MitoNEET preserves muscle insulin sensitivity during iron overload by regulating mitochondrial iron, reactive oxygen species and fission.

Iron overload (IO) is known to contribute to metabolic dysfunctions such as type 2 diabetes and insulin resistance. Using L6 skeletal muscle cells overexpressing the CDGSH iron-sulfur domain-containing protein 1 (CISD1, also known as mitoNEET) (mitoN) protein, we examined the potential role of MitoN in preventing IO-induced insulin resistance. In L6 control cells, IO resulted in insulin resistance which could be prevented by MitoN as demonstrated by western blot of p-Akt and Akt biosensor cells.

The adiponectin-derived peptide ALY688 protects against the development of metabolic dysfunction-associated steatohepatitis.

Metabolic dysfunction-associated steatohepatitis (MASH) is the severe form of non-alcoholic fatty liver disease which has a high potential to progress to cirrhosis and hepatocellular carcinoma, yet adequate effective therapies are lacking. Hypoadiponectinemia is causally involved in the pathogenesis of MASH. This study investigated the pharmacological effects of adiponectin replacement therapy with the adiponectin-derived peptide ALY688 (ALY688-SR) in a mouse model of MASH.

Salubrinal promotes phospho-eIF2α-dependent activation of UPR leading to autophagy-mediated attenuation of iron-induced insulin resistance.

Identification of new mechanisms mediating insulin sensitivity is important to allow validation of corresponding therapeutic targets. In this study, we first used a cellular model of skeletal muscle cell iron overload and found that endoplasmic reticulum (ER) stress and insulin resistance occurred after iron treatment. Insulin sensitivity was assessed using cells engineered to express an Akt biosensor, based on nuclear FoxO localization, as well as western blotting for insulin signaling proteins.

Ischemia-induced cardiac dysfunction is exacerbated in adiponectin-knockout mice due to impaired autophagy flux.

Strategies to enhance autophagy flux have been suggested to improve outcomes in cardiac ischemic models. We explored the role of adiponectin in mediating cardiac autophagy under ischemic conditions induced by permanent coronary artery ligation. We studied the molecular mechanisms underlying adiponectin's cardio-protective effects in adiponectin knockout (Ad-KO) compared with wild-type (WT) mice subjected to ischemia by coronary artery ligation and H9c2 cardiomyocyte cell line exposed to hypoxia.

Cardioprotection by the adiponectin receptor agonist ALY688 in a preclinical mouse model of heart failure with reduced ejection fraction (HFrEF).

Aims: Adiponectin has been shown to mediate cardioprotective effects and levels are typically reduced in patients with cardiometabolic disease. Hence, there has been intense interest in developing adiponectin-based therapeutics. The aim of this translational research study was to examine the functional significance of targeting adiponectin signaling with the adiponectin receptor agonist ALY688 in a mouse model of heart failure with reduced ejection fraction (HFrEF), and the mechanisms of cardiac remodeling leading to cardioprotection.

Autophagy deficiency exacerbates iron overload induced reactive oxygen species production and apoptotic cell death in skeletal muscle cells.

Iron overload is associated with various pathological changes which contribute to metabolic syndrome, many of which have been proposed to occur via damaging tissue through an excessive amount of reactive oxygen species (ROS) production. In this study, we established a model of iron overload in L6 skeletal muscle cells and observed that iron enhanced cytochrome c release from depolarized mitochondria, assayed by immunofluorescent colocalization of cytochrome c with Tom20 and the use of JC-1, respectively. This subsequently elevated apoptosis, determined via use of a caspase-3/7 activatable fluorescent probe and western blotting for cleaved caspase-3.

Role of Mitochondrial Iron Overload in Mediating Cell Death in H9c2 Cells.

Iron overload (IO) is associated with cardiovascular diseases, including heart failure. Our study's aim was to examine the mechanism by which IO triggers cell death in H9c2 cells. IO caused accumulation of intracellular and mitochondrial iron as shown by the use of iron-binding fluorescent reporters, FerroOrange and MitoFerroFluor.

ALY688 elicits adiponectin-mimetic signaling and improves insulin action in skeletal muscle cells.

