scholarly journals NADPH Oxidase 2 Mediates Myocardial Oxygen Wasting in Obesity

Antioxidants ◽  
2020 ◽  
Vol 9 (2) ◽  
pp. 171 ◽  
Author(s):  
Anne D. Hafstad ◽  
Synne S. Hansen ◽  
Jim Lund ◽  
Celio X. C. Santos ◽  
Neoma T. Boardman ◽  
...  
Keyword(s):  
Nadph Oxidase ◽  
Mitochondrial Function ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Mechanical Efficiency ◽  
Ros Production ◽  
Knock Out ◽  
Obesity And Diabetes ◽  
Mitochondrial Ros ◽  
Nadph Oxidase 2 ◽  
Knock Out Mice

Obesity and diabetes are independent risk factors for cardiovascular diseases, and they are associated with the development of a specific cardiomyopathy with elevated myocardial oxygen consumption (MVO2) and impaired cardiac efficiency. Although the pathophysiology of this cardiomyopathy is multifactorial and complex, reactive oxygen species (ROS) may play an important role. One of the major ROS-generating enzymes in the cardiomyocytes is nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 2 (NOX2), and many potential systemic activators of NOX2 are elevated in obesity and diabetes. We hypothesized that NOX2 activity would influence cardiac energetics and/or the progression of ventricular dysfunction following obesity. Myocardial ROS content and mechanoenergetics were measured in the hearts from diet-induced-obese wild type (DIOWT) and global NOK2 knock-out mice (DIOKO) and in diet-induced obese C57BL/6J mice given normal water (DIO) or water supplemented with the NOX2-inhibitor apocynin (DIOAPO). Mitochondrial function and ROS production were also assessed in DIO and DIOAPO mice. This study demonstrated that ablation and pharmacological inhibition of NOX2 both improved mechanical efficiency and reduced MVO2 for non-mechanical cardiac work. Mitochondrial ROS production was also reduced following NOX2 inhibition, while cardiac mitochondrial function was not markedly altered by apocynin-treatment. Therefore, these results indicate a link between obesity-induced myocardial oxygen wasting, NOX2 activation, and mitochondrial ROS.

scholarly journals Curcumin Ameliorates Heat-Induced Injury through NADPH Oxidase–Dependent Redox Signaling and Mitochondrial Preservation in C2C12 Myoblasts and Mouse Skeletal Muscle

2020 ◽  
Vol 150 (9) ◽  
pp. 2257-2267 ◽  
Author(s):  
Tianzheng Yu ◽  
Jacob Dohl ◽  
Li Wang ◽  
Yifan Chen ◽  
Heath G Gasier ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Nadph Oxidase ◽  
Tissue Injury ◽  
Heat Exposure ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Mitochondrial Morphology ◽  
Ros Production ◽  
C2c12 Myoblasts ◽  
Mitochondrial Ros ◽  
And Function

ABSTRACT Background Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and the mitochondrial electron transport chain are the primary sources of reactive oxygen species (ROS). Previous studies have shown that severe heat exposure damages mitochondria and causes excessive mitochondrial ROS production that contributes to the pathogenesis of heat-related illnesses. Objectives We tested whether the antioxidant curcumin could protect against heat-induced mitochondrial dysfunction and skeletal muscle injury, and characterized the possible mechanism. Methods Mouse C2C12 myoblasts and rat flexor digitorum brevis (FDB) myofibers were treated with 5 μM curcumin; adult male C57BL/6J mice received daily curcumin (15, 50, or 100 mg/kg body weight) by gavage for 10 consecutive days. We compared ROS levels and mitochondrial morphology and function between treatment and nontreatment groups under unheated or heat conditions, and investigated the upstream mechanism and the downstream effect of curcumin-regulated ROS production. Results In C2C12 myoblasts, curcumin prevented heat-induced mitochondrial fragmentation, ROS overproduction, and apoptosis (all P < 0.05). Curcumin treatment for 2 and 4 h at 37°C induced increases in ROS levels by 42% and 59% (dihydroethidium-derived fluorescence), accompanied by increases in NADPH oxidase protein expression by 24% and 32%, respectively (all P < 0.01). In curcumin-treated cells, chemical inhibition and genetic knockdown of NADPH oxidase restored ROS to levels similar to those of controls, indicating NADPH oxidase mediates curcumin-stimulated ROS production. Moreover, curcumin induced ROS-dependent shifting of the mitochondrial fission–fusion balance toward fusion, and increases in mitochondrial mass by 143% and membrane potential by 30% (both P < 0.01). In rat FDB myofibers and mouse gastrocnemius muscles, curcumin preserved mitochondrial morphology and function during heat stress, and prevented heat-induced mitochondrial ROS overproduction and tissue injury (all P < 0.05). Conclusions Curcumin regulates ROS hormesis favoring mitochondrial fusion/elongation, biogenesis, and improved function in rodent skeletal muscle. Curcumin may be an effective therapeutic target for heat-related illness and other mitochondrial diseases.

