Sarco/endoplasmic reticulum Ca2+ -ATPase 2b mediates oxidation-induced endoplasmic reticulum stress to regulate neuropathic pain

Identification of Potential Intervention Targets Involved in Prior Exercise that Attenuates Peripheral Neuropathic Pain by Integrating Transcriptome and Whole-genome Bisulfite Sequencing Analyses

Changes in DNA methylation and subsequent alterations in gene expression have opened a new direction in research related to the pathogenesis of peripheral neuropathic pain (PNP). This study aimed to reveal epigenetic perturbations underlying DNA methylation in the dorsal root ganglion (DRG) of rats with peripheral nerve injury in response to prior exercise and identify potential target genes involved. Male Sprague-Dawley rats were divided into three groups, namely, chronic constriction injury (CCI) of the sciatic nerve, CCI with prior 6-week swimming training (CCI_Ex), and sham operated (Sham). Mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL) were used as the main observation indicators to evaluate behavioral changes associated with pain. In this study, 6-week swimming training before CCI prevented later chronic pain. In particular, CCI rats with prior exercise showed a significant increase in the MWT and TWL of the injured lateral hind paw compared with CCI rats without exercise on days 14, 21, and 28 after CCI. Whole-genome bisulfite sequencing from the injured lumbar (L4-L6) DRGs on the 28th day after surgery was detected. We also generated DNA methylation maps of the two comparisons (sham group vs. CCI and CCI groups vs. CCI_Ex group), and 396 overlapping differentially methylated region-related genes were found between the two comparisons. Moreover, we integrated RNA sequencing to understand the mechanism by which differential DNA methylation after CCI may influence gene expression. Finally, Ryr1 and Xirp2 were identified through association analysis of two omics and quantitative reverse-transcription polymerase chain reaction, respectively. The methylation levels of Ryr1 and Xirp2 were upregulated with a corresponding increase in their mRNA expression in the DRGs of CCI rats, whereas prior exercise downregulated Ryr1 methylation and restore its expression level. Functional enrichment analysis of both omics found that the calcium signaling pathway was significantly enriched. Therefore, the potential intervention targets (Ryr1 and Xirp2) in L4-L6 DRGs may be involved in prior exercise that attenuates PNP induced by CCI. This study provides crucial insights into the epigenetic regulation of PNP responses to prior exercise.

Linking Circadian Rhythms to Gut-Brain Axis Lipid Metabolism Associated With Endoplasmic Reticulum Stress in Alzheimer's Disease

BACKGROUND

Alzheimer's disease (AD) is characterized by a decline in cognitive, learning, and memory abilities. Neuroinflammation is associated with the spread of tau tangles in the neocortex of AD, leading to cognitive impairment. Therefore, clarifying the pathogenesis of Neuroinflammation and finding effective treatments are the crucial issues for the clinical management of AD.

METHOD

We systematically review the latest research on the pathogenesis and therapeutic strategies of AD in PubMed, Web of Science, and Elsevier SD.

RESULT

In this review, the mechanism of the effect of gut-brain axis lipid metabolism mediated by circadian rhythm on AD was discussed, and we also analysed the effects of inflammation and endoplasmic reticulum stress (ERS) induced by lipid abnormalities on intestinal mucosal barrier and neurodegeneration; furthermore, the importance of lipid homeostasis (phospholipids, fatty acids, sterol) in maintaining the functions of endoplasmic reticulum was emphasized. Meanwhile, as lipid composition affects protein conformation, the membrane phospholipids surrounding sarcoplasmic reticulum Ca2+-ATPase (SERCA) that influence SERCA to release Ca2+ mediating inflammation were also reviewed.

CONCLUSION

We interpreted the mechanism of action between lipid microdomains and ER membrane proteins, reviewed the role of the new pathway of circadian rhythm, lipid metabolism, intestinal mucosa, and brain signaling in the pathogenesis of AD, and proposed strategies to prevent AD by changing the dietary lipid measures.

