Project description:Trans-10, cis-12 conjugated linoleic acid (t10c12 CLA) causes dramatic reductions in white adipose tissue in mice but has had limited effectiveness in humans. Determination of the signaling pathways involved may lead to better regulation of adiposity. T10c12 CLA was found to activate AMP-activating protein kinase (AMPK), a central regulator of cell metabolism. Compound C, a potent inhibitor of AMPK, prevents many of the typical responses to treatments with t10c12 CLA including the integrated stress response (ISR), the inflammatory response, the reduction in key lipogenic transcription factors, and delipidation. Treatment of adipocytes or mice with t10c12 CLA in conjunction with AMPK activator metformin results in more delipidation than treatment with the individual chemicals. Additionally, the combination showed a reduced inflammatory response relative to a t10c12 CLA treatment alone. The combination of t10c12 CLA and metformin, widely used to treat insulin resistance and Type II diabetes, has potential as a treatment for reducing adiposity in humans. Keywords: control/treatment Mouse 3T3-L1 RNA for was isolated from control linoleic acid (LA) and treatment (CLA, CLA+metformin, metformin) samples for analysis on microarrays with three biological reps.
Project description:Trans-10, cis-12 conjugated linoleic acid (t10c12 CLA) causes dramatic reductions in white adipose tissue in mice but has had limited effectiveness in humans. Determination of the signaling pathways involved may lead to better regulation of adiposity. T10c12 CLA was found to activate AMP-activating protein kinase (AMPK), a central regulator of cell metabolism. Compound C, a potent inhibitor of AMPK, prevents many of the typical responses to treatments with t10c12 CLA including the integrated stress response (ISR), the inflammatory response, the reduction in key lipogenic transcription factors, and delipidation. Treatment of adipocytes or mice with t10c12 CLA in conjunction with AMPK activator metformin results in more delipidation than treatment with the individual chemicals. Additionally, the combination showed a reduced inflammatory response relative to a t10c12 CLA treatment alone. The combination of t10c12 CLA and metformin, widely used to treat insulin resistance and Type II diabetes, has potential as a treatment for reducing adiposity in humans. Keywords: control/treatment
Project description:Activated AMPK and prostaglandins are involved in the response to conjugated linoleic acid and are sufficient to cause lipid reductions in adipocytes. Trans-10, cis-12 conjugated linoleic acid (t10c12 CLA) reduces triglyceride levels in adipocytes. AMP-activated protein kinase (AMPK) was recently demonstrated to be involved in the emerging pathways regulating this response. This study investigated the role of AMPK and inflammation in lowering triglyceride levels by testing the following hypotheses: 1) A moderate activator of AMPK, such as metformin, and an inflammatory response are sufficient to reduce triglycerides, and 2) Strong activation of AMPK is also sufficient. These experiments were performed by adding compounds that affect these pathways and measuring their effects in 3T3-L1 adipocytes. Tumor necrosis factor α (TNF-α), an inflammatory cytokine, increased the ability of metformin to reduce triglycerides, but TNF-α was observed to activate AMPK. A comparison of metformin, phenformin, TNF-α, and t10c12 CLA found a correlation between AMPK activity level and triglyceride reduction. Inhibitors of the prostaglandin (PG) biosynthetic pathway interfered with t10c12 CLA's ability to reduce triglycerides. Inhibitors of MAPK/ERK kinase or Jun N-terminal kinase interfered with the phosphorylation of phospholipase A2 and triglyceride reductions. Keywords: control/treatment Mouse 3T3-L1 RNA was isolated from control (LA) and treatment (CLA, phenformin) samples for analysis on microarrays with three biological replicates per sample. Limma data are available in the Supplementary files 'GSE17404_limma_CLAvsLA.txt', 'GSE17404_limma_PFMvsLA.txt', and 'GSE17404_limma_PFMvsCLA.txt'.
