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1.
PLoS One ; 15(9): e0237946, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32881925

RESUMO

Dietary fat is discussed to be critical in the development of non-alcoholic fatty liver disease. Here, we assess the effect of exchanging dietary fat source from butterfat to extra virgin olive oil on the progression of an already existing diet-induced non-alcoholic fatty liver disease in mice. Female C57BL/6J mice were fed a liquid butterfat-, fructose- and cholesterol-rich diet (BFC, 25E% from butterfat) or control diet (C, 12%E from soybean oil) for 13 weeks. In week 9, fat sources of some BFC- and C-fed mice were switched either to 25E% or 12E% olive oil (OFC and CO). Glucose and insulin tolerance tests were performed, and markers of liver damage and glucose metabolism were assessed. After 6 weeks of feeding, BFC-fed mice had developed marked signs of insulin resistance, which progressed to week 12 being not affected by the exchange of fat sources. Liver damage was similar between BFC- and OFC-fed mice. Markers of lipid metabolism and lipid peroxidation in liver and of insulin signaling in liver and muscle were also similarly altered in BFC- and OFC-fed mice. Taken together, our data suggest that exchanging butterfat with extra virgin olive oil has no effect on the progression of non-alcoholic fatty liver disease and glucose tolerance in mice.


Assuntos
Resistência à Insulina , Fígado/efeitos dos fármacos , Hepatopatia Gordurosa não Alcoólica/patologia , Azeite de Oliva/farmacologia , Animais , Peso Corporal/efeitos dos fármacos , Dieta Hiperlipídica , Progressão da Doença , Feminino , Glucose/metabolismo , Teste de Tolerância a Glucose , Insulina/metabolismo , Metabolismo dos Lipídeos/efeitos dos fármacos , Peroxidação de Lipídeos/efeitos dos fármacos , Fígado/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Hepatopatia Gordurosa não Alcoólica/veterinária , Receptor de Insulina/genética , Receptor de Insulina/metabolismo , Transdução de Sinais/efeitos dos fármacos
2.
Nat Struct Mol Biol ; 27(7): 615-624, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32483339

RESUMO

Human insulin and its current therapeutic analogs all show propensity, albeit varyingly, to self-associate into dimers and hexamers, which delays their onset of action and makes blood glucose management difficult for people with diabetes. Recently, we described a monomeric, insulin-like peptide in cone-snail venom with moderate human insulin-like bioactivity. Here, with insights from structural biology studies, we report the development of mini-Ins-a human des-octapeptide insulin analog-as a structurally minimal, full-potency insulin. Mini-Ins is monomeric and, despite the lack of the canonical B-chain C-terminal octapeptide, has similar receptor binding affinity to human insulin. Four mutations compensate for the lack of contacts normally made by the octapeptide. Mini-Ins also has similar in vitro insulin signaling and in vivo bioactivities to human insulin. The full bioactivity of mini-Ins demonstrates the dispensability of the PheB24-PheB25-TyrB26 aromatic triplet and opens a new direction for therapeutic insulin development.


Assuntos
Antígenos CD/química , Insulina/química , Venenos de Moluscos/química , Venenos de Moluscos/metabolismo , Receptor de Insulina/química , Substituição de Aminoácidos , Animais , Antígenos CD/metabolismo , Sítios de Ligação , Cristalografia por Raios X , Insulina/análogos & derivados , Insulina/metabolismo , Insulina/farmacologia , Camundongos Endogâmicos C57BL , Modelos Moleculares , Simulação de Dinâmica Molecular , Venenos de Moluscos/genética , Venenos de Moluscos/farmacologia , Peptídeos/química , Peptídeos/genética , Peptídeos/metabolismo , Conformação Proteica , Ratos Sprague-Dawley , Receptor de Insulina/metabolismo , Relação Estrutura-Atividade , Tirosina
3.
Hum Cell ; 33(4): 1204-1217, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32514738

RESUMO

Many reports have indicated that the insulin receptor (IR) causes tumorigenesis and the development of breast cancer. It has been considered a potential target for treating IR-related tumors. Traditionally, there are two categories of insulin receptor (IR) antagonists, they are small molecule antagonists and anti-IR antibodies. Here, we describe a new method (anti-idiotypic antibody strategy) for the development of IR antagonist. Hybridoma technology was employed to design and identify a series of anti-idiotypic antibodies against insulin. After repeated screening and identification, an anti-idiotypic antibody against IR (AK98) was obtained. Analysis through competitive ELISA and competitive receptor binding indicated that AK98 mimicked the receptor binding epitope of insulin. The interaction between AK98 and IR was determined using indirect immunofluorescence, immunoelectron microscopy, and Immunoprecipitation-Western (IP-WB). Further research using a tumor cell model revealed that AK98 inhibited insulin-IR binding and IR-mediated intracellular signaling pathways. Conclusively, the main purpose of this paper is that we proposed a new method (anti-idiotypic antibody strategy) to develop the insulin receptor (IR) antagonist (AK98), and a series of experiments showed that the anti-idiotypic antibody (AK98) exhibited good antagonistic activity against IR. This work suggests that the anti-idiotypic antibody may be a potential strategy to develop IR antagonists that can be used in treating breast cancer.


