Upregulation of sestrin-2 expression protects against endothelial toxicity of angiotensin II

Evaluation of sestrin 2 and tribbles homolog 3 levels in obese and nonobese women with polycystic ovary syndrome

Background/aim

This study was designed to evaluate the relationship of two new biomarkers [tribbles homolog 3 (TRB3) and sestrin 2 levels], which were previously associated with obesity, with metabolic parameters in obese and nonobese women with polycystic ovary syndrome (PCOS).

Materials and methods

This cross-sectional case control study was conducted between September 2017 and August 2019 in the gynecology department of a tertiary referral hospital. The values of the plasma sestrin 2, TRB3, insulin, fasting plasma glucose, lipid profile, and homeostasis model assessment of insulin resistance (HOMA-IR) were compared in 90 obese women with PCOS (BMI > 30), 90 women with nonobese PCOS (BMI < 30), and 90 control patients (BMI < 30).

Results

The mean age of the study group consisting of all PCOS patients (26.11 ± 4.64 years) and the mean age of the control group (26.3 ± 4.4 years) were statistically similar (p = 0.239). The serum sestrin 2 values of the obese PCOS group were found to be statistically significantly lower than the control and non-obese PCOS groups (p = 0.001, p = 0.0001), while the sestrin 2 values of the nonobese PCOS group were found to be statistically significantly lower than the control group (p = 0.0001). The TRB3 values of the control group were found to be statistically significantly lower than the obese and nonobese PCOS groups (p = 0.0001), while the TRB3 values of the nonobese PCOS group were found to be statistically significantly lower than the obese PCOS group (p = 0.0001). A negative correlation was observed between the sestrin 2 level and BMI (r = -0.272 p = 0.0001), insulin (r = -0.261 p = 0.0001), and HOMA-IR levels (r = -0.250 p = 0.0001). A positive correlation was observed between the TRB3 values and TG (r = 0.248 p = 0.0001), and LDL-C values (r = 0.235 p = 0.0001).

Conclusion

According to the findings in this study, low sestrin 2 and high TRB3 levels may be related to impaired metabolic status in the obese PCOS group. Thus, it may be promising for the development of treatment of PCOS and associated metabolic disorder in the future.

A cross-talk between sestrins, chronic inflammation and cellular senescence governs the development of age-associated sarcopenia and obesity

The rapid increase in both the lifespan and proportion of older adults is accompanied by the unprecedented rise in age-associated chronic diseases, including sarcopenia and obesity. Aging is also manifested by increased susceptibility to multiple endogenous and exogenous stresses enabling such chronic conditions to develop. Among the main physiological regulators of cellular adaption to various stress stimuli, such as DNA damage, hypoxia, and oxidative stress, are sestrins (Sesns), a family of three evolutionarily conserved proteins, Sesn1, 2, and 3. Age-associated sarcopenia and obesity are characterized by two key processes: (i) accumulation of senescent cells in the skeletal muscle and adipose tissue and (ii) creation of a systemic, chronic, low-grade inflammation (SCLGI). Presumably, failed SCLGI resolution governs the development of these chronic conditions. Noteworthy, Sesns activate senolytics, which are agents that selectively eliminate senescent cells, as well as specialized pro-resolving mediators, which are factors that physiologically provide inflammation resolution. Sesns reveal clear beneficial effects in pre-clinical models of sarcopenia and obesity. Based on these observations, we propose a novel treatment strategy for age-associated sarcopenia and obesity, complementary to the conventional therapeutic modalities: Sesn activation, SCLGI resolution, and senescent cell elimination.

Sestrin2 as a Protective Shield against Cardiovascular Disease

A timely and adequate response to stress is inherently present in each cell and is important for maintaining the proper functioning of the cell in changing intracellular and extracellular environments. Disruptions in the functioning or coordination of defense mechanisms against cellular stress can reduce the tolerance of cells to stress and lead to the development of various pathologies. Aging also reduces the effectiveness of these defense mechanisms and results in the accumulation of cellular lesions leading to senescence or death of the cells. Endothelial cells and cardiomyocytes are particularly exposed to changing environments. Pathologies related to metabolism and dynamics of caloric intake, hemodynamics, and oxygenation, such as diabetes, hypertension, and atherosclerosis, can overwhelm endothelial cells and cardiomyocytes with cellular stress to produce cardiovascular disease. The ability to cope with stress depends on the expression of endogenous stress-inducible molecules. Sestrin2 (SESN2) is an evolutionary conserved stress-inducible cytoprotective protein whose expression is increased in response to and defend against different types of cellular stress. SESN2 fights back the stress by increasing the supply of antioxidants, temporarily holding the stressful anabolic reactions, and increasing autophagy while maintaining the growth factor and insulin signaling. If the stress and the damage are beyond repair, SESN2 can serve as a safety valve to signal apoptosis. The expression of SESN2 decreases with age and its levels are associated with cardiovascular disease and many age-related pathologies. Maintaining sufficient levels or activity of SESN2 can in principle prevent the cardiovascular system from aging and disease.

Sestrin2: multifaceted functions, molecular basis, and its implications in liver diseases

Sestrin2 (SESN2), a highly conserved stress-responsive protein, can be triggered by various noxious stimuli, such as hypoxia, DNA damage, oxidative stress, endoplasmic reticulum (ER) stress, and inflammation. Multiple transcription factors regulate SESN2 expression, including hypoxia-inducible factor 1 (HIF-1), p53, nuclear factor E2-related factor 2 (Nrf2), activating transcription factor 4 (ATF4), ATF6, etc. Upon induction, SESN2 generally leads to activation of adenosine monophosphate-activated protein kinase (AMPK) and inhibition of mechanistic target of rapamycin complex 1 (mTORC1). To maintain cellular homeostasis, SESN2 and its downstream molecules directly scavenge reactive oxygen species or indirectly influence the expression patterns of key genes associated with redox, macroautophagy, mitophagy, ER stress, apoptosis, protein synthesis, and inflammation. In liver diseases including acute liver injury, fatty liver diseases, hepatic fibrosis, and hepatocellular carcinoma (HCC), SESN2 is abnormally expressed and correlated with disease progression. In NAFLD, SESN2 helps with postponing disease progression through balancing glycolipid metabolism and macroautophagy (lipophagy), and rectifying oxidative damage and ER stress. During hepatic fibrosis, SESN2 represses HSCs activation and intrahepatic inflammation, hindering the occurrence and progress of fibrogenesis. However, the role of SESN2 in HCC is controversial due to its paradoxical pro-autophagic and anti-apoptotic effects. In conclusion, this review summarizes the biological functions of SESN2 in hypoxia, genotoxic stress, oxidative stress, ER stress, and inflammation, and specifically emphasizes the pathophysiological significance of SESN2 in liver diseases, aiming to providing a comprehensive understanding for SESN2 as a potential therapeutic target in liver diseases.

