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。     

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在急性胰腺炎中的作用

腺苷酸活化蛋白激酶(AMPK)作为细胞内的一种重要能量及代谢调节酶,能够有效维持细胞及机体能量及代谢稳态,在人体健康和疾病中发挥重要作用。目前研究表明,AMPK能通过作用NF-κB、TNFα、IL-6等炎症细胞因子及信号通路调节机体炎症反应,成为多种炎症疾病重要潜在治疗靶点。急性胰腺炎是由于胰酶异常激活消化自身组织细胞,释放NF-κB、TNFα、IL-6等多种炎症因子,诱发全身炎症反应,导致全身组织器官损伤急性炎症疾病。目前研究表明激活AMPK能够一定程度上减轻急性胰腺炎炎症损伤。因此,AMPK及其信号通路有望成为急性胰腺炎的潜在治疗靶点。     

AMPK信号通路和NLRP3炎症小体在肝衰竭中的研究进展

肝衰竭是由多种因素导致的严重肝脏结构和功能损伤，且是一个涉及“三重打击”的复杂病理生理过程。在机体内，AMPK信号在调节细胞能量平衡中起着重要作用。肝脏作为机体的代谢工厂，对能量的产生和利用有着严格的调控。此外，NLRP3炎症小体也在众多炎症性疾病发生发展过程中扮演着重要角色。而AMPK信号通路和NLRP3小体之间存在交互影响。本文就AMPK介导的多种信号通路、NLRP3炎症小体的激活效应及二者之间的相互作用在肝衰竭过程中的研究进展做一综述。     

腺苷单磷酸激活蛋白激酶参与调控心脏能量代谢的研究进展

腺苷单磷酸激活蛋白激酶(AMPK)是细胞中重要的代谢传感器,主要参与维持代谢应激下能量平衡和氧化还原稳态,与心脏能量代谢密切相关。活化的AMPK可以增强分解代谢、抑制合成代谢、上调ATP水平,也参与调节糖代谢、胆固醇代谢、脂肪酸及蛋白质代谢等过程,为细胞的生长过程提供能量储备;同时活化的AMPK还与新生血管形成、转移、炎症等病理过程息息相关。     

AMPK与肥胖

能量代谢平衡失调是肥胖发生的主要原因。腺苷酸激活蛋白激酶(AMPK)信号通路是调节细胞能量状态的中心环节,其激活后磷酸化下游的信号分子,关闭消耗ATP的合成代谢途径,开启产生ATP的分解代谢途径,被称为"细胞能量调节器",在增加骨骼肌对葡萄糖的摄取、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。在整体水平,AMPK通过激素和细胞因子如瘦素、脂联素和ghrelin等调节能量的摄入和消耗。研究AMPK与肥胖的关系,将为AMPK作为防治肥胖的新靶点提供可靠的理论基础和应用依据。     

肥胖、代谢综合征与炎症

流行病学、临床及实验研究结果提示,肥胖和炎症的关系是代谢综合征共同土壤的重要组成部分。肥胖和有关的代谢病生理变化伴有慢性炎症反应,产生异常的细胞因子及激活炎症信号通路,与肥胖本身以及与其密切相关的疾病状态之间存在因果关系。肥胖时炎症反应的重要特征在于它是被启动的、最初主要位于脂肪组织,其中白色脂肪组织中的巨噬细胞和炎症相关因子基因起着重要作用。炎症指标可能用于代谢综合征的预测和诊断。对肥胖与炎症之间关系的新认识为防治代谢综合征提供了新的途径。     

腺苷酸激活蛋白激酶在脂肪组织中的作用

腺苷酸激活蛋白激酶（AMPK）是细胞和机体能量代谢的主要调节器。组织缺氧、低血糖、禁食和运动可以激活脂肪细胞中的AMPK。AMPK活化后能通过磷酸化下游信号分子,刺激能量生成途径（葡萄糖转运,脂肪酸氧化）关闭能量消耗的途径（脂肪、蛋白质、糖类的生成）。现在已经明确脂肪组织不仅是能量储存的场所,也在能量平衡以及其它很多过程中发挥作用。研究AMPK与脂肪组织的关系,将为AMPK作为防治肥胖的新靶点提供可靠的理论基础和应用依据。     

