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Aminoimidazol Carboxamida/análogos & derivados , Cardiomegalia/prevenção & controle , Coativador 2 de Receptor Nuclear/fisiologia , Ribonucleotídeos/farmacologia , Função Ventricular Esquerda/fisiologia , Pressão Ventricular , Remodelação Ventricular/fisiologia , Proteínas Quinases Ativadas por AMP/genética , Aminoimidazol Carboxamida/farmacologia , Animais , Cardiomegalia/etiologia , Cardiomegalia/metabolismo , Hipoglicemiantes/farmacologia , Masculino , Camundongos , Camundongos Knockout , Miócitos Cardíacos/citologia , Miócitos Cardíacos/efeitos dos fármacos , Miócitos Cardíacos/metabolismo , Disfunção Ventricular Esquerda/prevenção & controle , Função Ventricular Esquerda/efeitos dos fármacos , Remodelação Ventricular/efeitos dos fármacos
3.
J Biol Chem ; 292(52): 21643-21652, 2017 12 29.
Artigo em Inglês | MEDLINE | ID: mdl-29127200

RESUMO

Pressure overload-induced cardiac stress induces left ventricular hypertrophy driven by increased cardiomyocyte mass. The increased energetic demand and cardiomyocyte size during hypertrophy necessitate increased fuel and oxygen delivery and stimulate angiogenesis in the left ventricular wall. We have previously shown that the transcriptional regulator steroid receptor coactivator-2 (SRC-2) controls activation of several key cardiac transcription factors and that SRC-2 loss results in extensive cardiac transcriptional remodeling. Pressure overload in mice lacking SRC-2 induces an abrogated hypertrophic response and decreases sustained cardiac function, but the cardiomyocyte-specific effects of SRC-2 in these changes are unknown. Here, we report that cardiomyocyte-specific loss of SRC-2 (SRC-2 CKO) results in a blunted hypertrophy accompanied by a rapid, progressive decrease in cardiac function. We found that SRC-2 CKO mice exhibit markedly decreased left ventricular vasculature in response to transverse aortic constriction, corresponding to decreased expression of the angiogenic factor VEGF. Of note, SRC-2 knockdown in cardiomyocytes decreased VEGF expression and secretion to levels sufficient to blunt in vitro tube formation and proliferation of endothelial cells. During pressure overload, both hypertrophic and hypoxic signals can stimulate angiogenesis, both of which stimulated SRC-2 expression in vitro Furthermore, SRC-2 coactivated the transcription factors GATA-binding protein 4 (GATA-4) and hypoxia-inducible factor (HIF)-1α and -2α in response to angiotensin II and hypoxia, respectively, which drive VEGF expression. These results suggest that SRC-2 coordinates cardiomyocyte secretion of VEGF downstream of the two major angiogenic stimuli occurring during pressure overload bridging both hypertrophic and hypoxia-stimulated paracrine signaling.


Assuntos
Coativador 2 de Receptor Nuclear/metabolismo , Indutores da Angiogênese/metabolismo , Angiotensina II/metabolismo , Animais , Ventrículos do Coração/metabolismo , Hipertrofia Ventricular Esquerda/metabolismo , Subunidade alfa do Fator 1 Induzível por Hipóxia/metabolismo , Camundongos , Camundongos Knockout , Miocárdio/metabolismo , Miócitos Cardíacos/metabolismo , Miócitos Cardíacos/fisiologia , Neovascularização Patológica/metabolismo , Comunicação Parácrina/fisiologia , Ativação Transcricional , Fator A de Crescimento do Endotélio Vascular/metabolismo , Remodelação Ventricular
4.
Stem Cells ; 33(2): 416-28, 2015 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-25330987

