Ischemia-induced upregulation of autophagy preludes dysfunctional lysosomal storage and associated synaptic impairments in neurons

CRHR1 antagonist alleviated depression-like behavior by downregulating p62 in a rat model of post-stroke depression

Post-stroke depression (PSD) is a complication of cerebrovascular disease, which can increase mortality after stroke. CRH is one of the main signaling peptides released after activation of the hypothalamic-pituitary-adrenal (HPA) axis in response to stress. It affects synaptic plasticity by regulating inflammation, oxidative stress and autophagy in the central nervous system. And the loss of spines exacerbates depression-like behavior. Therefore, synaptic deficits induced by CRH may be related to post-stroke depression. However, the underlying mechanism remains unclear. The Keap1-Nrf2 complex is one of the core components of the antioxidant response. As an autophagy associated protein, p62 participates in the Keap1-NrF2 pathway through its Keap1 interaction domain. Oxidative stress is involved in the feedback regulation between Keap1-Nrf2 pathway and p62.However, whether the relationship between CRH and the Keap1-Nrf2-p62 pathway is involved in PSD remains unknown. This study found that serum levels of CRH in 22 patients with PSD were higher than those in healthy subjects. We used MCAO combined with CUMS single-cage SD rats to establish an animal model of PSD. Animal experiments showed that CRHR1 antagonist prevented synaptic loss in the hippocampus of PSD rats and alleviated depression-like behavior. CRH induced p62 accumulation in the prefrontal cortex of PSD rats through CRHR1. CRHR1 antagonist inhibited Keap1-Nrf2-p62 pathway by attenuating oxidative stress. In addition, we found that abnormal accumulation of p62 induces PSD. It alleviates depression-like behavior by inhibiting the expression of p62 and promoting the clearance of p62 in PSD rats. These findings can help explore the pathogenesis of PSD and design targeted treatments for PSD.

THSG alleviates cerebral ischemia/reperfusion injury via the GluN2B-CaMKII-ERK1/2 pathway

BACKGROUND

The potential therapeutic targeting of PINK1-PARK2-mediated mitophagy against cerebral ischemia/reperfusion (CI/R) injury involves the pathophysiological processes of neurovascular unit (NVU) and is closely associated with N-methyl-D-aspartate receptors (NMDARs) commonly expressed in NVU. 2,3,5,4'-Tetrahydroxy-stilbene-2-O-β-D-glucoside (THSG), a compound derived from the traditional Chinese medicine Polygonum multiflorum Thunb., has demonstrated notable neuroprotective properties against CI/R injury. However, it remains unclear whether THSG exerts its protective effects through GluN2B related PINK1/ PARK2 pathway.

PURPOSE

This study aims to explore the pharmacological effects of THSG on alleviating CI/R injury via the GluN2B-CaMKII-ERK1/2 pathway.

METHODS

THSG neuroprotection against CI/R injury was studied in transient middle cerebral artery occlusion/reversion (tMCAO/R) model rats and in oxygen and glucose deprivation/ reoxygenation (OGD/R) induced neurons. PINK1-PARK2-mediated mitophagy involvement in the protective effect of THSG was investigated in tMCAO/R rats and OGD/R-induced neurons via THSG and 3-methyladenine (3-MA) treatment. Furthermore, the beneficial role of GluN2B in reperfusion and its contribution to the THSG effect via CaMKII-ERK1/2 and PINK1-PARK2-mediated mitophagy was explored using the GluN2B-selective antagonist Ro 25-6981 both in vivo and in vitro. Finally, the interaction between THSG and GluN2B was evaluated using molecular docking.

RESULTS

THSG significantly reduced infarct volume, neurological deficits, penumbral neuron structure, and functional damage, upregulated the inhibitory apoptotic marker Bcl-2, and suppressed the increase of pro-apoptotic proteins including cleaved caspase-3 and Bax in tMCAO/R rats. THSG (1 μM) markedly improved the neuronal survival under OGD/R conditions. Furthermore, THSG promoted PINK1 and PARK2 expression and increased mitophagosome numbers and LC3-II-LC3-I ratio both in vivo and in vitro. The effects of THSG were considerably abrogated by the mitophagy inhibitor 3-MA in OGD/R-induced neurons. Inhibiting GluN2B profoundly decreased mitophagosome numbers and OGD/R-induced neuronal viability. Specifically, inhibiting GluN2B abolished the protection of THSG against CI/R injury and reversed the upregulation of PINK1-PARK2-mediated mitophagy by THSG. Inhibiting GluN2B eliminated THSG upregulation of ERK1/2 and CaMKII phosphorylation. The molecular docking analysis results demonstrated that THSG bound to GluN2B (binding energy: -5.2 ± 0.11 kcal/mol).

CONCLUSIONS

This study validates the premise that THSG alleviates CI/R injury by promoting GluN2B expression, activating CaMKII and ERK1/2, and subsequently enhancing PINK1-PARK2-mediated mitophagy. This work enlightens the potential of THSG as a promising candidate for novel therapeutic strategies for treating ischemic stroke.

Is There a Role for SGLT2 Inhibitors in Patients with End-Stage Kidney Disease?

PURPOSE OF REVIEW

Chronic kidney disease and end-stage kidney disease (ESKD) are well-established risk factors for cardiovascular disease (CVD), the leading cause of mortality in the dialysis population. Conventional therapies, such as statins, blood pressure control, and renin-angiotensin-aldosterone system blockade, have inadequately addressed this cardiovascular risk, highlighting the unmet need for effective treatment strategies. Sodium-glucose transporter 2 (SGLT2) inhibitors have demonstrated significant renal and cardiovascular benefits among patients with type 2 diabetes, heart failure, or CKD at risk of progression. Unfortunately, efficacy data in dialysis patients is lacking as ESKD was an exclusion criterion for all major clinical trials of SGLT2 inhibitors. This review explores the potential of SGLT2 inhibitors in improving cardiovascular outcomes among patients with ESKD, focusing on their direct cardiac effects.

RECENT FINDINGS

Recent clinical and preclinical studies have shown promising data for the application of SGLT2 inhibitors to the dialysis population. SGLT2 inhibitors may provide cardiovascular benefits to dialysis patients, not only indirectly by preserving the remaining kidney function and improving anemia but also directly by lowering intracellular sodium and calcium levels, reducing inflammation, regulating autophagy, and alleviating oxidative stress and endoplasmic reticulum stress within cardiomyocytes and endothelial cells. This review examines the current clinical evidence and experimental data supporting the use of SGLT2 inhibitors, discusses its potential safety concerns, and outlines ongoing clinical trials in the dialysis population. Further research is needed to evaluate the safety and effectiveness of SGLT2 inhibitor use among patients with ESKD.

Hesperidin Alleviates Hepatic Injury Caused by Deoxynivalenol Exposure through Activation of mTOR and AKT/GSK3β/TFEB Pathways

Deoxynivalenol (DON) is a common agricultural mycotoxin that is chemically stable and not easily removed from cereal foods. When organisms consume food made from contaminated crops, it can be hazardous to their health. Numerous studies in recent years have found that hesperidin (HDN) has hepatoprotective effects on a wide range of toxins. However, few scholars have explored the potential of HDN in attenuating DON-induced liver injury. In this study, we established a low-dose DON exposure model and intervened with three doses of HDN, acting on male C57 BL/6 mice and AML12 cells, which served as in vivo and in vitro models, respectively, to investigate the protective mechanism of HDN against DON exposure-induced liver injury. The results suggested that DON disrupted hepatic autophagic fluxes, thereby impairing liver structure and function, and HDN significantly attenuated these changes. Further studies revealed that HDN alleviated DON-induced excessive autophagy through the mTOR pathway and DON-induced lysosomal dysfunction through the AKT/GSK3β/TFEB pathway. Overall, our study suggested that HDN could ameliorate DON-induced autophagy flux disorders via the mTOR pathway and the AKT/GSK3β/TFEB pathway, thereby reducing liver injury.

Morphine Induced Neuroprotection in Ischemic Stroke by Activating Autophagy Via mTOR-Independent Activation of the JNK1/2 Pathway

Morphine (Mor) has exhibited efficacy in safeguarding neurons against ischemic injuries by simulating ischemic/hypoxic preconditioning (I/HPC). Concurrently, autophagy plays a pivotal role in neuronal survival during IPC against ischemic stroke. However, the involvement of autophagy in Mor-induced neuroprotection and the potential mechanisms remain elusive. Our experiments further confirmed the effect of Mor in cellular and animal models of ischemic stroke and explored its potential mechanism. The findings revealed that Mor enhanced cell viability in a dose-dependent manner by augmenting autophagy levels and autophagic flux in neurons subjected to oxygen-glucose deprivation/reoxygenation (OGD/R). Pretreatment of Mor improved neurological outcome and reduced infarct size in mice with middle cerebral artery occlusion/reperfusion (MCAO/R) at 1, 7 and 14 days. Moreover, the use of autophagy inhibitors nullified the protective effects of Mor, leading to reactive oxygen species (ROS) accumulation, increased loss of mitochondrial membrane potential (MMP) and neuronal apoptosis in OGD/R neurons. Results further demonstrated that Mor-induced autophagy activation was regulated by mTOR-independent activation of the c-Jun NH2- terminal kinase (JNK)1/2 Pathway, both in vitro and in vivo. Overall, these findings suggested Mor-induced neuroprotection by activating autophagy, which were regulated by JNK1/2 pathway in ischemic stroke.

PGC-1α in the hippocampus mediates depressive-like and stress-coping behaviours and regulates excitatory synapses in the dentate gyrus in mice

Decreased hippocampal synaptic plasticity is an important pathological change in stress-related mood disorders, including major depressive disorder. However, the underlying mechanism is unclear. PGC-1α, a transcriptional coactivator, is a key factor in synaptic plasticity. We investigated the relationships between changes in hippocampal PGC-1α expression and depressive-like and stress-coping behaviours, and whether they are related to hippocampal synapses. Adeno-associated virus was used to alter hippocampal PGC-1α expression in male C57BL/6 mice. The sucrose preference test and forced swimming test were used to assess their depressive-like and stress-coping behaviours, respectively. Immunohistochemistry and stereology were used to calculate the total number of excitatory synapses in each hippocampal subregion (the cornu ammonis (CA) 1, CA3, and dentate gyrus). Immunofluorescence was used to visualize the changes in dendritic structure. Western blotting was used to detect the expression of hippocampal PGC-1α and mitochondrial-associated proteins, such as UCP2, NRF1 and mtTFAs. Our results showed that mice with downregulated PGC-1α expression in the hippocampus exhibited depressive-like and passive stress-coping behaviours, while mice with upregulated PGC-1α in the hippocampus exhibited increased stress-coping behaviours. Moreover, the downregulation of hippocampal PGC-1α expression resulted in a decrease in the number of excitatory synapses in the DG and in the protein expression of UCP2 in the hippocampus. Alternatively, upregulation of hippocampal PGC-1α yielded the opposite results. This suggests that hippocampal PGC-1α is involved in regulating depressive-like and stress-coping behaviours and modulating the number of excitatory synapses in the DG. This provides new insight for the development of antidepressants.