Assuntos
Anticorpos Anti-Idiotípicos , Antineoplásicos , Neoplasias da Mama/tratamento farmacológico , Neoplasias da Mama/patologia , Desenvolvimento de Medicamentos/instrumentação , Desenvolvimento de Medicamentos/métodos , Receptor de Insulina/antagonistas & inibidores , Anticorpos Anti-Idiotípicos/farmacologia , Anticorpos Anti-Idiotípicos/uso terapêutico , Antineoplásicos/farmacologia , Antineoplásicos/uso terapêutico , Feminino , Humanos , Hibridomas , Insulina/metabolismo , Células MCF-7 , Ligação Proteica/efeitos dos fármacos , Receptor de Insulina/metabolismo , Transdução de Sinais/efeitos dos fármacos , Transdução de Sinais/genética
4.
Nat Commun ; 11(1): 2983, 2020 06 12.
Artigo em Inglês | MEDLINE | ID: mdl-32532993

RESUMO

Calorimetry has been widely used in metabolic studies, but direct measurements from individual small biological model organisms such as C. elegans or isolated single cells have been limited by poor sensitivity of existing techniques and difficulties in resolving very small heat outputs. Here, by careful thermal engineering, we developed a robust, highly sensitive and bio-compatible calorimetric platform that features a resolution of ~270 pW-more than a 500-fold improvement over the most sensitive calorimeter previously used for measuring the metabolic heat output of C. elegans. Using this calorimeter, we demonstrate time-resolved metabolic measurements of single C. elegans worms from larval to adult stages. Further, we show that the metabolic output is significantly lower in long-lived C. elegans daf-2 mutants. These demonstrations clearly highlight the broad potential of this tool for studying the role of metabolism in disease, development and aging of small model organisms and single cells.


Assuntos
Caenorhabditis elegans/metabolismo , Calorimetria/métodos , Análise de Célula Única/métodos , Temperatura , Animais , Metabolismo Basal/genética , Caenorhabditis elegans/citologia , Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/genética , Proteínas de Caenorhabditis elegans/metabolismo , Calorimetria/instrumentação , Metabolismo Energético/genética , Humanos , Larva/citologia , Larva/genética , Larva/metabolismo , Longevidade/genética , Modelos Animais , Mutação , Receptor de Insulina/genética , Receptor de Insulina/metabolismo , Reprodutibilidade dos Testes , Análise de Célula Única/instrumentação , Condutividade Térmica
5.
Life Sci ; 256: 117910, 2020 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-32504753

RESUMO

AIMS: Insulin (Ins) covalently modified by catecholestrogens (CEs) was commonly found in diabetic patients who have developed insulin resistance. Estrogenization of insulin altered its molecular function and effect carbohydrates metabolisms in these patients. Insulin resistance is a common phenomenon in diabetes but the exact mechanism remains unknown. In this study, binding specificity and affinity of autoantibodies against estrogenized insulin (4-hydroxyestradiol-insulin; 4-OHE2-Ins) were assayed in the serum of type 1 diabetes (T1D) patients in order to explain the phenomena behind insulin resistance. MATERIALS AND METHODS: Specificity and affinity of autoantibodies from the sera of 66 T1D patients and 41 controls were analyzed by direct binding, competition ELISA and quantitative precipitin titration. Insulin was also estimated in the serum of T1D patients by ELISA. KEY FINDING: Estrogenized insulin (4-OHE2-Ins) exhibited high affinity and specificity to T1D autoantibodies in comparison to Ins (p < .05) or 4-OHE2 (p < .001). Estrogenization of insulin alters its interaction with the insulin receptor (IR). The affinity constant of 4-OHE2-Ins with the T1D autoantibodies was found to be 1.41 × 10-7 M. SIGNIFICANCE: Estrogenization of insulin by catecholestrogen makes these molecules highly antigenic and produced high-affinity autoantibodies in T1D patients. As a result, patients develop insulin resistance and presented this molecule as a potential biomarker for T1D.


Assuntos
Autoanticorpos/imunologia , Diabetes Mellitus Tipo 1/tratamento farmacológico , Estrogênios de Catecol/química , Hipoglicemiantes/química , Insulina/química , Adulto , Autoanticorpos/metabolismo , Biomarcadores/metabolismo , Glicemia/análise , Coleta de Amostras Sanguíneas , Proposta de Concorrência , Ensaio de Imunoadsorção Enzimática , Estrogênios de Catecol/uso terapêutico , Feminino , Humanos , Hipoglicemiantes/uso terapêutico , Insulina/uso terapêutico , Resistência à Insulina , Masculino , Pessoa de Meia-Idade , Receptor de Insulina/imunologia , Receptor de Insulina/metabolismo , Sensibilidade e Especificidade
6.
Chemosphere ; 256: 127172, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32470744