scholarly journals Mitochondrial Alterations and Enhanced Human Leukocyte/Endothelial Cell Interactions in Type 1 Diabetes

2020 ◽  
Vol 9 (7) ◽  
pp. 2155
Author(s):  
Francesca Iannantuoni ◽  
Aranzazu M. de Marañon ◽  
Zaida Abad-Jiménez ◽  
Francisco Canet ◽  
Pedro Díaz-Pozo ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Type 1 Diabetes ◽  
Adhesion Molecules ◽  
Mitochondrial Function ◽  
Mitochondrial Membrane ◽  
Diabetic Patients ◽  
Ros Production ◽  
Mitochondrial Ros ◽  
Type 1 Diabetic Patients

Type 1 diabetes has been associated with oxidative stress. This study evaluates the rates of oxidative stress, mitochondrial function, leukocyte–endothelium interactions and adhesion molecules in type 1 diabetic patients. The study population consisted of 52 diabetic patients and 46 body-composition and age-matched controls. We assessed anthropometric and metabolic parameters, oxidative stress and mitochondrial function by evaluating reactive oxygen species (ROS) production, mitochondrial ROS production, mitochondrial membrane potential and superoxide dismutase (SOD) and catalase (CAT) expression in polymorphonuclear leukocytes from type 1 diabetic patients. In addition, we evaluated interactions between leukocytes and human umbilical vein endothelial cells (HUVEC), and serum expression of adhesion molecules (P-selectin, VCAM-1 and ICAM-1), proinflammatory cytokines (IL-6 and TNFα) and myeloperoxidase (MPO). HbA1C and glucose levels were higher in diabetic patients than in control subjects, as expected. Mitochondrial function was altered and leukocyte–endothelium interactions were enhanced in diabetic patients, which was evident in the increase in total and mitochondrial ROS production, higher mitochondrial membrane potential, enhanced leukocyte rolling and adhesion, and decreased rolling velocity. Furthermore, we observed an increase in levels of adhesion molecules P-selectin, VCAM-1, and ICAM-1 in these subjects. In addition, type 1 diabetic patients exhibited an increase in proinflammatory mediators TNFα and MPO, and a decreased expression of SOD. The enhancement of leukocyte–endothelium interactions and proinflammatory markers correlated with glucose and HbA1Clevels. Mitochondrial alteration, oxidative stress, and enhanced leukocyte–endothelium interactions are features of type 1 diabetes and may be related to cardiovascular implications.

183 ADDITION OF DIPHENYLENEIODONIUM OR DEHYDROEPIANDROSTERONE TO CULTURE MEDIA INHIBITS REACTIVE OXYGEN SPECIES PRODUCTION DURING THE EARLY CLEAVAGE STAGES OF IN VITRO-PRODUCED PORCINE EMBRYOS

2007 ◽  
Vol 19 (1) ◽  
pp. 208
Author(s):  
N. W. K. Karja ◽  
K. Kikuchi ◽  
M. Ozawa ◽  
M. Fahrudin ◽  
T. Somfai ◽  
...  
Keyword(s):  
Reactive Oxygen Species ◽  
Nadph Oxidase ◽  
Culture Media ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Reactive Oxygen ◽  
Blastocyst Stage ◽  
Control Group ◽  
Ros Production ◽  
Oxygen Species

