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Recombinant adeno-associated viruses (rAAVs) are useful vectors for expressing genes of interest in vivo because of their low immunogenicity and long-term gene expression. Various mutations have been introduced in recent years and have enabled high-efficacy, stabilized, and organ-oriented transduction. Our purpose for using rAAV is to express our target gene in the mouse lung to investigate pulmonary artery hypertension. We constructed a self-complementary AAV having mutant capsids with the ESGHGYF insert, which directs the vectors to lung endothelial cells. However, when this mutant virus was purified from the producing cells by the conventional method using an ultracentrifuge, it resulted in a low yield. In addition, the purification method using an ultracentrifuge is tedious and labor-intensive. Therefore, we aimed to develop a simple, high-quality method for obtaining enough lung-targeted rAAV. First, we modified amino acids (T491V and Y730F) of the capsid to stabilize the rAAV from degradation, and we optimized culture conditions. Next, we noticed that many rAAVs were released from the cells into the culture medium. We, therefore, improved our purification method by purifying from the culture medium without the ultracentrifugation step. Purification without ultracentrifugation had the problem that impurities were mixed in, causing inflammation. However, by performing PEG precipitation and chloroform extraction twice, we were able to purify rAAV that caused only as little inflammation as that obtained by the ultracentrifuge method. Sufficient rAAV was obtained and can now be administered to a rat as well as mice from a single dish: 1.50 × 10

One of the biochemical abnormalities found in diabetic tissues is a decrease in the cytosolic oxidized to reduced forms of the nicotinamide adenine dinucleotide ratio (NAD+/NADH also known as pseudohypoxia) caused by oxidation of excessive substrates (glucose through the polyol pathway, free fatty acids and lactate). Subsequently, a decline in NAD+ levels as a result of the activation of poly adenine nucleotide diphosphate‐ribose polymerase (mainly in type 1 diabetes) or the inhibition of adenine nucleotide monophosphate‐activated protein kinase (in type 2 diabetes). Thus, replenishment of NAD+ levels by nicotinamide‐related compounds could be beneficial. However, these compounds also increase nicotinamide catabolites that cause oxidative stress. This is particularly troublesome for patients with diabetes, because they have impaired nicotinamide salvage pathway reactions at the level of nicotinamide phosphoribosyl transferase and phosphoribosyl pyrophosphate, which occurs by the following mechanisms. First, phosphoribosyl pyrophosphate synthesis from pentose phosphate pathway is compromised by a decrease in plasma thiamine and transketolase activity. Second, nicotinamide phosphoribosyl transferase expression is decreased because of reduced adenosine monophosphate‐activated protein kinase activity, which occurs in type 2 diabetes. The adenosine monophosphate‐activated protein kinase inhibition is caused by an activation of protein kinase C and D1 as a result of enhanced diacylglycerol synthesis caused by pseudohypoxia and increased fatty acids levels. In this regard, nicotinamide‐related compounds should be given with caution to treat diabetes. To minimize the risk and maximize the benefit, nicotinamide‐related compounds should be taken with insulin sensitizers (for type 2 diabetes), polyphenols, benfotiamine, acetyl‐L‐carnitine and aldose reductase inhibitors. The efficacy of these regimens can be monitored by measuring serum NAD+ and urinary nicotinamide catabolites.

The long-term prognostic value of the derivatives of reactive oxidative metabolites (d-ROMs) oxidative stress test, which measures hydroperoxide in blood, has not been fully investigated.We administered the d-ROMs test to 265 patients with cardiovascular disease (204 men, 61 women; age, 65 ± 13 years) and followed these patients for up to 10 years. During the observational period of 5.82 (2.47-8.34) years, 31 (12%) patients died, including 20 (8%) of cardiovascular death, and 33 (12%) had major adverse cardiovascular events (MACEs). Cox regression analysis revealed that patients with a d-ROMs value ≥395 U.CARR had a greater risk for all-cause mortality [unadjusted hazard ratio (95% confidence interval), 3.586 (1.772-7.257)], cardiovascular death [7.034 (2.805-17.640)], and MACEs [4.440 (2.237-8.814)] (p 0.001 for all). In a model adjusted for age, sex, estimated glomerular filtration rate, C-reactive protein, diabetes, hypertension, hyperlipidemia, coronary artery diseases, current smoking, and log-transformed brain natriuretic peptide, all-cause death [2.311 (1.059-5.135), p = 0.036], cardiovascular death [4.398 (1.599-12.099), p = 0.004], MACEs [2.696 (1.266-5.739), p = 0.010] were still significant in patients with high d-ROMS values.A high d-ROMs value is an independent predictor of the long-term risk of cardiovascular mortality. A d-ROMs value of 395 U.CARR was considered to be an appropriate threshold for distinguishing prognosis.

Introduction: Pulmonary arterial hypertension (PAH) is a progressive disease, characterized by abnormal muscularization and endothelial dysfunction in pulmonary artery (PA). Previous study showed that endothelial extracellular signal-regulated kinase 2 (eERK2) released vasoconstrictive factors and decreased NO bioactivity resulting in obese-induced hypertension and endothelial dysfunction. However, the role of eERK2 in the pathogenesis of PAH remains to be elucidated. Hypothesis: We hypothesized eERK2 impaired eNOS function and progressed the pathogenesis of PAH. Methods and Results: We generated eERK2 knock out mice (EE2KO) crossing Tie2-Cre mice and ERK2 flox mice and induced PAH by exposing mice to chronic hypoxia (10%) for 4 weeks. The littermate ERK2 flox mice without Cre expression were used as Control (Ctr). Immuno-histochemical staining showed the deficiency of eERK2 expression in the PA of EE2KO. We assessed the medial thickness of pulmonary arteries (MTPA) and measured right ventricular systolic pressure (RVSP). Although Ctr exhibited the progression of PA muscularization with an increase in MTPA, EE2KO revealed the significantly attenuated MTPA under hypoxic condition. Moreover, we found the lower RVSPs in EE2KO than those in Ctr under hypoxia in spite of similar RVSPs in normoxia. In RT-PCR, lung endothelin1 (ET1) gene expression was significantly lower in EE2KO than Ctr under hypoxia. Interestingly, hypoxia increased eNOS protein expression both in Ctr and EE2KO with Western blot analysis. The phosphorylation of AMPKα and eNOS were up-regulated in the lungs of EE2KO relative to Ctr under hypoxia. In addition, eNOS dimer/monomer ratios with non redusing SDS-PAGE was significantly increased in EE2KO compared to the Ctr under hypoxia (1.29±0.10 vs. 0.87±0.02, P=0.02, dimer / monomer ratios), suggesting improved eNOS uncoupling. Conclusions: These findings suggest that hypoxia increased eNOS expression and function, and that eERK2 impaired eNOS function by decreasing the phosphorylation of AMPKα and eNOS, and inducing eNOS uncoupling. In addition, ET1 synthesis through eERK2 might contribute to these pathogenesis of PAH with hypoxia.