TRPC6 suppresses liver fibrosis by inhibiting hepatic stellate cell activation via CaMK4-CREB pathway

BACKGROUND AND PURPOSE

Genetic ablation or inhibition of the cation channel TRPC6 is protective against renal, cardiac and intestinal fibrosis. However, TRPC6 expression is decreased in patients with liver diseases. Here, we explored the role of TRPC6 in liver fibrosis and the underlying mechanism.

EXPERIMENTAL APPROACH

Bile duct ligation and thioacetamide gavage were used to model liver fibrosis in C57BL/6J mice. Western blotting, immunolabelling and qPCR were employed for protein and mRNA expression. Liver injury/fibrosis were assessed using serum alanine transaminase and aspartate transaminase assays, haematoxylin-eosin, Masson and Sirius red staining. Adenoviruses were used to overexpress TRPC6 and CREB1Y134F. ChIP and dual-luciferase reporter assays were performed to test the direct inhibition of Acta2 transcription by CREB.

KEY RESULTS

TRPC6 protein levels were decreased in fibrotic liver tissues from both patients and mice, with the decrease being more robust in fibrotic areas. In hepatic stellate cells (HSCs), TRPC6 ablation aggravated liver injury and fibrosis, which was alleviated by overexpressing TRPC6. In primary cultured HSCs, deletion of TRPC6 exacerbated self-activation of HSCs, which was reversed by restoration of TRPC6 expression. Mechanistically, TRPC6 suppressed HSC activation through CaMK4-mediated CREB phosphorylation. CREB directly interacted with the promoter region of Acta2 to inhibit its transcription. Expression of a constitutively active form of CREB1 (CREB1Y134F) in HSCs attenuated BDL-induced liver injury/fibrosis in TRPC6 knockout mice.

CONCLUSION AND IMPLICATIONS

Deficiency of TRPC6 aggravates liver injury/fibrosis through augmentation of HSC activation. Increasing TRPC6 expression/function would be therapeutically beneficial for fibrotic liver diseases.

Impact of Oxidative Stress and Neuroinflammation on Sarco/Endoplasmic Reticulum Ca2+-ATPase 2b Downregulation and Endoplasmic Reticulum Stress in Temporal Lobe Epilepsy

Epilepsy is one of the most common neurological disorders. Calcium dysregulation and neuroinflammation are essential and common mechanisms in epileptogenesis. Sarco/endoplasmic reticulum (ER) Ca2+-ATPase 2b (SERCA2b), a crucial calcium regulatory pump, plays pathological roles in various calcium dysregulation-related diseases. However, the link between SERCA2b and neuroinflammation in epilepsy remains undetermined. This study aimed to establish the relationship between SERCA2b, oxidative stress, and neuroinflammation in epilepsy to elucidate the underlying molecular mechanism in epileptogenesis. Neuroinflammation and oxidative stress were induced in N2a cells using lipopolysaccharide (LPS) and hydrogen peroxide (H2O2). However, experimental temporal lobe epilepsy (TLE) was induced in mice using pilocarpine. Further, effects of oxidative stress and neuroinflammation on SERCA2b and ER stress markers were assessed at protein and mRNA levels. Calcium imaging was employed to determine intracellular calcium levels. SERCA2b expression significantly decreased after LPS, H2O2, and pilocarpine exposure at both mRNA and protein levels, mediated by upregulating neuroinflammation. This downregulation of SERCA2b was associated with increased production of reactive oxygen species and elevated intracellular calcium levels, leading to elevated ER stress markers. Our findings highlight a link between oxidative stress, neuroinflammation and SERCA2b in TLE. The results suggest that targeting SERCA2b could restore calcium homeostasis and ER stress processes, potentially providing a therapeutic option for TLE. This study underscores the importance of SERCA2b in the pathophysiology of epilepsy and its potential as a therapeutic target.

