MiR-370 accelerated cerebral ischemia reperfusion injury via targeting SIRT6 and regulating Nrf2/ARE signal pathway

Neuroprotective potential for mitigating ischemia-reperfusion-induced damage

Reperfusion following cerebral ischemia causes both structural and functional damage to brain tissue and could aggravate a patient's condition; this phenomenon is known as cerebral ischemia-reperfusion injury. Current studies have elucidated the neuroprotective role of the sirtuin protein family (Sirtuins) in modulating cerebral ischemia-reperfusion injury. However, the potential of utilizing it as a novel intervention target to influence the prognosis of cerebral ischemia-reperfusion injury requires additional exploration. In this review, the origin and research progress of Sirtuins are summarized, suggesting the involvement of Sirtuins in diverse mechanisms that affect cerebral ischemia-reperfusion injury, including inflammation, oxidative stress, blood-brain barrier damage, apoptosis, pyroptosis, and autophagy. The therapeutic avenues related to Sirtuins that may improve the prognosis of cerebral ischemia-reperfusion injury were also investigated by modulating Sirtuins expression and affecting representative pathways, such as nuclear factor-kappa B signaling, oxidative stress mediated by adenosine monophosphate-activated protein kinase, and the forkhead box O. This review also summarizes the potential of endogenous substances, such as RNA and hormones, drugs, dietary supplements, and emerging therapies that regulate Sirtuins expression. This review also reveals that regulating Sirtuins mitigates cerebral ischemia-reperfusion injury when combined with other risk factors. While Sirtuins show promise as a potential target for the treatment of cerebral ischemia-reperfusion injury, most recent studies are based on rodent models with circadian rhythms that are distinct from those of humans, potentially influencing the efficacy of Sirtuins-targeting drug therapies. Overall, this review provides new insights into the role of Sirtuins in the pathology and treatment of cerebral ischemia-reperfusion injury.

Baicalein Inhibits Cerebral Ischemia-Reperfusion Injury through SIRT6-Mediated FOXA2 Deacetylation to Promote SLC7A11 Expression

Ischemic stroke (IS) poses a serious threat to patient survival. The inhibition of ferroptosis can effectively alleviate ischemia-reperfusion (I/R) injury, suggesting potential targets in the ferroptosis pathway for the treatment of IS. In this study, MCAO/R mice and OGD/R-induced HT22 cell were constructed. It was found that baicalein decreased ROS, MDA, and Fe2+ levels, upregulated GSH levels, and enhanced the expression of ferroptosis-related proteins (GPX4 and SLC7A11), downregulated the expression of proapoptotic proteins (Bax, cytochrome c, and cleaved caspase-3), and upregulated the expression of an antiapoptotic protein (Bcl-2), ameliorating cerebral I/R injury. In animal and cell models, Sirtuin6 (SIRT6) is downregulated, and Forkhead boxA2 (FOXA2) expression and acetylation levels are abnormally upregulated. SIRT6 inhibited FOXA2 expression and acetylation. Baicalein promoted FOXA2 deacetylation by upregulating SIRT6 expression. FOXA2 transcriptionally inhibits SLC7A11 expression. In conclusion, baicalein inhibited apoptosis and partially suppressed the role of ferroptosis to alleviate cerebral I/R injury via SIRT6-mediated FOXA2 deacetylation to promote SLC7A11 expression.

Correlation of potential diagnostic biomarkers (circulating miRNA and protein) of bipolar II disorder

OBJECTIVES

We previously identified certain peripheral biomarkers of bipolar II disorder (BD-II) including circulating miRNAs (miR-7-5p, miR-142-3p, miR-221-5p, and miR-370-3p) and proteins (Matrix metallopeptidase 9 (MMP9), phenylalanyl-tRNA synthetase subunit beta (FARSB), peroxiredoxin 2 (PRDX2), carbonic anhydrase 1 (CA-1), and proprotein convertase subtilisin/kexin type 9 (PCSK9)). We try to explore the connection between these biomarkers.