Introduction: Right ventricular (RV) dysfunction is the strongest predictor of mortality in pulmonary artery hypertension (PAH). Reactive oxygen species in heart failure cause irreversible oxidation of sarcoplasmic reticulum (SR) Ca 2+ -ATPase2 (SERCA2) C674, which results in SERCA2 dysfunction and intracellular Ca 2+ overload. However, the contribution of the loss of the thiol on C674 SERCA2 and RV failure in PAH remains unclear. Hypothesis: The loss of the thiol on C674 SERCA2 contributes to the RV dysfunction in PAH. Methods & Results: We employed the SERCA2 C674S heterozygote knock-in (SKI) mice, in which C674 is replaced by serine, mimics oxidative modification of SERCA2 by loss of the specific thiol. Wild-type mice (WT) and SKI were exposed to either normoxia (Nx) or chronic hypoxia (Hx) for four weeks. Hypoxia elevated RV systolic pressure (WT-Nx: 21.4mmHg vs. WT-Hx: 37.0mmHg, P2+ transient measurement of isolated myocytes with Fluo-4, SKI prolonged the time to 50% of cytosolic Ca 2+ extrusion (T50) and lower the peak Ca 2+ transient amplitude (F/F0) than WT under Nx. Prolonged T50 and lowered peak F/F0 were observed in WT-Hx, both of which additionally progressed in SKI-Hx. Conclusions: Hypoxia impaired SR Ca 2+ homeostasis in RV. SKI additionally impaired SR Ca 2+ homeostasis with the progression of RV hypertrophy. The loss of the thiol on C674 SERCA2 contributed to the pathogenesis of RV failure in PAH.

Background: Extracellular signal-regulated kinases 1/2 (ERK1/2) play significant roles in proliferation, migration, and cell death. Tyrosine kinase inhibitors (TKIs) have a serious concern for cardiotoxicity and these agents target to EGFR/Ras/Raf/MEK/ERK pathway. In previous reports, SM22α-Cre drived EGFR receptor knockout mice revealed cardiac dysfunction. Hypothesis: We hypothesized if SM22α-Cre drived ERK2 contributed to the cardiac dysfunction mimicking toxicity of TKIs. Methods & Results: We generated SM22α-drived ERK2 knockout mice (SM22α-EKO) by crossing SM22α-Cre mice and ERK2-flox mice. The protein expressions of ERK2 in aorta and heart were markedly lowered in SM22α-EKO, whereas similar in brain, kidney, liver, spleen, and bone marrow. SM22α-EKO displayed lower exercise tolerance and peak oxygen consumptions. Echocardiography revealed left ventricular thickness and dilatation with decreased % fraction shortening (21±4 vs. 38±2%, p=0.0002). Pathological study showed that heart weight was twice accompanied by increases in cardiomyocyte volume, stronger cardiac fibrosis, and inflammations (Figure 1). Western blot analysis showed that the phosphorylation of Akt, p-38 MAP kinase, and STAT3 were also up-regulated in SM22α-EKO with control. Phenylephrine - induced vascular contraction was increased and acetylcholine - induced relaxation was impaired in SM22α-EKO. Finally, SM22α-EKO significantly reduced life span in the Kaplan-Meier plot (Figure 2). Conclusion: SM22α-EKO mice revealed spontaneous cardiac dysfunction with the activation of multiple signaling cascades for hypertrophy and inflammation resulting in sudden death. Deletion of ERK2 in heart and smooth muscle cells also led to hypercontraction of phenylephrine / endothelial dysfunction and perivascular cardiac fibrosis and inflammation. SM22α-EKO might be a valuable model for TKI - induced cardiotoxicity.

Background There is a gradual progression from paroxysmal to persistent atrial fibrillation (AF) in humans. To elucidate the mechanism involved, the creation of an artificial atrial substrate to persist AF in mice was attempted.Methods and Results:This study used wild type (WT) mice, but it is difficult to induce AF in them. A novel antegrade perfusion method from the left ventricle (LV) to enlarge both atria for artificial atrial modification was proposed in this study. Short duration AF was induced by burst pacing under this method. Optical mapping analysis revealed non-sustained focal type and meandering spiral reentrants after short duration AF. A tiny artificial substrate (~1.2 mm in diameter) was added in by laser irradiation to create a critical atrial arrhythmogenic substrate. Burst pacing was performed in a non-laser group (n=8), a circular-shape laser group (n=8), and a wedge-shaped dent laser group (n=8). We defined AF and atrial tachycardia (AT) as atrial arrhythmia (AA). Long-lasting AA was defined as lasting for ≥30 min. Long-lasting AA was observed in 0/8, 0/8, and 6/8 (75%) mice in each group. Optical mapping analysis revealed that the mechanism was AT with a stationary rotor around the irradiated margin. Conclusions Regrettably, this study failed to reproduce persistent AF, but succeeded in creating an arrhythmic substrate that causes sustained AT in WT mice.

Heart failure (HF) is a syndrome with global clinical and socioeconomic burden worldwide owing to its poor prognosis. Accumulating evidence has implicated the possible contribution of gut microbiota-derived metabolites, short-chain fatty acids (SCFAs), on the pathology of a variety of diseases. The changes of SCFA concentration were reported to be observed in various cardiovascular diseases including HF in experimental animals and humans. HF causes hypoperfusion and/or congestion in the gut, which may lead to lowered production of SCFAs, possibly through the pathological changes of the gut microenvironment including microbiota composition. Recent studies suggest that SCFAs may play a significant role in the pathology of HF, possibly through an agonistic effect on G-protein-coupled receptors, histone deacetylases (HDACs) inhibition, restoration of mitochondrial function, amelioration of cardiac inflammatory response, its utilization as an energy source, and remote effect attributable to a protective effect on the other organs. Collectively, in the pathology of HF, SCFAs might play a significant role as a key mediator in the gut–heart axis. However, these possible mechanisms have not been entirely clarified and need further investigation.

