AMPK对线粒体功能的调节

5’单磷酸腺苷活化蛋白激酶（AMP—activated protein kinase,AMPK）是细胞的能量感受器,调节细胞能量代谢,在正常细胞和癌细胞中均发挥重要的生物功能,它的激活有助于纠正代谢紊乱,使细胞代谢趋向生理平衡。在细胞应急反应中,细胞感受到能量危机,ATP浓度下降,AMP浓度上升,细胞内AMP／ATP比例上升,AMPK被激活：而在病理状态下,如代谢综合征、肿瘤等,常伴随能量代谢紊乱和AMPK激活抑制,因此,AMPK被视为治疗代谢性疾病与肿瘤的潜在作用靶点。然而,AMPK对能量代谢的调节与线粒体的功能密不可分,线粒体作为细胞的能量工厂,在健康与疾病中也发挥着重要的作用。越来越多的研究表明,线粒体能影响AMPK的活性,同时AMPK也通过多方面对线粒体进行调节,线粒体相关疾病与AMPK的调节有着密切的关系。该文主要针对AMPK是如何对线粒体的合成、线粒体自噬、内源性凋亡及线粒体相关疾病等方面进行综述。     

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的功能调控及其与肿瘤之间的关系

AMP激活的蛋白激酶(AMP activated protein kinase,AMPK)是高度保守的丝氨酸/苏氨酸蛋白激酶,广泛存在于真核生物中,是细胞内重要的能量感受器,具有调控和维持能量动态平衡的作用。在低能量状态下,活化的AMPK可增强机体的分解代谢,抑制合成代谢,并参与细胞生长、增殖、自噬等生物学功能,进而维持ATP产量以应对内外环境的变化。鉴于肿瘤细胞的生长与异常的能量代谢息息相关,AMPK可随细胞内特定能量条件的变化而变化,具有促进或抑制肿瘤发生的"双重功能"。本文综述了AMPK的生物学功能以及与肿瘤之间关系的进展,旨在为今后利用AMPK治疗代谢性疾病和预防肿瘤发生提供理论基础。     

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。     

腺苷酸活化蛋白激酶参与调控物质代谢及多种病理反应的分子机制

腺苷酸活化蛋白激酶(AMPK)在真核细胞生物中广泛存在,属于丝氨酸/苏氨酸蛋白激酶,是一个参与许多细胞信号传导通路的关键蛋白,也是调节细胞能量代谢的开关,故有细胞能量调节器之称。各种导致细胞内AMP/ATP比值升高的因素均可引起AMPK活化。AMPK活化是抑制消耗ATP的合成代谢并启动生成ATP的分解代谢的过程,从而维持机体能量代谢平衡。AMPK不仅在糖脂代谢和心血管、呼吸系统、生殖系统、泌尿系统等病理反应中具有重要作用,而且在人类恶性肿瘤中也扮演着重要角色,对肿瘤细胞的增殖、生长、侵袭和转移具有复杂的调控作用。我们简要综述AMPK的生物学特性及其参与调控多种病理反应的作用机制。     

AMPK:细胞能量中枢

腺苷酸活化蛋白激酶(AMPactivated proteinkinase,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)、Ca2+/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。     

AMPK在胰岛素信号转导通路中的作用

单磷酸腺苷活化蛋白激酶(AMP-activated potein kinase,AMPK)作为一种细胞能量调节器,当细胞经历代谢应激反应时,伴随着细胞内AMP水平或AMP与ATP的比例升高,AMPK被AMP激活,其活化的结果导致脂肪酸氧化的增加以产生更多ATP;同时,抑制ATP消耗,综合效应是帮助细胞度过急性损伤,暂时保障细胞的存活。因为一些治疗2型糖尿病的药物通过激活AMPK而发挥作用,故AMPK被认为是各种潜在的和有效的抗糖尿病药物的靶效应器。5-氨基-4-氨甲酰咪唑核苷(5-amino-4-imidazolecarboxamide riboside,AICAR),进入细胞后被磷酸化变成ZMP,后者类似AMP也能够激活AMPK。因此,我们采用AICAR激活AMPK,观察活化的AMPK对脂肪细胞能量代谢及胰岛素信号途径的作用。结果显示,脂肪细胞中的AMPK被激活后,丙酰辅酶A(malonyl-CoA,一种脂肪酸氧化作用的抑制剂及脂肪酸合成的前体中间产物)浓度下降80%;在已分化的3T3-F442a脂肪细胞中,AICAR通过激活AMPK,增强胰岛素对Akt/PKB的激活和GSK3的磷酸化。相反,在AICAR预...     