Cystatin C loaded in brain-derived extracellular vesicles rescues synapses after ischemic insult in vitro and in vivo

Synaptic loss is an early event in the penumbra area after an ischemic stroke. Promoting synaptic preservation in this area would likely improve functional neurological recovery. We aimed to detect proteins involved in endogenous protection mechanisms of synapses in the penumbra after stroke and to analyse potential beneficial effects of these candidates for a prospective stroke treatment. For this, we performed Liquid Chromatography coupled to Mass Spectrometry (LC-MS)-based proteomics of synaptosomes isolated from the ipsilateral hemispheres of mice subjected to experimental stroke at different time points (24 h, 4 and 7 days) and compared them to sham-operated mice. Proteomic analyses indicated that, among the differentially expressed proteins between the two groups, cystatin C (CysC) was significantly increased at 24 h and 4 days following stroke, before returning to steady-state levels at 7 days, thus indicating a potential transient and intrinsic rescue mechanism attempt of neurons. When CysC was applied to primary neuronal cultures subjected to an in vitro model of ischemic damage, this treatment significantly improved the preservation of synaptic structures. Notably, similar effects were observed when CysC was loaded into brain-derived extracellular vesicles (BDEVs). Finally, when CysC contained in BDEVs was administered intracerebroventricularly to stroked mice, it significantly increased the expression of synaptic markers such as SNAP25, Homer-1, and NCAM in the penumbra area compared to the group supplied with empty BDEVs. Thus, we show that CysC-loaded BDEVs promote synaptic protection after ischemic damage in vitro and in vivo, opening the possibility of a therapeutic use in stroke patients.

Inhibition of autophagosome-lysosome fusion contributes to TDCIPP-induced Aβ1-42 production in N2a-APPswe cells

Alzheimer's disease is the most common form of dementia and is characterized by cognitive impairment. The disruption of autophagosome-lysosome function has been linked to the pathogenesis of Alzheimer's disease. Tris (1,3-dichloro-2-propyl) phosphate (TDCIPP) is a widely used organophosphorus flame retardant that has the potential to cause neuronal damage. We found that TDCIPP significantly increased the expression of β-site amyloid precursor protein (APP)-cleaving enzyme 1 (BACE1), presenilin-1 (PS1) and Aβ42. Proteomic studies with TMT labeling revealed changes in the profiles of N2a-APPswe cells after exposure to TDCIPP. Proteomic and bioinformatics analyses revealed that lysosomal proteins were dysregulated in N2a-APPswe cells after treatment with TDCIPP. The LC3, P62, CTSD, and LAMP1 levels were increased after TDCIPP exposure, and dysregulated protein expression was validated by Western blotting. The exposure to TDCIPP led to the accumulation of autophagosomes, and this phenomenon was enhanced in the presence of chloroquine (CQ). Our results revealed for the first time that TDCIPP could be a potential environmental risk factor for AD development. The inhibition of autophagosome-lysosome fusion may have a significant impact on the generation of Aβ1-42 in response to TDCIPP.

YTHDC1/CRM1 Facilitates m6A-Modified circRNA388 Nuclear Export to Induce Coelomocyte Autophagy via the miR-2008/ULK Axis in Apostichopus japonicus

N 6-methyladenosine (m6A), the most prevalent internal modification in eukaryotic RNA, was able to mediate circular RNA (circRNA) function in many immune processes. Nevertheless, the functional role of m6A-modified circRNAs in innate immunity of invertebrates remained unclear. In this study, we identified m6A-modified circRNA388 from cultured sea cucumber (Apostichopus japonicus) coelomocytes, which was mainly detected in cytoplasm after Vibrio splendidus infection. A knockdown assay indicated that cytoplasm circRNA388 promoted coelomocyte autophagy and decreased the number of intracellular V. splendidus. Mechanistically, the circRNA388 in the cytoplasm directly sponged miR-2008 to block its interaction with Unc-51-like kinase 1 from A. japonicus (AjULK) and further promoted autophagy to resist V. splendidus infection. More importantly, we found that m6A modification was vital to circRNA388 nuclear export with YTH domain-containing protein 1 from A. japonicus (AjYTHDC1) as the reader. AjYTHDC1 facilitated the nuclear export of m6A-modified circRNA388 via interaction with exportin-1 (chromosomal maintenance 1) from A. japonicus (AjCRM1). Knockdown of AjCRM1 could significantly decrease the content of cytoplasm circRNA388. Overall, our results provide the first evidence that nuclear export of m6A-modified circRNA388 is dependent on the novel AjCRM1 to our knowledge, which was further promoted coelomocyte autophagy by miR-2008/AjULK axis to clear intracellular V. splendidus.

KAT7/HMGN1 signaling epigenetically induces tyrosine phosphorylation-regulated kinase 1A expression to ameliorate insulin resistance in Alzheimer's disease

BACKGROUND

Epidemiological studies have revealed a correlation between Alzheimer's disease (AD) and type 2 diabetes mellitus (T2D). Insulin resistance in the brain is a common feature in patients with T2D and AD. KAT7 is a histone acetyltransferase that participates in the modulation of various genes.

AIM

To determine the effects of KAT7 on insulin patients with AD.

METHODS

APPswe/PS1-dE9 double-transgenic and db/db mice were used to mimic AD and diabetes, respectively. An in vitro model of AD was established by Aβ stimulation. Insulin resistance was induced by chronic stimulation with high insulin levels. The expression of microtubule-associated protein 2 (MAP2) was assessed using immunofluorescence. The protein levels of MAP2, Aβ, dual-specificity tyrosine phosphorylation-regulated kinase-1A (DYRK1A), IRS-1, p-AKT, total AKT, p-GSK3β, total GSK3β, DYRK1A, and KAT7 were measured via western blotting. Accumulation of reactive oxygen species (ROS), malondialdehyde (MDA), and SOD activity was measured to determine cellular oxidative stress. Flow cytometry and CCK-8 assay were performed to evaluate neuronal cell death and proliferation, respectively. Relative RNA levels of KAT7 and DYRK1A were examined using quantitative PCR. A chromatin immunoprecipitation assay was conducted to detect H3K14ac in DYRK1A.

RESULTS

KAT7 expression was suppressed in the AD mice. Overexpression of KAT7 decreased Aβ accumulation and MAP2 expression in AD brains. KAT7 overexpression decreased ROS and MDA levels, elevated SOD activity in brain tissues and neurons, and simultaneously suppressed neuronal apoptosis. KAT7 upregulated levels of p-AKT and p-GSK3β to alleviate insulin resistance, along with elevated expression of DYRK1A. KAT7 depletion suppressed DYRK1A expression and impaired H3K14ac of DYRK1A. HMGN1 overexpression recovered DYRK1A levels and reversed insulin resistance caused by KAT7 depletion.

CONCLUSION

We determined that KAT7 overexpression recovered insulin sensitivity in AD by recruiting HMGN1 to enhance DYRK1A acetylation. Our findings suggest that KAT7 is a novel and promising therapeutic target for the resistance in AD.

Kaempferol improves Pb-induced cognitive impairments via inhibiting autophagy

Kaempferol (Kam) is a flavonoid antioxidant found in fruits and vegetables, which was discovered as neuroprotective antioxidants. Lead (Pb), an environmental pollution, could induce learning and memory deficits. Nevertheless, little is known about the mechanisms underlying Kam actions in Pb-induced learning and memory deficits. In this study, we investigated the effects of Kam on Pb-induced cognitive deficits. Pb-exposed rats were treated with 50 mg/kg Kam from postnatal day (PND) 30 to PND 60. Then, Y-maze and Morris water maze have been used to detect the spatial memory in all groups of rats. Hematoxylin and eosin (HE) staining and Nissl staining were used to analyze the neuronal structure damages. The results found Kam treatment improved the learning and memory ability and alleviated hippocampal neuronal pathological damages. Besides, Kam could significantly reverse the synaptic transmission related protein expression including PSD95 and NMDAR2B. Further research found that Kam downregulated autophagy markers, P62, ATG5, Beclin1, and LC3-II. Furthermore, 3-MA, autophagy inhibitor, increased the levels of NMDAR2B and PSD95 in Pb-induced PC12 cells, indicating Kam alleviated Pb-induced neurotoxicity through inhibiting autophagy activation. Our results showed that Kam could ameliorate Pb-induced cognitive impairments and neuronal damages by decreasing Pb-induced excess autophagy accumulation.

Berberine Alleviates Ischemic Brain Injury by Enhancing Autophagic Flux via Facilitation of TFEB Nuclear Translocation

Berberine has been demonstrated to alleviate cerebral ischemia/reperfusion injury, but its neuroprotective mechanism has yet to be understood. Studies have indicated that ischemic neuronal damage was frequently driven by autophagic/lysosomal dysfunction, which could be restored by boosting transcription factor EB (TFEB) nuclear translocation. Therefore, this study investigated the pharmacological effects of berberine on TFEB-regulated autophagic/lysosomal signaling in neurons after cerebral stroke. A rat model of ischemic stroke and a neuronal ischemia model in HT22 cells were prepared using middle cerebral artery occlusion (MCAO) and oxygen-glucose deprivation (OGD), respectively. Berberine was pre-administered at a dose of 100[Formula: see text]mg/kg/d for three days in rats and 90[Formula: see text][Formula: see text]M in HT22 neurons for 12[Formula: see text]h. 24[Formula: see text]h after MCAO and 2[Formula: see text]h after OGD, the penumbral tissues and OGD neurons were obtained to detect nuclear and cytoplasmic TFEB, and the key proteins in the autophagic/lysosomal pathway were examined using western blot and immunofluorescence, respectively. Meanwhile, neuron survival, infarct volume, and neurological deficits were assessed to evaluate the therapeutic efficacy. The results showed that berberine prominently facilitated TFEB nuclear translocation, as indicated by increased nuclear expression in penumbral neurons as well as in OGD HT22 cells. Consequently, both autophagic activity and lysosomal capacity were simultaneously augmented to alleviate the ischemic injury. However, berberine-conferred neuroprotection could be greatly counteracted by lysosomal inhibitor Bafilomycin A1 (Baf-A1). Meanwhile, autophagy inhibitor 3-Methyladenine (3-MA) also slightly neutralized the pharmacological effect of berberine on ameliorating autophagic/lysosomal dysfunction. Our study suggests that berberine-induced neuroprotection against ischemic stroke is elicited by enhancing autophagic flux via facilitation of TFEB nuclear translocation in neurons.

