Extracellular α-crystallin protects astrocytes from cell death through activation of MAPK, PI3K/Akt signaling pathway and blockade of ROS release from mitochondria

Lanosterol regulates abnormal amyloid accumulation in LECs through the mediation of cholesterol pathway metabolism

Age-related cataract (ARC) is the predominant cause of global blindness, linked to the progressive aging of the lens, oxidative stress, perturbed calcium homeostasis, hydration irregularities, and modifications in crystallin proteins. Currently, surgical intervention remains the sole efficacious remedy, albeit carrying inherent risks of complications that may culminate in irreversible blindness. It is urgent to explore alternative, cost-effective, and uncomplicated treatment modalities for cataracts. Lanosterol has been widely reported to reverse cataracts, but the mechanism of action is not yet clear. In this study, we elucidated the mechanism through which lanosterol operates in the context of cataract reversal. Through the targeted suppression of sterol regulatory element-binding protein 2 (SREBP2) followed by lanosterol treatment, we observed the restoration of lipid metabolism disorders induced by SREBP2 knockdown in lens epithelial cells (LECs). Notably, lanosterol exhibited the ability to effectively counteract amyloid accumulation and cellular apoptosis triggered by lipid metabolism disorders. In summary, our findings suggest that lanosterol, a pivotal intermediate in lipid metabolism, may exert its therapeutic effects on cataracts by influencing lipid metabolism. This study shed light on the treatment and pharmaceutical development targeting Age-related Cataracts (ARC).

The role of PI3k/AKT signaling pathway in attenuating liver fibrosis: a comprehensive review

Excessive accumulation of extracellular matrix (ECM) components within the liver leads to a pathological condition known as liver fibrosis. Alcohol abuse, non-alcoholic fatty liver disease (NAFLD), autoimmune issues, and viral hepatitis cause chronic liver injury. Exploring potential therapeutic targets and understanding the molecular mechanisms involved in liver fibrosis are essential for the development of effective interventions. The goal of this comprehensive review is to explain how the PI3K/AKT signaling pathway contributes to the reduction of liver fibrosis. The potential of this pathway as a therapeutic target is investigated through a summary of results from in vivo and in vitro studies. Studies focusing on PI3K/AKT activation have shown a significant decrease in fibrosis markers and a significant improvement in liver function. The review emphasizes how this pathway may prevent ECM synthesis and hepatic stellate cell (HSC) activation, ultimately reducing the fibrotic response. The specific mechanisms and downstream effectors of the PI3K/AKT pathway in liver fibrosis constitute a rapidly developing field of study. In conclusion, the PI3K/AKT signaling pathway plays a significant role in attenuating liver fibrosis. Its complex role in regulating HSC activation and ECM production, demonstrated both in vitro and in vivo, underscores its potential as a effective therapeutic approach for managing liver fibrosis and slowing disease progression. A comprehensive review of this field provides valuable insights into its future developments and implications for clinical applications.

Functional Diversity of Mammalian Small Heat Shock Proteins: A Review

The small heat shock proteins (sHSPs), whose molecular weight ranges from 12∼43 kDa, are members of the heat shock protein (HSP) family that are widely found in all organisms. As intracellular stress resistance molecules, sHSPs play an important role in maintaining the homeostasis of the intracellular environment under various stressful conditions. A total of 10 sHSPs have been identified in mammals, sharing conserved α-crystal domains combined with variable N-terminal and C-terminal regions. Unlike large-molecular-weight HSP, sHSPs prevent substrate protein aggregation through an ATP-independent mechanism. In addition to chaperone activity, sHSPs were also shown to suppress apoptosis, ferroptosis, and senescence, promote autophagy, regulate cytoskeletal dynamics, maintain membrane stability, control the direction of cellular differentiation, modulate angiogenesis, and spermatogenesis, as well as attenuate the inflammatory response and reduce oxidative damage. Phosphorylation is the most significant post-translational modification of sHSPs and is usually an indicator of their activation. Furthermore, abnormalities in sHSPs often lead to aggregation of substrate proteins and dysfunction of client proteins, resulting in disease. This paper reviews the various biological functions of sHSPs in mammals, emphasizing the roles of different sHSPs in specific cellular activities. In addition, we discuss the effect of phosphorylation on the function of sHSPs and the association between sHSPs and disease.

