Inhibition of SENP3 by lentivirus induces suppression of apoptosis in experimental subarachnoid hemorrhage in rats

Transcranial Magnetic Stimulation Alleviates Spatial Learning and Memory Impairment by Inhibiting the Expression of SARM1 in Rats with Cerebral Ischemia-Reperfusion Injury

The cognitive impairment resulting from stroke is purported to be associated with impaired neuronal structure and function. Transcranial Magnetic Stimulation (TMS) modulates neuronal or cortical excitability and inhibits cellular apoptosis, thereby enhancing spatial learning and memory in middle cerebral artery occlusion/reperfusion (MCAO/R) rats. In this study, we aimed to investigate whether Sterile alpha and Toll/interleukin receptor motif-containing protein 1 (SARM1), a pivotal Toll-like receptor adaptor molecule and its related mechanisms are involved in the ameliorating effect of TMS on cognitive function post-cerebral ischemia. We evaluated hippocampal injury in MCAO/R rats after one week of treatment with 10-Hz TMS at an early stage. The effect of SARM1 was more effectively assessed through lentivirus-mediated SARM1 overexpression. Various techniques, including FJB staining, HE staining, western blot, immunofluorescence, imunohistochemistry, and transmission electron microscopy, were employed to investigate the molecular biological and morphological alterations of axons, myelin sheaths and apoptosis in the hippocampus. Ultimately, Morris Water Maze was employed to evaluate the spatial learning and memory capabilities of the rats. We observed that TMS significantly reduced the levels of SARM1, NF-κB, and Bax following MCAO/R, while elevating the levels of HSP70, Bcl-2, GAP-43, NF-200, BDNF, and MBP. Overexpression of SARM1 not only reversed the neuroprotective effects induced by TMS but also exacerbated spatial learning and memory impairments in rats. Our results demonstrate that TMS mitigates hippocampal cell apoptosis via the SARM1/HSP70/NF-κB signaling pathway, thus fostering the regeneration of hippocampal axons and myelin sheaths, as well as the improvement of spatial learning and memory.

SENP3 knockdown improves motor and cognitive impairments in the intranasal MPTP rodent model of Parkinson's disease

Several mechanisms underlying Parkinson's disease (PD) remain unclear, and effective treatments are still lacking. The conjugation of the small ubiquitin-like modifier (SUMO), known as SUMOylation, to key proteins in PD has shown potential beneficial effects. Considering that this process is reversed by SUMO-specific proteases (SENPs), this study addressed the effects of increased SUMO-2/3 conjugation, mediated by SENP3 knockdown, in the intranasal 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) rodent model of PD. Two weeks after infusion of the shRNA-containing lentiviral vector into the dorsolateral striatum and one week following intranasal MPTP administration, male Wistar rats were evaluated using cognitive and motor behavioural tests. Infection efficiency was confirmed by detecting GFP expression in the dorsolateral striatum. SENP3 knockdown, verified by Western blotting, resulted in increased SUMO-2/3 conjugation. MPTP-administered rats displayed impairments in both recognition and spatial memories, while SENP3 knockdown prevented these deficits. Rats exposed to MPTP also exhibited motor dysfunction, which was ameliorated by SENP3 knockdown. These findings underscore the involvement of SUMO-2/3 conjugation in PD and its potential as a novel therapeutic target to counteract cognitive and motor impairments induced by neurodegeneration.

Hippocampal SENP3 mediates chronic stress-induced depression-like behaviors by impairing the CREB-BDNF signaling

Impaired signaling between cyclic adenosine monophosphate response element binding protein (CREB) and brain-derived neurotrophic factor (BDNF) in the hippocampus is generally considered to be the cause of depression. The mechanisms underlying the impairment of CREB-BDNF signaling under stress conditions are largely unclear. Small ubiquitin-like modifier (SUMO) specific peptidase 3 (SENP3) is a molecule that can regulate SUMOylation of target proteins related to synaptic plasticity. Its dynamic changes have been reported to be associated with neuronal damage in various models of central nervous disorders such as cerebral ischemia and traumatic brain injury. However, its role in depression is completely unknown. This problem was addressed in the present study. Our results showed that chronic unpredictable stress (CUS) triggered a specific increase in SENP3 expression in the hippocampus of non-stressed mice. Overexpression of SENP3 in the hippocampus of non-stressed mice elicited depression-like behaviors in the tail suspension test, forced swimming test, and sucrose preference test, accompanied by impairment of the CREB-BDNF signaling cascade in the hippocampus. Conversely, genetic silencing of SENP3 in the hippocampus suppressed the development of depression-like behaviors. Furthermore, infusion of SENP3-shRNA into the hippocampus failed to suppress CUS-induced depression-like behaviors when mice received genetic silencing CREB or BDNF in the hippocampus or inhibition of the BDNF receptor by K252a. Taken together, these results suggest that abnormally elevated SENP3 in the hippocampus leads to the development of depression-like behavior by impairing the CREB-BDNF signaling cascade. SENP3 in the hippocampus could be a promising target for the development of new antidepressants.