Autophagy inhibitors 3-MA and BAF may attenuate hippocampal neuronal necroptosis after global cerebral ischemia-reperfusion injury in male rats by inhibiting the interaction of the RIP3/AIF/CypA complex

Our previous study found that receptor interacting protein 3 (RIP3) and apoptosis-inducing factor (AIF) were involved in neuronal programmed necrosis during global cerebral ischemia-reperfusion (I/R) injury. Here, we further studied its downstream mechanisms and the role of the autophagy inhibitors 3-methyladenine (3-MA) and bafilomycin A1 (BAF). A 20-min global cerebral I/R injury model was constructed using the 4-vessel occlusion (4-VO) method in male rats. 3-MA and BAF were injected into the lateral ventricle 1 h before ischemia. Spatial and activation changes of proteins were detected by immunofluorescence (IF), and protein interaction was determined by immunoprecipitation (IP). The phosphorylation of H2AX (γ-H2AX) and activation of mixed lineage kinase domain-like protein (p-MLKL) occurred as early as 6 h after reperfusion. RIP3, AIF, and cyclophilin A (CypA) in the neurons after I/R injury were spatially overlapped around and within the nucleus and combined with each other after reperfusion. The survival rate of CA1 neurons in the 3-MA and BAF groups was significantly higher than that in the I/R group. Autophagy was activated significantly after I/R injury, which was partially inhibited by 3-MA and BAF. Pretreatment with both 3-MA and BAF almost completely inhibited nuclear translocation, spatial overlap, and combination of RIP3, AIF, and CypA proteins. These findings suggest that after global cerebral I/R injury, RIP3, AIF, and CypA translocated into the nuclei and formed the DNA degradation complex RIP3/AIF/CypA in hippocampal CA1 neurons. Pretreatment with autophagy inhibitors could reduce neuronal necroptosis by preventing the formation of the RIP3/AIF/CypA complex and its nuclear translocation.

MCC950 reduces autophagy and improves cognitive function by inhibiting NLRP3-dependent neuroinflammation in a rat model of Alzheimer's disease

Alzheimer's disease (AD) is the seventh most common cause of mortality and one of the major causes of disability and vulnerability in the elderly. AD is characterized by gradual cognitive deterioration, the buildup of misfolded amyloid beta (Aβ) peptide, and the generation of neurofibrillary tangles. Despite enormous scientific progress, there is no effective cure for AD. Thus, exploring new treatment options to stop AD or at least slow down its progress is important. In this study, we investigated the potential therapeutic effects of MCC950 on NLRP3-mediated inflammasome-driven inflammation and autophagy in AD. Rats treated with streptozotocin (STZ) exhibited simultaneous activation of the NLRP3 inflammasome and autophagy, as confirmed by Western blot, immunofluorescence, and co-immunoprecipitation analyses. MCC950, a specific NLRP3 inhibitor, was intraperitoneally administered (50 mg/kg body weight) to rats with AD-like symptoms induced by intracerebroventricular STZ injections (3 mg/kg body weight). MCC950 effectively suppressed STZ-induced cognitive impairment and anxiety by inhibiting NLRP3-dependent neuroinflammation. Moreover, our findings indicate that MCC950 exerts neuroprotective effects by attenuating autophagy in neuronal cells. The inhibiting effects of MCC950 on inflammasome activation and autophagy were reproduced in vitro, provding further mechansistic insights into MCC950 therapeutic action. Our findings suggest that MCC950 impedes the progression of AD and may also improve cognitive function through the mitigation of autophagy and NLRP3 inflammasome inhibition.

YAP promotes the healing of ischemic wounds by reducing ferroptosis in skin fibroblasts through inhibition of ferritinophagy

The impaired healing of chronic wounds is often attributed to the ischemic and hypoxic microenvironment, leading to increased cell death. Ferroptosis, a novel form of cell death unveiled in recent years, could potentially be linked with the process of wound healing. In this study, we explored the significance and mechanism of ferroptosis in ischemic wounds. Using transmission electron microscopy, Western blot, flow cytometry, immunofluorescence, and glutathione (GSH) assay, we observed that the death of primary mouse skin fibroblasts induced by oxygen and glucose deprivation (OGD) was associated with ferroptosis. Specifically, we observed elevated intracellular Fe2+ and lipid peroxidation levels and decreased GSH levels in vitro, indicative of ferroptosis. Importantly, we found that ferroptosis in OGD-treated skin fibroblasts was dependent on autophagy, as the autophagy inhibitor chloroquine phosphate (CHQ) significantly reduced ferroptosis induced by OGD. Moreover, our study revealed that NCOA4-mediated ferritinophagy significantly contributed to the occurrence of ferroptosis induced by OGD in skin fibroblasts. Additionally, we identified the involvement of YAP in the regulation of ferritinophagy, with YAP suppressing NCOA4 expression in OGD-treated skin fibroblasts, thereby reducing ferroptosis. Furthermore, in ischemic wound models in mice, both inhibitors of ferroptosis and autophagy promoted wound healing, while a YAP inhibitor, verteporfin, delayed wound healing. In conclusion, these findings indicate that ferroptosis, regulated by YAP through ferritinophagy inhibition, presents a novel mechanism responsible for the delayed healing of ischemic wounds. Understanding this process could offer promising therapeutic targets to improve wound healing in ischemic conditions.

Ortho-silicic Acid Prevents Glucocorticoid-Induced Femoral Head Necrosis by Promoting Akt Phosphorylation to Inhibit Endoplasmic Reticulum Stress-Mediated Apoptosis and Enhance Angiogenesis and Osteogenesis

Glucocorticoid-induced osteonecrosis of the femoral head (SONFH) is the most prevalent form of secondary osteonecrosis affecting the femoral head. Glucocorticoids can cause damage to both vascular endothelial cells and osteoblasts. Previous studies have demonstrated that silicon can improve the resistance of vascular endothelial cells to oxidative stress and positively impact bone health. However, the impact of silicon on SONFH has yet to be investigated. We examined the influence of ortho-silicic acid (OSA, Si(OH)4) on the apoptosis and proliferation of vascular endothelial cells after glucocorticoid induction. Additionally, we evaluated the expression of apoptosis-related genes such as cleaved-caspase-3, Bcl-2 and Bax. The impact of glucocorticoids and OSA on the function of vascular endothelial cells was evaluated through wound healing, transwell and angiogenesis assays. Osteogenic function was subsequently evaluated through alizarin red staining, alkaline phosphatase staining and expression levels of osteogenic genes like RUNX2 and ALP. Moreover, we investigated the potential role of OSA in vivo using the SONFH animal model. At concentrations below 100 μM, OSA exhibits no toxicity on vascular endothelial cells and effectively reverses glucocorticoid-induced apoptosis in these cells. OSA increases the resilience of vascular endothelial cells against oxidative stress and enhances osteoblast differentiation. Our study revealed that glucocorticoids activate endoplasmic reticulum stress, a process that mediates the apoptosis of vascular endothelial cells. OSA ameliorated the endoplasmic reticulum stress associated with glucocorticoids through the increased expression of p-Akt levels. In vivo, OSA treatment effectively improved SONFH by enhancing vascular endothelial cell function and promoting osteogenic differentiation. OSA counteracted the adverse effects of glucocorticoids both in vitro and in vivo, demonstrating a beneficial therapeutic effect on SONFH.

Transcription Factor EB: A Promising Therapeutic Target for Ischemic Stroke

Transcription factor EB (TFEB) is an important endogenous defensive protein that responds to ischemic stimuli. Acute ischemic stroke is a growing concern due to its high morbidity and mortality. Most survivors suffer from disabilities such as numbness or weakness in an arm or leg, facial droop, difficulty speaking or understanding speech, confusion, impaired balance or coordination, or loss of vision. Although TFEB plays a neuroprotective role, its potential effect on ischemic stroke remains unclear. This article describes the basic structure, regulation of transcriptional activity, and biological roles of TFEB relevant to ischemic stroke. Additionally, we explore the effects of TFEB on the various pathological processes underlying ischemic stroke and current therapeutic approaches. The information compiled here may inform clinical and basic studies on TFEB, which may be an effective therapeutic drug target for ischemic stroke.

Role of calpain-5 in cerebral ischemia and reperfusion injury

BACKGROUND

Ischemia and reperfusion (I/R) injury exacerbate the prognosis of ischemic diseases. The cause of this exacerbation is partly a mitochondrial cell death pathway. Mitochondrial calpain-5 is proteolyzed/autolyzed under endoplasmic reticulum stress, resulting in inflammatory caspase-4 activation. However, the role of calpain-5 in I/R injury remains unclear. We hypothesized that calpain-5 is involved in ischemic brain disease.

METHODS

Mitochondria from C57BL/6J mice were extracted via centrifugation with/without proteinase K treatment. The expression and proteolysis/autolysis of calpain-5 were determined using western blotting. The mouse and human brains with I/R injury were analyzed using hematoxylin and eosin staining and immunohistochemistry. HT22 cells were treated with tunicamycin and CAPN5 siRNA.

RESULTS

Calpain-5 was expressed in the mitochondria of mouse tissues. Mitochondrial calpain-5 in mouse brains was responsive to calcium earlier than cytosolic calpain-5 in vitro calcium assays and in vivo bilateral common carotid artery occlusion model mice. Immunohistochemistry revealed that neurons were positive for calpain-5 in the normal brains of mice and humans. The expression of calpain-5 was increased in reactive astrocytes at human infarction sites. The knockdown of calpain-5 suppressed of cleaved caspase-11.

CONCLUSIONS

The neurons of human and mouse brains express calpain-5, which is proteolyzed/autolyzed in the mitochondria in the early stage of I/R injury and upregulated in reactive astrocytes in the end-stage.

GENERAL SIGNIFICANCE

Our results provide a comprehensive understanding of the mechanisms underlying I/R injury. Targeting the expression or activity of mitochondrial calpain-5 may suppress the inflammation during I/R injuries such as cerebrovascular diseases.

