The role of p66Shc deletion in age-associated arterial dysfunction and disease states

Aging-Induced Impairment of Vascular Function: Mitochondrial Redox Contributions and Physiological/Clinical Implications

Significance: The vasculature responds to the respiratory needs of tissue by modulating luminal diameter through smooth muscle constriction or relaxation. Coronary perfusion, diastolic function, and coronary flow reserve are drastically reduced with aging. This loss of blood flow contributes to and exacerbates pathological processes such as angina pectoris, atherosclerosis, and coronary artery and microvascular disease. Recent Advances: Increased attention has recently been given to defining mechanisms behind aging-mediated loss of vascular function and development of therapeutic strategies to restore youthful vascular responsiveness. The ultimate goal aims at providing new avenues for symptom management, reversal of tissue damage, and preventing or delaying of aging-induced vascular damage and dysfunction in the first place. Critical Issues: Our major objective is to describe how aging-associated mitochondrial dysfunction contributes to endothelial and smooth muscle dysfunction via dysregulated reactive oxygen species production, the clinical impact of this phenomenon, and to discuss emerging therapeutic strategies. Pathological changes in regulation of mitochondrial oxidative and nitrosative balance (Section 1) and mitochondrial dynamics of fission/fusion (Section 2) have widespread effects on the mechanisms underlying the ability of the vasculature to relax, leading to hyperconstriction with aging. We will focus on flow-mediated dilation, endothelial hyperpolarizing factors (Sections 3 and 4), and adrenergic receptors (Section 5), as outlined in Figure 1. The clinical implications of these changes on major adverse cardiac events and mortality are described (Section 6). Future Directions: We discuss antioxidative therapeutic strategies currently in development to restore mitochondrial redox homeostasis and subsequently vascular function and evaluate their potential clinical impact (Section 7). Antioxid. Redox Signal. 35, 974-1015.

Sleep, brain vascular health and ageing

Sleep maintains the function of the entire body through homeostasis. Chronic sleep deprivation (CSD) is a prime health concern in the modern world. Previous reports have shown that CSD has profound negative effects on brain vasculature at both the cellular and molecular levels, and that this is a major cause of cognitive dysfunction and early vascular ageing. However, correlations among sleep deprivation (SD), brain vascular changes and ageing have barely been looked into. This review attempts to correlate the alterations in the levels of major neurotransmitters (acetylcholine, adrenaline, GABA and glutamate) and signalling molecules (Sirt1, PGC1α, FOXO, P66^shc, PARP1) in SD and changes in brain vasculature, cognitive dysfunction and early ageing. It also aims to connect SD-induced loss in the number of dendritic spines and their effects on alterations in synaptic plasticity, cognitive disabilities and early vascular ageing based on data available in scientific literature. To the best of our knowledge, this is the first article providing a pathophysiological basis to link SD to brain vascular ageing.

Vascular ageing in hypertension: Focus on mitochondria

Hypertension is a common age-related disease, along with vascular and neurodegenerative diseases. Vascular ageing increases during hypertension, but hypertension itself accelerates vascular ageing, thus creating a vicious circle. Vascular stiffening, endothelial dysfunction, impaired contractility and vasorelaxation are the main alterations related to vascular ageing, as a consequence of vascular smooth muscle and endothelial cells senescence. Several molecular mechanisms have been involved into the functional and morphological changes of the aged vessels. Among them, oxidative stress, inflammation, extracellular matrix deregulation and mitochondrial dysfunction are the best characterized. In the present review, we discuss relevant literature about the biology of vascular and cerebrovascular ageing with a particular focus on mitochondria signalling. We underline the therapeutic strategies, able to improve mitochondrial health, which may represent a promising tool to decrease vascular dysfunction associated with ageing and hypertension-related complications.

Endothelin receptor A and p66Shc regulate spontaneous Ca2+ oscillations in smooth muscle cells controlling renal arterial spontaneous motion

Adaptor protein p66Shc is overexpressed in smooth muscle cells of renal resistance vessels of hypertensive salt-sensitive rats and is involved in the regulation of renal vascular tone. We applied 2-photon laser scanning fluorescence microscopy to analyze spontaneous dynamic fluctuations in intracellular calcium concentrations ([Ca²⁺]_i) in smooth muscle cells embedded in the walls of freshly isolated renal resistance arteries. The amplitude, number of events, and frequency of spontaneous [Ca²⁺]_i oscillations triggered by endogenously released endothelin-1 were recorded in smooth muscle cells of the renal arteries. Endothelin receptor A antagonist BQ123 dramatically reduced the amplitude and frequency of spontaneous Ca²⁺ events, producing marked inhibition of renal vessels spontaneous motion. Spontaneous Ca²⁺ fluctuations in smooth muscle cells of p66Shc knockout (p66ShcKO) rats had significantly higher amplitude than in control rats. The frequency of spontaneous [Ca²⁺]_i oscillations did not change in p66ShcKO rats, suggesting that p66Shc expression did not affect endothelin-1 release from resident endothelial cells. Acute application of endothelin-1 revealed significantly elevated production of the total [Ca²⁺]_i in p66ShcKO rats. Spontaneous cytosolic Ca²⁺ oscillations in smooth muscle cells of renal vessels mediate their spontaneous motion via the endothelin-1/endothelin receptor A pathway. p66Shc decreases the amplitude of individual changes in [Ca²⁺]_i, which mitigates the spontaneous motion of renal vessels.-Palygin, O., Miller, B. S., Nishijima, Y., Zhang, D. X., Staruschenko, A., Sorokin, A. Endothelin receptor A and p66Shc regulate spontaneous Ca²⁺ oscillations in smooth muscle cells controlling renal arterial spontaneous motion.

Epigenetics and Immunometabolism in Diabetes and Aging

SIGNIFICANCE

A strong relationship between hyperglycemia, impaired insulin pathway, and cardiovascular disease in type 2 diabetes (T2D) is linked to oxidative stress and inflammation. Immunometabolic pathways link these pathogenic processes and pose important potential therapeutic targets. Recent Advances: The link between immunity and metabolism is bidirectional and includes the role of inflammation in the pathogenesis of metabolic disorders such as T2D, obesity, metabolic syndrome, and hypertension and the role of metabolic factors in regulation of immune cell functions. Low-grade inflammation, oxidative stress, balance between superoxide and nitric oxide, and the infiltration of macrophages, T cells, and B cells in insulin-sensitive tissues lead to metabolic impairment and accelerated aging.

