Chronic inhibition of epidermal growth factor receptor tyrosine kinase and extracellular signal-regulated kinases 1 and 2 (ERK1/2) augments vascular response to limb ischemia in type 2 diabetic mice

Exploring putative drug properties associated with TNF-alpha inhibition and identification of potential targets in cardiovascular disease using machine learning-assisted QSAR modeling and virtual reverse pharmacology approach

Cardiovascular disease is a chronic inflammatory disease with high mortality rates. TNF-alpha is pro-inflammatory and associated with the disease, but current medications have adverse effects. Therefore, efficient inhibitors are urgently needed as alternatives. This study represents a structural-activity relationship investigation of TNF-alpha, curated from the ChEMBL database. Exploratory data analysis was performed to visualize the physicochemical properties of different bioactivity groups. The extracted molecules were subjected to PubChem and SubStructure fingerprints, and a QSAR-based Random Forest (QSAR-RF) model was generated using the WEKA tool. The QSAR random Forest model was built based on the SubStructure fingerprint with a correlation coefficient of 0.992 and 0.716 as the respective tenfold cross-validation scores. The variance important plot (VIP) method was used to extract the important features for TNF-alpha inhibition. The Substructure-based QSAR-RF (SS-QSAR-RF) model was validated using molecules from PubChem and ZINC databases. The generated model also predicts the pIC50 value of the molecules selected from the docking study followed by molecular dynamic simulation with the time step of 100 ns. Through virtual reverse pharmacology, we determined the main drug targets from the top four hit compounds obtained via molecular docking study. Our analysis included an integrated bioinformatics approach to pinpoint crucial targets like EGRF, HSP900A1, STAT3, PSEN1, AKT1, and MDM2. Further, GO and KEGG pathways analysis identified relevant cardiovascular disease-related pathways for the hub gene involved. However, this study provides valuable insights, it is important to note that it lacks experimental application. Future research may benefit from conducting in-vitro and in-vivo studies.

EGFR inhibition leads to enhanced desmosome assembly and cardiomyocyte cohesion via ROCK activation

Arrhythmogenic cardiomyopathy (AC) is a familial heart disease partly caused by impaired desmosome turnover. Thus, stabilization of desmosome integrity may provide new treatment options. Desmosomes, apart from cellular cohesion, provide the structural framework of a signaling hub. Here, we investigated the role of the epidermal growth factor receptor (EGFR) in cardiomyocyte cohesion. We inhibited EGFR under physiological and pathophysiological conditions using the murine plakoglobin-KO AC model, in which EGFR was upregulated. EGFR inhibition enhanced cardiomyocyte cohesion. Immunoprecipitation showed an interaction of EGFR and desmoglein 2 (DSG2). Immunostaining and atomic force microscopy (AFM) revealed enhanced DSG2 localization and binding at cell borders upon EGFR inhibition. Enhanced area composita length and desmosome assembly were observed upon EGFR inhibition, confirmed by enhanced DSG2 and desmoplakin (DP) recruitment to cell borders. PamGene Kinase assay performed in HL-1 cardiomyocytes treated with erlotinib, an EGFR inhibitor, revealed upregulation of Rho-associated protein kinase (ROCK). Erlotinib-mediated desmosome assembly and cardiomyocyte cohesion were abolished upon ROCK inhibition. Thus, inhibiting EGFR and, thereby, stabilizing desmosome integrity via ROCK might provide treatment options for AC.

Disrupting Interleukin 12 Improves Microvascular Endothelial Function in Type 2 Diabetes Through ER Stress CHOP and Oxidative Stress Mechanisms

PURPOSE

Vascular endothelial dysfunction is well established in type 2 diabetes. Interleukin-12 (IL-12) and endoplasmic reticulum (ER) stress are up-regulated in type 2 diabetic patients and animal models of type 2 diabetes. However, the role and underlying mechanisms of IL-12 and the ER stress CHOP in endothelial dysfunction are not fully understood.