GPNMB Modulates Autophagy to Enhance Functional Recovery After Spinal Cord Injury in Rats

Spinal cord injury (SCI) severely affects the quality of life and autonomy of patients, and effective treatments are currently lacking. Autophagy, an essential cellular metabolic process, plays a crucial role in neuroprotection and repair after SCI. Glycoprotein non-metastatic melanoma protein B (GPNMB) has been shown to promote neural regeneration and synapse reconstruction, potentially through the facilitation of autophagy. However, the specific role of GPNMB in autophagy after SCI is still unclear. In this study, we utilized the spinal cord transection method to establish SCI rats model and overexpressed GPNMB using adenoviral vectors. We assessed tissue damage using hematoxylin and eosin (H&E) and Nissl staining, and observed cell apoptosis using TUNEL staining. We evaluated the inflammatory response by measuring inflammatory factors using enzyme-linked immunosorbent assay (ELISA). In addition, we measured reactive oxygen species (ROS) levels using 2',7'-dichlorodihydrofluorescein diacetate (DCFH-DA), and assessed oxidative stress levels by measuring malondialdehyde (MDA) and glutathione (GSH) using ELISA. To evaluate autophagy levels, we performed immunofluorescence staining for the autophagy marker Beclin-1 and conducted Western blot analysis for autophagy-related proteins. We also assessed limb recovery through functional evaluation. Meanwhile, we induced cell injury using lipopolysaccharide (LPS) and added an autophagy inhibitor to verify the impact of GPNMB on SCI through autophagy modulation. The results demonstrated that GPNMB alleviated the inflammatory response, reduced oxidative stress levels, inhibited cell apoptosis, and promoted autophagy following SCI. Inhibiting autophagy reversed the effects of GPNMB. These findings suggest that GPNMB promotes neural injury repair after SCI, potentially through attenuating the inflammatory response, reducing oxidative stress, and inhibiting cell apoptosis.

N6-methyladenosine demethylase FTO regulates synaptic and cognitive impairment by destabilizing PTEN mRNA in hypoxic-ischemic neonatal rats

Hypoxic-ischemic brain damage (HIBD) can result in significant global rates of neonatal death or permanent neurological disability. N6-methyladenosine (m6A) modification of RNA influences fundamental aspects of RNA metabolism, and m6A dysregulation is implicated in various neurological diseases. However, the biological roles and clinical significance of m6A in HIBD remain unclear. We currently evaluated the effect of HIBD on cerebral m6A methylation in RNAs in neonatal rats. The m6A dot blot assay showed a global augmentation in RNA m6A methylation post-HI. Herein, we also report on demethylase FTO, which is markedly downregulated in the hippocampus and is the main factor involved with aberrant m6A modification following HI. By conducting a comprehensive analysis of RNA-seq data and m6A microarray results, we found that transcripts with m6A modifications were more highly expressed overall than transcripts without m6A modifications. The overexpression of FTO resulted in the promotion of Akt/mTOR pathway hyperactivation, while simultaneously inhibiting autophagic function. This is carried out by the demethylation activity of FTO, which selectively demethylates transcripts of phosphatase and tensin homolog (PTEN), thus promoting its degradation and reduced protein expression after HI. Moreover, the synaptic and neurocognitive disorders induced by HI were effectively reversed through the overexpression of FTO in the hippocampus. Cumulatively, these findings demonstrate the functional importance of FTO-dependent hippocampal m6A methylome in cognitive function and provides novel mechanistic insights into the therapeutic potentials of FTO in neonatal HIBD.

Seipin overexpression attenuates cerebral ischemia-reperfusion injury via preventing apoptosis and autophagy

BACKGROUND

Ischemic cerebrovascular disease (ICVD) is one of three fatal diseases in humans, along with heart disease and malignant tumors. Cerebral ischemia/reperfusion injury (CI/RI) is the primary cause of ICVD. Recently, seipin was reported to be crucial for lipid droplet formation, hepatic steatosis, and axonal atrophy. However, the function and mechanism of seipin in CI/RI has not been explicitly stated.

METHODS

Oxygen-glucose deprivation/reoxygenation (OGD/R) hippocampal neuron cell line (HT-22) and middle cerebral artery occlusion (MCAO) in rats were established. The levels of apoptosis- and autophagy-related proteins and seipin were confirmed by western blot. Cell proliferation was assessed with CCK-8, and ischemic infarction and pathological structure were monitored by TTC and H&E staining, and tissue apoptosis was assessed through TUNEL assay.

RESULTS

The proliferative activity was decreased, and apoptosis and autophagy pathways could also be induced in the OGD/R HT-22 cells. Seipin overexpression accelerated viability and inhibited apoptosis and autophagy in the OGD/R HT-22 cells. Moreover, the data revealed that seipin overexpression could also attenuate cerebral infarction, apoptosis. Autophagy pathways could be repressed by seipin in the MCAO rats.

CONCLUSION

Seipin has a protective role against CI/RI in rats, and its mechanism might be relevant to the suppression of apoptosis and autophagy, suggesting that seipin might be a latent target for CI/RI.

The environmental enrichment ameliorates chronic cerebral hypoperfusion-induced cognitive impairment by activating autophagy signaling pathway and improving synaptic function in hippocampus

BACKGROUND

Chronic cerebral hypoperfusion (CCH) is a frequently observed underlying pathology of both Alzheimer's disease (AD) and vascular dementia (VD), which is a common consequence of cerebral blood flow (CBF) dysregulation. Synaptic damage has been proven as a crucial causative factor for CCH-related cognitive impairment. This study aimed to investigate the neuroprotective impact of environmental enrichment (EE) intervention on CCH-induced synaptic destruction and the consequent cognitive impairment. Furthermore, the underlying mechanism of this neuroprotective effect was explored to provide new insights into therapeutic interventions for individuals suffering from AD or VD.

METHODS

In this experiment, all rats were initially acclimatized to a standard environment (SE) for a period of one week. On the seventh day, rats underwent either bilateral common carotid artery occlusion (2VO) surgery or sham surgery (Sham) before being subjected to a four-week procedure of exposure to an EE, except for the control group. During the EE or SE procedure, intraperitoneal injection of chloroquine (CQ) into rats was performed once daily for four weeks. Following this, cognitive function was assessed using the Morris water maze (MWM) test. The synapse ultrastructure was subsequently observed using transmission electron microscopy. Expression levels of autophagy-related proteins (LC3, LAMP1, and P62) and synapse-related proteins (Synapsin I and PSD-95) were detected through Western blotting. Finally, immunofluorescence was used to examine the expression levels of Synapsin I and PSD-95 and the colocalization of LAMP-1 and LC3 in the hippocampus.

RESULTS

After undergoing 2VO, rats exposed to SE exhibited cognitive impairment, autophagic dysfunction, and synapse damage. The synapse damage was evidenced by ultrastructural damage and degradation of synapse-related proteins. However, these effects were significantly mitigated by exposure to an EE intervention. Moreover, the intervention led to an improvement in autophagic dysfunction.

CONCLUSION

The study found that EE had a positive impact on CCH-induced synaptic damage. Specifically, EE was found to increase synaptic plasticity-associated proteins and postsynaptic density thickness, while decreasing synaptic space. This multifaceted effect resulted in an amelioration of CCH-induced cognitive impairment. It was shown that this beneficial outcome was mediated via the activation of the autophagy-lysosomal pathway. Overall, the findings suggest that EE may have a therapeutic potential for cognitive impairments associated with CCH through autophagy-mediated synaptic improvement.

Lysosome-targeted fluorescent probes: Design mechanism and biological applications

As an integral organelle in the eukaryote, the lysosome is the degradation center and metabolic signal center in living cells, and partakes in significant physiological processes such as autophagy, cell death and cellular senescence. Fluorescent probe has become a favorite tool for studying organelles and their chemical microenvironments because of its high specificity and non-destructive merits. Over recent years, it has been reported that increasingly new lysosome-targeted probes play a major role in the diagnosis and monitor of diseases, in particular cancer and neurodegenerative diseases. In order to deepen the relevant research on lysosome, it is challenging and inevitability to design novel lysosomal targeting probes. This review first introduces the concepts of lysosome and its closely related biological activities, and then introduces the fluorescent probes for lysosome in detail according to different detection targets, including targeting mechanism, biological imaging, and application in diseases. Finally, we summarize the specific challenges and discuss the future development direction facing the current lysosome-targeted fluorescent probes. We hope that this review can help biologists grasp the application of fluorescent probes and broaden the research ideas of researchers targeting fluorescent probes so as to design more accurate and functional probes for application in diseases.

Signaling pathways in brain ischemia: Mechanisms and therapeutic implications

Ischemic stroke occurs when the arteries supplying blood to the brain are narrowed or blocked, inducing damage to brain tissue due to a lack of blood supply. One effective way to reduce brain damage and alleviate symptoms is to reopen blocked blood vessels in a timely manner and reduce neuronal damage. To achieve this, researchers have focused on identifying key cellular signaling pathways that can be targeted with drugs. These pathways include oxidative/nitrosative stress, excitatory amino acids and their receptors, inflammatory signaling molecules, metabolic pathways, ion channels, and other molecular events involved in stroke pathology. However, evidence suggests that solely focusing on protecting neurons may not yield satisfactory clinical results. Instead, researchers should consider the multifactorial and complex mechanisms underlying stroke pathology, including the interactions between different components of the neurovascular unit. Such an approach is more representative of the actual pathological process observed in clinical settings. This review summarizes recent research on the multiple molecular mechanisms and drug targets in ischemic stroke, as well as recent advances in novel therapeutic strategies. Finally, we discuss the challenges and future prospects of new strategies based on the biological characteristics of stroke.

Phenothiazines reduced autophagy in ischemic stroke through endoplasmic reticulum (ER) stress-associated PERK-eIF2α pathway

BACKGROUND

Neuroprotective effects have been the main focus of new treatment modalities for ischemic stroke. Phenothiazines, or chlorpromazine plus promethazine (C + P), are known to prevent the generation of free radicals and uptake of Ca2+ by plasma membrane; they have a potential as a treatment for acute ischemic stroke (AIS). This study aims to investigate the role of endoplasmic reticulum (ER) stress-associated PERK-eIF2α pathway underlying the phenothiazine-induced neuroprotective effects after cerebral ischemia/reperfusion (I/R) injury.