肥胖、代谢综合征与炎症

流行病学、临床及实验研究结果提示，肥胖和炎症的关系是代谢综合征共同土壤的重要组成部分。肥胖和有关的代谢病生理变化伴有慢性炎症反应，产生异常的细胞因子及激活炎症信号通路，与肥胖本身以及与其密切相关的疾病状态之间存在因果关系。肥胖时炎症反应的重要特征在于它是被启动的、最初主要位于脂肪组织，其中白色脂肪组织中的巨噬细胞和炎症相关因子基因起着重要作用。炎症指标可能用于代谢综合征的预测和诊断。对肥胖与炎症之间关系的新认识为防治代谢综合征提供了新的途径。     

Raf-蛋白激酶研究新进展

细胞外刺激引起的细胞异常增殖和细胞外基质的过度积聚是多种增殖、硬化性疾病（如炎症、肿瘤等）的病理基础。目前已发现了多条与细胞增殖或分化相关的细胞内信号传导途径,为有关疾病的研究开辟了新的领域。细胞作为一个整体对外界刺激的反应是其自身整体协调的结果,对各类信号传导途径之间的交互作用进行研究并寻找其交联点,将有助于从整体上对细胞的生物学行为加以调控并找出相关疾病防治的突破口。在目前已知的与细胞增殖分化调控密切相关的信号传导途径中,Ｒａｆ１蛋白激酶是酪氨酸激酶相关的信号传导途径中的重要信号分子之一。…     

Tangeretin stimulates glucose uptake via regulation of AMPK signaling pathways in C2C12 myotubes and improves glucose tolerance in high-fat diet-induced obese mice

Although the flavonoid tangeretin (5, 6, 7, 8, 4'-pentamethoxyflavone) is known to possess beneficial health effects, the anti-diabetic effects and the mechanism of action have not been elucidated. Treatment with 100 μM tangeretin significantly increased the uptake of 2-NBDG in C2C12 myotubes. We also found that AMPK and AS160 were markedly phosphorylated by tangeretin treatment. In addition, pretreatment with an AMPK inhibitor significantly abrogated tangeretin-stimulated AS160 phosphorylation, glucose uptake, and Glut4 translocation from the cytosol to the plasma membrane. Furthermore, disruption of AMPK using siRNA transfection prevented the glucose uptake stimulated by tangeretin. We also examined the anti-diabetic properties of tangeretin in mice on HFD. Administration of HFD plus 200 mg/kg of tangeretin significantly altered weight gain, glucose tolerance, total cholesterol levels, and the secretion of adipocytokines, such as adiponectin, leptin, resistin, IL-6, and MCP-1. Moreover, AMPK was activated by 200 mg/kg of tangeretin in mouse muscle tissue, as expected from the cell system. These results suggest that tangeretin exerts anti-diabetic effects in both cell culture and mouse models, and these effects are necessary for activating AMPK.     

Enhanced muscle fat oxidation and glucose transport by ACRP30 globular domain: acetyl-CoA carboxylase inhibition and AMP-activated protein kinase activation