Nicotinamide adenine dinucleotide phosphate-oxidase (NADPH oxidase), an enzyme required to catalyze the oxidation of NADPH to NADP during the metabolism of glucose via the pentose phosphate pathway (PPP), was considered as contributing to intracellular reactive oxygen species (ROS) production. Production of superoxide anion and H2O2 via NADPH oxidase has been reported on a rabbit blastocyst surface (Manes and Lai 1995 J. Reprod. Fertil. 104, 69–75). The objective of this study was to examine the effects on in vitro development and intracellular ROS content after the addition of diphenyleneiodonium (DPI), an inhibitor of NADPH oxidase, or dehydroepiandrosterone (DHEA), an inhibitor of glucose-6-phosphate dehydrogenase (G6PDH), to culture medium during the early embryonic development of in vitro-produced (IVP) porcine embryos. To confirm that these inhibitors lead to reduction in NADPH concentration in the embryo and hence likely to be inhibiting the PPP, a brilliant cresyl blue (BCB) test was performed on Day 2 (the day of insemination = Day 0) of culture. Porcine cumulus–oocyte complexes were matured and fertilized in vitro as described previously (Kikuchi et al. 2002 Biol. Reprod. 66, 1033–1041). Prezumptive zygotes were then cultured in NCSU-37 supplemented with 5.5 mM glucose and DPI at concentrations of 0.5 or 1 nM or DHEA at concentrations of 10 or 100 �M (DPI-0.5, DPI-1, DHEA-10 and DHEA-100 groups, respectively) from Day 0 to Day 2 of culture. All of the embryos were cultured subsequently until Day 6 in NCSU-37 supplemented with only 5.5 mM glucose. Data were analyzed by ANOVA. On Day 6, the development to the blastocyst stage of embryos in DPI-0.5, DPI-1, DHEA-10, and DHEA-100 groups were 16.1, 17.6, 16.1, and 19.5%, respectively, which were not significantly different from that of the control group (17.5%) (n d 165 per group, 5 replicates). However, the mean cell number in blastocysts derived from DPI-1, DHEA-10, and DHEA-100 groups (40.8 � 2.3, 39.3 � 1.7, and 42.5 � 2.7, respectively) was significantly higher (P < 0.01) than those in the control (33.4 � 1.6) and DPI-0.5 (32.7 � 1.6) groups. At 20 min after an exposure to BCB, the percentage of BCB+ embryos in DPI-1, DHEA-10, and DHEA-100 groups (73.8, 79.9, and 77.8%, respectively) were significantly higher (P < 0.01) than those in the control and DPI-0.5 groups (42% and 53.9%, respectively) (n = 81-92 per group, 6 replicates), indicating that these two inhibitors effectively induce the reduction of NADPH concentration in the embryos. Moreover, the addition of DPI at 1 nM or DHEA at 10 or 100 �M significantly decreased the H2O2 content of Day 2 embryos as compared with control embryos (n = 48-53 per group, 7 replicates). These results suggest that the addition of either DPI or DHEA to the medium during the first 2 days of culture did not impair the development of the embryos to the blastocyst stage. Decrease of cellular ROS production in Day 2 embryos in this study is interpreted as a result of inhibition of the NADPH oxidase by DPI or of the G6PDH by DHEA.

scholarly journals Acetylcholinesterase inhibitor protects against cardiac ischaemia/reperfusion injury via enhancing mitophagy and rebalancing mitochondrial dynamics

2020 ◽  
Vol 41 (Supplement_2) ◽  
Author(s):  
T Khuanjing ◽  
S Palee ◽  
S.C Chattipakorn ◽  
N Chattipakorn
Keyword(s):  
Infarct Size ◽  
Mitochondrial Function ◽  
Sham Group ◽  
Mitochondrial Dynamics ◽  
Vehicle Group ◽  
Lv Function ◽  
Funding Source ◽  
Ros Production ◽  
Ischaemia Reperfusion ◽  
Mitochondrial Ros

