Project description:Increased beta-cell senescence contributes to the development of type 2 diabetes (T2D). Exercise is critical in the treatment of T2D and can attenuate aging-associated cellular changes, but its effects on beta-cell senescence are unknown. Using two mouse models of insulin resistance, we showed that exercise prevented and reversed beta-cell senescence. Mechanistic studies revealed that these effects were mediated by exercise-induced increases in serum glucagon leading to AMPK activation in beta-cells. Nuclear translocation of NRF2 in mouse islets after exercise and its inversely proportional regulation of p16Ink4a, suggested its role as a molecular mediator between AMPK activation and cellular senescence.
Project description:Emerging evidence indicates that metabolic dysregulation drives prostate cancer (PCa) progression and metastasis. AMPK is a master regulator of metabolism although its role in PCa remains unclear. Here we show that genetic and pharmacological activation of AMPK provides a dramatic protective effect on PCa progression in vivo. We show that AMPK activation induces PGC1a expression leading to a catabolic metabolic reprogramming of PCa cells. This catabolic state is characterised by increased mitochondrial gene expression, increased fatty acid oxidation, decreased lipogenic potential, decreased cell proliferation and decreased cell invasiveness. Together, these changes inhibit PCa disease progression. Additionally, we identify a gene network that is inhibited by AMPK activation involved in cell cycle regulation. We show correlation between this gene network and PGC1a expression in human PCa. Taken together our findings strongly support the use of AMPK activators for clinical treatment of PCa.
Project description:Emerging evidence indicates that metabolic dysregulation drives prostate cancer (PCa) progression and metastasis. AMPK is a master regulator of metabolism although its role in PCa remains unclear. Here we show that genetic and pharmacological activation of AMPK provides a dramatic protective effect on PCa progression in vivo. We show that AMPK activation induces PGC1-alpha expression leading to a catabolic metabolic reprogramming of PCa cells. This catabolic state is characterised by increased mitochondrial gene expression, increased fatty acid oxidation, decreased lipogenic potential, decreased cell proliferation and decreased cell invasiveness. Together, these changes inhibit PCa disease progression. Additionally, we identify a gene network involved in cell cycle regulation that is inhibited by AMPK activation. Strikingly, we show a strong correlation between this gene network and PGC1-alpha gene expression in human PCa. Taken together our findings strongly support the use of AMPK activators for clinical treatment of PCa to improve patient outcome.
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:Despite significant advances in our understanding of the biology determining systemic energy homeostasis, the treatment of obesity remains a medical challenge. Activation of AMP-activated protein kinase (AMPK) has been proposed as an attractive strategy for the treatment of obesity and its complications. AMPK is a conserved, ubiquitously expressed, heterotrimeric serine/threonine kinase whose short-term activation has multiple beneficial metabolic effects. Whether these translate into long-term benefits for obesity and its complications is unknown. Here, we observe that mice with chronic AMPK activation, resulting from mutation of the AMPK γ2 subunit, exhibit ghrelin signalling-dependent hyperphagia, obesity and impaired pancreatic islet insulin secretion. Humans bearing the homologous mutation manifest a congruent phenotype. Our studies highlight that long-term AMPK activation can have adverse metabolic consequences with implications for pharmacological strategies seeking to chronically activate AMPK systemically to treat metabolic disease.
Project description:Faithful execution of developmental programs relies on the acquisition of unique cell identities from pluripotent progenitors, a process governed by combinatorial inputs from numerous signaling cascades that ultimately dictate lineage-specific transcriptional outputs. Despite growing evidence that metabolism is integrated with many molecular networks, how pathways that control energy homeostasis may affect cell fate decisions is largely unknown. Here, we show that AMPK, a central metabolic regulator, plays critical roles in lineage specification. Although AMPK-deficient embryonic stem cells (ESCs) were normal in the pluripotent state, these cells displayed profound defects upon differentiation, failing to generate chimeric embryos and preferentially adopting an ectodermal fate at the expense of the endoderm during embryoid body (EB) formation. AMPK-/- EBs exhibited reduced levels of Tfeb, a master transcriptional regulator of lysosomes, leading to diminished endolysosomal function. Remarkably, genetic loss of Tfeb also yielded endodermal defects, while AMPK-null ESCs over-expressing this transcription factor normalized their differential potential, revealing an intimate connection between Tfeb/lysosomes and germ layer specification. The compromised endolysosomal system resulting from AMPK or Tfeb inactivation blunted Wnt signaling, while up-regulating this pathway restored expression of endodermal markers. Collectively, these results uncover the AMPK pathway as a novel regulator of cell fate determination during differentiation. 2 WT and 2 AMPK DKO ESC lines were differentiated into embryoid bodies (EBs) for various lengths of time (2, 4, 8, and 12 days) in high and low glucose conditions. Both ESC and EB samples were profiled by mRNA-seq to examine how global gene expression changes associated with ESC differentiation are affected by AMPK deletion.
Project description:SPINT1 is a membrane-anchored serine protease inhibitor that modulates pericellular proteolysis. The pancreas-specific disruption of Spint1 in mice significantly decreased islet size and mass, leading to glucose intolerance, which was causally related to the down-regulation of MafA and insulin. Mechanistically, the silencing of Hepsin (encoding a SPINT1 target protease) counteracted the repressive effect of Spint1 knockdown on MafA and Ins1 expression in β cells. Together, the results suggest that SPINT1 plays a novel role in β cells to maintain glucose homeostasis and insulin production.
Project description:Lee and colleagues demonstrate that sustained activation of AMPK enhances differentiation of iPSC-derived cardiomyocytes. Sustained AMPK activation decreased histone acetylation at known target sites for nuclear-localized sirtuins, suggesting that AMPK activation enhances sirtuin activity. AMPK-induced sirtuin-mediated deacetylation of histone proteins may regulate chromatin accessibility and enhance cardiomyocyte differentiation.
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:Cysteine dioxygenase type 1 (Cdo1) is a key enzyme for cysteine catabolism that is enriched in liver, whose role in NAFLD remains poorly understood. Here, we show that exercise induces the expression of hepatic Cdo1 via the cAMP/PKA/CREB signaling pathway. Hepatocyte-specific knockout of Cdo1 (Cdo1LKO) impairs the effect of exercise against NAFLD, whereas hepatocyte-specific overexpression of Cdo1 (Cdo1LTG) and exercise synergistically ameliorates NAFLD in male mice. Mechanistically, Cdo1 facilitates the binding between AMPK and kinase active Camkk2, which activates AMPK signaling. This promotes fatty acid oxidation and mitochondrial biogenesis in hepatocytes to attenuate hepatosteatosis. Therefore, by promoting hepatic Camkk2-AMPK signaling pathway, Cdo1 acts as an important downstream effector of exercise to combat against NAFLD