METHODS

We generated double knockout mice between db^-/db^- and p40IL-12^-/- mice (db^-/db^{-p40-IL-12-/-}) and endoplasmic (ER) stress-CHOP^-/- mice (db^-/db^-CHOP-/-). We performed a glucose tolerance test (GTT) to determine the effect of IL-12 and ER stress CHOP on glucose metabolism. We assessed the endothelial function and determined the phosphorylation level of eNOS, Akt, AMPK, and the expression of ER stress (CHOP, BIP), and oxidative stress (Nox2 and Nox4 and NADPH oxidase activity).

RESULTS

The results showed that GTT was improved in db-/db^{-p40-IL-12-/-} and db^-/db^-CHOP-/- suggesting IL-12 and CHOP as parts of a mechanism involved in the development of type 2 diabetes. The microvascular endothelial dysfunction in db^-/db^- mouse is associated with decreased phosphorylated eNOS, Akt, AMPK, and increased CHOP, BIP, Nox2, and Nox4 expressions. Interestingly, disrupting IL-12 and ER stress CHOP in db^-/db^- mice significantly improved endothelial function, increased survival markers expression and decreased ER and oxidative stress.

CONCLUSION

Using a genetic approach, these findings provide evidence that IL-12 and ER stress CHOP play a significant role in microvascular endothelial dysfunction in type 2 diabetes.

The Role of Epidermal Growth Factor Receptor Family of Receptor Tyrosine Kinases in Mediating Diabetes-Induced Cardiovascular Complications

Diabetes mellitus is a major debilitating disease whose global incidence is progressively increasing with currently over 463 million adult sufferers and this figure will likely reach over 700 million by the year 2045. It is the complications of diabetes such as cardiovascular, renal, neuronal and ocular dysfunction that lead to increased patient morbidity and mortality. Of these, cardiovascular complications that can result in stroke and cardiomyopathies are 2- to 5-fold more likely in diabetes but the underlying mechanisms involved in their development are not fully understood. Emerging research suggests that members of the Epidermal Growth Factor Receptor (EGFR/ErbB/HER) family of tyrosine kinases can have a dual role in that they are beneficially required for normal development and physiological functioning of the cardiovascular system (CVS) as well as in salvage pathways following acute cardiac ischemia/reperfusion injury but their chronic dysregulation may also be intricately involved in mediating diabetes-induced cardiovascular pathologies. Here we review the evidence for EGFR/ErbB/HER receptors in mediating these dual roles in the CVS and also discuss their potential interplay with the Renin-Angiotensin-Aldosterone System heptapeptide, Angiotensin-(1-7), as well the arachidonic acid metabolite, 20-HETE (20-hydroxy-5, 8, 11, 14-eicosatetraenoic acid). A greater understanding of the multi-faceted roles of EGFR/ErbB/HER family of tyrosine kinases and their interplay with other key modulators of cardiovascular function could facilitate the development of novel therapeutic strategies for treating diabetes-induced cardiovascular complications.

Transgelin-2 as a therapeutic target for asthmatic pulmonary resistance

There is a clinical need for new bronchodilator drugs in asthma, because more than half of asthmatic patients do not receive adequate control with current available treatments. We report that inhibition of metallothionein-2 protein expression in lung tissues causes the increase of pulmonary resistance. Conversely, metallothionein-2 protein is more effective than β₂-agonists in reducing pulmonary resistance in rodent asthma models, alleviating tension in tracheal spirals, and relaxing airway smooth muscle cells (ASMCs). Metallothionein-2 relaxes ASMCs via transgelin-2 (TG2) and induces dephosphorylation of myosin phosphatase target subunit 1 (MYPT1). We identify TSG12 as a nontoxic, specific TG2-agonist that relaxes ASMCs and reduces asthmatic pulmonary resistance. In vivo, TSG12 reduces pulmonary resistance in both ovalbumin- and house dust mite-induced asthma in mice. TSG12 induces RhoA phosphorylation, thereby inactivating the RhoA-ROCK-MYPT1-MLC pathway and causing ASMCs relaxation. TSG12 is more effective than β₂-agonists in relaxing human ASMCs and pulmonary resistance with potential clinical advantages. These results suggest that TSG12 could be a promising therapeutic approach for treating asthma.

