AMPK-能量代谢感受器与可激活AMPK相关的药物研究进展

单磷酸腺苷活化蛋白激酶(AMPK)可以感受细胞能量代谢变化,调节细胞的葡萄糖、脂肪酸的代谢过程。AMPK与细胞生长、生存和多种代谢信号途径关系密切,研究发现AMPK信号途径涉及炎症、肿瘤和代谢疾病。本文综述AMPK的功能与炎症、肿瘤、代谢类疾病的关系和诸如水杨酸、二甲双胍等药物激活AMPK的研究进展。     

AMPK-能量代谢感受器与可激活AMPK相关的药物研究进展

单磷酸腺苷活化蛋白激酶（AMPK）可以感受细胞能量代谢变化,调节细胞的葡萄糖、脂肪酸的代谢过程。AMPK与细胞生长、生存和多种代谢信号途径关系密切,研究发现AMPK信号途径涉及炎症、肿瘤和代谢疾病。本文综述AMPK的功能与炎症、肿瘤、代谢类疾病的关系和诸如水杨酸、二甲双胍等药物激活AMPK的研究进展。     

AMPK与胰岛素抵抗

腺苷酸活化蛋白激酶(AMPK)是一种重要的蛋白激酶,主要作用是协调代谢和能量平衡。AMPK被激活后在增加骨骼肌对葡萄糖摄取、增强胰岛素敏感性、增加脂肪酸氧化以及调节基因转录等方面发挥重要作用。由于在调节糖和脂肪酸代谢方面的作用,AMPK可能为治疗肥胖、胰岛素抵抗和2型糖尿病提供了新的药理靶点。     

AMPK在运动介导的骨骼肌糖脂代谢中的作用

运动可以调节代谢酶的活性及表达,刺激骨骼肌代谢,增加脂肪酸氧化、葡萄糖转运和糖原合成,从而改善骨骼肌的胰岛素抵抗。AMP激活的蛋白激酶(AMPK)是参与这一过程的重要途径之一。AMPK是一个能量感受器,在运动时,它可以感受骨骼肌中增高的AMP/ATP而被激活,调节骨骼肌的代谢,促进脂肪酸氧化和葡萄糖转运,减少骨骼肌中甘油三酯的堆积,改善胰岛素抵抗。     

AMPK在运动介导的骨骼肌糖脂代谢中的作用

运动可以调节代谢酶的活性及表达，刺激骨骼肌代谢，增加脂肪酸氧化、葡萄糖转运和糖原合成，从而改善骨骼肌的胰岛素抵抗。AMP激活的蛋白激酶(AMPK)是参与这一过程的重要途径之一。AMPK是一个能量感受器，在运动时，它可以感受骨骼肌中增高的AMP／ATP而被激活，调节骨骼肌的代谢，促进脂肪酸氧化和葡萄糖转运，减少骨骼肌中甘油三酯的堆积，改善胰岛素抵抗。     

腺苷酸活化蛋白激酶与心血管疾病

1973年,Gobson和Carlson分别报道了腺苷酸活化蛋白激酶(adenosine monophosphate-activated protein kinase,AMPK)广泛存在真核细胞生物中,通过影响细胞物质代谢的多个环节来维持细胞能量供求平衡和调节细胞功能.细胞能量不足时会激活AMPK,一方面抑制糖原、脂肪和胆固醇的合成,减少ATP的利用;另一方面,促进脂肪酸氧化、葡萄糖转运等,增加ATP的产生.反之,当细胞内存在高浓度的ATP则可以抑制该效应.……     

单磷酸腺苷活化蛋白激酶与肾脏疾病

单磷酸腺苷活化蛋白激酶(AMPK)是体内一种重要的蛋白激酶,广泛分布于全身各组织器官,发挥不同的功能.AMPK作为“细胞能量调节器”来调节糖、脂代谢及蛋白质合成,并参与调控机体炎症反应和细胞增生等过程,参与多种疾病(如动脉粥样硬化、肿瘤、糖尿病和其他代谢性疾病)的发生发展.近年来随着研究的深入,AMPK与肾脏疾病的关系逐渐受到关注.     