Previous reports suggested that low subcutaneous adiposity increases the risk of cardiovascular events and diabetes. Mechanisms of depot-specific differences are still unknown. During studying tissue-specific roles of ERK2 (MAPK1), we observed Fabp4Cre mediated adipocyte-specific ERK2 knockout mice (AE2KO) with HFHS diet showed diminished the size of adipocytes in an only subcutaneous depot and increased ectopic fat depot and fibrotic steatohepatitis. The male AE2KO was created by crossing the C57BL/6 background Fabp4-Cre with ERK2flox/flox mouse. ERK2flox/flox Cre- mouse was used as a control. ERK2KO was observed only in white adipose tissues. With a normal diet, AE2KO mice showed no phenotype. HFHS diet started at age 6 weeks for 18 weeks. AE2KO exhibited 18% increase in body weight (n=8 each, p Disclosure Y. Ishinoda: None. T. Adachi: None. H. Kumagai: None. Y. Ido: None. M. Noguchi: None. Y. Yumita: None. K. Kagami: None. A. Osaki: None. Y. Satoh: None. S. Endo: None. A. Kasuga: None.

Delivering and expressing a gene of interest in cells or living animals has become a pivotal technique in biomedical research and gene therapy. Among viral delivery systems, adeno-associated viruses (AAVs) are relatively safe and demonstrate high gene transfer efficiency, low immunogenicity, stable long-term expression, and selective tissue tropism. Combined with modern gene technologies, such as cell-specific promoters, the Cre/lox system, and genome editing, AAVs represent a practical, rapid, and economical alternative to conditional knockout and transgenic mouse models. However, major obstacles remain for widespread AAV utilization, such as impractical purification strategies and low viral quantities. Here, we report an improved protocol to produce serotype-independent purified AAVs economically. Using a helper-free AAV system, we purified AAVs from HEK293T cell lysates and medium by polyethylene glycol precipitation with subsequent aqueous two-phase partitioning. Furthermore, we then implemented an iodixanol gradient purification, which resulted in preparations with purities adequate for in vivo use. Of note, we achieved titers of 1010–1011 viral genome copies per µl with a typical production volume of up to 1 ml while requiring five times less than the usual number of HEK293T cells used in standard protocols. For proof of concept, we verified in vivo transduction via Western blot, qPCR, luminescence, and immunohistochemistry. AAVs coding for glutaredoxin-1 (Glrx) shRNA successfully inhibited Glrx expression by ~66% in the liver and skeletal muscle. Our study provides an improved protocol for a more economical and efficient purified AAV preparation.

Background To obtain a saphenous vein graft (SVG) for coronary artery bypass grafting (CABG), the benefit of using a no-touch (NT) technique in vascular function has not been fully investigated. Methods and Results: The pathological and physiological functions of human SVGs with a NT technique to preserve the perivascular adipose tissue (PVAT) and ones obtained by using a conventional (CON) technique removing PVAT, were examined. Immunohistochemistry of the section of SVGs showed that the phosphorylation of endothelial nitric oxide synthase in the endothelium of the NT group was more responsive to vascular endothelial growth factor. A myograph of SVGs showed greater contraction with phenylephrine in the NT group. However, the strong contraction was eliminated in SVGs taken by electrocautery. In the 10 patients whose SVGs were taken without electrocautery, endothelial-dependent relaxation with bradykinin was apparently increased in the CON group more than in the NT group. Smooth muscle relaxation with nitroprusside was higher in the CON group at the lower concentrations; however, the relaxation became greater in the NT group at the high concentrations. Therefore, the effect of neutralizing PVAT-released factors in the both groups was further examined. After medium of NT and CON were exchanged in half, relaxation of SVGs was immediately restored in the NT group. Conclusions The results suggest that the NT technique preserves the functions of vasoconstriction and relaxation. Also, the presence of PVAT-released vasoconstrictive factors was suspected.

Superoxide dismutase (SOD) is an enzyme that catalyzes the dismutation of two superoxide anions (O2·−) into hydrogen peroxide (H2O2) and oxygen (O2) and is generally known to protect against oxidative stress. Angiotensin II (AngII) causes vascular hypertrophic remodeling which is associated with H2O2 generation. The aim of this study is to investigate the role of cytosolic SOD (SOD1) in AngII-induced vascular hypertrophy. We employed C57/BL6 mice (WT) and SOD1 deficient mice (SOD1−/−) with the same background. They received a continuous infusion of saline or AngII (3.2 mg/kg/day) for seven days. The blood pressures were equally elevated at 1.5 times with AngII, however, vascular hypertrophy was blunted in SOD1−/− mice compared to WT mice (WT mice 91.9 ± 1.13 µm versus SOD1−/− mice 68.4 ± 1.41 µm p &lt, 0.001). The elevation of aortic interleukin 6 (IL-6) and phosphorylation of pro-inflammatory STAT3 due to AngII were also blunted in SOD1−/− mice’s aortas. In cultured rat vascular smooth muscle cells (VSMCs), reducing expression of SOD1 with siRNA decreased AngII induced IL-6 release as well as phosphorylation of STAT3. Pre-incubation with polyethylene glycol (PEG)-catalase also attenuated phosphorylation of STAT3 due to AngII. These results indicate that SOD1 in VSMCs plays a role in vascular hypertrophy due to increased inflammation caused by AngII, probably via the production of cytosolic H2O2.