Jun modulates endoplasmic reticulum stress-associated ferroptosis in dorsal root ganglia neurons during neuropathic pain by regulating Timp1

Neuropathic pain (NP) is a complex disorder caused by lesions or diseases affecting the somatosensory nervous system, severely impacting patients' quality of life. Recent studies suggest ferroptosis may be involved in NP induction, but its precise mechanisms remain unclear. We used GO and KEGG pathway enrichment analyses to functionally annotate ferroptosis-related differentially expressed genes (FRDs). Through STRING and the maximum cluster centrality (MCC) algorithm, we identified five hub FRDs (Jun, Timp1, Egfr, Cdkn1a, Cdkn2a). Single-cell analysis revealed significant expression of Jun and Timp1 in neurons. Our study confirmed the association between ferroptosis and endoplasmic reticulum stress (ERS) in NP and validated changes in hub FRD expression across various NP animal models. In vitro experiments demonstrated that Jun regulates neuronal ferroptosis and ERS, particularly by modulating Timp1 expression. Transcription factor prediction and JASPAR binding site analysis elucidated the regulatory network involving Jun. ROC curve analysis of external datasets highlighted the diagnostic potential of hub FRDs and ERS-related differentially expressed genes (ERSRDs) in NP. Using the Comparative Toxicogenomics Database (CTD), we identified estradiol (E2) as a potential therapeutic drug targeting hub FRDs and ERSRDs. Molecular docking predicted its binding sites with Jun and Timp1, and in vivo experiments confirmed that E2 alleviated NP and reversed the expression of Jun and Timp1. This study underscores the crucial role of Jun and Timp1 in the interplay between ferroptosis and ERS, offering new insights and promising avenues for NP treatment.

Endoplasmic reticulum stress: The underlying mechanism of chronic pain

Chronic pain (CP) affects over 30 % of the global population, imposing significant financial burdens on individuals and society. However, existing treatments for CP offer limited efficacy and troublesome side effects, primarily owing to a lack of knowledge of its precise underlying mechanism. Pathological stimuli disrupt the intricate process of protein folding and endoplasmic reticulum (ER) homeostasis. This disruption leads to the accumulation of misfolded or unfolded proteins in the ER, generating a condition termed ER stress. Emerging data have indicated that ER stress, occurring in the peripheral and central nervous systems, contributes to the development and maintenance of CP. This review aimed to comprehensively explore the intersection of ER stress and CP within the lower and upper nervous systems and highlight the cell-specific contributions of the unfolded protein response in different CP types. We provide a comprehensive synthesis of evidence from animal models, examining neuronal and non-neuronal mechanisms and discuss the damaging ER stress-linked inflammation, autophagy, oxidative stress, and apoptosis, which collectively drive disease progression and contribute to a neurotoxic environment. However, the mechanisms through which ER stress influences the most advanced centre-of-pain projections in the brain remain unclear. Further investigation in this area is crucial to elucidate the relationship between ER stress and CP and facilitate the development of novel therapeutic drugs for this intractable dilemma.

Fu's subcutaneous needling promotes axonal regeneration and remyelination by inhibiting inflammation and endoplasmic reticulum stress

Fu's subcutaneous needling (FSN) is a traditional Chinese acupuncture procedure used to treat pain-related neurological disorders. Moreover, the regulation of inflammatory cytokines may provide a favorable environment for peripheral nerve regeneration. In light of this, FSN may be an important novel therapeutic strategy to alleviate pain associated with peripheral neuropathy; however, the underlying molecular mechanisms remain unclear. This study revealed that patients who had osteoarthritis with peripheral neuropathic pain significantly recovered after 1 to 2 weeks of FSN treatment according to the visual analog scale, Western Ontario and McMaster Universities Osteoarthritis Index, Lequesne index, walking speed, and passive range of motion. Similarly, we demonstrated that FSN treatment in an animal model of chronic constriction injury (CCI) significantly improved sciatic nerve pain using paw withdrawal thresholds, sciatic functional index scores, and compound muscle action potential amplitude tests. In addition, transmission electron microscopy images of sciatic nerve tissue showed that FSN effectively reduced axonal swelling, abnormal myelin sheaths, and the number of organelle vacuoles in CCI-induced animals. Mechanistically, RNA sequencing and gene set enrichment analysis revealed significantly reduced inflammatory pathways, neurotransmitters, and endoplasmic reticulum stress pathways and increased nerve regeneration factors in the FSN+CCI group, compared with that in the CCI group. Finally, immunohistochemistry, immunoblotting and enzyme-linked immunosorbent assay showed similar results in the dorsal root ganglia and sciatic nerve. Our findings suggest that FSN can effectively ameliorate peripheral neuropathic pain by regulate inflammation and endoplasmic reticulum stress, thereby determine its beneficial application in patients with peripheral nerve injuries.