腺苷酸活化蛋白激酶与心肌缺血再灌注损伤

心肌缺血再灌注损伤（MIRI）是指缺血期处于可逆损伤的心肌细胞恢复血液供应后产生更为严重的损伤,主要包括炎症反应、内皮细胞损伤、血流障碍、心肌细胞坏死和凋亡所致心肌梗死面积的扩大、再灌注心律失常、心肌顿抑及冠状微循环障碍等病理生理变化.腺苷酸活化蛋白激酶（5-adenosine monophosphate activated kinase,AMPK）通过调节多种代谢途径控制着心脏能量的供求平衡.AMPK不仅控制葡萄糖和脂类的摄入、储存和利用,还能调节多种代谢酶的活性以及离子通道的开放和相关基因的表达[1].AMPK还能够调节缺血再灌注过程中心肌能量代谢,降低缺血性损伤和心肌凋亡.因此,AMPK被认为是能量应激下心肌细胞代谢调节的关键激酶.     

腺苷酸活化蛋白激酶对糖脂代谢的影响

腺苷酸活化蛋白激酶 (AMPK)是一种重要的代谢应激蛋白激酶 ,在运动、缺氧等应激条件下可被高浓度的腺苷酸别构激活 ,AMPK一旦活化就可以使许多参与葡萄糖摄取和脂肪酸氧化的蛋白磷酸化 ,促进葡萄糖摄取 ,增加脂肪酸氧化 ,增加能量消耗 ,并且可以调控葡萄糖诱导基因的转录。 5 氨基 4 甲酰胺咪唑核糖核苷酸 (AICAR)是AMPK的非特异性激动剂 ,运动的急性效应 (增加骨骼肌葡萄糖摄取 )和慢性效应 (增加葡萄糖转运子 4 )都可以被AICAR所重复。AMPK可能在 2型糖尿病的运动治疗中发挥了重要作用。     

AMPK在2型糖尿病及其心血管并发症的作用

磷酸腺苷蛋白激酶(AMP-activated protein kinase,AMPK)是一种调节细胞内能量代谢的酶.它的主要特征是能与AMP结合,并通过AMP感知细胞的能量水平和代谢平衡水平来调节酶的活性.     

Exercise-induced AMPK activity in skeletal muscle: Role in glucose uptake and insulin sensitivity

The energy/fuel sensor 5′-AMP-activated protein kinase (AMPK) is viewed as a master regulator of cellular energy balance due to its many roles in glucose, lipid, and protein metabolism. In this review we focus on the regulation of AMPK activity in skeletal muscle and its involvement in glucose metabolism, including glucose transport and glycogen synthesis. In addition, we discuss the plausible interplay between AMPK and insulin signaling regulating these processes.     

AMP-activated protein kinase activates p38 mitogen-activated protein kinase by increasing recruitment of p38 MAPK to TAB1 in the ischemic heart

AMP-activated protein kinase (AMPK) promotes glucose transport, maintains ATP stores, and prevents injury and apoptosis during ischemia. AMPK has several direct molecular targets in the heart but also may interact with other stress-signaling pathways. This study examined the role of AMPK in the activation of the p38 mitogen-activated protein kinase (MAPK). In isolated heart muscles, the AMPK activator 5-aminoimidazole-4-carboxy-amide-1-beta-D-ribofuranoside (AICAR) increased p38 MAPK activation. In AMPK-deficient mouse hearts, expressing a kinase-dead (KD) alpha2 catalytic subunit, p38 MAPK activation was markedly reduced during low-flow ischemia (2.3- versus 7-fold in wild-type hearts, P<0.01) and was similarly reduced during severe no-flow ischemia in KD hearts (P<0.01 versus ischemic wild type). Knockout of the p38 MAPK upstream kinase, MAPK kinase 3 (MKK3), did not affect ischemic activation of either AMPK or p38 MAPK in transgenic mkk3(-/-) mouse hearts. Ischemia increased p38 MAPK recruitment to transforming growth factor-beta-activated protein kinase 1-binding protein 1 (TAB1), a scaffold protein that promotes p38 MAPK autophosphorylation. Moreover, TAB1 was associated with the alpha2 catalytic subunit of AMPK. p38 MAPK recruitment to TAB1/AMPK complexes required AMPK activation and was reduced in ischemic AMPK-deficient transgenic mouse hearts. The potential role of p38 MAPK in mediating the downstream action of AMPK to promote glucose transport was also assessed. The p38 MAPK inhibitor SB203580 partially inhibited both AICAR- and hypoxia-stimulated glucose uptake and GLUT4 translocation. Activation of p38 MAPK by anisomycin also increased glucose transport in heart muscles. Thus, AMPK has an important role in promoting p38 MAPK activation in the ischemic heart by inducing p38 MAPK autophosphorylation through interaction with the scaffold protein TAB1.     

