Selective Inactivation of c-Jun NH2-Terminal Kinase in Adipose Tissue Protects Against Diet-Induced Obesity and Improves Insulin Sensitivity in Both Liver and Skeletal Muscle in Mice

OBJECTIVE Obesity is associated with increased activation of the c-Jun NH2-terminal kinase (JNK) in several metabolic organs, including adipose tissue, liver, and skeletal muscle. In this study, we aimed to define the role of JNK activation in adipose tissue in the development of obesity-related insulin resistance. RESEARCH DESIGN AND METHODS Transgenic mice with adipose tissue–specific overexpression of dominant-negative JNK (ap2-dn-JNK) under the transcriptional control of the aP2 gene promoter were generated and subjected to metabolic characterization together with the wild-type littermates. RESULTS On a high-fat diet (HFD), the ap2-dn-JNK mice displayed a marked suppression of both JNK1 and JNK2 activation in their adipose tissue, accompanied by a marked reduction in weight gain, fat mass, and size of the adipocytes. The transgenic mice were resistant to the deleterious impact of an HFD on systemic insulin sensitivity, glucose tolerance, and hepatic steatosis. Reduced hepatic gluconeogenesis was evident in in vivo and ex vivo studies and showed greater insulin-induced glucose uptake in skeletal muscles. These changes were accompanied by reduced macrophage infiltration in adipose tissue, decreased production of proinflammatory adipokines, and increased expression of adiponectin. Indirect calorimetry analysis showed that the transgenic mice had significant increases in oxygen consumption and reductions in respiration exchange rates compared with their wild-type littermates. CONCLUSIONS Selective suppression of JNK activation in adipose tissue alone is sufficient to counteract HFD-induced obesity and its associated metabolic dysregulations, in part through an increase in energy expenditure and a decrease in systemic inflammation

Strain-dependent host transcriptional responses to toxoplasma infection are largely conserved in mammalian and avian hosts

Toxoplasma gondii has a remarkable ability to infect an enormous variety of mammalian and avian species. Given this, it is surprising that three strains (Types I/II/III) account for the majority of isolates from Europe/North America. The selective pressures that have driven the emergence of these particular strains, however, remain enigmatic. We hypothesized that strain selection might be partially driven by adaptation of strains for mammalian versus avian hosts. To test this, we examine in vitro, strain-dependent host responses in fibroblasts of a representative avian host, the chicken (Gallus gallus). Using gene expression profiling of infected chicken embryonic fibroblasts and pathway analysis to assess host response, we show here that chicken cells respond with distinct transcriptional profiles upon infection with Type II versus III strains that are reminiscent of profiles observed in mammalian cells. To identify the parasite drivers of these differences, chicken fibroblasts were infected with individual F1 progeny of a Type II x III cross and host gene expression was assessed for each by microarray. QTL mapping of transcriptional differences suggested, and deletion strains confirmed, that, as in mammalian cells, the polymorphic rhoptry kinase ROP16 is the major driver of strain-specific responses. We originally hypothesized that comparing avian versus mammalian host response might reveal an inversion in parasite strain-dependent phenotypes; specifically, for polymorphic effectors like ROP16, we hypothesized that the allele with most activity in mammalian cells might be less active in avian cells. Instead, we found that activity of ROP16 alleles appears to be conserved across host species; moreover, additional parasite loci that were previously mapped for strain-specific effects on mammalian response showed similar strain-specific effects in chicken cells. These results indicate that if different hosts select for different parasite genotypes, the selection operates downstream of the signaling occurring during the beginning of the host's immune response. © 2011 Ong et al

Protection of pancreatic INS-1 β-cells from glucose- and fructose-induced cell death by inhibiting mitochondrial permeability transition with cyclosporin A or metformin