METHODS

A total of 49 male Sprague Dawley rats (280-320 g) were randomly divided into 4 groups (n = 7 per group): (1) sham, (2) I/R that received 2 h of middle cerebral artery occlusion (MCAO), followed by 6 or 24 h of reperfusion, (3) MCAO treated by C + P without temperature control and (4) MCAO treated by C + P with temperature control. Human neuroblastoma (SH-SY5Y) cells were used in 5 groups: (1) control, (2) oxygen-glucose deprivation (OGD) for 2 h followed by reoxygenation (OGD/R), (3) OGD/R with C + P; (4) OGD/R with PERK inhibitor, GSK2656157, and (5) OGD/R with C + P and GSK2656157. The molecules of ER stress, unfolded protein response (UPR) (Bip, PERK, p-PERK, p-PERK/PERK, eIF2α, p-eIF2α, p-eIF2α/eIF2α), autophagy (ATG12, LC3II/I), and apoptosis (BAX, Bcl-XL) were measured at mRNA levels by real time PCR and protein levels by Western blotting.

RESULTS

In ischemic rats followed by reperfusion, expression of Bip, p-PERK/PERK, p-eIF2α/eIF2α, ATG12, and LC3II/I, as well as BAX were all significantly increased. These markers were significantly reduced by C + P at both 6 and 24 h of reperfusion. Anti-apoptotic Bcl-XL expression was increased, while pro-apoptotic BAX expression was decreased by C + P. In SH-SY5Y cell lines, both C + P and GSK2656157 significantly reduced the level of autophagy and apoptosis after I/R, respectively. The combination of GSK2656157 and C + P did not promote the same effect, suggesting that C + P did not induce any neuroprotective effect by inhibiting autophagy and apoptosis through the PERK-eIF2α pathway when this pathway was already blocked by GSK2656157. In general, the reduction in body temperature by phenothiazines was associated with better neuroprotection but it did not reach significant levels.

CONCLUSION

The combined treatment of C + P plays a crucial role in stroke therapy by inhibiting ER stress-mediated autophagy, thereby leading to reduced apoptosis and increased neuroprotection. Our findings highlight the PERK-eIF2α pathway as a central mechanism through which C + P exerts its beneficial effects. The results from this study may pave the way for the development of more targeted and effective treatments for stroke patients.

TSPO exacerbates acute cerebral ischemia/reperfusion injury by inducing autophagy dysfunction

Autophagy is considered a double-edged sword, with a role in the regulation of the pathophysiological processes of the central nervous system (CNS) after cerebral ischemia-reperfusion injury (CIRI). The 18-kDa translocator protein (TSPO) is a highly conserved protein, with its expression level in the nervous system closely associated with the regulation of pathophysiological processes. In addition, the ligand of TSPO reduces neuroinflammation in brain diseases, but the potential role of TSPO in CIRI is largely undiscovered. On this basis, we investigated whether TSPO regulates neuroinflammatory response by affecting autophagy in microglia. In our study, increased expression of TSPO was detected in rat brain tissues with transient middle cerebral artery occlusion (tMCAO) and in BV2 microglial cells exposed to oxygen-glucose deprivation or reoxygenation (OGD/R) treatment, respectively. In addition, we confirmed that autophagy was over-activated during CIRI by increased expression of autophagy activation related proteins with Beclin-1 and LC3B, while the expression of p62 was decreased. The degradation process of autophagy was inhibited, while the expression levels of LAMP-1 and Cathepsin-D were significantly reduced. Results of confocal laser microscopy and transmission electron microscopy (TEM) indicated that autophagy flux was disordered. In contrast, inhibition of TSPO prevented autophagy over-activation both in vivo and in vitro. Interestingly, suppression of TSPO alleviated nerve cell damage by reducing reactive oxygen species (ROS) and pro-inflammatory factors, including TNF-α and IL-6 in microglia cells. In summary, these results indicated that TSPO might affect CIRI by mediating autophagy dysfunction and thus might serve as a potential target for ischemic stroke treatment.

Autophagy Modulation and Its Implications on Glioblastoma Treatment

Autophagy is a vital cellular process that functions to degrade and recycle damaged organelles into basic metabolites. This allows a cell to adapt to a diverse range of challenging conditions. Autophagy assists in maintaining homeostasis, and it is tightly regulated by the cell. The disruption of autophagy has been associated with many diseases, such as neurodegenerative disorders and cancer. This review will center its discussion on providing an in-depth analysis of the current molecular understanding of autophagy and its relevance to brain tumors. We will delve into the current literature regarding the role of autophagy in glioma pathogenesis by exploring the major pathways of JAK2/STAT3 and PI3K/AKT/mTOR and summarizing the current therapeutic interventions and strategies for glioma treatment. These treatments will be evaluated on their potential for autophagy induction and the challenges associated with their utilization. By understanding the mechanism of autophagy, clinical applications for future therapeutics in treating gliomas can be better targeted.

Dexmedetomidine Ameliorates Cardiac Ischemia/Reperfusion Injury by Enhancing Autophagy Through Activation of the AMPK/SIRT3 Pathway

Objective

Myocardial ischemia-reperfusion (I/R) injury is a detrimental disease, resulting in high morbidity and mortality globally. In this study, we aimed to investigate the role of Dex in mitigating cardiac I/R injury.

Methods

H9c2 cells were treated with Dex (1 μM) for 24 h followed by oxygen-glucose deprivation/re-oxygenation (OGD/R). ANP and BNP mRNA of H9c2 cells and the LDH release were measured. Apoptosis of H9c2 cells was analyzed by flow cytometry. Mitochondrial membrane potential and superoxide production were detected by JC-1 staining and MitoSOXTM Red, respectively. Cell aerobic respiration was measured using Seahorse analysis. In vivo, mice were injected with Dex (25 μg/kg, i.p., once daily) for 5 days and then subjected to heart I/R. Heart function was analyzed by echocardiography. CK-MB and LDH were measured by Elisa. Infarct size was measured using TTC-Evans blue staining. Mitochondrial ultrastructure was observed using transmission electron microscopy. DHE staining, SOD activity, the content of MDA, and the content of GSH/GSSG of heart were measured to evaluate the oxidative stress. In addition, inflammatory cytokines were measured in vivo and in vitro. Furthermore, AMPK, SIRT3, and autophagy-related protein expression in the heart were detected by Western blot.

Results

Dex reduced the H9c2 cells injury exposed to OGD/R, accompanied by improved mitochondrial function and membrane potential. In vivo, Dex improved heart function, myocardial injury, and the mitochondria ultrastructure following I/R injury. Meanwhile, Dex inhibited myocardial oxidative stress and inflammation in the myocardial I/R. Furthermore, Compound C (an AMPK inhibitor) could inhibit Dex-induced autophagy in the I/R heart and the 3-MA (an autophagy inhibitor) could partially interfere with the effects of Dex on the protection of I/R heart.

Conclusion

Dex suppressed oxidative stress and inflammation by promoting autophagy through activating the AMPK/SIRT3 pathway, thus protecting the heart against the I/R injury.

Tat-NTS peptide protects neurons against cerebral ischemia-reperfusion injury via ANXA1 SUMOylation in microglia

Rationale: Recent studies indicate that microglial activation and the resulting inflammatory response could be potential targets of adjuvant therapy for ischemic stroke. Many studies have emphasized a well-established function of Annexin-A1 (ANXA1) in the immune system, including the regulation of microglial activation. Nevertheless, few therapeutic interventions targeting ANXA1 in microglia for ischemic stroke have been conducted. In the present study, Tat-NTS, a small peptide developed to prevent ANXA1 from entering the nucleus, was utilized. We discovered the underlying mechanism that Tat-NTS peptide targets microglial ANXA1 to protect against ischemic brain injury. Methods: Preclinical studies of ischemic stroke were performed using an oxygen-glucose deprivation and reperfusion (OGD/R) cell model in vitro and the middle cerebral artery occlusion (MCAO) animal model of ischemic stroke in vivo. Confocal imaging and 3D reconstruction analyses for detecting the protein expression and subcellular localization of microglia in vivo. Co-immunoprecipitation (Co-IP), immunoblotting, ELISA, quantitative real-time PCR (qRT-PCR), Luciferase reporter assay for determining the precise molecular mechanism. Measurement on the cytotoxicity of Tat-NTS peptide for microglia was assessed by CCK-8 and LDH assay. TUNEL staining was used to detect the microglia conditioned medium-mediated neuronal apoptosis. Adeno-associated viruses (AAVs) were injected into the cerebral cortex, striatum and hippocampal CA1 region of adult male Cx3cr1-Cre mice, to further verify the neurofunctional outcome and mechanism of Tat-NTS peptide by TTC staining, the modified Neurological Severity Score (mNSS) test, the open field test (OFT), the novel object recognition task (NORT), the Morris water maze (MWM) test, the long-term potentiation (LTP) and the Transmission electron microscopy (TEM). Results: It was observed that administration of Tat-NTS led to a shift of subcellular localization of ANXA1 in microglia from the nucleus to the cytoplasm in response to ischemic injury. Notably, this shift was accompanied by an increase in ANXA1 SUMOylation in microglia and a transformation of microglia towards an anti-inflammatory phenotype. We confirmed that Tat-NTS-induced ANXA1 SUMOylation in microglia mediated IKKα degradation via NBR1-dependent selective autophagy, then blocking the activation of the NF-κB pathway. As a result, the expression and release of the pro-inflammatory factors IL-1β and TNF-α were reduced in both in vitro and in vivo experiments. Furthermore, we found that Tat-NTS peptide's protective effect on microglia relieved ischemic neuron apoptosis. Finally, we demonstrated that Tat-NTS peptide administration, through induction of ANXA1 SUMOylation in microglia, reduced infarct volume, improved neurological function and facilitated behavioral recovery in MCAO mice. Conclusions: Our study provides evidence for a novel mechanism of Tat-NTS peptide in regulating microglial ANXA1 function and its substantial neuroprotective effect on neurons with ischemic injuries. These findings suggest that Tat-NTS peptides have a high potential for clinical application and may be a promising therapeutic candidate for treating cerebral ischemia.

