AMPK is essential for energy homeostasis regulation and glucose sensing by POMC and AgRP neurons

Hypothalamic AMP-activated protein kinase (AMPK) has been suggested to act as a key sensing mechanism, responding to hormones and nutrients in the regulation of energy homeostasis. However, the precise neuronal populations and cellular mechanisms involved are unclear. The effects of long-term manipulation of hypothalamic AMPK on energy balance are also unknown. To directly address such issues, we generated POMC alpha 2KO and AgRP alpha 2KO mice lacking AMPK alpha 2 in proopiomelanocortin- (POMC-) and agouti-related protein-expressing (AgRP-expressing) neurons, key regulators of energy homeostasis. POMC alpha 2KO mice developed obesity due to reduced energy expenditure and dysregulated food intake but remained sensitive to leptin. in contrast, AgRPa2KO mice developed an age-dependent lean phenotype with increased sensitivity to a melanocortin agonist. Electrophysiological studies in AMPK alpha 2-deficient POMC or AgRP neurons revealed normal leptin or insulin action but absent responses to alterations in extracellular glucose levels, showing that glucose-sensing signaling mechanisms in these neurons are distinct from those pathways utilized by leptin or insulin. Taken together with the divergent phenotypes of POMC alpha 2KO and AgRP alpha 2KO mice, our findings suggest that while AMPK plays a key role in hypothalamic function, it does not act as a general sensor and integrator of energy homeostasis in the mediobasal hypothalamus

Regulation of Glomerular Endothelial Cell Proteoglycans by Glucose

The presence of heparan sulfate proteoglycan (HSPG) in anionic sites in the lamina rara interna of glomerular basement membrane suggests that the proteoglycan may be deposited by the glomerular endothelial cells (GEndo). We have previously demonstrated that bovine GEndo in vitro synthesize perlecan, a species of glomerular basement membrane HSPG. In this study we examined whether high glucose medium regulates the GEndo metabolism of glycopeptides including perlecan. Metabolic labeling of glycoconjugates with 35S-SO4, sequential ion exchange and Sepharose CL-4B chromatography of labeled glycoconjugates, and northern analysis were performed. Incubation of GEndo for 8 to 14 weeks (but not for 1-2 weeks) in medium containing 30 mM glucose resulted in nearly 50% reduction in the synthesis of cell layer and medium 35SO4-labeled low anionic glycoproteins and proteoglycans, including that of basement membrane HSPG (Kav 0.42) compared to GEndo grown in 5 mM glucose medium; no changes in anionic charge density or hydrodynamic size of proteoglycans were noted. Northern analysis demonstrated that the mRNA abundance of perlecan was reduced by 47% in cells incubated with 30 mM glucose. Our data suggest that high glucose medium reduces the GEndo synthesis of perlecan by regulating its gene expression. Reduced synthesis of perlecan by GEndo may contribute to proteinuria seen in diabetic nephropathy

USF-1 Is Critical for Maintaining Genome Integrity in Response to UV-Induced DNA Photolesions

An important function of all organisms is to ensure that their genetic material remains intact and unaltered through generations. This is an extremely challenging task since the cell's DNA is constantly under assault by endogenous and environmental agents. To protect against this, cells have evolved effective mechanisms to recognize DNA damage, signal its presence, and mediate its repair. While these responses are expected to be highly regulated because they are critical to avoid human diseases, very little is known about the regulation of the expression of genes involved in mediating their effects. The Nucleotide Excision Repair (NER) is the major DNA–repair process involved in the recognition and removal of UV-mediated DNA damage. Here we use a combination of in vitro and in vivo assays with an intermittent UV-irradiation protocol to investigate the regulation of key players in the DNA–damage recognition step of NER sub-pathways (TCR and GGR). We show an up-regulation in gene expression of CSA and HR23A, which are involved in TCR and GGR, respectively. Importantly, we show that this occurs through a p53 independent mechanism and that it is coordinated by the stress-responsive transcription factor USF-1. Furthermore, using a mouse model we show that the loss of USF-1 compromises DNA repair, which suggests that USF-1 plays an important role in maintaining genomic stability

Sp1 Expression Is Disrupted in Schizophrenia; A Possible Mechanism for the Abnormal Expression of Mitochondrial Complex I Genes, NDUFV1 and NDUFV2

The prevailing hypothesis regards schizophrenia as a polygenic disease, in which multiple genes combine with each other and with environmental stimuli to produce the variance of its clinical symptoms. We investigated whether the ubiquitous transcription factor Sp1 is abnormally expressed in schizophrenia, and consequently can affect the expression of genes implicated in this disorder. promoter by binding to its three GC-boxes. Both activation and binding were inhibited by mithramycin.These findings suggest that abnormality in Sp1, which can be the main activator/repressor or act in combination with additional transcription factors and is subjected to environmental stimuli, can contribute to the polygenic and clinically heterogeneous nature of schizophrenia