Scutellarein ameliorates dextran sulfate sodium-induced ulcerative colitis by inhibiting colonic epithelial cell proinflammation and barrier disruption

Introduction

Scutellarein (Scu) is a natural occurring flavonoid found in multiple traditional Chinese medicines such as Oroxylum indicum (L.) Kurz and Scutellaria baicalensis, with various pharmacological activities including anti-inflammation, anti-oxidation and myocardial protection. Here, we investigated the therapeutic efficacy of Scu on ulcerative colitis (UC) and the underlying mechanism.

Methods

Efficacy of Scu on UC was evaluated in dextran sulfate sodium (DSS) induced colitis mouse model. Inflammation in colonic tissues was assessed by myeloperoxidase activity assay and RT-qPCR. Barrier proteins expression was examined using immunostaining and Western blot. IL-1β-treated HT-29 cells was used for mechanical investigation.

Results

Gavage of Scu significantly decreased the DAI score, improved colon shortening, ameliorated the pathological score in DSS-treated mice with better efficacy than the positive drug, 5-aminosalicylic acid. Scu also inhibited the expression levels of cytokines (Il-1β, Tnf-α, Il-1α, Il-6, and Cxcl1) as well as barrier proteins (E-cadherin, Occludin, and ZO-1) in colon tissues of DSS mice. In intestinal epithelial HT-29 cells, Scu attenuated the IL-1β-downregulated expression levels of E-cadherin, occludin, and ZO-1, while reduced IL-1β-upregulated IL-6 and IL-8 mRNA levels. Moreover, Scu inhibited the phosphorylation and nuclear translocation of NF-κB and suppression of NF-κB phosphorylation abolished IL-1β-disrupted epithelial barrier integrity and IL-1β-upregulated proinflammatory mediators expression in HT-29 cells.

Conclusion

These data demonstrate that Scu is an efficacious therapeutic agent to treat UC. Inhibition of inflammatory responses and maintenance of epithelial barrier integrity through NF-κB signaling pathway underlines Scu therapeutic effect on UC.

Mitigation of ROS-triggered endoplasmic reticulum stress by upregulating Nrf2 retards diabetic nephropathy

Endoplasmic reticulum stress (ERS) plays a crucial role in the pathogenesis of diabetic nephropathy (DN), and it is often accompanied by an increase in reactive oxygen species (ROS) production. However, the precise relationship between NFE2-related factor-2 (Nrf2), a key regulator of ROS balance, and ERS in DN remains elusive. This study aimed to investigate the impact of Nrf2 on ERS and its therapeutic potential in DN. Herein, ERS-related changes, including increased activating transcription factor-6 (ATF6), glucose-regulated protein 78 (GRP78), and transcription factor C/EBP homologous protein (CHOP) expression, were observed in the renal tissues of streptozotocin-induced DN mice and high glucose cultured human renal proximal tubular (HK-2) cells. Nrf2 knockdown increased the sensitivity of HK-2 cells to ERS under high glucose conditions, underscoring the regulatory role of Nrf2 in ERS modulation. Notably, upregulating Nrf2 in ezetimibe-treated diabetic mice restored ERS markers and ameliorated albuminuria, glomerular hypertrophy, mesangial expansion, and tubulointerstitial fibrosis. Furthermore, the inhibition of ERS in HK-2 cells by the ROS scavenger, N-acetylcysteine, highlights the interplay between ROS and ERS. This study, for the first time, elucidates that the upregulation of Nrf2 may alleviate the negative influence of ROS-mediated ERS, presenting a promising therapeutic avenue for delaying the progression of DN. These findings suggest a potential strategy for targeting Nrf2 and ERS in developing novel therapeutic interventions for DN.

