CTRP3 Activates the AMPK/SIRT1-PGC-1α Pathway to Protect Mitochondrial Biogenesis and Functions in Cerebral Ischemic Stroke

Systems genetics analysis of human body fat distribution genes identifies adipocyte processes

Excess abdominal fat is a sexually dimorphic risk factor for cardio-metabolic disease and is approximated by the waist-to-hip ratio adjusted for body mass index (WHRadjBMI). Whereas this trait is highly heritable, few causal genes are known. We aimed to identify novel drivers of WHRadjBMI using systems genetics. We used two independent cohorts of adipose tissue gene expression and constructed sex- and depot-specific Bayesian networks to model gene-gene interactions from 8,492 genes. Using key driver analysis, we identified genes that, in silico and putatively in vitro, regulate many others. 51-119 key drivers in each network were replicated in both cohorts. In other cell types, 23 of these genes are found in crucial adipocyte pathways: Wnt signaling or mitochondrial function. We overexpressed or down-regulated seven key driver genes in human subcutaneous pre-adipocytes. Key driver genes ANAPC2 and RSPO1 inhibited adipogenesis, whereas PSME3 increased adipogenesis. RSPO1 increased Wnt signaling activity. In differentiated adipocytes, MIGA1 and UBR1 down-regulation led to mitochondrial dysfunction. These five genes regulate adipocyte function, and we hypothesize that they regulate fat distribution.

Mitochondrial mechanisms in Cerebral Ischemia-Reperfusion Injury: Unravelling the intricacies

Cerebral ischemic stroke is a major contributor to physical impairments and premature death worldwide. The available reperfusion therapies for stroke in the form of mechanical thrombectomy and intravenous thrombolysis increase the risk of cerebral ischemia-reperfusion (I-R) injury due to sudden restoration of blood supply to the ischemic region. The injury is manifested by hemorrhagic transformation, worsening of neurological impairments, cerebral edema, and progression to infarction in surviving patients. A complex network of multiple pathological processes has been known to be involved in the pathogenesis of I-R injury. Primarily, 3 major contributors namely oxidative stress, neuroinflammation, and mitochondrial failure have been well studied in I-R injury. A transcription factor, Nrf2 (Nuclear factor erythroid 2-related factor 2) plays a crucial defensive role in resisting the deleterious effects of I-R injury and potentiating the cellular protective mechanisms. In this review, we delve into the critical function of mitochondria and Nrf2 in the context of cerebral I-R injury. We summarized how oxidative stress, neuroinflammation, and mitochondrial anomaly contribute to the pathophysiology of I-R injury and further elaborated the role of Nrf2 as a pivotal guardian of cellular integrity. The review further highlighted Nrf2 as a putative therapeutic target for mitochondrial dysfunction in cerebral I-R injury management.

Exploring the intricacies of calcium dysregulation in ischemic stroke: Insights into neuronal cell death and therapeutic strategies

Calcium ion (Ca2+) dysregulation is one of the main causes of neuronal cell death and brain damage after cerebral ischemia. During ischemic stroke, the ability of neurons to maintain Ca2+ homeostasis is compromised. Ca2+ regulates various functions of the nervous system, including neuronal activity and adenosine triphosphate (ATP) production. Disruptions in Ca2+ homeostasis can trigger a cascade of events, including activation of the unfolded protein response (UPR) pathway, which is associated with endoplasmic reticulum (ER) stress and mitochondrial dysfunction. This response occurs when the cell is unable to manage protein folding within the ER due to various stressors, such as a high influx of Ca2+. Consequently, the UPR is initiated to restore ER function and alleviate stress, but prolonged activation can lead to mitochondrial dysfunction and, ultimately, cell death. Hence, precise regulation of Ca2+ within the cell is mandatory. The ER and mitochondria are two such organelles that maintain intracellular Ca2+ homeostasis through various calcium-operating channels, including ryanodine receptors (RyRs), inositol trisphosphate receptors (IP3Rs), sarco/endoplasmic reticulum calcium ATPases (SERCAs), the mitochondrial Na+/Ca2+ exchanger (NCLX), the mitochondrial calcium uniporter (MCU) and voltage-dependent anion channels (VDACs). These channels utilize Ca2+ sequestering and release mechanisms to maintain intracellular Ca2+ homeostasis and ensure proper cellular function and survival. The present review critically evaluates the significance of Ca2+ and its physiological role in cerebral ischemia. We have compiled recent findings on calcium's role and emerging treatment strategies, particularly targeting mitochondria and the endoplasmic reticulum, to address Ca2+ overload in cerebral ischemia.

Deciphering mitochondrial dysfunction: Pathophysiological mechanisms in vascular cognitive impairment

Vascular cognitive impairment (VCI) encompasses a range of cognitive deficits arising from vascular pathology. The pathophysiological mechanisms underlying VCI remain incompletely understood; however, chronic cerebral hypoperfusion (CCH) is widely acknowledged as a principal pathological contributor. Mitochondria, crucial for cellular energy production and intracellular signaling, can lead to numerous neurological impairments when dysfunctional. Recent evidence indicates that mitochondrial dysfunction-marked by oxidative stress, disturbed calcium homeostasis, compromised mitophagy, and anomalies in mitochondrial dynamics-plays a pivotal role in VCI pathogenesis. This review offers a detailed examination of the latest insights into mitochondrial dysfunction within the VCI context, focusing on both the origins and consequences of compromised mitochondrial health. It aims to lay a robust scientific groundwork for guiding the development and refinement of mitochondrial-targeted interventions for VCI.