Nrf2/HO-1 blocks TXNIP/NLRP3 interaction via elimination of ROS in oxygen-glucose deprivation-induced neuronal necroptosis

Acute ischemic stroke (AIS) is known to trigger a cascade of inflammatory events that induces secondary tissue damages. As a type of regulated inflammatory cell death, necroptosis is associated with AIS, whilst its regulation during neuroinflammation is not well understood. In particular, the actual function of NOD-like-receptor family pyrin domain-containing-3(NLRP3) inflammasome in cortical neuronal necroptosis still not clear. Herein, we explored the function of nuclear factor erythroid-2 related factor-2 (Nrf2)/heme oxygenase-1 (HO-1) in oxygen-glucose deprivation (OGD) induced neuronal necroptosis and its underlying mechanism. To establish an in vitro model of neuronal necrosis, we used OGD/caspase-8 inhibitors (Q-VD-OPh, QVD) to treat rat primary cortical neurons (PCNs) after reoxygenation, wherein we found that the model cause an elevated ROS levels by mediating TXNIP/NLRP3 interactions, which in turn activated the NLRP3 inflammasome. Also, we observed that regulation of nuclear factor erythroid-2 related factor-2 (Nrf2) promoted heme oxygenase-1 (HO-1) expression and decreased TXNIP (a protein that relate oxidative stress to activation of inflammasome) and ROS levels, which negatively regulated the expression of OGD-induced activation of NLRP3 inflammasomes. In addition, HO-1 weakened NLRP3 inflammation body activation, which suggests that Nrf2-regulated HO-1 could block the interaction between TXNIP and NLRP3 in OGD/R-treated cortical neurons by inhibiting ROS production. Our study has discovered the importance of Nrf2/HO-1 signaling cascade for inhibiting inflammasome of NLRP3, which negatively regulated necrosis. Therefore, NLRP3 is considered a potential target for a novel neuroprotective approach, which can expand the therapeutic windows of stroke drugs.

Reinventing the Penumbra - the Emerging Clockwork of a Multi-modal Mechanistic Paradigm

The concept of the ischemic penumbra was originally defined as the area around a necrotic stroke core and seen as the tissue at imminent risk of further damage. Today, the penumbra is generally considered as time-sensitive hypoperfused brain tissue with decreased oxygen and glucose availability, salvageable tissue as treated by intervention, and the potential target for neuroprotection in focal stroke. The original concept entailed electrical failure and potassium release but one short of neuronal cell death and was based on experimental stroke models, later confirmed in clinical imaging studies. However, even though the basic mechanisms have translated well, conferring brain protection, and improving neurological outcome after stroke based on the pathophysiological mechanisms in the penumbra has yet to be achieved. Recent findings shape the modern understanding of the penumbra revealing a plethora of molecular and cellular pathophysiological mechanisms. We now propose a new model of the penumbra, one which we hope will lay the foundation for future translational success. We focus on the availability of glucose, the brain's central source of energy, and bioenergetic failure as core pathophysiological concepts. We discuss the relation of mitochondrial function in different cell types to bioenergetics and apoptotic cell death mechanisms, autophagy, and neuroinflammation, to glucose metabolism in what is a dynamic ischemic penumbra.

Tricin promoted ATG-7 dependent autophagic degradation of α-synuclein and dopamine release for improving cognitive and motor deficits in Parkinson's disease

Tricin, a natural nontoxic flavonoid distributed in grasses and euphorbia plants, has been reported to scavenge free radicals, possess anti-inflammatory and antioxidative effects. However, its autophagic effect on Parkinson's disease (PD) has not been elucidated. By adopting cellular and C. elegans models of PD, the autophagic effect of tricin was identified based on the level of autophagy markers (LC3-II and p62). Besides, the pharmacological effects on neurotransmitters (dopamine), inflammatory cytokines (IFN γ, TNFα, MCP-1, IL-10, IL-6 and IL-17A), histology (hematoxylin & eosin and Nissl staining) and behavioural pathology (open-field test, hindlimb clasping, Y-maze, Morris water-maze and nest building test) were also confirmed in the A53T-α-synuclein transgenic PD mouse model. Further experiments demonstrated that tricin induced autophagic flux and lowered the level of α-synuclein through AMPK-p70s6K- and ATG7-dependent mechanism. Compared to the existing clinical PD drugs, tricin mitigated pathogenesis and symptoms of PD with no observable side effects. In summary, tricin is proposed as a potential adjuvant remedy or nutraceutical for the prevention and treatment of PD.

Targeted Energy Metabolomics Combined with Spatial Metabolomics Study on the Efficacy of Guhong Injection Against Cerebral Ischemia Reperfusion

Optimizing the metabolic phenotype to improve cerebral function is critical for treatment of cerebral ischemia-reperfusion (I/R) injury. Guhong injection (GHI), which comprised safflower extract and aceglutamide, is widely prescribed in Chinese medicine for the treatment of cerebrovascular diseases. In this study, a combination of LC-QQQ-MS and MALDI-MSI were utilized to explore tissue-specific metabolic alterations in the brain of I/R, as well as to evaluate the therapeutic effect of GHI. Pharmacological evaluation demonstrated that GHI can significantly improve infarction rate, neurological deficit, cerebral blood flow, and neuronal damage in I/R rats. Based on LC-QQQ-MS, 23 energy metabolites were found to be significantly altered in the I/R group compared to the sham group (P < 0.05). After GHI treatment, 12 metabolites, including G6P, TPP, NAD, citrate, succinate, malate, ATP, GTP, GDP, ADP, NADP, and FMN showed a significant tendency of returning to baseline values (P < 0.05). Based on MALDI-MSI, 4 metabolites in glycolysis and TCA, 4 metabolites in nucleic acid metabolism, 4 amino acid metabolites, and 6 metabolites were discovered and compared between the different groups in the four special regions of cortex, hippocampus, hypothalamus, and striatum. Parts of these were found to have significant changes after I/R in the special brain region, and were regulated by GHI. The study provides comprehensive and detailed information for specific metabolic reprogramming of brain tissue in rats with I/R, and the therapeutic effect of GHI. Schema describing the discovery strategies of integrated LC-MS and MALDI-MSI to identify cerebral ischemia reperfusion metabolic reprogramming and GHI therapeutic effects.

Identifying Serum Metabolites and Gut Bacterial Species Associated with Nephrotoxicity Caused by Arsenic and Fluoride Exposure

Co-contamination of arsenic (As) and fluoride (F) is widely distributed in groundwater, which are known risk factors for the nephrotoxicity. Emerging evidence has linked environmentally associated nephrotoxicity with the disturbance of gut microbiota and blood metabolites. In this study, we generated gut microbiota and blood metabolomic profile and identified multiple serum metabolites and gut bacteria species, which were associated with kidney injury on rat model exposed to As and F alone or combined. Combined As and F exposure significantly increased creatinine level. Abnormal autophagosomes and lysosome were observed, and the autophagic genes were enhanced in kidney tissue after single and combined As and F exposure. The metabolome data showed that single and combined As and F exposure remarkably altered the serum metabolites associated with the proximal tubule reabsorption function pathway, with glutamine and alpha-ketoglutarate level decreased in all exposed group. Furthermore, phosphatidylethanolamine (PE), the key contributor of autophagosomes, was decreased significantly in As and F + As exposed groups during the screen of autophagy-animal pathway. Multiple altered gut bacterial microbiota at phylum and species levels post As and F exposure were associated with targeted kidney injury, including p_Bacteroidetes, s_Chromohalobacter_unclassified, s_Halomonas_unclassified, s_Ignatzschineria_unclassified, s_Bacillus_subtilis, and s_Brevundimonas_sp._NA6. Meanwhile, our analysis indicated that As and F co-exposure possessed an interactive influence on gut microbiota. In conclusion, single or combined As and F exposure leads to the disruption of serum metabolic and gut microbiota profiles. Multiple metabolites and bacterial species are identified and associated with nephrotoxicity, which have potential to be developed as biomarkers of As and/or F-induced kidney damage.

The Pathological Mechanism of Neuronal Autophagy-Lysosome Dysfunction After Ischemic Stroke

The abnormal initiation of autophagy flux in neurons after ischemic stroke caused dysfunction of autophagy-lysosome, which not only led to autophagy flux blockage, but also resulted in autophagic death of neurons. However, the pathological mechanism of neuronal autophagy-lysosome dysfunction did not form a unified viewpoint until now. In this review, taking the autophagy lysosomal dysfunction of neurons as a starting point, we summarized the molecular mechanisms that led to neuronal autophagy lysosomal dysfunction after ischemic stroke, which would provide theoretical basis for the clinical treatment of ischemic stroke.

Dihydromyricetin Alleviates Ischemic Brain Injury by Antagonizing Pyroptosis in Rats

Ischemic stroke is a worldwide disease that seriously threatens human health, and there are few effective drugs to treat it. Dihydromyricetin (DHM) has anti-inflammatory, antioxidant, and antiapoptotic functions. We identified pyroptosis following ischemic stroke. Here, we investigated the effect of DHM on ischemic stroke and pyroptosis. In the first part of the experiment, Sprague-Dawley rats were randomly divided into the sham group and MCAO group. The MCAO model was established by occlusion of the middle cerebral artery for 90 min using a silica gel suture. The ischemic penumbra was used for mRNA sequencing 1 day after reperfusion. In the second part, rats were divided into the sham group, MCAO group, and DHM group. DHM was injected intraperitoneally at the same time as reperfusion starting 90 min after embolization for 7 consecutive days. The changes in pyroptosis were observed by morphological and molecular methods. The transcriptomics results suggested the presence of NLRP3-mediated pyroptotic death pathway activation after modeling. The Longa score was increased after MCAO and decreased after DHM treatment. 2,3,5-Triphenyltetrazolium chloride (TTC) staining showed that DHM could reduce the infarct volume induced by MCAO. Nissl staining showed disordered neuronal arrangement and few Nissl bodies in the MCAO group, but this effect was reversed by DHM treatment. Analysis of pyroptosis-related molecules showed that the MCAO group had serious pyroptosis, and DHM effectively reduced pyroptosis. Our results demonstrate that DHM has a neuroprotective effect on ischemic stroke that is at least partly achieved by reducing pyroptosis.

Ginkgo biloba extract (EGb-761) confers neuroprotection against ischemic stroke by augmenting autophagic/lysosomal signaling pathway

Ginkgo biloba extract (EGb-761) is well-recognized to have neuroprotective properties. Meanwhile, autophagy machinery is extensively involved in the pathophysiological processes of ischemic stroke. The EGb-761 is widely used in the clinical treatment of stroke patients. However, its neuroprotective mechanisms against ischemic stroke are still not fully understood. The present study was conducted to uncover whether the pharmacological effects of EGb-761 can be executed by modulation of the autophagic/lysosomal signaling axis. A Sprague-Dawley rat model of ischemic stroke was established by middle cerebral artery occlusion (MCAO) for 90 min, followed by reperfusion. The EGb-761 was then administered to the MCAO rats once daily for a total of 7 days. Thereafter, the penumbral tissues were acquired to detect proteins involved in the autophagic/lysosomal pathway including Beclin1, LC-3, SQSTM1/p62, ubiquitin, cathepsin B, and cathepsin D by western blot and immunofluorescence, respectively. Subsequently, the therapeutic outcomes were evaluated by measuring the infarct volume, neurological deficits, and neuron survival. The results showed that the autophagic activities of Beclin1 and LC3-II in neurons were markedly promoted by 7 days of EGb-761 therapy. Meanwhile, the autophagic cargoes of insoluble p62 and ubiquitinated proteins were effectively degraded by EGb-761-augmented lysosomal activity of cathepsin B and cathepsin D. Moreover, the infarction size, neurological deficiencies, and neuron death were also substantially attenuated by EGb-761 therapy. Taken together, our study suggests that EGb-761 exerts a neuroprotective effect against ischemic stroke by promoting autophagic/lysosomal signaling in neurons at the penumbra. Thus, it might be a new therapeutic target for treating ischemic stroke.