CRITICAL ISSUES

Inflammatory infiltrate and altered immune cell phenotype precede development of metabolic disorders. Inflammatory changes are tightly linked to alterations in metabolic status and energy expenditure and are controlled by epigenetic mechanisms.

FUTURE DIRECTIONS

A better comprehension of these mechanistic insights is of utmost importance to identify novel molecular targets. In this study, we describe a complex scenario of epigenetic changes and immunometabolism linking to diabetes and aging-associated vascular disease. Antioxid. Redox Signal. 29, 257-274.

SIRT1 and SIRT6 Signaling Pathways in Cardiovascular Disease Protection

SIGNIFICANCE

Oxidative stress represents the common hallmark of pathological conditions associated with cardiovascular disease (CVD), including atherosclerosis, heart failure, hypertension, aging, diabetes, and other vascular system-related diseases. The sirtuin (SIRT) family, comprising seven proteins (SIRT1-SIRT7) sharing a highly conserved nicotinamide adenine dinucleotide (NAD+)-binding catalytic domain, attracted a great attention for the past few years as stress adaptor and epigenetic enzymes involved in the cellular events controlling aging-related disorder, cancer, and CVD. Recent Advances: Among sirtuins, SIRT1 and SIRT6 are the best characterized for their protective roles against inflammation, vascular aging, heart disease, and atherosclerotic plaque development. This latest role has been only recently unveiled for SIRT6. Of interest, in recent years, complex signaling networks controlled by SIRT1 and SIRT6 common to stress resistance, vascular aging, and CVD have emerged.

CRITICAL ISSUES

We provide a comprehensive overview of recent developments on the molecular signaling pathways controlled by SIRT1 and SIRT6, two post-translational modifiers proven to be valuable tools to dampen inflammation and oxidative stress at the cardiovascular level.

FUTURE DIRECTIONS

A deeper understanding of the epigenetic mechanisms through which SIRT1 and SIRT6 act in the signalings responsible for onset and development CVD is a prime scientific endeavor of the upcoming years. Multiple "omic" technologies will have widespread implications in understanding such mechanisms, speeding up the achievement of selective and efficient pharmacological modulation of sirtuins for future applications in the prevention and treatment of CVD. Antioxid. Redox Signal. 28, 711-732.

European contribution to the study of ROS: A summary of the findings and prospects for the future from the COST action BM1203 (EU-ROS)

The European Cooperation in Science and Technology (COST) provides an ideal framework to establish multi-disciplinary research networks. COST Action BM1203 (EU-ROS) represents a consortium of researchers from different disciplines who are dedicated to providing new insights and tools for better understanding redox biology and medicine and, in the long run, to finding new therapeutic strategies to target dysregulated redox processes in various diseases. This report highlights the major achievements of EU-ROS as well as research updates and new perspectives arising from its members. The EU-ROS consortium comprised more than 140 active members who worked together for four years on the topics briefly described below. The formation of reactive oxygen and nitrogen species (RONS) is an established hallmark of our aerobic environment and metabolism but RONS also act as messengers via redox regulation of essential cellular processes. The fact that many diseases have been found to be associated with oxidative stress established the theory of oxidative stress as a trigger of diseases that can be corrected by antioxidant therapy. However, while experimental studies support this thesis, clinical studies still generate controversial results, due to complex pathophysiology of oxidative stress in humans. For future improvement of antioxidant therapy and better understanding of redox-associated disease progression detailed knowledge on the sources and targets of RONS formation and discrimination of their detrimental or beneficial roles is required. In order to advance this important area of biology and medicine, highly synergistic approaches combining a variety of diverse and contrasting disciplines are needed.

Insights into the Shc Family of Adaptor Proteins

The Shc family of adaptor proteins is a group of proteins that lacks intrinsic enzymatic activity. Instead, Shc proteins possess various domains that allow them to recruit different signalling molecules. Shc proteins help to transduce an extracellular signal into an intracellular signal, which is then translated into a biological response. The Shc family of adaptor proteins share the same structural topography, CH2-PTB-CH1-SH2, which is more than an isoform of Shc family proteins; this structure, which includes multiple domains, allows for the posttranslational modification of Shc proteins and increases the functional diversity of Shc proteins. The deregulation of Shc proteins has been linked to different disease conditions, including cancer and Alzheimer’s, which indicates their key roles in cellular functions. Accordingly, a question might arise as to whether Shc proteins could be targeted therapeutically to correct their disturbance. To answer this question, thorough knowledge must be acquired; herein, we aim to shed light on the Shc family of adaptor proteins to understand their intracellular role in normal and disease states, which later might be applied to connote mechanisms to reverse the disease state.

Skeletal muscle insulin resistance: role of mitochondria and other ROS sources

At present, obesity is one of the most important public health problems in the world because it causes several diseases and reduces life expectancy. Although it is well known that insulin resistance plays a pivotal role in the development of type 2 diabetes mellitus (the more frequent disease in obese people) the link between obesity and insulin resistance is yet a matter of debate. One of the most deleterious effects of obesity is the deposition of lipids in non-adipose tissues when the capacity of adipose tissue is overwhelmed. During the last decade, reduced mitochondrial function has been considered as an important contributor to 'toxic' lipid metabolite accumulation and consequent insulin resistance. More recent reports suggest that mitochondrial dysfunction is not an early event in the development of insulin resistance, but rather a complication of the hyperlipidemia-induced reactive oxygen species (ROS) production in skeletal muscle, which might promote mitochondrial alterations, lipid accumulation and inhibition of insulin action. Here, we review the literature dealing with the mitochondria-centered mechanisms proposed to explain the onset of obesity-linked IR in skeletal muscle. We conclude that the different pathways leading to insulin resistance may act synergistically because ROS production by mitochondria and other sources can result in mitochondrial dysfunction, which in turn can further increase ROS production leading to the establishment of a harmful positive feedback loop.

Central Role of Metabolism in Endothelial Cell Function and Vascular Disease

The importance of endothelial cell (EC) metabolism and its regulatory role in the angiogenic behavior of ECs during vessel formation and in the function of different EC subtypes determined by different vascular beds has been recognized only in the last few years. Even more importantly, apart from a role of nitric oxide and reactive oxygen species in EC dysfunction, deregulations of EC metabolism in disease only recently received increasing attention. Although comprehensive metabolic characterization of ECs still needs further investigation, the concept of targeting EC metabolism to treat vascular disease is emerging. In this overview, we summarize EC-specific metabolic pathways, describe the current knowledge on their deregulation in vascular diseases, and give an outlook on how vascular endothelial metabolism can serve as a target to normalize deregulated endothelium.