SENP3-FIS1 axis promotes mitophagy and cell survival under hypoxia

SUMOylation, the covalent attachment of the small ubiquitin-like modifier (SUMO) to target proteins, and its reversal, deSUMOylation by SUMO proteases like Sentrin-specific proteases (SENPs), are crucial for initiating cellular responses to hypoxia. However, their roles in subsequent adaptation processes to hypoxia such as mitochondrial autophagy (mitophagy) remain unexplored. Here, we show that general SUMOylation, particularly SUMO2/3 modification, suppresses mitophagy under both normoxia and hypoxia. Furthermore, we identify deSUMO2/3-ylation enzyme SENP3 and mitochondrial Fission protein 1 (FIS1) as key players in hypoxia-induced mitophagy (HIM), with SUMOylatable FIS1 acting as a crucial regulator for SENP3-mediated HIM regulation. Interestingly, we find that hypoxia promotes FIS1 SUMO2/3-ylation and triggers an interaction between SUMOylatable FIS1 and Rab GTPase-activating protein Tre-2/Bub2/Cdc16 domain 1 family member 17 (TBC1D17), which in turn suppresses HIM. Therefore, we propose a novel SUMOylation-dependent pathway where the SENP3-FIS1 axis promotes HIM, with TBC1D17 acting as a fine-tuning regulator. Importantly, the SENP3-FIS1 axis plays a protective role against hypoxia-induced cell death, highlighting its physiological significance, and hypoxia-inducible FIS1-TBC1D17 interaction is detectable in primary glioma stem cell-like (GSC) cultures derived from glioblastoma patients, suggesting its disease relevance. Our findings not only provide new insights into SUMOylation/deSUMOylation regulation of HIM but also suggest the potential of targeting this pathway to enhance cellular resilience under hypoxic stress.

SUMOylation modulates mitochondrial dynamics in an in vitro rotenone model of Parkinson's disease

SUMOylation is a post-translational modification essential for various biological processes. SUMO proteins bind to target substrates in a three-step enzymatic pathway, which is rapidly reversible by the action of specific proteases, known as SENPs. Studies have shown that SUMOylation is dysregulated in several human disorders, including neurodegenerative diseases that are characterized by the progressive loss of neurons, mitochondrial dysfunction, deficits in autophagy, and oxidative stress. Considering the potential neuroprotective roles of SUMOylation, the aim of this study was to investigate the effects of SENP3 knockdown in H4 neuroglioma cells exposed to rotenone, an in vitro model of cytotoxicity that mimics dopaminergic loss in Parkinson's disease (PD). The current data show that SENP3 knockdown increases SUMO-2/3 conjugates, which is accompanied by reduced levels of the mitochondrial fission protein Drp1 and increased levels of the mitochondrial fusion protein OPA1. Of high interest, SENP3 knockdown prevented rotenone-induced superoxide production and cellular death. Taken together, these findings highlight the importance of SUMOylation in maintaining mitochondrial homeostasis and the neuroprotective potential of this modification in PD.

Protective Effects of Adropin in Experimental Subarachnoid Hemorrhage

PURPOSE

We aimed to investigate early effects of exogenously administered adropin (AD) on neurological function, endothelial nitric oxide synthase (eNOS) expression, nitrite/nitrate levels, oxidative stress, and apoptosis in subarachnoid hemorrhage (SAH).