RESUMO

Nanoplastic exposure could cause toxicity to Caenorhabditis elegans at various aspects. Nevertheless, the effects of chronic exposure to nanoplastics remain largely unclear in nematodes. In this study, we employed C. elegans as an animal model to determine the effects of nanopolystyrene (30 nm) exposure from adult day-1 for 8-day. After the exposure, only 1000 µg/L nanopolystyrene reduced the lifespan. In contrast, nanopolystyrene ≥1 µg/L decreased locomotion behavior and activated oxidative stress. Meanwhile, in 10 µg/L nanopolystyrene exposed nematodes, both expression of SOD-3, a Mn-SOD, and autophagy induction as indicated by LGG-1:GFP expression were significantly increased. RNAi knockdown of daf-2 encoding an insulin receptor enhanced the autophagy induction, and RNAi knockdown of daf-16 encoding a FOXO transcriptional factor in insulin signaling pathway suppressed the autophagy induction in 10 µg/L nanopolystyrene exposed nematodes. Moreover, DAF-16 acted upstream of LGG-1, an ortholog of Atg8/LC3, to regulate the toxicity of nanopolystyrene toxicity in inducing ROS production and in decreasing locomotion behavior at adult day-9. Our data implied the potential toxicity of chronic exposure to nanoplastics at predicted environmental concentrations on organisms.


Assuntos
Autofagia/efeitos dos fármacos , Caenorhabditis elegans/efeitos dos fármacos , Locomoção/efeitos dos fármacos , Estresse Oxidativo/efeitos dos fármacos , Poliestirenos/toxicidade , Animais , Proteínas de Caenorhabditis elegans/biossíntese , Proteínas de Caenorhabditis elegans/genética , Fatores de Transcrição Forkhead/genética , Insulina/metabolismo , Locomoção/genética , Longevidade , Modelos Animais , Interferência de RNA , Receptor de Insulina/genética , Receptor de Insulina/metabolismo , Transdução de Sinais , Superóxido Dismutase/biossíntese
7.
J Med Chem ; 63(11): 6134-6143, 2020 06 11.
Artigo em Inglês | MEDLINE | ID: mdl-32406685

RESUMO

Native insulin is susceptible to biophysical aggregation and fibril formation, promoted by manual agitation and elevated temperatures. The safety of the drug and its application to alternative forms of administration could be enhanced through the identification of chemical modifications that strengthen its physical stability without compromising its biological properties. Complex polysialic acids (PSAs) exist naturally and provide a means to enhance the physical properties of peptide therapeutics. A set of insulin analogues site-specifically derivatized with sialic acid were prepared in an overall yield of 50-60%. Addition of a single or multiple sialic acids conferred remarkable enhancement to the biophysical stability of human insulin while maintaining its potency. The time to the onset of fibrillation was extended by more than 10-fold relative to that of the native hormone. These results demonstrate that simplified sialic acid conjugates represent a viable alternative to complex natural PSAs in increasing the stability of therapeutic peptides.


Assuntos
Insulina/análogos & derivados , Ácido N-Acetilneuramínico/química , Animais , Glicemia/análise , Diabetes Mellitus Experimental/induzido quimicamente , Diabetes Mellitus Experimental/tratamento farmacológico , Células HEK293 , Humanos , Insulina/farmacocinética , Insulina/uso terapêutico , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Oligopeptídeos/síntese química , Oligopeptídeos/química , Receptor de Insulina/genética , Receptor de Insulina/metabolismo , Ácidos Siálicos/química , Equivalência Terapêutica
8.
Nat Commun ; 11(1): 2080, 2020 04 29.
Artigo em Inglês | MEDLINE | ID: mdl-32350271

RESUMO

Excessive insulin signaling through the insulin receptor (IR) may play a role in the pathogenesis of diet-induced metabolic disease, including obesity and type 2 diabetes. Here we investigate whether heterozygous impairment of insulin receptor (IR) expression limited to peripheral, i.e. non-CNS, tissues of adult mice impacts the development of high-fat diet-induced metabolic deterioration. While exhibiting some features of insulin resistance, PerIRKO+/- mice display a hepatic energy deficit accompanied by induction of energy-sensing AMPK, mitochondrial biogenesis, PPARα, unexpectedly leading to protection from, and reversal of hepatic lipid accumulation (steatosis hepatis, NAFLD). Consistently, and unlike in control mice, the PPARα activator fenofibrate fails to further affect hepatic lipid accumulation in PerIRKO+/- mice. Taken together, and opposing previously established diabetogenic features of insulin resistance, incomplete impairment of insulin signaling may mimic central aspects of calorie restriction to limit hepatic lipid accumulation during conditions of metabolic stress.


Assuntos
Dieta Hiperlipídica/efeitos adversos , Jejum/metabolismo , Fígado Gorduroso/etiologia , Fígado Gorduroso/prevenção & controle , Receptor de Insulina/metabolismo , Animais , Composição Corporal , Metabolismo Energético , Comportamento Alimentar , Glucose/metabolismo , Homeostase , Resistência à Insulina , Fígado/metabolismo , Fígado/patologia , Masculino , Camundongos Endogâmicos C57BL , Camundongos Knockout
9.
Am J Chin Med ; 48(4): 1005-1019, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32468825