Introduction Extracellular signal-regulated kinase (ERK) modulates differentiation and maturation of adipocyte and the hypertrophy and differentiation of adipocytes affected the vascular diseases in obese. Changes in characters of adipocytes could develope the oxidative stress and inflammations. Moreover, changes in perivascular adipose tissue (PVAT) could modulate vascular tonus in obesity. However, the role of adipose ERK2 in endothelial function and characters of PVAT in obese in vivo had not been clarified, yet. Purpose This study aims to elucidate the role of the adipose ERK2 in endothelial-dependent relaxation (EDR) in mice model of obesity. The role of PVAT in EDR was also assessed. Methods and results We created adipose-specific ERK2 knock out mice (AE2KO) by crossing fatty acid binding protein 4 Cre and ERK2 flox mice and fed them with normal diet (ND) or high fat/ high sucrose diet (HFHSD) for 24 weeks. AE2KO fed with HFHSD gained more weight and revealed the heterogeneity in sizes of adipocyte in subcutaneous fat (SF). Furthermore, the mRNA levels of lipoprotein lipase, hormone-sensitive lipase, and peroxisome proliferator-activated receptor γ, which was the master genes of adipocyte differentiation, were markedly down-regulated in SF. PVAT in AE2KO with HFHSD was markedly enlarged and the mRNA expression of inflammatory adipocytokines, such as IL-1β and leptin were up-regulated. Next, we assessed EDR by acetylcholine (ACh) -induced relaxation in aortic rings with or without PVAT. EDR without PVAT was modestly decreased in AE2KO with HFHSD compared with wild type mice (WT) with HFHSD. Aortic rings with PVAT increased EDR in WT with ND. PVAT modestly decreased EDR in WT with HFHSD and mostly eliminated EDR in AE2KO with HFHSD. To assess the contraction factors released from PVAT, the solutions incubated with PVAT (SIP) were transferred to the normal aortic rings. SIP from WT with HFHSD mildly increased vascular tone and SIP from AE2KO with HFHSD further increased it. Tempol, which was superoxide scavenger, restored endothelial dysfunction with PVAT and suppressed the contraction with SIP from AE2KO with HFHSD. Fluorescence intensity of dihydroethidium stain of aorta and PVAT, which indicated that aortic and adipose superoxide production were elevated in AE2KO with HFHSD, which were mostly eliminated with tempol. Conclusions Adipose ERK2 selectively modulated differentiation in SF, suppressed the aortic oxidative stress and protected from endothelial dysfunction in obese. Moreover, adipose ERK2 suppressed the hypertrophy, inflammation, and oxidative stress of PVAT in obese. The oxidative stress with the inflammation in PVAT released vasoconstriction factors, which contributed to endothelial dysfunction in obese mice. Figure 1 Funding Acknowledgement Type of funding source: None

Background Sarcoplasmic reticulum Ca2+-ATPase2 (SERCA2) plays an important role in intracellular Ca2+ handling. Under pathological conditions, oxidative stress leads to irreversible oxidation of Cys674 on SERCA2 which causes intracellular Ca2+ overload. Intracellular Ca2+ overload is known as the cause of ventricular arrhythmia, but the relation between SERCA2 function and ventricular arrhythmia remains unclear. Purpose To investigate the role of Cys674 on SERCA2 in the intracellular Ca2+ handling and the induction of ventricular arrhythmia. Methods We employed SERCA2 Cys674Ser heterozygote knock-in mice (SKI) which mimics oxidative modification of Cys674 on SERCA2. Continuous infusion of angiotensin (ANG) (3mg/kg/day) or distilled water were performed both in wild type mice (WT) and SKI for a week. After 1 week, electrophysiological study and intracellular Ca2+ transient measurement were performed. Results ANG elevated blood pressure and represented cardiac hypertrophy with fibrosis similarly both in WT and SKI. The mRNA expression of calcium/calmodulin-dependent protein kinase-II (CaMKII), ryanodine receptor (RyR) and sodium-calcium exchanger (NCX) was increased in SKI heart compared with WT. QTc interval was prolonged in SKI compared with WT, which was markedly prolonged with ANG infusion. Under programmed electrical stimulation, only SKI with ANG showed high incidence of pacing induced ventricular arrhythmia (0/11 in WT/SKI control, 0/14 in WT with ANG vs. 8/14 in SKI with ANG, P Conclusions The loss of thiol on Cys674 under pathological condition resulted in impaired Ca2+ handling and high incidence of ventricular arrhythmia which were ameliorated by inhibition of Ca2+ leakage through RyR. Oxidative modification of Cys674 on SERCA2 might contribute to Ca2+ mishandling and arrhythmogenesis. Abstract Figure.

Previous reports have shown that excess calorie intake promotes p53 dependent senescence in mouse adipose tissues. The objective of the current study was to address the mechanism underlying this observation, i.e. adipocyte aging. Using cultured 3T3-L1 cells, we investigated the involvement of energy regulators Sirt1, AMPK, and LKB1 in senescence. Fifteen days post differentiation, Sirt1 knock-down increased senescence-associated beta-galactosidase (SA-β-Gal) staining by 20-40% (p

Background: Oxidative posttranslational modifications (OPTM) impair the function of Sarcoplasmic/endoplasmic reticulum (SR) calcium (Ca2+) ATPase (SERCA) 2 and trigger cytosolic Ca2+ dysregulation. We investigated the extent of OPTM of SERCA2 in patients with non-ischemic cardiomyopathy (NICM). Methods and results: Endomyocardial biopsy (EMB) was obtained in 40 consecutive patients with NICM. Total expression and OPTM of SERCA2, including sulfonylation at cysteine-674 (S-SERCA2) and nitration at tyrosine-294/295 (N-SERCA2), were examined by immunohistochemical analysis. S-SERCA2 increased in the presence of late gadolinium enhancement on cardiac magnetic resonance imaging. S-SERCA2/SERCA2 and N-SERCA2/SERCA2 correlated with cardiac fibrosis evaluated by Masson’s trichrome staining of EMB. SERCA2 expression modestly increased in parallel with an upward trend in OPTM of SERCA2 with aging. This tendency became prominent only in patients aged >65 years. OPTM of SERCA2 positively correlated with brain natriuretic peptide (BNP) values only in patients aged ≤65 years. Composite major adverse cardiac events (MACE) increased more in the high OPTM group of younger patients; however, MACE-free survival was similar irrespective of the extent of OPTM in older patients. Conclusions: OPTM of SERCA2 correlate with myocardial fibrosis in NICM. In younger patients, OPTM of SERCA2 correlate with elevated BNP and increased composite MACE. Keywords: SERCA2, Oxidative posttranslational modification, Myocardial fibrosis, Non-ischemic cardiomyopathy

