A family of NADPH/NADP biosensors reveals in vivo dynamics of central redox metabolism across eukaryotes.

The NADPH/NADP redox couple is central to metabolism and redox signalling. NADP redox state is differentially regulated by distinct enzymatic machineries at the subcellular compartment level. Nonetheless, a detailed understanding of subcellular NADP redox dynamics is limited by the availability of appropriate tools.

Purinergic receptor P2X7 regulates interleukin-1α mediated inflammation in chronic kidney disease in a reactive oxygen species-dependent manner.

Onset, progression and cardiovascular outcome of chronic kidney disease (CKD) are influenced by the concomitant sterile inflammation. The pro-inflammatory cytokine family interleukin (IL)-1 is crucial in CKD with the key alarmin IL-1α playing an additional role as an adhesion molecule that facilitates immune cell tissue infiltration and consequently inflammation. Here, we investigate calcium ion and reactive oxygen species (ROS)-dependent regulation of different aspects of IL-1α-mediated inflammation.

Tsa1 is the dominant peroxide scavenger and a source of HO-dependent GSSG production in yeast.

Hydrogen peroxide (HO) is an important biological molecule, functioning both as a second messenger in cell signaling and, especially at higher concentrations, as a cause of cell damage. Cells harbor multiple enzymes that have peroxide reducing activity in vitro. However, the contribution of each of these enzymes towards peroxide scavenging in vivo is less clear.

Glucose-stimulated insulin secretion depends on FFA1 and Gq in neonatal mouse islets.

Aims/hypothesis: After birth, the neonatal islets gradually acquire glucose-responsive insulin secretion, a process that is subjected to maternal imprinting. Although NEFA are major components of breastmilk and insulin secretagogues, their role for functional maturation of neonatal beta cells is still unclear. NEFA are the endogenous ligands of fatty acid receptor 1 (FFA1, encoded by Ffar1 in mice), a Gq-coupled receptor with stimulatory effect on insulin secretion.

Co-transplantation of pancreatic islets and microvascular fragments effectively restores normoglycemia in diabetic mice.

Insufficient revascularization of pancreatic islets is one of the major obstacles impairing the success of islet transplantation. To overcome this problem, we introduce in the present study a straightforward strategy to accelerate the engraftment of isolated islets. For this purpose, we co-transplanted 250 islets and 20,000 adipose tissue-derived microvascular fragments (MVF) from donor mice under the kidney capsule as well as 500 or 1000 islets with 40,000 MVF into the subcutaneous space of diabetic mice.

Pro-oxidative priming but maintained cardiac function in a broad spectrum of murine models of chronic kidney disease.

Aims: Patients with chronic kidney disease (CKD) have an increased risk of cardiovascular events and exhibit myocardial changes including left ventricular (LV) hypertrophy and fibrosis, overall referred to as 'uremic cardiomyopathy'. Although different CKD animal models have been studied for cardiac effects, lack of consistent reporting on cardiac function and pathology complicates clear comparison of these models. Therefore, this study aimed at a systematic and comprehensive comparison of cardiac function and cardiac pathophysiological characteristics in eight different CKD models and mouse strains, with a main focus on adenine-induced CKD.

The loss of pancreatic islet NADPH oxidase (NOX)2 improves islet transplantation.

Islet transplantation is a promising treatment strategy for type 1 diabetes mellitus (T1DM) patients. However, oxidative stress-induced graft failure due to an insufficient revascularization is a major problem of this therapeutic approach. NADPH oxidase (NOX)2 is an important producer of reactive oxygen species (ROS) and several studies have already reported that this enzyme plays a crucial role in the endocrine function and viability of β-cells.

Unspecific CTL Killing Is Enhanced by High Glucose TNF-Related Apoptosis-Inducing Ligand.

TNF-related apoptosis inducing ligand (TRAIL) is expressed on cytotoxic T lymphocytes (CTLs) and TRAIL is linked to progression of diabetes. However, the impact of high glucose on TRAIL expression and its related killing function in CTLs still remains largely elusive. Here, we report that TRAIL is substantially up-regulated in CTLs in environments with high glucose (HG) both and .

Lipotoxicity and β-Cell Failure in Type 2 Diabetes: Oxidative Stress Linked to NADPH Oxidase and ER Stress.

