Modulation of glucose-related metabolic pathways controls glucose level in airway surface liquid and fight oxidative stress in cystic fibrosis cells.

Direct and indirect evidences show that elevated glucose concentrations in airway surface liquid (ASL) promote lung infection by pathogens, playing a role in the progression of the Cystic Fibrosis (CF) disease. The joint action of transporter/s for glucose and of the cellular enzymes is essential in order to try to lower ASL glucose level. Inside the cell, the glycolysis and the pentose phosphate pathway (PPP) compete for the utilization of glucose-6-phosphate (G6P), the product in which glucose, after entry within the cell and phosphorylation, is trapped. The study aims to clarify whether, modulating the activity of enzymatic proteins and/or the level of metabolites/cofactors, involved in intracellular glucose utilization, a lowering of the extracellular glucose level in CF occurs. Biochemical approaches have enabled us to understand i) how G6P is shunted between glycolysis and PPP and ii) that mitochondria, more than enzymes/cofactors participating to the two cell glucose utilization pathways, are protagonists of the scene in counteracting the high ASL glucose level as well as oxidative stress in CF.

Aberrant GSH reductase and NOX activities concur with defective CFTR to pro-oxidative imbalance in cystic fibrosis airways.

Cystic fibrosis (CF) is associated to impaired Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) channel also causing decreased glutathione (GSH) secretion, defective airway bacterial clearance and inflammation. Here we checked the main ROS-producing and ROS-scavenging enzymes as potential additional factors involved in CF pathogenesis. We found that CFBE41o-cells, expressing F508del CFTR, have increased NADPH oxidase (NOX) activity and expression level, mainly responsible of the increased ROS production, and decreased glutathione reductase (GR) activity, not dependent on GR protein level decrease. Furthermore, defective CFTR proved to cause both extracellular and intracellular GSH level decrease, probably by reducing the amount of extracellular GSH-derived cysteine required for cytosolic GSH synthesis. Importantly, we provide evidence that defective CFTR and NOX/GR activity imbalance both contribute to NADPH and GSH level decrease and ROS overproduction in CF cells.

Functional characterization of the oxidative capacity of mitochondria and glycolytic assessment in benthic aquatic organisms.

The metabolism of benthic aquatic invertebrates, populating transitional water ecosystems, is influenced by both physiological and environmental factors, thus involving an adjustment of physiological processes which has a metabolic cost. In order to discover changes in metabolic pathways in response to specific factors, it's firstly necessary characterizing the principal cellular metabolic activities of the small benthic aquatic organisms. We approach here the bioenergetic state issue of two benthic organisms, i.e. Lekanesphaera monodi and Gammarus insensibilis, evidencing that no apparent and statistically significative differences between them in aerobic as well in glycolytic capacities are detected, except for COX activity.

Mitochondrial respiratory chain Complexes I and IV are impaired by ß-amyloid via direct interaction and through Complex I-dependent ROS production, respectively.

Here we investigate the effect of ß-amyloid on mitochondrial respiratory function, i.e. mitochondrial oxygen consumption and membrane potential generation as well as the individual activities of both the mitochondrial Complexes I-IV, that compose mitochondrial electron transport chain, and the ATP synthase, by using homogenate from cerebellar granule cells, treated with low concentrations of ß-amyloid, and Alzheimer synaptic-enriched brain samples. We found that ß-amyloid caused both a selective defect in Complex I activity associated with an increase (5 fold) of intracellular reactive oxygen species and an impairment of Complex IV likely due to membrane lipid peroxidation. In addition, a 130% increase of the GSSG/GSH ratio was measured in Alzheimer brains with respect to age-matched controls. Knowing the mechanisms of action of ß-amyloid could allow to mitigate or even to interrupt the toxic cascade that leads a cell to death. The results of this study represent an important innovation because they offer the possibility to act at mitochondrial level and on specific sites to protect cells, for example by preventing the interaction of ß-amyloid with the identified targets, by stabilizing or by restoring mitochondrial function or by interfering with the energy metabolism.