Sestrin2 Signaling Pathway Regulates Podocyte Biology and Protects against Diabetic Nephropathy

Sestrin2 regulates cell homeostasis and is an upstream signaling molecule for several signaling pathways. Sestrin2 leads to AMP-activated protein kinase- (AMPK-) and GTPase-activating protein activity toward Rags (GATOR) 1-mediated inhibition of mammalian target of rapamycin complex 1 (mTORC1), thereby enhancing autophagy. Sestrin2 also improves mitochondrial biogenesis via AMPK/Sirt1/peroxisome proliferator-activated receptor-gamma coactivator 1 alpha (PGC-1α) signaling pathway. Blockade of ribosomal protein synthesis and augmentation of autophagy by Sestrin2 can prevent misfolded protein accumulation and attenuate endoplasmic reticulum (ER) stress. In addition, Sestrin2 enhances P62-mediated autophagic degradation of Keap1 to release nuclear factor erythroid 2-related factor 2 (Nrf2). Nrf2 release by Sestrin2 vigorously potentiates antioxidant defense in diabetic nephropathy. Impaired autophagy and mitochondrial biogenesis, severe oxidative stress, and ER stress are all deeply involved in the development and progression of diabetic nephropathy. It has been shown that Sestrin2 expression is lower in the kidney of animals and patients with diabetic nephropathy. Sestrin2 knockdown aggravated diabetic nephropathy in animal models. In contrast, upregulation of Sestrin2 enhanced autophagy, mitophagy, and mitochondrial biogenesis and suppressed oxidative stress, ER stress, and apoptosis in diabetic nephropathy. Consistently, overexpression of Sestrin2 ameliorated podocyte injury, mesangial proliferation, proteinuria, and renal fibrosis in animal models of diabetic nephropathy. By suppressing transforming growth factor beta (TGF-β)/Smad and Yes-associated protein (YAP)/transcription enhancer factor 1 (TEF1) signaling pathways in experimental models, Sestrin2 hindered epithelial-mesenchymal transition and extracellular matrix accumulation in diabetic kidneys. Moreover, modulation of the downstream molecules of Sestrin2, for instance, augmentation of AMPK or Nrf2 signaling and inhibition of mTORC1, has been protective in diabetic nephropathy. Regarding the beneficial effects of Sestrin2 on diabetic nephropathy and its interaction with several signaling molecules, it is worth targeting Sestrin2 in diabetic nephropathy.

Sestrin2 induction contributes to anti-inflammatory responses and cell survival by globular adiponectin in macrophages

Adiponectin, an adipose tissue-derived hormone, exhibits a modulatory effect on cell death/survival and possesses potent anti-inflammatory properties. However, the underlying molecular mechanisms remain elusive. Sestrin2, a stress-inducible metabolic protein, has shown cytoprotective and inflammation-modulatory effects under stressful conditions. In this study, we examined the role of sestrin2 signaling in the modulation of cell survival and inflammatory responses by globular adiponectin (gAcrp) in macrophages. We observed that gAcrp induced a significant increase in sestrin2 expression in both RAW 264.7 murine macrophages and primary murine macrophages. Notably, gAcrp treatment markedly increased expression of hypoxia inducible factor-1 α (HIF-1α) and gene silencing of HIF-1α blocked sestrin2 induction by gAcrp. In addition, pretreatment with a pharmacological inhibitor of ERK or PI3K abrogated both sestrin2 and HIF-1α expression by gAcrp, indicating that ERK/PI3K-mediated HIF-1α signaling pathway plays a critical role in sestrin2 induction by gAcrp. Furthermore, sestrin2 induction is implicated in autophagy activation, and knockdown of sestrin2 prevented enhanced cell viability by gAcrp. Moreover, gene silencing of sestrin2 caused restoration of gAcrp-induced expression of anti-inflammatory genes in a gene-selective manner. Taken together, these results indicate that sestrin2 induction critically contributes to cell survival and anti-inflammatory responses by gAcrp in macrophages.

Target Sestrin2 to Rescue the Damaged Organ: Mechanistic Insight into Its Function

Sestrin2 is a stress-inducible metabolic regulator and a conserved antioxidant protein which has been implicated in the pathogenesis of several diseases. Sestrin2 can protect against atherosclerosis, heart failure, hypertension, myocardial infarction, stroke, spinal cord injury neurodegeneration, nonalcoholic fatty liver disease (NAFLD), liver fibrosis, acute kidney injury (AKI), chronic kidney disease (CKD), and pulmonary inflammation. Oxidative stress and cellular damage signals can alter the expression of Sestrin2 to compensate for organ damage. Different stress signals such as those mediated by P53, Nrf2/ARE, HIF-1α, NF-κB, JNK/c-Jun, and TGF-β/Smad signaling pathways can induce Sestrin2 expression. Subsequently, Sestrin2 activates Nrf2 and AMPK. Furthermore, Sestrin2 is a major negative regulator of mTORC1. Sestrin2 indirectly regulates the expression of several genes and reprograms intracellular signaling pathways to attenuate oxidative stress and modulate a large number of cellular events such as protein synthesis, cell energy homeostasis, mitochondrial biogenesis, autophagy, mitophagy, endoplasmic reticulum (ER) stress, apoptosis, fibrogenesis, and lipogenesis. Sestrin2 vigorously enhances M2 macrophage polarization, attenuates inflammation, and prevents cell death. These alterations in molecular and cellular levels improve the clinical presentation of several diseases. This review will shed light on the beneficial effects of Sestrin2 on several diseases with an emphasis on underlying pathophysiological effects.

Exercise improves lipid metabolism disorders induced by high-fat diet in a SESN2/JNK-independent manner

SESN2 and JNK are emerging powerful stress-inducible proteins in regulating lipid metabolism. The aim of this study was to determine the underlying mechanism of SESN2/JNK signaling in exercise to improve lipid disorder induced by high-fat diet (HFD). Our data showed that HFD and SESN2 knockout resulted in abnormalities including elevated body weight, increased fat mass, serum total cholesterol, lipid biosynthesis related proteins, and a concomitant increase of pJNK-Thr183/Tyr185. The above changes were reversed by exercise training. SESN2 silencing or JNK inhibition in palmitate-treated C2C12 further confirmed that SESN2 and JNK play a vital role in lipid biosynthesis. Rescue experiment further demonstrated that SESN2 reduced lipid biosynthesis through inhibition of JNK. SESN2/JNK signaling axis regulates lipid biosynthesis in both animal and cell models with abnormalities of lipid metabolism induced by HFD or palmitate treatment. This study provided evidence that exercise ameliorated lipid metabolic disorder induced by HFD feeding or by SESN2 knockout. SESN2 may improve lipid metabolism through inhibition JNK expression in skeletal muscle cells, providing a molecular mechanism that may represent an attractive target for the treatment of lipid disorder. Novelty: Exercise improved lipid disorder induced by HFD feeding and SESN2 knockout. SESN2 and JNK play a vital role in lipid biosynthesis in vivo and in vitro. SESN2 suppressed JNK to improve lipid metabolism in skeletal muscle cells.