RESUMO

Biological processes require close cooperation of multiple transcription factors that integrate different signals. Thyroid hormone receptors (TRs) induce Krüppel-like factor 9 (KLF9) to regulate neurogenesis. Here, we show that triiodothyronine (T3) also works through TR to induce KLF9 in HepG2 liver cells, mouse liver, and mouse and human primary hepatocytes and sought to understand TR/KLF9 network function in the hepatocyte lineage and stem cells. Knockdown experiments reveal that KLF9 regulates hundreds of HepG2 target genes and modulates T3 response. Together, T3 and KLF9 target genes influence pathways implicated in stem cell self-renewal and differentiation, including Notch signaling, and we verify that T3 and KLF9 cooperate to regulate key Notch pathway genes and work independently to regulate others. T3 also induces KLF9 in human embryonic stem cells (hESCs) and human induced pluripotent stem cells (hiPSC) and this effect persists during differentiation to definitive endoderm and hiPSC-derived hepatocytes. Microarray analysis reveals that T3 regulates hundreds of hESC and hiPSC target genes that cluster into many of the same pathways implicated in TR and KLF9 regulation in HepG2 cells. KLF9 knockdown confirms that TR and KLF9 cooperate to regulate Notch pathway genes in hESC and hiPSC, albeit in a partly cell-specific manner. Broader analysis of T3 responsive hESC/hiPSC genes suggests that TRs regulate multiple early steps in ESC differentiation. We propose that TRs cooperate with KLF9 to regulate hepatocyte proliferation and differentiation and early stages of organogenesis and that TRs exert widespread and important influences on ESC biology.


Assuntos
Diferenciação Celular/fisiologia , Hepatócitos/metabolismo , Fatores de Transcrição Kruppel-Like/metabolismo , Células-Tronco Pluripotentes/metabolismo , Receptores dos Hormônios Tireóideos/metabolismo , Transdução de Sinais/fisiologia , Animais , Feminino , Células Hep G2 , Hepatócitos/citologia , Humanos , Fatores de Transcrição Kruppel-Like/genética , Masculino , Camundongos , Células-Tronco Pluripotentes/citologia , Receptores Notch/genética , Receptores Notch/metabolismo , Receptores dos Hormônios Tireóideos/genética , Tri-Iodotironina/genética , Tri-Iodotironina/metabolismo
5.
Bioorg Med Chem Lett ; 26(8): 1889-93, 2016 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-26988304

RESUMO

We report the pharmacophore of the peroxisome proliferator-activated receptor δ (PPARδ) agonist natural product phosphoiodyn A is the phosphonate core. Synthesis of simplified phosphonate esters 13 and 15 provide structurally novel, highly selective and potent PPARδ agonists (EC50=78 and 112 nM, respectively). Further, both compounds demonstrate significant neuroprotective activity in an in vitro cellular model indicating that phosphonates may be an effective novel scaffold for the design of therapeutics for the treatment of neurodegenerative disorders.


Assuntos
Hidrocarbonetos Iodados/farmacologia , Doenças Neurodegenerativas/tratamento farmacológico , Fármacos Neuroprotetores/farmacologia , Compostos Organofosforados/farmacologia , PPAR delta/agonistas , PPAR beta/agonistas , Poli-Inos/farmacologia , Relação Dose-Resposta a Droga , Humanos , Hidrocarbonetos Iodados/síntese química , Hidrocarbonetos Iodados/química , Estrutura Molecular , Fármacos Neuroprotetores/síntese química , Fármacos Neuroprotetores/química , Compostos Organofosforados/síntese química , Compostos Organofosforados/química , Poli-Inos/síntese química , Poli-Inos/química , Relação Estrutura-Atividade
6.
Biochem Biophys Res Commun ; 457(1): 119-23, 2015 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-25511704

RESUMO

The glucocorticoid receptor (GR) N-terminal domain (NTD) contains a transactivation domain (activation function 1; AF-1). GR AF-1 is phosphorylated, but effects of this modification upon AF-1 activity and cofactor recruitment are not completely clear. GR AF-1 activity is mostly confined to a short unstructured domain called tau1c (amino acids 187-244) that contains three phosphorylation sites and binds a short cysteine rich fragment (CH3) of the coactivator CREB binding protein (CBP). Since the CH3 domain overlaps the CBP transcriptional adaptor zinc binding (TAZ) 2 domain, implicated in phosphorylation dependent binding to other unstructured transcription factor domains, we set out to investigate whether GR interacts with TAZ2 and whether this binding event is modulated by phosphorylation. We find that GR tau1c is absolutely required for enhancement of GR function and GR/CBP association in cultured cells. Tau1c interacts with TAZ2 in vitro and peptide mapping reveals CBP binding determinants throughout tau1c. Phosphorylation at GR Ser203, not involved in transactivation, does not affect tau1c/TAZ2 interactions. However, phosphorylation at Ser211 and Ser226, markers of GR transcriptional activity, greatly enhances TAZ2 binding in a synergistic fashion. We propose that GR tau1c phosphorylation could promote CBP recruitment and enhance AF-1 activity.


