RESUMO
Phosphofructokinase (PFK) is a key regulatory enzyme of glycolysis, being considered the pacemaker of this pathway. In mammals, this enzyme exists as three different isoforms, PFKM, PFKL and PFKP, presenting different regulatory and catalytic properties. The expression of these isoforms is tissue-specific and vary according to the cell differentiation and signalization. Although it is known that the expression of the different PFK isoforms directly affects cell function, the information regarding the regulation of PFK isoforms expression is scarce. In the present work, we evaluate the role of insulin signalization on the expression of three PFK isoforms on skeletal muscle, liver, and epididymal white adipose tissue (eWAT) of mice. For this, Swiss mice were treated with streptozotocin (STZ) to disrupt pancreatic ß-cells and, thus, insulin production. Control group were treated with citrate buffer (STZ vehicle). These groups were then treated with insulin or saline twice a day for ten consecutive days when animals were euthanized and tissues used for the evaluation of PFK isoforms expression by quantitative PCR (qPCR). Our results revealed that the lack of insulin significantly impacted the expression of PFKL, presenting mild effects on PFKM and no effects on PFKP. The decrease of PFKL and PFKM mRNA levels observed on the group treated with STZ was reversed by the treatment with insulin. In conclusion, insulin, the most known regulator of glucose consumption, specifically regulates the expression of PFKL and PFKM, which impact the regulation of glycolysis in the cell.
Assuntos
Insulina/farmacologia , Fígado/enzimologia , Músculo Esquelético/enzimologia , Fosfofrutoquinase-1/metabolismo , Tecido Adiposo Branco/efeitos dos fármacos , Tecido Adiposo Branco/enzimologia , Animais , Isoenzimas/metabolismo , Fígado/efeitos dos fármacos , Masculino , Camundongos , Músculo Esquelético/efeitos dos fármacosRESUMO
Cholinergic anti-inflammatory pathway (CAP) prevents inflammatory cytokines production. The main was to evaluate the effect of maternal obesity on cholinergic pathway in the offspring. Female mice were subjected to either standard chow (SC) or high-fat diet (HFD) during pregnancy and the lactation period. After weaning, only male offspring from HFD dams (HFD-O) and from SC dams (SC-O) were fed the SC diet. Key proteins of the CAP were downregulated and serum TNF-α was elevated in the HFD-O mice. STAT3 and NF-κB activation in HFD-O mice ICV injected with nicotine (agonist) were lower than SC-O mice. Basal cholinesterase activity was upregulated in HFD-O mice in both investigated tissues. Lipopolysaccharide increased TNF-α and IL-1ß expression in the liver and WAT of SC-O mice, but this effect was greater in HFD-O mice. In conclusion these changes exacerbated cytokine production in response to LPS and contributed to the reduced sensitivity of the CAP.
Assuntos
Tecido Adiposo Branco/enzimologia , Dieta Hiperlipídica/efeitos adversos , Lactação/efeitos dos fármacos , Fígado/enzimologia , Obesidade/imunologia , Gravidez/efeitos dos fármacos , Receptor Nicotínico de Acetilcolina alfa7/metabolismo , Tecido Adiposo Branco/efeitos dos fármacos , Animais , Colinesterases/metabolismo , Citocinas/metabolismo , Feminino , Regulação da Expressão Gênica/efeitos dos fármacos , Lactação/imunologia , Lipopolissacarídeos/farmacologia , Fígado/efeitos dos fármacos , Masculino , Fenômenos Fisiológicos da Nutrição Materna , Camundongos , Obesidade/enzimologia , Obesidade/etiologiaRESUMO
Lipolysis is defined as the sequential hydrolysis of triacylglycerol (TAG) stored in cell lipid droplets. For many years, it was believed that hormone-sensitive lipase (HSL) and monoacylglycerol lipase (MGL) were the main enzymes catalyzing lipolysis in the white adipose tissue. Since the discovery of adipose triglyceride lipase (ATGL) in 2004, many studies were performed to investigate and characterize the actions of this lipase, as well as of other proteins and possible regulatory mechanisms involved, which reformulated the concept of lipolysis. Novel findings from these studies include the identification of lipolytic products as signaling molecules regulating important metabolic processes in many non-adipose tissues, unveiling a previously underestimated aspect of lipolysis. Thus, we present here an updated review of concepts and regulation of white adipocyte lipolysis with a special emphasis in its role in metabolism homeostasis and as a source of important signaling molecules.