METHODS

We explored correlations between the peripheral levels of above circulating miRNAs and proteins in our previously collected BD-II (N = 96) patients and control (N = 115) groups. We further searched TargetScan and BioGrid websites to identify direct and indirect interactions between these protein-coding genes and circulating miRNAs.

RESULTS

In the BD-II group, we identified significant correlations between the miR-221-5p and CA-1 (rho = -0.323, P = 0.001), FARSB (rho = 0.251, P = 0.014), MMP-9 (rho = 0.313, P = 0.002) and PCSK9 (rho = 0.252, P = 0.014). The miR-370-3p also significantly correlated with FARSB expression (rho = 0.330, P = 0.001) and PCSK9 expression (rho = 0.221, P = 0.031) in the BD-II group. Our findings were in line with the modulating axis identified from TargetScan and BioGrid, miR-221-5p/CA-1/MMP9 and miR-370-3p/FARSB/PCSK9, suggesting their association with BD-II.

CONCLUSION

Our result supported that peripheral candidate miRNA and protein biomarkers may interact in BD-II. We concluded that miR-221-5p/CA-1/MMP9 and miR-370-3p/FARSB/PCSK9 axes might act a critical role in the pathomechanism of BD-II.

Neuronal Responses to Ischemia: Scoping Review of Insights from Human-Derived In Vitro Models

Translation of neuroprotective treatment effects from experimental animal models to patients with cerebral ischemia has been challenging. Since pathophysiological processes may vary across species, an experimental model to clarify human-specific neuronal pathomechanisms may help. We conducted a scoping review of the literature on human neuronal in vitro models that have been used to study neuronal responses to ischemia or hypoxia, the parts of the pathophysiological cascade that have been investigated in those models, and evidence on effects of interventions. We included 147 studies on four different human neuronal models. The majority of the studies (132/147) was conducted in SH-SY5Y cells, which is a cancerous cell line derived from a single neuroblastoma patient. Of these, 119/132 used undifferentiated SH-SY5Y cells, that lack many neuronal characteristics. Two studies used healthy human induced pluripotent stem cell derived neuronal networks. Most studies used microscopic measures and established hypoxia induced cell death, oxidative stress, or inflammation. Only one study investigated the effect of hypoxia on neuronal network functionality using micro-electrode arrays. Treatment targets included oxidative stress, inflammation, cell death, and neuronal network stimulation. We discuss (dis)advantages of the various model systems and propose future perspectives for research into human neuronal responses to ischemia or hypoxia.

The Role of microRNAs in Epigenetic Regulation of Signaling Pathways in Neurological Pathologies

In recent times, there has been a significant increase in researchers' interest in the functions of microRNAs and the role of these molecules in the pathogenesis of many multifactorial diseases. This is related to the diagnostic and prognostic potential of microRNA expression levels as well as the prospects of using it in personalized targeted therapy. This review of the literature analyzes existing scientific data on the involvement of microRNAs in the molecular and cellular mechanisms underlying the development of pathologies such as Alzheimer's disease, cerebral ischemia and reperfusion injury, and dysfunction of the blood-brain barrier.

Sirtuins: Promising Therapeutic Targets to Treat Ischemic Stroke

Stroke is a major cause of mortality and disability globally, with ischemic stroke (IS) accounting for over 80% of all stroke cases. The pathological process of IS involves numerous signal molecules, among which are the highly conserved nicotinamide adenine dinucleotide (NAD+)-dependent enzymes known as sirtuins (SIRTs). SIRTs modulate various biological processes, including cell differentiation, energy metabolism, DNA repair, inflammation, and oxidative stress. Importantly, several studies have reported a correlation between SIRTs and IS. This review introduces the general aspects of SIRTs, including their distribution, subcellular location, enzyme activity, and substrate. We also discuss their regulatory roles and potential mechanisms in IS. Finally, we describe the current therapeutic methods based on SIRTs, such as pharmacotherapy, non-pharmacological therapeutic/rehabilitative interventions, epigenetic regulators, potential molecules, and stem cell-derived exosome therapy. The data collected in this study will potentially contribute to both clinical and fundamental research on SIRTs, geared towards developing effective therapeutic candidates for future treatment of IS.