Sestrin2 in atherosclerosis

Atherosclerosis (AS) is the pathological basis of numerous lethal diseases, such as myocardial infarction, heart failure, and stroke. As we know, almost twenty million people worldwide die of the arterial diseases annually. Sestrin2 is a stress-inducing protein, which serves as a guardian by activating AMPK, inhibiting mTOR, and maintaining redox balance beneath various stress environments. A large number of studies show that Sestrin2 would shield the body from injury by stress. Moreover, it has been demonstrated that Sestrin2 is closely connected with AS. Here, this article reviewed the involvement of Sestrin2 in the pathogenesis of AS from four aspects: cellular mechanism, oxidative stress, inflammation, and lipid metabolism. Current evidence reveals that Sestrin2 is a novel target for the prevention and treatment of AS.

Sestrin2 suppression aggravates oxidative stress and apoptosis in endothelial cells subjected to pharmacologically induced endoplasmic reticulum stress

Endoplasmic reticulum (ER) stress is an inflammatory response that contributes to endothelial cell dysfunction, a hallmark of cardiovascular diseases, in close interplay with oxidative stress. Recently, Sestrin2 (SESN2) emerged as a novel stress-inducible protein protecting cells from oxidative stress. We investigated here, for the first time, the impact of SESN2 suppression on oxidative stress and cell survival in human endothelial cells subjected to pharmacologically (thapsigargin)-induced ER stress and studied the underlying cellular pathways. We found that SESN2 silencing, though did not specifically induce ER stress, it aggravated the effects of thapsigargin-induced ER stress on oxidative stress and cell survival. This was associated with a dysregulation of Nrf-2, AMPK and mTORC1 signaling pathways. Furthermore, SESN2 silencing aggravated, in an additive manner, apoptosis caused by thapsigargin. Importantly, SESN2 silencing, unlike thapsigargin, caused a dramatic decrease in protein expression and phosphorylation of Akt, a critical pro-survival hub and component of the AMPK/Akt/mTORC1 axis. Our findings suggest that patients with conditions characterized by ER stress activation, such as diabetes, may be at higher risk for cardiovascular complications if their endogenous ability to stimulate and/or maintain expression levels of SESN2 is disturbed or impaired. Therefore, identifying novel or repurposing existing pharmacotherapies to enhance and/or maintain SESN2 expression levels would be beneficial in these conditions.

Sestrin 2, a potential star of antioxidant stress in cardiovascular diseases

Physiological reactive oxygen species (ROS) play an important role in cellular signal transduction. However, excessive ROS is an important pathological mechanism in most cardiovascular diseases (CVDs), such as myocardial aging, cardiomyopathy, ischemia/reperfusion injury (e.g., myocardial infarction) and heart failure. Programmed cell death, hypertrophy and fibrosis may be due to oxidative stress. Sestrin 2 (Sesn2), a stress-inducible protein associated with various stress conditions, is a potential antioxidant. Sesn2 can suppress the process of heart damage caused by oxidative stress, promote cell survival and play a key role in a variety of CVDs. This review discusses the effect of Sesn2 on the redox signal, mainly via participation in the signaling pathway of nuclear factor erythroid 2-related factor 2, activation of adenosine monophosphate-activated protein kinase and inhibition of mammalian target of rapamycin complex 1. It also discusses the effect of Sesn2's antioxidant activity on different CVDs. We speculate that Sesn2 plays an important role in CVDs by stimulating the process of antioxidation and promoting the adaptation of cells to stress conditions and/or the environment, opening a new avenue for related therapeutic strategies.

The Protective Role of Sestrin2 in Atherosclerotic and Cardiac Diseases

Atherosclerotic disease, such as coronary artery disease (CAD), is known to be a chronic inflammatory disease, as well as an age-related disease. Excessive oxidative stress produced by reactive oxygen species (ROS) contributes to the pathogenesis of atherosclerosis. Sestrin2 is an anti-oxidant protein that is induced by various stresses such as hypoxia, DNA damage, and oxidative stress. Sestrin2 is also suggested to be associated with aging. Sestrin2 is expressed and secreted mainly by macrophages, endothelial cells, and cardiomyocytes. Sestrin2 plays an important role in suppressing the production and accumulation of ROS, thus protecting cells from oxidative damage. Since sestrin2 is reported to have anti-oxidant and anti-inflammatory properties, it may play a protective role against the progression of atherosclerosis and may be a potential therapeutic target for the amelioration of atherosclerosis. Regarding the association between blood sestrin2 levels and atherosclerotic disease, the blood sestrin2 levels in patients with CAD or carotid atherosclerosis were reported to be high. High blood sestrin2 levels in patients with such atherosclerotic disease may reflect a compensatory response to increased oxidative stress and may help protect against the progression of atherosclerosis. This review describes the protective role of sestrin2 against the progression of atherosclerotic and cardiac diseases.

Regulatory mechanisms of Sesn2 and its role in multi-organ diseases

Sestrin2 (Sesn2) is a powerful anti-oxidant that can prevent acute and chronic diseases. The role of Sesn2 has been thoroughly reviewed in liver, nervous system, and immune system diseases. However, there is a limited number of reviews that have summarized the effects of Sesn2 in heart and vascular diseases, and very less literature-based information is available on involvement of Sesn2 in renal and respiratory pathologies. This review summarizes the latest research on Sesn2 in multi-organ stress responses, with a particular focus on the protective role of Sesn2 in cardiovascular, respiratory, and renal diseases, emphasizing the potential therapeutic benefit of targeting Sesn2 in stress-related diseases.