Deletion of Cryab increases the vulnerability of mice to the addiction-like effects of the cannabinoid JWH-018 via upregulation of striatal NF-κB expression

Synthetic cannabinoids have exhibited unpredictable abuse liabilities, especially self-administration (SA) responses in normal rodent models, despite seemingly inducing addiction-like effects in humans. Thus, an efficient pre-clinical model must be developed to determine cannabinoid abuse potential in animals and describe the mechanism that may mediate cannabinoid sensitivity. The Cryab knockout (KO) mice were recently discovered to be potentially sensitive to the addictive effects of psychoactive drugs. Herein, we examined the responses of Cryab KO mice to JWH-018 using SA, conditioned place preference, and electroencephalography. Additionally, the effects of repeated JWH-018 exposure on endocannabinoid- and dopamine-related genes in various addiction-associated brain regions were examined, along with protein expressions involving neuroinflammation and synaptic plasticity. Cryab KO mice exhibited greater cannabinoid-induced SA responses and place preference, along with divergent gamma wave alterations, compared to wild-type (WT) mice, implying their higher sensitivity to cannabinoids. Endocannabinoid- or dopamine-related mRNA expressions and accumbal dopamine concentrations after repeated JWH-018 exposure were not significantly different between the WT and Cryab KO mice. Further analyses revealed that repeated JWH-018 administration led to possibly greater neuroinflammation in Cryab KO mice, which may arise from upregulated NF-κB, accompanied by higher expressions of synaptic plasticity markers, which might have contributed to the development of cannabinoid addiction-related behavior in Cryab KO mice. These findings signify that increased neuroinflammation via NF-κB may mediate the enhanced addiction-like responses of Cryab KO mice to cannabinoids. Altogether, Cryab KO mice may be a potential model for cannabinoid abuse susceptibility.

αA-Crystallin Mediated Neuroprotection in the Retinal Neurons Is Independent of Protein Kinase B

Phosphatidylinositol 3-kinase (PI3K)/Akt signal pathway mediates pro-survival function in neurons. In the retina, PI3K/AKT/mTOR signaling pathway is related to the early pathogenesis of diabetic retinopathy. Signaling molecules in the membrane-initiated signaling pathway exhibiting neuroprotective function interacts with the PI3K/Akt pathway as an important survival pathway. Molecular chaperone α-crystallins are known to potentially interact and/or regulate various pro-survival and pro-apoptotic proteins to regulate cell survival. Among these demonstrated mechanisms, they are well-reported to regulate and inhibit apoptosis by interacting and sequestrating the proapoptotic proteins such as Bax and Bcl-Xs. We studied the importance of metabolic stress-induced enhanced Akt signaling and αA-crystallin interdependence for exhibiting neuroprotection in metabolically challenged retinal neurons. For the first time, this study has revealed that αA-crystallin and activated Akt are significantly neuroprotective in the stressed retinal neurons, independent of each other. Furthermore, the study also highlighted that significant inhibition of the PI3K-Akt pathway does not alter the neuroprotective ability of αA-crystallin in stressed retinal neurons. Interestingly, our study also demonstrated that in the absence of Akt activation, αA-crystallin inhibits the translocation of Bax in the mitochondria during metabolic stress, and this function is regulated by the phosphorylation of αA-crystallin on residue 148.