RESUMO

Harboring insulin-producing cells, the pancreas has more interstitial insulin than any other organ. In vitro, insulin activates both insulin receptor (IR) and insulin-like growth factor-1 receptor (IGF1R) to stimulate pancreatic cancer cells. Whether intra-pancreatic insulin nourishes pancreatic cancer cells in vivo remains uncertain. In the present studies, we transplanted human pancreatic cancer cells orthotopically in euglycemic athymic mice whose intra-pancreatic insulin was intact or was decreased following pretreatment with streptozotocin (STZ). In the next eight weeks, the tumor carriers were treated with one of the IR/IGF1R antagonists penta-O-galloyl-[Formula: see text]-D-glucose (PGG) and epigallocatechin gallate (EGCG) or treated with vehicle. When pancreatic tumors were examined, their fraction occupied with living cells was decreased following STZ pretreatment and/or IR/IGF1R antagonism. Using Western blot, we examined tumor grafts for IR/IGF1R expression and activity. We also determined proteins that were downstream to IR/IGF1R and responsible for signal transduction, glycolysis, angiogenesis, and apoptosis. We demonstrated that STZ-induced decrease in intra-pancreatic insulin reduced IR/IGF1R expression and activity, decreased the proteins that promoted cell survival, and increased the proteins that promoted apoptosis. These suggest that intra-pancreatic insulin supported local cancer cells. When tumor carriers were treated with PGG or EGCG, the results were similar to those seen following STZ pretreatment. Thus, the biggest changes in examined proteins were usually seen when STZ pretreatment and PGG/EGCG treatment concurred. This suggests that intra-pancreatic insulin normally combated pharmacologic effects of PGG and EGCG. In conclusion, intra-pancreatic insulin nourishes pancreatic cancer cells and helps the cells resist IR/IGF1R antagonism.


Assuntos
Catequina/análogos & derivados , Taninos Hidrolisáveis/farmacologia , Insulina/fisiologia , Neoplasias Pancreáticas/patologia , Receptor de Insulina/antagonistas & inibidores , Animais , Catequina/farmacologia , Linhagem Celular Tumoral , Expressão Gênica/efeitos dos fármacos , Humanos , Insulina/metabolismo , Fator de Crescimento Insulin-Like I/genética , Fator de Crescimento Insulin-Like I/metabolismo , Masculino , Camundongos Nus , Receptor de Insulina/genética , Receptor de Insulina/metabolismo , Estreptozocina/farmacologia
10.
Chemosphere ; 253: 126772, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32464760

RESUMO

Zeranol is an approved but controversial growth-promoting agent for livestock in North America. It is a mycotoxin metabolite secreted by the Fusarium family fungi. The regulatory bodies in this region have established the acceptable daily intake and exposure below the level would not significantly increase the health risk for humans. However, their European counterparts have yet to establish an acceptable level and do not permit the use of this agent in farm animals. Given the growth-promoting ability of zeranol, its effect on energy metabolism was investigated in the current study. Our results indicated that zeranol could induce glucose transporter type 4 (GLUT4) expression in 3T3 L1 cells at 10 µM and initiate the translocation of the glucose transporter to the membrane as assayed by confocal microscopy. The translocation was likely triggered by the increase of GLUT4 and p-Akt. The insulin signal transduction pathway of glucose translocation was analyzed by Western blot analysis. Since no increase in the phosphorylated insulin receptor substrate in zeranol-treated cells was evidenced, the increased p-Akt and GLUT4 amount should be the mechanism dictating the GLUT4 translocation. In summary, this study showed that zeranol could perturb glucose metabolism in differentiated 3T3 L1 adipocytes. Determining the growth-promoting mechanism is crucial to uncover an accepted alternative to the general public.


Assuntos
Transportador de Glucose Tipo 4/metabolismo , Reguladores de Crescimento de Planta/toxicidade , Zeranol/toxicidade , Células 3T3-L1 , Adipócitos , Animais , Antígenos CD , Metabolismo dos Carboidratos , Glucose/metabolismo , Insulina/metabolismo , Gado , Camundongos , América do Norte , Fosforilação , Receptor de Insulina/metabolismo , Transdução de Sinais/efeitos dos fármacos
11.
Am J Physiol Renal Physiol ; 318(6): F1441-F1453, 2020 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-32390512

RESUMO

Carbonic anhydrase II knockout (Car2-/-) mice have depleted numbers of renal intercalated cells, which are increasingly recognized to be innate immune effectors. We compared pyelonephritis susceptibility following reciprocal renal transplantations between Car2-/- and wild-type mice. We examined the effect of pharmacological CA suppression using acetazolamide in an experimental murine model of urinary tract infection. Car2-/- versus wild-type mice were compared for differences in renal innate immunity. In our transplant scheme, mice lacking CA-II in the kidney had increased pyelonephritis risk. Mice treated with acetazolamide had lower kidney bacterial burdens at 6 h postinfection, which appeared to be due to tubular flow from diuresis because comparable results were obtained when furosemide was substituted for acetazolamide. Isolated Car2-/- kidney cells enriched for intercalated cells demonstrated altered intercalated cell innate immune gene expression, notably increased calgizzarin and insulin receptor expression. Intercalated cell number and function along with renal tubular flow are determinants of pyelonephritis risk.