Unraveling the Connection: Pain and Endoplasmic Reticulum Stress

Pain is a complex and multifaceted experience. Recent research has increasingly focused on the role of endoplasmic reticulum (ER) stress in the induction and modulation of pain. The ER is an essential organelle for cells and plays a key role in protein folding and calcium dynamics. Various pathological conditions, such as ischemia, hypoxia, toxic substances, and increased protein production, may disturb protein folding, causing an increase in misfolding proteins in the ER. Such an overload of the folding process leads to ER stress and causes the unfolded protein response (UPR), which increases folding capacity in the ER. Uncompensated ER stress impairs intracellular signaling and cell function, resulting in various diseases, such as diabetes and degenerative neurological diseases. ER stress may be a critical universal mechanism underlying human diseases. Pain sensations involve the central as well as peripheral nervous systems. Several preclinical studies indicate that ER stress in the nervous system is enhanced in various painful states, especially in neuropathic pain conditions. The purpose of this narrative review is to uncover the intricate relationship between ER stress and pain, exploring molecular pathways, implications for various pain conditions, and potential therapeutic strategies.

Endoplasmic reticular stress as an emerging therapeutic target for chronic pain: a narrative review

Chronic pain is a severely debilitating condition with enormous socioeconomic costs. Current treatment regimens with nonsteroidal anti-inflammatory drugs (NSAIDs), steroids, or opioids have been largely unsatisfactory with uncertain benefits or severe long-term side effects. This is mainly because chronic pain has a multifactorial aetiology. Although conventional pain medications can alleviate pain by keeping several dysfunctional pathways under control, they can mask other underlying pathological causes, ultimately worsening nerve pathologies and pain outcome. Recent preclinical studies have shown that endoplasmic reticulum (ER) stress could be a central hub for triggering multiple molecular cascades involved in the development of chronic pain. Several ER stress inhibitors and unfolded protein response modulators, which have been tested in randomised clinical trials or apprpoved by the US Food and Drug Administration for other chronic diseases, significantly alleviated hyperalgesia in multiple preclinical pain models. Although the role of ER stress in neurodegenerative disorders, metabolic disorders, and cancer has been well established, research on ER stress and chronic pain is still in its infancy. Here, we critically analyse preclinical studies and explore how ER stress can mechanistically act as a central node to drive development and progression of chronic pain. We also discuss therapeutic prospects, benefits, and pitfalls of using ER stress inhibitors and unfolded protein response modulators for managing intractable chronic pain. In the future, targeting ER stress to impact multiple molecular networks might be an attractive therapeutic strategy against chronic pain refractory to steroids, NSAIDs, or opioids. This novel therapeutic strategy could provide solutions for the opioid crisis and public health challenge.

Arbidol attenuates liver fibrosis and activation of hepatic stellate cells by blocking TGF-β1 signaling

Chronic liver diseases (CLD) impact over 800 million people globally, causing about 2 million deaths annually. Arbidol (ARB), an indole-derivative used to treat influenza virus infection, was extensively used during COVID-19 pandemic in China. In recent years, studies have shown that ARB, compared to other antiviral drugs, exhibits greater liver-protective efficacy, indicating a potential hepatoprotective effect beyond its antiviral activity. However, the mechanism remains unclear. In this study, we investigated the impact of ARB on liver injury/fibrosis in bile duct ligated (BDL) mice and its effect on spontaneous and transforming growth factor β1 (TGF-β1)-induced activation of primary cultured hepatic stellate cells (HSCs). Oral administration of ARB significantly ameliorated BDL-induced liver injury/fibrosis as reflected by decreased serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), reduced collagen deposition, and diminished mRNA expression of fibrosis markers. ARB notably inhibited spontaneous and TGF-β1-induced activation of primary cultured HSCs. Moreover, ARB also drastically attenuated mRNA expression levels of platelet-derived growth factor receptor (Pdgfr), transforming growth factor-beta receptor (Tgfbr) 1, Tgfbr2, matrix metalloproteinase (Mmp)-2, and Mmp-9 in activated HSCs. We further demonstrate that ARB mitigated Smad2/3 phosphorylation in both TGF-β1 treated HSCs and BDL mice. These data together demonstrate that the therapeutic efficacy of ARB on liver fibrosis is independent of its antiviral activity and likely is achieved by blocking TGF-β1 signaling-mediated HSC activation.

