Diabetes mellitus abrogates erythropoietin-induced cardioprotection against ischemic-reperfusion injury by alteration of the RISK/GSK-3β signaling

Recent studies reported cardioprotective effects of erythropoietin (EPO) against ischemia–reperfusion (I/R) injury through activation of the reperfusion injury salvage kinase (RISK) pathway. As RISK has been reported to be impaired in diabetes and insulin resistance syndrome, we examined whether EPO-induced cardioprotection was maintained in rat models of type 1 diabetes and insulin resistance syndrome. Isolated hearts were obtained from three rat cohorts: healthy controls, streptozotocin (STZ)-induced diabetes, and high-fat diet (HFD)-induced insulin resistance syndrome. All hearts underwent 25 min ischemia and 30 min or 120 min reperfusion. They were assigned to receive either no intervention or a single dose of EPO at the onset of reperfusion. In hearts from healthy controls, EPO decreased infarct size (14.36 ± 0.60 and 36.22 ± 4.20% of left ventricle in EPO-treated and untreated hearts, respectively, p < 0.05) and increased phosphorylated forms of Akt, ERK1/2, and their downstream target GSK-3β. In hearts from STZ-induced diabetic rats, EPO did not decrease infarct size (32.05 ± 2.38 and 31.88 ± 1.87% in EPO-treated and untreated diabetic rat hearts, respectively, NS) nor did it increase phosphorylation of Akt, ERK1/2, and GSK-3β. In contrast, in hearts from HFD-induced insulin resistance rats, EPO decreased infarct size (18.66 ± 1.99 and 34.62 ± 3.41% in EPO-treated and untreated HFD rat hearts, respectively, p < 0.05) and increased phosphorylation of Akt, ERK1/2, and GSK-3β. Administration of GSK-3β inhibitor SB216763 was cardioprotective in healthy and diabetic hearts. STZ-induced diabetes abolished EPO-induced cardioprotection against I/R injury through a disruption of upstream signaling of GSK-3β. In conclusion, direct inhibition of GSK-3β may provide an alternative strategy to protect diabetic hearts against I/R injury

The Type and the Position of HNF1A Mutation Modulate Age at Diagnosis of Diabetes in Patients with Maturity-Onset Diabetes of the Young (MODY)-3

OBJECTIVE—The clinical expression of maturity-onset diabetes of the young (MODY)-3 is highly variable. This may be due to environmental and/or genetic factors, including molecular characteristics of the hepatocyte nuclear factor 1-α (HNF1A) gene mutation. RESEARCH DESIGN AND METHODS—We analyzed the mutations identified in 356 unrelated MODY3 patients, including 118 novel mutations, and searched for correlations between the genotype and age at diagnosis of diabetes. RESULTS—Missense mutations prevailed in the dimerization and DNA-binding domains (74%), while truncating mutations were predominant in the transactivation domain (62%). The majority (83%) of the mutations were located in exons 1- 6, thus affecting the three HNF1A isoforms. Age at diagnosis of diabetes was lower in patients with truncating mutations than in those with missense mutations (18 vs. 22 years, P = 0.005). Missense mutations affecting the dimerization/DNA-binding domains were associated with a lower age at diagnosis than those affecting the transactivation domain (20 vs. 30 years, P = 10−4). Patients with missense mutations affecting the three isoforms were younger at diagnosis than those with missense mutations involving one or two isoforms (P = 0.03). CONCLUSIONS—These data show that part of the variability of the clinical expression in MODY3 patients may be explained by the type and the location of HNF1A mutations. These findings should be considered in studies for the search of additional modifier genetic factors

Dynamic regulation of mitochondrial network and oxidative functions during 3T3-L1 fat cell differentiation

Mitochondria have been shown to be impaired in insulin resistance-related diseases but have not been extensively studied during the first steps of adipose cell development. This study was designed to determine the sequence of changes of the mitochondrial network and function during the first days of adipogenesis. 3T3-L1 preadipocytes were differentiated into adipocytes without using glitazone compounds. At days 0, 3, 6, 9, and 12, mitochondrial network imaging, mitochondrial oxygen consumption, membrane potential, and oxidative phosphorylation efficiency were assessed in permeabilized cells. Gene and protein expressions related to fatty acid metabolism and mitochondrial network were also determined. Compared to preadipocytes (day 0), new adipocytes (days 6 and 9) displayed profound changes of their mitochondrial network that underwent fragmentation and redistribution around lipid droplets. Drp1 and mitofusin 2 displayed a progressive increase in their gene expression and protein content during the first 9 days of differentiation. In parallel with the mitochondrial network redistribution, mitochondria switched to uncoupled respiration with a tendency towards decreased membrane potential, with no variation of mtTFA and NRF1 gene expression. The expression of PGC1α and NRF2 genes and genes involved in lipid oxidation (UCP2, CD36, and CPT1) was increased. Reactive oxygen species (ROS) production displayed a nadir at day 6 with a concomitant increase in antioxidant enzyme gene expression. This 3T3-L1-based in vitro model of adipogenesis showed that mitochondria adapted to the increased number of lipid droplets by network redistribution and uncoupling respiration. The timing and regulation of lipid oxidation-associated ROS production appeared to play an important role in these changes

The ineluctable requirement for the trans-iron elements molybdenum and/or tungsten in the origin of life

An evolutionary tree of key enzymes from the Complex-Iron-Sulfur-Molybdoenzyme (CISM) superfamily distinguishes “ancient” members, i.e. enzymes present already in the last universal common ancestor (LUCA) of prokaryotes, from more recently evolved subfamilies. The majority of the presented subfamilies and, as a consequence, the Molybdo-enzyme superfamily as a whole, appear to have existed in LUCA. The results are discussed with respect to the nature of bioenergetic substrates available to early life and to problems arising from the low solubility of molybdenum under conditions of the primordial Earth

