AMP-activated protein kinase (AMPK) is a central regulator of energy homeostasis, which coordinates metabolic pathways and thus balances nutrient supply with energy demand. Because of the favorable physiological outcomes of AMPK activation on metabolism, AMPK has been considered to be an important therapeutic target for controlling human diseases including metabolic syndrome and cancer. Thus, activators of AMPK may have potential as novel therapeutics for these diseases. In this review, we provide a comprehensive summary of both indirect and direct AMPK activators and their modes of action in relation to the structure of AMPK. We discuss the functional differences among isoform-specific AMPK complexes and their significance regarding the development of novel AMPK activators and the potential for combining different AMPK activators in the treatment of human disease.
AMP-Activated Protein Kinases* ; Homeostasis ; Humans ; Metabolic Networks and Pathways ; Metabolism

AMP-activated protein kinase (AMPK) is a central regulator of energy homeostasis, which coordinates metabolic pathways and thus balances nutrient supply with energy demand. Because of the favorable physiological outcomes of AMPK activation on metabolism, AMPK has been considered to be an important therapeutic target for controlling human diseases including metabolic syndrome and cancer. Thus, activators of AMPK may have potential as novel therapeutics for these diseases. In this review, we provide a comprehensive summary of both indirect and direct AMPK activators and their modes of action in relation to the structure of AMPK. We discuss the functional differences among isoform-specific AMPK complexes and their significance regarding the development of novel AMPK activators and the potential for combining different AMPK activators in the treatment of human disease.
AMP-Activated Protein Kinases* ; Homeostasis ; Humans ; Metabolic Networks and Pathways ; Metabolism

AMP-Activated Protein Kinases/metabolism* ; Adenosine Monophosphate/metabolism* ; Kidney/metabolism* ; Phosphorylation

Simiao Wan (SMW) is a traditional Chinese formula, including Atractylodis Rhizoma, Achyranthis Bidentatae Radix, Phellodendri Chinensis Cortex and Coicis Semen at the ratio of 1:1:2:2. It can be used to the treatment of diabetes. However, its bioactive compounds and underlying mechanism are unclear. This study aimed to screen the antilipolytic fraction from SMW and investigate its therapeutic mechanisms on hepatic insulin resistance. Different fractions of SMW were prepared by membrane separation combined with macroporous resin and their antilipolytic activities were screened in fasted mice. The effects of 60% ethanol elution (ESMW) on lipolysis were investigated in 3T3-L1 adipocytes stimulated by palmitic acid (PA) and high fat diet (HFD)-fed mice. In our study, ESMW is the bioactive fraction responsible for the antilipolytic activity of SMW and 13 compounds were characterized from ESMW by UHPLC-QTOF-MS/MS. ESMW suppressed protein kinase A (PKA)-hormone-sensitive lipase (HSL) related lipolysis and increased AMP-activated protein kinase (AMPK) phosphorylation in PA challenged 3T3-L1 adipocytes. AMPKα knockdown abolished the inhibitory effects of ESMW on IL-6 and HSL pSer-660, revealing that the antilipolytic and anti-inflammatory activities of ESMW are AMPK dependent. Furthermore, ESMW ameliorated insulin resistance and suppressed lipolysis in HFD-fed mice. It inhibited diacylglycerol accumulation in the liver and inhibited hepatic gluconeogenesis. Conditional medium collected from ESMW-treated 3T3-L1 cells ameliorated insulin action on hepatic gluconeogenesis in liver cells, demonstrating the antilipolytic activity contributed to ESMW beneficial effects on hepatic glucose production. In conclusion, ESMW, as the antilipolytic fraction of SMW, inhibited PKA-HSL related lipolysis by activating AMPK, thus inhibiting diacylglycerol (DAG) accumulation in the liver and thereby improving insulin resistance and hepatic gluconeogenesis.
AMP-Activated Protein Kinases/metabolism* ; Animals ; Insulin/metabolism* ; Lipolysis/physiology* ; Liver/metabolism* ; Mice ; Tandem Mass Spectrometry