Essential role for EGFR tyrosine kinase and ER stress in myocardial infarction in type 2 diabetes

We previously reported that EGFR tyrosine kinase (EGFRtk) activity and endoplasmic reticulum (ER) stress are enhanced in type 2 diabetic (T2D) mice and cause vascular dysfunction. In the present study, we determined the in vivo contribution of EGFRtk and ER stress in acute myocardial infarction induced by acute ischemia (40 min)-reperfusion (24 h) (I/R) injury in T2D (db^-/db^-) mice. We treated db^-/db^- mice with EGFRtk inhibitor (AG1478, 10 mg/kg/day) for 2 weeks. Mice were then subjected to myocardial I/R injury. The db^-/db^- mice developed a significant infarct after I/R injury. The inhibition of EGFRtk significantly reduced the infarct size and ER stress induction. We also determined that the inhibition of ER stress (tauroursodeoxycholic acid, TUDCA, 150 mg/kg per day) in db^-/db^- significantly decrease the infarct size indicating that ER stress is a downstream mechanism to EGFRtk. Moreover, AG1478 and TUDCA reduced myocardium p38 and ERK1/2 MAP-kinases activity, and increased the activity of the pro-survival signaling cascade Akt. Additionally, the inhibition of EGFRtk and ER stress reduced cell apoptosis and the inflammation as indicated by the reduction in macrophages and neutrophil infiltration. We determined for the first time that the inhibition of EGFRtk protects T2D heart against I/R injury through ER stress-dependent mechanism. The cardioprotective effect of EGFRtk and ER stress inhibition involves the activation of survival pathway, and inhibition of apoptosis, and inflammation. Thus, targeting EGFRtk and ER stress has the potential for therapy to overcome myocardial infarction in T2D.

Essential Role of IL-12 in Angiogenesis in Type 2 Diabetes

Recently, IL-12 emerged as a critical player in type 2 diabetes complications. We previously reported that ischemia-induced angiogenesis is compromised in type 2 diabetic mice. In this study, we determined that IL-12 disruption rescued angiogenesis and arteriogenesis in type 2 diabetic mice. To induce type 2 diabetes, wild-type (WT), p40IL-12^-/- (p40^-/-), and p35IL-12^-/- (p35^-/-) mice were fed a high-fat diet (HFD) for 12 weeks. Body weight, glucose test tolerance, and insulin test tolerance were assessed. After 12 weeks of an HFD, the femoral artery was ligated and blood flow recovery was measured every week for 4 weeks. WT, p40^-/-, and p35^-/- mice fed an HFD become obese after 12 weeks and exhibit glucose intolerance and insulin resistance. Blood flow recovery was fully restored in 2 to 3 weeks after femoral artery ligation in all groups of mice fed a normal diet. However, after 12 weeks of an HFD, blood flow recovery was compromised in WT mice, whereas it was fully recovered in p40^-/- and p35^-/- mice. The mechanism of blood flow recovery involves an increase in capillary/arteriole density, endothelial nitric oxide synthase/Akt/vascular endothelial growth factor receptor 2 signaling, and a reduction in oxidative stress and inflammation. The disruption of IL-12 promotes angiogenesis and increases blood flow recovery in obese type 2 diabetic mice by an endothelial nitric oxide synthase/Akt/vascular endothelial growth factor receptor 2/oxidative stress-inflammation-dependent mechanism.

Early immune responses are independent of RGC dysfunction in glaucoma with complement component C3 being protective

