AMPK：细胞能量中枢

腺苷酸活化蛋白激酶（AMP activated protein kinase,AMPK）是真核细胞中高度保守的丝氨酸／苏氨酸蛋白激酶,以异源三聚体的形式广泛存在于真核生物体内,是细胞的能量感受器,在能量代谢调控中起极其重要的作用。肝激酶B1（LKB1）、Ca^2＋／CaM-依赖蛋白激酶激酶β（CaMKKβ）、AMP／ATP或ADP／ATP比值升高以及诸如运动肌肉收缩等生理刺激均可以激活AMPK,进而调节细胞的能量代谢网络,提高其应对内外环境变化的能力,从而维持细胞水平乃至整个机体的稳定状态。活化的AMPK可以增强分解代谢,抑制合成代谢,上调ATP水平,参与细胞糖代谢、脂肪代谢、蛋白质代谢等能量代谢过程,增加细胞能量储备,应对能量缺乏。同时活化的AMPK参与细胞的生长、增殖、凋亡、自噬等基本生物学过程。AMPK是研究肥胖,糖尿病等能量代谢性疾病的核心。肿瘤细胞存在特殊的能量代谢方式,其发生,生长,转移与能量代谢失衡密切相关。AMPK与肿瘤细胞异常的能量代谢相关,为肿瘤发生、发展机制研究提供新的策略。本文主要探讨AMPK的结构、激活机制、参与的物质能量代谢和细胞的基本生物学过程以及与肿瘤发生的关联。     

天然AMPK激活剂防治代谢综合征的研究进展

能量代谢紊乱是代谢综合征产生的根本原因。AMPK(AMP-activated protein kinase)作为细胞乃至整个机体的能量调节器在能量较低的状态下被激活,促进分解代谢,抑制合成代谢,从而恢复能量平衡状态。因此,AMPK有望成为防治代谢综合征的新型靶点。单纯的药物治疗代谢综合征难以达到理想效果,许多天然营养分子也具有激活AMPK的功效,提示营养干预可能成为缓解代谢综合征的另一种新型有效手段。     

AMPK在非小细胞肺癌发生发展中的研究进展

腺苷酸活化的蛋白激酶(AMP activated protein kinase,AMPK),是细胞内重要的能量感受器,在调控细胞和机体的能量代谢中起到极其重要的作用。活化的AMPK可以增强分解代谢,抑制合成代谢,应对细胞内外环境的刺激。并且影响细胞的生长、增殖、凋亡、自噬等基本生物学过程。肿瘤细胞具有独特的能量代谢方式——Warburg现象,用于应对营养和能量的相对缺乏。AMPK干扰肿瘤细胞的独特能量代谢方式,广泛影响肿瘤的发生、生长、转移,发挥重要的肿瘤拮抗作用。非小细胞肺癌(non-small cell cancer,NSCLC)是常见恶性肿瘤的一种,具有一般恶性肿瘤的特征,近年来在NSCLC的研究进程表明:AMPK及其相关信号分子LKB1,PI3K/AKT,Ca MKKβ,PTEN等与NSCLC密切相关,活化相应通路或抑制相应通路,可显著拮抗NSCLC。从而AMPK及其相关信号分子有可能作为抗NSCLC药物的作用靶点。     

AMPK相关代谢机制在非创伤性股骨头坏死中的研究进展

腺苷酸活化的蛋白激酶(AMP-activated protein kinase, AMPK)作为"人体物质能量的调节器",在肥胖症、糖尿病、高脂血症等人体代谢性疾病中起着重要的调节作用。近年来研究表明AMPK信号通路对成骨成脂分化、破骨等人体骨稳态代谢微环境具有调控作用,而骨稳态代谢微环境的失衡失调是骨质疏松症、股骨头坏死等骨病发生的重要原因之一。本文主要通过对AMPK结构、功能及其在人体脂代谢、骨代谢中的作用机制进行探讨,探析其在骨病形成中的作用,并探析其在非创伤性股骨头坏死(non-traumatic osteonecrosis of the femoral head, NONFH)中的可能作用机制,从而为NONFH的研究及靶向治疗提供理论依据。     

新疆维吾尔族人2型糖尿病患者AMPK α2基因多态性的分析研究

目的:研究腺苷酸活化蛋白激酶(AMP-activated protein kinase,AMPK)单核苷酸多态性(SNPs)rs2143754位点与新疆地区维吾尔族人2型糖尿病之间的关系.方法:以聚合酶链式反应-限制性内切酶长度多态性(polymerase chain reaction-restriction frag-ment length polymorphism,PCR-RFLP)技术,对150例2型糖尿病和150例正常对照者AMPK-rs2143754位点进行基因分型.结果:AMPKα2位T/T、G/T和G/G基因型频率在病例组为(40%,51%和9%),正常对照组为(28%,49%和29%),两组基因型和等位基因频率分布差异有显著性(P<0.05).结论:AMPKα2多态性与新疆维吾尔族人2型糖尿病有明显相关性.     