Assuntos
Acetazolamida/farmacologia , Anidrase Carbônica II/deficiência , Inibidores da Anidrase Carbônica/farmacologia , Infecções por Escherichia coli/prevenção & controle , Rim/efeitos dos fármacos , Pielonefrite/prevenção & controle , Infecções Urinárias/prevenção & controle , Acidose/enzimologia , Acidose/genética , Animais , Anidrase Carbônica II/antagonistas & inibidores , Anidrase Carbônica II/genética , Modelos Animais de Doenças , Infecções por Escherichia coli/enzimologia , Infecções por Escherichia coli/genética , Infecções por Escherichia coli/microbiologia , Regulação da Expressão Gênica no Desenvolvimento , Predisposição Genética para Doença , Imunidade Inata , Rim/enzimologia , Rim/imunologia , Rim/microbiologia , Transplante de Rim , Camundongos Endogâmicos C57BL , Camundongos Knockout , Pielonefrite/enzimologia , Pielonefrite/genética , Pielonefrite/microbiologia , Receptor de Insulina/genética , Receptor de Insulina/metabolismo , Proteínas S100/genética , Proteínas S100/metabolismo , Infecções Urinárias/enzimologia , Infecções Urinárias/genética , Infecções Urinárias/microbiologia , Escherichia coli Uropatogênica/patogenicidade
12.
Breast Cancer Res ; 22(1): 40, 2020 05 12.
Artigo em Inglês | MEDLINE | ID: mdl-32393319

RESUMO

BACKGROUND: Racial disparities in breast cancer survival between Black and White women persist across all stages of breast cancer. The metabolic syndrome (MetS) of insulin resistance disproportionately affects more Black than White women. It has not been discerned if insulin resistance mediates the link between race and poor prognosis in breast cancer. We aimed to determine whether insulin resistance mediates in part the association between race and breast cancer prognosis, and if insulin receptor (IR) and insulin-like growth factor receptor (IGF-1R) expression differs between tumors from Black and White women. METHODS: We conducted a cross-sectional, multi-center study across ten hospitals. Self-identified Black women and White women with newly diagnosed invasive breast cancer were recruited. The primary outcome was to determine if insulin resistance, which was calculated using the homeostatic model assessment of insulin resistance (HOMA-IR), mediated the effect of race on prognosis using the multivariate linear mediation model. Demographic data, anthropometric measurements, and fasting blood were collected. Poor prognosis was defined as a Nottingham Prognostic Index (NPI) > 4.4. Breast cancer pathology specimens were evaluated for IR and IGF-1R expression by immunohistochemistry (IHC). RESULTS: Five hundred fifteen women were recruited (83% White, 17% Black). The MetS was more prevalent in Black women than in White women (40% vs 20%, p < 0.0001). HOMA-IR was higher in Black women than in White women (1.9 ± 1.2 vs 1.3 ± 1.4, p = 0.0005). Poor breast cancer prognosis was more prevalent in Black women than in White women (28% vs 15%. p = 0.004). HOMA-IR was positively associated with NPI score (r = 0.1, p = 0.02). The mediation model, adjusted for age, revealed that HOMA-IR significantly mediated the association between Black race and poor prognosis (ß = 0.04, 95% CI 0.005-0.009, p = 0.002). IR expression was higher in tumors from Black women than in those from White women (79% vs 52%, p = 0.004), and greater IR/IGF-1R ratio was also associated with higher NPI score (IR/IGF-1R >  1: 4.2 ± 0.8 vs IR/IGF-1R = 1: 3.9 ± 0.8 vs IR/IGF-1R < 1: 3.5 ± 1.0, p < 0.0001). CONCLUSIONS: In this multi-center, cross-sectional study of US women with newly diagnosed invasive breast cancer, insulin resistance is one factor mediating part of the association between race and poor prognosis in breast cancer.


Assuntos
Afro-Americanos/estatística & dados numéricos , Neoplasias da Mama/epidemiologia , Neoplasias da Mama/patologia , Grupo com Ancestrais do Continente Europeu/estatística & dados numéricos , Disparidades em Assistência à Saúde/estatística & dados numéricos , Resistência à Insulina , Neoplasias da Mama/metabolismo , Estudos Transversais , Feminino , Humanos , Pessoa de Meia-Idade , Gradação de Tumores , Estadiamento de Neoplasias , Prognóstico , Receptor IGF Tipo 1/metabolismo , Receptor de Insulina/metabolismo , Estados Unidos/epidemiologia
13.
Nat Commun ; 11(1): 2024, 2020 04 24.
Artigo em Inglês | MEDLINE | ID: mdl-32332780

RESUMO

Crosstalk between liver and skeletal muscle is vital for glucose homeostasis. Hepatokines, liver-derived proteins that play an important role in regulating muscle metabolism, are important to this communication. Here we identify apolipoprotein J (ApoJ) as a novel hepatokine targeting muscle glucose metabolism and insulin sensitivity through a low-density lipoprotein receptor-related protein-2 (LRP2)-dependent mechanism, coupled with the insulin receptor (IR) signaling cascade. In muscle, LRP2 is necessary for insulin-dependent IR internalization, an initial trigger for insulin signaling, that is crucial in regulating downstream signaling and glucose uptake. Of physiologic significance, deletion of hepatic ApoJ or muscle LRP2 causes insulin resistance and glucose intolerance. In patients with polycystic ovary syndrome and insulin resistance, pioglitazone-induced improvement of insulin action is associated with an increase in muscle ApoJ and LRP2 expression. Thus, the ApoJ-LRP2 axis is a novel endocrine circuit that is central to the maintenance of normal glucose homeostasis and insulin sensitivity.