The AMP-activated protein kinase (AMPK) is a pivotal serine/threonine kinase participating in the regulation of glucose, lipid as well as protein metabolism and maintenance of energy homeostasis. Recent studies demonstrated that AMPK can also inhibit nuclear factor-κB, suppress the expression of inflammatory genes and attenuate inflammatory injury through phosphorylating its downstream targets including SIRT1, PGC-lα, p53 and FoxO3a. In addition, the widely used antidiabetic metformin also exerts its anti-inflammatory effects through activating AMPK. Therefore, AMPK is emerging as a promising novel target for the development of anti-inflammatory drugs. This review summarized the anti-inflammatory effects of AMPK and the underling molecular mechanisms.
AMP-Activated Protein Kinases ; metabolism ; Homeostasis ; Inflammation ; enzymology ; Metformin ; pharmacology ; NF-kappa B ; antagonists & inhibitors ; Phosphorylation

BACKGROUNDRecent studies on bone have shown an endocrine role of the skeleton, which could be impaired in various human diseases, including osteoporosis, obesity, and diabetes-associated bone diseases. As a sensor and regulator of energy metabolism, AMP-activated protein kinase (AMPK) may also play an important role in the regulation of bone metabolism. The current study aimed to establish the expression profiles and phosphorylation patterns of AMPK subunits in several mesenchymal cell types.

METHODSReverse transcription-polymerase chain reaction (PCR) for relative quantification, real-time PCR for absolute quantification, and Western blotting were used to investigate the gene expression profiles and phosphorylation patterns of AMPK subunits in several mesenchymal cell types, including primary human mesenchymal stem cells (hMSCs) and hFOB, Saos-2, C3H/10T1/2, MC3T3-E1, 3T3-L1, and C2C12 cells.

RESULTSAMPKα1 and AMPKβ1 mRNAs were abundantly expressed in all cell types. AMPKγ1 mRNA was abundantly expressed in C3H/10T1/2, MC3T3-E1, 3T3-L1, and C2C12 but not detected in human-derived cell types. AMPKγ2 mRNA was mildly expressed in all cell types. AMPKα1 protein was highly expressed in all cell types and AMPKα2 protein was highly expressed only in hFOB and Saos-2 cells. AMPKβ1 protein was abundantly expressed in all cell types except for Saos-2, in which AMPKβ2 protein overwhelmed AMPKβ1 expression. AMPKγ1 and AMPKγ2 proteins were expressed in C3H/10T1/2, MC3T3-E1, 3T3-L1, and C2C12 cells and only AMPKγ2 protein was expressed in hMSCs, hFOB and Saos-2 cells. AMPKα was phosphorylated at Thr172 and Ser485 and AMPKβ1 was phosphorylated at Ser108 and Ser182 in all cell types with a specific pattern in each cell type.

CONCLUSIONThe combination of AMPK α, β, and γ subunits and phosphorylation of AMPKα (Thr172 and Ser485) and AMPKβ1 (Ser108 and Ser182) showed a specific pattern in each cell type.

AMP-Activated Protein Kinases ; genetics ; metabolism ; Animals ; Cell Line ; Humans ; Mesenchymal Stromal Cells ; enzymology ; Mice ; Phosphorylation

ATP is an important energy source for cells. Traditionally, intracellular ATP levels are believed to be relatively stable and will not rise consistently in the physiological conditions. However, new studies suggest that ATP levels may rise in multiple tissues under the condition of energy surplus contributing to the metabolic disorders in obesity. However, the molecular mechanism of ATP elevation remains unknown in obesity except the increase in energy supply. Based on our experimental results and the findings reported in the literature, we discuss the cellular and molecular mechanisms by which ATP levels are regulated in cells by multiple factors, including superoxide ions, mitochondrial flash, antioxidants, anti-apoptotic molecule Bcl-xL, AMP-activated protein kinase (AMPK) and metformin. Contribution of these factors to the alteration of ATP set-point will be discussed together with their impact on insulin resistance in type 2 diabetes mellitus. With a focus on the energy surplus in obesity, we explore the mechanism of insulin resistance induced by ATP elevation and provide an answer to the contradiction between the new experimental results and the traditional viewpoint of intracellular ATP. We propose that elevation of intracellular ATP may lead to metabolic disorder in obesity through activation of a feedback mechanism that inhibits mitochondrial function.
AMP-Activated Protein Kinases ; Adenosine Triphosphate ; Diabetes Mellitus, Type 2 ; Energy Metabolism ; Humans ; Metformin ; Obesity