A high caloric intake, rich in saturated fats, greatly contributes to the development of obesity, which is the leading risk factor for type 2 diabetes (T2D). A persistent caloric surplus increases plasma levels of fatty acids (FAs), especially saturated ones, which were shown to negatively impact pancreatic β-cell function and survival in a process called lipotoxicity. Lipotoxicity in β-cells activates different stress pathways, culminating in β-cells dysfunction and death.

A systematic review and meta-analysis of murine models of uremic cardiomyopathy.

Chronic kidney disease (CKD) triggers the risk of developing uremic cardiomyopathy as characterized by cardiac hypertrophy, fibrosis and functional impairment. Traditionally, animal studies are used to reveal the underlying pathological mechanism, although variable CKD models, mouse strains and readouts may reveal diverse results. Here, we systematically reviewed 88 studies and performed meta-analyses of 52 to support finding suitable animal models for future experimental studies on pathological kidney-heart crosstalk during uremic cardiomyopathy.

Loss of Mitochondrial Ca Uniporter Limits Inotropic Reserve and Provides Trigger and Substrate for Arrhythmias in Barth Syndrome Cardiomyopathy.

Background: Barth syndrome (BTHS) is caused by mutations of the gene encoding tafazzin, which catalyzes maturation of mitochondrial cardiolipin and often manifests with systolic dysfunction during early infancy. Beyond the first months of life, BTHS cardiomyopathy typically transitions to a phenotype of diastolic dysfunction with preserved ejection fraction, blunted contractile reserve during exercise, and arrhythmic vulnerability. Previous studies traced BTHS cardiomyopathy to mitochondrial formation of reactive oxygen species (ROS).

High Glucose Enhances Cytotoxic T Lymphocyte-Mediated Cytotoxicity.

Cytotoxic T lymphocytes (CTLs) are key players to eliminate tumorigenic or pathogen-infected cells using lytic granules (LG) and Fas ligand (FasL) pathways. Depletion of glucose leads to severely impaired cytotoxic function of CTLs. However, the impact of excessive glucose on CTL functions still remains largely unknown.

Interleukin-1α Is a Central Regulator of Leukocyte-Endothelial Adhesion in Myocardial Infarction and in Chronic Kidney Disease.

Background: Cardiovascular diseases and chronic kidney disease (CKD) are highly prevalent, aggravate each other, and account for substantial mortality. Both conditions are characterized by activation of the innate immune system. The alarmin interleukin-1α (IL-1α) is expressed in a variety of cell types promoting (sterile) systemic inflammation.

Transient NADPH oxidase 2-dependent HO production drives early palmitate-induced lipotoxicity in pancreatic islets.

Modern lifestyles, including lack of physical activity and poor nutritional habits, are driving the rapidly increasing prevalence of obesity and type 2 diabetes. Increased levels of free fatty acids (FFAs), particularly saturated FFAs, in obese individuals have been linked to pancreatic β-cell failure. This process, termed lipotoxicity, involves activation of several stress responses, including ER stress and oxidative stress.

Evidence for NADPH oxidase activation by GPR40 in pancreatic β-cells.

Investigate the involvement of the fatty acids receptor GPR40 in the assembly and activation of NADPH oxidase and the implications on pancreatic β-cell function. BRIN-BD11 β-cells were exposed to GPR40 agonist (GW9508) or linoleic acid in different glucose concentrations. Superoxide and HO were analyzed, respectively, by DHE fluorescence and by fluorescence of the HO sensor, roGFP2-Orp1.

Chronic activation of GPR40 does not negatively impact upon BRIN-BD11 pancreatic β-cell physiology and function.

Background: Free fatty acids (FFAs) are known for their dual effects on insulin secretion and pancreatic β-cell survival. Short-term exposure to FFAs, such as palmitate, increases insulin secretion. On the contrary, long-term exposure to saturated FFAs results in decreased insulin secretion, as well as triggering oxidative stress and endoplasmic reticulum (ER) stress, culminating in cell death.

STIM-Orai Channels and Reactive Oxygen Species in the Tumor Microenvironment.

The tumor microenvironment (TME) is shaped by cancer and noncancerous cells, the extracellular matrix, soluble factors, and blood vessels. Interactions between the cells, matrix, soluble factors, and blood vessels generate this complex heterogeneous microenvironment. The TME may be metabolically beneficial or unbeneficial for tumor growth, it may favor or not favor a productive immune response against tumor cells, or it may even favor conditions suited to hijacking the immune system for benefitting tumor growth.