Assuntos
Proteína de Ligação a CREB/química , Proteína de Ligação a CREB/metabolismo , Receptores de Glucocorticoides/química , Receptores de Glucocorticoides/metabolismo , Ativação Transcricional , Sequência de Aminoácidos , Linhagem Celular , Humanos , Dados de Sequência Molecular , Peptídeos/química , Peptídeos/metabolismo , Fosforilação , Fosfosserina/metabolismo , Ligação Proteica , Estrutura Terciária de Proteína , Relação Estrutura-Atividade
7.
Nutrients ; 16(4)2024 Feb 12.
Artigo em Inglês | MEDLINE | ID: mdl-38398835

RESUMO

The probiotic Limosilactobacillus reuteri DSM 17938 produces anti-inflammatory effects in scurfy (SF) mice, a model characterized by immune dysregulation, polyendocrinopathy, enteropathy, and X-linked inheritance (called IPEX syndrome in humans), caused by regulatory T cell (Treg) deficiency and is due to a Foxp3 gene mutation. Considering the pivotal role of lipids in autoimmune inflammatory processes, we investigated alterations in the relative abundance of lipid profiles in SF mice (± treatment with DSM 17938) compared to normal WT mice. We also examined the correlation between plasma lipids and gut microbiota and circulating inflammatory markers. We noted a significant upregulation of plasma lipids associated with autoimmune disease in SF mice, many of which were downregulated by DSM 17938. The upregulated lipids in SF mice demonstrated a significant correlation with gut bacteria known to be implicated in the pathogenesis of various autoimmune diseases. Chronic hepatitis in SF livers responded to DSM 17938 treatment with a reduction in hepatic inflammation. Altered gene expression associated with lipid metabolism and the positive correlation between lipids and inflammatory cytokines together suggest that autoimmunity leads to dyslipidemia with impaired fatty acid oxidation in SF mice. Probiotics are presumed to contribute to the reduction of lipids by reducing inflammatory pathways.


Assuntos
Doenças Autoimunes , Limosilactobacillus reuteri , Probióticos , Humanos , Camundongos , Animais , Linfócitos T Reguladores , Hepatite Crônica/metabolismo , Hepatite Crônica/patologia , Probióticos/uso terapêutico , Lipídeos , Fatores de Transcrição Forkhead/genética
8.
Diabetes ; 73(5): 701-712, 2024 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-38320268

RESUMO

Bile acids (BAs) are pleiotropic regulators of metabolism. Elevated levels of hepatic and circulating BAs improve energy metabolism in peripheral organs, but the precise mechanisms underlying the metabolic benefits and harm still need to be fully understood. In the current study, we identified orosomucoid 2 (ORM2) as a liver-secreted hormone (i.e., hepatokine) induced by BAs and investigated its role in BA-induced metabolic improvements in mouse models of diet-induced obesity. Contrary to our expectation, under a high-fat diet (HFD), our Orm2 knockout (Orm2-KO) exhibited a lean phenotype compared with C57BL/6J control, partly due to the increased energy expenditure. However, when challenged with a HFD supplemented with cholic acid, Orm2-KO eliminated the antiobesity effect of BAs, indicating that ORM2 governs BA-induced metabolic improvements. Moreover, hepatic ORM2 overexpression partially replicated BA effects by enhancing insulin sensitivity. Mechanistically, ORM2 suppressed interferon-γ/STAT1 activities in inguinal white adipose tissue depots, forming the basis for anti-inflammatory effects of BAs and improving glucose homeostasis. In conclusion, our study provides new insights into the molecular mechanisms of BA-induced liver-adipose cross talk through ORM2 induction.


Assuntos
Ácidos e Sais Biliares , Orosomucoide , Camundongos , Animais , Ácidos e Sais Biliares/metabolismo , Orosomucoide/metabolismo , Orosomucoide/farmacologia , Camundongos Endogâmicos C57BL , Obesidade/genética , Obesidade/metabolismo , Fígado/metabolismo , Dieta Hiperlipídica/efeitos adversos
9.
Vitam Horm ; 123: 231-247, 2023.
Artigo em Inglês | MEDLINE | ID: mdl-37717986

RESUMO

Liver X receptors α and ß are members of the nuclear receptor family, which comprise a flexible N-terminal domain, a DNA binding domain, a hinge linker, and a ligand binding domain. Liver X receptors are important regulators of cholesterol and lipid homeostasis by controlling the transcription of numerous genes. Key to their transcriptional role is synergetic interaction among the domains. DNA binding domain binds on DNA; ligand binding domain is a crucial switch to control the transcription activity through conformational change caused by ligand binding. The Liver X receptors form heterodimers with retinoid X receptor and then the liganded heterodimer may recruit other necessary transcription components to form an active transcription complex.