Crystallin Alpha-B Overexpression as a Possible Marker of Reactive Astrogliosis in Human Cerebral Contusions

The pathophysiology of traumatic brain injury (TBI) has not yet been fully elucidated. Crystallin alpha-B (CRYAB) is a molecular chaperone that apparently tries to stabilize the rapid thickening of the intermediate filaments of glial fibrillary acidic protein (GFAP) during the process of reactive astrogliosis in response to TBI. Previous analyses of the gene expression profile in human brain contusion tissue showed us an exacerbated CRYAB overexpression. Here, we used 3, 3’-diaminobenzidine (DAB) immunohistochemistry and immunofluorescence to verify CRYAB overexpression and to describe its expression and distribution in samples of contused cortical tissue derived from emergency decompressive surgery after severe TBI. The histological expression of CRYAB was mainly seen in subcortical white matter astrocytes of injured tissue. Most of the cells that overexpressed GFAP in the analyzed tissue also overexpressed CRYAB, a finding corroborated by the co-localization of the two markers. The only difference was the presence of a few pyramidal neurons that expressed CRYAB in layer V of the cerebral cortex. The selective vulnerability of layer V of the cerebral cortex during TBI could explain the expression of CRYAB in neurons of this cortical layer. Our results indicate a parallel behavior in the cellular expression of CRYAB and GFAP during the subacute response to TBI. These results lead us to postulate CRYAB as a possible marker of reactive astrogliosis in contused cortical tissue.

Extracellular vesicle-associated small heat shock proteins as therapeutic agents in neurodegenerative diseases and beyond

Increasing evidence points towards using extracellular vesicles (EVs) as a therapeutic strategy in neurodegenerative diseases such as multiple sclerosis, Parkinson's, and Alzheimer's disease. EVs are nanosized carriers that play an essential role in intercellular communication and cellular homeostasis by transporting an active molecular cargo, including a large variety of proteins. Recent publications demonstrate that small heat shock proteins (HSPBs) exhibit a beneficial role in neurodegenerative diseases. Moreover, it is defined that HSPBs target the autophagy and the apoptosis pathway, playing a prominent role in chaperone activity and cell survival. This review elaborates on the therapeutic potential of EVs and HSPBs, in particular HSPB1 and HSPB8, in neurodegenerative diseases. We conclude that EVs and HSPBs positively influence neuroinflammation, central nervous system (CNS) repair, and protein aggregation in CNS disorders. Moreover, we propose the use of HSPB-loaded EVs as advanced nanocarriers for the future development of neurodegenerative disease therapies.

Dual Roles of Nicotinamide Phosphoribosyltransferase as a Promising Target for Cancer Radiotherapy

Nicotinamide phosphoribosyltransferase (NAMPT) is the key rate-limiting enzyme in the regulation of nicotinamide adenine dinucleotide (NAD) biosynthesis, and its activity is critical for the replenishment of NAD level as well as cell survival or death. As one of the most important components in the electron transport chain of complex I in mitochondrion, sustained supply of NAD is essential to the maintenance of energy metabolism both in normal and cancer cells. Recent research showed that X-ray radiation sharply downregulated the expression of NAMPT, which may be the main cause of radiation damage in salivary gland. Consistently, upregulation of NAMPT by phenylephrine restored the function and tissue structure of salivary gland, indicating the cytoprotective role of NAMPT in preventing radiation damage in normal tissues of patients with head and neck cancer during radiotherapy. On the other hand, NAMPT downregulation and NAD depletion could induce cell death in oral squamous cell cancer, suggesting that a combination of NAMPT inhibitor and radiotherapy presents a promising therapeutic strategy for cancer treatment. Based on our and other's studies, NAMPT may have dual roles in cancer radiotherapy: the upregulation of NAMPT could serve to suppress radiotherapy complications such as radiation sialadenitis, and combination regimens that involve NAMPT inhibitors may enhance efficacy of radiotherapy for cancer treatment.

The engineered expression of secreted HSPB5-Fc in CHO cells exhibits cytoprotection in vitro

Background

HSPB5 is an ATP-independent molecular chaperone that is induced by heat shock or other proteotoxic stresses. HSPB5 is cytoprotective against stress both intracellularly and extracellularly. It acts as a potential therapeutic candidate in ischemia-reperfusion and neurodegenerative diseases.