Sesn2 attenuates the damage of endothelial progenitor cells induced by angiotensin II through regulating the Keap1/Nrf2 signal pathway

Endothelial progenitor cell (EPC) dysfunction is an important physiopathological mechanism in the dynamics of the formation of atherosclerosis. It has been reported that angiotensin II (Ang-II) damages the function of EPCs in atherosclerotic plaque through induction of oxidative stress. Sestrin 2 (Sesn2) serves as an antioxidant role in oxidative stress, however, the exact mechanisms underlying the dynamics of how Sesn2 may factor into EPCs after Ang-II treatments needs to be illustrated. We isolated EPCs from human umbilical cord blood samples and treated with Ang-II. Western blotting, qRT-PCR, transwell assays, immunofluorescence and so on were used to investigate the mechanisms underlying the roles of Sesn2 in EPCs treated with Ang-II. Ang-II was found to promote the apoptosis of EPCs as well as inhibited the mRNA and protein expression of Sesn2. Upregulation of Sesn2 attenuated the negative effect of Ang-II. Sesn2 increased the protein expression of Nrf2 by enhancing P62-dependent autophagy. Silencing of Nrf2 enhanced the degree of apoptosis of EPCs as well as resulted in the impairment of EPC functions through inducing the promotion of (reactive oxygen species) ROS production. Our study results indicated that Sesn2 facilitated the viability of EPCs After treatment with Ang-II, as well as provided a potential therapeutic target to alleviate the progression of atherosclerosis.

Sestrin 2 controls the cardiovascular aging process via an integrated network of signaling pathways

As an inevitable biological process, cardiovascular aging is the greatest risk factor for cardiovascular diseases (CVDs). Sestrin 2 (Sesn2), a stress-inducible and age-related protein associated with various stress conditions, plays a pivotal role in slowing this process. It acts as an anti-aging agent, mainly through its antioxidant enzymatic activity and regulation of antioxidant signaling pathways, as well as by activating adenosine monophosphate-activated protein kinase and inhibiting mammalian target of rapamycin complex 1. In this review, we first introduce the biochemical functions of Sesn2 in the cardiovascular aging process, and describe how Sesn2 expression is regulated under various stress conditions. Next, we emphasize the role of Sesn2 signal transduction in a series of age-related CVDs, including hypertension, myocardial ischemia and reperfusion, atherosclerosis, and heart failure, as well as provide potential mechanisms for the association of Sesn2 with CVDs. Finally, we present the potential therapeutic applications of Sesn2-directed therapy and future prospects.

Association between Plasma Sestrin2 Levels and the Presence and Severity of Coronary Artery Disease

Aims

Atherosclerotic disease, such as coronary artery disease (CAD), is recognized to be associated with inflammation and oxidative stress. We investigated the association between CAD and plasma levels of sestrin2 which is one of the stress-inducible antioxidant proteins.

Methods

We measured plasma sestrin2 levels in 304 patients undergoing elective coronary angiography. The severity of CAD was represented as the numbers of >50% stenotic coronary vessels and segments and the severity score.

Results

CAD was found in 175 patients, of whom 73 had 1-vessel (1-VD), 59 had 2-vessel (2-VD), and 43 had 3-vessel disease (3-VD). Plasma sestrin2 levels were significantly higher in 175 patients with CAD than in 129 without CAD (median 16.4 vs. 14.2 ng/mL, P < 0.05). A stepwise increase in sestrin2 levels was found depending on the number of >50% stenotic coronary vessels: 14.2 in CAD(-), 15.4 in 1-VD, 17.3 in 2-VD, and 17.7 ng/mL in3-VD (P < 0.05). High sestrin2 level (>16.0 ng/mL) was present in 38% of patients with CAD(-), 47% of 1-VD, 66% of 2-VD, and 53% of 3-VD (P < 0.005). Sestrin2 levels significantly, but weakly, correlated with the number of >50% stenotic segments and the severity score (rs = 0.12 and rs = 0.13, P < 0.05). In the multivariate analysis, sestrin2 levels were a significant factor associated with CAD independent of atherosclerotic risk factors. The odds ratio for CAD was 1.79 (95%CI = 1.09-2.95) for high sestrin2 level of >16.0 ng/mL (P < 0.025).

Conclusions

Plasma sestrin2 levels in patients with CAD were found to be high and to be associated with the severity of CAD. High sestrin2 levels in patients with CAD may reflect a protective response against the progression of CAD.

Circulating Sestrin Levels Are Increased in Hypertension Patients

Background

Sestrins (Sesns), a group of oxidative stress-related proteins, have been reported to be involved in various cardiovascular diseases, including aortic dissection and chronic heart failure. This study is aimed at investigating the level of circulating Sesn1, Sesn2, and Sesn3 in hypertension patients.

Methods

Plasma levels of Sesn1, Sesn2, and Sesn3 in 400 hypertensive patients and 100 normotensive subjects were detected using enzyme-linked immunosorbent assay (ELISA) kits. The hypertension patients were divided into groups with grade I (n = 140), grade II (n = 180), and grade III (n = 80) hypertension.

Results

Compared with the normotensive subjects, Sesn1, Sesn2, and Sesn3 levels were increased in patients with hypertension, with a gradual increase between the groups with grade I, grade II, and grade III hypertension. Elevated Sesn1, Sesn2, and Sesn3 levels were positively correlated with both the systolic blood pressure (SBP) and diastolic blood pressure (DBP). Moreover, Sesn1, Sesn2, and Sesn3 levels were elevated in patients with dipper hypertension and further increased in patients with nondipper hypertension. In addition, smokers, as well as patients with higher levels of angiotensin II (Ang II) and carotid atherosclerotic plaque (CAP), exhibited increased Sesn1, Sesn2, and Sesn3 levels when compared with patients without these clinical characteristics. Furthermore, plasma levels of Sesn1, Sesn2, and Sesn3 were negatively correlated with the presence of CAP.

Conclusions

Circulating Sesn levels are increased in patients with hypertension and may be a target for the prevention and treatment of clinical hypertension.

Sestrin2 as a potential therapeutic target for cardiovascular diseases

Sestrin2 is a cysteine sulfinyl reductase that plays crucial roles in regulation of antioxidant actions. Sestrin2 provides cytoprotection against multiple stress conditions, including hypoxia, endoplasmic reticulum (ER) stress and oxidative stress. Recent research reveals that upregulation of Sestrin2 is induced by various transcription factors such as p53 and activator protein 1 (AP-1), which further promotes AMP-activated protein kinase (AMPK) activation and inhibits mammalian target of rapamycin protein kinase (mTOR) signaling. Sestrin2 triggers autophagy activity to reduce cellular reactive oxygen species (ROS) levels by promoting nuclear factor erythroid 2 (NF-E2)-related factor 2 (Nrf2) activation and Kelch-like ECH-associated protein 1 (Keap1) degradation, which plays a pivotal role in homeostasis of metabolic regulation. Under hypoxia and ER stress conditions, elevated Sestrin2 expression maintains cellular homeostasis through regulation of antioxidant genes. Sestrin2 is responsible for diminishing cellular ROS accumulation through autophagy via AMPK activation, which displays cardioprotection effect in cardiovascular diseases. In this review, we summarize the recent understanding of molecular structure, biological roles and biochemical functions of Sestrin2, and discuss the roles and mechanisms of Sestrin2 in autophagy, hypoxia and ER stress. Understanding the precise functions and exact mechanism of Sestrin2 in cellular homeostasis will provide the evidence for future experimental research and aid in the development of novel therapeutic strategies for cardiovascular diseases.