Influence of bifenthrin exposure at different gestational stages on the neural development

Perinatal exposure to bifenthrin (BF) alters neurodevelopment. However, the most susceptible time period to BF exposure and the possible mechanisms are not clear. In the current study, pregnant female mice were treated with BF (0.5 mg/kg/d) at three different stages [gestational day (GD) 0-5, 6-15 and 16-birth (B)] and neurologic deficits were evaluated in offspring mice. BF exposure at GD 16-B significantly altered the locomotor activity and caused learning and memory impairments in 6-week-old offspring. Gestational BF exposure also caused neuronal loss in the region of cornu ammonis of hippocampi of 6-week-old offspring. Interestingly, neurobehavioral impairments and neuronal loss were not observed in offspring at 10-week-old. BF exposure at GD 16-B also decreased protein levels of VGluT1, NR1 and NR2A while increased the protein levels of NR2B and VGAT1, as well as the gene levels of Il-1β, Il-6 and Tnf-α in hippocampi of 6-week-old offspring. Collectively, these data demonstrate that gestational exposure to a low dose BF causes neurodevelopmental deficits that remit with the age and the late-stage of pregnancy is the most susceptible time window to BF exposure. Imbalance in excitatory/inhibitory neuronal transmission, altered expression levels of NMDA receptors and increased neural inflammation may be associated with BF prenatal exposure-triggered neurobehavioral impairments.

CDN1163, a SERCA activator, causes intracellular Ca2+ leak, mitochondrial hyperpolarization and cell cycle arrest in mouse neuronal N2A cells

OBJECTIVE

Activity or expression of sarcoplasmic/endoplasmic reticulum Ca2+ ATPase (SERCA) is diminished in some disease states such as cardiac failure and diabetes mellitus. A newly developed activator of SERCA, CDN1163, reportedly rescued or alleviated pathological conditions attributed to dysfunctional SERCA. We examined whether CDN1163 could relieve mouse neuronal N2A cell growth inhibition caused by cyclopiazonic acid (CPA, SERCA inhibitor). We also examined how CDN1163 affected cytosolic Ca2+, mitochondrial Ca2+ and mitochondrial membrane potential.

METHODS

Cell viability was measured by MTT assay and trypan blue exclusion test. Cytosolic Ca2+, mitochondrial Ca2+ and mitochondrial membrane potential were measured using fura 2, Rhod-2 and JC-1, respectively, as fluorescent probes.

RESULTS

CDN1163 (10 μM) itself suppressed cell proliferation, and did not alleviate CPA's inhibitory effect (and vice versa). Cell cycle was arrested at the G1 phase after CDN1163 treatment. CDN1163 treatment caused a slow yet persistent cytosolic [Ca2+] elevation partly due to Ca2+ release from an internal store other than the CPA-sensitive endoplasmic reticulum (ER). Treatment with CDN1163 for 3 h raised mitochondrial Ca2+ level and such increase was suppressed by MCU-i4 (an inhibitor of mitochondria Ca2+ uniporter, MCU), suggesting Ca2+ entered the mitochondrial matrix through MCU. Treatment of cells with CDN1163 up to 2 days resulted in mitochondrial hyperpolarization.

CONCLUSION

CDN1163 caused internal Ca2+ leak, cytosolic Ca2+ overload, mitochondrial Ca2+ elevation and hyperpolarization, cell cycle arrest and cell growth inhibition.