Various immune response pathways are altered during early, predegenerative stages of glaucoma; however, whether the early immune responses occur secondarily to or independently of neuronal dysfunction is unclear. To investigate this relationship, we used the Wlds allele, which protects from axon dysfunction. We demonstrate that DBA/2J.Wlds mice develop high intraocular pressure (IOP) but are protected from retinal ganglion cell (RGC) dysfunction and neuroglial changes that otherwise occur early in DBA/2J glaucoma. Despite this, immune pathways are still altered in DBA/2J.Wlds mice. This suggests that immune changes are not secondary to RGC dysfunction or altered neuroglial interactions, but may be directly induced by the increased strain imposed by high IOP. One early immune response following IOP elevation is up-regulation of complement C3 in astrocytes of DBA/2J and DBA/2J.Wlds mice. Unexpectedly, because the disruption of other complement components, such as C1Q, is protective in glaucoma, C3 deficiency significantly increased the number of DBA/2J eyes with nerve damage and RGC loss at an early time point after IOP elevation. Transcriptional profiling of C3-deficient cultured astrocytes implicated EGFR signaling as a hub in C3-dependent responses. Treatment with AG1478, an EGFR inhibitor, also significantly increased the number of DBA/2J eyes with glaucoma at the same early time point. These findings suggest that C3 protects from early glaucomatous damage, a process that may involve EGFR signaling and other immune responses in the optic nerve head. Therefore, therapies that target specific components of the complement cascade, rather than global inhibition, may be more applicable for treating human glaucoma.

Novel EGFR inhibitors attenuate cardiac hypertrophy induced by angiotensin II

Cardiac hypertrophy is an important risk factor for heart failure. Epidermal growth factor receptor (EGFR) has been found to play a role in the pathogenesis of various cardiovascular diseases. The aim of this current study was to examine the role of EGFR in angiotensin II (Ang II)-induced cardiac hypertrophy and identify the underlying molecular mechanisms. In this study, we observed that both Ang II and EGF could increase the phospohorylation of EGFR and protein kinase B (AKT)/extracellular signal-regulated kinase (ERK), and then induce cell hypertrophy in H9c2 cells. Both pharmacological inhibitors and genetic silencing significantly reduced Ang II-induced EGFR signalling pathway activation, hypertrophic marker overexpression, and cell hypertrophy. In addition, our results showed that Ang II-induced EGFR activation is mediated by c-Src phosphorylation. In vivo, Ang II treatment significantly led to cardiac remodelling including cardiac hypertrophy, disorganization and fibrosis, accompanied by the activation of EGFR signalling pathway in the heart tissues, while all these molecular and pathological alterations were attenuated by the oral administration with EGFR inhibitors. In conclusion, the c-Src-dependent EGFR activation may play an important role in Ang II-induced cardiac hypertrophy, and inhibition of EGFR by specific molecules may be an effective strategy for the treatment of Ang II-associated cardiac diseases.

Augmented EGF receptor tyrosine kinase activity impairs vascular function by NADPH oxidase-dependent mechanism in type 2 diabetic mouse

We previously determined that augmented EGFR tyrosine kinase (EGFRtk) impairs vascular function in type 2 diabetic mouse (TD2). Here we determined that EGFRtk causes vascular dysfunction through NADPH oxidase activity in TD2. Mesenteric resistance arteries (MRA) from C57/BL6 and db-/db- mice were mounted in a wired myograph and pre-incubated for 1h with either EGFRtk inhibitor (AG1478) or exogenous EGF. The inhibition of EGFRtk did not affect the contractile response to phenylephrine-(PE) and thromboxane-(U46619) or endothelium-dependent relaxation (EDR) to acetylcholine in MRA from control group. However, in TD2 mice, AG1478 reduced the contractile response to U46619, improved vasodilatation and reduced p22phox-NADPH expression, but had no effect on the contractile response to PE. The incubation of MRA with exogenous EGF potentiated the contractile response to PE in MRA from control and diabetic mice. However, EGF impaired the EDR and potentiated the vasoconstriction to U46619 only in the control group. Interestingly, NADPH oxidase inhibition in the presence of EGF restored the normal contraction to PE and improved the EDR but had no effect on the potentiated contraction to U46619. Vascular function improvement was associated with the rescue of eNOS and Akt and reduction in phosphorylated Rho-kinase, NOX4 mRNA levels, and NADPH oxidase activity. MRA from p47phox-/- mice incubated with EGF potentiated the contraction to U46619 but had no effect to PE or ACh responses. The present study provides evidence that augmented EGFRtk impairs vascular function by NADPH oxidase-dependent mechanism. Therefore, EGFRtk and oxidative stress should be potential targets to treat vascular dysfunction in TD2.