Abstract Background Ischaemic heart disease is the most common cause of death globally. Although reperfusion therapy is essential to restore myocardial blood flow, it can also damage heart tissues, this process is known as ischaemia/reperfusion (I/R) injury. Cardiac autonomic imbalance including sympathetic overactivity and diminished parasympathetic activity plays an important role in cardiac I/R injury, resulting in left ventricular (LV) dysfunction. Increased vagus nerve activity by an electrical stimulation from an implantable medical device has been shown to be cardioprotective in cardiac I/R injury. However, the role of pharmacological intervention that increases parasympathetic activity on the heart during I/R is not clear. Purpose We investigated the effects of a parasympathomimetic drug, donepezil, on the heart with I/R injury. We hypothesized that donepezil exerts cardioprotective effects in rats with cardiac I/R injury by attenuating the impairment of cardiac mitochondrial function, mitochondrial dynamics and mitophagy, resulting in improved LV function. Methods Forty male Wistar rats were randomly divided into sham and I/R groups. In I/R group, rats were subjected to acute cardiac I/R injury by ligating left anterior descending coronary artery (LAD) for 30 mins followed by reperfusion for 120 mins, while sham group had similar operation but did not have LAD ligation. Moreover, rats in the I/R group were randomly assigned to be treated with either saline (vehicle group) or donepezil 3 mg/kg by intravenous injection. In donepezil-treated rats, they were divided into 3 subgroups to receive the drug at one of the following time-points; before ischaemia, or during ischaemia, or at the onset of reperfusion. During I/R protocol, LV function was recorded. At the end of protocol, the heart was removed to determine infarct size, cardiac mitochondrial function, mitochondrial dynamics, and mitophagy. Results Rats with cardiac I/R injury showed increased infarct size when compared to sham group (Fig. 1A). Rats in all donepezil-treated groups showed reduction of infarct size compared to the vehicle group. This accounts for ∼63%, ∼47%, and ∼44% reduction for the treatment before ischaemia, during ischaemia and onset of reperfusion, respectively. In addition, all donepezil-treated rats had improved LV function by attenuating the reduction of LV ejection fraction (Fig. 1B). The reduction in cardiac mitochondrial ROS production (Fig. 1C), increased mitophagy as indicated by increased PINK-1 expression (Fig. 1D), and rebalancing mitochondrial dynamics were also found in all donepezil-treated rats. Conclusion Donepezil protects against cardiac I/R injury by reducing mitochondrial ROS production, enhancing mitophagy, and improving mitochondrial dynamics, leading to decreased infarct size and improved cardiac function. Figure 1. The effects of donepezil in cardiac I/R Funding Acknowledgement Type of funding source: Public Institution(s). Main funding source(s): Thailand Research Fund grants TRF-Royal Golden Jubilee Program (TK and NC), RTA6180003 (SCC), RSA6180056 (SP); The NSTDA Research Chair grant from the National Science and Technology Development Agency Thailand (NC)

scholarly journals Dextromethorphan Reduces Oxidative Stress and Inhibits Uremic Artery Calcification

2021 ◽  
Vol 22 (22) ◽  
pp. 12277
Author(s):  
En-Shao Liu ◽  
Nai-Ching Chen ◽  
Tzu-Ming Jao ◽  
Chien-Liang Chen
Keyword(s):  
Oxidative Stress ◽  
Nadph Oxidase ◽  
Vascular Calcification ◽  
Wistar Rats ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Oxidase Inhibitor ◽  
In Vivo Studies ◽  
Ros Production

Medial vascular calcification has emerged as a key factor contributing to cardiovascular mortality in patients with chronic kidney disease (CKD). Vascular smooth muscle cells (VSMCs) with osteogenic transdifferentiation play a role in vascular calcification. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitors reduce reactive oxygen species (ROS) production and calcified-medium–induced calcification of VSMCs. This study investigates the effects of dextromethorphan (DXM), an NADPH oxidase inhibitor, on vascular calcification. We used in vitro and in vivo studies to evaluate the effect of DXM on artery changes in the presence of hyperphosphatemia. The anti-vascular calcification effect of DXM was tested in adenine-fed Wistar rats. High-phosphate medium induced ROS production and calcification of VSMCs. DXM significantly attenuated the increase in ROS production, the decrease in ATP, and mitochondria membrane potential during the calcified-medium–induced VSMC calcification process (p < 0.05). The protective effect of DXM in calcified-medium–induced VSMC calcification was not further increased by NADPH oxidase inhibitors, indicating that NADPH oxidase mediates the effect of DXM. Furthermore, DXM decreased aortic calcification in Wistar rats with CKD. Our results suggest that treatment with DXM can attenuate vascular oxidative stress and ameliorate vascular calcification.

scholarly journals Inhibition of NADPH oxidase 2 (NOX2) prevents sepsis-induced cardiomyopathy by improving calcium handling and mitochondrial function

JCI Insight ◽  
2017 ◽  
Vol 2 (17) ◽  
Author(s):  
Leroy C. Joseph ◽  
Dimitra Kokkinaki ◽  
Mesele-Christina Valenti ◽  
Grace J. Kim ◽  
Emanuele Barca ◽  
...  
Keyword(s):  
Nadph Oxidase ◽  
Mitochondrial Function ◽  
Calcium Handling ◽  
Nadph Oxidase 2

Abstract P346: Endothelial Function and NO Bioavailability are Improved in Angiotensin Ii-treated Transglutaminase-2 Knock-out Mice