Microglial LRRK2-mediated NFATc1 attenuates α-synuclein immunotoxicity in association with CX3CR1-induced migration and the lysosome-initiated degradation

Synucleinopathies refer to a range of neurodegenerative diseases caused by abnormal α-synuclein (α-Syn) deposition, including Parkinson's disease (PD), dementia with Lewy bodies (DLB), and multiple system atrophy (MSA). Their pathogenesis is strongly linked to microglial dysfunction and neuroinflammation, which involves the leucine-rich-repeat kinase 2 (LRRK2)-regulated nuclear factor of activated T-cells (NFAT). Of the NFAT family, NFATc1 has been found to be increasingly translocated into the nucleus in α-syn stimulation. However, the specific role of NFATc1-mediated intracellular signaling in PD remains elusive in regulating microglial functions. In the current study, we crossbred LRRK2 or NFATc1 conditional knockout mice with Lyz2Cre mice to generate mice with microglia-specific deletion of LRRK2 or NFATc1, and by stereotactic injection of fibrillary α-Syn, we generated PD models in these mice. We found that LRRK2 deficiency enhanced microglial phagocytosis in the mice after α-Syn exposure and that genetic inhibition of NFATc1 markedly diminished phagocytosis and α-Syn elimination. We further demonstrated that LRRK2 negatively regulated NFATc1 in α-Syn-treated microglia, in which microglial LRRK2-deficiency facilitated NFATc1 nuclear translocation, CX3CR1 upregulation, and microglia migration. Additionally, NFATc1 translocation upregulated the expression of Rab7 and promoted the formation of late lysosomes, resulting in α-Syn degradation. In contrast, the microglial NFATc1 deficiency impaired CX3CR1 upregulation and the formation of Rab7-mediated late lysosomes. These findings highlight the critical role of NFATc1 in modulating microglial migration and phagocytosis, in which the LRRK2-NFATc1 signaling pathway regulates the expression of microglial CX3CR1 and endocytic degradative Rab7 to attenuate α-synuclein immunotoxicity.

Astrocytic AT1R deficiency ameliorates Aβ-induced cognitive deficits and synaptotoxicity through β-arrestin2 signaling

Alzheimer's disease (AD) seriously influences human health, and there is no effective treatment to prevent or cure AD. Recent studies have shown that angiotensin II type 1 receptor (AT1R) blockers significantly reduce the prevalence of AD, while the precise role and mechanism of AT1R in AD remain obscure. In this study, for the first time, we identified that astrocytic but not neuronal AT1R levels were significantly increased in AD model rats and found that astrocyte-specific knockout of AT1R significantly ameliorated amyloid β (Aβ)-induced cognitive deficits and synaptotoxicity. Pretreating astrocytes with an AT1R blocker also alleviated Aβ-induced synaptotoxicity in the coculture system of hippocampal neurons and astrocytes. Moreover, AT1R could directly bind to Aβ1-42 and activate the astrocytic β-arrestin2 pathway in a biased manner, and biased inhibition of the astrocytic AT1R/β-arrestin2 pathway relieved Aβ-induced neurotoxicity. Furthermore, we demonstrated that astrocytic AT1R/β-arrestin2 pathway-mediated synaptotoxicity was associated with the aggregation of autophagosomes, which triggered the disordered degradation of Aβ. Our findings reveal a novel molecular mechanism of astrocytic AT1R in Aβ-induced neurodegeneration and might contribute to establishing new targets for AD prevention and therapy.

SIRT6 deficiency in endothelial cells exacerbates oxidative stress by enhancing HIF1α accumulation and H3K9 acetylation at the Ero1α promoter

BACKGROUND

SIRT6, an important NAD+ -dependent protein, protects endothelial cells from inflammatory and oxidative stress injuries. However, the role of SIRT6 in cardiac microvascular endothelial cells (CMECs) under ischemia-reperfusion injury (IRI) remains unclear.

METHODS

The HUVECs model of oxygen-glucose deprivation/reperfusion (OGD/R) was established to simulate the endothelial IRI in vitro. Endoplasmic reticulum oxidase 1 alpha (Ero1α) mRNA and protein levels in SIRT6-overexpressing or SIRT6-knockdown cells were measured by qPCR and Western blotting. The levels of H2 O2 and mitochondrial reactive oxygen species (ROS) were detected to evaluate the status of oxidative stress. The effects of SIRT6 deficiency and Ero1α knockdown on cellular endoplasmic reticulum stress (ERS), inflammation, apoptosis and barrier function were detected by a series of molecular biological experiments and functional experiments in vitro. Chromatin immunoprecipitation, Western blotting, qPCR, and site-specific mutation experiments were used to examine the underlying molecular mechanisms. Furthermore, endothelial cell-specific Sirt6 knockout (ecSirt6-/- ) mice were subjected to cardiac ischemia-reperfusion surgery to investigate the effects of SIRT6 in CMECs in vivo.

RESULTS

The expression of Ero1α was significantly upregulated in SIRT6-knockdown endothelial cells, and high Ero1α expression correlated with the accumulation of H2 O2 and mitochondrial ROS. In addition, SIRT6 deficiency increased ERS, inflammation, apoptosis and endothelial permeability, and these effects could be significantly attenuated by Ero1α knockdown. The deacetylase catalytic activity of SIRT6 was important in regulating Ero1α expression and these biological processes. Mechanistically, SIRT6 inhibited the enrichment of HIF1α and p300 at the Ero1α promoter through deacetylating H3K9, thereby antagonizing HIF1α/p300-mediated Ero1α expression. Compared with SIRT6-wild-type (SIRT6-WT) cells, cells expressing the SIRT6-H133Y-mutant and SIRT6-R65A-mutant exhibited increased Ero1α expression. Furthermore, ecSirt6-/- mice subjected to ischemia-reperfusion surgery exhibited increased Ero1α expression and ERS in CMECs and worsened injuries to microvascular barrier function and cardiac function.

CONCLUSIONS

Our results revealed an epigenetic mechanism associated with SIRT6 and Ero1α expression and highlighted the therapeutic potential of targeting the SIRT6-HIF1α/p300-Ero1α axis.

Acrylamide interferes with autophagy and induces apoptosis in Neuro-2a cells by interfering with TFEB-regulated lysosomal function

Acrylamide (ACR), a well-documented human neurotoxicant that is widely exists in starchy foods. More than 30% of human daily energy is provided by ACR-containing foods. Evidence indicated that ACR can induce apoptosis and inhibit autophagy, but the mechanisms are limited. Transcription Factor EB (TFEB) is a major transcriptional regulator of the autophagy-lysosomal biogenesis that regulates autophagy processes and cell degradation. Our study aimed to investigated the potential mechanisms of TFEB-regulated lysosomal function in ACR-caused autophagic flux inhibition and apoptosis in Neuro-2a cells. Our results found that ACR exposure inhibited the autophagic flux, as revealed by the elevated LC3-II/LC3-I and p62 levels and a notable increased autophagosomes. ACR exposure reduced the amounts of LAMP1 and mature cathepsin D and caused an accumulation of ubiquitinated proteins, which suggests lysosomal dysfunction. In addition, ACR increased cellular apoptosis via decreasing Bcl-2 expression, increasing Bax and cleaved caspase-3 expression, and raising the apoptotic rate. Interestingly, TFEB overexpression alleviated the ACR-induced lysosomal dysfunction, and then mitigated the autophagy flux inhibition and cellular apoptosis. On the other hand, TFEB knockdown exacerbated the ACR-induced lysosomal dysfunction, autophagy flux inhibition, and cellular apoptosis. These findings strongly suggested that TFEB- regulated lysosomal function is responsible for ACR-caused autophagic flux inhibition and apoptosis in Neuro-2a cells. The present study hopes to explore new sensitive indicators in the mechanism of ACR neurotoxicity and thus provide new targets for the prevention and treatment of ACR intoxication.

Activation of TLR7-mediated autophagy increases epileptic susceptibility via reduced KIF5A-dependent GABAA receptor transport in a murine model

The pathophysiological mechanisms underlying epileptogenesis are poorly understood but are considered to actively involve an imbalance between excitatory and inhibitory synaptic transmission. Excessive activation of autophagy, a cellular pathway that leads to the removal of proteins, is known to aggravate the disease. Toll-like receptor (TLR) 7 is an innate immune receptor that regulates autophagy in infectious and noninfectious diseases. However, the relationship between TLR7, autophagy, and synaptic transmission during epileptogenesis remains unclear. We found that TLR7 was activated in neurons in the early stage of epileptogenesis. TLR7 knockout significantly suppressed seizure susceptibility and neuronal excitability. Furthermore, activation of TLR7 induced autophagy and decreased the expression of kinesin family member 5 A (KIF5A), which influenced interactions with γ-aminobutyric acid type A receptor (GABAAR)-associated protein and GABAARβ2/3, thus producing abnormal GABAAR-mediated postsynaptic transmission. Our results indicated that TLR7 is an important factor in regulating epileptogenesis, suggesting a possible therapeutic target for epilepsy.

Targeting neuronal mitophagy in ischemic stroke: an update

Cerebral ischemia is a neurological disorder associated with complex pathological mechanisms, including autophagic degradation of neuronal mitochondria, or termed mitophagy, following ischemic events. Despite being well-documented, the cellular and molecular mechanisms underlying the regulation of neuronal mitophagy remain unknown. So far, the evidence suggests neuronal autophagy and mitophagy are separately regulated in ischemic neurons, the latter being more likely activated by reperfusional injury. Specifically, given the polarized morphology of neurons, mitophagy is regulated by different neuronal compartments, with axonal mitochondria being degraded by autophagy in the cell body following ischemia-reperfusion insult. A variety of molecules have been associated with neuronal adaptation to ischemia, including PTEN-induced kinase 1, Parkin, BCL2 and adenovirus E1B 19-kDa-interacting protein 3 (Bnip3), Bnip3-like (Bnip3l) and FUN14 domain-containing 1. Moreover, it is still controversial whether mitophagy protects against or instead aggravates ischemic brain injury. Here, we review recent studies on this topic and provide an updated overview of the role and regulation of mitophagy during ischemic events.