Assuntos
Receptores X do Fígado , Humanos , Ligantes , Domínios Proteicos
10.
Mol Cells ; 46(9): 527-534, 2023 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-37691258

RESUMO

Liver ischemia-reperfusion injury (IRI) is the main cause of organ dysfunction and failure after liver surgeries including organ transplantation. The mechanism of liver IRI is complex and numerous signals are involved but cellular metabolic disturbances, oxidative stress, and inflammation are considered the major contributors to liver IRI. In addition, the activation of inflammatory signals exacerbates liver IRI by recruiting macrophages, dendritic cells, and neutrophils, and activating NK cells, NKT cells, and cytotoxic T cells. Technological advances enable us to understand the role of specific immune cells during liver IRI. Accordingly, therapeutic strategies to prevent or treat liver IRI have been proposed but no definitive and effective therapies exist yet. This review summarizes the current update on the immune cell functions and discusses therapeutic potentials in liver IRI. A better understanding of this complex and highly dynamic process may allow for the development of innovative therapeutic approaches and optimize patient outcomes.


Assuntos
Fígado , Traumatismo por Reperfusão , Humanos , Inflamação , Células Matadoras Naturais , Macrófagos
11.
Mol Metab ; 72: 101717, 2023 06.
Artigo em Inglês | MEDLINE | ID: mdl-37004989

RESUMO

OBJECTIVE: Mitophagy removes damaged mitochondria to maintain cellular homeostasis. Aryl hydrocarbon receptor (AhR) expression in the liver plays a crucial role in supporting normal liver functions, but its impact on mitochondrial function is unclear. Here, we identified a new role of AhR in the regulation of mitophagy to control hepatic energy homeostasis. METHODS: In this study, we utilized primary hepatocytes from AhR knockout (KO) mice and AhR knockdown AML12 hepatocytes. An endogenous AhR ligand, kynurenine (Kyn), was used to activate AhR in AML12 hepatocytes. Mitochondrial function and mitophagy process were comprehensively assessed by MitoSOX and mt-Keima fluorescence imaging, Seahorse XF-based oxygen consumption rate measurement, and Mitoplate S-1 mitochondrial substrate utilization analysis. RESULTS: Transcriptomic analysis indicated that mitochondria-related gene sets were dysregulated in AhR KO liver. In both primary mouse hepatocytes and AML12 hepatocyte cell lines, AhR inhibition strongly suppressed mitochondrial respiration rate and substrate utilization. AhR inhibition also blunted the fasting response of several essential autophagy genes and the mitophagy process. We further identified BCL2 interacting protein 3 (BNIP3), a mitophagy receptor that senses nutrient stress, as an AhR target gene. AhR is directly recruited to the Bnip3 genomic locus, and Bnip3 transcription was enhanced by AhR endogenous ligand treatment in wild-type liver and abolished entirely in AhR KO liver. Mechanistically, overexpression of Bnip3 in AhR knockdown cells mitigated the production of mitochondrial reactive oxygen species (ROS) and restored functional mitophagy. CONCLUSIONS: AhR regulation of the mitophagy receptor BNIP3 coordinates hepatic mitochondrial function. Loss of AhR induces mitochondrial ROS production and impairs mitochondrial respiration. These findings provide new insight into how endogenous AhR governs hepatic mitochondrial homeostasis.


Assuntos
Mitocôndrias , Receptores de Hidrocarboneto Arílico , Camundongos , Animais , Espécies Reativas de Oxigênio/metabolismo , Receptores de Hidrocarboneto Arílico/genética , Receptores de Hidrocarboneto Arílico/metabolismo , Ligantes , Mitocôndrias/metabolismo , Fígado/metabolismo , Camundongos Knockout , Homeostase
12.
Front Nutr ; 9: 831879, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35419389