Suppression of AMPK activation via S485 phosphorylation by IGF-I during hyperglycemia is mediated by AKT activation in vascular smooth muscle cells

As a metabolic sensor, the serine/threonine protein kinase AMP-activated protein kinase (AMPK) promotes the adaptation of cells to signals arising from nutrients, hormones, and growth factors. The ability of IGF-I to stimulate protein synthesis is suppressed by AMPK, therefore, these studies were undertaken to determine whether IGF-I modulates AMPK activity. IGF-I dose-dependently suppressed phosphorylation of AMPK T172, and it stimulated AMPK S485 phosphorylation in vascular smooth muscle cells (VSMC). To determine whether stimulation of AMPK S485 phosphorylation was mediating this response, VSMC were transduced with a mutant AMPKα (AMPK S485A). Expression of this altered form inhibited the ability of IGF-I to suppress AMPK T172 activation, which resulted in inhibition of IGF-I-stimulated phosphorylation of P70S6 kinase. In contrast, expression of an AMPK S485D mutant resulted in constitutive suppression of AMPK activity and was associated with increased IGF-I-stimulated P70S6K phosphorylation and protein synthesis. The addition of a specific AKT inhibitor or expression of an AKT1 short hairpin RNA inhibited AMPK S485 phosphorylation, and it attenuated the IGF-I-induced decrease in AMPK T172 phosphorylation. Exposure to high glucose concentrations suppressed AMPK activity and stimulated S485 phosphorylation, and IGF-I stimulated a further increase in S485 phosphorylation and AMPK T172 suppression. We conclude that AMPK S485 phosphorylation negatively regulates AMPK activity by modulating the T172 phosphorylation response to high glucose and IGF-I. IGF-I stimulates S485 phosphorylation through AKT1. The results suggest that AMPK plays an inhibitory role in modulating IGF-I-stimulated protein synthesis and that IGF-I must down-regulate AMPK activity to induce an optimal anabolic response.     

Insulin signalling downstream of protein kinase B is potentiated by 5′AMP-activated protein kinase in rat hearts in vivo

Aims/hypothesis 5′AMP-activated protein kinase (AMPK) and insulin stimulate glucose transport in heart and muscle. AMPK acts in an additive manner with insulin to increase glucose uptake, thereby suggesting that AMPK activation may be a useful strategy for ameliorating glucose uptake, especially in cases of insulin resistance. In order to characterise interactions between the insulin- and AMPK-signalling pathways, we investigated the effects of AMPK activation on insulin signalling in the rat heart in vivo. Methods Male rats (350–400 g) were injected with 1 g/kg 5-aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR) or 250 mg/kg metformin in order to activate AMPK. Rats were administered insulin 30 min later and after another 30 min their hearts were removed. The activities and phosphorylation levels of components of the insulin-signalling pathway were subsequently analysed in individual rat hearts. Results AICAR and metformin administration activated AMPK and enhanced insulin signalling downstream of protein kinase B in rat hearts in vivo. Insulin-induced phosphorylation of glycogen synthase kinase 3 (GSK3) β, p70 S6 kinase (p70^S6K)(Thr389) and IRS1(Ser636/639) were significantly increased following AMPK activation. To the best of our knowledge, this is the first report of heightened insulin responses of GSK3β and p70^S6K following AMPK activation. In addition, we found that AMPK inhibits insulin stimulation of IRS1-associated phosphatidylinositol 3-kinase activity, and that AMPK activates atypical protein kinase C and extracellular signal-regulated kinase in the heart. Conclusions/interpretations Our data are indicative of differential effects of AMPK on the activation of components in the cardiac insulin-signalling pathway. These intriguing observations are critical for characterisation of the crosstalk between AMPK and insulin signalling.     

Insulin resistance and improvements in signal transduction

Type 2 diabetes and obesity are common metabolic disorders characterized by resistance to the actions of insulin to stimulate skeletal muscle glucose disposal. Insulin-resistant muscle has defects at several steps of the insulin-signaling pathway, including decreases in insulin-stimulated insulin receptor and insulin receptor substrate-1 tyrosine phosphorylation, and phosphatidylinositol 3-kinase (Pl 3-kinase) activation. One approach to increase muscle glucose disposal is to reverse/improve these insulin-signaling defects. Weight loss and thiazolidinediones (TZDs) improve glucose disposal, in part, by increasing insulin-stimulated insulin receptor and IRS-1 tyrosine phosphorylation and PI 3-kinase activity. In contrast, physical training and metformin improve whole-body glucose disposal but have minimal effects on proximal insulin-signaling steps. A novel approach to reverse insulin resistance involves inhibition of the stress-activated protein kinase Jun N-terminal kinase (JNK) and the protein tyrosine phosphatases (PTPs). A different strategy to increase muscle glucose disposal is by stimulating insulin-independent glucose transport. AMP-activated protein kinase (AMPK) is an enzyme that works as a fuel gauge and becomes activated in situations of energy consumption, such as muscle contraction. Several studies have shown that pharmacologic activation of AMPK increases glucose transport in muscle, independent of the actions of insulin. AMPK activation is also involved in the mechanism of action of metformin and adiponectin. Moreover, in the hypothalamus, AMPK regulates appetite and body weight. The effect of AMPK to stimulate muscle glucose disposal and to control appetite makes it an important pharmacologic target for the treatment of type 2 diabetes and obesity.     