Sepsis-induced cardiac dysfunction is a serious complication of sepsis with no effective treatment. AMP-activated protein kinase (AMPK) is a regulator for energy metabolism in cells and plays a key role in the energy balance. Recent studies have shown that AMPK exerted a protective effect on sepsis-induced cardiac dysfunction, which was related to the regulation of inflammation, endothelial cells injury, energy metabolism, myocardial cells apoptosis and autophagy. Therefore, AMPK is a therapeutic target for sepsis-induced cardiac dysfunction.
AMP-Activated Protein Kinases ; metabolism ; Apoptosis ; Autophagy ; Heart Diseases ; enzymology ; etiology ; Humans ; Sepsis ; complications

Adenosine 5'-monophosphate-activated protein activated protein kinase (AMPK), a heterotrimeric complex, is an important kinase to regulate glycolipid metabolism and energy balance involved in a variety physiological processes in human body. Many research indicated that the function and activity of AMPK were closely related to inflammation, diabetes and cancers. Recent reports show that inhibition of metformin (a first-line drug) on hepatic glucose in patients with hyperglycemia is associated with AMPK pathway, suggesting that targeting AMPK may be one of the effective strategies for the prevention and treatment of a variety of chronic diseases. Here, we review research progress on the structure, activation and regulation of AMPK in glycolipid metabolism to provide an insight into the basic and clinical research of diabetes therapy.
AMP-Activated Protein Kinases ; Adenosine ; Adenosine Monophosphate ; Energy Metabolism ; Enzyme Activation ; Glycolipids ; Humans

Danzhi Xiaoyao Powder is a classical prescription for anxiety. This study aims to analyze the effect of this medicine on mitochondrial morphology and function of anxiety rats and explore the mechanism of it against anxiety. Specifically, uncertain empty bottle drinking water stimulation(21 days) was employed to induce anxiety in rats. The elevated plus-maze test and open field test were respectively performed on the 7 th, the 14 th, and the 21 st days of the stimulation, so as to detect the anxiety-related protein index brain-derived neurotrophic factor(BDNF) and evaluate the anxiety level of animals. On this basis, the effect of this prescription on anxiety rats was preliminarily evaluated. After the behavioral test on the 21 st day, rats were killed and the brain tissues were separated for the observation of the mitochondrial morphology and the determination of mitochondrial function-related indicators and the adenosine 5'-monophosphate-activated protein kinase(AMPK) level. The results showed that Danzhi Xiaoxiao Powder could alleviate the anxiety-like behavior of rats, significantly increase the percentage of time in open arm in elevated plus-maze test and the ration of activity time in the central area of the field, dose-dependently raise the activity levels of respiratory chain complex Ⅰ,Ⅱ,Ⅲ and Ⅳ and the adenosine triphosphate(ATP) content, and elevate the levels of BDNF and phosphorylated AMPK(p-AMPK). Clear structure and intact morphology of mitochondrial cristae in medial prefrontal cortex cells and amygdala were observed in the Danzhi Xiaoyao Powder group. In summary, Danzhi Xiaoyao Powder exerts therapeutic effect on anxiety, and the mechanism is the likelihood that p-AMPK protects the structure and maintains the function of mitochondria.
Rats ; Animals ; Brain-Derived Neurotrophic Factor/metabolism* ; Powders ; AMP-Activated Protein Kinases ; Anxiety/drug therapy* ; Mitochondria