Sestrin2 alleviates palmitate-induced endoplasmic reticulum stress, apoptosis, and defective invasion of human trophoblast cells

PROBLEM

Maternal obesity induces elevated saturated fatty acid palmitate levels in the blood and causes pregnancy complications such as gestational diabetes, preeclampsia, fetal growth abnormalities, and stillbirth. Sestrin2, a highly conserved stress-inducible protein, is involved in the cellular responses of various stress conditions and homeostatic regulation. However, the effects of Sestrin2 on trophoblast cells have not yet been investigated. Here, we investigated the role of Sestrin2 in palmitate-induced lipotoxicity and its underlying mechanisms in human first-trimester trophoblast cells (Sw.71).

METHOD OF STUDY

Mouse placental tissues were obtained from low-fat diet-fed mice (n = 14) and high-fat diet-fed mice (n = 14) at gestation day 17.5. Sw.71 cells were treated with palmitate or bovine serum albumin as vehicle controls. The role of Sestrin2 in palmitate-induced lipotoxicity was examined by immunocytochemistry, immunoblot analysis, quantitative real-time PCR, and invasion assay.

RESULTS

Expression of placental Sestrin2 was elevated in high-fat diet-fed dams compared to that of low-fat diet-fed dams. Prolonged treatment of Sw.71 cells with palmitate-induced endoplasmic reticulum (ER) stress-dependent expressions of Sestrin2 protein and mRNA, and the treatment also triggered apoptosis. Knockdown of Sestrin2 increased palmitate-mediated ER stress, inflammatory signaling, and apoptosis. Furthermore, Sestrin2 suppressed impaired trophoblast invasion caused by palmitate and attenuated palmitate-induced ER stress and inflammation via AMPK/mTORC1 pathways.

CONCLUSION

Our study provides the relationship between Sestrin2, AMPK/mTORC1 pathway, and trophoblast function, suggesting that Sestrin2 may be a novel potential therapeutic target for the prevention of pregnancy complications.

Plasma sestrin2 concentrations and carotid atherosclerosis

BACKGROUND

Sestrin2 is a stress-inducible antioxidant protein that plays a protective role against oxidative stress. However, blood sestrin2 concentrations in subjects with carotid atherosclerosis have not been elucidated.

METHODS

We investigated plasma sestrin2 concentrations in 152 subjects undergoing carotid ultrasonography. Plaque severity was evaluated as plaque score.

RESULTS

Of the 152 subjects, plaque was found in 63 (41%). Plasma sestrin2 concentrations were higher in 63 subjects with plaque than in 89 without plaque (median 14.1 vs. 12.8 ng/ml, P < 0.02). A stepwise increase in sestrin2 concentrations was found depending on plaque score: 12.8 ng/ml in score = 0 (n = 89), 12.7 ng/ml in score = 1 (n = 31), and 15.9 ng/ml in score ≥2 (n = 32)(P < 0.005). Especially, sestrin2 concentrations in subjects with score ≥ 2 were higher than in score = 0 and score = 1 (P < 0.05). Sestrin2 concentrations correlated with plaque score (r = 0.24, P < 0.005). In multivariate analysis, sestrin2 concentration was an independent factor associated with score ≥ 2. Odds ratio for score ≥ 2 was 5.70 (95%CI = 1.99-16.35) for high sestrin2 concentration (>13.0 ng/ml).

CONCLUSION

Plasma sestrin2 concentrations were found to be high in subjects with carotid plaque and to be associated with plaque severity. High plasma sestrin2 concentrations in subjects with carotid plaque may reflect a protective response against the progression of carotid atherosclerosis.

ER stress contributes to autophagy induction by adiponectin in macrophages: Implication in cell survival and suppression of inflammatory response

Adiponectin, the most abundant adipokine, exhibits various physiological functions. In addition to its critical role in lipid metabolism, recent studies have demonstrated its potent anti-inflammatory and cytoprotective properties. Accumulating evidence suggests that autophagy plays a critical role in various biological responses by adiponectin. However, the underlying mechanisms remain elusive. Herein, we investigated the role of ER stress in adiponectin-induced autophagy and its functional roles in biological responses by adiponectin in macrophages. In this study, globular adiponectin (gAcrp) significantly increased the expression of various ER stress markers in both RAW 264.7 and primary peritoneal macrophages. In addition, inhibition of ER stress by treatment with tauroursodeoxycholic acid (TUDCA) or gene silencing of CHOP prominently suppressed gAcrp-induced autophagy. Treatment with gAcrp also induced significant increase in sestrin2 expression. Interestingly, knockdown of sestrin2 prevented autophagy induction and inhibition of ER stress abrogated sestrin2 induction by gAcrp, collectively implying that ER stress critically contributes to gAcrp-induced autophagy activation via sestrin2 induction. Moreover, pretreatment with TUDCA restored suppression of TNF-α and IL-1β expression and attenuated the enhanced viability of macrophages induced by gAcrp. Taken together, these findings indicate the potential role of ER stress in autophagy activation, modulation of inflammatory responses, and cell survival by gAcrp in macrophages.

Sestrin2: Its Potential Role and Regulatory Mechanism in Host Immune Response in Diseases

Sestrin2 (SESN2), a highly evolutionarily conserved protein, is critically involved in cellular responses to various stresses. SESN2 has a protective effect on physiological and pathological states mainly via regulating oxidative stress, endoplasmic reticulum stress, autophagy, metabolism, and inflammation. In recent years, breakthrough investigations with regard to the regulation and signaling mechanisms of SESN2 have markedly deepened our understanding of its potential role as well as its significance in host response. However, the functions of SESN2 in the immune system and inflammation remain elusive. It has been documented that many immune cells positively express SESN2 and, in turn, that SESN2 might modulate cellular activities. This review incorporates recent progress and aims to provide novel insight into the protective role and regulatory pathway of SESN2, which acts as a potential biomarker and therapeutic target in the context of various diseases.