We and others demonstrated that insulin C-peptide has biological activities and may prevent tissue damages by diabetes. Our research using STZ diabetic rats and other models suggested that diabetic vascular dysfunctions, e.g., increased vascular permeability and blood flows are caused by oxidative and nitrosative stress initiated from increased NADH redox (reductive stress). However, C-peptide prevented dysfunctions without normalizing redox state and worked in nondiabetic rats. In this study, we further examined modes of actions and investigated its mechanisms. Male Wistar rats were used in animal study. Human de-differentiated adipocytes (DFAT cells) were used for cell culture study. Lentivirus vector expressing LC3-GFP was created to assess autophagy. Regional blood flow was assessed using microsphere. Acute hyperglycemia induced by glucose infusion for 5 hours resulted in increased regional blood flows in retina, sciatic nerve and kidney. Simultaneous infusion of C-peptide up to 16 mg/kg did not prevent the increases, while twice daily subcutaneous injection of 400 µg/kg for 2-days prior to infusion prevented completely. One-day injection was only slightly effective. Bolus i.v. injection of L-lactate 1 mol/kg but not NaCl caused reductive stress and blood flow increase, and this was also prevented by twice daily 2-days injection of C-peptide. Thus, C-peptide appeared to induce some factors counteracting oxidative stress during 2 days. In DFAT cells, LC3-GFP puncta was increased 3-fold by one time 100 nM C-peptide treatment in 1 hour. This was followed by nuclear localization of Nrf2 transcription factor at 2 hours. At 4 hour, 4-fold increase in Nrf2 target genes, IDH and SRXN1, expression were observed (p Disclosure F. Lan: None. Y. Lin: None. Z. Gao: None. P. Zhao: None. X. Zhang: None. Y. Shiraishi: None. Y. Ido: None. Funding Japan Society for the Promotion of Science

Background Endothelial insulin resistance is insulin‐insensitivity in the vascular endothelium and can be observed in experimental models. This study aimed to investigate endothelial insulin resistance in patients with suspected coronary artery disease. To this end, a novel method of obtaining freshly isolated arterial endothelial cells from a radial catheter sheath was developed. Methods and Results Freshly isolated arterial endothelial cells were retrieved from catheter sheaths placed in radial arteries for coronary angiography (n=69, patient age 64±12 years). The endothelial cells were divided into groups for incubation with or without insulin, vascular endothelial growth factor, or acetylcholine. The intensity of phosphorylated endothelial nitric oxide synthase at Ser1177 (p‐ eNOS ) was quantified by immunofluorescence microscopy. The percentage increase of insulin‐induced phosphorylated endothelial nitric oxide synthase correlated negatively with derivatives of reactive oxygen metabolites, an oxidative stress test ( r =−0.348, n=53, P =0.011), E/E′, an index of left ventricular diastolic dysfunction in Doppler echocardiography (ρ=−0.374, n=49, P =0.008), and log‐transformed brain natriuretic peptide ( r =−0.266, n=62, P =0.037). Furthermore, percentage increase of insulin‐induced p‐ eNOS was an independent factor for the cardio‐ankle vascular index (standardized coefficient β=−0.293, n=42, P =0.021) in the multivariate regression analysis of adaptive least absolute shrinkage and selection operator. Conclusions Our results suggested that endothelial insulin resistance is associated with oxidative stress, left ventricular diastolic dysfunction, heart failure, and arterial stiffness.

Periodic echo-based screening to detect early stages of a rare complication of dasatinib, pulmonary arterial hypertension (PAH), is inefficient and weakens the potential benefit of dasatinib as a potent drug for chronic myelogenous leukemia (CML). This study aimed to identify the predisposing factors of DASA-PAH to stratify high-risk patients for dasatinib-induced PAH (DASA-PAH). Sixty consecutive adult patients who received dasatinib were enrolled in this case-control study. We defined DASA-PAH when at least one of the following four criteria was met: (1) recent electrocardiographic changes indicating right ventricular pressure overload, (2) estimated systolic pulmonary arterial pressure > 40 mmHg measured by Doppler echocardiography; (3) computed tomography (CT)-measured pulmonary artery to aorta diameter (PaD/AoD) ratio > 1; and (4) mean pulmonary arterial pressure > 25 mmHg and pulmonary artery wedge pressure

Reactive oxygen species (ROS) are increased in ischemic tissues and necessary for revascularization; however, the mechanism remains unclear. Exposure of cysteine residues to ROS in the presence of glutathione (GSH) generates GSH-protein adducts that are specifically reversed by the cytosolic thioltransferase, glutaredoxin-1 (Glrx). Here, we show that a key angiogenic transcriptional factor hypoxia-inducible factor (HIF)-1α is stabilized by GSH adducts, and the genetic deletion of Glrx improves ischemic revascularization. In mouse muscle C2C12 cells, HIF-1α protein levels are increased by increasing GSH adducts with cell-permeable oxidized GSH (GSSG-ethyl ester) or 2-acetylamino-3-[4-(2-acetylamino-2-carboxyethylsulfanyl thiocarbonylamino) phenylthiocarbamoylsulfanyl] propionic acid (2-AAPA), an inhibitor of glutathione reductase. A biotin switch assay shows that GSSG-ester-induced HIF-1α contains reversibly modified thiols, and MS confirms GSH adducts on Cys(520) (mouse Cys(533)). In addition, an HIF-1α Cys(520) serine mutant is resistant to 2-AAPA-induced HIF-1α stabilization. Furthermore, Glrx overexpression prevents HIF-1α stabilization, whereas Glrx ablation by siRNA increases HIF-1α protein and expression of downstream angiogenic genes. Blood flow recovery after femoral artery ligation is significantly improved in Glrx KO mice, associated with increased levels of GSH-protein adducts, capillary density, vascular endothelial growth factor (VEGF)-A, and HIF-1α in the ischemic muscles. Therefore, Glrx ablation stabilizes HIF-1α by increasing GSH adducts on Cys(520) promoting in vivo HIF-1α stabilization, VEGF-A production, and revascularization in the ischemic muscles.

Recent research in nutritional control of aging suggests that cytosolic increases in the reduced form of nicotinamide adenine dinucleotide and decreasing nicotinamide adenine dinucleotide metabolism plays a central role in controlling the longevity gene products sirtuin 1 (SIRT1), adenosine monophosphate‐activated protein kinase (AMPK) and forkhead box O3 (FOXO3). High nutrition conditions, such as the diabetic milieu, increase the ratio of reduced to oxidized forms of cytosolic nicotinamide adenine dinucleotide through cascades including the polyol pathway. This redox change is associated with insulin resistance and the development of diabetic complications, and might be counteracted by insulin C‐peptide. My research and others' suggest that the SIRT1–liver kinase B1–AMPK cascade creates positive feedback through nicotinamide adenine dinucleotide synthesis to help cells cope with metabolic stress. SIRT1 and AMPK can upregulate liver kinase B1 and FOXO3, key factors that help residential stem cells cope with oxidative stress. FOXO3 directly changes epigenetics around transcription start sites, maintaining the health of stem cells. ‘Diabetic memory’ is likely a result of epigenetic changes caused by high nutritional conditions, which disturb the quiescent state of residential stem cells and impair tissue repair. This could be prevented by restoring SIRT1–AMPK positive feedback through activating FOXO3.