Results

In this paper, we constructed a recombinant plasmid that expresses and extracellularly secrets a HSPB5-Fc fusion protein (sHSPB5-Fc) at 0.42 μg/ml in CHO-K1 cells. This sHSPB5-Fc protein contains a Fc-tag at the C-terminal extension of HSPB5, facilitating protein-affinity purification. Our study shows that sHSPB5-Fc inhibits heat-induced aggregation of citrate synthase in a time and dose dependent manner in vitro. Administration of sHSPB5-Fc protects lens epithelial cells against cisplatin- or UVB-induced cell apoptosis. It also decreases GFP-Htt^ex1-Q74 insolubility, and reduces the size and cytotoxicity of GFP-Htt^ex1-Q74 aggregates in PC-12 cells.

Conclusion

This recombinant sHSPB5-Fc exhibits chaperone activity to protect cells against proteotoxicity.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12896-021-00700-y.

The Potentials of Melatonin in the Prevention and Treatment of Bacterial Meningitis Disease

Bacterial meningitis (BM) is an acute infectious central nervous system (CNS) disease worldwide, occurring with 50% of the survivors left with a long-term serious sequela. Acute bacterial meningitis is more prevalent in resource-poor than resource-rich areas. The pathogenesis of BM involves complex mechanisms that are related to bacterial survival and multiplication in the bloodstream, increased permeability of blood-brain barrier (BBB), oxidative stress, and excessive inflammatory response in CNS. Considering drug-resistant bacteria increases the difficulty of meningitis treatment and the vaccine also has been limited to several serotypes, and the morbidity rate of BM still is very high. With recent development in neurology, there is promising progress for drug supplements of effectively preventing and treating BM. Several in vivo and in vitro studies have elaborated on understanding the significant mechanism of melatonin on BM. Melatonin is mainly secreted in the pineal gland and can cross the BBB. Melatonin and its metabolite have been reported as effective antioxidants and anti-inflammation, which are potentially useful as prevention and treatment therapy of BM. In bacterial meningitis, melatonin can play multiple protection effects in BM through various mechanisms, including immune response, antibacterial ability, the protection of BBB integrity, free radical scavenging, anti-inflammation, signaling pathways, and gut microbiome. This manuscript summarizes the major neuroprotective mechanisms of melatonin and explores the potential prevention and treatment approaches aimed at reducing morbidity and alleviating nerve injury of BM.

Antibodies from Multiple Sclerosis Brain Identified Epstein-Barr Virus Nuclear Antigen 1 & 2 Epitopes which Are Recognized by Oligoclonal Bands

Multiple sclerosis (MS) is a chronic inflammatory demyelinating disease of the central nervous system (CNS), the etiology of which is poorly understood. The most common laboratory abnormality associated with MS is increased intrathecal immunoglobulin G (IgG) synthesis and the presence of oligoclonal bands (OCBs) in the brain and cerebrospinal fluid (CSF). However, the major antigenic targets of these antibody responses are unknown. The risk of MS is increased after infectious mononucleosis (IM) due to EBV infection, and MS patients have higher serum titers of anti-EBV antibodies than control populations. Our goal was to identify disease-relevant epitopes of IgG antibodies in MS; to do so, we screened phage-displayed random peptide libraries (12-mer) with total IgG antibodies purified from the brain of a patient with acute MS. We identified and characterized the phage peptides for binding specificity to intrathecal IgG from patients with MS and from controls by ELISA, phage-mediated Immuno-PCR, and isoelectric focusing. We identified two phage peptides that share sequence homologies with EBV nuclear antigens 1 and 2 (EBNA1 and EBNA2), respectively. The specificity of the EBV epitopes found by panning with MS brain IgG was confirmed by ELISA and competitive inhibition assays. Using a highly sensitive phage-mediated immuno-PCR assay, we determined specific bindings of the two EBV epitopes to IgG from CSF from 46 MS and 5 inflammatory control (IC) patients. MS CSF IgG have significantly higher bindings to EBNA1 epitope than to EBNA2 epitope, whereas EBNA1 and EBNA2 did not significantly differ in binding to IC CSF IgG. Further, the EBNA1 epitope was recognized by OCBs from multiple MS CSF as shown in blotting assays with samples separated by isoelectric focusing. The EBNA1 epitope is reactive to MS intrathecal antibodies corresponding to oligoclonal bands. This reinforces the potential role of EBV in the etiology of MS.