A multi-ancestry genome-wide study incorporating gene-smoking interactions identifies multiple new loci for pulse pressure and mean arterial pressure

Elevated blood pressure (BP), a leading cause of global morbidity and mortality, is influenced by both genetic and lifestyle factors. Cigarette smoking is one such lifestyle factor. Across five ancestries, we performed a genome-wide gene-smoking interaction study of mean arterial pressure (MAP) and pulse pressure (PP) in 129 913 individuals in stage 1 and follow-up analysis in 480 178 additional individuals in stage 2. We report here 136 loci significantly associated with MAP and/or PP. Of these, 61 were previously published through main-effect analysis of BP traits, 37 were recently reported by us for systolic BP and/or diastolic BP through gene-smoking interaction analysis and 38 were newly identified (P < 5 × 10-8, false discovery rate < 0.05). We also identified nine new signals near known loci. Of the 136 loci, 8 showed significant interaction with smoking status. They include CSMD1 previously reported for insulin resistance and BP in the spontaneously hypertensive rats. Many of the 38 new loci show biologic plausibility for a role in BP regulation. SLC26A7 encodes a chloride/bicarbonate exchanger expressed in the renal outer medullary collecting duct. AVPR1A is widely expressed, including in vascular smooth muscle cells, kidney, myocardium and brain. FHAD1 is a long non-coding RNA overexpressed in heart failure. TMEM51 was associated with contractile function in cardiomyocytes. CASP9 plays a central role in cardiomyocyte apoptosis. Identified only in African ancestry were 30 novel loci. Our findings highlight the value of multi-ancestry investigations, particularly in studies of interaction with lifestyle factors, where genomic and lifestyle differences may contribute to novel findings.

Sestrins at the Interface of ROS Control and Autophagy Regulation in Health and Disease

Reactive oxygen species (ROS) and autophagy are two highly complex and interrelated components of cell physiopathology, but our understanding of their integration and their contribution to cell homeostasis and disease is still limited. Sestrins (SESNs) belong to a family of highly conserved stress-inducible proteins that orchestrate antioxidant and autophagy-regulating functions protecting cells from various noxious stimuli, including DNA damage, oxidative stress, hypoxia, and metabolic stress. They are also relevant modulators of metabolism as positive regulators of the key energy sensor AMP-dependent protein kinase (AMPK) and inhibitors of mammalian target of rapamycin complex 1 (mTORC1). Since perturbations in these pathways are central to multiple disorders, SESNs might constitute potential novel therapeutic targets of broad interest. In this review, we discuss the current understanding of regulatory and effector networks of SESNs, highlighting their significance as potential biomarkers and therapeutic targets for different diseases, such as aging-related diseases, metabolic disorders, neurodegenerative diseases, and cancer.

Increased plasma sestrin2 concentrations in patients with chronic heart failure and predicted the occurrence of major adverse cardiac events: A 36-month follow-up cohort study

BACKGROUND

Previous study had demonstrated that sestrin2 (Sesn2) expression was increased in human failing heart. Although, the circulating Sesn2 concentrations in patients with chronic heart failure (CHF) remains unknown. This study investigated plasma Sesn2 concentrations in patients with CHF and the role between Sesn2 and the occurrence of major adverse cardiac events.

METHODS

A total of 80 control subjects and 220 CHF patients were enrolled and the Sesn2 concentrations of each sample were measured. Additionally, the occurrence of major adverse cardiac events in each CHF patient were followed prospectively for 36 months.

RESULTS

Increased plasma Sesn2 concentrations were found in CHF patients and gradually increased from New York Heart Association (NYHA) functional class II to IV. The Sesn2 concentrations were positively correlated with N-terminal B-type natriuretic peptide (NT-pro BNP) but negatively correlated with left ventricular ejection fraction (LVEF) in CHF patients. The ROC curve suggested that Sesn2 had a certain value in predicting major adverse cardiac events during CHF patients, although, the predictive role of Sesn2 is not as good as NT-pro BNP. In addition, the multivariate Cox hazard analysis was performed after the CHF patients were divided into 3 groups (low, middle, and high) base on the plasma Sesn2 concentrations category, and the results showed that both high and middle Sesn2 concentrations increased the incidence of major adverse cardiac events when compared with low Sesn2 group. Furthermore, CHF patients with major adverse cardiac events showed higher Sesn2 concentrations when compared with CHF without major adverse cardiac events. The Kaplan-Meier analysis was performed after the CHF patients were divided into 2 groups according to the median Sesn2 concentrations and the results revealed that patients with high Sesn2 concentrations had a higher risk of major adverse cardiac events compared with those with low Sesn2.

CONCLUSIONS

Plasma Sesn2 concentrations were increased in CHF patients and positively correlated with the severity of CHF. Increased Sesn2 concentrations significantly increased the occurrence of major adverse cardiac events and suggested poor outcome in CHF patients.

Sestrin2 increases in aortas and plasma from aortic dissection patients and alleviates angiotensin II-induced smooth muscle cell apoptosis via the Nrf2 pathway

BACKGROUND

Previous studies have demonstrated that oxidative stress is closely related to aortic dissection (AD). Sestrin2 (Sesn2) is an important antioxidant protein, and this study aimed to investigate whether Sesn2 participates in AD and the possible mechanisms.

METHODS

Sesn2 expression was detected in aortas collected from AD patients and normal donors. In addition, blood samples were collected from AD patients and non-AD (NAD) patients, and the plasma Sesn2 levels were measured. Furthermore, the effects of Sesn2 on angiotensin (Ang) II-induced smooth muscle cell (SMC) apoptosis were investigated in vitro.

RESULTS

Compared with the aortas from normal donors, aortas from AD patients had significantly increased Sesn2. Sesn2 was mainly secreted by macrophages, and low levels were secreted by CD4+ T lymphocytes, but not SMCs. Plasma Sesn2 levels were also increased in AD patients compared with NAD patients. Sesn2 levels were negatively corrected with superoxide dismutase (SOD) levels but positively corrected with malondialdehyde (MDA) levels in AD patients. In co-cultures of macrophages and SMCs, Sesn2 overexpression in macrophages significantly reduced Ang II-induced SMC apoptosis, and this effect could be reversed by Nrf2 silencing.

CONCLUSIONS

Sesn2 is increased in both aortas and plasma from AD patients. Sesn2 may alleviate Ang II-induced SMC apoptosis and participate in AD via the Nrf2 pathway. Sesn2 may be a new target in the treatment and prevention of AD.