Dysregulated autophagy and decreased AMP-activated protein kinase (AMPK) activity are each associated with atherogenesis. Atherogenesis is preceded by high circulating concentrations of glucose and fatty acids, yet the mechanism by which these nutrients regulate autophagy in human aortic endothelial cells (HAECs) is not known. Furthermore, whereas AMPK is recognized as an activator of autophagy in cells with few nutrients, its effects on autophagy in nutrient-rich HAECs has not been investigated. We maintained and passaged primary HAECs in media containing 25 mM glucose and incubated them subsequently with 0.4 mM palmitate. These conditions impaired basal autophagy and rendered HAECs more susceptible to apoptosis and adhesion of monocytes, outcomes attenuated by the autophagy activator rapamycin. Glucose and palmitate diminished AMPK activity and phosphorylation of the uncoordinated-51-like kinase 1 (ULK1) at Ser555, an autophagy-activating site targeted by AMPK. 5-Aminoimidazole-4-carboxamide-1-β-d-ribofuranoside (AICAR)-mediated activation of AMPK phosphorylated acetyl-CoA carboxylase, but treatment with AICAR or other AMPK activators (A769662, phenformin) did not restore ULK1 phosphorylation or autophagosome formation. To determine whether palmitate-induced ceramide accumulation contributed to this finding, we overexpressed a ceramide-metabolizing enzyme, acid ceramidase. The increase in acid ceramidase expression ameliorated the effects of excess nutrients on ULK1 phosphorylation, without altering the effects of the AMPK activators. Thus, unlike low nutrient conditions, AMPK becomes uncoupled from autophagy in HAECs in a nutrient-rich environment, such as that found in patients with increased cardiovascular risk. These findings suggest that combinations of AMPK-independent and AMPK-dependent therapies may be more effective alternatives than either therapy alone for treating nutrient-induced cellular dysfunction.

In adipocytes, lipolysis is a highly regulated process involving hormonal signals, lipid droplet-associated proteins, and lipases. The discovery of new lipid droplet-associated proteins added complexity to the current model of lipolysis. In this study, we used cultured human adipocytes to demonstrate that fat-specific protein 27 (FSP27), an abundantly expressed protein in adipocytes, regulates both basal and stimulated lipolysis by interacting with adipose triglyceride lipase (ATGL, also called desnutrin or PNPLA2). We identified a core domain of FSP27, amino acids 120-220, that interacts with ATGL to inhibit its lipolytic function and promote triglyceride storage. We also defined the role of FSP27 in free fatty acid-induced insulin resistance in adipocytes. FSP27 depletion in human adipocytes increased lipolysis and inhibited insulin signaling by decreasing AKT phosphorylation. However, reducing lipolysis by either depletion of ATGL or expression of exogenous full-length FSP27 or amino acids 120-220 protected human adipocytes against the adverse effects of free fatty acids on insulin signaling. In embryonic fibroblasts derived from ATGL KO mice, exogenous free fatty acids did not affect insulin sensitivity. Our results demonstrate a crucial role for FSP27-ATGL interactions in regulating lipolysis, triglyceride accumulation, and insulin signaling in human adipocytes.

Oxidative stress is pathogenic in a variety of diseases, but the mechanism by which cellular signaling is affected by oxidative species has yet to be fully characterized. Lipid peroxidation, a secondary process that occurs during instances of free radical production, may play an important role in modulating cellular signaling under conditions of oxidative stress. 4-Hydroxy-trans-2-nonenal (HNE) is an electrophilic aldehyde produced during lipid peroxidation that forms covalent adducts on proteins, altering their activity and function. One such target, LKB1, has been reported to be inhibited by HNE adduction. We tested the hypothesis that HNE inhibits LKB1 activity through adduct formation on a specific reactive residue of the protein. To elucidate the mechanism of the inhibitory effect, HEK293T cells expressing LKB1 were treated with HNE (10 μm for 1 h) and assayed for HNE-LKB1 adduct formation and changes in LKB1 kinase activity. HNE treatment resulted in the formation of HNE-LKB1 adducts and decreased LKB1 kinase activity by 31 ± 9% (S.E.) but had no effect on the association of LKB1 with its adaptor proteins sterile-20-related adaptor and mouse protein 25. Mutation of LKB1 lysine residue 97 reduced HNE adduct formation and attenuated the effect of HNE on LKB1 activity. Taken together, our results suggest that adduction of LKB1 Lys-97 mediates the inhibitory effect of HNE.

Suppression of the enzyme glycogen synthase kinase 3β (GSK3β) increases both the turnover of damaged cellular material and the activity of the enzyme AMP-activated protein kinase (AMPK) to potentially attenuate the damage inflicted by excess sugar and fat on blood vessels., High concentrations of glucose and palmitate increase endothelial cell inflammation and apoptosis, events that often precede atherogenesis. They may do so by decreasing basal autophagy and AMP-activated protein kinase (AMPK) activity, although the mechanisms by which this occurs are not clear. Decreased function of the lysosome, an organelle required for autophagy and AMPK, have been associated with hyperactivity of glycogen synthase kinase 3β (GSK3β). To determine whether GSK3β affects nutrient-induced changes in autophagy and AMPK activity, we used a primary human aortic endothelial cell (HAEC) model of type 2 diabetes that we had previously characterized with impaired AMPK activity and autophagy [Weikel et al. (2015) Am. J. Phys. Cell Physiol. 308, C249–C263]. Presently, we found that incubation of HAECs with excess nutrients (25 mM glucose and 0.4 mM palmitate) increased GSK3β activity and impaired lysosome acidification. Suppression of GSK3β in these cells by treatment with a chemical inhibitor or overexpression of kinase-dead GSK3β attenuated these lysosomal changes. Under control and excess nutrient conditions, knockdown of GSK3β increased autophagosome formation, forkhead box protein O1 (FOXO1) activity and AMPK signalling and decreased Akt signalling. Similar changes in autophagy, AMPK and Akt signalling were observed in aortas from mice treated with the GSK3β inhibitor CHIR 99021. Thus, increasing basal autophagy and AMPK activity by inhibiting GSK3β may be an effective strategy in the setting of hyperglycaemia and dyslipidaemia for restoring endothelial cell health and reducing atherogenesis.