Loss of Sugar Detection by GLUT2 Affects Glucose Homeostasis in Mice

International audienceBACKGROUND: Mammals must sense the amount of sugar available to them and respond appropriately. For many years attention has focused on intracellular glucose sensing derived from glucose metabolism. Here, we studied the detection of extracellular glucose concentrations in vivo by invalidating the transduction pathway downstream from the transporter-detector GLUT2 and measured the physiological impact of this pathway. METHODOLOGY/PRINCIPAL FINDINGS: We produced mice that ubiquitously express the largest cytoplasmic loop of GLUT2, blocking glucose-mediated gene expression in vitro without affecting glucose metabolism. Impairment of GLUT2-mediated sugar detection transiently protected transgenic mice against starvation and streptozotocin-induced diabetes, suggesting that both low- and high-glucose concentrations were not detected. Transgenic mice favored lipid oxidation, and oral glucose was slowly cleared from blood due to low insulin production, despite massive urinary glucose excretion. Kidney adaptation was characterized by a lower rate of glucose reabsorption, whereas pancreatic adaptation was associated with a larger number of small islets. CONCLUSIONS/SIGNIFICANCE: Molecular invalidation of sugar sensing in GLUT2-loop transgenic mice changed multiple aspects of glucose homeostasis, highlighting by a top-down approach, the role of membrane glucose receptors as potential therapeutic targets

The Function of MoGlk1 in Integration of Glucose and Ammonium Utilization in Magnaporthe oryzae

Hexokinases are conserved proteins functioning in glucose sensing and signaling. The rice blast fungus Magnaporthe oryzae contains several hexokinases, including MoHxk1 (hexokinase) and MoGlk1 (glucokinase) encoded respectively by MoHXK1 and MoGLK1 genes. The heterologous expression of MoGlk1 and MoHxk1 in Saccharomyces cerevisiae confirmed their conserved functions. Disruption of MoHXK1 resulted in growth reduction in medium containing fructose as the sole carbon source, whereas disruption of MoGLK1 did not cause the similar defect. However, the ΔMoglk1 mutant displayed decreased proton extrusion and a lower biomass in the presence of ammonium, suggesting a decline in the utilization of ammonium. Additionally, the MoGLK1 allele lacking catalytic activity restored growth to the ΔMoglk1 mutant. Moreover, the expression of MoPMA1 encoding a plasma membrane H+-ATPase decreased in the ΔMoglk1 mutant that can be suppressed by glucose and G-6-P. Thus, MoGlk1, but not MoHxk1, regulates ammonium utilization through a mechanism that is independent from its catalytic activity

The European Hematology Association Roadmap for European Hematology Research. A Consensus Document

Abstract The European Hematology Association (EHA) Roadmap for European Hematology Research highlights major achievements in diagnosis and treatment of blood disorders and identifies the greatest unmet clinical and scientific needs in those areas to enable better funded, more focused European hematology research. Initiated by the EHA, around 300 experts contributed to the consensus document, which will help European policy makers, research funders, research organizations, researchers, and patient groups make better informed decisions on hematology research. It also aims to raise public awareness of the burden of blood disorders on European society, which purely in economic terms is estimated at Euro 23 billion per year, a level of cost that is not matched in current European hematology research funding. In recent decades, hematology research has improved our fundamental understanding of the biology of blood disorders, and has improved diagnostics and treatments, sometimes in revolutionary ways. This progress highlights the potential of focused basic research programs such as this EHA Roadmap. The EHA Roadmap identifies nine sections in hematology: normal hematopoiesis, malignant lymphoid and myeloid diseases, anemias and related diseases, platelet disorders, blood coagulation and hemostatic disorders, transfusion medicine, infections in hematology, and hematopoietic stem cell transplantation. These sections span 60 smaller groups of diseases or disorders. The EHA Roadmap identifies priorities and needs across the field of hematology, including those to develop targeted therapies based on genomic profiling and chemical biology, to eradicate minimal residual malignant disease, and to develop cellular immunotherapies, combination treatments, gene therapies, hematopoietic stem cell treatments, and treatments that are better tolerated by elderly patients. Received December 15, 2015. Accepted January 27, 2016. Copyright © 2016, Ferrata Storti Foundatio

The European Hematology Association Roadmap for European Hematology Research: a consensus document

The European Hematology Association (EHA) Roadmap for European Hematology Research highlights major achievements in diagnosis and treatment of blood disorders and identifies the greatest unmet clinical and scientific needs in those areas to enable better funded, more focused European hematology research. Initiated by the EHA, around 300 experts contributed to the consensus document, which will help European policy makers, research funders, research organizations, researchers, and patient groups make better informed decisions on hematology research. It also aims to raise public awareness of the burden of blood disorders on European society, which purely in economic terms is estimated at €23 billion per year, a level of cost that is not matched in current European hematology research funding. In recent decades, hematology research has improved our fundamental understanding of the biology of blood disorders, and has improved diagnostics and treatments, sometimes in revolutionary ways. This progress highlights the potential of focused basic research programs such as this EHA Roadmap. The EHA Roadmap identifies nine ‘sections’ in hematology: normal hematopoiesis, malignant lymphoid and myeloid diseases, anemias and related diseases, platelet disorders, blood coagulation and hemostatic disorders, transfusion medicine, infections in hematology, and hematopoietic stem cell transplantation. These sections span 60 smaller groups of diseases or disorders. The EHA Roadmap identifies priorities and needs across the field of hematology, including those to develop targeted therapies based on genomic profiling and chemical biology, to eradicate minimal residual malignant disease, and to develop cellular immunotherapies, combination treatments, gene therapies, hematopoietic stem cell treatments, and treatments that are better tolerated by elderly patients