Myoblast-conditioned media improve regeneration and revascularization of ischemic muscles in diabetic mice

Introduction

Diabetes is associated with reduced expression of heme oxygenase-1 (HO-1), a heme-degrading enzyme with cytoprotective and proangiogenic properties. In myoblasts and muscle satellite cells HO-1 improves survival, proliferation and production of proangiogenic growth factors. Induction of HO-1 in injured tissues facilitates neovascularization, the process impaired in diabetes. We aimed to examine whether conditioned media from the HO-1 overexpressing myoblast cell line can improve a blood-flow recovery in ischemic muscles of diabetic mice.

Methods

Analysis of myogenic markers was performed at the mRNA level in primary muscle satellite cells, isolated by a pre-plate technique from diabetic db/db and normoglycemic wild-type mice, and then cultured under growth or differentiation conditions. Hind limb ischemia was performed by femoral artery ligation in db/db mice and blood recovery was monitored by laser Doppler measurements. Mice were treated with a single intramuscular injection of conditioned media harvested from wild-type C2C12 myoblast cell line, C2C12 cells stably transduced with HO-1 cDNA, or with unconditioned media.

Results

Expression of HO-1 was lower in muscle satellite cells isolated from muscles of diabetic db/db mice when compared to their wild-type counterparts, what was accompanied by increased levels of Myf5 or CXCR4, and decreased Mef2 or Pax7. Such cells also displayed diminished differentiation potential when cultured in vitro, as shown by less effective formation of myotubes and reduced expression of myogenic markers (myogenic differentiation antigen - myoD, myogenin and myosin). Blood flow recovery after induction of severe hind limb ischemia was delayed in db/db mice compared to that in normoglycemic individuals. To improve muscle regeneration after ischemia, conditioned media collected from differentiating C2C12 cells (control and HO-1 overexpressing) were injected into hind limbs of diabetic mice. Analysis of blood flow revealed that media from HO-1 overexpressing cells accelerated blood-flow recovery, while immunohistochemical staining assessment of vessel density in injected muscle confirmed increased angiogenesis. The effect might be mediated by stromal-cell derived factor-1α proangiogenic factor, as its secretion is elevated in HO-1 overexpressing cells.

Conclusions

In conclusion, paracrine stimulation of angiogenesis in ischemic skeletal muscle using conditioned media may be a safe approach exploiting protective and proangiogenic properties of HO-1 in diabetes.

Nuclear factor kappa B inhibition improves conductance artery function in type 2 diabetic mice

BACKGROUND

We previously reported that enhanced nuclear factor kappa B (NFκB) activity is responsible for resistance arteries dysfunction in type 2 diabetic mice.

METHODS

In this study, we aimed to determine whether augmented NFκB activity also impairs conductance artery (thoracic aorta) function in type 2 diabetic mice. We treated type 2 diabetic (db(-) /db(-) ) and control (db(-) /db(+) ) mice with two NFκB inhibitors (dehydroxymethylepoxyquinomicin, 6 mg/kg, twice a week and IKK-NBD peptide, 500 µg/kg/day) for 4 weeks.

RESULTS

As expected, the NFκB inhibition did not affect blood glucose level and body weight. Thoracic aorta vascular endothelium-dependent relaxation (EDR), determined by the wire myograph, was impaired in diabetic mice compared with control and was significantly improved after NFκB inhibition. Interestingly, thoracic EDR was also rescued in db(-) /db(-p50NFκB-/-) and db(-) /db(-PARP-1-/-) double knockout mice compared with db(-) /db(-) mice. Similarly, the acute in vitro down regulation of NFκB-p65 using p65 shRNA lentiviral particles in arteries from db(-) /db(-) mice also improved thoracic aorta EDR. Western blot analysis showed that the p65NFκB phosphorylation, cleaved PARP-1 and COX-2 expression were increased in thoracic aorta from diabetic mice, which were restored after NFκB inhibition and in db(-) /db(-p-50NFκB-/-) and db(-) /db(-PARP-1-/-) mice.