The GAIA theory: from Lovelock to Margulis. From a homeostatic to a cognitive autopoietic worldview

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The Elusive Third Subunit IIa of the Bacterial B-Type Oxidases: The Enzyme from the Hyperthermophile Aquifex aeolicus

The reduction of molecular oxygen to water is catalyzed by complicated membrane-bound metallo-enzymes containing variable numbers of subunits, called cytochrome c oxidases or quinol oxidases. We previously described the cytochrome c oxidase II from the hyperthermophilic bacterium Aquifex aeolicus as a ba3-type two-subunit (subunits I and II) enzyme and showed that it is included in a supercomplex involved in the sulfide-oxygen respiration pathway. It belongs to the B-family of the heme-copper oxidases, enzymes that are far less studied than the ones from family A. Here, we describe the presence in this enzyme of an additional transmembrane helix “subunit IIa”, which is composed of 41 amino acid residues with a measured molecular mass of 5105 Da. Moreover, we show that subunit II, as expected, is in fact longer than the originally annotated protein (from the genome) and contains a transmembrane domain. Using Aquifex aeolicus genomic sequence analyses, N-terminal sequencing, peptide mass fingerprinting and mass spectrometry analysis on entire subunits, we conclude that the B-type enzyme from this bacterium is a three-subunit complex. It is composed of subunit I (encoded by coxA2) of 59000 Da, subunit II (encoded by coxB2) of 16700 Da and subunit IIa which contain 12, 1 and 1 transmembrane helices respectively. A structural model indicates that the structural organization of the complex strongly resembles that of the ba3 cytochrome c oxidase from the bacterium Thermus thermophilus, the IIa helical subunit being structurally the lacking N-terminal transmembrane helix of subunit II present in the A-type oxidases. Analysis of the genomic context of genes encoding oxidases indicates that this third subunit is present in many of the bacterial oxidases from B-family, enzymes that have been described as two-subunit complexes

The Clinical Variability of Maternally Inherited Diabetes and Deafness Is Associated with the Degree of Heteroplasmy in Blood Leukocytes

Context: Maternally inherited diabetes and deafness (MIDD) is a rare form of diabetes with a matrilineal transmission, sensorineural hearing loss, and macular pattern dystrophy due to an A to G transition at position 3243 of mitochondrial DNA (mtDNA) (m.3243A>G). The phenotypic heterogeneity of MIDD may be the consequence of different levels of mutated mtDNA among mitochondria in a given tissue. Objective: The aim of the present study was thus to ascertain the correlation between the severity of the phenotype in patients with MIDD and the level of heteroplasmy in the blood leukocytes. Participants: The GEDIAM prospective multicenter register was initiated in 1995. Eighty-nine Europid patients from this register, with MIDD and the mtDNA 3243A>G mutation, were included. Patients with MELAS (mitochondrial encephalomyopathy, lactic acidosis, and stroke-like episodes) or with mitochondrial diabetes related to other mutations or to deletions of mtDNA were excluded. Results: A significant negative correlation was found between levels of heteroplasmy and age of the patients at the time of sampling for molecular analysis, age at the diagnosis of diabetes, and body mass index. After adjustment for age at sampling for molecular study and gender, the correlation between heteroplasmy levels and age at the diagnosis of diabetes was no more significant. The two other correlations remained significant. A significant positive correlation between levels of heteroplasmy and HbA1c was also found and remained significant after adjustment for age at molecular sampling and gender. Conclusions: These results support the hypothesis that heteroplasmy levels are at least one of the determinants of the severity of the phenotype in MIDD. Heteroplasmy levels are at least one of the determinants of the severity of the phenotype of maternally inherited diabetes and deafness

The ocean sampling day consortium

Ocean Sampling Day was initiated by the EU-funded Micro B3 (Marine Microbial Biodiversity, Bioinformatics, Biotechnology) project to obtain a snapshot of the marine microbial biodiversity and function of the world’s oceans. It is a simultaneous global mega-sequencing campaign aiming to generate the largest standardized microbial data set in a single day. This will be achievable only through the coordinated efforts of an Ocean Sampling Day Consortium, supportive partnerships and networks between sites. This commentary outlines the establishment, function and aims of the Consortium and describes our vision for a sustainable study of marine microbial communities and their embedded functional traits

Function-Based Discovery of Significant Transcriptional Temporal Patterns in Insulin Stimulated Muscle Cells

Background: Insulin action on protein synthesis (translation of transcripts) and post-translational modifications, especially of those involving the reversible modifications such as phosphorylation of various signaling proteins, are extensively studied but insulin effect on transcription of genes, especially of transcriptional temporal patterns remains to be fully defined. Methodology/Principal Findings: To identify significant transcriptional temporal patterns we utilized primary differentiated rat skeletal muscle myotubes which were treated with insulin and samples were collected every 20 min for 8 hours. Pooled samples at every hour were analyzed by gene array approach to measure transcript levels. The patterns of transcript levels were analyzed based on a novel method that integrates selection, clustering, and functional annotation to find the main temporal patterns associated to functional groups of differentially expressed genes. 326 genes were found to be differentially expressed in response to in vitro insulin administration in skeletal muscle myotubes. Approximately 20 % of the genes that were differentially expressed were identified as belonging to the insulin signaling pathway. Characteristic transcriptional temporal patterns include: (a) a slow and gradual decrease in gene expression, (b) a gradual increase in gene expression reaching a peak at about 5 hours and then reaching a plateau or an initial decrease and other different variable pattern of increase in gene expression over time. Conclusion/Significance: The new method allows identifying characteristic dynamic responses to insulin stimulus, commo