RESUMO

The nutrient sensing nuclear receptor peroxisome proliferator-activated receptor-α (PPARα) regulates the host response to short-term fasting by inducing hepatic transcriptional programming of ketogenesis, fatty acid oxidation and transport, and autophagy. This adaptation is ineffective in chronically undernourished individuals, among whom dyslipidemia and hepatic steatosis are common. We recently reported that hepatic PPARα protein is profoundly depleted in male mice undernourished by a low-protein, low-fat diet. Here, we identify PPARα as a deacetylation target of the NAD-dependent deacetylase sirtuin-1 (SIRT1) and link this to the decrease in PPARα protein levels in undernourished liver. Livers from undernourished male mice expressed high levels of SIRT1, with decreased PPARα acetylation and strongly decreased hepatic PPARα protein. In cultured hepatocytes, PPARα protein levels were decreased by transiently transfecting constitutively active SIRT1 or by treating cells with the potent SIRT1 activator resveratrol, while silencing SIRT1 increased PPARα protein levels. SIRT1 expression is correlated with increased PPARα ubiquitination, suggesting that protein loss is due to proteasomal degradation. In accord with these findings, the dramatic loss of hepatic PPARα in undernourished male mice was completely restored by treating mice with the proteasome inhibitor bortezomib. Similarly, treating undernourished mice with the SIRT1 inhibitor selisistat/EX-527 completely restored hepatic PPARα protein. These data suggest that induction of SIRT1 in undernutrition results in hepatic PPARα deacetylation, ubiquitination, and degradation, highlighting a new mechanism that mediates the liver's failed adaptive metabolic responses in chronic undernutrition.

13.
Front Immunol ; 13: 846155, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35720380

RESUMO

Acute malnutrition, or wasting, is implicated in over half of all deaths in children under five and increases risk of infectious disease. Studies in humans and preclinical models have demonstrated that malnutrition is linked to an immature intestinal microbiota characterized by increased prevalence of Enterobacteriaceae. Observational studies in children with moderate acute malnutrition (MAM) have also observed heightened systemic inflammation and increased circulating bacterial lipopolysaccharides (LPS; endotoxin). However, the mechanisms that underpin the systemic inflammatory state and endotoxemia, and their pathophysiological consequences, remain uncertain. Understanding these pathophysiological mechanisms is necessary to design targeted treatments that will improve the unacceptable rate of failure or relapse that plague current approaches. Here we use a mouse model of MAM to investigate the mechanisms that promote inflammation in the malnourished host. We found that mice with MAM exhibited increased systemic inflammation at baseline, increased translocation of bacteria and bacterial LPS, and an exaggerated response to inflammatory stimuli. An exaggerated response to bacterial LPS was associated with increased acute weight loss. Remarkably, intestinal inflammation and barrier dysfunction was found in the cecum and colon. The cecum showed a dysbiotic microbiota with expansion of Gammaproteobacteria and some Firmicutes, and contraction of Bacteroidetes. These changes were paralleled by an increase in fecal LPS bioactivity. The inflammatory phenotype and weight loss was modulated by oral administration of non-absorbable antibiotics that altered the proportion of cecal Gammaproteobacteria. We propose that the heightened inflammation of acute malnutrition is the result of changes in the intestinal microbiota, intestinal barrier dysfunction in the cecum and colon, and increased systemic exposure to LPS.


Assuntos
Gastroenteropatias , Microbioma Gastrointestinal , Enteropatias , Desnutrição , Animais , Bactérias , Ceco/microbiologia , Inflamação , Lipopolissacarídeos , Camundongos , Redução de Peso
14.
Hepatol Commun ; 4(12): 1835-1850, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-33305154

RESUMO

Liver dysfunction, including coagulopathy, is a prominent feature of protein-energy malnutrition. To identify mechanisms underlying malnutrition-associated coagulopathy, we administered a low-protein low-fat diet to lactating dams and examined hepatic transcription and plasma coagulation parameters in young adult weanlings. Malnutrition impacted body composition to a greater extent in male versus female mice. Transcriptional profiles suggested opposing effects of nutrient-sensing nuclear receptors, namely induction of peroxisome proliferator-activated receptor α (PPARα) targets and repression of farnesoid-X-receptor (FXR) targets. Coagulopathy with decreased synthesis of fibrinogen-α (FGA) and factor 11 (F11) was observed in malnourished male animals but not female animals. In primary mouse hepatocytes, FXR agonist increased and PPARα agonist decreased Fga and F11 messenger RNA expression. Nuclear receptor DNA response elements were identified in the Fga and F11 gene regulatory regions, and opposing effects of FXR and PPARα were confirmed with luciferase assays. Unexpectedly, hepatic PPARα protein was markedly depleted in malnourished male liver and was not enriched on Fga or F11 response elements. Rather, there was loss of FXR binding at these response elements. Reduced PPARα protein was associated with loss of hepatocyte peroxisomes, which are necessary for bile acid biosynthesis, and with decreased concentrations of bile acids that function as FXR ligands, most notably the FXR agonist chenodeoxycholic acid. Conclusion: Malnutrition impairs growth and liver synthetic function more severely in male mice than in female mice. Malnourished male mice are coagulopathic and exhibit decreased hepatocyte peroxisomes, FXR agonist bile acids, FXR binding on Fga and F11 gene regulatory elements, and coagulation factor synthesis. These effects are absent in female mice, which have low baseline levels of PPARα, suggesting that nutrient-sensing nuclear receptors regulate coagulation factor synthesis in response to host nutritional status in a sex-specific manner.