The role of mammalian Sirtuin 6 in cardiovascular diseases and diabetes mellitus

Cardiovascular diseases are severe diseases posing threat to human health because of their high morbidity and mortality worldwide. The incidence of diabetes mellitus is also increasing rapidly. Various signaling molecules are involved in the pathogenesis of cardiovascular diseases and diabetes. Sirtuin 6 (Sirt6), which is a class III histone deacetylase, has attracted numerous attentions since its discovery. Sirt6 enjoys a unique structure, important biological functions, and is involved in multiple cellular processes such as stress response, mitochondrial biogenesis, transcription, insulin resistance, inflammatory response, chromatin silencing, and apoptosis. Sirt6 also plays significant roles in regulating several cardiovascular diseases including atherosclerosis, coronary heart disease, as well as cardiac remodeling, bringing Sirt6 into the focus of clinical interests. In this review, we examine the recent advances in understanding the mechanistic working through which Sirt6 alters the course of lethal cardiovascular diseases and diabetes mellitus.

Transcutaneous Electrical Acupoint Stimulation Pretreatment Alleviates Cerebral Ischemia-Reperfusion Injury in Rats by Modulating Microglia Polarization and Neuroinflammation Through Nrf2/HO-1 Signaling Pathway

Cerebral ischemia-reperfusion injury (CIRI) may lead to severe disability even death, but the strategies for prevention and treatment are still limited. Transcutaneous electrical acupoint stimulation (TEAS) has been reported to have a significant neuroprotection against CIRI, but the underlying mechanisms remain obscure. In this study, we established a focal cerebral ischemia-reperfusion model in male Sprague-Dawley rats. TEAS pretreatment was applied to Baihui (GV20), Sanyinjiao (SP6) and Zusanli (ST36) acupoints for 5 consecutive days before CIRI. After 24 h reperfusion, the brain damage was assessed using Zea-Longa score, brain water content (BWC) and infarct volume. Meanwhile, the number of activated microglia and the TNF-α were detected by immunofluorescence and ELISA respectively. Moreover, Western Blot and RT-qPCR were conducted to detect the proteins and mRNA expressions of Nrf2, HO-1, iNOS and Arg-1. We found that TEAS pretreatment significantly reduced Longa score, BWC, infarct volume and the number of activated microglia. Besides, TEAS pretreatment increased Nrf2 and HO-1 levels, while lowered the expression of TNF-α. Subsequently, we also discovered that the microglia M1 phenotype maker iNOS decreased and the M2 maker Arg-1 increased after TEAS pretreatment. However, these effects of TEAS pretreatment were markedly eliminated by brusatol. These findings clearly suggested that TEAS pretreatment exerted neuroprotection against CIRI, which might be related to modulating microglia polarization and neuroinflammation via Nrf2/HO-1 pathway.

SIRT6 in Aging, Metabolism, Inflammation and Cardiovascular Diseases

As an important NAD⁺-dependent enzyme, SIRT6 has received significant attention since its discovery. In view of observations that SIRT6-deficient animals exhibit genomic instability and metabolic disorders and undergo early death, SIRT6 has long been considered a protein of longevity. Recently, growing evidence has demonstrated that SIRT6 functions as a deacetylase, mono-ADP-ribosyltransferase and long fatty deacylase and participates in a variety of cellular signaling pathways from DNA damage repair in the early stage to disease progression. In this review, we elaborate on the specific substrates and molecular mechanisms of SIRT6 in various physiological and pathological processes in detail, emphasizing its links to aging (genomic damage, telomere integrity, DNA repair), metabolism (glycolysis, gluconeogenesis, insulin secretion and lipid synthesis, lipolysis, thermogenesis), inflammation and cardiovascular diseases (atherosclerosis, cardiac hypertrophy, heart failure, ischemia-reperfusion injury). In addition, the most recent advances regarding SIRT6 modulators (agonists and inhibitors) as potential therapeutic agents for SIRT6-mediated diseases are reviewed.