Immune enhancement effects and extraction optimization of polysaccharides from Citrus aurantium L. var. amara Engl

The crude polysaccharides ofCitrus aurantiumL. var.amaraEngl (CAVAPs) were extracted and their bioactivities including DPPH radical scavenging activity, cytotoxicity to human breast cancer cells, MCF-7, as well as lung cancer cells, HCC827, and their immune-enhancement activity were evaluated.

Recombinant adenovirus of human p66Shc inhibits MCF-7 cell proliferation

The aim of this work was to construct a human recombinant p66Shc adenovirus and to investigate the inhibition of recombinant p66Shc adenovirus on MCF-7 cells. The recombinant adenovirus expression vector was constructed using the Adeno-X Adenoviral System 3. Inhibition of MCF-7 cell proliferation was determined by MTT. Intracellular ROS was measured by DCFH-DA fluorescent probes, and 8-OHdG was detected by ELISA. Cell apoptosis and the cell cycle were assayed by flow cytometry. Western blot were used to observe protein expression. p66Shc expression was upregulated in 4 cell lines after infection. The inhibitory effect of p66Shc recombinant adenovirus on MCF-7 cells was accompanied by enhanced ROS and 8-OHdG. However, no significant differences were observed in the cell apoptosis rate. The ratio of the cell cycle G2/M phase showed a significant increase. Follow-up experiments demonstrated that the expressions of p53, p-p53, cyclin B1 and CDK1 were upregulated with the overexpression of p66Shc. The Adeno-X Adenoviral System 3 can be used to efficiently construct recombinant adenovirus containing p66Shc gene, and the Adeno-X can inhibit the proliferation of MCF-7 cells by inducing cell cycle arrest at the G2/M phase. These results suggested that p66Shc may be a key target for clinical cancer therapy.

Ageing, metabolism and cardiovascular disease

Age is one of the major risk factors associated with cardiovascular disease (CVD). About one-fifth of the world population will be aged 65 or older by 2030, with an exponential increase in CVD prevalence. It is well established that environmental factors (overnutrition, smoking, pollution, sedentary lifestyles) may lead to premature defects in mitochondrial functionality, insulin signalling, endothelial homeostasis and redox balance, fostering early senescent features. Over the last few years, molecular investigations have unveiled common signalling networks which may link the ageing process with deterioration of cardiovascular homeostasis and metabolic disturbances, namely insulin resistance. These different processes seem to be highly interconnected and their interplay may favour adverse vascular and cardiac phenotypes responsible for myocardial infarction, stroke and heart failure. In the present review, we carefully describe novel molecular cues underpinning ageing, metabolism and CVD. In particular, we describe a dynamic interplay between emerging pathways such as FOXOs, AMPK, SIRT1, p66(Shc) , JunD and NF-kB. This overview will provide the background for attractive molecular targets to prevent age-driven pathology in the vasculature and the heart.

Resistance exercise training increase activation of AKT-eNOS and Ref-1 expression by FOXO-1 activation in aorta of F344 rats

PURPOSE

This study investigated the effects of resistance exercise on the Akt-eNOS, the activation of antioxidant protein and FOXO1 in the aorta of F344 rats.

METHODS

Male 7 week-old F344 rats were randomly divided into 2 groups: a climbing group (n = 6) and a sedentary group (n = 6). H&E staining and western blotting were used to analyze the rat aortas and target proteins.

RESULTS

Resistance exercise training did not significantly affect aortic structure. Phosphorylation of AKT and eNOS and expression of MnSOD and Ref-1 were significantly increased while FOXO1 phosphorylation was significantly decreased in the resistance exercise group compared with the sedentary group.

CONCLUSION

We demonstrate that resistance exercise activates the Akt-eNOS and Ref-1 protein without changes to aortic thickness via FOXO-1 activation in the aorta of F344 rats.

Mitochondrial Oxidative Stress, Mitochondrial DNA Damage and Their Role in Age-Related Vascular Dysfunction

The prevalence of cardiovascular diseases is significantly increased in the older population. Risk factors and predictors of future cardiovascular events such as hypertension, atherosclerosis, or diabetes are observed with higher frequency in elderly individuals. A major determinant of vascular aging is endothelial dysfunction, characterized by impaired endothelium-dependent signaling processes. Increased production of reactive oxygen species (ROS) leads to oxidative stress, loss of nitric oxide (^•NO) signaling, loss of endothelial barrier function and infiltration of leukocytes to the vascular wall, explaining the low-grade inflammation characteristic for the aged vasculature. We here discuss the importance of different sources of ROS for vascular aging and their contribution to the increased cardiovascular risk in the elderly population with special emphasis on mitochondrial ROS formation and oxidative damage of mitochondrial DNA. Also the interaction (crosstalk) of mitochondria with nicotinamide adenosine dinucleotide phosphate (NADPH) oxidases is highlighted. Current concepts of vascular aging, consequences for the development of cardiovascular events and the particular role of ROS are evaluated on the basis of cell culture experiments, animal studies and clinical trials. Present data point to a more important role of oxidative stress for the maximal healthspan (healthy aging) than for the maximal lifespan.

Genetic deletion of the adaptor protein p66Shc increases susceptibility to short-term ischaemic myocardial injury via intracellular salvage pathways

AIMS

Several intracellular mediators have been implicated as new therapeutic targets against myocardial ischaemia and reperfusion injury. However, clinically effective salvage pathways remain undiscovered. Here, we focused on the potential role of the adaptor protein p66(Shc) as a regulator of myocardial injury in a mouse model of cardiac ischaemia and reperfusion.