Unveiling the interplay of AMPK/SIRT1/PGC-1α axis in brain health: Promising targets against aging and NDDs

The escalating prevalence of neurodegenerative diseases (NDDs) within an aging global population presents a pressing challenge. The multifaceted pathophysiological mechanisms underlying these disorders, including oxidative stress, mitochondrial dysfunction, and neuroinflammation, remain complex and elusive. Among these, the AMPK/SIRT1/PGC-1α pathway emerges as a pivotal network implicated in neuroprotection against these destructive processes. This review sheds light on the potential therapeutic implications of targeting this axis, specifically emphasizing the promising role of flavonoids in mitigating NDD-related complications. Expanding beyond conventional pharmacological approaches, the exploration of non-pharmacological interventions such as exercise and calorie restriction (CR), coupled with the investigation of natural compounds, offers a beacon of hope. By strategically elucidating the intricate connections within these pathways, this review aims to pave the ways for novel multi-target agents and interventions, fostering a renewed optimism in the quest to combat and manage the debilitating impacts of NDDs on global health and well-being.

Neuroprotective effect of, a flavonoid, sudachitin in mice stroke model

A flavonoid, sudachitin, has been reported to show some beneficial health effects, including as an anti-inflammatory in LPS-stimulated macrophages, as well as improving glucose and lipid metabolism in mice fed a high-fat diet. In this study, we investigated the neuroprotective effect of sudachitin in the transient middle cerebral artery occlusion (tMCAO) mouse model. After daily pre-treatment of vehicle or sudachitin (5 or 50 mg/kg) for 14 days, mice (n = 76) were subjected to a sham operation or tMCAO for 45 min, and on the following days, they were treated daily with vehicle or sudachitin. The administration of sudachitin significantly reduced (p < 0.05) cerebral infarct volume and attenuated apoptosis, 5 days after tMCAO. Neurological impairment improved, the expression of an oxidative stress marker, 4-HNE, decreased, and the Sirt1/PGC-1α pathway was activated 5 days after tMCAO in the sudachitin-treated group. This is the first report to demonstrate the neuroprotective effect of sudachitin in cerebral ischemia/reperfusion injury mice model, probably by activating the Sirt1/PGC-1α axis. Sudachitin may be a promising supplement or therapeutic agent for reducing injury caused by ischemic strokes.

Association between plasma CTRPs with cognitive impairment and neurodegeneration of Alzheimer's disease

AIMS

Recent evidence indicated the biological basis of complement 1q (C1q)/tumor necrosis factor (TNF)-related protein (CTRP) 3, 4, and 14 for affecting brain structure and cognitive function. Thus, we aimed to investigate the association between plasma CTRPs with Alzheimer's disease (AD).

METHODS

A multicenter, cross-sectional study recruited patients with AD (n = 137) and cognitively normal (CN) controls (n = 140). After the data collection of demographic characteristics, lifestyle risk factors, and medical history, plasma levels of tau phosphorylated at threonine 217 (pT217), pT181, neurofilament light (NfL), CTRP3, 4, and 14 were examined and compared. Multivariate logistic regression analysis was applied to determine associations of plasma CTPRs with the presence of AD. The correlation analysis was used to explore correlations between plasma CTPRs with scores of Mini-Mental State Examination (MMSE), Montreal Cognitive Assessment (MoCA), Activities of Daily Living (ADL) scale, and Clinical Dementia Rating Sum of Boxes (CDR-SB), and levels of plasma pT217, pT181, and NfL. Receiver-operating characteristic (ROC) analysis and Delong's test were used to determine the diagnostic power of plasma CTPRs.

RESULTS

Plasma levels of CTRP3, 4, and 14 were higher in AD group than those in CN group. After adjusting for conventional risk factors, CTRP3, CTRP4, and CTRP14 were associated with the presence of AD. In AD patients, CTRP3 was negatively correlated with scores of MMSE and MoCA, while positively correlated with ADL score, CDR-SB score, pT217, and pT181; CTRP4 was positively correlated with CDR-SB score, pT181, and NfL; CTRP14 was negatively correlated with MMSE score, while positively correlated with CDR-SB score, pT217, and NfL. An independent addition of CTRP3 and 4 to the basic model combining age, sex, years of education, APOE4 status, BMI, TG, and HDL-C led to a significant improvement in diagnostic power for AD, respectively.

CONCLUSIONS

All the findings preliminarily uncovered associations between plasma CTRPs and AD and suggested the potential of CTRPs as a blood-derived biomarker for AD.