Increased adipocyte size is hypothesized to signal the recruitment of adipose progenitor cells (APCs) to expand tissue storage capacity. To investigate depot and sex differences in adipose growth, male and female C57BL/6J mice (10 wk-old) were challenged with high-fat (HF) or low-fat (LF) diets (D) for 14 wk. The HFD increased gonadal (GON) depot weight by adipocyte hypertrophy and hyperplasia in females but hypertrophy alone in males. In both sexes, inguinal (ING) adipocytes were smaller than GON, and depot expansion was due to hypertrophy. Matrix metalloproteinase 3 (Mmp3), an antiadipogenic factor, and its inhibitor Timps modulate the extracellular matrix remodeling needed for depot expansion. Mmp3 mRNA was depot different (ING > GON), higher in females than males and mainly expressed in APCs. In males, HFD-induced obesity increased tissue and APC Mmp3 mRNA levels and MMP3 protein and enzymatic activity. In females however, HFD significantly decreased MMP3 protein without affecting its mRNA levels. MMP3 activity also decreased (significant in ING). Timp4 mRNA was expressed mainly in adipocytes, and HFD-induced obesity tended to increase the ratio of TIMP4 to MMP3 protein in females, whereas it decreased it in males. Overexpression of Mmp3 in 3T3-L1 preadipocytes or rhMMP3 protein added to primary human preadipocytes inhibited differentiation, whereas rhTIMP4 improved adipogenesis and attenuated the inhibitory effect of rhMMP3. These data suggest that HFD-induced obesity downregulates APC MMP3 expression to trigger adipogenesis, and adipocyte TIMP4 may modulate this process to regulate hyperplastic vs. hypertrophic adipose tissue expansion, fat distribution, and metabolic health in a sex- and depot-dependent manner.

Exercise can prevent endothelial cell (EC) dysfunction and atherosclerosis even in the absence of improvements in plasma lipids. However, the mechanisms responsible for these effects are incompletely understood. In this study we examined in mice whether an acute bout of exercise activates enzymes that could prevent EC dysfunction, such as AMP-activated protein kinase (AMPK) and endothelial nitric oxide synthase (eNOS). We also examined whether exercise alters known regulators of these enzymes. C57BL/6 mice underwent a single bout of exhaustive treadmill exercise after which their aortas were analyzed for activation of AMPK, AMPK regulatory proteins, eNOS, and various enzymes that, like AMPK, activate eNOS. We found that such exercise acutely activates both AMPK and eNOS in the whole aorta and that the magnitude of these effects correlated with both the distance run and activation of the AMPK regulatory proteins silent information regulator-1 (SIRT1)-LKB1 and CaMKKβ. In contrast, Akt, PKA, PKG, and Src, other kinases known to activate eNOS, were unaffected. Immunohistochemical analysis revealed that AMPK and eNOS were both activated in the ECs of the aorta. This study provides the first evidence that an acute bout of exercise activates AMPK and eNOS in the endothelium of the aorta. The results also suggest that AMPK likely is the principal activator of eNOS in this setting and that its own activation may be mediated by both SIRT1-LKB1 and CaMKKβ.

Glutaredoxin-1 (Glrx) is a cytosolic enzyme that reverses glutathione (GSH) adducts of protein thiols generated through oxidative post-translational modifications. GSH-adducts regulate cellular signaling and transcription factors. We previously found that after femoral artery ligation Glrx knockout mice improved blood flow recovery in relation to activation of hypoxia-inducible factor (HIF)-1α via GSH adducts, indicating Glrx as an anti-angiogenic enzyme. Objective We hypothesized that local Glrx gene inhibition might improve poor blood flow recovery after ischemia in aging or diabetes. To inhibit Glrx gene expression in vitro and in vivo, we developed an improved protocol to produce adeno-associated viruses (AAVs) with a bicistronic expression system coding for Glrx shRNA (shGlrx) and mVenus, a yellow fluorescent protein. Methods Using a helper-free AAV system, we purified AAVs from HEK293T cell lysates and medium by polyethylene glycol precipitation, aqueous two-phase partitioning, and an iodixanol gradient, which resulted in AAVs with adequate titer and purity for in vivo use. We tested the AAVs on C2C12 skeletal muscle cells and mouse gastrocnemius muscles. Results Quiescent confluent C2C12 cells transduced with a shGlrx-containing AAV exhibited a decrease of ~75% in the Glrx mRNA and protein levels after 4 days. Intramuscular injection (4.4 x 1012 viral genome/50 μl) of AAV-shGlrx transduced mVenus expression in skeletal muscle efficiently, but non-injected muscle, heart, or liver showed no mVenus expression. However, 4 weeks after intramuscular injection, Glrx protein levels remained unchanged compared to control-AAV injected or non-injected muscle, and inflammatory markers were increased. Six weeks after virus injection, Glrx expression in the muscle decreased 80% at the mRNA and 50% at the protein level. Conclusion Intramuscular injection of AAV-shGlrx resulted in muscle-specific attenuation of Glrx expression after at least 6 weeks. AAV intramuscular injection caused local inflammation in the early stage which may counteract the effects of shGlrx. (R01HL133013, R03AG051857, R01DK103750)

AMP-activated protein kinase (AMPK) and the histone/protein deacetylase SIRT1 are fuel-sensing molecules that have coexisted in cells throughout evolution. When a cell's energy state is diminished, AMPK activation restores energy balance by stimulating catabolic processes that generate ATP and downregulating anabolic processes that consume ATP but are not acutely needed for survival. SIRT1 in turn is best known historically for producing genetic changes that mediate the increase in longevity caused by calorie restriction. Although the two molecules have been studied intensively for many years, only recently has it become apparent that they have similar effects on diverse processes such as cellular fuel metabolism, inflammation, and mitochondrial function. In this review we will examine the evidence that these similarities occur because AMPK and SIRT1 both regulate each other and share many common target molecules. In addition, we will discuss the clinical relevance of these interactions and in particular the possibility that their dysregulation predisposes to disorders such as type 2 diabetes and atherosclerotic cardiovascular disease and is a target for their therapy.