The mitochondrial oxidoreductase CHCHD4 is present in a semi-oxidized state in vivo.

Disulfide formation in the mitochondrial intermembrane space is an essential process catalyzed by a disulfide relay machinery. In mammalian cells, the key enzyme in this machinery is the oxidoreductase CHCHD4/Mia40. Here, we determined the in vivo CHCHD4 redox state, which is the major determinant of its cellular activity.

Mechanisms and Applications of Redox-Sensitive Green Fluorescent Protein-Based Hydrogen Peroxide Probes.

Significance: Genetically encoded hydrogen peroxide (HO) sensors, based on fusions between thiol peroxidases and redox-sensitive green fluorescent protein 2 (roGFP2), have dramatically broadened the available "toolbox" for monitoring cellular HO changes. Recent Advances: Recently developed peroxiredoxin-based probes such as roGFP2-Tsa2ΔC offer considerably improved HO sensitivity compared with previously available genetically encoded sensors and now permit dynamic, real-time, monitoring of changes in endogenous HO levels.

Critical Issues: The correct understanding and interpretation of probe read-outs is crucial for their meaningful use.

Cardiac effects of SGLT2 inhibitors: the sodium hypothesis.

The effects of intense glycaemic control on macrovascular complications in patients with type 2 diabetes are incompletely resolved, and many glucose-lowering medications negatively affect cardiovascular outcomes. Recently, the EMPA-REG OUTCOME trial revealed that empagliflozin, an inhibitor of the sodium-glucose cotransporter 2 (SGLT2), substantially reduced the risk of hospitalization for heart failure, death from cardiovascular causes, and all-cause mortality in patients with type 2 diabetes mellitus at high cardiovascular risk. Although several mechanisms may explain this benefit, plasma volume contraction and a metabolic switch favouring cardiac ketone bodies oxidation have recently been proposed as the major drivers.

Insulin replacement restores the vesicular secretory apparatus in the diabetic rat lacrimal gland.

Purpose: In the lacrimal gland (LG) acinar cells, signaling regulates the release of secretory vesicles through specific Rab and SNARE exocytotic proteins. In diabetes mellitus (DM), the LGs are dysfunctional. The aim of this work was to determine if secretory apparatus changes were associated with any effects on the secretory vesicles (SV) in diabetic rats as well as the expression levels of constituent Rab and members of the SNARE family, and if insulin supplementation reversed those changes.

Impaired muscarinic type 3 (M3) receptor/PKC and PKA pathways in islets from MSG-obese rats.

Monosodium glutamate-obese rats are glucose intolerant and insulin resistant. Their pancreatic islets secrete more insulin at increasing glucose concentrations, despite the possible imbalance in the autonomic nervous system of these rats. Here, we investigate the involvement of the cholinergic/protein kinase (PK)-C and PKA pathways in MSG β-cell function.

Age-dependent changes in rat lacrimal gland anti-oxidant and vesicular related protein expression profiles.

Purpose: Anti-oxidation and exocytosis are important for maintaining exocrine tissue homeostasis. During aging, functional and structural alterations occur in the lacrimal gland (LG), including oxidative damage to proteins, lipids, and DNA. The aims of the present study were to determine in the aging LG: a) the effects of aging on LG structure and secretory activity and b) changes in the expression of oxidative stress markers.

Mechanisms of control of the free Ca2+ concentration in the endoplasmic reticulum of mouse pancreatic β-cells: interplay with cell metabolism and [Ca2+]c and role of SERCA2b and SERCA3.

Objective: Sarco-endoplasmic reticulum Ca(2+)-ATPase 2b (SERCA2b) and SERCA3 pump Ca(2+) in the endoplasmic reticulum (ER) of pancreatic β-cells. We studied their role in the control of the free ER Ca(2+) concentration ([Ca(2+)](ER)) and the role of SERCA3 in the control of insulin secretion and ER stress.

Research Design And Methods: β-Cell [Ca(2+)](ER) of SERCA3(+/+) and SERCA3(-/-) mice was monitored with an adenovirus encoding the low Ca(2+)-affinity sensor D4 addressed to the ER (D4ER) under the control of the insulin promoter.