CTRP3 alleviates mitochondrial dysfunction and oxidative stress injury in pathological cardiac hypertrophy by activating UPRmt via the SIRT1/ATF5 axis

Pathological cardiac hypertrophy is an independent risk factor for heart failure. Disruption of mitochondrial protein homeostasis plays a key role in pathological cardiac hypertrophy; however, the mechanism of maintaining mitochondrial homeostasis in pathological cardiac hypertrophy remains unclear. In this study, we investigated the regulatory mechanisms of mitochondrial protein homeostasis in pathological cardiac hypertrophy. Wildtype (WT) mice, knockout mice, and mice transfected with lentivirus overexpressing mouse C1q-tumor necrosis factor-related protein-3 (CTRP3) underwent transverse aortic constriction or sham surgery. After 4 weeks, cardiac function, mitochondrial function, and oxidative stress injury were examined. For mechanistic studies, neonatal rat cardiomyocytes were treated with small interfering RNA or overexpression plasmids for the relevant genes. CTRP3 overexpression attenuated transverse aortic constriction (TAC) induced pathological cardiac hypertrophy, mitochondrial dysfunction, and oxidative stress injury compared to that in WT mice. TAC or Ang II resulted in compensatory activation of UPRmt, but this was not sufficient to counteract pathologic cardiac hypertrophy. CTRP3 overexpression further induced activation of UPRmt during pathologic cardiac hypertrophy and thereby alleviated pathologic cardiac hypertrophy, whereas CTRP3 knockout or knockdown inhibited UPRmt. ATF5 was a key regulatory molecule of UPRmt, as ATF5 knockout prevented the cardioprotective effect of CTRP3 in TAC mice. In vitro, SIRT1 was identified as a possible downstream CTRP3 effector molecule, and SIRT1 knockout blocked the cardioprotective effects of CTRP3. Our results also suggest that ATF5 may be regulated by SIRT1. Our study demonstrates that CTRP3 activates UPRmt via the SIRT1/ATF5 axis under pathological myocardial hypertrophy, thus attenuating mitochondrial dysfunction and oxidative stress injury.

Systems genetics analysis of human body fat distribution genes identifies Wnt signaling and mitochondrial activity in adipocytes

BACKGROUND

Excess fat in the abdomen is a sexually dimorphic risk factor for cardio-metabolic disease. The relative storage between abdominal and lower-body subcutaneous adipose tissue depots is approximated by the waist-to-hip ratio adjusted for body mass index (WHRadjBMI). Genome-wide association studies (GWAS) identified 346 loci near 495 genes associated with WHRadjBMI. Most of these genes have unknown roles in fat distribution, but many are expressed and putatively act in adipose tissue. We aimed to identify novel sex- and depot-specific drivers of WHRadjBMI using a systems genetics approach.

METHODS

We used two independent cohorts of adipose tissue gene expression with 362 - 444 males and 147 - 219 females, primarily of European ancestry. We constructed sex- and depot- specific Bayesian networks to model the gene-gene interactions from 8,492 adipose tissue genes. Key driver analysis identified genes that, in silico and putatively in vitro, regulate many others, including the 495 WHRadjBMI GWAS genes. Key driver gene function was determined by perturbing their expression in human subcutaneous pre-adipocytes using lenti-virus or siRNA.

RESULTS

51 - 119 key drivers in each network were replicated in both cohorts. We used single-cell expression data to select replicated key drivers expressed in adipocyte precursors and mature adipocytes, prioritized genes which have not been previously studied in adipose tissue, and used public human and mouse data to nominate 53 novel key driver genes (10 - 21 from each network) that may regulate fat distribution by altering adipocyte function. In other cell types, 23 of these genes are found in crucial adipocyte pathways: Wnt signaling or mitochondrial function. We selected seven genes whose expression is highly correlated with WHRadjBMI to further study their effects on adipogenesis/Wnt signaling (ANAPC2, PSME3, RSPO1, TYRO3) or mitochondrial function (C1QTNF3, MIGA1, PSME3, UBR1).Adipogenesis was inhibited in cells overexpressing ANAPC2 and RSPO1 compared to controls. RSPO1 results are consistent with a positive correlation between gene expression in the subcutaneous depot and WHRadjBMI, therefore lower relative storage in the subcutaneous depot. RSPO1 inhibited adipogenesis by increasing β-catenin activation and Wnt-related transcription, thus repressing PPARG and CEBPA. PSME3 overexpression led to more adipogenesis than controls. In differentiated adipocytes, MIGA1 and UBR1 downregulation led to mitochondrial dysfunction, with lower oxygen consumption than controls; MIGA1 knockdown also lowered UCP1 expression.

SUMMARY

ANAPC2, MIGA1, PSME3, RSPO1, and UBR1 affect adipocyte function and may drive body fat distribution.

