Project description:A longevity gene, sirtuin 1 (SIRT1) and energy sensor AMP-activated protein kinase (AMPK) have common activators such as caloric restriction, oxidative stress and exercise.The objective is to characterize the role of cardiomyocyte SIRT1 in age-related impaired ischemic AMPK activation and increased susceptibility to ischemic insults.
Project description:Steroid hormones regulate essential physiological processes and inadequate levels are associated with various pathological conditions. In testosterone-producing Leydig cells, steroidogenesis is strongly stimulated by LH via its receptor leading to increased cAMP production and expression of the steroidogenic acute regulatory (STAR) protein, which is essential for the initiation of steroidogenesis. Leydig cell steroidogenesis then passively decreases following the rapid degradation of cAMP into AMP by phosphodiesterases. In this study, we show that AMP-activated protein kinase (AMPK) is activated following cAMP breakdown in MA-10 and MLTC-1 Leydig cells. Activated AMPK then actively inhibits cAMP-induced steroidogenesis by repressing the expression of key regulators of steroidogenesis including Star and Nr4a1. Similar results were obtained in Y-1 adrenal cells and in the constitutive steroidogenic cell line R2C. Our data identify AMPK as an active repressor of steroid hormone biosynthesis in steroidogenic cells that is essential to preserve cellular energy and prevent excess steroid production. Steroid hormones regulate essential physiological processes and inadequate levels are associated with various pathological conditions. In testosterone-producing Leydig cells, steroidogenesis is strongly stimulated by LH via its receptor leading to increased cAMP production and expression of the steroidogenic acute regulatory (STAR) protein, which is essential for the initiation of steroidogenesis. Leydig cell steroidogenesis then passively decreases following the rapid degradation of cAMP into AMP by phosphodiesterases. In this study, we show that AMP-activated protein kinase (AMPK) is activated following cAMP breakdown in MA-10 and MLTC-1 Leydig cells. Activated AMPK then actively inhibits cAMP-induced steroidogenesis by repressing the expression of key regulators of steroidogenesis including Star and Nr4a1. Similar results were obtained in Y-1 adrenal cells and in the constitutive steroidogenic cell line R2C. Our data identify AMPK as an active repressor of steroid hormone biosynthesis in steroidogenic cells that is essential to preserve cellular energy and prevent excess steroid production. MA-10 Leydig cells were treated with either DMSO (control), 10 uM forskolin or forskolin+Aicar (1 mM) for 1.5 h before total RNA extraction
Project description:AMP-activated protein 1 kinase (AMPK), a phylogenetically conserved serine/threonine kinase regarded as a key cellular energy sensor, exists in eukaryotes as a heterotrimer comprising a catalytic α and regulatory β and γ subunits. In humans, activating mutations in the gene encoding the γ2 subunit of AMPK (PRKAG2) display a cardiac phenotype of left ventricular hypertrophy (LVH), conduction system disease, ventricular pre-excitation and increased cardiomyocyte glycogen accumulation. While existing transgenic models have elucidated the pathogenesis of several aspects of the disease5-7, the slow heart rate (sinus bradycardia) – a prominent feature of the disease – remains poorly understood. Here, using gene-targeting to generate mice which recapitulate this bradycardia, we demonstrate that γ2 AMPK activation perturbs fundamental mechanisms that determine sinoatrial pacemaker cell function. Reduction in the sarcolemmal hyperpolarization activated (“funny”) current (If) and damping of ryanodine receptor-derived diastolic local subsarcolemmal Ca2+ releases (LCRs)12,13 contribute to reduced sinoatrial cell spontaneous activity and, ultimately, to a lower heart rate. Pharmacological activation of AMPK reversibly reduces the beating rate of murine pluripotent stem cell-derived induced sinoatrial bodies. In contrast, using a mouse knock-out of γ2 AMPK, which exhibits an increased heart rate, we demonstrate a role for γ2 AMPK in physiological heart rate regulation, including an indispensable role in the bradycardic adaptation to endurance exercise. Through regulating the cardiac pacemaker and thereby heart rate, γ2 AMPK by virtue of its energy-sensing role, is a key physiological determinant of overall cardiac energy homeostasis.
Project description:Conducted serum untargeted metabolomics analysis in AMP-activated protein kinase (AMPK) intestinal KO mice and control mice under high-fat diet (HFD) conditions
Project description:To explore the function of AMPK signaling in acute myeloid leukemia (AML), we used shRNA to knock down the expression of PRKAA1, the catalytic subunit of the 5'-prime-AMP-activated protein kinase (AMPK), in primary human AML cells and performed RNA-seq experiment to profile transcriptional changes upon AMPK inactivation.
Project description:AMP-activated protein kinase (AMPK) is a major regulator of cellular energy homeostasis that coordinates metabolic pathways in order to balance nutrient supply with energy demand. AMPK elicits acute and diverse metabolic effects by directly phosphorylating various targets. AMPK activation also promotes metabolic reprogramming in longer term via effects on gene expression. The aim of this study is to elucidate molecular mechanism(s) by which AMPK activation modulates metabolic adaptation through its impact on gene regulation.
Project description:The conserved Snf1/AMPK (AMP-activated protein Kinase) family is one of the central components in nutrient sensing and regulation of carbon metabolism in eukaryotes. It is also involved in several other processes such as stress resistance, invasive growth and ageing. Snf1 kinase is composed of a catalytic alpha-subunit Snf1, a regulatory gamma-subunit Snf4 and one of three possible beta-subunits, Sip1, Sip2 or Gal83. We used a systematic approach to study the role of the three beta-subunits by analyzing all 7 possible combinations of beta-subunit deletions together with the reference strain.
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'.