Targeting Nrf2 in ischemia-reperfusion alleviation: From signaling networks to therapeutic targeting

The nuclear factor erythroid 2-related factor 2 (Nrf2) is a master regulator of redox balance and it responds to various cell stresses that oxidative stress is the most well-known one. The Nrf2 should undergo nuclear translocation to exert its protective impacts and decrease ROS production. On the other hand, ischemic/reperfusion (I/R) injury is a pathological event resulting from low blood flow to an organ and followed by reperfusion. The I/R induces cell injury and organ dysfunction. The present review focuses on Nrf2 function in alleviation of I/R injury. Stimulating of Nrf2 signaling ameliorates I/R injury in various organs including lung, liver, brain, testis and heart. The Nrf2 enhances activity of antioxidant enzymes to reduce ROS production and prevent oxidative stress-mediated cell death. Besides, Nrf2 reduces inflammation via decreasing levels of pro-inflammatory factors including IL-6, IL-1β and TNF-α. Nrf2 signaling is beneficial in preventing apoptosis and increasing cell viability. Nrf2 induces autophagy to prevent apoptosis during I/R injury. Furthermore, it can interact with other molecular pathways including PI3K/Akt, NF-κB, miRNAs, lncRNAs and GSK-3β among others, to ameliorate I/R injury. The therapeutic agents, most of them are phytochemicals such as resveratrol, berberine and curcumin, induce Nrf2 signaling in I/R injury alleviation.

Circ_TLK1 knockdown alleviates oxygen-glucose deprivation/reoxygenation-induced PC12 cell injury by regulating microRNA-136-5p/follistatin like-1 axis

BACKGROUND

Circular RNAs (circRNAs) are aberrantly expressed in the central nervous system (CNS) and are involved in diverse CNS diseases. However, the functions of circRNAs in ischemic stroke (IS) are largely unknown. In this study, we aimed to explore the effect of circ_TLK1 in oxygen-glucose deprivation/reoxygenation (OGD/R)-induced PC12 cell injury.

METHODS

Quantitative real-time polymerase chain reaction (qRT-PCR) was performed for the levels of circ_TLK1, TLK1, microRNA-136-5p (miR-136-5p), and follistatin like-1 (FSTL1). RNase R and Actinomycin D assays were conducted to analyze the features of circ_TLK1. 3-(4, 5-ethynyl-2'-deoxyuridine [EdU] assay and 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide (MTT) assay were adopted to analyze cell proliferation capacity. Flow cytometry analysis was applied to determine cell death. Western blot assay was employed to measure protein levels. The release of lactate dehydrogenase (LDH) was measured with specific kits. The interaction between circ_TLK1 and miR-136-5p, as well as miR-136-5p and FSTL1, was verified by Dual-luciferase reporter assay.

RESULTS

Circ_TLK1 was upregulated in OGD/R-injured PC12 cells. OGD/R treatment inhibited cell proliferation, promoted cell death, and increased LDH release in PC12 cells, while circ_TLK1 knockdown partially alleviated OGD/R-induced PC12 cell injury. Circ_TLK1 directly bound to miR-136-5p and miR-136-5p inhibition reversed the effect of circ_TLK1 knockdown on OGD/R-induced PC12 cell damage. Moreover, FSTL1 was targeted by miR-136-5p. MiR-136-5p upregulation inhibited PC12 cell injury induced by OGD/R, while FSTL1 overexpression partially reversed the effect.