CTRP3 attenuates inflammation, oxidative and cell death in cisplatin induced HK-2 cells

Cisplatin has been widely studied and found to be a highly effective anti-tumor drug. It has several side effects, including acute kidney injury (AKI). Cisplatin-induced AKI can be primarily attributed to oxidative stress, inflammation, and apoptosis. The CTRP3 adipokine is a new adipokine that exhibits antioxidant, anti-inflammatory, and antiapoptotic properties. Despite this, the role of CTRP3 in AKI remain unclear. In cisplatin-induced AKI models, our findings demonstrated that CTRP3 expression was decreased in human proximal tubule epithelial cells (HK-2). In the in vitro experiments, HK-2 cells were first transfected with an overexpression plasmid of CTRP3 (pcDNA-CTRP3) or a small interfering RNA for CTRP3 (si-CTRP3) and induced by cisplatin; and cell oxidative stress, inflammation, proliferation, and apoptosis were found to be present. Overexpressing CTRP3 inhibited oxidative stress through decreasing malondialdehyde (MDA) levels and increasing the activity of SOD and CAT. The mRNA levels of SOD1 and SOD2 were increased in response to CTRP3 overexpression. Additionally, CTRP3 decreased TNF-α and MCP-1 levels. Moreover, CTRP3 overexpression increased cisplatin-induced cell activity and decreased cell apoptosis, as indicated by the elevated numbers of EdU positive cells and decreased numbers of apoptotic cells. Consistent with these results, the overexpression of CTRP3 effectively elevated the mRNA levels of Bcl-2 and reduced the mRNA levels of Bax. In contrast, inhibition of CTRP3 expression by si-CTRP3 reversed the cisplatin-induced indices. Mechanistically, we found that the overexpression of CTRP3 can increase expression of Nrf2 and inhibit the activation of MAPK phosphorylation (ERK, JNK, and p38). Furthermore, inhibition of ERK, JNK and p38 activity eliminated aggravation of cisplatin-induced inflammation and apoptosis caused by CTRP3 knockdown. Additionally, the cisplatin-induced oxidative stress and activation of MAPK phosphorylation (ERK, JNK, and p38) in HK-2 cells were reversed by Nrf2 suppression by siRNA. Collectively, these results indicated that CTRP3 may identify as a novel target for AKI treatment and protect against cisplatin-induced AKI through the Nrf2/MAPK pathway.

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 Adipokines in the Pathogenesis of Psoriasis

Psoriasis is a chronic and immune-mediated skin condition characterized by pro-inflammatory cytokines and keratinocyte hyperproliferation. Dendritic cells, T lymphocytes, and keratinocytes represent the main cell subtypes involved in the pathogenesis of psoriasis, while the interleukin-23 (IL-23)/IL-17 pathway enhances the disease progression. Human adipose tissue is an endocrine organ, which secretes multiple proteins, known as adipokines, such as adiponectin, leptin, visfatin, or resistin. Current evidence highlights the immunomodulatory roles of adipokines, which may contribute to the progression or suppression of psoriasis. A better understanding of the complexity of psoriasis pathophysiology linked with adipokines could result in developing novel diagnostic or therapeutic strategies. This review aims to present the pathogenesis of psoriasis and the roles of adipokines in this process.

Stroke: Molecular mechanisms and therapies: Update on recent developments

Stroke, a neurological disease, is one of the leading causes of death worldwide, resulting in long-term disability in most survivors. Annual stroke costs in the United States alone were estimated at $46 billion recently. Stroke pathophysiology is complex, involving multiple causal factors, among which atherosclerosis, thrombus, and embolus are prevalent. The molecular mechanisms involved in the pathophysiology are essential to understanding targeted drug development. Some common mechanisms are excitotoxicity and calcium overload, oxidative stress, and neuroinflammation. In addition, various modifiable and non-modifiable risk factors increase the chances of stroke manifolds. Once a patient encounters a stroke, complete restoration of motor ability and cognitive skills is often rare. Therefore, shaping therapeutic strategies is paramount for finding a viable therapeutic agent. Apart from tPA, an FDA-approved therapy that is applied in most stroke cases, many other therapeutic strategies have been met with limited success. Stroke therapies often involve a combination of multiple strategies to restore the patient's normal function. Certain drugs like Gamma-aminobutyric receptor agonists (GABA), Glutamate Receptor inhibitors, Sodium, and Calcium channel blockers, and fibrinogen-depleting agents have shown promise in stroke treatment. Recently, a drug, DM199, a recombinant (synthetic) form of a naturally occurring protein called human tissue kallikrein-1 (KLK1), has shown great potential in treating stroke with fewer side effects. Furthermore, DM199 has been found to overcome the limitations presented when using tPA and/or mechanical thrombectomy. Cell-based therapies like Neural Stem Cells, Hematopoietic stem cells (HSCs), and Human umbilical cord blood-derived mesenchymal stem cells (HUCB-MSCs) are also being explored as a treatment of choice for stroke. These therapeutic agents come with merits and demerits, but continuous research and efforts are being made to develop the best therapeutic strategies to minimize the damage post-stroke and restore complete neurological function in stroke patients.

C1q/TNF-related protein-2 improved angiogenesis to protect myocardial function during ischaemia‒reperfusion

BACKGROUND

Collateral growth plays an important role in the recovery of acute myocardial infarction. C1q/TNF-related protein-2 (CTRP2), a CTRP family member, showed some protective effects on cell survival. In this study, the relationship between CTRP2 and collateral growth was examined.

METHODS

C57BL/6 mice were subjected to myocardial ischaemia/reperfusion (I/R), and the expression of CTRP2 and the effect of CTRP2 on infarction size, cardiac function and angiogenesis were examined. The ischaemic hindlimb model was also used to examine the effect of CTRP2. In vitro, CTRP2-mediated regulation of angiogenesis, AKT activation and VEGFR2 expression in endothelial cells was examined. The CTRP2 level associated with good collateral growth was observed in a cohort.