METHODS AND RESULTS

Adult male p66(Shc) deficient (p66(Shc) (-/-)) and C57Bl/6 wild-type (WT) mice were exposed to 30, 45, or 60 min of ischaemia and reperfusion (5, 15 min, or 24 h). Infarct size, systemic and intracardiac inflammation and oxidants, as well as cytosolic and mitochondrial apoptotic pathways were investigated. Following 30, but not 45 or 60 min of ischaemia, genetic p66(Shc) deficiency was associated with larger infarcts. In WT mice, in vivo p66(Shc) knock down by siRNA with transient protein deficiency confirmed these findings. P66(Shc) inhibition was not associated with any modification in post-infarction inflammation, oxidative burst nor cardiac vessel density or structure. However, in p66(Shc) (-/-) mice activation of the protective and anti-apoptotic Reperfusion Injury Salvage Kinases and Survivor Activating Factor Enhancement pathways were blunted and mitochondrial swelling and cellular apoptosis via the caspase-3 pathway increased compared with WT.

CONCLUSIONS

Genetic deletion of p66(Shc) increased susceptibility to myocardial injury in response to short-term ischaemia and reperfusion in mice. Still, additional studies are needed for assessing the role of this pathway in acute coronary syndrome patients.

Dual role of endothelial nitric oxide synthase in oxidized LDL-induced, p66Shc-mediated oxidative stress in cultured human endothelial cells

BACKGROUND

The aging gene p66Shc, is an important mediator of oxidative stress-induced vascular dysfunction and disease. In cultured human aortic endothelial cells (HAEC), p66Shc deletion increases endothelial nitric oxide synthase (eNOS) expression and nitric oxide (NO) bioavailability via protein kinase B. However, the putative role of the NO pathway on p66Shc activation remains unclear. This study was designed to elucidate the regulatory role of the eNOS/NO pathway on p66Shc activation.

METHODS AND RESULTS

Incubation of HAEC with oxidized low density lipoprotein (oxLDL) led to phosphorylation of p66Shc at Ser-36, resulting in an enhanced production of superoxide anion (O2-). In the absence of oxLDL, inhibition of eNOS by small interfering RNA or L-NAME, induced p66Shc phosphorylation, suggesting that basal NO production inhibits O2- production. oxLDL-induced, p66Shc-mediated O2- was prevented by eNOS inhibition, suggesting that when cells are stimulated with oxLDL eNOS is a source of reactive oxygen species. Endogenous or exogenous NO donors, prevented p66Shc activation and reduced O2- production. Treatment with tetrahydrobiopterin, an eNOS cofactor, restored eNOS uncoupling, prevented p66Shc activation, and reduced O2- generation. However, late treatment with tetrahydropterin did not yield the same result suggesting that eNOS uncoupling is the primary source of reactive oxygen species.

CONCLUSIONS

The present study reports that in primary cultured HAEC treated with oxLDL, p66Shc-mediated oxidative stress is derived from eNOS uncoupling. This finding contributes novel information on the mechanisms of p66Shc activation and its dual interaction with eNOS underscoring the importance eNOS uncoupling as a putative antioxidant therapeutical target in endothelial dysfunction as observed in cardiovascular disease.

CRIF1 deficiency induces p66shc-mediated oxidative stress and endothelial activation

Mitochondrial dysfunction has been implicated in the pathophysiology of various cardiovascular diseases. CRIF1 is a protein present in the mitochondria associated with large mitoribosomal subunits, and CRIF1 knockdown induces mitochondrial dysfunction and promotes ROS production. p66shc is a redox enzyme implicated in mitochondrial ROS generation and translation of oxidative signals and, therefore, is a key factor for oxidative stress in endothelial cells. In this study, we investigated whether mitochondrial dysfunction induced by CRIF1 knockdown induces p66shc stimulation and plays any role in mitochondrial dysfunction-induced endothelial activation. Knockdown of CRIF1 decreased the expression of mitochondrial oxidative phosphorylation (OXPHOS) complexes I, III and IV, leading to increased mitochondrial ROS (mtROS) and hyperpolarization of the mitochondrial membrane potential. Knockdown of CRIF1 also stimulated phosphorylation of p66shc and increased cytosolic ROS in endothelial cells. Furthermore, the expression of vascular cell adhesion molecule-1 and endoplasmic reticulum stress proteins were increased upon CRIF1 knockdown in endothelial cells. However, p66shc knockdown blunted the alteration in mitochondrial dynamics and ROS production in CRIF1 knockdown endothelial cells. In addition, p66shc knockdown reduced the CRIF1 knockdown-induced increases in adhesion between monocytes and endothelial cells. Taken together, these results suggest that CRIF1 knockdown partially induces endothelial activation via increased ROS production and phosphorylation of p66shc.

Oxidative stress and vascular inflammation in aging

Vascular aging, a determinant factor for cardiovascular disease and health status in the elderly, is now viewed as a modifiable risk factor. Impaired endothelial vasodilation is a early hallmark of arterial aging that precedes the clinical manifestations of vascular dysfunction, the first step to cardiovascular disease and influencing vascular outcomes in the elderly. Accordingly, the preservation of endothelial function is thought to be an essential determinant of healthy aging. With special attention on the effects of aging on the endothelial function, this review is focused on the two main mechanisms of aging-related endothelial dysfunction: oxidative stress and inflammation. Aging vasculature generates an excess of the reactive oxygen species (ROS), superoxide and hydrogen peroxide, that compromise the vasodilatory activity of nitric oxide (NO) and facilitate the formation of the deleterious radical, peroxynitrite. Main sources of ROS are mitochondrial respiratory chain and NADPH oxidases, although NOS uncoupling could also account for ROS generation. In addition, reduced antioxidant response mediated by erythroid-2-related factor-2 (Nrf2) and downregulation of mitochondrial manganese superoxide dismutase (SOD2) contributes to the establishment of chronic oxidative stress in aged vessels. This is accompanied by a chronic low-grade inflammatory phenotype that participates in defective endothelial vasodilation. The redox-sensitive transcription factor, nuclear factor-κB (NF-κB), is upregulated in vascular cells from old subjects and drives a proinflammatory shift that feedbacks oxidative stress. This chronic NF-κB activation is contributed by increased angiotensin-II signaling and downregulated sirtuins and precludes adequate cellular response to acute ROS generation. Interventions targeted to recover endogenous antioxidant capacity and cellular stress response rather than exogenous antioxidants could reverse oxidative stress-inflammation vicious cycle in vascular aging. Lifestyle attitudes such as caloric restriction and exercise training appear as effective ways to overcome defective antioxidant response and inflammation, favoring successful vascular aging and decreasing the risk for cardiovascular disease.