The AMP-regulated kinase family: enigmatic targets for diabetes therapy

AMP-activated protein kinase (AMPK) is a widely conserved Ser/Thr-specific protein kinase, homologous to Saccharomyces cerevisiae Snf1, and involved in nutrient sensing in lower organisms. In 2003, we reviewed the role of this enzyme in glucose homeostasis in mammals [Rutter, G.A., daSilvaXavier, G., Leclerc, I., 2003. Roles of 5'-AMP-activated protein kinase (AMPK) in mammalian glucose homoeostasis. Biochem. J. 375 (Pt 1), 1-16]. In the subsequent 5 years, dramatic strides have taken place in our understanding of the role of AMPK in the control of whole body metabolic homeostasis, the regulation of the enzyme by upstream kinases, and its molecular structure. These new studies and earlier work arguably propel AMPK, and perhaps related family members into a "super league" of potential therapeutic targets for maladies including diabetes, cancer, heart disease, and obesity. Here, we survey some of these recent advances, focussing on the role of this and related enzymes in the control of pancreatic beta-cell function and glucose homeostasis.     

Targeting AMP-activated protein kinase as a novel therapeutic approach for the treatment of metabolic disorders

In the light of recent studies in humans and rodents, AMP-activated protein kinase (AMPK), a phylogenetically conserved serine/threonine protein kinase, has been described as an integrator of regulatory signals monitoring systemic and cellular energy status. AMP-activated protein kinase (AMPK) has been proposed to function as a 'fuel gauge' to monitor cellular energy status in response to nutritional environmental variations. Recently, it has been proposed that AMPK could provide a link in metabolic defects underlying progression to the metabolic syndrome. AMPK is a heterotrimeric enzyme complex consisting of a catalytic subunit and two regulatory subunits β and γ. AMPK is activated by rising AMP and falling ATP. AMP activates the system by binding to the γ subunit that triggers phosphorylation of the catalytic subunit by the upstream kinases LKB1 and CaMKKβ (calmodulin-dependent protein kinase kinase). AMPK system is a regulator of energy balance that, once activated by low energy status, switches on ATP-producing catabolic pathways (such as fatty acid oxidation and glycolysis), and switches off ATP-consuming anabolic pathways (such as lipogenesis), both by short-term effect on phosphorylation of regulatory proteins and by long-term effect on gene expression. As well as acting at the level of the individual cell, the system also regulates food intake and energy expenditure at the whole body level, in particular by mediating the effects of insulin sensitizing adipokines leptin and adiponectin. AMPK is robustly activated during skeletal muscle contraction and myocardial ischaemia playing a role in glucose transport and fatty acid oxidation. In liver, activation of AMPK results in enhanced fatty acid oxidation as well as decreased glucose production. Moreover, the AMPK system is one of the probable targets for the anti-diabetic drugs biguanides and thiazolidinediones. Thus, the relationship between AMPK activation and beneficial metabolic effects provide the rationale for the development of new therapeutic strategies in metabolic disorders.     

AMP-activated protein kinase: Role in metabolism and therapeutic implications

AMP-activated protein kinase (AMPK) is an enzyme that works as a fuel gauge which becomes activated in situations of energy consumption. AMPK functions to restore cellular ATP levels by modifying diverse metabolic and cellular pathways. In the skeletal muscle, AMPK is activated during exercise and is involved in contraction-stimulated glucose transport and fatty acid oxidation. In the heart, AMPK activity increases during ischaemia and functions to sustain ATP, cardiac function and myocardial viability. In the liver, AMPK inhibits the production of glucose, cholesterol and triglycerides and stimulates fatty acid oxidation. Recent studies have shown that AMPK is involved in the mechanism of action of metformin and thiazolidinediones, and the adipocytokines leptin and adiponectin. These data, along with evidence that pharmacological activation of AMPK in vivo improves blood glucose homeostasis, cholesterol concentrations and blood pressure in insulin-resistant rodents, make this enzyme an attractive pharmacological target for the treatment of type 2 diabetes, ischaemic heart disease and other metabolic diseases.