CONCLUSION

Circ_TLK1 knockdown ameliorated OGD/R-induced PC12 cell injury by modulating miR-136-5p and FSTL1, which might provide a new understanding of IS treatment.

SIRT6 mediates multidimensional modulation to maintain organism homeostasis

As a member of the silent information regulators (sirtuins) family, SIRT6 can regulate a variety of biological processes, including DNA repair, glucose and lipid metabolism, oxidative stress and lifespan, and so forth. SIRT6 maintains organism homeostasis in a variety of phenotypes by mediating epigenetic regulation and posttranslational modification of functional proteins. In this review, we outline the structural basis of SIRT6 enzyme activity and its mechanism of maintaining organism homeostasis in a variety of phenotypes, with an emphasis on the upstream that regulates SIRT6 expression and the downstream substrates. And how SIRT6 achieves multidimensional coordination to maintain organism homeostasis and even extend lifespan. We try to understand the regulatory mechanism of SIRT6 in different phenotypes from the perspective of protein interaction.

Mechanism of lncRNA SNHG16 in oxidative stress and inflammation in oxygen-glucose deprivation and reoxygenation-induced SK-N-SH cells

Cerebral ischemia-reperfusion injury imposes a clinical challenge for physicians in the wake of ischemic stroke. Meanwhile, recent evidence has come to light eliciting the neuroprotective function of SNHG16 in cerebrovascular diseases. Accordingly, the current study sought to analyze the regulatory mechanism of long non-coding RNA small nucleolar RNA host gene16 (SNHG16) in oxidative stress (OS) injury and cell inflammation. Firstly, models of oxygen-glucose deprivation and reoxygenation (OGD/R) were established in SK-N-SH cells. Cell proliferation and apoptosis were appraised using cell counting kit-8 and flow cytometry. Additionally, SNHG16, X-linked inhibitor of apoptosis protein (XIAP), microRNA (miR-421), reactive oxygen species (ROS), lactate dehydrogenase (LDH), malondialdehyde (MDA), superoxide dismutase (SOD), tumor necrosis factor -α, interleukin (IL)-1β, and IL-10 expression patterns were determined. In addition, we determined and validated the subcellular localization of SNHG16 and the binding relationships between SNHG16 and miR-421, and miR-421 and XIAP. It was found that SNHG16 was poorly-expressed in OGD/R-treated cells. On the other hand, SNHG16 over-expression enhanced cell proliferation, inhibited apoptosis, and alleviated OS and cell inflammation. Furthermore, SNHG16 bound to miR-421 to facilitate the expression of XIAP. Up-regulation of miR-421 or down-regulation of XIAP could reverse the suppressive effects of SNHG16 on OS and cell inflammation. Collectively, our findings indicated that SNHG16 bound to miR-421 to facilitate XIAP expression, thus alleviating OS injury and inflammation in OGD/R-induced SK-N-SH cells.

USP10 alleviates sepsis-induced acute kidney injury by regulating Sirt6-mediated Nrf2/ARE signaling pathway

Background

Severe sepsis, a major health problem worldwide, has become one of the leading causes of death in ICU patients. Further study on the pathogenesis and treatment of acute kidney injury (AKI) is of great significance to reduce high mortality rate of sepsis. In this study, the mechanism by which ubiquitin specific peptidase 10 (USP10) reduces sepsis-induced AKI was investigated. Ligation and perforation of cecum (CLP) was employed to establish C57BL/6 mouse models of sepsis. Hematoxylin-eosin (H&E) staining was performed to detect renal injury. The concentrations of serum creatinine (Cr), urea nitrogen (BUN) and cystatin C (Cys C) were determined using a QuantiChrom™ Urea Assay kit. RT-qPCR and western blot were conducted to assess the USP10 expression level. DHE staining was used to detect reactive oxygen species (ROS) levels. H₂O₂, MDA and SOD levels were assessed using corresponding colorimetric kits. Western blot was used to examine the expression levels of Bcl-2, Bax, cleaved caspase-3, Sirt6, Nrf2 and HO-1. MTT assay was used to determine cell viability, whereas TUNEL staining and flow cytometry were used to assess cell apoptosis.