The preservation of perivascular fat is suggested to contribute to improvement of patency of saphenous vein graft (SVG) in coronary artery bypass grafting (CABG). This study examined the influence of perivascular fat on vascular tonus in SVG used for CABG using ex-vivo isometric tension measurement

We examined in HepG2 cells whether glucose-induced changes in AMP-activated protein kinase (AMPK) activity could be mediated by SIRT1, an NAD-dependent histone/protein deacetylase that has been linked to the increase in longevity caused by caloric restriction. Incubation with 25 vs. 5 mM glucose for 6 h concurrently diminished the phosphorylation of AMPK (Thr 172) and ACC (Ser 79), increased lactate release, and decreased the abundance and activity of SIRT1. In contrast, incubation with pyruvate (0.1 and 1 mM) for 2 h increased AMPK phosphorylation and SIRT1 abundance and activity. The putative SIRT1 activators resveratrol and quercetin also increased AMPK phosphorylation. None of the tested compounds (low or high glucose, pyruvate, and resveratrol) significantly altered the AMP/ATP ratio. Collectively, these findings raise the possibility that glucose-induced changes in AMPK are linked to alterations in SIRT1 abundance and activity and possibly cellular redox state.

SIRT1, a histone/protein deacetylase, and AMP-activated protein kinase (AMPK) are key enzymes responsible for longevity and energy homeostasis. We examined whether a mechanistic connection exists between these molecules that involves the major AMPK kinase LKB1. Initial studies demonstrated that LKB1 is acetylated in cultured (HEK293T) cells, mouse white adipose tissue, and rat liver. In the 293T cells, SIRT1 overexpression diminished lysine acetylation of LKB1 and concurrently increased its activity, cytoplasmic/nuclear ratio, and association with the LKB1 activator STRAD. In contrast, short hairpin RNA for SIRT1, where studied, had opposite effects on these parameters. Mass spectrometric analysis established that acetylation of LKB1 occurs on multiple, but specific, lysine residues; however, only mutation of lysine 48 to arginine, which mimics deacetylation, reproduced all of the effects of activated SIRT1. SIRT1 also affected downstream targets of LKB1. Thus its overexpression increased AMPK and acetyl-CoA carboxylase phosphorylation, and conversely, RNA interference-mediated SIRT1 knockdown reduced AMPK phosphorylation and that of another LKB1 target MARK1. Consistent with the results in cultured cells, total LKB1 lysine acetylation was decreased by 60% in the liver of 48-h starved rats compared with starved-refed rats, and this was associated with modest but significant increases in both LKB1 and AMPK activities. These results suggest that LKB1 deacetylation is regulated by SIRT1 and that this in turn influences its intracellular localization, association with STRAD, kinase activity, and ability to activate AMPK.

In addition to hyperglycemia, diabetes is associated with increased levels of circulating free fatty acids, lactate, and branched chain amino acids, all of which produce an excessive reduced form of pyridine nucleotides NADH (reductive stress) in the cytosol and mitochondria. Our studies suggest that cytosolic NADH reductive stress under high glucose is largely caused by increased flux of glucose through polyol (sorbitol) pathway consisting of aldose reductase and sorbitol dehydrogenase. Inhibition of aldose reductase that blocks the polyol pathway has been shown to ameliorate diabetic neuropathy in humans. Cytosolic NADH reductive stress is predicted to increase production of diglycerides, reactive oxygen species, and methylglyoxal. Recent studies indicate that increasing NADH affects gene expression through the NADH activating transcriptional co-repressor, C-terminal binding protein (CtBP). In addition, it has been shown that the NADH utilizing enzyme, glyceraldehyde-3-phosphate dehydrogenase, participates as transcriptional regulator. These findings testify to the importance of NADH redox balance in cell biology and pathogenesis of diabetes and its complications. For example, through CtBP, the high NADH to NAD(+) ratio decreases an expression of SirT1, the protein inducing longevity and anti-apoptosis. This review covers metabolic cascades causing reductive stress and oxidative stress in diabetes after a brief introduction of the redox concept.

Although reactive oxygen species (ROS) appear to play a central role in mediating myocardial hypertrophy in response to hemodynamic overload, little is known about the molecular targets by which ROS regulate growth signaling. In cardiac myocytes, we tested the hypothesis that mechanical strain causes cellular hypertrophy via ROS-dependent post-translational modification of Ras leading to activation of the Raf/Mek/Erk growth pathway. Cyclic mechanical strain increased Ras activity by 1.5 to 1.6-fold. Adenoviral overexpression of the N17 dominant negative mutant of Ras inhibited strain-stimulated Erk activation and protein synthesis. Strain-stimulated Ras activation was inhibited by overexpression of catalase, indicating that it is redox-dependent. Strain caused S-glutathiolation of Ras, which was inhibited by catalase overexpression and reversed by DTT. MALDI-TOF mass spectrometry demonstrated that in myocytes subjected to strain there was S-glutathiolation of Ras at Cys118. Adenoviral overexpression of a mutated Ras in which Cys118 was substituted with serine inhibited strain-stimulated S-glutathiolation of Ras, Erk activation and protein synthesis. Overexpression of glutaredoxin-1 likewise inhibited strain-stimulated Ras S-glutathiolation, Ras activation, Erk activation and protein synthesis. These findings indicate that mechanical strain causes ROS-dependent S-glutathiolation of Ras at Cys118, leading to myocyte hypertrophy via activation of the Raf/Mek/Erk pathway.

Sustained hyperglycemia impairs insulin-stimulated glucose utilization and glycogen synthesis in human and rat skeletal muscles, a phenomenon referred to clinically as glucose toxicity. In rat extensor digitorum longus (EDL) muscle preparations preincubated for 2-4 h in a hyperglycemic medium (25 mM vs. 0 mM glucose), we have shown that the ability of insulin to stimulate glucose incorporation into glycogen is impaired. Interestingly, this was associated with a decreased activation of Akt/PKB, but not its upstream regulator, PI3-kinase. A similar pattern of signaling abnormalities has been observed in adipocytes, L6 muscle cells, C2C12 cells, and (as reported here) EDL incubated with C(2)-ceramide. On the other hand, no increase was observed in ceramide mass in EDL incubated with 25 mM glucose. Hyperglycemia-induced insulin resistance also has been described in adipocytes, where it has been linked to activation of novel and conventional protein kinase C isoforms that phosphorylate the insulin receptor and IRS. In addition, we have recently shown that hyperglycemia causes insulin resistance in cultured human umbilical vein endothelial cells (HUVEC). Here, it was associated with an increased propensity to apoptosis and, as in muscle, with an impaired ability of insulin to activate Akt. Interestingly, these effects of hyperglycemia and an increase in diacylglycerol synthesis, which is also caused, were prevented by adding AICAR, an activator of AMP-activated protein kinase (AMPK), to the incubation medium. These results suggest that hyperglycemia causes insulin resistance in cells other than those in classic insulin target tissues. Whether AMPK activation can reverse or prevent insulin resistance in all of these cells remains to be determined.