Knockdown of Sestrin2 Increases Lipopolysaccharide-Induced Oxidative Stress, Apoptosis, and Fibrotic Reactions in H9c2 Cells and Heart Tissues of Mice via an AMPK-Dependent Mechanism

Sestrin2 (sesn2) is an endogenous antioxidant protein that has recently gained attention for its potential to treat various inflammatory diseases. However, the relationship of sesn2 with cardiomyopathy is still unclear. In H9c2 cells, sesn2 knockdown reduced the level of 5′ adenosine monophosphate-activated protein kinase (AMPK) phosphorylation, downregulated antioxidant genes including catalase and superoxide dismutase (SOD2), and increased reactive oxygen species (ROS) production upon lipopolysaccharide (LPS) treatment. LPS-mediated cell death and the expression of matrix metalloproteinase (MMP) 2 and MMP9 were significantly increased by sesn2 knockdown. However, these increases were prevented by treatment with 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR), an AMPK activator. Consistent with the in vitro results, AMPK phosphorylation was decreased in heart tissue from sesn2 knockdown mice compared to heart tissue from control C57BL/6 mice, which was associated with decreased expression of antioxidant genes and increased LPS-mediated cell death signaling. Furthermore, the decrease in AMPK phosphorylation caused by sesn2 knockdown increased LPS-mediated expression of cardiac fibrotic factors, including collagen type I and type III, in addition to MMP2 and MMP9, in heart tissue from C57BL/6 mice. These results suggest that sesn2 is a novel potential therapeutic target for cardiomyopathy under inflammatory conditions.

Sestrin2 facilitates glutamine-dependent transcription of PGC-1α and survival of liver cancer cells under glucose limitation

Differential utilization of metabolites and metabolic plasticity can confer adaptation to cancer cells under metabolic stress. Glutamine is one of the vital and versatile nutrients that cancer cells consume avidly for their proliferation, and therefore mechanisms related to glutamine metabolism have been identified as targets. Recently, sestrin2 (SESN2), a stress-inducible protein, has been reported to regulate survival in glutamine-depleted cancer cells; based on this, we explored if SESN2 could regulate glutamine metabolism during glucose starvation. This report highlights the role of SESN2 in the regulation of glutamine-dependent activation of the mitochondrial biogenesis marker peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) under glucose scarcity in liver cancer cells (HepG2). We demonstrate that down-regulation of SESN2 induces a decrease in the levels of intracellular glutamine and PGC-1α under glucose deprivation, concomitant with a decline in cell survival, but no effect was observed on the invasive or migration potential of the cells. Under similar metabolic conditions, SESN2 forms a complex with c-Jun N-terminal kinase (JNK) and forkhead box protein O1 (FOXO1). Absence of SESN2 or inhibition of JNK reduces nuclear translocation of FOXO1, consequently causing transcriptional inhibition of PGC-1α. Notably, our observations demonstrate a reduction in cell viability under high glutamine and low glucose conditions during SESN2 down-regulation that could be rescued on JNK inhibition. To recover from acetaminophen-induced mitochondrial damage, SESN2 was crucial for glutamine-mediated activation of PGC-1α in HepG2 cells. Collectively, we demonstrate a novel role of SESN2 in mediating activation of PGC-1α by modulating glutamine metabolism that facilitates cancer cell survival under glucose-limited metabolic conditions.

The impact of microRNA-122 and its target gene Sestrin-2 on the protective effect of ghrelin in angiotensin II-induced cardiomyocyte apoptosis

Ghrelin with n-octanoylated serine 3 residue is a peptide hormone with well-known cardioprotective properties. MicroRNA-122 is associated with the pathogenesis of many cardiovascular diseases, including apoptosis and was found highly increased in our previous rat model of post-myocardial infarction heart failure. In this study, we aimed to identify the target gene of microRNA-122 and to evaluate their impacts on the protective effect of acylated ghrelin in angiotensin II-induced apoptosis. The results showed that microRNA-122 was upregulated in the angiotensin II administration group accompanied by increased cell apoptosis, which were both reversed by ghrelin. Furthermore, microRNA-122 mimics upregulated numerous pro-apoptotic genes and increased apoptosis. The luciferase activity assay revealed Sestrin-2 as a direct target of microRNA-122. The expression of Sestrin-2 was downregulated by angiotensin II and upregulated by co-treatment with ghrelin. Inhibition of microRNA-122 and overexpression of Sestrin-2 alleviated apoptosis which was further reduced upon administered of ghrelin. Together, these results indicated that Sestrin-2 expression is inhibited by microRNA-122 and that this inhibition is involved in the protective effect of ghrelin and angiotensin II-induced apoptosis. We also found that microRNA-122 influenced several apoptosis pathways including the caspase cascade reaction and death receptor-mediated pathways. Collectively, our data reveal that microRNA-122 and its target gene Sestrin-2, under the regulation of angiotensin II and ghrelin, are important players in cardiomyocyte apoptosis. We therefore believe that microRNA-122 and Sestrin-2 can be developed as potential therapeutic targets against apoptosis in cardiovascular diseases.

Inhibition of microRNA-122 and overexpression of Sestrin-2 alleviated angiotensin II-induced cardiomyocyte apoptosis and enhanced the protective effect of ghrelin.

Evaluation of Plasma TRB3 and Sestrin 2 Levels in Obese and Normal-Weight Children

OBJECTIVE

Obesity in childhood and adolescence is associated with metabolic syndrome and cardiovascular diseases. TRB3 (Tribbles homolog 3) and sestrin 2 are two newly found proteins that have been identified to play an important role in obesity and its complications.

AIM

The purpose of this study was to evaluate concentrations of TRB3 and sestrin 2 in plasma of obese and normal-weight children and adolescents, and their association with metabolic and anthropometric parameters.

METHODS

Plasma levels of TRB3, sestrin 2, insulin, fasting plasma glucose (FPG), and lipid profile were evaluated in 70 children and adolescents (34 obese and 36 controls). Insulin resistance was calculated using a homeostasis model assessment of insulin resistance. Metabolic syndrome was defined according to IDF criteria.

RESULTS

Plasma TRB3 levels of the obese subjects were significantly higher than that of normal weight subjects. TRB3 levels were positively correlated with BMI, BMI z-score, waist circumference, and FPG. The concentration of sestrin 2 was significantly lower in obese subjects compared to normal-weight subjects. A statistically significant positive correlation was observed between plasma concentrations of sestrin 2 and high-density lipoprotein cholesterol. Neither TRB3 nor sestrin 2 were correlated with insulin resistance and metabolic syndrome.

CONCLUSION

Both TRB3 and sestrin 2 may contribute to the development of obesity and its complications and can be considered interesting therapeutic target for the treatment of obesity.

Sestrins increase in patients with coronary artery disease and associate with the severity of coronary stenosis

BACKGROUND

Sestrins (Sesns) family, which including three members Sesn1, Sesn2 and Sesn3, is known as stress-inducible proteins and participate in multiple diseases via regulating oxidative stress, inflammatory response and cell apoptosis. The present study aimed to investigate the plasma levels and the clinical significance of Sesns in patients with coronary artery disease (CAD).