CONCLUSIONS

The present results indicate that in male type 2 diabetic mice, the augmented NFκB activity also impairs conductance artery function through PARP-1 and COX-2-dependent mechanisms.

Role of epidermal growth factor receptor in vascular structure and function

PURPOSE OF THE REVIEW

The epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase with a wide implication in tumor biology, wound healing and development. Besides acting as a growth factor receptor activated by ligands such as EGF, the EGFR can also be transactivated and thereby mediate cross-talk with different signaling pathways. The aim of this review is to illustrate the Janus-faced function of the EGFR in the vasculature with its relevance for vascular biology and disease.

RECENT FINDINGS

Over recent years, the number of identified signaling partners of the EGFR has steadily increased, as have the biological processes in which the EGFR is thought to be involved. Recently, new models have allowed investigation of EGFR effects in vivo, shedding some light on the overall function of the EGFR in the vasculature. At the same time, EGFR inhibitors and antibodies have become increasingly established in cancer therapy, providing potential therapeutic tools for decreasing EGFR signaling.

SUMMARY

The EGFR is a versatile signaling pathway integrator associated with vascular homeostasis and disease. In addition to modulating basal vascular tone and tissue homeostasis, the EGFR also seems to be involved in proinflammatory, proliferative, migratory and remodeling processes, with enhanced deposition of extracellular matrix components, thereby promoting vascular diseases such as hypertension or atherosclerosis.

BDNF-ERK-CREB signalling mediates the role of miR-132 in the regulation of the effects of oleanolic acid in male mice

BACKGROUND

Although previous study has demonstrated that brain-derived neurotrophic factor (BDNF) is involved in the antidepressant-like effect of oleanolic acid, there is little information regarding the details of the molecular mechanism involved in this effect.

METHODS

We used a chronic unpredictable mild stress (CUMS) model to test the antidepressant-like effect of oleanolic acid on depressant-like behaviour, miR-132 expression and synaptic protein expression in the male mouse hippocampus. Furthermore, we explored the possible signalling pathways associated with miR-132 expression that mediate the effect of oleanolic acid on neuronal proliferation.

RESULTS

The results demonstrated that a 3-week treatment with oleanolic acid ameliorated CUMS-induced anhedonic and anxiogenic behaviours. Furthermore, we found that oleanolic acid led to the BDNF-related phosphorylation and activation of extracellular signal-regulated kinases (ERK) and cyclic adenosine monophosphate response element binding protein (CREB), which was associated with the upregulation of miR-132 and hippocampal neuronal proliferation. Moreover, experiments with an miR-132 antagomir revealed that targeting miR-132 led to inhibition of neuronal proliferation and the postsynaptic density protein 95, but did not affect presynaptic protein synapsin I.

LIMITATIONS

Several other stimuli can also induce CREB phosphorylation in the hippocampus. Thus, regulation of miR-132 may not be restricted to neurotrophic signalling.

CONCLUSION

Our results show that oleanolic acid induces the upregulation of miR-132, which serves as an important regulator of neurotrophic actions, mainly through the activation of the hippocampal BDNF-ERK-CREB signalling pathways.

Vasodilator responses to acetylcholine are not mediated by the activation of soluble guanylate cyclase or TRPV4 channels in the rat

The effects of 1H-[1,2,4]-oxadizaolo[4,3-]quinoxaline-1-one (ODQ), an inhibitor of the activation of soluble guanylate cyclase (sGC) on responses to NO donors acetylcholine (ACh) and bradykinin (BK) were investigated in the pulmonary and systemic vascular beds of the rat. In these studies the administration of ODQ in a dose of 5 mg/kg iv attenuated vasodilator responses to five different NO donors without inhibiting responses to ACh and BK in the systemic and pulmonary vascular beds of the rat. Vasodilator responses to ACh were not inhibited by l-NAME or the transient receptor vanilloid type 4 (TRPV4) antagonist GSK-2193874, which attenuated vasodilator responses to the TRPV4 agonist GSK-1016790A. ODQ did not inhibit vasodilator responses to agents reported to act in an NO-independent manner or to vasoconstrictor agents, and ODQ did not increase blood methemoglobin levels, suggesting that off target effects were minimal. These results show that ODQ in a dose that inhibited NO donor-mediated responses did not alter vasodilator responses to ACh in the pulmonary and systemic vascular beds and did not alter systemic vasodilator responses to BK. The present results indicate that decreases in pulmonary and systemic arterial pressures in response to ACh are not mediated by the activation of sGC or TRPV4 channels and that ODQ can be used to study the role of the activation of sGC in mediating vasodilator responses in the rat.