Assuntos
Clusterina/metabolismo , Glucose/metabolismo , Resistência à Insulina , Músculo Esquelético/metabolismo , Síndrome do Ovário Policístico/metabolismo , Adulto , Animais , Linhagem Celular , Clusterina/sangue , Clusterina/genética , Modelos Animais de Doenças , Feminino , Técnica Clamp de Glucose , Humanos , Hipoglicemiantes/farmacologia , Hipoglicemiantes/uso terapêutico , Insulina/metabolismo , Fígado/metabolismo , Proteína-2 Relacionada a Receptor de Lipoproteína de Baixa Densidade/genética , Proteína-2 Relacionada a Receptor de Lipoproteína de Baixa Densidade/metabolismo , Masculino , Camundongos , Camundongos Knockout , Pioglitazona/farmacologia , Pioglitazona/uso terapêutico , Síndrome do Ovário Policístico/sangue , Síndrome do Ovário Policístico/tratamento farmacológico , Receptor de Insulina/metabolismo , Transdução de Sinais/efeitos dos fármacos
14.
Am J Physiol Regul Integr Comp Physiol ; 318(6): R1078-R1090, 2020 06 01.
Artigo em Inglês | MEDLINE | ID: mdl-32348681

RESUMO

Cx30.2 protein content and localization were assessed during development. An account of Cx30.2, Cx43, Cx46, and Cx50, and insulin receptor (IR) responses to Cx30.2, Cx46, or Cx50 deficiency in mouse interstitial tissue (ITf)- and seminiferous tubule-enriched fractions (STf) is given. The impact of high glucose/insulin on Cx30.2 was investigated in spontaneously diabetic and obese db/db and ob/ob mouse testis and anterior pituitary (AP). Cx30.2 labeled contacts in vascular endothelial and Leydig cells and Sertoli cell junctions in stage V-VII. Cx30.2 expression is regulated differently in the interstitium and tubules. Cx30.2 at 30-kDa levels peaked by 28 days in ITf and by 14 days in STf. In STf, deleting Cx30.2 decreased Cx43 and Cx50, whereas deleting Cx50 downregulated Cx30.2. The opposite occurred in ITf. In STf, deleting Cx30.2 upregulated Cx46 except the full-length reciprocally, deleting Cx46 upregulated Cx30.2. In ITf, Cx30.2 deficiency upregulated full-length and phosphorylated Cx46, whereas deleting Cx46 downregulated 48- to 50-kDa Cx30.2. The db/db and ob/ob mouse ITf, STf, and AP showed imbalanced Cx30.2 levels. IRα levels at 135 kDa declined in Cx30.2-/- and Cx50-/- mouse ITf and Cx46-/- and Cx50-/- STf. IRß at 98 to 110 kDa dropped in Cx30.2-/- and Cx46-/- mice STf suggesting that Cx30.2 deficiency decreases active IR sites. The results show the connexins interdependence and interaction and that altering a single connexin changes the remaining connexins expression, which can modify gap junction-mediated glucose exchanges in contacting cells. Data suggest that glucose/insulin influences Cx30.2 turnover in testis and AP and, reciprocally, that connexins modulate testis glucose uptake and response to insulin.


Assuntos
Conexina 43/genética , Conexinas/genética , Diabetes Mellitus Experimental/genética , Obesidade/genética , Receptor de Insulina/genética , Testículo/metabolismo , Animais , Conexina 43/metabolismo , Conexinas/metabolismo , Diabetes Mellitus Experimental/metabolismo , Regulação da Expressão Gênica , Masculino , Camundongos , Camundongos Knockout , Obesidade/metabolismo , Receptor de Insulina/metabolismo
15.
Proc Natl Acad Sci U S A ; 117(17): 9292-9301, 2020 04 28.
Artigo em Inglês | MEDLINE | ID: mdl-32277029

RESUMO

In insects, 20-hydroxyecdysone (20E) limits the growth period by triggering developmental transitions; 20E also modulates the growth rate by antagonizing insulin/insulin-like growth factor signaling (IIS). Previous work has shown that 20E cross-talks with IIS, but the underlying molecular mechanisms are not fully understood. Here we found that, in both the silkworm Bombyx mori and the fruit fly Drosophila melanogaster, 20E antagonized IIS through the AMP-activated protein kinase (AMPK)-protein phosphatase 2A (PP2A) axis in the fat body and suppressed the growth rate. During Bombyx larval molt or Drosophila pupariation, high levels of 20E activate AMPK, a molecular sensor that maintains energy homeostasis in the insect fat body. In turn, AMPK activates PP2A, which further dephosphorylates insulin receptor and protein kinase B (AKT), thus inhibiting IIS. Activation of the AMPK-PP2A axis and inhibition of IIS in the Drosophila fat body reduced food consumption, resulting in the restriction of growth rate and body weight. Overall, our study revealed an important mechanism by which 20E antagonizes IIS in the insect fat body to restrict the larval growth rate, thereby expanding our understanding of the comprehensive regulatory mechanisms of final body size in animals.