Project description:Activated AMPK and prostaglandins are involved in the response to conjugated linoleic acid and are sufficient to cause lipid reductions in adipocytes. Trans-10, cis-12 conjugated linoleic acid (t10c12 CLA) reduces triglyceride levels in adipocytes. AMP-activated protein kinase (AMPK) was recently demonstrated to be involved in the emerging pathways regulating this response. This study investigated the role of AMPK and inflammation in lowering triglyceride levels by testing the following hypotheses: 1) A moderate activator of AMPK, such as metformin, and an inflammatory response are sufficient to reduce triglycerides, and 2) Strong activation of AMPK is also sufficient. These experiments were performed by adding compounds that affect these pathways and measuring their effects in 3T3-L1 adipocytes. Tumor necrosis factor α (TNF-α), an inflammatory cytokine, increased the ability of metformin to reduce triglycerides, but TNF-α was observed to activate AMPK. A comparison of metformin, phenformin, TNF-α, and t10c12 CLA found a correlation between AMPK activity level and triglyceride reduction. Inhibitors of the prostaglandin (PG) biosynthetic pathway interfered with t10c12 CLA's ability to reduce triglycerides. Inhibitors of MAPK/ERK kinase or Jun N-terminal kinase interfered with the phosphorylation of phospholipase A2 and triglyceride reductions. Keywords: control/treatment
Project description:Inflammation, oxidative and dicarbonyl stress play important roles in the pathophysiology of type 2 diabetes. Metformin is the first-line drug of choice for the treatment of type 2 diabetes because it effectively suppresses gluconeogenesis in the liver, however, its “pleiotropic“ effects remain controversial. In the current study, we tested the effects of metformin on inflammation, oxidative and dicarbonyl stress in an animal model of inflammation and metabolic syndrome, the spontaneously hypertensive rat transgenically expressing human C-reactive protein (SHR-CRP). In the SHR-CRP transgenic strain, we found that metformin treatment decreased circulating levels of inflammatory response marker IL6 while levels of human CRP remained unchanged and metformin also significantly reduced oxidative stress (levels of conjugated dienes and TBARS) in the liver while no significant effects were observed in SHR control rats. In addition, in the presence of high human CRP, metformin reduced methylglyoxal levels in left ventricles but not in kidneys. Finally, metformin treatment reduced adipose tissue lipolysis. Possible molecular mechanisms of metformin action studied by gene expression profiling in the liver revealed deregulated genes from inflammatory, insulin signaling, AMP-activated protein kinase (AMPK) signaling and gluconeogenesis pathways. It can be concluded that in the presence of high levels of human CRP metformin protects against inflammation, oxidative and dicarbonyl stress in the heart and ameliorates insulin resistance and dyslipidemia.
Project description:Metformin is the front-line treatment for type 2 diabetes worldwide. It acts via effects on glucose and lipid metabolism in metabolic tissues, leading to enhanced insulin sensitivity. Despite significant effort, the molecular basis for metformin response remains poorly understood, with a limited number of specific biochemical pathways studied to date. To broaden our understanding of hepatic metformin response, we combine phospho-protein enrichment in tissue from genetically engineered mice with a quantitative proteomics platform to enable the discovery and quantification of basophilic kinase substrates in-vivo. We define proteins that binding to 14-3-3 are acutely regulated by metformin treatment and/or loss of the serine/threonine kinase, LKB1. Inducible binding of 250 proteins following metformin treatment is observed, 44% LKB1-dependent. Beyond AMPK, metformin activates Protein Kinase D and MAPKAPK2 in an LKB1-independent manner, revealing additional kinases that may mediate aspects of metformin response. Deeper analysis uncovered substrates of AMPK in endocytosis and calcium homeostasis.
Project description:Genes related to AMPK activation, cellular respiration, and metabolism are enriched in the gastric parietal cell population. Metformin is known activator of AMPK. We used microarray analysis to identify metformin targets in mature parietal cells and in parietal cell progenitors.
Project description:Despite being the frontline therapy for Type 2 diabetes, the mechanisms of action of the biguanide drug metformin are still being discovered. In particular, the detailed molecular interplays between the AMPK and the mTORC1 pathway in the hepatic benefits of metformin are still ill-defined. Metformin-dependent activation of AMPK classically inhibits mTORC1 via TSC/RHEB. But several lines of evidence suggest additional mechanisms at play in metformin inhibition of mTORC1. Here we investigated the role of direct AMPK-mediated serine phosphorylation of RAPTOR in a new RaptorAA mouse model, in which AMPK phospho-serine sites Ser722 and Ser792 of RAPTOR were mutated to alanine. Metformin treatment of intact murine liver requires AMPK regulation of both RAPTOR and TSC2 to fully inhibit mTORC1, and this regulation is critical for the transcriptional response to metformin. Transcriptionally, AMPK and mTORC1 were both important for regulation of anabolic metabolism and inflammatory programs triggered by metformin treatment. The hepatic transcriptional response in mice on high fat diet treated with metformin was largely ablated by AMPK-deficiency under the conditions examined, indicating the essential role of this kinase and its targets in metformin action in vivo.