METHODS

Following intracerebroventricular AD administration (10 µg/5 µl at a rate of 1 µl/min) SAH model was carried out in Sprague-Dawley rats by injection of autologous blood into the prechiasmatic cistern. The effects of AD were assessed 24 h following SAH. The modified Garcia score was employed to evaluate functional insufficiencies. Adropin and caspase-3 proteins were measured by ELISA, while nitrite/nitrate levels, total antioxidant capacity (TAC) and reactive oxygen/nitrogen species (ROS/RNS) were assayed by standard kits. eNOS expression and apoptotic neurons were detected by immunohistochemical analysis.

RESULTS

The SAH group performed notably lower on the modified Garcia score compared to sham and SAH + AD groups. Adropin administration increased brain eNOS expression, nitrite/nitrate and AD levels compared to SHAM and SAH groups. SAH produced enhanced ROS/RNS generation and reduced antioxidant capacity in the brain. Adropin boosted brain TAC and diminished ROS/RNS production in SAH rats and no considerable change amongst SHAM and SAH + AD groups were detected. Apoptotic cells were notably increased in intensity and number after SAH and were reduced by AD administration.

CONCLUSIONS

Adropin increases eNOS expression and reduces neurobehavioral deficits, oxidative stress, and apoptotic cell death in SAH model. Presented results indicate that AD provides protection in early brain injury associated with SAH.

The mechanism and relevant mediators associated with neuronal apoptosis and potential therapeutic targets in subarachnoid hemorrhage

Subarachnoid hemorrhage (SAH) is a dominant cause of death and disability worldwide. A sharp increase in intracranial pressure after SAH leads to a reduction in cerebral perfusion and insufficient blood supply for neurons, which subsequently promotes a series of pathophysiological responses leading to neuronal death. Many previous experimental studies have reported that excitotoxicity, mitochondrial death pathways, the release of free radicals, protein misfolding, apoptosis, necrosis, autophagy, and inflammation are involved solely or in combination in this disorder. Among them, irreversible neuronal apoptosis plays a key role in both short- and long-term prognoses after SAH. Neuronal apoptosis occurs through multiple pathways including extrinsic, mitochondrial, endoplasmic reticulum, p53 and oxidative stress. Meanwhile, a large number of blood contents enter the subarachnoid space after SAH, and the secondary metabolites, including oxygenated hemoglobin and heme, further aggravate the destruction of the blood-brain barrier and vasogenic and cytotoxic brain edema, causing early brain injury and delayed cerebral ischemia, and ultimately increasing neuronal apoptosis. Even there is no clear and effective therapeutic strategy for SAH thus far, but by understanding apoptosis, we might excavate new ideas and approaches, as targeting the upstream and downstream molecules of apoptosis-related pathways shows promise in the treatment of SAH. In this review, we summarize the existing evidence on molecules and related drugs or molecules involved in the apoptotic pathway after SAH, which provides a possible target or new strategy for the treatment of SAH.

Enhancing S-nitrosoglutathione reductase decreases S-nitrosylation of Drp1 and reduces neuronal apoptosis in experimental subarachnoid hemorrhage both in vivo and in vitro

Subarachnoid hemorrhage (SAH) is a hemorrhagic stroke with a high mortality and disability rate. Nitric oxide (NO) can promote blood supply through vasodilation, leading to protein S-nitrosylation. However, the function of S-nitrosylation in neurons after SAH remains unclear. Excessive NO in the pathological state is converted into S-nitrosoglutathione (GSNO) and stored in cells, which leads to high S-nitrosylation of intracellular proteins and causes nitrosative stress. S-nitrosoglutathione reductase (GSNOR) promotes GSNO degradation and protects cells from excessive S-nitrosylation. We conducted an in vivo rat carotid puncture model and an in vitro neuron hemoglobin intervention. The results showed that SAH induction increased NO, GSNO, neuron protein S-nitrosylation, and neuronal apoptosis, while decreasing the level and activity of GSNOR. GSNOR overexpression by lentivirus decreased GSNO but had little effect on NO. GSNOR overexpression also improved short- and long-term neurobehavioral outcomes in rats and alleviated nitrosative stress. Furthermore, GSNOR reduced neuronal apoptosis and played a neuroprotective role by alleviating Drp1 S-nitrosylation, reducing mitochondrial division. Thus, the regulation of GSNOR in early brain injury and neuronal denitrosylation may play an important role in neuroprotection.