RESULTS

I/R reduced CTRP2 expression, and intraperitoneal injection of recombinant CTRP2 protein improved infarction size, cardiac function and angiogenesis. Overexpression of CTRP2 promoted blood refusion and collateral growth in ischaemic hindlimb mice. In vitro, CTRP2 enhanced tube formation and migration in a dose-dependent manner, while CTRP2 increased AKT phosphorylation and VEGFR2 expression. In an observational clinical cohort, CTRP2 levels were significantly increased in patients with good collateral growth, and CTRP2 was negatively associated with poor collateral growth in patients.

CONCLUSION

CTRP2 improved cardiac function by promoting collateral growth by promoting AKT-VEGFR2.

Circulating Levels of C1q/TNF-Related Protein 3 (CTRP3) and CTRP9 in Gestational Diabetes and Their Association with Insulin Resistance and Inflammatory Cytokines

Objective

Gestational diabetes mellitus (GDM) is closely related to obesity, adipose tissue, and adipokines. Adiponectin-homologous adipokines with anti-inflammatory properties, including C1q/TNF-related protein 3 (CTRP3) and CTRP9, regulate glucose and lipid metabolism, which was measured in pregnant women with GDM with the aim to assess their circulating levels and their relation with inflammatory cytokines and other biochemical data.

Methods

Serum levels of CTRP3, CTRP9, adiponectin, tumor necrosis factor (TNF)-α, and interleukin (IL)-6 were measured in 43 subjects with GDM and 42 healthy controls by enzyme-linked immunosorbent assay.

Results

Serum levels of adiponectin and CTRP3 were lower in GDM subjects than in controls, whereas CTRP9, TNF-α, and IL-6 showed higher concentrations in subjects with GDM than in controls. In the subjects with GDM, there was a significant association of CTRP3 with homeostasis model assessment of insulin resistance (HOMA-IR), body mass index, and triglycerides, whereas CTRP9 is associated with TNF-α and HOMA-IR.

Conclusion

The differences in the assessed levels of CTRP3 and CTRP9 suggest a possible relation with the pathogenesis of GDM, in particular insulin resistance, which showed significant association with both adipokines.

Role of NAD+ and FAD in Ischemic Stroke Pathophysiology: An Epigenetic Nexus and Expanding Therapeutic Repertoire

The redox coenzymes viz., oxidized β-nicotinamide adenine dinucleotide (NAD⁺) and flavin adenine dinucleotide (FAD) by way of generation of optimal reducing power and cellular energy currency (ATP), control a staggering array of metabolic reactions. The prominent cellular contenders for NAD⁺ utilization, inter alia, are sirtuins (SIRTs) and poly(ADP-ribose) polymerase (PARP-1), which have been significantly implicated in ischemic stroke (IS) pathogenesis. NAD⁺ and FAD are also two crucial epigenetic enzyme-required metabolites mediating histone deacetylation and poly(ADP-ribosyl)ation through SIRTs and PARP-1 respectively, and demethylation through FAD-mediated lysine specific demethylase activity. These enzymes and post-translational modifications impinge on the components of neurovascular unit, primarily neurons, and elicit diverse functional upshots in an ischemic brain. These could be circumstantially linked with attendant cognitive deficits and behavioral outcomes in post-stroke epoch. Parsing out the contribution of NAD⁺/FAD-synthesizing and utilizing enzymes towards epigenetic remodeling in IS setting, together with their cognitive and behavioral associations, combined with possible therapeutic implications will form the crux of this review.

Intermittent hypoxia promotes the recovery of motor function in rats with cerebral ischemia by regulating mitochondrial function

Hypoxia preconditioning is neuroprotective, but the therapeutic effects of intermittent hypoxia were not fully considered. The present study investigated the neuroprotective effect and mechanism of intermittent hypoxia on motor function after cerebral ischemia and explored alternative clinical treatment options. In total, 36 8-week-old male Sprague-Dawley rats were subjected to 60 min of transient middle cerebral artery occlusion (tMCAO) and then randomly divided into a sham-operated group (SHAM), tMCAO-sedentary group (SED), and tMCAO-intermittent hypoxia group (IH). The intervention was performed 1 week after tMCAO and lasted 4 weeks. Rats in the IH group were placed in an animal hypoxic chamber (altitude 5000 m and oxygen concentration of 13%) for 4 h/day and 7 days/week, and rats in the SED group were placed in a normoxic environment for 4 weeks. Body weights, neurological deficit scores, cerebral infarction volume ratios, gait analyses, mitochondrial structure, adenosine triphosphate (ATP) content and AMO-activated protein kinase (AMPK), peroxisome proliferator-activated receptor γ co-activator-1α (PGC-1α), and silencing regulatory protein 3 (Sirt3) expression in the peri-ischemic region brain tissues were detected during the intervention. Compared with the SED group, the body weight of the IH group gradually recovered, and the neurological deficit scores were significantly reduced (P < 0.05). The gait analysis results showed that the pressure of the affected paw and the maximum content area, swing speed, stride length, and other parameters were significantly restored (P < 0.05). The cerebral infarction volume ratio was significantly reduced (P < 0.01). Mitochondrial morphological structure damage in the peri-ischemic region brain tissues recovered, the number was significantly increased (P < 0.05), and the expression of AMPK, PGC-1α, and Sirt3 proteins (P < 0.05), and ATP content were significantly increased (P < 0.05). Intermittent hypoxia may activate the AMPK-PGC-1α-Sirt3 signaling pathway, promote mitochondrial biogenesis, repair mitochondrial ultrastructural damage, and improve mitochondrial function to reduce brain damage and promote motor function recovery in rats with cerebral ischemia.