Angiotensin II, NADPH oxidase, and redox signaling in the vasculature

SIGNIFICANCE

Angiotensin II (Ang II) influences the function of many cell types and regulates many organ systems, in large part through redox-sensitive processes. In the vascular system, Ang II is a potent vasoconstrictor and also promotes inflammation, hypertrophy, and fibrosis, which are important in vascular damage and remodeling in cardiovascular diseases. The diverse actions of Ang II are mediated via Ang II type 1 and Ang II type 2 receptors, which couple to various signaling molecules, including NADPH oxidase (Nox), which generates reactive oxygen species (ROS). ROS are now recognized as signaling molecules, critically placed in pathways activated by Ang II. Mechanisms linking Nox and Ang II are complex and not fully understood.

RECENT ADVANCES

Ang II regulates vascular cell production of ROS through various recently characterized Noxs, including Nox1, Nox2, Nox4, and Nox5. Activation of these Noxs leads to ROS generation, which in turn influences many downstream signaling targets of Ang II, including MAP kinases, RhoA/Rho kinase, transcription factors, protein tyrosine phosphatases, and tyrosine kinases. Activation of these redox-sensitive pathways regulates vascular cell growth, inflammation, contraction, and senescence.

CRITICAL ISSUES

Although there is much evidence indicating a role for Nox/ROS in Ang II function, there is still a paucity of information on how Ang II exerts cell-specific effects through ROS and how Nox isoforms are differentially regulated by Ang II. Moreover, exact mechanisms whereby ROS induce oxidative modifications of signaling molecules mediating Ang II actions remain elusive.

FUTURE DIRECTIONS

Future research should elucidate these issues to better understand the significance of Ang II and ROS in vascular (patho) biology.

Role of mitochondrial dysfunction and altered autophagy in cardiovascular aging and disease: from mechanisms to therapeutics

Advanced age is associated with a disproportionate prevalence of cardiovascular disease (CVD). Intrinsic alterations in the heart and the vasculature occurring over the life course render the cardiovascular system more vulnerable to various stressors in late life, ultimately favoring the development of CVD. Several lines of evidence indicate mitochondrial dysfunction as a major contributor to cardiovascular senescence. Besides being less bioenergetically efficient, damaged mitochondria also produce increased amounts of reactive oxygen species, with detrimental structural and functional consequences for the cardiovascular system. The age-related accumulation of dysfunctional mitochondrial likely results from the combination of impaired clearance of damaged organelles by autophagy and inadequate replenishment of the cellular mitochondrial pool by mitochondriogenesis. In this review, we summarize the current knowledge about relevant mechanisms and consequences of age-related mitochondrial decay and alterations in mitochondrial quality control in the cardiovascular system. The involvement of mitochondrial dysfunction in the pathogenesis of cardiovascular conditions especially prevalent in late life and the emerging connections with neurodegeneration are also illustrated. Special emphasis is placed on recent discoveries on the role played by alterations in mitochondrial dynamics (fusion and fission), mitophagy, and their interconnections in the context of age-related CVD and endothelial dysfunction. Finally, we discuss pharmacological interventions targeting mitochondrial dysfunction to delay cardiovascular aging and manage CVD.

DNA methylation of the p66Shc promoter is decreased in placental tissue from women delivering intrauterine growth restricted neonates

OBJECTIVE

The adaptor protein p66Shc generates mitochondrial reactive oxygen species and translates oxidative signals into apoptosis. We aimed to analyze potential alterations in total methylation and in p66Shc activation in placental tissues from women delivering intrauterine growth restricted neonates (IUGR) versus appropriate for gestational age (AGA) and small for gestational age (SGA) neonates.

METHOD

DNA methylation of the p66Shc promoter and of long interspersed nuclear elements (LINE-1), as a marker for total methylation, was quantified by automatic pyrosequencing in 15 IUGR, 25 AGA and 15 SGA placentas. Placental gene expression of p66Shc was determined by TaqMan real-time polymerase chain reaction.

RESULTS

No significant difference was found for LINE-1 methylation between IUGR, AGA and SGA newborns. DNA methylation of the p66Shc promoter was significantly decreased in the IUGR compared with the AGA group (p < 0.0001) and the SGA group (p < 0.0001). However, analysis of placental p66Shc gene expression did not show a significant difference between the three groups.

CONCLUSION

It remains speculative if the decreased p66Shc promoter methylation might play a role in the pathophysiology of endothelial dysfunction and cardiovascular disease after IUGR.

Cross-talk between SIRT1 and p66Shc in vascular diseases

Accumulating evidence indicates that oxidative stress can occur through overproduction of reactive oxygen species (ROS) and/or reduced anti-oxidant potentials under pathophysiological conditions and plays an important role in the development of cardiovascular diseases (CVDs). Adapter protein p66Shc has the property to directly stimulate mitochondrial ROS generation by an oxidoreductase activity. A growing body of evidence implies that p66Shc plays a critical role in the pathophysiology of age-related vascular diseases. Silent mating type information regulator 2 homolog 1 (SIRT1), a nicotinamide adenine dinucleotide (NAD+)-dependent class III histone deacetylase (HDAC), has also been implicated in protection against vascular aging and age-related vascular diseases. Recently, we demonstrated that SIRT1 protects blood vessels from hyperglycemia-induced endothelial dysfunction through a novel mechanism involving the downregulation of p66Shc expression. In this review, we discuss the cross-talk between these two longevity genes as a mechanism of preventing vascular diseases by involving anti-oxidative stress responses and inhibiting endothelial senescence.

Endothelial nitric oxide synthase, vascular integrity and human exceptional longevity

Aging is the sum of the deleterious changes that occur as time goes by. It is the main risk factor for the development of cardiovascular disease, and aging of the vasculature is the event that most often impacts on the health of elderly people. The “free-radical theory of aging” was proposed to explain aging as a consequence of the accumulation of reactive oxygen species (ROS). However, recent findings contradict this theory, and it now seems that mechanisms mediating longevity act through induction of oxidative stress. In fact, calorie restriction − a powerful way of delaying aging − increases ROS accumulation due to stimulation of the basal metabolic rate; moreover, reports show that antioxidant therapy is detrimental to healthy aging. We also now know that genetic manipulation of the insulin-like-growth-factor-1/insulin signal (IIS) has a profound impact on the rate of aging and that the IIS is modulated by calorie restriction and physical exercise. The IIS regulates activation of nitric oxide synthase (eNOS), the activity of which is essential to improving lifespan through calorie restriction, as demonstrated by experiments on eNOS knockout mice. Indeed, eNOS has a key role in maintaining vascular integrity during aging by activating vasorelaxation and allowing migration and angiogenesis. In this review, we will overview current literature on these topics and we will try to convince the reader of the importance of vascular integrity and nitric oxide production in determining healthy aging.