The Critical Roles of the SUMO-Specific Protease SENP3 in Human Diseases and Clinical Implications

Post-translational modification by SUMO (small ubiquitin-like modifier) proteins has been shown to regulate a variety of functions of proteins, including protein stability, chromatin organization, transcription, DNA repair, subcellular localization, protein–protein interactions, and protein homeostasis. SENP (sentrin/SUMO-specific protease) regulates precursor processing and deconjugation of SUMO to control cellular mechanisms. SENP3, which is one of the SENP family members, deconjugates target proteins to alter protein modification. The effect of modification via SUMO and SENP3 is crucial to maintain the balance of SUMOylation and guarantee normal protein function and cellular activities. SENP3 acts as an oxidative stress-responsive molecule under physiological conditions. Under pathological conditions, if the SUMOylation process of proteins is affected by variations in SENP3 levels, it will cause a cellular reaction and ultimately lead to abnormal cellular activities and the occurrence and development of human diseases, including cardiovascular diseases, neurological diseases, and various cancers. In this review, we summarized the most recent advances concerning the critical roles of SENP3 in normal physiological and pathological conditions as well as the potential clinical implications in various diseases. Targeting SENP3 alone or in combination with current therapies might provide powerful targeted therapeutic strategies for the treatment of these diseases.

Pentoxifylline Alleviates Early Brain Injury in a Rat Model of Subarachnoid Hemorrhage

BACKGROUND

Subarachnoid hemorrhage (SAH) is a severe cerebrovascular disease frequently caused by ruptured aneurysms. Early brain injury (EBI) is the primary cause of morbidity and mortality in patients diagnosed with SAH and is associated with increased intracranial pressure, decreased cerebral blood flow and cerebral ischemia. Pentoxifylline (PTX) is a methylxanthine derivative clinically proven to improve perfusion in the peripheral microcirculation and has been shown to have neuroprotective effects in brain trauma and global cerebral ischemia in experimental animal models. This study aimed to determine the effect of PTX in experimental SAH, which has not been investigated yet.

METHODS

An experimental SAH model was induced in male Wistar rats by autologous blood injection into the prechiasmatic cistern, and PTX was injected intraperitoneally immediately after SAH. The effects of PTX were evaluated 24 h after SAH via assessing the cerebral ultrastructure via transmission electron microscopy (TEM). Brain edema, blood-brain barrier (BBB) permeability, red blood cell deformability, tumor necrosis factor-alpha (TNF-alpha), nitrite-nitrate levels and apoptotic neuron death were also determined 24 h after SAH. The BBB permeability was measured by Evans blue (EB) extravasation, erythrocyte deformability was determined by filtration technique, and TNF-alpha and reactive nitrogen metobolites were analyzed in brain tissue by ELISA and spectral analysis, respectively. Apoptotic neurons were determined in brain sections by cleaved caspase-3 immunohistochemical analysis, and expression intensity was quantified using image J software.

RESULTS

Cerebral ultrastructure in SAH group animals revealed intense perivascular edema and distortion in the astrocyte foot processes. PTX treatment attenuated structural deterioration due to SAH. Brain water content, BBB permeability, TNF-alpha, nitrite-nitrate levels and apoptotic neuronal death were significantly increased 24 h after SAH and were significantly alleviated by PTX treatment. There was no significant change in red cell deformability after SAH.

CONCLUSIONS

Our results show that PTX reduces brain edema, BBB permeability, TNF-alpha expression, reactive nitrogen metobolites and apopotosis in experimental SAH. Based on our findings we suggest that PTX exerts neuroprotection against SAH-induced EBI, which might be associated with the inhibition of inflammation and apoptotic neuronal cell death.

Intracerebral Hemorrhage, Oxidative Stress, and Antioxidant Therapy

Hemorrhagic stroke is a common and severe neurological disorder and is associated with high rates of mortality and morbidity, especially for intracerebral hemorrhage (ICH). Increasing evidence demonstrates that oxidative stress responses participate in the pathophysiological processes of secondary brain injury (SBI) following ICH. The mechanisms involved in interoperable systems include endoplasmic reticulum (ER) stress, neuronal apoptosis and necrosis, inflammation, and autophagy. In this review, we summarized some promising advances in the field of oxidative stress and ICH, including contained animal and human investigations. We also discussed the role of oxidative stress, systemic oxidative stress responses, and some research of potential therapeutic options aimed at reducing oxidative stress to protect the neuronal function after ICH, focusing on the challenges of translation between preclinical and clinical studies, and potential post-ICH antioxidative therapeutic approaches.