SARS-CoV-2 airway infection results in the development of somatosensory abnormalities in a hamster model

Although largely confined to the airways, SARS-CoV-2 infection has been associated with sensory abnormalities that manifest in both acute and chronic phenotypes. To gain insight on the molecular basis of these sensory abnormalities, we used the golden hamster model to characterize and compare the effects of infection with SARS-CoV-2 and influenza A virus (IAV) on the sensory nervous system. We detected SARS-CoV-2 transcripts but no infectious material in the cervical and thoracic spinal cord and dorsal root ganglia (DRGs) within the first 24 hours of intranasal virus infection. SARS-CoV-2-infected hamsters exhibited mechanical hypersensitivity that was milder but prolonged compared with that observed in IAV-infected hamsters. RNA sequencing analysis of thoracic DRGs 1 to 4 days after infection suggested perturbations in predominantly neuronal signaling in SARS-CoV-2-infected animals as opposed to type I interferon signaling in IAV-infected animals. Later, 31 days after infection, a neuropathic transcriptome emerged in thoracic DRGs from SARS-CoV-2-infected animals, which coincided with SARS-CoV-2-specific mechanical hypersensitivity. These data revealed potential targets for pain management, including the RNA binding protein ILF3, which was validated in murine pain models. This work elucidates transcriptomic signatures in the DRGs triggered by SARS-CoV-2 that may underlie both short- and long-term sensory abnormalities.

Calcium regulation by SERC-A before and during Alzheimer disease

There are many factors involved in the incidence of Alzheimer’s disease that, in combination, impede or hinder normal neuronal functions. Little is currently known about calcium regulation before and during the disease. Internal instability of calcium levels is associated with increased vascular risk, a prevalent condition in a high number of individuals already compromised by Alzheimer’s disease. This review provides a reevaluation of the molecular mechanism of the sarcoendoplasmic reticulum calcium ATPase (SERC-A) in the disease and discusses salient aspects of voltage-gated calcium channel function; in these way new alternatives could be open for its treatment. These regulation mechanisms are clinically relevant since the irregular functions of SERC+A has been implicated in pathologies of brain function.

SARS-CoV-2 Airway Infection Results in Time-dependent Sensory Abnormalities in a Hamster Model

Despite being largely confined to the airways, SARS-CoV-2 infection has been associated with sensory abnormalities that manifest in both acute and long-lasting phenotypes. To gain insight on the molecular basis of these sensory abnormalities, we used the golden hamster infection model to characterize the effects of SARS-CoV-2 versus Influenza A virus (IAV) infection on the sensory nervous system. Efforts to detect the presence of virus in the cervical/thoracic spinal cord and dorsal root ganglia (DRGs) demonstrated detectable levels of SARS-CoV-2 by quantitative PCR and RNAscope uniquely within the first 24 hours of infection. SARS-CoV-2-infected hamsters demonstrated mechanical hypersensitivity during acute infection; intriguingly, this hypersensitivity was milder, but prolonged when compared to IAV-infected hamsters. RNA sequencing (RNA-seq) of thoracic DRGs from acute infection revealed predominantly neuron-biased signaling perturbations in SARS-CoV-2-infected animals as opposed to type I interferon signaling in tissue derived from IAV-infected animals. RNA-seq of 31dpi thoracic DRGs from SARS-CoV-2-infected animals highlighted a uniquely neuropathic transcriptomic landscape, which was consistent with substantial SARS-CoV-2-specific mechanical hypersensitivity at 28dpi. Ontology analysis of 1, 4, and 30dpi RNA-seq revealed novel targets for pain management, such as ILF3. Meta-analysis of all SARS-CoV-2 RNA-seq timepoints against preclinical pain model datasets highlighted both conserved and unique pro-nociceptive gene expression changes following infection. Overall, this work elucidates novel transcriptomic signatures triggered by SARS-CoV-2 that may underlie both short- and long-term sensory abnormalities while also highlighting several therapeutic targets for alleviation of infection-induced hypersensitivity.