Deletion of the ageing gene p66(Shc) reduces early stroke size following ischaemia/reperfusion brain injury

AIMS

Stroke is a leading cause of morbidity and mortality, and its incidence increases with age. Both in animals and in humans, oxidative stress appears to play an important role in ischaemic stroke, with or without reperfusion. The adaptor protein p66(Shc) is a key regulator of reactive oxygen species (ROS) production and a mediator of ischaemia/reperfusion damage in ex vivo hearts. Hence, we hypothesized that p66(Shc) may be involved in ischaemia/reperfusion brain damage. To this end, we investigated whether genetic deletion of p66(Shc) protects from ischaemia/reperfusion brain injury.

METHODS AND RESULTS

Transient middle cerebral artery occlusion (MCAO) was performed to induce ischaemia/reperfusion brain injury in wild-type (Wt) and p66(Shc) knockout mice (p66(Shc-/-)), followed by 24 h of reperfusion. Cerebral blood flow and blood pressure measurements revealed comparable haemodynamics in both experimental groups. Neuronal nuclear antigen immunohistochemical staining showed a significantly reduced stroke size in p66(Shc-/-) when compared with Wt mice (P < 0.05, n = 7-8). In line with this, p66(Shc-/-) mice exhibited a less impaired neurological function and a decreased production of free radicals locally and systemically (P < 0.05, n = 4-5). Following MCAO, protein levels of gp91phox nicotinamide adenine dinucleotide phosphate oxidase subunit were increased in brain homogenates of Wt (P < 0.05, n = 4), but not of p66(Shc-/-) mice. Further, reperfusion injury in Wt mice induced p66(Shc) protein in the basilar and middle cerebral artery, but not in brain tissue, suggesting a predominant involvement of vascular p66(Shc).

CONCLUSION

In the present study, we show that the deletion of the ageing gene p66(Shc) protects mice from ischaemia/reperfusion brain injury through a blunted production of free radicals. The ROS mediator p66(Shc) may represent a novel therapeutical target for the treatment of ischaemic stroke.

Chronic matrix metalloproteinase inhibition retards age-associated arterial proinflammation and increase in blood pressure

Age-associated arterial remodeling involves arterial wall collagen deposition and elastin fragmentation, as well as an increase in arterial pressure. This arterial remodeling is linked to proinflammatory signaling, including transforming growth factor-β1, monocyte chemoattractant protein 1, and proendothelin 1, activated by extracellular matrix metalloproteinases (MMPs) and orchestrated, in part, by the transcriptional factor ets-1. We tested the hypothesis that inhibition of MMP activation can decelerate the age-associated arterial proinflammation and its attendant increase in arterial pressure. Indeed, chronic administration of a broad-spectrum MMP inhibitor, PD166739, via a daily gavage, to 16-month-old rats for 8 months markedly blunted the expected age-associated increases in arterial pressure. This was accompanied by the following: (1) inhibition of the age-associated increases in aortic gelatinase and interstitial collagenase activity in situ; (2) preservation of the elastic fiber network integrity; (3) a reduction of collagen deposition; (4) a reduction of monocyte chemoattractant protein 1 and transforming growth factor-β1 activation; (5) a diminution in the activity of the profibrogenic signaling molecule SMAD-2/3 phosphorylation; (6) inhibition of proendothelin 1 activation; and (7) downregulation of expression of ets-1. Acute exposure of cultured vascular smooth muscle cells in vitro to proendothelin 1 increased both the transcription and translation of ets-1, and these effects were markedly reduced by MMP inhibition. Furthermore, infection of vascular smooth muscle cells with an adenovirus harboring a full-length ets-1 cDNA increased activities of both transforming growth factor-β1 and monocyte chemoattractant protein 1. Collectively, our results indicate that MMP inhibition retards age-associated arterial proinflammatory signaling, and this is accompanied by preservation of intact elastin fibers, a reduction in collagen, and blunting of an age-associated increase in blood pressure.

Microparticles induce cell cycle arrest through redox-sensitive processes in endothelial cells: implications in vascular senescence

BACKGROUND

Chronic disease accelerates endothelial dysfunction in aging, a process associated with cell senescence. However, the mechanisms underlying this process are unclear. We examined whether endothelial cell (EC)-derived microparticles (MPs) facilitate EC senescence and questioned the role of reactive oxygen species in this process.

METHODS AND RESULTS

Senescence was induced by sequential passaging of primary mouse ECs. Cells retained phenotypic characteristics of ECs from passage 4 through passage 21. Passage 21 ECs exhibited features of senescence, including increased staining of senescence-associated β-galactosidase (SA-βgal), a greater percentage of cells in G(1)/G(0) phase of the cell cycle, and increased phosphorylation of p66(Shc) (P<0.05). Microparticle formation from passage 21 ECs was increased versus passage 4 ECs (∼2.2-fold increase versus passage 4, P<0.05), and the Rho kinase inhibitor fasudil blocked this increase. Exposure of passage 4 ECs to MPs shifted cells from a proliferating to a nonproliferating phenotype, as indicated by cell cycle analysis and increased senescence-associated β-galactosidase staining. MPs increased EC generation of O(2) (•-) (∼2.7-fold) and H(2)O(2) (∼2.6-fold), effects blocked by apocynin (nicotinamide adenine dinucleotide phosphate oxidase inhibitor) and rotenone (mitochondrial oxidase inhibitor) but not by allopurinol (xanthine oxidase inhibitor). MPs increased expression of cell cycle proteins p 21 cip1 and p16ink4a and stimulated phosphorylation of p66(Shc) in ECs (P<0.05 versus untreated ECs). Pretreatment with the reactive oxygen species scavenger sodium 4,5-dihydroxybenzene-1,3-disulfonate (tiron) abrogated the prosenescent effects of MPs.

CONCLUSIONS

MPs promote EC senescence through nicotinamide adenine dinucleotide phosphate oxidase- and mitochondrial-derived reactive oxygen species. Such redox-sensitive processes may be important in vascular dysfunction in aging. (J Am Heart Assoc. 2012;1:e001842 doi: 10.1161/JAHA.112.001842.).