AMPK在机体糖脂代谢中的作用

AMP激活的蛋白激酶(AMPK)是一种广泛参与调节细胞代谢的激酶,被称为"能量感受器".一旦胞浆中AMP/ATP比例升高,或其它因素激活AMPK时,AMPK可增强葡萄糖摄取和利用,以及脂肪酸氧化,产生更多能量;同时抑制葡萄糖异生、脂质合成及糖原合成等通路,减少能量消耗,从而使细胞能量代谢保持平衡.AMPK参与调节包括胰岛β细胞、肝脏、骨骼肌和脂肪在内的多种外周组织的糖脂代谢过程.本文旨在总结并讨论AMPK在机体主要糖脂代谢器官中的作用,并重点分析其在治疗胰岛素抵抗和2型糖尿病中的潜在作用.     

下丘脑AMPK的活性介导摄食和体重调节

一磷酸腺苷(adenosine-monophosphate, AMP)活化的蛋白激酶(AMP-activated protein kinase,AMPK)是蛋白激酶级联反应的下游成分,是哺乳动物的细胞燃料计,也是细胞内的能量传感器,在维持能量平衡中占有重要作用。下丘脑是食物摄入和能量平衡的关键调节器,其AMPK参与的脂肪酸代谢途径不仅在调节食物摄入和能量平衡中发挥重要作用,也是外周激素信号如瘦素、胰岛素、脂联素和胃促生长素等作用的中介物。本文主要综述了下丘脑AMPK的活性调节及其整合外周激素信号参与能量稳态调节的机制,并展望了AMPK在体重调节和肥胖治疗中的作用。     

MELK的功能及其在肿瘤研究中的进展

母体胚胎亮氨酸拉链激酶(MELK)是蔗糖非发酵1/AMP活化蛋白激酶(Snf1/AMPK)家族中一个独特成员,是一种周期依赖性激酶。与家族其他成员不同,MELK并不参与代谢应激状态下细胞的生存调控,而更多参与细胞周期、细胞增殖、肿瘤生成和细胞凋亡等过程。MELK在人体多种肿瘤中表达升高,与肿瘤的预后密切相关。MELK在肿瘤干细胞中被异常激活,使肿瘤细胞获得生长、侵袭、迁移等能力,因此,MELK可以作为肿瘤治疗的重要靶点。我们就MELK基因的生物学功能、作用机制及其在肿瘤研究中的进展做简要综述。     

AMPK links energy status to cell structure and mitosis

AMP-activated protein kinase (AMPK) is known as an important cellular energy sensor, but its in vivo role has not been fully understood. Recent studies provided surprising results that AMPK regulates cell polarity and mitosis under the control of tumour suppressor LKB1. Moreover, these newly found in vivo functions of AMPK are regulated by energy status in a cell autonomous manner. These findings provide novel insights into the physiological function of AMPK and the treatment of AMPK-related diseases such as cancer and diabetes.     

Perspectives of the AMP-activated kinase (AMPK) signalling pathway in thyroid cancer

Approximately 90% of non-medullary thyroid malignancies originate from the follicular cell and are classified as papillary or follicular (well-differentiated) thyroid carcinomas, showing an overall favourable prognosis. However, recurrence or persistence of the disease occurs in some cases associated with the presence of loco-regional or distant metastatic lesions that generally become resistant to radioiodine therapy, while glucose uptake and metabolism are increased. Recent advances in the field of tumor progression have shown that CTC (circulating tumour cells) are metabolic and genetically heterogeneous. There is now special interest in unravelling the mechanisms that allow the reminiscence of dormant tumour lesions that might be related to late disease progression and increased risk of recurrence. AMPK (AMP-activated protein kinase) is activated by the depletion in cellular energy levels and allows adaptive changes in cell metabolism that are fundamental for cell survival in a stressful environment; nevertheless, the activation of this kinase also decreases cell proliferation rate and induces tumour cell apoptosis. In the thyroid field, AMPK emerged as a novel important intracellular pathway, since it regulates both iodide and glucose uptakes in normal thyroid cells. Furthermore, it has recently been demonstrated that the AMPK pathway is highly activated in papillary thyroid carcinomas, although the clinical significance of these findings remains elusive. Herein we review the current knowledge about the role of AMPK activation in thyroid physiology and pathophysiology, with special focus on thyroid cancer.     