gACRP30, the globular subunit of adipocyte complement-related protein of 30 kDa (ACRP30), improves insulin sensitivity and increases fatty acid oxidation. The mechanism by which gACRP30 exerts these effects is unknown. Here, we examined if gACRP30 activates AMP-activated protein kinase (AMPK), an enzyme that has been shown to increase muscle fatty acid oxidation and insulin sensitivity. Incubation of rat extensor digitorum longus (EDL), a predominantly fast twitch muscle, with gACRP30 (2.5 micro g/ml) for 30 min led to 2-fold increases in AMPK activity and phosphorylation of both AMPK on Thr-172 and acetyl CoA carboxylase (ACC) on Ser-79. Accordingly, concentration of malonyl CoA was diminished by 30%. In addition, gACRP30 caused a 1.5-fold increase in 2-deoxyglucose uptake. Similar changes in malonyl CoA and ACC were observed in soleus muscle incubated with gACRP30 (2.5 micro g/ml), although no significant changes in AMPK activity or 2-deoxyglucose uptake were detected. When EDL was incubated with full-length hexameric ACRP30 (10 micro g/ml), AMPK activity and ACC phosphorylation were not altered. Administration of gACRP30 (75 micro g) to C57 BL6J mice in vivo led to increased AMPK activity and ACC phosphorylation and decreased malonyl CoA concentration in gastrocnemius muscle within 15-30 min. Both in vivo and in vitro, activation of AMPK was the first effect of gACRP30 and was transient, whereas alterations in malonyl CoA and ACC occurred later and were more sustained. Thus, gACRP30 most likely exerts its actions on muscle fatty acid oxidation by inactivating ACC via activation of AMPK and perhaps other signal transduction proteins.     

Apelin stimulates glucose uptake but not lipolysis in human adipose tissue ex vivo

Apelin is a peptide present in different cell types and secreted by adipocytes in humans and rodents. Apelin exerts its effects through a G-protein-coupled receptor called APJ. During the past years, a role of apelin/APJ in energy metabolism has emerged. Apelin was shown to stimulate glucose uptake in skeletal muscle through an AMP-activated protein kinase (AMPK)-dependent pathway in mice. So far, no metabolic effects of apelin have been reported on human adipose tissue (AT). Thus, the effect of apelin on AMPK in AT was measured as well as AMPK-mediated effects such as inhibition of lipolysis and stimulation of glucose uptake. AMPK and acetyl-CoA carboxylase phosphorylation were measured by western blot to reflect the AMPK activity. Lipolysis and glucose uptake were measured, ex vivo, in response to apelin on isolated adipocytes and explants from AT of the subcutaneous region of healthy subjects (body mass index: 25.6 ± 0.8 kg/m(2), n = 30 in total). APJ mRNA and protein are present in human AT and isolated adipocytes. Apelin stimulated AMPK phosphorylation at Thr-172 in a dose-dependent manner in human AT, which was associated with increased glucose uptake since C compound (20 μM), an AMPK inhibitor, completely prevented apelin-induced glucose uptake. However, in isolated adipocytes or AT explants, apelin had no significant effect on basal and isoprenaline-stimulated lipolysis. Thus, these results reveal, for the first time, that apelin is able to act on human AT in order to stimulate AMPK and glucose uptake.     

小檗碱的降糖作用独立于AMPK的信号通路

目的：研究小檗碱的降糖作用是否依赖于单磷酸腺苷激活蛋白激酶（AMPK）信号途径。方法培养HepG2细胞和C2C12细胞,给予不同浓度小檗碱处理。葡萄糖消耗实验和乳酸生成实验用于检测小檗碱的降糖以及刺激糖酵解的作用。AMPK抑制剂化合物C（Compound C,CC）和显性失活突变型AMPK,即腺病毒负显性AMPK（Ad-DN-AMPK）腺病毒用于抑制AMPK的表达和活性。Western印迹法用于检测AMPK以及乙酰辅酶A羧化酶（ACC）磷酸化水平,以评估AMPK通路的活性。结果小檗碱显著刺激了HepG2细胞和C2C12细胞的葡萄糖消耗和乳酸生成,并表现出剂量依赖性的药物作用。5和10μmol/L的小檗碱显著增加AMPK及其下游蛋白ACC的磷酸化水平。CC和Ad-DN-AMPK腺病毒转染能明显抑制细胞内AMPK信号通路的活性。然而,在AMPK活性被抑制的条件下,小檗碱依然能够显著增加细胞的葡萄糖消耗和乳酸生成。结论小檗碱通过刺激糖酵解而上调细胞的糖代谢,该作用无需AMPK信号通路的参与。即使在AMPK的表达或者活性被抑制的情况下,小檗碱依然能够发挥显著的降糖作用。     