Hypertension ◽  
2016 ◽  
Vol 68 (suppl_1) ◽  
Author(s):  
Carmine Savoia ◽  
Emanuele Arrabito ◽  
Sergio Chiandotto ◽  
Carmine Nicoletti ◽  
Raffaella Carletti ◽  
...  
Keyword(s):  
Angiotensin Ii ◽  
Transglutaminase 2 ◽  
Mesenteric Arteries ◽  
Ros Production ◽  
Resistance Arteries ◽  
Response Curves ◽  
Knock Out ◽  
Positive Modulator ◽  
No Bioavailability ◽  
Knock Out Mice

We hypothesized that transglutaminase-2 (TG2) may contribute to the impaired functional properties of resistance arteries from angiotensin-II-treated mice. TG2-knockout mice (TG2-K/O, 12 weeks old, n=6) and wild type (WT) mice were treated or not with angiotensin-II (400ng/kg/min) for 14 days. Blood pressure (BP) and heart rate (HR) were measured by tail-cuff method. Endothelium-dependent and -independent relaxations were assessed by concentration-response curves to acetylcholine (1nM-to-100μM)±L-NAME (100μM) and sodium nitroprusside (10nM-to-1mM) respectively, in mesenteric arteries pre-contracted with norepinephrine (10μM). The expression of p-eNOS-(S1177)/eNOS, NOSIP (the negative modulator of eNOS), NOX-1, and its positive modulator ERp72 were evaluated in aorta by immunoblotting. Reactive oxygen species (ROS) production in aorta was evaluated by dihydroethidium staining. Plasma nitrate/nitrate were measured by ELISA. BP and HR were higher in TG2-K/O mice compared to WT (116.8±0.9 mmHg vs 89.6±1.5 mmHg, P<0.001; and 595.0±15.0 bpm vs 467.1±14.7 bpm, P<0.001, respectively). In both groups, angiotensin-II increased significantly BP (+28% in WT, and +21% in TG2-K/O) and HR (+33% in WT, and +9% in TG2-K/O). Acetylcholine-induced relaxation was preserved in WT and TG2-K/O and it was significantly impaired by angiotensin-II only in WT (-28%). L-NAME blunted this response in all the groups, although this effect was less evident in angiotensin-II-treated WT. Endothelium-independent relaxation was similar in all the groups. Plasma nitrates/nitrates and p-eNOS-(S1177)/eNOS were similar in WT and TG2-K/O, and they were reduced by angiotensin-II significantly only in WT (-37% and -44%, respectively). NOSIP expression was similar in both WT and TG2-K/O and was significantly increased by angiotensin-II only in WT (+40%). ROS production was similar in WT and TG2-K/O and significantly increased by angiotensin-II only in WT (+9%). NOX-1 and ERp72 were similar in WT and TG2-K/O and were significantly increased by angiotensin-II only in WT (+23% and +29%, respectively). In conclusion TG2 may contribute to endothelial dysfunction through the modulation of ROS production and the reduction of NO bioavailability in angiotensin-II infused mice.

scholarly journals p47phox siRNA-Loaded PLGA Nanoparticles Suppress ROS/Oxidative Stress-Induced Chondrocyte Damage in Osteoarthritis

Polymers ◽  
2020 ◽  
Vol 12 (2) ◽  
pp. 443 ◽  
Author(s):  
Hyo Jung Shin ◽  
Hyewon Park ◽  
Nara Shin ◽  
Hyeok Hee Kwon ◽  
Yuhua Yin ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Nadph Oxidase ◽  
Articular Chondrocytes ◽  
Cartilage Damage ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Plga Nanoparticles ◽  
Ros Production ◽  
Therapeutic Value ◽  
Joint Disorder ◽  
Low Levels

Osteoarthritis (OA) is the most common joint disorder that has had an increasing prevalence due to the aging of the population. Recent studies have concluded that OA progression is related to oxidative stress and reactive oxygen species (ROS). ROS are produced at low levels in articular chondrocytes, mainly by the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase, and ROS production and oxidative stress have been found to be elevated in patients with OA. The cartilage of OA-affected rat exhibits a significant induction of p47phox, a cytosolic subunit of the NADPH oxidase, similarly to human osteoarthritis cartilage. Therefore, this study tested whether siRNA p47phox that is introduced with poly (D,L-lactic-co-glycolic acid) (PLGA) nanoparticles (p47phox si_NPs) can alleviate chondrocyte cell death by reducing ROS production. Here, we confirm that p47phox si_NPs significantly attenuated oxidative stress and decreased cartilage damage in mono-iodoacetate (MIA)-induced OA. In conclusion, these data suggest that p47phox si_NPs may be of therapeutic value in the treatment of osteoarthritis.