Hyperglycemia is detrimental to β-cell viability, playing a major role in the progression of β-cell loss in diabetes mellitus. The permeability transition pore (PTP) is a mitochondrial channel involved in cell death. Recent evidence suggests that PTP inhibitors prevent hyperglycemia-induced cell death in human endothelial cells. In this work, we have examined the involvement of PTP opening in INS-1 cell death induced by high levels of glucose or fructose. PTP regulation was studied by measuring the calcium retention capacity in permeabilized INS-1 cells and by confocal microscopy in intact INS-1 cells. Cell death was analyzed by flow cytometry. We first reported that metformin and cyclosporin A (CsA) prevented Ca2+-induced PTP opening in permeabilized and intact INS-1 cells. We then showed that incubation of INS-1 cells in the presence of 30 mM glucose or 2.5 mM fructose induced PTP opening and led to cell death. As both metformin and CsA prevented glucose- and fructose- induced PTP opening, and hampered glucose- and fructose- induced cell death, we conclude that PTP opening is involved in high glucose- and high fructose- induced INS-1 cell death. We therefore suggest that preventing PTP opening might be a new approach to preserve β-cell viability

Freqüência e intensidade parasitária de helmintos gastrintestinais em cães sem dono em Araçatuba-SP

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Conductive cotton prepared by polyaniline in situ polymerization using laccase

The high-redox-potential catalyst laccase, isolated from Aspergillus, was first used as a biocatalyst in the oxidative polymerization of water-soluble conductive polyaniline, and then conductive cotton was prepared by in situ polymerization under the same conditions. The polymerization of aniline was performed in a water dispersion of sodium dodecylbenzenesulfonate (SDBS) micellar solution with atmospheric oxygen serving as the oxidizing agent. This method is ecologically clean and permits a greater degree of control over the kinetics of the reaction. The conditions for polyaniline synthesis were optimized. Characterizations of the conducting polyaniline and cotton were carried out using Fourier transform infrared spectroscopy, UV–vis spectroscopy, cyclic voltammetry, the fabric induction electrostatic tester, and the far-field EMC shielding effectiveness test fixture.This work was financially supported by the National Natural Science Foundation of China (21274055, 51173071), the Program for New Century Excellent Talents in University (NCET-12-0883), the Natural Science Foundation of Jiangsu Province (BK2011157), the Fundamental Research Funds for the Central Universities (JUSRP51312B), and the Program for Changjiang Scholars and Innovative Research Team in University (IRT1135)

TAT-Mediated Transduction of MafA Protein In Utero Results in Enhanced Pancreatic Insulin Expression and Changes in Islet Morphology

Alongside Pdx1 and Beta2/NeuroD, the transcription factor MafA has been shown to be instrumental in the maintenance of the beta cell phenotype. Indeed, a combination of MafA, Pdx1 and Ngn3 (an upstream regulator of Beta2/NeuroD) was recently reported to lead to the effective reprogramming of acinar cells into insulin-producing beta cells. These experiments set the stage for the development of new strategies to address the impairment of glycemic control in diabetic patients. However, the clinical applicability of reprogramming in this context is deemed to be poor due to the need to use viral vehicles for the delivery of the above factors. Here we describe a recombinant transducible version of the MafA protein (TAT-MafA) that penetrates across cell membranes with an efficiency of 100% and binds to the insulin promoter in vitro. When injected in utero into living mouse embryos, TAT-MafA significantly up-regulates target genes and induces enhanced insulin production as well as cytoarchitectural changes consistent with faster islet maturation. As the latest addition to our armamentarium of transducible proteins (which already includes Pdx1 and Ngn3), the purification and characterization of a functional TAT-MafA protein opens the door to prospective therapeutic uses that circumvent the use of viral delivery. To our knowledge, this is also the first report on the use of protein transduction in utero

Arachidonic acid actions on functional integrity and attenuation of the negative effects of palmitic acid in a clonal pancreatic β-cell line