Signaling pathways involved in ischemic stroke: molecular mechanisms and therapeutic interventions

Ischemic stroke is caused primarily by an interruption in cerebral blood flow, which induces severe neural injuries, and is one of the leading causes of death and disability worldwide. Thus, it is of great necessity to further detailly elucidate the mechanisms of ischemic stroke and find out new therapies against the disease. In recent years, efforts have been made to understand the pathophysiology of ischemic stroke, including cellular excitotoxicity, oxidative stress, cell death processes, and neuroinflammation. In the meantime, a plethora of signaling pathways, either detrimental or neuroprotective, are also highly involved in the forementioned pathophysiology. These pathways are closely intertwined and form a complex signaling network. Also, these signaling pathways reveal therapeutic potential, as targeting these signaling pathways could possibly serve as therapeutic approaches against ischemic stroke. In this review, we describe the signaling pathways involved in ischemic stroke and categorize them based on the pathophysiological processes they participate in. Therapeutic approaches targeting these signaling pathways, which are associated with the pathophysiology mentioned above, are also discussed. Meanwhile, clinical trials regarding ischemic stroke, which potentially target the pathophysiology and the signaling pathways involved, are summarized in details. Conclusively, this review elucidated potential molecular mechanisms and related signaling pathways underlying ischemic stroke, and summarize the therapeutic approaches targeted various pathophysiology, with particular reference to clinical trials and future prospects for treating ischemic stroke.

Puerarin Attenuates Oxidative Stress and Ferroptosis via AMPK/PGC1α/Nrf2 Pathway after Subarachnoid Hemorrhage in Rats

Puerarin was shown to exert anti-oxidative and anti-ferroptosis effects in multiple diseases. The goal of this study was to explore the neuroprotective effect of puerarin on early brain injury (EBI) after subarachnoid hemorrhage (SAH) in rats. A total of 177 adult male Sprague Dawley rats were used. SAH was included via endovascular perforation. Intranasal puerarin or intracerebroventricular dorsomorphin (AMPK inhibitor) and SR18292 (PGC1α inhibitor) were administered. The protein levels of pAMPK, PGC1α, Nrf2, 4HNE, HO1, MDA, ACSL4, GSSG, and iron concentration in the ipsilateral hemisphere were significantly increased, whereas SOD, GPX4, and GSH were decreased at 24 h after SAH. Moreover, puerarin treatment significantly increased the protein levels of pAMPK, PGC1α, Nrf2, HO1, SOD, GPX4, and GSH, but decreased the levels of 4HNE, MDA, ACSL4, GSSG, and iron concentration in the ipsilateral hemisphere at 24 h after SAH. Dorsomorphin or SR18292 partially abolished the beneficial effects of puerarin exerted on neurological dysfunction, oxidative stress injury, and ferroptosis. In conclusion, puerarin improved neurobehavioral impairments and attenuated oxidative-stress-induced brain ferroptosis after SAH in rats. The neuroprotection acted through the activation of the AMPK/PGC1α/Nrf2-signaling pathway. Thus, puerarin may serve as new therapeutics against EBI in SAH patients.

CTRP3 alleviates myocardial ischemia/reperfusion injury in mice through activating LAMP1/JIP2/JNK pathway

Myocardial ischemia reperfusion (I/R) injury is an important complication of myocardial infarction reperfusion therapy, and no effective treatment has been identified. Based on preexisting evidence, C1q/tumor necrosis factor-related protein 3 (CTRP3) has been reported to be closely associated with myocardial dysfunction. In this study, we found that CTRP3 was downregulated in acute coronary syndrome (ACS) patients and myocardial I/R mice. Silence of CTRP3 aggravated cardiac systolic function due to I/R of mice, while CTRP3 overexpression ameliorated cardiac function. Moreover, overexpression of CTRP3 improved I/R inhibitory effects on the levels of creatinine phosphokinase (CPK), lactate dehydrogenase (LDH) and cardiac troponin-I (cTn-I), myocardial infarction area, the intensity of the 3-nitrotyrosine (3-NT), apoptosis and protein levels of LAMP1, JNK-Interacting Protein-2 (JIP-2) and JNK, while these effects could be exacerbated by downregulation of CTRP3. Co-IP experiments could identify physical interactions between CTRP3 and lysosomal-associated membrane protein 1 (LAMP1) and Numb and JIP2. LAMP1 silence aggravated the inhibition effects of I/R on JIP2 and JNK protein expression, CPK, LDH and cTn-I levels and caspase-3 activity, while overexpression of LAMP1 recovered these inhibition effects of I/R. JNK inhibitor (SP600125) could reverse the inhibitory effects of CTRP3 overexpression on CPK, LDH, cTn-I, myocardial infarction, strong positive staining for 3-NT and apoptosis. These findings demonstrated that CTRP3 protected against injury caused by myocardial I/R through activating LAMP1/JIP2/JNK pathway to attenuate myocardial injury, improve left ventricular function, decrease myocardial infarction, and reduce myocardial apoptosis.