One Sentence Summary

SARS-CoV-2 infection results in an interferon-associated transcriptional response in sensory tissues underlying time-dependent hypersensitivity.

Corydecumine G inhibits microglia activation via MAPK pathway in a rat model of neuropathic pain

BACKGROUND AND PURPOSE

Microglial activation plays an important role in the onset and progression of neuropathic pain by producing a variety of pro-inflammatory cytokines that interact with neurons to enhance neuronal hyperexcitability. Corydalis decumbens (Thunb.) pers., a traditional Chinese medicine has been used to treat mild cancer pain, dementia and to remit cerebral ischemia in clinics. Phenylphthalide isoquinolines are the major type of metabolites of C. decumbens and one of the derivatives, Corydecumine G (Cor G) has been shown to inhibit neuronal excitability. The present study aims to investigate the analgesic efficacy of Cor G in neuropathic pain rat model, the effects of Cor G on microglia activation and the possible mechanisms.

EXPERIMENTAL APPROACH

Neuropathic pain was modeled using chronic constriction sciatic nerve injury (CCI) in rats. Western blot, immunofluorescence, and qRT-PCR were used to evaluate the levels of protein and mRNA.

KEY RESULTS

Intraperitoneal administration of Cor G concentration-dependently ameliorates mechanical and thermo allodynia, suppresses CCI-induced p38/ERK phosphorylation and spinal cord microglia activation, and attenuates the expression levels of NO, inos, Tnf-α, Pge₂ in dorsal horn of L4-L6 spinal cord on the ligation side in CCI rats. Pretreatment with 30 μM Cor G decreased LPS-induced BV2 microglia activation, which occurred via the inos, Tnf-α, Il-1β, Il-6 and phospho-p38/ERK pathways.

CONCLUSIONS AND IMPLICATIONS

Taken together, we suggest that Cor G, the specific phthalide isoquinoline from traditional Chinese medicine Corydalis Decumbentis Rhizoma, may be promising for treatment of neuropathic pain.

Restoration of Sarco/Endoplasmic Reticulum Ca2+-ATPase Activity Functions as a Pivotal Therapeutic Target of Anti-Glutamate-Induced Excitotoxicity to Attenuate Endoplasmic Reticulum Ca2+ Depletion

Glutamate-induced excitotoxicity is a pathological basis of many acute/chronic neurodegenerative diseases. Sarco/endoplasmic reticulum Ca2+-ATPase (SERCA2b) is a membrane-embedded P-type ATPase pump that manages the translocation of calcium ions (Ca2+) from cytosol into the lumen of the endoplasmic reticulum (ER) calcium stores. It participates in a wide range of biological functions in the central nervous system (CNS). However, the role of SERCA2b in glutamate-induced excitotoxicity and its mechanism must be elucidated. Herein, we demonstrate that SERCA2b mutants exacerbate the excitotoxicity of hypo-glutamate stimulation on HT22 cells. In this study, SERCA2b mutants accelerated Ca2+ depletion through loss-of-function (reduced pumping capacity) or gain-of-function (acquired leakage), resulting in ER stress. In addition, the occurrence of ER Ca2+ depletion increased mitochondria-associated membrane formation, which led to mitochondrial Ca2+ overload and dysfunction. Moreover, the enhancement of SERCA2b pumping capacity or inhibition of Ca2+ leakage attenuated Ca2+ depletion and impeded excitotoxicity in response to hypo-glutamate stimulation. In conclusion, SERCA2b mutants exacerbate ER Ca2+-depletion-mediated excitotoxicity in glutamate-sensitive HT22 cells. The mechanism of disruption is mainly related to the heterogeneity of SERCA2b mutation sites. Stabilization of SRECA2b function is a critical therapeutic approach against glutamate-induced excitotoxicity. These data will expand understanding of organelle regulatory networks and facilitate the discovery and creation of drugs against excitatory/inhibitory imbalance in the CNS.