Chronic exposure of pancreatic β-cells to saturated non-esterified fatty acids can lead to inhibition of insulin secretion and apoptosis. Several previous studies have demonstrated that saturated fatty acids such as PA (palmitic acid) are detrimental to β-cell function compared with unsaturated fatty acids. In the present study, we describe the effect of the polyunsaturated AA (arachidonic acid) on the function of the clonal pancreatic β-cell line BRIN-BD11 and demonstrate AA-dependent attenuation of PA effects. When added to β-cell incubations at 100 μM, AA can stimulate cell proliferation and chronic (24 h) basal insulin secretion. Microarray analysis and/or real-time PCR indicated significant AA-dependent up-regulation of genes involved in proliferation and fatty acid metabolism [e.g. Angptl (angiopoietin-like protein 4), Ech1 (peroxisomal Δ3,5,Δ2,4-dienoyl-CoA isomerase), Cox-1 (cyclo-oxygenase-1) and Cox-2, P<0.05]. Experiments using specific COX and LOX (lipoxygenase) inhibitors demonstrated the importance of COX-1 activity for acute (20 min) stimulation of insulin secretion, suggesting that AA metabolites may be responsible for the insulinotropic effects. Moreover, concomitant incubation of AA with PA dose-dependently attenuated the detrimental effects of the saturated fatty acid, so reducing apoptosis and decreasing parameters of oxidative stress [ROS (reactive oxygen species) and NO levels] while improving the GSH/GSSG ratio. AA decreased the protein expression of iNOS (inducible NO synthase), the p65 subunit of NF-κB (nuclear factor κB) and the p47 subunit of NADPH oxidase in PA-treated cells. These findings indicate that AA has an important regulatory and protective β-cell action, which may be beneficial to function and survival in the ‘lipotoxic’ environment commonly associated with Type 2 diabetes mellitus

Ectopic PDX-1 Expression Directly Reprograms Human Keratinocytes along Pancreatic Insulin-Producing Cells Fate

BACKGROUND: Cellular differentiation and lineage commitment have previously been considered irreversible processes. However, recent studies have indicated that differentiated adult cells can be reprogrammed to pluripotency and, in some cases, directly into alternate committed lineages. However, although pluripotent cells can be induced in numerous somatic cell sources, it was thought that inducing alternate committed lineages is primarily only possible in cells of developmentally related tissues. Here, we challenge this view and analyze whether direct adult cell reprogramming to alternate committed lineages can cross the boundaries of distinct developmental germ layers. METHODOLOGY/PRINCIPAL FINDINGS: We ectopically expressed non-integrating pancreatic differentiation factors in ectoderm-derived human keratinocytes to determine whether these factors could directly induce endoderm-derived pancreatic lineage and β-cell-like function. We found that PDX-1 and to a lesser extent other pancreatic transcription factors, could rapidly and specifically activate pancreatic lineage and β-cell-like functional characteristics in ectoderm-derived human keratinocytes. Human keratinocytes transdifferentiated along the β cell lineage produced processed and secreted insulin in response to elevated glucose concentrations. Using irreversible lineage tracing for KRT-5 promoter activity, we present supporting evidence that insulin-positive cells induced by ectopic PDX-1 expression are generated in ectoderm derived keratinocytes. CONCLUSIONS/SIGNIFICANCE: These findings constitute the first demonstration of human ectoderm cells to endoderm derived pancreatic cells transdifferentiation. The study represents a proof of concept which suggests that transcription factors induced reprogramming is wider and more general developmental process than initially considered. These results expanded the arsenal of adult cells that can be used as a cell source for generating functional endocrine pancreatic cells. Directly reprogramming somatic cells into alternate desired tissues has important implications in developing patient-specific, regenerative medicine approaches

Postnatal Expansion of the Pancreatic β-Cell Mass Is Dependent on Survivin

OBJECTIVE—Diabetes results from a deficiency of functional β-cells due to both an increase in β-cell death and an inhibition of β-cell replication. The molecular mechanisms responsible for these effects in susceptible individuals are mostly unknown. The objective of this study was to determine whether a gene critical for cell division and cell survival in cancer cells, survivin, might also be important for β-cells