15.
Neurogastroenterol Motil ; 32(12): e13936, 2020 12.
Artigo em Inglês | MEDLINE | ID: mdl-33021011

RESUMO

BACKGROUND: Slow gastrointestinal (GI) transit occurs in moderate-to-severe malnutrition. Mechanisms underlying malnutrition-associated dysmotility remain unknown, partially due to lack of animal models. This study sought to characterize GI dysmotility in mouse models of malnutrition. METHODS: Neonatal mice were malnourished by timed maternal separation. Alternatively, low-protein, low-fat diet was administered to dams, with malnourished neonates tested at two weeks or weaned to the same chow and tested as young adults. We determined total GI transit time by carmine red gavage, colonic motility by rectal bead latency, and both gastric emptying and small bowel motility with fluorescein isothiocyanate-conjugated dextran. We assessed histology with light microscopy, ex vivo contractility and permeability with force-transduction and Ussing chamber studies, and gut microbiota composition by 16S rDNA sequencing. KEY RESULTS: Both models of neonatal malnutrition and young adult malnourished males but not females exhibited moderate growth faltering, stunting, and grossly abnormal stomachs. Progression of fluorescent dye was impaired in both neonatal models of malnutrition, whereas gastric emptying was delayed only in maternally separated pups and malnourished young adult females. Malnourished young adult males but not females had atrophic GI mucosa, exaggerated intestinal contractile responses, and increased gut barrier permeability. These sex-specific abnormalities were associated with altered gut microbial communities. CONCLUSIONS & INFERENCES: Multiple models of early-life malnutrition exhibit delayed upper GI transit. Malnutrition affects young adult males more profoundly than females. These models will facilitate future studies to identify mechanisms underlying malnutrition-induced pathophysiology and sex-specific regulatory effects.


Assuntos
Gastroenteropatias/fisiopatologia , Motilidade Gastrointestinal/fisiologia , Desnutrição/fisiopatologia , Privação Materna , Caracteres Sexuais , Fatores Etários , Animais , Animais Recém-Nascidos , Feminino , Gastroenteropatias/etiologia , Gastroenteropatias/psicologia , Trânsito Gastrointestinal/fisiologia , Masculino , Desnutrição/complicações , Desnutrição/psicologia , Camundongos , Camundongos Endogâmicos C57BL
16.
Mol Cancer Res ; 6(2): 314-24, 2008 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-18245227

RESUMO

Sterol regulatory element-binding protein-1c (SREBP-1c) is a basic helix-loop-helix transcription factor that plays an important role in lipid homeostasis. Here, we show that SREBP-1c regulates androgen receptor (AR) transactivation through direct interaction with AR and represses androgen-dependent growth of prostatic cells. Transient transfection studies show that SREBP-1c specifically inhibits the transactivation of AR. Chromatin immunoprecipitation assays reveal that SREBP-1c is recruited with AR onto the endogenous AR target promoter. Moreover, adenovirus-mediated overexpression of SREBP-1c decreases the mRNA level of the prostate-specific antigen gene, an endogenous target gene of AR, supporting SREBP-1c modulation of AR transactivation. In vivo and in vitro protein interaction assays show that SREBP-1c directly interacts with AR through the activation function-1 domain of AR. In addition, transfection studies and glutathione S-transferase pull-down competition experiments reveal that the SREBP-1c-mediated repression of AR transactivation is accomplished through competition with certain AR coactivators for AR interaction. The SREBP-1c-mediated inhibition of AR transactivation also involves the recruitment of histone deacetylase 1. Finally, adenovirus-mediated overexpression of SREBP-1c inhibits androgen-induced proliferation of prostatic cells in vitro and in vivo, and small interfering RNA-mediated down-regulation of SREBP-1 enhances androgen-induced proliferation of prostatic cells as well as the transactivation of AR. Taken together, these results suggest that SREBP-1c acts as an AR corepressor and may play an important role in the regulation of AR-dependent prostatic cell growth.