Assuntos
Tecido Adiposo Branco/enzimologia , Lipase/metabolismo , Lipólise/fisiologia , Tecido Adiposo Branco/fisiologia , Humanos , Lipase/fisiologiaRESUMO
Lipolysis is defined as the sequential hydrolysis of triacylglycerol (TAG) stored in cell lipid droplets. For many years, it was believed that hormone-sensitive lipase (HSL) and monoacylglycerol lipase (MGL) were the main enzymes catalyzing lipolysis in the white adipose tissue. Since the discovery of adipose triglyceride lipase (ATGL) in 2004, many studies were performed to investigate and characterize the actions of this lipase, as well as of other proteins and possible regulatory mechanisms involved, which reformulated the concept of lipolysis. Novel findings from these studies include the identification of lipolytic products as signaling molecules regulating important metabolic processes in many non-adipose tissues, unveiling a previously underestimated aspect of lipolysis. Thus, we present here an updated review of concepts and regulation of white adipocyte lipolysis with a special emphasis in its role in metabolism homeostasis and as a source of important signaling molecules.
Assuntos
Humanos , Tecido Adiposo Branco/enzimologia , Lipase/metabolismo , Lipólise/fisiologia , Tecido Adiposo Branco/fisiologia , Lipase/fisiologiaRESUMO
The 72âkDa inositol polyphosphate 5-phosphatase E (72k-5ptase) controls signal transduction through the catalytic dephosphorylation of the 5-position of membrane-bound phosphoinositides. The reduction of 72k-5ptase expression in the hypothalamus results in improved hypothalamic insulin signal transduction and reduction of food intake and body mass. Here, we evaluated the tissue distribution and the impact of obesity on the expression of 72k-5ptase in peripheral tissues of experimental animals. In addition, insulin signal transduction and action were determined in an animal model of obesity and insulin resistance treated with an antisense (AS) oligonucleotide that reduces 72k-5ptase expression. In lean Wistar rats, 72k-5ptase mRNA and protein are found in highest levels in heart, skeletal muscle, and white adipose tissue. In three distinct models of obesity, Wistar rats, Swiss mice fed on high-fat diet, and leptin-deficient ob/ob mice, the expression of 72k-5ptase is increased in skeletal muscle and adipose tissue. The treatment of obese Wistar rats with an anti-72k-5ptase AS oligonucleotide results in significant reduction of 72k-5ptase catalytic activity, which is accompanied by reduced food intake and body mass and improved insulin signal transduction and action as determined by immunoblotting and clamp studies respectively. 72k-5ptase expression is increased in obesity and its AS inhibition resulted in a significant improvement in insulin signal transduction and restoration of glucose homeostasis.
Assuntos
Dieta Hiperlipídica/efeitos adversos , Insulina/fisiologia , Obesidade/etiologia , Obesidade/fisiopatologia , Monoéster Fosfórico Hidrolases/antagonistas & inibidores , Transdução de Sinais/fisiologia , Tecido Adiposo Branco/enzimologia , Animais , Modelos Animais de Doenças , Inositol Polifosfato 5-Fosfatases , Resistência à Insulina/fisiologia , Leptina/deficiência , Masculino , Camundongos , Camundongos Obesos , Músculo Esquelético/enzimologia , Miocárdio/enzimologia , Obesidade/metabolismo , Oligorribonucleotídeos Antissenso/farmacologia , Monoéster Fosfórico Hidrolases/efeitos dos fármacos , Monoéster Fosfórico Hidrolases/metabolismo , Ratos , Ratos WistarRESUMO
Leptin is a 16â kDa hormone mainly produced by adipocytes that plays an important role in many biological events including the regulation of appetite and energy balance, atherosclerosis, osteogenesis, angiogenesis, the immune response, and inflammation. The search for proteolytic enzymes capable of processing leptin prompted us to investigate the action of cysteine cathepsins on human leptin degradation. In this study, we observed high cysteine peptidase expression and hydrolytic activity in white adipose tissue (WAT), which was capable of degrading leptin. Considering these results, we investigated whether recombinant human cysteine cathepsins B, K, L, and S were able to degrade human leptin. Mass spectrometry analysis revealed that among the tested enzymes, cathepsin S exhibited the highest catalytic activity on leptin. Furthermore, using a Matrigel assay, we observed that the leptin fragments generated by cathepsin S digestion did not exhibit angiogenic action on endothelial cells and were unable to inhibit food intake in Wistar rats after intracerebroventricular administration. Taken together, these results suggest that cysteine cathepsins may be putative leptin activity regulators in WAT.