METHODS

In the case-control study, 119 CAD patients, including stable angina pectoris (SAP, n=44), unstable angina pectoris (UAP, n=41) and acute myocardial infarction (AMI, n=29) were included. Patients with chest pain syndrome but excluded CAD (n=35) were enrolled as control. Plasma levels of Sesn1, Sesn2, Sesn3, superoxide dismutase (SOD) and malondialdehyde (MDA) in all patients were measured and analyzed.

RESULTS

Compared with control group, plasma levels of Sesn1, Sesn2 and Sesn3 were significantly increased in patients with SAP, UAP and AMI. In addition, a significant lower SOD levels and higher MDA levels were observed in CAD patients, Sesn1/2/3 levels were negatively correlated with SOD levels and positively correlated with MDA levels. Gensini Score were positively correlated with Sesn1/2/3 levels and MDA levels, whereas negatively correlated with SOD levels. Furthermore, as the main risk factors for CAD, the elderly and obesity increased plasma Sesn2 levels, diabetes increased both plasma Sesn2 and Sesn3 levels.

CONCLUSIONS

Our study was the first to report that the plasma Sesns levels were increased in CAD patients and positively related to the severity of coronary heart disease. Although the exact mechanisms of Sesns in CAD are still unknown, alleviated oxidative stress may be the possible reasons.

Role of sestrin2 in H2O2-induced PC12 apoptosis

Sestrin2 is involved in different kind of cellular response to stress conditions. However, the function of Sestrin2 in oxidative stress related neurological diseases remains unknown. In this study, we tested whether Sestrin2 has a beneficial effect on PC12 cell apoptosis induced by H₂O₂. We found that H₂O₂ induces expression of Sestrin2 in PC12 cells in a time-dependent and dose-dependent manner. We also found that Knockdown of Sestrin2 using small RNA interference promotes cell apoptosis induced by H₂O₂. In addition, our results show that the c-Jun NH(2)-terminal kinase (JNK)/c-Jun pathway is activated by H₂O₂. Inhibiting the activity of the JNK pathway and JNK siRNA transfection abolishes the increase of Sestrin2 induced by H₂O₂. These findings suggest that the inductive effect of Sestrin2 is mediated by the JNK/c-Jun pathway. In this study, we investigated the role of Sestrin2 in oxidative stress-induced cell apoptosis using PC12 cells as the model, implying that stimulating expression of Sestrin2 might be considered as a neuroprotective target against H₂O₂-induced oxidative stress.

JNK1 ablation in mice confers long-term metabolic protection from diet-induced obesity at the cost of moderate skin oxidative damage

Obesity and insulin resistance are associated with oxidative stress, which may be implicated in the progression of obesity-related diseases. The kinase JNK1 has emerged as a promising drug target for the treatment of obesity and type 2 diabetes. JNK1 is also a key mediator of the oxidative stress response, which can promote cell death or survival, depending on the magnitude and context of its activation. In this article, we describe a study in which the long-term effects of JNK1 inactivation on glucose homeostasis and oxidative stress in obese mice were investigated for the first time. Mice lacking JNK1 (JNK1(-/-)) were fed an obesogenic high-fat diet (HFD) for a long period. JNK1(-/-) mice fed an HFD for the long term had reduced expression of antioxidant genes in their skin, more skin oxidative damage, and increased epidermal thickness and inflammation compared with the effects in control wild-type mice. However, we also observed that the protection from obesity, adipose tissue inflammation, steatosis, and insulin resistance, conferred by JNK1 ablation, was sustained over a long period and was paralleled by decreased oxidative damage in fat and liver. We conclude that compounds targeting JNK1 activity in brain and adipose tissue, which do not accumulate in the skin, may be safer and most effective.-Becattini, B., Zani, F., Breasson, L., Sardi, C., D'Agostino, V. G., Choo, M.-K., Provenzani, A., Park, J. M., Solinas, G. JNK1 ablation in mice confers long-term metabolic protection from diet-induced obesity at the cost of moderate skin oxidative damage.

Molecular Changes in the Nasal Cavity after N, N-dimethyl-p-toluidine Exposure

N, N-dimethyl-p-toluidine (DMPT; Cas No. 99-97-8), an accelerant for methyl methacrylate monomers in medical devices, is a nasal cavity carcinogen according to a 2-yr cancer study of male and female F344/N rats, with the nasal tumors arising from the transitional cell epithelium. In this study, we exposed male F344/N rats for 5 days to DMPT (0, 1, 6, 20, 60, or 120 mg/kg [oral gavage]) to explore the early changes in the nasal cavity after short-term exposure. Lesions occurred in the nasal cavity including hyperplasia of transitional cell epithelium (60 and 120 mg/kg). Nasal tissue was rapidly removed and preserved for subsequent laser capture microdissection and isolation of the transitional cell epithelium (0 and 120 mg/kg) for transcriptomic studies. DMPT transitional cell epithelium gene transcript patterns were characteristic of an antioxidative damage response (e.g., Akr7a3, Maff, and Mgst3), cell proliferation, and decrease in signals for apoptosis. The transcripts of amino acid transporters were upregulated (e.g., Slc7a11). The DMPT nasal transcript expression pattern was similar to that found in the rat nasal cavity after formaldehyde exposure, with over 1,000 transcripts in common. Molecular changes in the nasal cavity after DMPT exposure suggest that oxidative damage is a mechanism of the DMPT toxic and/or carcinogenic effects.

Upregulation of Sestrin2 expression protects against macrophage apoptosis induced by oxidized low-density lipoprotein

Sestrin2 is involved in a different cellular response to stress conditions. However, the function of Sestrin2 in the cardiovascular system remains unknown. In the present study, we tested whether Sestrin2 has a beneficial effect on macrophage cell apoptosis induced by oxidized low-density lipoprotein (oxLDL). We found that oxLDL induces expression of Sestrin2 in RAW264.7 cells in a time-dependent and dose-dependent manner. We also found that knockdown of Sestrin2 using small RNA interference promotes cell apoptosis and reactive oxygen species production induced by oxLDL. In addition, our results show that the c-Jun NH(2)-terminal kinase (JNK)/c-Jun pathway is activated by oxLDL. Inhibiting the activity of the JNK pathway abolishes the increase of Sestrin2 induced by oxLDL. These findings suggest that the inductive effect of Sestrin2 is mediated by the JNK/c-Jun pathway. Our results indicate that the induction of Sestrin2 acts as a compensatory response to oxLDL for survival, implying that stimulating expression of Sestrin2 might be an effective pharmacological target for the treatment of lipid-related cardiovascular diseases.