Assuntos
Proteínas Quinases Ativadas por AMP/metabolismo , Tamanho Corporal/fisiologia , Proteína Fosfatase 2/metabolismo , Animais , Bombyx/crescimento & desenvolvimento , Bombyx/metabolismo , Drosophila/crescimento & desenvolvimento , Drosophila/metabolismo , Ecdisterona/metabolismo , Corpo Adiposo/metabolismo , Regulação da Expressão Gênica no Desenvolvimento/efeitos dos fármacos , Proteínas de Insetos/genética , Insetos/crescimento & desenvolvimento , Insetos/metabolismo , Insulina/metabolismo , Larva/crescimento & desenvolvimento , Receptor de Insulina/metabolismo , Transdução de Sinais/efeitos dos fármacos , Somatomedinas/metabolismo
16.
Am J Physiol Endocrinol Metab ; 318(5): E791-E805, 2020 05 01.
Artigo em Inglês | MEDLINE | ID: mdl-32182124

RESUMO

Irisin, a newly identified myokine, is critical to modulating body metabolism and biological homeostasis. However, whether irisin protects the skeletal muscles against metabolic stresses remains unknown. In this study, we determine the effect of irisin on high glucose and fatty acid-induced damages using irisin-overexpressed mouse C2C12 (irisin-C2C12) myoblasts and skeletal muscle from irisin-injected mice. Compared with empty vector-transfected control C2C12 cells, irisin overexpression resulted in a marked increase in cell viability and decrease in apoptosis under high-glucose stress. Progression of the cell cycle into the G2/M phase in the proliferative condition was also observed with irisin overexpression. Furthermore, glucose uptake, glycogen accumulation, and phosphorylation of AMPKα/insulin receptor (IR) ß-subunit/Erk1/2 in response to insulin stimulation were enhanced by irisin overexpression. In irisin-C2C12 myoblasts, these responses of phosphorylation were preserved under palmitate treatment, which induced insulin resistance in the control cells. These effects of irisin were reversed by inhibiting AMPK with compound C. In addition, high glucose-induced suppression of the mitochondrial membrane potential was also prevented by irisin. Moreover, suppression of IR in irisin-C2C12 myoblasts by cotransfection of shRNA against IR also mitigated the effects of irisin while not affecting AMPKα phosphorylation. As an in vivo study, soleus muscles from irisin-injected mice showed elevated phosphorylation of AMPKα and Erk1/2 and glycogen contents. Our results indicate that irisin counteracts the stresses generated by high glucose and fatty acid levels and irisin overexpression serves as a novel approach to elicit cellular protection. Furthermore, AMPK activation is a crucial factor that regulates insulin action as a downstream target.


Assuntos
Adenilato Quinase/metabolismo , Fibronectinas/farmacologia , Glucose/farmacologia , Mioblastos/efeitos dos fármacos , Ácido Palmítico/farmacologia , Receptor de Insulina/metabolismo , Transdução de Sinais/efeitos dos fármacos , Animais , Fibronectinas/genética , Fibronectinas/metabolismo , Resistência à Insulina/fisiologia , Camundongos , Mioblastos/metabolismo , Fosforilação/efeitos dos fármacos , Transdução de Sinais/fisiologia
17.
Life Sci ; 249: 117540, 2020 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-32165212

RESUMO

Alzheimer's disease, a progressive neurodegenerative disorder, is one of the leading causes of death in the USA, along with cancer and cardiac disorders. AD is characterized by various neurological factors like amyloid plaques, tau hyperphosphorylation, mitochondrial dysfunction, acetylcholine deficiency, etc. Together, impaired insulin signaling in the brain is also observed as essential factor to be considered in AD pathophysiology. Hence, currently researchers focused on studying the effect of brain insulin metabolism and relation of diabetes with AD. Based on the investigations, AD is also considered as type 3 or brain diabetes. Besides the traditional view of correlating AD with aging, a better understanding of various pathological factors and effects of other physical ailments is necessary to develop a promising therapeutic approach. There is a vast scope of studying the relation of systemic insulin level, insulin signaling, its neuroprotective potency and effect of diabetes on AD progression. The present work describes worldwide status of AD and its relation with diabetes mellitus and insulin metabolism; pathophysiology of AD; different metabolic pathways associating insulin metabolism with AD; insulin receptor and signaling in the brain; glucose metabolism; insulin resistance; and various preclinical and clinical studies reported insulin-based therapies to treat AD via systemic route and through direct intranasal delivery to the brain.


Assuntos
Doença de Alzheimer/tratamento farmacológico , Insulina/uso terapêutico , Doença de Alzheimer/metabolismo , Doença de Alzheimer/patologia , Animais , Progressão da Doença , Humanos , Insulina/metabolismo , Estresse Oxidativo , Receptor de Insulina/metabolismo , Transdução de Sinais
18.
Nat Commun ; 11(1): 1381, 2020 03 13.
Artigo em Inglês | MEDLINE | ID: mdl-32170063

RESUMO

Signaling through the insulin receptor governs central physiological functions related to cell growth and metabolism. Here we show by tandem native protein complex purification approach and super-resolution STED microscopy that insulin receptor activity requires association with the fundamental structural module in muscle, the dystrophin glycoprotein complex (DGC), and the desmosomal component plakoglobin (γ-catenin). The integrity of this high-molecular-mass assembly renders skeletal muscle susceptibility to insulin, because DGC-insulin receptor dissociation by plakoglobin downregulation reduces insulin signaling and causes atrophy. Furthermore, low insulin receptor activity in muscles from transgenic or fasted mice decreases plakoglobin-DGC-insulin receptor content on the plasma membrane, but not when plakoglobin is overexpressed. By masking ß-dystroglycan LIR domains, plakoglobin prevents autophagic clearance of plakoglobin-DGC-insulin receptor co-assemblies and maintains their function. Our findings establish DGC as a signaling hub, and provide a possible mechanism for the insulin resistance in Duchenne Muscular Dystrophy, and for the cardiomyopathies seen with plakoglobin mutations.