C1q/tumor necrosis factor-related protein-3 (CTRP3) activated by forkhead box O4 (FOXO4) down-regulation protects retinal pericytes against high glucose-induced oxidative damage through nuclear factor erythroid 2-related factor 2 (Nrf2)/Nuclear factor-kappaB (NF-κB) signaling

Diabetic retinopathy (DR) remains a major cause of blindness among diabetes mellitus patients. C1q/tumor necrosis factor-related protein-3 (CTRP3) is a novel adipokine which is associated with multiple types of metabolism. Nevertheless, little is known about the role of CTRP3 in high glucose (HG)-induced human retinal pericytes (HRPs). This study set out to assess the influence of CTRP3 on HG-induced HRPs and elucidate the latent regulatory mechanism. RT-qPCR and Western blot were to analyze CTRP3 and forkhead box O4 (FOXO4) expression. Western blot was also utilized to detect the protein levels of apoptosis-related factors and nuclear factor erythroid 2-related factor 2 (Nrf2)/Nuclear factor-kappaB (NF-κB) signaling-related factors. CCK-8 was to measure cell proliferation while TUNEL assay was to estimate cell apoptosis. Levels of oxidative stress biomarkers including manganese (MnSOD), catalase (CAT) and malonedialdehyde (MDA) were evaluated by the corresponding kits. JASPAR database, ChIP and luciferase reporter assay were to verify the interaction between FOXO4 and CTRP3 promoter. The experimental results uncovered that CTRP3 expression was decreased in HG-stimulated HRPs. Moreover, CTRP3 overexpression strengthened the viability while abrogated the apoptosis and oxidative stress of HG-induced HRPs. Furthermore. FOXO4 was up-regulated in HG-induced HRPs. Besides, FOXO4 bond to CTRP3 promoter and inhibited CTRP3 transcription to modulate the Nrf2/NF-κB signaling pathway. FOXO4 up-regulation reversed the influence of CTRP3 elevation on the proliferation, apoptosis and oxidative stress of HG-induced HRPs. To be summarized, CTRP3 negatively modulated by FOXO4 prevented HG-induced oxidative damage in DR via modulation of Nrf2/NF-κB signaling.

Emerging Role of cAMP/AMPK Signaling

The 5′-Adenosine monophosphate (AMP)-activated protein kinase (AMPK) is a natural energy sensor in mammalian cells that plays a key role in cellular and systemic energy homeostasis. At the cellular level, AMPK supports numerous processes required for energy and redox homeostasis, including mitochondrial biogenesis, autophagy, and glucose and lipid metabolism. Thus, understanding the pathways regulating AMPK activity is crucial for developing strategies to treat metabolic disorders. Mounting evidence suggests the presence of a link between cyclic AMP (cAMP) and AMPK signaling. cAMP signaling is known to be activated in circumstances of physiological and metabolic stress due to the release of stress hormones, such as adrenaline and glucagon, which is followed by activation of membrane-bound adenylyl cyclase and elevation of cellular cAMP. Because the majority of physiological stresses are associated with elevated energy consumption, it is not surprising that activation of cAMP signaling may promote AMPK activity. Aside from the physiological role of the cAMP/AMPK axis, numerous reports have suggested its role in several pathologies, including inflammation, ischemia, diabetes, obesity, and aging. Furthermore, novel reports have provided more mechanistic insight into the regulation of the cAMP/AMPK axis. In particular, the role of distinct cAMP microdomains generated by soluble adenylyl cyclase in regulating basal and induced AMPK activity has recently been demonstrated. In the present review, we discuss current advances in the understanding of the regulation of the cAMP/AMPK axis and its role in cellular homeostasis and explore some translational aspects.

Multifaced role of protein deacetylase sirtuins in neurodegenerative disease

Sirtuins, a class III histone/protein deacetylase, is a central regulator of metabolic function and cellular stress response. This plays a pivotal role in the pathogenesis and progression of diseases such as cancer, neurodegeneration, metabolic syndromes, and cardiovascular disease. Sirtuins regulate biological and cellular processes, for instance, mitochondrial biogenesis, lipid and fatty acid oxidation, oxidative stress, gene transcriptional activity, apoptosis, inflammatory response, DNA repair mechanism, and autophagic cell degradation, which are known components for the progression of the neurodegenerative diseases (NDDs). Emerging evidence suggests that sirtuins are the useful molecular targets against NDDs like, Alzheimer's Disease (AD), Parkinson's Disease (PD), Huntington's Disease (HD), and Amyotrophic Lateral Sclerosis (ALS). However, the exact mechanism of neuroprotection mediated through sirtuins remains unsettled. The manipulation of sirtuins activity with its modulators, calorie restriction (CR), and micro RNAs (miR) is a novel therapeutic approach for the treatment of NDDs. Herein, we reviewed the current putative therapeutic role of sirtuins in regulating synaptic plasticity and cognitive functions, which are mediated through the different molecular phenomenon to prevent neurodegeneration. We also explained the implications of sirtuin modulators, and miR based therapies for the treatment of life-threatening NDDs.