AMPK在机体骨骼肌运动代谢适应方面的研究进展

腺苷酸活化蛋白激酶(AMP-activated protein kinase,AMPK)作为机体细胞的"能量感受器",可通过激活其下游靶蛋白调节组织细胞糖、脂代谢过程。运动适应涉及机体多个系统和器官,其中骨骼肌在机体对运动产生的代谢适应方面的作用最为明显。运动作为对机体的一个刺激可活化组织细胞AMPK,本文将针对AMPK在机体组织对运动产生代谢适应方面的最新研究进展加以综述,以期为阐明运动防治代谢性疾病的机制提供理论依据。     

AMPK α及p-AMPK α在运动过程中不同纤维类型骨骼肌中的表达变化

目的:检测腺苷酸活化蛋白激酶α(AMPKα)及磷酸化腺苷酸活化蛋白激酶α(p-AMPKα)在运动过程中不同纤维类型骨骼肌中的表达变化。方法:雄性C57BL/6小鼠随机分为对照组(运动前)、运功中(运动1 h后)和耗竭组(n=6)。放入跑台以15m/min的速度分别在运动前、运动1 h后及运动耗竭后取各组小鼠腓肠肌、比目鱼肌和跖肌。利用Western blot检测AMPKα及p-AMPKα的表达变化。结果:p-AMPKα在运动中及耗竭组腓肠肌、比目鱼肌和跖肌中持续高表达,尤其以比目鱼肌中表达变化最为显著。结论:p-AMPKα在运动过程中骨骼肌中的表达与肌纤维类型有关。     

新疆维吾尔族人2型糖尿病患者AMPKα2基因多态性的分析研究

目的：研究腺苷酸活化蛋白激酶（AMP-activated protein kinase,AMPK）单核苷酸多态性（SNPs）rs2143754位点与新疆地区维吾尔族人2型糖尿病之间的关系。方法：以聚合酶链式反应-限制性内切酶长度多态性（polymerase chain reaction-restriction flagmerit length polymorphism,PCR-RFLP）技术,对150例2型糖尿病和150例正常对照者AMPK-rs2143754位点进行基因分型。结果：AMPKet2位点T／T、G／T和G／G基因型频率在病例组为（40％,51％和9％）,正常对照组为（28％,49％和29％）,两组基因型和等位基因频率分布差异有显著性（P〈0．05）。结论：AMPKα2多态性与新疆维吾尔族人2型糖尿病有明显相关性。     

Activation of the prolyl-hydroxylase oxygen-sensing signal cascade leads to AMPK activation in cardiomyocytes

The proline hydroxylase domain-containing enzymes (PHD) act as cellular oxygen sensors and initiate a hypoxic signal cascade to induce a range of cellular responses to hypoxia especially in the aspect of energy and metabolic homeostasis regulation. AMP-activated protein kinase (AMPK) is recognized as a major energetic sensor and regulator of cardiac metabolism. However, the effect of PHD signal on AMPK has never been studied before. A PHD inhibitor (PHI), dimethyloxalylglycine and PHD2-specific RNA interference (RNAi) have been used to activate PHD signalling in neonatal rat cardiomyocytes. Both PHI and PHD2-RNAi activated AMPK pathway in cardiomyocytes effectively. In addition, the increased glucose uptake during normoxia and enhanced myocyte viability during hypoxia induced by PHI pretreatment were abrogated substantially upon AMPK inhibition with an adenoviral vector expressing a dominant negative mutant of AMPK-α1. Furthermore, chelation of intracellular Ca2+ by BAPTA, inhibition of calmodulin-dependent kinase kinase (CaMKK) with STO-609, or RNAi-mediated down-regulation of CaMKK α inhibited PHI-induced AMPK activation significantly. In contrast, down-regulation of LKB1 with adenoviruses expressing the dominant negative form did not affect PHI-induced AMPK activation. We establish for the first time that activation of PHD signal cascade can activate AMPK pathway mainly through a Ca(2+)/CaMKK-dependent mechanism in cardiomyocytes. Furthermore, activation of AMPK plays an essential role in hypoxic protective responses induced by PHI.     

Glucose deprivation accelerates VLDL receptor-mediated TG-rich lipoprotein uptake by AMPK activation in skeletal muscle cells

Glucose and fatty acids are major energy sources in skeletal muscle. Very low-density lipoprotein receptor (VLDL-R), which is highly expressed in heart, skeletal muscle and adipose tissue, plays a crucial role in metabolism of triglyceride (TG)-rich lipoproteins. To explore energy switching between glucose and fatty acids, we studied expression of VLDL-R and lipoprotein uptake in rat L6 myoblasts. l-Glucose or d-glucose deprivation in the medium noticeably induced the AMPK (AMP-activated protein kinase) activation and VLDL-R expression. Dose-dependent induction of VLDL-R expression was observed when d-glucose was less than 4.2 mM. The same phenomenon was also observed in rat primary skeletal myoblasts and cultured vascular smooth muscle cells. The uptake of β-VLDL but not LDL was accompanied by induction of VLDL-R expression. Our study suggests that the VLDL-R-mediated uptake of TG-rich lipoproteins might compensate for glucose shortfall through AMPK activation in skeletal muscle.     