AMP-activated protein kinase--the key role in metabolic regulation

AMP-activated protein kinase (AMPK) is the central component of a protein kinase cascade that acts as an energy sensor maintaining the energy balance at the cellular as well as at the whole body level. Within the healthy cell, metabolic stress leading to an increase in AMP concentration results in AMPK activation. Once activated, AMPK "switches off" many anabolic pathways e.g. fatty acid and protein synthesis while "switches on" catabolic pathways such as fatty acid oxidation or glycolysis which serve to restore intracellular ATP level. Adipocyte derived hormones leptin and adiponectin activate AMPK in peripheral tissues increasing energy expenditure. AMPK also regulates food intake due to response to hormonal and nutrient signals in hypothalamus. Antidiabetic drugs that mimic the action of insulin activate the AMPK signaling pathways. Further studies are needed to clarify the importance of the AMPK activation for therapeutic effects of this drugs.     

Therapeutic strategies targeting AMPK-dependent autophagy in cancer cells

Macroautophagy is a health-modifying process of engulfing misfolded or aggregated proteins or damaged organelles, coating these proteins or organelles into vesicles, fusion of vesicles with lysosomes to form autophagic lysosomes, and degradation of the encapsulated contents. It is also a self-rescue strategy in response to harsh environments and plays an essential role in cancer cells. AMP-activated protein kinase (AMPK) is the central pathway that regulates autophagy initiation and autophagosome formation by phosphorylating targets such as mTORC1 and unc-51 like activating kinase 1 (ULK1). AMPK is an evolutionarily conserved serine/threonine protein kinase that acts as an energy sensor in cells and regulates various metabolic processes, including those involved in cancer. The regulatory network of AMPK is complicated and can be regulated by multiple upstream factors, such as LKB1, AKT, PPAR, SIRT1, or noncoding RNAs. Currently, AMPK is being investigated as a novel target for anticancer therapies based on its role in macroautophagy regulation. Herein, we review the effects of AMPK-dependent autophagy on tumor cell survival and treatment strategies targeting AMPK.     

GHRH antagonist MZ-5-156 increases the expression of AMPK in A549 lung cancer cells

AMP-activated protein kinase (AMPK) regulates cellular proliferation, growth and metabolism. Targeted activation of AMPK is considered an important therapeutic strategy for cancer treatment. To evaluate the effect of growth hormone-releasing hormone (GHRH) and its antagonist MZ-5-156 on the phosphorylation of AMPK and other related regulatory intracellular proteins we employed human non-small cell lung cancer cell line A549, which expresses GHRH receptors. Treatment of A549 cells with GHRH antagonist decreased cell proliferation and activated AMPK as well as glycogen synthase kinase (GSK)3β. Furthermore, MZ-5-156 inhibited Akt, the mammalian target of rapamycin (mTOR) and its downstream target eIF4E which controls protein synthesis and cell growth. GHRH(1-29)NH2 counteracted all these effects. HeLa human endometrial cancer cells which do not express any GHRH receptors were used as a negative control and GHRH did not induce the AMPK activation in these cells. Our results demonstrate for the first time that GHRH antagonists can regulate the AMPK metabolic pathway, which is crucial for the growth of non-small cell lung cancer and other major cancers.     

Low levels of AMPK promote epithelial‐mesenchymal transition in lung cancer primarily through HDAC4‐ and HDAC5‐mediated metabolic reprogramming

AMP‐activated protein kinase (AMPK) serves as a “supermetabolic regulator” that helps maintain cellular energy homeostasis. However, the role of AMPK in glucose metabolism reprogramming in lung cancer remains unclear. Here, our study shows that low AMPK expression correlates with metastasis and clinicopathologic parameters of non–small‐cell lung cancer. Low AMPK significantly enhances the Warburg effect in HBE and A549 cells, which in turn induces the expression of mesenchymal markers and enhances their invasion and migration. At the mechanistic level, low AMPK up‐regulates HK2 expression and glycolysis levels through HDAC4 and HDAC5. Collectively, our findings demonstrate that low AMPK‐induced metabolism can promote epithelial‐mesenchymal transition progression in normal bronchial epithelial cells and lung cancer cells, and increase the risk for tumour metastasis.     