抵抗素对内皮细胞一氧化氮生成的影响及其AMPK信号机制

目的研究抵抗素对人脐静脉内皮细胞（HUVEC）一氧化氮生成的影响及其信号机制。方法不同浓度人抵抗素（0-100ng／ml）干预HUVEC24h。DAF-2DA染色,激光共聚焦显微镜观察各组一氧化氮生成改变,Western-Blot检测各组eNOS、AMPK磷酸化水平改变。结果15、50、100ng／ml抵抗素干预HUVEC24h后,3组的一氧化氮生成分别为4．014-0．69、3．76±0．71、3．73±0．45,与对照组一氧化氮生成（4．89±0．58）相比显著降低（P〈0.05）;50ng／ml组添加AMPK特异激动剂A／CAR后,一氧化氮生成（5．08±0．70）显著升高（P〈0.01）。各抵抗素干预组的AMPK和eNOS磷酸化水平均明显降低;而添加AMPK特异激动剂AICAR后,伴随AMPK的激活,eNOS磷酸化水平也显著增高（P〈0．05）。结论抵抗素在内皮细胞可通过对AMPK的抑制进而导致eNOS失调,降低内皮一氧化氮的生成。     

Adiponectin deficiency exacerbates cardiac dysfunction following pressure overload through disruption of an AMPK-dependent angiogenic response

Although increasing evidence indicates that an adipokine adiponectin exerts protective actions on heart, its effects on coronary angiogenesis following pressure overload have not been examined previously. Because disruption of angiogenesis during heart growth leads to contractile dysfunction and heart failure, we hypothesized that adiponectin modulates cardiac remodeling in response to pressure overload through its ability to regulate adaptive angiogenesis. Adiponectin-knockout (APN-KO) and wild-type (WT) mice were subjected to pressure overload caused by transverse aortic constriction (TAC). APN-KO mice exhibited greater cardiac hypertrophy, pulmonary congestion, left ventricular (LV) interstitial fibrosis and LV systolic dysfunction after TAC surgery compared with WT mice. APN-KO mice also displayed reduced capillary density in the myocardium after TAC, which was accompanied by a significant decrease in expression of vascular endothelial growth factor (VEGF) and phosphorylation of AMP-activated protein kinase (AMPK). Inhibition of AMPK in WT mice resulted in aggravated LV systolic function, attenuated myocardial capillary density and decreased VEGF expression in response to TAC. The adverse effects of AMPK inhibition on cardiac function and angiogenic response following TAC were diminished in APN-KO mice relative to WT mice. Moreover, adenovirus-mediated VEGF delivery reversed the TAC-induced deficiencies in cardiac microvessel formation and ventricular function observed in the APN-KO mice. In cultured cardiac myocytes, adiponectin treatment stimulated VEGF production, which was inhibited by inactivation of AMPK signaling pathway. Collectively, these data show that adiponectin deficiency can accelerate the transition from cardiac hypertrophy to heart failure during pressure overload through disruption of AMPK-dependent angiogenic regulatory axis.     

Berberine acutely inhibits insulin secretion from beta-cells through 3',5'-cyclic adenosine 5'-monophosphate signaling pathway