AMP-activated protein kinase kinase: detection with recombinant AMPK alpha1 subunit

The AMP-activated protein kinase (AMPK) is a heterotrimeric serine/threonine protein kinase important for the responses to metabolic stress. It consists of a catalytic alpha subunit and two non-catalytic subunits, beta and gamma, and is regulated both by the allosteric action of AMP and by phosphorylation of the alpha and beta subunits catalyzed by AMPKK(s) and autophosphorylation. The Thr172 site on the alpha subunit has been previously characterized as an activating phosphorylation site. Using bacterially expressed AMPK alpha1 subunit proteins, we have explored the role of Thr172-directed AMPKKs in alpha subunit regulation. Recombinant alpha1 subunit proteins, representing the N-terminus, have been expressed as maltose binding protein (MBP) 6x His fusion proteins and purified to homogeneity by Ni(2+) chromatography. Both wild-type alpha1(1-312) and alpha1(1-312)T172D are inactive when expressed in bacteria, but the former can be fully phosphorylated (1 mol/mol) on Thr172 and activated by a surrogate AMPKK, CaMKKbeta. The corresponding AMPKalpha1(1-392), an alpha construct containing its autoinhibitory sequence, can be similarly phosphorylated, but it remains inactive. In an insulinoma cell line, either low glucose or 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR) treatment leads to activation and T172 phosphorylation of endogenous AMPK. Under the same conditions of cell incubation, we have identified an AMPKK activity that both phosphorylates and activates the recombinant alpha1(1-312), but this Thr172-directed AMPKK activity is unaltered by low glucose or AICAR, indicating that it is constitutively active.     

Low-Dose Sorafenib Acts as a Mitochondrial Uncoupler and Ameliorates Nonalcoholic Steatohepatitis

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AMPK signalling: Implications for podocyte biology in diabetic nephropathy

Diabetic nephropathy is a major long‐term complication of diabetes mellitus and one of the most common causes of end‐stage renal disease. Thickening of the glomerular basement membrane, glomerular cell hypertrophy and podocyte loss are among the main pathological changes that occur during diabetic nephropathy, resulting in proteinuria. Injury to podocytes, which are a crucial component of the glomerular filtration barrier, seems to play a key role in the development of diabetic nephropathy. Recent studies have suggested that dysregulation of AMP‐activated kinase protein, which is an essential cellular energy sensor, may play a fundamental role in this process. The purpose of this review is to highlight the molecular mechanisms associated with AMP‐activated protein kinase (AMPK) in podocytes that are involved in the pathogenesis of diabetic nephropathy.     

Anthraquinones from Morinda longissima and their insulin mimetic activities via AMP-activated protein kinase (AMPK) activation

AMP-activated protein kinase (AMPK) activators are known to increase energy metabolism and to reduce body weight, as well as to improve glucose uptake. During for searching AMPK activators, a new anthraquinone, modasima A (10), along with eighteen known analogues (1–9 and 11–19) were isolated from an ethanol extract of the roots of Morinda longissima Y. Z. Ruan (Rubiaceae). Using the fluorescent tagged glucose analogues, 2-(N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino)-2-deoxy-D-glucose (2-NBDG), insulin mimetics were screened with compounds 1–19 in 3T3-L1 adipocytes. Among them, compounds 2, 8 and 10 enhanced significantly glucose uptake into adipocytes and up-regulated the phosphorylated AMPK (Thr¹⁷²) whereas the glucose uptake enhancing activities of compounds 2, 8 and 10 were abrogated by treatment of compound C, an AMPK inhibitor. Taken together, these anthraquinones showed the potential action as insulin mimetic to improve glucose uptake via activation of AMPK.     

AMPK inhibition in health and disease

All living organisms depend on dynamic mechanisms that repeatedly reassess the status of amassed energy, in order to adapt energy supply to demand. The AMP-activated protein kinase (AMPK) αβγ heterotrimer has emerged as an important integrator of signals managing energy balance. Control of AMPK activity involves allosteric AMP and ATP regulation, auto-inhibitory features and phosphorylation of its catalytic (α) and regulatory (β and γ) subunits. AMPK has a prominent role not only as a peripheral sensor but also in the central nervous system as a multifunctional metabolic regulator. AMPK represents an ideal second messenger for reporting cellular energy state. For this reason, activated AMPK acts as a protective response to energy stress in numerous systems. However, AMPK inhibition also actively participates in the control of whole body energy homeostasis. In this review, we discuss recent findings that support the role and function of AMPK inhibition under physiological and pathological states.