Results

In this study, we found that USP10 was decreased in CLP-induced mouse renal tissues. We identified that USP10 alleviated renal dysfunction induced by CLP. Moreover, USP10 was found to reduce oxidative stress, and abated LPS-induced renal tubular epithelial cell injury and apoptosis. Finally, we discovered that USP10 promoted activation of the NRF2/HO-1 pathway through SIRT6 and attenuated LPS-induced renal tubular epithelial cell injury.

Conclusions

This study found that USP10 activates the NRF2/ARE signaling through SIRT6. USP10 alleviates sepsis-induced renal dysfunction and reduces renal tubular epithelial cell apoptosis and oxidative stress.

Down-Regulation of miR-181a-5p Prevents Cerebral Ischemic Injury by Upregulating En2 and Activating Wnt/β-catenin Pathway

PURPOSE

Cerebral ischemic injury contributes to severe dysfunction of the brain, which triggers extremely high mortality and disability. The role of microRNA (miR)-181a-5p is documented in cerebral ischemic injury. Therefore, this study intended to further figure out the mechanism of miR-181a-5p in cerebral ischemic injury.

METHODS

miR-181a-5p expression in middle cerebral artery occlusion (MCAO) mouse model, oxygen-glucose-deprivation/reoxygenation (OGD/R) N2a cell model, and serum from acute ischemic injury (ACI) patients was evaluated using reverse transcription quantitative polymerase chain reaction (RT-qPCR). Gain- and loss-of-function assays were implemented in MCAO mice and OGD/R-induced N2a cells. In mice, the cerebral infarction area was assessed with 2,3,5-triphenyltetrazolium chloride staining, the number of damaged neurons by Nissl staining, and apoptosis by TdT-mediated dUTP-biotin nick end-labeling staining. Moreover, N2a cell apoptosis and proliferation were determined with flow cytometry or 5-ethynyl-2'-deoxyuridine staining, respectively. The expression of En2 and Wnt/β-catenin pathway-related factors was determined with RT-qPCR and Western blot analysis. The targeting relationship between miR-181a-5p and En2 was evaluated by dual luciferase reporter gene assay.

RESULTS

miR-181a-5p was highly expressed in serum of ACI patients, MCAO mice, and OGD/R-induced N2a cells. En2, lowly expressed in MCAO mice, was targeted by miR-181a-5p, and miR-181a-5p down-regulation activated the Wnt/β-catenin pathway. Furthermore, miR-181a-5p inhibition or En2 overexpression reduced cerebral infarction area, the number of damaged neurons, and apoptosis in MCAO mice, and also diminished apoptosis and accelerated proliferation of OGD/R-induced N2a cells.

CONCLUSION

miR-181a-5p suppression activated Wnt/β-catenin pathway and sequentially attenuated cerebral ischemic injury by targeting En2.

Emerging roles of SIRT6 in human diseases and its modulators

The biological functions of sirtuin 6 (SIRT6; e.g., deacetylation, defatty-acylation, and mono-ADP-ribosylation) play a pivotal role in regulating lifespan and several fundamental processes controlling aging such as DNA repair, gene expression, and telomeric maintenance. Over the past decades, the aberration of SIRT6 has been extensively observed in diverse life-threatening human diseases. In this comprehensive review, we summarize the critical roles of SIRT6 in the onset and progression of human diseases including cancer, inflammation, diabetes, steatohepatitis, arthritis, cardiovascular diseases, neurodegenerative diseases, viral infections, renal and corneal injuries, as well as the elucidation of the related signaling pathways. Moreover, we discuss the advances in the development of small molecule SIRT6 modulators including activators and inhibitors as well as their pharmacological profiles toward potential therapeutics for SIRT6-mediated diseases.