Berberine, a hypoglycemic agent, has recently been shown to activate AMP-activated protein kinase (AMPK) contributing to its beneficial metabolic effects in peripheral tissues. However, whether berberine exerts a regulatory effect on beta-cells via AMPK or other signaling pathways and counteracts glucolipotoxicity remains uncertain. In the present study, the impact of berberine on beta-cell function was investigated in vivo and in vitro. In high-fat-fed rats, berberine treatment for 6 wk significantly decreased plasma glucose and insulin levels before and after an oral glucose challenge along with the reduction of body weight and improvement of blood lipid profile. In accordance with the in vivo results, berberine acutely decreased glucose-stimulated insulin secretion (GSIS) and palmitate-potentiated insulin secretion in MIN6 cells and rat islets. However, pretreated with berberine for 24 h augmented the response of MIN6 cells and rat islets to glucose and attenuated the glucolipotoxicity. Berberine acutely increased AMPK activity in MIN6 cells. However, compound C, an AMPK inhibitor, completely reversed troglitazone-suppressed GSIS, not berberine-suppressed GSIS. Otherwise, berberine decreased cAMP-raising agent-potentiated insulin secretion in MIN6 cells and rat islets. These results suggest that the activation of AMPK is required for troglitazone-suppressed GSIS, whereas cAMP signaling pathway contributes, at least in part, to the regulatory effect of berberine on insulin secretion.     

AMP-activated protein kinase pathway and bone metabolism

There is increasing evidence that osteoporosis, similarly to obesity and diabetes, could be another disorder of energy metabolism. AMP-activated protein kinase (AMPK) has emerged over the last decade as a key sensing mechanism in the regulation of cellular energy homeostasis and is an essential mediator of the central and peripheral effects of many hormones on the metabolism of appetite, fat and glucose. Novel work demonstrates that the AMPK signaling pathway also plays a role in bone physiology. Activation of AMPK promotes bone formation in vitro and the deletion of α or β subunit of AMPK decreases bone mass in mice. Furthermore, AMPK activity in bone cells is regulated by the same hormones that regulate food intake and energy expenditure through AMPK activation in the brain and peripheral tissues. AMPK is also activated by antidiabetic drugs such as metformin and thiazolidinediones (TZDs), which also impact on skeletal metabolism. Interestingly, TZDs have detrimental skeletal side effects, causing bone loss and increasing the risk of fractures, although the role of AMPK mediation is still unclear. These data are presented in this review that also discusses the potential roles of AMPK in bone as well as the possibility for AMPK to be a future therapeutic target for intervention in osteoporosis.     

Phosphorylation of the voltage-gated potassium channel Kv2.1 by AMP-activated protein kinase regulates membrane excitability

Firing of action potentials in excitable cells accelerates ATP turnover. The voltage-gated potassium channel Kv2.1 regulates action potential frequency in central neurons, whereas the ubiquitous cellular energy sensor AMP-activated protein kinase (AMPK) is activated by ATP depletion and protects cells by switching off energy-consuming processes. We show that treatment of HEK293 cells expressing Kv2.1 with the AMPK activator A-769662 caused hyperpolarizing shifts in the current-voltage relationship for channel activation and inactivation. We identified two sites (S440 and S537) directly phosphorylated on Kv2.1 by AMPK and, using phosphospecific antibodies and quantitative mass spectrometry, show that phosphorylation of both sites increased in A-769662-treated cells. Effects of A-769662 were abolished in cells expressing Kv2.1 with S440A but not with S537A substitutions, suggesting that phosphorylation of S440 was responsible for these effects. Identical shifts in voltage gating were observed after introducing into cells, via the patch pipette, recombinant AMPK rendered active but phosphatase-resistant by thiophosphorylation. Ionomycin caused changes in Kv2.1 gating very similar to those caused by A-769662 but acted via a different mechanism involving Kv2.1 dephosphorylation. In cultured rat hippocampal neurons, A-769662 caused hyperpolarizing shifts in voltage gating similar to those in HEK293 cells, effects that were abolished by intracellular dialysis with Kv2.1 antibodies. When active thiophosphorylated AMPK was introduced into cultured neurons via the patch pipette, a progressive, time-dependent decrease in the frequency of evoked action potentials was observed. Our results suggest that activation of AMPK in neurons during conditions of metabolic stress exerts a protective role by reducing neuronal excitability and thus conserving energy.