Function and Mechanism of Trimetazidine in Myocardial Infarction-Induced Myocardial Energy Metabolism Disorder Through the SIRT1-AMPK Pathway

Myocardial energy metabolism (MEM) is an important factor of myocardial injury. Trimetazidine (TMZ) provides protection against myocardial ischemia/reperfusion injury. The current study set out to evaluate the effect and mechanism of TMZ on MEM disorder induced by myocardial infarction (MI). Firstly, a MI mouse model was established by coronary artery ligation, which was then treated with different concentrations of TMZ (5, 10, and 20 mg kg^-1 day^-1). The results suggested that TMZ reduced the heart/weight ratio in a concentration-dependent manner. TMZ also reduced the levels of Bax and cleaved caspase-3 and promoted Bcl-2 expression. In addition, TMZ augmented adenosine triphosphate (ATP) production and superoxide dismutase (SOD) activity induced by MI and decreased the levels of lipid peroxide (LPO), free fatty acids (FFA), and nitric oxide (NO) in a concentration-dependent manner (all P < 0.05). Furthermore, an H₂O₂-induced cell injury model was established and treated with different concentrations of TMZ (1, 5, and 10 μM). The results showed that SIRT1 overexpression promoted ATP production and reactive oxygen species (ROS) activity and reduced the levels of LPO, FFA, and NO in H9C2 cardiomyocytes treated with H₂O₂ and TMZ. Silencing SIRT1 suppressed ATP production and ROS activity and increased the levels of LPO, FFA, and NO (all P < 0.05). TMZ activated the SIRT1-AMPK pathway by increasing SIRT1 expression and AMPK phosphorylation. In conclusion, TMZ inhibited MI-induced myocardial apoptosis and MEM disorder by activating the SIRT1-AMPK pathway.

Stimulation of AMPK Prevents Diabetes-Induced Photoreceptor Cell Degeneration

Diabetic retinopathy (DR) is a kind of severe retinal neurodegeneration. The advanced glycation end products (AGEs) affect autophagy, and mitochondrial function is involved in DR. Adenosine-activated protein kinase (AMPK) is an important metabolic sensor that can regulate energy homeostasis in cells. However, the effect of AMPK in DR is still not fully understood. In this study, we investigated the effect of AMPK on diabetes-induced photoreceptor cell degeneration. In vivo, a diabetic mouse model was established by streptozotocin (STZ) injection. Haematoxylin-eosin (HE) staining was used to observe retinal morphology and measure the thicknesses of different layers in the retina. Electroretinogram (ERG) was used to evaluate retinal function. In vitro, 661w cells were treated with AGEs with/without an AMPK agonist (metformin) or AMPK inhibitor (compound C). Flow cytometry and CCK-8 assays were used to analyse apoptosis. Mitochondrial membrane potential was analysed by JC-1. Western blotting and qRT-PCR were used to examine the expression of related proteins and genes, respectively. The wave amplitude and the thickness of the outer nuclear layer were decreased in diabetic mice. The expression of rhodopsin and opsin was also decreased in diabetic mice. In vitro, the percentage of apoptotic cells was increased, the expression of the apoptosis-related protein Bax was increased, and Bcl-2 was decreased after AGE treatment in 661w cells. The expression of the autophagy-related protein LC3 was decreased, and p62 was increased. The mitochondrial-related gene expression and membrane potential were decreased, and mitochondrial morphology was abnormal, as observed by TEM. However, AMPK stimulation ameliorated this effect. These results indicate that AMPK stimulation can delay diabetes-induced photoreceptor degeneration by regulating autophagy and mitochondrial function.

Dietary Fe3O4 Nanozymes Prevent the Injury of Neurons and Blood-Brain Barrier Integrity from Cerebral Ischemic Stroke

Cerebral ischemic stroke stimulates excessive reactive oxygen species, which lead to blood-brain-barrier disruption, neuron death, and aggravated cerebral infarction. Thus, it is critical to develop an antioxidant strategy for stroke treatment. Herein, we report a dietary strategy to promote stroke healing using iron oxide (Fe₃O₄) nanoparticles with intrinsic enzyme-like activities. We find that Fe₃O₄ nanozymes exhibit triple enzyme-like activities, peroxidase, catalase, and superoxide dismutase, thus potentially possessing the ability to regulate the ROS level. Importantly, intragastric administration of PEG-modified Fe₃O₄ nanozymes significantly reduces cerebral infarction and neuronal death in a rodent model following cerebral ischemic stroke. Ex vivo analysis shows that PEG-modified Fe₃O₄ nanozymes localize in the cerebral vasculature, ameliorate local redox state with decreased malondialdehyde and increased Cu/Zn SOD, and facilitate blood-brain-barrier recovery by elevating ZO-1 and Claudin-5 in the hippocampus. Altogether, our results suggest that dietary PEG-modified Fe₃O₄ nanozymes can facilitate blood-brain-barrier reconstruction and protect neurons following ischemic stroke.