scholarly journals Mito-TIPTP Increases Mitochondrial Function by Repressing the Rubicon-p22phox Interaction in Colitis-Induced Mice

Antioxidants ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 1954
Author(s):  
Jae-Sung Kim ◽  
Ye-Ram Kim ◽  
Sein Jang ◽  
Sang Geon Wang ◽  
Euni Cho ◽  
...  
Keyword(s):  
Mitochondrial Function ◽  
Metabolic Flux ◽  
Therapeutic Agent ◽  
Nicotinamide Adenine Dinucleotide Phosphate ◽  
Complex Iii ◽  
Mitochondrial Translocation ◽  
Rich Domain ◽  
Mitochondrial Ros ◽  
Lps Activation ◽  
Cysteine Rich Domain

The run/cysteine-rich-domain-containing Beclin1-interacting autophagy protein (Rubicon) is essential for the regulation of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase by interacting with p22phox to trigger the production of reactive oxygen species (ROS) in immune cells. In a previous study, we demonstrated that the interaction of Rubicon with p22phox increases cellular ROS levels. The correlation between Rubicon and mitochondrial ROS (mtROS) is poorly understood. Here, we report that Rubicon interacts with p22phox in the outer mitochondrial membrane in macrophages and patients with human ulcerative colitis. Upon lipopolysaccharide (LPS) activation, the binding of Rubicon to p22phox was elevated, and increased not only cellular ROS levels but also mtROS, with an impairment of mitochondrial complex III and mitochondrial biogenesis in macrophages. Furthermore, increased Rubicon decreases mitochondrial metabolic flux in macrophages. Mito-TIPTP, which is a p22phox inhibitor containing a mitochondrial translocation signal, enhances mitochondrial function by inhibiting the association between Rubicon and p22phox in LPS-primed bone-marrow-derived macrophages (BMDMs) treated with adenosine triphosphate (ATP) or dextran sulfate sodium (DSS). Remarkably, Mito-TIPTP exhibited a therapeutic effect by decreasing mtROS in DSS-induced acute or chronic colitis mouse models. Thus, our findings suggest that Mito-TIPTP is a potential therapeutic agent for colitis by inhibiting the interaction between Rubicon and p22phox to recover mitochondrial function.

scholarly journals Effect of BI-1 on insulin resistance through regulation of CYP2E1

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Geum-Hwa Lee ◽  
Kyoung-Jin Oh ◽  
Hyung-Ryong Kim ◽  
Hye-Sook Han ◽  
Hwa-Young Lee ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Er Stress ◽  
Insulin Signaling ◽  
High Fat Diet ◽  
Stable Expression ◽  
Hepatic Insulin Resistance ◽  
Ros Production ◽  
High Fat ◽  
Knock Out ◽  
Knock Out Mice

Abstract Diet-induced obesity is a major contributing factor to the progression of hepatic insulin resistance. Increased free fatty acids in liver enhances endoplasmic reticulum (ER) stress and production of reactive oxygen species (ROS), both are directly responsible for dysregulation of hepatic insulin signaling. BI-1, a recently studied ER stress regulator, was examined to investigate its association with ER stress and ROS in insulin resistance models. To induce obesity and insulin resistance, BI-1 wild type and BI-1 knock-out mice were fed a high-fat diet for 8 weeks. The BI-1 knock-out mice had hyperglycemia, was associated with impaired glucose and insulin tolerance under high-fat diet conditions. Increased activity of NADPH-dependent CYP reductase-associated cytochrome p450 2E1 (CYP2E1) and exacerbation of ER stress in the livers of BI-1 knock-out mice was also observed. Conversely, stable expression of BI-1 in HepG2 hepatocytes was shown to reduce palmitate-induced ER stress and CYP2E1-dependent ROS production, resulting in the preservation of intact insulin signaling. Stable expression of CYP2E1 led to increased ROS production and dysregulation of insulin signaling in hepatic cells, mimicking palmitate-mediated hepatic insulin resistance. We propose that BI-1 protects against obesity-induced hepatic insulin resistance by regulating CYP2E1 activity and ROS production.

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