Redox regulation of mitochondrial function

Redox-dependent processes influence most cellular functions, such as differentiation, proliferation, and apoptosis. Mitochondria are at the center of these processes, as mitochondria both generate reactive oxygen species (ROS) that drive redox-sensitive events and respond to ROS-mediated changes in the cellular redox state. In this review, we examine the regulation of cellular ROS, their modes of production and removal, and the redox-sensitive targets that are modified by their flux. In particular, we focus on the actions of redox-sensitive targets that alter mitochondrial function and the role of these redox modifications on metabolism, mitochondrial biogenesis, receptor-mediated signaling, and apoptotic pathways. We also consider the role of mitochondria in modulating these pathways, and discuss how redox-dependent events may contribute to pathobiology by altering mitochondrial function.

p66Shc, a multifaceted protein linking Erk signalling, glucose metabolism, and oxidative stress

p66Shc, a 66 kDa proto-oncogene Src collagen homologue (Shc) adaptor protein, is classically known as a signalling protein implicated in receptor tyrosine kinase signal transduction. The p66Shc isoform exerts a physiologically relevant, inhibitory signalling effect on the Erk pathway in skeletal muscle myoblasts, which is necessary for actin cytoskeleton polymerization and normal glucose transport responses. More recently, p66Shc has been also identified as a sensor of oxidative stress-induced apoptosis and as a longevity protein in mammals, actions which require Ser36 phosphorylation of the protein and consequent accumulation of intracellular reactive oxygen species. Oxidative stress plays a key role in dysfunction of several organs and tissues, and this is of interest in metabolic diseases such as type 2 diabetes. Thus changes in p66Shc expression and/or function may play an important role in the pathogenesis of type 2 diabetes and potentially serve as an effective target for its treatment.

Apurinic/apyrimidinic endonuclease 1 inhibits protein kinase C-mediated p66shc phosphorylation and vasoconstriction

AIMS

Phosphorylation of the adaptor protein p66shc is essential for p66shc-mediated oxidative stress. We investigated the role of the reducing protein/DNA repair enzyme apurinic/apyrimidinic endonuclease1 (APE1) in modulating protein kinase CβII (PKCβII)-mediated p66shc phosphorylation in cultured endothelial cells and PKC-mediated vasoconstriction of arteries.

METHODS AND RESULTS

Oxidized low-density lipoprotein (oxLDL)induced p66shc phosphorylation at serine 36 residue and PKCβII phosphorylation in mouse endothelial cells. Adenoviral overexpression of APE1 resulted in reduction of oxLDL-induced p66shc and PKCβII phosphorylation. Phorbol 12-myristate 13-acetate (PMA), which stimulates PKCs, induced p66shc phosphorylation and this was inhibited by a selective PKCβII inhibitor. Adenoviral overexpression of PKCβII also increased p66shc phosphorylation. Overexpression of APE1 suppressed PMA-induced p66shc phosphorylation. Moreover, PMA-induced p66shc phosphorylation was augmented in cells in which APE1 was knocked down. PMA increased cytoplasmic APE1 expression, compared with the basal condition, suggesting the role of cytoplasmic APE1 against p66shc phosphorylation. Finally, vasoconstriction induced by phorbol-12,13, dibutylrate, another PKC agonist, was partially inhibited by transduction of Tat-APE1 into arteries.

CONCLUSION

APE1 suppresses oxLDL-induced p66shc activation in endothelial cells by inhibiting PKCβII-mediated serine phosphorylation of p66shc, and mitigates vasoconstriction induced by activation of PKC.

At the crossroads of longevity and metabolism: the metabolic syndrome and lifespan determinant pathways

The metabolic syndrome is becoming increasingly prevalent in the general population and carries significant incremental morbidity and mortality. It is associated with multi-organ involvement and increased all-cause mortality, resembling a precocious aging process. The mechanisms that account for this phenomenon are incompletely known, but it is becoming clear that longevity genes might be involved. Experiments with overactivation or disruption of key lifespan determinant pathways, such as silent information regulator (SIR)T1, p66Shc, and mammalian target of rapamycin (TOR), lead to development of features of the metabolic syndrome in mice. These genes integrate longevity pathways and metabolic signals in a complex interplay in which lifespan appears to be strictly dependent on substrate and energy bioavailability. Herein, we describe the roles and possible interconnections of selected lifespan determinant molecular networks in the development of the metabolic syndrome and its complications, describing initial available data in humans. Additional pathways are involved in linking nutrient availability and longevity, certainly including insulin and Insulin-like Growth Factor-1 (IGF-1) signaling, as well as FOXO transcription factors. The model described in this viewpoint article is therefore likely to be an oversimplification. Nevertheless, it represents one starting platform for understanding cell biology of lifespan in relation to the metabolic syndrome.

Resveratrol regulates p66Shc activation in HaCaT cells

Skin is exposed to both endogenous and environmental oxidant agents, leading to the harmful generation of reactive oxygen species. Particular interest has been pointed on plant antioxidants, such as resveratrol, because of their wide-ranging biological activity and clinical potential. Resveratrol exerts antioxidant, metabolism-regulating and pro-apoptotic/anti-cancer effects on a variety of experimental models and has been suggested to protect skin from ultraviolet-induced photodamaging and photoaging. In parallel, also the biological significance of p66Shc, a member of the Src Homologue and Collagene homologue family with redox activity, is getting further attention. Because of the striking intersection among the activities of resveratrol with those of p66Shc, we investigated whether resveratrol would activate p66Shc in human immortalised keratinocytes (HaCaT cells), a well known and largely used model for skin keratinocytes. HaCaT cells were treated with resveratrol (10-150 μm) for different times. The effect of resveratrol on the proliferation of HaCaT cells and the activation of ERK1/2, AKT, and p66Shc was investigated by cell counting, fluorescence-activated cell sorting, and western blot analysis of total or immunoprecipitated cell extracts. In HaCaT cells, resveratrol induces dose- and time-dependent growth arrest, p66Shc-Ser36 phosphorylation, ERK1/2 phosphorylation and AKT dephosphorylation. Finally, we showed that resveratrol-induced p66Shc-Ser36 phosphorylation is dependent on ERK1/2 activation. Interestingly, these resveratrol-induced molecular effects were associated with reduced adhesion and reversible growth arrest rather than cell death pathways. This is the first evidence linking resveratrol with p66Shc and suggests that p66Shc may contribute to the effect of resveratrol on cell proliferation and function in the outermost layer of the skin.