Assuntos
Distrofina/metabolismo , Glicoproteínas/metabolismo , Músculo Esquelético/metabolismo , Receptor de Insulina/metabolismo , Transdução de Sinais , gama Catenina/metabolismo , Animais , Autofagia , Membrana Celular/metabolismo , Modelos Animais de Doenças , Distroglicanas/metabolismo , Distrofina/genética , Masculino , Camundongos , Camundongos Transgênicos , Distrofia Muscular de Duchenne/metabolismo , Domínios Proteicos
19.
J Biol Chem ; 295(10): 3080-3098, 2020 03 06.
Artigo em Inglês | MEDLINE | ID: mdl-32005662

RESUMO

Globular protein sequences encode not only functional structures (the native state) but also protein foldability, i.e. a conformational search that is both efficient and robustly minimizes misfolding. Studies of mutations associated with toxic misfolding have yielded insights into molecular determinants of protein foldability. Of particular interest are residues that are conserved yet dispensable in the native state. Here, we exploited the mutant proinsulin syndrome (a major cause of permanent neonatal-onset diabetes mellitus) to investigate whether toxic misfolding poses an evolutionary constraint. Our experiments focused on an invariant aromatic motif (PheB24-PheB25-TyrB26) with complementary roles in native self-assembly and receptor binding. A novel class of mutations provided evidence that insulin can bind to the insulin receptor (IR) in two different modes, distinguished by a "register shift" in this motif, as visualized by molecular dynamics (MD) simulations. Register-shift variants are active but defective in cellular foldability and exquisitely susceptible to fibrillation in vitro Indeed, expression of the corresponding proinsulin variant induced endoplasmic reticulum stress, a general feature of the mutant proinsulin syndrome. Although not present among vertebrate insulin and insulin-like sequences, a prototypical variant ([GlyB24]insulin) was as potent as WT insulin in a rat model of diabetes. Although in MD simulations the shifted register of receptor engagement is compatible with the structure and allosteric reorganization of the IR-signaling complex, our results suggest that this binding mode is associated with toxic misfolding and so is disallowed in evolution. The implicit threat of proteotoxicity limits sequence variation among vertebrate insulins and insulin-like growth factors.


Assuntos
Evolução Molecular , Insulina/análogos & derivados , Motivos de Aminoácidos , Animais , Sítios de Ligação , Glicemia/análise , Diabetes Mellitus Experimental/tratamento farmacológico , Diabetes Mellitus Experimental/metabolismo , Diabetes Mellitus Experimental/patologia , Células HEK293 , Humanos , Insulina/metabolismo , Insulina/uso terapêutico , Simulação de Dinâmica Molecular , Ligação Proteica , Dobramento de Proteína , Estabilidade Proteica , Ratos , Receptor de Insulina/metabolismo , Relação Estrutura-Atividade , Termodinâmica
20.
Int J Mol Sci ; 21(3)2020 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-32046161

RESUMO

Dexamethasone (Dex) has been widely used as a potent anti-inflammatory, antishock, and immunosuppressive agent. However, high dose or long-term use of Dex is accompanied by side effects including skeletal muscle atrophy, whose underlying mechanisms remain incompletely understood. A number of microRNAs (miRNAs) have been shown to play key roles in skeletal muscle atrophy. Previous studies showed significantly increased miR-322 expression in Dex-treated C2C12 myotubes. In our study, the glucocorticoid receptor (GR) was required for Dex to increase miR-322 expression in C2C12 myotubes. miR-322 mimic or miR-322 inhibitor was used for regulating the expression of miR-322. Insulin-like growth factor 1 receptor (IGF1R) and insulin receptor (INSR) were identified as target genes of miR-322 using luciferase reporter assays and played key roles in Dex-induced muscle atrophy. miR-322 overexpression promoted atrophy in Dex-treated C2C12 myotubes and the gastrocnemius muscles of mice. Conversely, miR-322 inhibition showed the opposite effects. These data suggested that miR-322 contributes to Dex-induced muscle atrophy via targeting of IGF1R and INSR. Furthermore, miR-322 might be a potential target to counter Dex-induced muscle atrophy. miR-322 inhibition might also represent a therapeutic approach for Dex-induced muscle atrophy.


Assuntos
MicroRNAs/genética , Fibras Musculares Esqueléticas/metabolismo , Atrofia Muscular/metabolismo , Receptor IGF Tipo 1/genética , Receptor de Insulina/genética , Animais , Linhagem Celular , Dexametasona/toxicidade , Masculino , Camundongos , Camundongos Endogâmicos C57BL , MicroRNAs/metabolismo , Fibras Musculares Esqueléticas/efeitos dos fármacos , Atrofia Muscular/etiologia , Atrofia Muscular/genética , Receptor IGF Tipo 1/metabolismo , Receptor de Insulina/metabolismo
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