Opinion: alternative views of AMP-activated protein kinase

Genes most closely related to adenosine monophosphate (AMP)-activated protein kinase, including SAD kinases and Par-1 regulate cell polarity, although AMP-activated protein kinase (AMPK) modulates cellular energy status. LKB1 (Par-4) is required for normal activation of AMPK in the liver and also regulates cell polarity. AMPK is proposed to inhibit energy consuming activity while initiating energy producing activity during energy limitation. Demonstration that metformin, a common drug for Type 2 diabetes, requires LKB1 for full therapeutic benefit has increased interest in AMPK signaling. Despite the potential importance of AMPK signaling for diabetes, metabolic syndrome and even cancer, the developmental processes regulated by AMPK in genetically mutant animals require further elucidation. Mouse conditional null mutants for AMPK activity will allow genetic elucidation of AMPK function in vivo. This perspective focuses on sequence and structural moieties of AMPK and genetic analysis of AMPK mutations. Interestingly, the predicted protein structure of the carboxy-terminus of AMPKα resembles the carboxy-terminal KA-1 domain of MARK3, a Par-1 orthologue.     

Hsp90 interacts with AMPK and mediates acetyl-CoA carboxylase phosphorylation

Heat shock protein 90 (Hsp90) serves to stabilise and correctly fold multiple significant client proteins associated with cell proliferation and cell survival. However, little is known about the Hsp90 client proteins that regulate cell metabolism. Here, we describe a unique ability of Hsp90 to regulate the stability and activity of AMP-activated kinase (AMPK), a key sensor of cellular energy status. Hsp90 is found to interact with AMPK and to maintain its AMP-activated kinase activity, which in turn is required for the phosphorylation of its substrate, acetyl-CoA carboxylase (ACC), the key enzyme in fatty acid metabolism. Our binding analysis reveals that both the γ subunit and the α subunit of AMPK bind to Hsp90 with a high affinity. We demonstrate that Hsp90 inhibitors, including geldanamycin (GA) and mycoepoxydiene (MED), can induce the dissociation of AMPK from Hsp90, and cause a significant decrease in phosphorylation of AMPK and ACC. Furthermore, we demonstrate that shRNAs of Hsp90 can efficiently suppress the activation of AMPK. These findings not only establish a novel interaction between Hsp90 and AMPK but also suggest a new mechanism for regulating tumour cell fatty acid metabolism.     

AMPKα2 knockout enhances tumour inflammation through exacerbated liver injury and energy deprivation‐associated AMPKα1 activation

Tissue damage and its associated‐inflammation act as tumour initiators or propagators. AMP‐activated protein kinase (AMPK) is activated by environmental or nutritional stress factors, such as hypoxia, glucose deprivation, and other cell injury factors, to regulate cell energy balance and differentiation. We previously have reported that AMPKα2 deficiency resulted in the energy deprivation in tumour‐bearing liver and the enhanced‐hepatocyte death. In this study, AMPKα2 knockout mice and the liver metastasis model of colon cancer cells were used to address the role of AMPKα isoforms in tumour inflammation. First, we found that the AMPKα2 deficiency exacerbated the liver injury and recruitment of macrophages. Meanwhile, although compensatory expression of AMPKα1 was not significant after AMPKα2 knockout, AMPKα1 phosphorylation was elevated in remnant liver in AMPKα2 knockout mice, which was positively associated with the enhanced energy deprivation in the AMPKα2 deficient mice. Furthermore, the activated AMPKα1 in macrophage contributed to its polarizing to tumour‐associated phenotype. Thus, the enhanced tumour‐associated inflammation and activation of AMPKα1 in the AMPKα2 deficient mice may exacerbate the tumour development by affecting the tumour inflammatory microenvironment. Our study suggests that the two isoforms of AMPKα, AMPKα1 and AMPKα2 play different roles in controlling tumour development.     

Chutes and Ladders: the search for protein kinases that act on AMPK

AMP-activated protein kinase (AMPK), a key regulator of energy homeostasis in mammalian cells, is, in turn, regulated by long-sought upstream protein kinases (AMPKKs). Following the recent identification of the tumor-suppressor kinase LKB1 as an AMPKK, a broader role for AMPK in metabolic economy has been unveiled by a new body of work from three groups that implicates the Ca(2+)/calmodulin-dependent protein kinase kinases as AMPKKs. We suggest that PKE (protein kinase "energy" or "economy") is now an apt name for this kinase, which regulates both cellular and whole-organism energy homeostasis.