Mitochondria and aging in the vascular system

This review focuses on mitochondrial abnormalities that occur in the vasculature during aging and explores the link between mitochondrial oxidative stress, chronic low-grade vascular inflammation, increased rate of endothelial apoptosis, and development of vascular diseases in the elderly. Therapeutic strategies targeting the mitochondria for prevention of age-associated vascular dysfunction and disease in old age are considered here based on emerging knowledge of the vasoprotective effects of caloric restriction, caloric restriction mimetics, the GH/IGF-1 axis, and mitochondria-targeted antioxidants.

Potential therapeutic benefits of strategies directed to mitochondria

The mitochondrion is the most important organelle in determining continued cell survival and cell death. Mitochondrial dysfunction leads to many human maladies, including cardiovascular diseases, neurodegenerative disease, and cancer. These mitochondria-related pathologies range from early infancy to senescence. The central premise of this review is that if mitochondrial abnormalities contribute to the pathological state, alleviating the mitochondrial dysfunction would contribute to attenuating the severity or progression of the disease. Therefore, this review will examine the role of mitochondria in the etiology and progression of several diseases and explore potential therapeutic benefits of targeting mitochondria in mitigating the disease processes. Indeed, recent advances in mitochondrial biology have led to selective targeting of drugs designed to modulate and manipulate mitochondrial function and genomics for therapeutic benefit. These approaches to treat mitochondrial dysfunction rationally could lead to selective protection of cells in different tissues and various disease states. However, most of these approaches are in their infancy.

Mechanisms of vascular aging: new perspectives

This review focuses on molecular, cellular, and functional changes that occur in the vasculature during aging; explores the links between mitochondrial oxidative stress, inflammation, and development of vascular disease in the elderly patients; and provides a landscape of molecular mechanisms involved in cellular oxidative stress resistance, which could be targeted for the prevention or amelioration of unsuccessful vascular aging. Practical interventions for prevention of age-associated vascular dysfunction and disease in old age are considered here based on emerging knowledge of the effects of anti-inflammatory treatments, regular exercise, dietary interventions, and caloric restriction mimetics.

Anti-aging medicine: molecular basis for endothelial cell-targeted strategies - a mini-review

Due to improvements in lifestyle and healthcare, the proportion of aged people is rising steadily, especially in developed countries. With aging, some physiological functions are altered and resemble those occurring in disease conditions such as hypertension, chronic coronary disease and diabetes. Thus, there is the urge to better understand molecular and cellular mechanisms underlying aging and aging-related diseases. In rodents and possibly primates, calorie restriction is an effective approach to extend lifespan by reducing free radical-induced damage. Increased production of oxygen-derived free radicals plays an important role in the process of aging. Reactive oxygen species are generated by different intracellular molecular pathways principally located in the cytoplasm and in the mitochondria. The mitochondrial protein p66(Shc) is considered a longevity assurance gene since its genetic deletion extends the lifespan of rodents and displays protective effects in several models of cardiovascular disease. Silent mating type information regulation 2 homolog 1 Saccharomyces cerevisiae (SIRT1) is a nicotinamide adenine dinucleotide (NAD+)-dependent histone deacetylase that may also be involved in aging and diseases. SIRT1 also deacetylates a number of nonhistone target proteins, including p53, endothelial nitric oxide synthase and forkhead box protein. This review focuses on the latest scientific advances in understanding aging as well as delineates the possible therapeutic implications of p66(Shc) and SIRT1 in this process.

Identification of Peroxiredoxin 1 as a novel interaction partner for the lifespan regulator protein p66Shc

Damage caused by reactive oxygen species (ROS) contributes to many aging processes and accompanying diseases. ROS are toxic side products of cellular respiration, but also function as signal, e.g. in the mitochondrial apoptosis pathway. The protein p66Shc, which has been implicated in life-span regulation and aging-related diseases, is a central player in stress-induced apoptosis and the associated ROS burst. Stress signals, such as UV radiation or ROS themselves, activate p66Shc, which was proposed to stimulate its H₂O₂ forming activity, ultimately triggering mitochondrial disintegration. However, mechanistic details of H₂O₂ formation and apoptosis induction by p66Shc and regulation of these activities remain to be revealed. Here, we describe the effects of Ser36 phosphorylation and Pin1 binding on p66Shc activity, and the identification of Peroxiredoxin 1 (Prx1) as a novel interaction partner for the unique p66Shc N-terminal domain. Prx1 was identified in affinity experiments as dominant interaction partner. Complex formation leads to disassembly of Prx1 decamers, which is known to increase its peroxidase activity. The interaction leads to reduction of the p66CH2CB tetramer, which reduces its ability to induce mitochondrial rupture. Our results indicate that p66CH2CB and Prx1 form a stress-sensing complex that keeps p66Shc inactive at moderate stress levels.

Habitual exercise and arterial aging

Aging affects the function and structure of arteries and increases the risk of cardiovascular diseases (CVD). In healthy sedentary adults, aging is associated with increased stiffness (reduced compliance) of large elastic arteries; impaired vascular endothelial function, including reductions in endothelium-dependent dilation (EDD), release of tissue-type plasminogen activator (fibrinolytic capacity) and endothelial progenitor cell number and function; increased intima-media wall thickness (IMT); and peripheral vasoconstriction (decreased basal leg blood flow). Habitual physical activity/increased aerobic exercise capacity is associated with reduced risk of CVD. Compared with their sedentary peers, adults who regularly perform aerobic exercise demonstrate smaller or no age-associated increases in large elastic artery stiffness, reductions in vascular endothelial function, and increases in femoral artery IMT. A short-term, moderate-intensity aerobic exercise intervention (brisk daily walking for 12 wk) improves carotid artery compliance and can restore vascular endothelial function in previously sedentary middle-aged and older adults. Reduced oxidative stress may be an important mechanism contributing to these effects. Habitual resistance exercise increases (high-intensity) or does not affect (moderate-intensity) large elastic artery stiffness, and prevents/restores the age-associated reduction in basal leg blood flow independent of changes in leg fat-free mass. Habitual exercise favorably modulates several expressions of arterial aging, thus preserving vascular function and possibly reducing the risk of CVD.