Enhanced p22phox expression impairs vascular function through p38 and ERK1/2 MAP kinase-dependent mechanisms in type 2 diabetic mice

Type 2 diabetes is associated with vascular complication. We hypothesized that increased nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunit p22(phox) expression impairs vascular endothelium-dependent relaxation (EDR) in type 2 diabetes. Type 2 diabetic (db(-)/db(-)) and control (db(-)/db(+)) mice were treated with reactive oxygen species (ROS) scavenger, polyethylene glycol superoxide dismutase (1,000 U/kg daily ip), or small interfering RNA p22(phox) (p22(phox)-lentivirus-small interfering RNA, 100 μg iv, 2 times/wk) for 1 mo. EDR was impaired in microvascular bed (coronary arteriole and femoral and mesenteric resistance arteries) from diabetic mice compared with control. Interestingly, ROS scavenger and p22(phox) downregulation did not affect blood glucose level or body weight but significantly improved EDR. Mitogen-activated protein kinases (ERK1/2 and p38) phosphorylation and NADPH oxidase activity were increased in arteries from diabetic mice and were reduced after ROS scavenger or p22(phox) downregulation in db(-)/db(-) mice. The present study showed that enhanced p22(phox) expression causes vascular dysfunction through ERK1/2 and p38-mitogen-activated protein kinase-dependent mechanisms in male type 2 diabetic mice. Therefore, p22(phox) could be an important target to improve vascular function in diabetes.

Enhanced NF-κB activity impairs vascular function through PARP-1-, SP-1-, and COX-2-dependent mechanisms in type 2 diabetes

Type 2 diabetes (T2D) is associated with vascular dysfunction. We hypothesized that increased nuclear factor-κB (NF-κB) signaling contributes to vascular dysfunction in T2D. We treated type 2 diabetic (db(-)/db(-)) and control (db(-)/db(+)) mice with two NF-κB inhibitors (6 mg/kg dehydroxymethylepoxyquinomicin twice a week and 500 μg/kg/day IKK-NBD peptide) for 4 weeks. Pressure-induced myogenic tone was significantly potentiated, while endothelium-dependent relaxation (EDR) was impaired in small coronary arterioles and mesenteric resistance artery from diabetic mice compared with controls. Interestingly, diabetic mice treated with NF-κB inhibitors had significantly reduced myogenic tone potentiation and improved EDR. Importantly, vascular function was also rescued in db(-)/db(-p50NF-κB-/-) and db(-)/db(-PARP-1-/-) double knockout mice compared with db(-)/db(-) mice. Additionally, the acute in vitro downregulation of NF-κB-p65 using p65NF-κB short hairpin RNA lentivirus in arteries from db(-)/db(-) mice also improved vascular function. The NF-κB inhibition did not affect blood glucose level or body weight. The RNA levels for Sp-1 and eNOS phosphorylation were decreased, while p65NF-κB phosphorylation, cleaved poly(ADP-ribose) polymerase (PARP)-1, and cyclooxygenase (COX)-2 expression were increased in arteries from diabetic mice, which were restored after NF-κB inhibition and in db(-)/db(-p50NF-κB-/-) and db(-)/db(-PARP-1-/-) mice. In the current study, we provided evidence that enhanced NF-κB activity impairs vascular function by PARP-1-, Sp-1-, and COX-2-dependent mechanisms in male type 2 diabetic mice. Therefore, NF-κB could be a potential target to overcome diabetes-induced vascular dysfunction.