Identification and cross-validation of autophagy-related genes in cardioembolic stroke

Objective

Cardioembolic stroke (CE stroke, also known as cardiogenic cerebral embolism, CCE) has the highest recurrence rate and fatality rate among all subtypes of ischemic stroke, the pathogenesis of which was unclear. Autophagy plays an essential role in the development of CE stroke. We aim to identify the potential autophagy-related molecular markers of CE stroke and uncover the potential therapeutic targets through bioinformatics analysis.

Methods

The mRNA expression profile dataset GSE58294 was obtained from the GEO database. The potential autophagy-related differentially expressed (DE) genes of CE stroke were screened by R software. Protein-protein interactions (PPIs), correlation analysis, and gene ontology (GO) enrichment analysis were applied to the autophagy-related DE genes. GSE66724, GSE41177, and GSE22255 were introduced for the verification of the autophagy-related DE genes in CE stroke, and the differences in values were re-calculated by Student's t-test.

Results

A total of 41 autophagy-related DE genes (37 upregulated genes and four downregulated genes) were identified between 23 cardioembolic stroke patients (≤3 h, prior to treatment) and 23 healthy controls. The KEGG and GO enrichment analysis of autophagy-related DE genes indicated several enriched terms related to autophagy, apoptosis, and ER stress. The PPI results demonstrated the interactions between these autophagy-related genes. Moreover, several hub genes, especially for CE stroke, were identified and re-calculated by Student's t-test.

Conclusion

We identified 41 potential autophagy-related genes associated with CE stroke through bioinformatics analysis. SERPINA1, WDFY3, ERN1, RHEB, and BCL2L1 were identified as the most significant DE genes that may affect the development of CE stroke by regulating autophagy. CXCR4 was identified as a hub gene of all types of strokes. ARNT, MAPK1, ATG12, ATG16L2, ATG2B, and BECN1 were identified as particular hub genes for CE stroke. These results may provide insight into the role of autophagy in CE stroke and contribute to the discovery of potential therapeutic targets for CE stroke treatment.

Neuroglobin protects against cerebral ischemia/reperfusion injury in rats by suppressing mitochondrial dysfunction and endoplasmic reticulum stress-mediated neuronal apoptosis through synaptotagmin-1

Cerebral ischemia/reperfusion (I/R) injury remains a grievous health threat, and herein effective therapy is urgently needed. This study explored the protection of neuroglobin (Ngb) in rats with cerebral I/R injury. The focal cerebral I/R rat models were established by middle cerebral artery occlusion (MCAO) and neuronal injury models were established by oxygen-glucose deprivation/reoxygenation (OGD/R) treatment. The brain injury of rats was assessed. Levels of Ngb, Bcl-2, Bax, endoplasmic reticulum stress (ERS)-related markers, and Syt1 were measured by immunofluorescence staining and Western blotting. The cytotoxicity in neurons was assessed by lactate dehydrogenase (LDH) release assay. Levels of intracellular Ca²⁺ and mitochondrial function-related indicators were determined. The binding between Ngb and Syt1 was detected by co-immunoprecipitation. Ngb was upregulated in cerebral I/R rats and its overexpression alleviated brain injury. In OGD/R-induced neurons, Ngb overexpression decreased LDH level and neuronal apoptosis, decreased Ca²⁺ content, and mitigated mitochondrial dysfunction and ERS-related apoptosis. However, Ngb silencing imposed the opposite effects. Importantly, Ngb could bind to Syt1. Syt1 knockdown partially counteracted the alleviation of Ngb on OGD/R-induced injury in neurons and cerebral I/R injury in rats. Briefly, Ngb extenuated cerebral I/R injury by repressing mitochondrial dysfunction and endoplasmic reticulum stress-mediated neuronal apoptosis through Syt1.

mTOR/α-ketoglutarate signaling: impact on brain cell homeostasis under ischemic conditions

The multifunctional molecules mechanistic target of rapamycin (mTOR) and α-ketoglutarate (αKG) are crucial players in the regulatory mechanisms that maintain cell homeostasis in an ever-changing environment. Cerebral ischemia is associated primarily with oxygen-glucose deficiency (OGD) due to circulatory disorders. Upon exceeding a threshold of resistance to OGD, essential pathways of cellular metabolism can be disrupted, leading to damage of brain cells up to the loss of function and death. This mini-review focuses on the role of mTOR and αKG signaling in the metabolic homeostasis of brain cells under OGD conditions. Integral mechanisms concerning the relative cell resistance to OGD and the molecular basis of αKG-mediated neuroprotection are discussed. The study of molecular events associated with cerebral ischemia and endogenous neuroprotection is relevant for improving the effectiveness of therapeutic strategies.

Autophagy, innate immunity, and cardiac disease

Autophagy is an evolutionarily conserved mechanism of cell adaptation to metabolic and environmental stress. It mediates the disposal of protein aggregates and dysfunctional organelles, although non-conventional features have recently emerged to broadly extend the pathophysiological relevance of autophagy. In baseline conditions, basal autophagy critically regulates cardiac homeostasis to preserve structural and functional integrity and protect against cell damage and genomic instability occurring with aging. Moreover, autophagy is stimulated by multiple cardiac injuries and contributes to mechanisms of response and remodeling following ischemia, pressure overload, and metabolic stress. Besides cardiac cells, autophagy orchestrates the maturation of neutrophils and other immune cells, influencing their function. In this review, we will discuss the evidence supporting the role of autophagy in cardiac homeostasis, aging, and cardioimmunological response to cardiac injury. Finally, we highlight possible translational perspectives of modulating autophagy for therapeutic purposes to improve the care of patients with acute and chronic cardiac disease.

Immortalized Alzheimer's Disease Astrocytes: Characterization of Their Proteolytic Systems

Alzheimer's disease (AD) is a progressive neurodegeneration with dysfunctions in both the ubiquitin-proteasome system (UPS) and autophagy. Astroglia participation in AD is an attractive topic of research, but molecular patterns are partially defined and available in vitro models have technical limitations. Immortalized astrocytes from the hippocampus of 3xTg-AD and wild-type mice (3Tg-iAstro and WT-iAstro, respectively) have been obtained as an attempt to overcome primary cell line limitations and this study aims at characterizing their proteolytic systems, focusing on UPS and autophagy. Both 26S and 20S proteasomal activities were downregulated in 3Tg-iAstro, in which a shift in catalytic subunits from constitutive 20S proteasome to immunoproteasome occurred, with consequences on immune functions. In fact, immunoproteasome is the specific complex in charge of clearing damaged proteins under inflammatory conditions. Parallelly, augmented expression and activity of the lysosomal cathepsin B, enhanced levels of lysosomal-associated membrane protein 1, beclin1, and LC3-II, together with an increased uptake of monodansylcadaverine in autophagic vacuoles, suggested autophagy activation in 3Tg-iAstro. The two proteolytic pathways were linked by p62 that accumulated in 3Tg-iAstro due to both increased synthesis and decreased degradation in the UPS defective astrocytes. Treatment with 4-phenylbutyric acid, a neuroprotective small chemical chaperone, partially restored proteasome and autophagy-mediated proteolysis in 3Tg-iAstro. Our data shed light on the impaired proteostasis in 3Tg-iAstro with proteasome inhibition and autophagic compensatory activation, providing additional validation of this AD in vitro model, and propose a new mechanism of action of 4-phenylbutyric acid in neurodegenerative disorders.

Cellular battle against endoplasmic reticulum stress and its adverse effect on health

The endoplasmic reticulum (ER) is a dynamic organelle and a reliable performer for precisely folded proteins. To maintain its function and integrity, arrays of sensory and quality control systems enhance protein folding fidelity and resolve the highest error-prone areas. Yet numerous internal and external factors disrupt its homeostasis and trigger ER stress responses. Cells try to reduce the number of misfolded proteins via the UPR mechanism, and ER-related garbage disposals systems like ER-associated degradation (ERAD), ER-lysosome-associated degradation (ERLAD), ER-Associated RNA Silencing (ERAS), extracellular chaperoning, and autophagy systems, which activates and increase the cell survival rate by degrading misfolded proteins, prevent the aggregated proteins and remove the dysfunctional organelles. Throughout life, organisms must confront environmental stress to survive and develop. Communication between the ER & other organelles, signaling events mediated by calcium, reactive oxygen species, and inflammation are linked to diverse stress signaling pathways and regulate cell survival or cell death mechanisms. Unresolved cellular damages can cross the threshold limit of their survival, resulting in cell death or driving for various diseases. The multifaceted ability of unfolded protein response facilitates the therapeutic target and a biomarker for various diseases, helping with early diagnosis and detecting the severity of diseases.

Differences in the post-stroke innate immune response between young and old

Aging is associated to progressive changes impairing fundamental cellular and tissue functions, and the relationships amongst them through the vascular and immune systems. Aging factors are key to understanding the pathophysiology of stroke since they increase its risk and worsen its functional outcome. Most currently recognised hallmarks of aging are also involved in the cerebral responses to stroke. Notably, age-associated chronic low-grade inflammation is related to innate immune responses highlighted by induction of type-I interferon. The interferon program is prominent in microglia where it interrelates cell damage, danger signals, and phagocytosis with immunometabolic disturbances and inflammation. Microglia engulfment of damaged myelin and cell debris may overwhelm the cellular capacity for waste removal inducing intracellular lipid accumulation. Acute inflammation and interferon-stimulated gene expression are also typical features of acute stroke, where danger signal recognition by microglia trigger immunometabolic alterations underscored by lipid droplet biogenesis. Aging reduces the capacity to control these responses causing increased and persistent inflammation, metabolic dysregulation, and impaired cellular waste disposal. In turn, chronic peripheral inflammation during aging induces immunosenescence further worsening stroke-induced immunodepression, thus increasing the risk of post-stroke infection. Aging also alters gut microbiota composition inducing dysbiosis. These changes are enhanced by age-related diseases, such as atherosclerosis and type-II diabetes, that further promote vascular aging, predispose to stroke, and exacerbate brain inflammation after stroke. Current advances in aging research suggest that some age-associated alterations may be reversed. Future work will unravel whether such evolving anti-aging research may enable designing strategies to improve stroke outcome in the elderly.