Assuntos
Androgênios/farmacologia , Próstata/metabolismo , Próstata/patologia , Receptores Androgênicos/metabolismo , Proteína de Ligação a Elemento Regulador de Esterol 1/metabolismo , Ativação Transcricional/efeitos dos fármacos , Animais , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Histona Desacetilase 1 , Histona Desacetilases/metabolismo , Masculino , Camundongos , Regiões Promotoras Genéticas/genética , Próstata/efeitos dos fármacos , Próstata/enzimologia , Ligação Proteica/efeitos dos fármacos , Proteínas Repressoras/metabolismo , Transcrição Gênica/efeitos dos fármacos , Ensaios Antitumorais Modelo de Xenoenxerto
17.
Mol Endocrinol ; 22(1): 33-46, 2008 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-17885209

RESUMO

CR6-interacting factor 1 (CRIF1) was previously identified as a nuclear protein that interacts with members of the Gadd45 family and plays a role as a negative regulator in cell growth. However, the nuclear function of CRIF1 remains largely unknown. In this study, we demonstrate that CRIF1 acts as a novel corepressor of the androgen receptor (AR) in prostatic cells. Transient transfection studies show that CRIF1 specifically represses AR transcriptional activation of target promoters in a dose-dependent manner. Additionally, CRIF1 is recruited with AR to the endogenous AR target promoters. In vivo and in vitro protein interaction assays reveal that CRIF1 directly interacts with AR via the activation function-1 domain of AR. Interestingly, both the N-terminal and C-terminal half-regions of CRIF1 are independently capable of interacting with and repressing the transactivation of AR. CRIF1 represses AR transactivation through competition with AR coactivators. In addition, the CRIF1-mediated inhibition of AR transactivation involves the recruitment of histone deacetylase 4. Down-regulation of CRIF1 by small interfering RNA increases the transactivation of AR and the mRNA level of the AR target gene prostate-specific antigen, whereas the overexpression of CRIF1 decreases the prostate-specific antigen mRNA level. Finally, the overexpression of CRIF1 inhibits the androgen-induced proliferation and cell cycle progression of prostate cancer cells. Taken together, these results suggest that CRIF1 acts as an AR corepressor and may play an important role in the regulation of AR-positive growth of prostate cancer.


Assuntos
Proteínas de Ciclo Celular/metabolismo , Proteínas Nucleares/metabolismo , Receptores Androgênicos/metabolismo , Ativação Transcricional/genética , Animais , Northern Blotting , Western Blotting , Células COS , Ciclo Celular/genética , Proteínas de Ciclo Celular/genética , Linhagem Celular , Proliferação de Células , Chlorocebus aethiops , Imunoprecipitação da Cromatina , Citometria de Fluxo , Histona Desacetilases/genética , Histona Desacetilases/metabolismo , Humanos , Imunoprecipitação , Microscopia Confocal , Modelos Genéticos , Proteínas Nucleares/genética , Regiões Promotoras Genéticas/genética , Ligação Proteica , Receptores Androgênicos/genética , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo , Técnicas do Sistema de Duplo-Híbrido
18.
Diabetes ; 56(2): 431-7, 2007 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-17259388

RESUMO

Prolonged elevations of glucose concentration have deleterious effects on beta-cell function. One of the hallmarks of such glucotoxicity is a reduction in insulin gene expression, resulting from decreased insulin promoter activity. Small heterodimer partner (SHP; NR0B2) is an atypical orphan nuclear receptor that inhibits nuclear receptor signaling in diverse metabolic pathways. In this study, we found that sustained culture of INS-1 cells at high glucose concentrations leads to an increase in SHP mRNA expression, followed by a decrease in insulin gene expression. Inhibition of endogenous SHP gene expression by small interfering RNA partially restored high-glucose-induced suppression of the insulin gene. Adenovirus-mediated overexpression of SHP in INS-1 cells impaired glucose-stimulated insulin secretion as well as insulin gene expression. SHP downregulates insulin gene expression via two mechanisms: by downregulating PDX-1 and MafA gene expression and by inhibiting p300-mediated pancreatic duodenal homeobox factor 1-and BETA2-dependent transcriptional activity from the insulin promoter. Finally, the pancreatic islets of diabetic OLETF rats express SHP mRNA at higher levels than the islets from LETO rats. These results collectively suggest that SHP plays an important role in the development of beta-cell dysfunction induced by glucotoxicity.