Adiponectin is well established to mediate many beneficial metabolic effects, and this has stimulated great interest in development and validation of adiponectin receptor agonists as pharmaceutical tools. This study investigated the effects of ALY688, a peptide-based adiponectin receptor agonist, in rat L6 skeletal muscle cells. ALY688 significantly increased phosphorylation of several adiponectin downstream effectors, including AMPK, ACC, and p38MAPK, assessed by immunoblotting and immunofluorescence microscopy.

Inhibitory effects of terrein on lung cancer cell metastasis and angiogenesis.

Cancer metastasis is the leading cause of mortality in cancer patients. Over 70% of lung cancer patients are diagnosed at advanced or metastatic stages, and this results in an increased incidence of mortality. Terrein is a secondary bioactive fungal metabolite isolated from .

Use of 2-dimensional cell monolayers and 3-dimensional microvascular networks on microfluidic devices shows that iron increases transendothelial adiponectin flux via inducing ROS production.

Background: Iron excess is a risk factor for cardiovascular diseases and it is important to understand the effect of iron on vascular permeability, particularly for the transport of large metabolic hormones such as adiponectin.

Methods: We used 2-dimensional monolayers of cultured human dermal microvascular endothelial cells (HDMEC) and human umbilical vein endothelial cells (HUVEC) as well as 3-dimensional microvascular networks to measure transendothelial flux.

Results: Iron supplementation reduced transendothelial electric resistance (TEER).

Author Correction: Iron induces insulin resistance in cardiomyocytes via regulation of oxidative stress.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Iron induces insulin resistance in cardiomyocytes via regulation of oxidative stress.

Iron overload is associated with various pathological changes which contribute to heart failure. Here, we examined mechanisms via which iron alters cardiomyocyte insulin sensitivity. Treatment of primary adult and neonatal cardiomyocytes as well as H9c2 cells with iron decreased insulin sensitivity determined via Western blotting or immunofluorescent detection of Akt and p70S6K phosphorylation and glucose uptake.

Holo-lipocalin-2-derived siderophores increase mitochondrial ROS and impair oxidative phosphorylation in rat cardiomyocytes.

Lipocalin-2 (Lcn2), a critical component of the innate immune response which binds siderophores and limits bacterial iron acquisition, can elicit spillover adverse proinflammatory effects. Here we show that holo-Lcn2 (Lcn2-siderophore-iron, 1:3:1) increases mitochondrial reactive oxygen species (ROS) generation and attenuates mitochondrial oxidative phosphorylation in adult rat primary cardiomyocytes in a manner blocked by -acetyl-cysteine or the mitochondria-specific antioxidant SkQ1. We further demonstrate using siderophores 2,3-DHBA (2,3-dihydroxybenzoic acid) and 2,5-DHBA that increased ROS and reduction in oxidative phosphorylation are direct effects of the siderophore component of holo-Lcn2 and not due to apo-Lcn2 alone.

Lipocalin-2 (NGAL) Attenuates Autophagy to Exacerbate Cardiac Apoptosis Induced by Myocardial Ischemia.

Lipocalin-2 (Lcn2; also termed neutrophil gelatinase-associated lipocalin (NGAL)) levels correlate positively with heart failure (HF) yet mechanisms via which Lcn2 contributes to the pathogenesis of HF remain unclear. In this study, we used coronary artery ligation surgery to induce ischemia in wild-type (wt) mice and this induced a significant increase in myocardial Lcn2. We then compared wt and Lcn2 knockout (KO) mice and observed that wt mice showed greater ischemia-induced caspase-3 activation and DNA damage measured by TUNEL than Lcn2KO mice.

Lipocalin-2 inhibits autophagy and induces insulin resistance in H9c2 cells.

Lipocalin-2 (Lcn2; also known as neutrophil gelatinase associated lipocalin, NGAL) levels are increased in obesity and diabetes and associate with insulin resistance. Correlations exist between Lcn2 levels and various forms or stages of heart failure. Insulin resistance and autophagy both play well-established roles in cardiomyopathy.

Iron metabolism and regulation by neutrophil gelatinase-associated lipocalin in cardiomyopathy.

Neutrophil gelatinase-associated lipocalin (NGAL) has recently become established as an important contributor to the pathophysiology of cardiovascular disease. Accordingly, it is now viewed as an attractive candidate as a biomarker for various disease states, and in particular has recently become regarded as one of the best diagnostic biomarkers available for acute kidney injury. Nevertheless, the precise physiological effects of NGAL on the heart and the significance of their alterations during the development of heart failure are only now beginning to be characterized.