Assuntos
Glucose/metabolismo , Proteínas de Homeodomínio/metabolismo , Células Secretoras de Insulina/metabolismo , Lectinas Tipo C/metabolismo , Glicoproteínas de Membrana/metabolismo , Receptores Citoplasmáticos e Nucleares/biossíntese , Transativadores/metabolismo , Animais , Linhagem Celular Tumoral , Regulação da Expressão Gênica/fisiologia , Insulina/genética , Insulinoma/metabolismo , Masculino , Neoplasias Pancreáticas/metabolismo , RNA Mensageiro/biossíntese , Ratos , Ratos Endogâmicos OLETF , Ratos Long-Evans , Ratos Sprague-Dawley , Receptores Citoplasmáticos e Nucleares/genética
19.
J Steroid Biochem Mol Biol ; 112(1-3): 117-21, 2008 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-18832037

RESUMO

We previously demonstrated that the expression of Mullerian inhibiting substance (MIS) in Sertoli cells is downregulated by tumor necrosis factor alpha (TNF-alpha), which is secreted by meiotic germ cells, in mouse testes. Several studies have reported that MIS that is secreted by Sertoli cells inhibits steroidogenesis and, thus, the synthesis of testosterone in testicular Leydig cells. Here, we demonstrate that in TNF-alpha knockout testes, which show high levels of MIS, steroidogenesis is decreased compared to that in wild-type testes. The levels of testosterone and the mRNA levels of steroidogenesis-related genes were significantly lower after puberty in TNF-alpha knockout testes than in wild-type testes. Furthermore, the number of sperm was reduced in TNF-alpha knockout mice. Histological analysis revealed that spermatogenesis is also delayed in TNF-alpha knockout testes. In conclusion, TNF-alpha knockout mice show reduced testicular steroidogenesis, which is likely due to the high level of testicular MIS compared to that seen in wild-type mice.


Assuntos
Células de Sertoli/fisiologia , Testículo/fisiologia , Testosterona/metabolismo , Fator de Necrose Tumoral alfa/fisiologia , Animais , Hormônio Antimülleriano/biossíntese , Masculino , Camundongos , Camundongos Knockout , Espermatogênese , Testículo/citologia , Fator de Necrose Tumoral alfa/genética
20.
Mol Cell Biol ; 25(12): 4841-52, 2005 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-15923603

RESUMO

The SWI3-related gene product (SRG3), a component of the mouse SWI/SNF complex, has been suggested to have an alternative function. Here, we demonstrate that in the prostate transactivation of the androgen receptor (AR) is modulated by SRG3 in multiple ways. The expression of SRG3, which is developmentally regulated in the prostate, is induced by androgen through AR. SRG3 in turn enhances the transactivation of AR, providing a positive feedback regulatory loop. The SRG3 coactivation of AR transactivation is achieved through the recruitment of coactivator SRC-1, the protein level of which is upregulated by SRG3, providing another pathway of positive regulation. Interestingly, SRG3 coactivation of AR transactivation is fully functional in BRG1/BRM-deficient C33A cells and the AR/SRG3/SRC-1 complex formed in vivo contains neither BRG1 nor BRM protein, suggesting the possibility of an SRG3 function independent of the SWI/SNF complex. Importantly, the AR/SRG3/SRC-1 complex occupies androgen response elements on the endogenous SRG3 and PSA promoter in an androgen-dependent manner in mouse prostate and LNCaP cells, respectively, inducing gene expression. These results suggest that the multiple positive regulatory mechanisms of AR transactivation by SRG3 may be important for the rapid proliferation of prostate cells during prostate development and regeneration.


Assuntos
Receptores Androgênicos/metabolismo , Fatores de Transcrição/metabolismo , Ativação Transcricional , Acetiltransferases/genética , Acetiltransferases/metabolismo , Animais , Proteínas de Ciclo Celular/genética , Proteínas de Ciclo Celular/metabolismo , Linhagem Celular , Histona Acetiltransferases , Humanos , Masculino , Camundongos , Camundongos Transgênicos , Coativador 1 de Receptor Nuclear , Coativadores de Receptor Nuclear , Proteínas Oncogênicas/genética , Proteínas Oncogênicas/metabolismo , Regiões Promotoras Genéticas , Próstata/citologia , Próstata/fisiologia , Ratos , Ratos Sprague-Dawley , Receptores Androgênicos/genética , Fatores de Transcrição/genética , Técnicas do Sistema de Duplo-Híbrido , Fatores de Transcrição de p300-CBP
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