Graphical abstract

Synergistic protection of RGCs by olfactory ensheathing cells and alpha-crystallin through regulation of the Akt/BAD Pathway

BACKGROUND

Our recent in vivo studies have shown that olfactory ensheathing cells (OECs) and α-crystallin can promote retinal ganglion cell (RGC) survival and axonal regeneration synergistically after optic nerve injury. However, the mechanism is still unknown.

OBJECTIVES

Here, we studied the synergistic effect and mechanism of OECs and α-crystallin on RGC survival after H₂O₂-induced oxidative damage and a crushing injury to the optic nerve in an adult rat model.

METHODS

After H₂O₂-induced oxidative damage, RGC-5 cells were treated with OECs, α-crystallin or a combination of OECs and α-crystallin. Apoptosis of RGC-5 cells was assessed by flow cytometry. Phosphorylated Akt, BAD, and cleaved-caspase3 were detected by Western blot after optic nerve injury in vivo and H₂O₂-induced RGC-5 oxidative damage in vitro.

RESULTS

The results showed that OECs and α-crystallin could both independently inhibit RGC-5 apoptosis (P<0.01), increase the phosphorylation of both Akt and BAD, and decrease the activation of caspase-3 (P<0.01). However, the effect of the combination of both was more significant than either alone.

CONCLUSION

These findings indicate that inhibition of superoxide damage to RGCs through regulation of the Akt/BAD pathway is one of the mechanisms by which OECs and α-crystallin promote optic nerve recovery after injury.

Transcriptomic analysis reveals the role of a peptide derived from CRYAB on the CoCl2-induced hypoxic HL-1 cardiomyocytes

Acute myocardial infarction (AMI) is a life-threatening disease that often results in heart failure. CRYAB, a small heat shock protein, has been shown to have cardioprotective effects against oxidative stress-induced apoptosis in AMI. Previously, we purified a peptide derived from CRYAB (LEDQFFGEH), which we named PDFC. In this study, we determined the function of PDFC on HL-1 cardiomyocytes and explored the mechanism underlying its function. A hypoxic myocardiocyte cell line was generated by stimulation of HL-1 mouse cardiac muscle cells with different concentrations of CoCl₂. Then, the hypoxic HL-1 cells were treated with the synthetic PDFC peptide, and cell proliferation, migration, and apoptosis were assessed to examine the effects of PDFC on HL-1 and hypoxic HL-1 cells. To examine the mechanism underlying the effects of PDFC on hypoxic cells, PDFC-treated hypoxic HL-1 cells were submitted for deep RNA sequencing. Finally, several differentially expressed genes in different pathways were selected for confirmation by RT-qPCR. Hypoxic myocardiocytes were generated by stimulating HL-1 cells with 800 µM CoCl₂ for 24 h, which significantly upregulated HIF-1α. PDFC at 200 µg/ml showed the most positive effects on cell viability. Although hypoxic HL-1 cells and PDFC-treated hypoxic HL-1 cells both showed lower viability and migration and higher levels of apoptosis than untreated HL-1 cells, compared to hypoxic HL-1 cells, PDFC-treated hypoxic HL-1 cells showed higher viability and migration and lower apoptosis. The deep sequencing showed that 812 genes were upregulated and 1946 genes were downregulated. Among these differentially expressed genes, 699 of the upregulated genes and 1488 of the downregulated genes were protein-coding genes. Gene ontology and pathway enrichment analysis showed that the downregulated genes were dominant and that the PI3K-Akt pathway was located in the center of the network. A protein-protein interaction network was constructed, and 892 nodes were determined. In PDFC-treated hypoxic HL-1 cells, Fn1, Pik3r5, and Creb5 were downregulated, while Insr, Bcl2, Mapk14, and Pten were upregulated when compared to the levels in hypoxic HL-1 cells. In conclusion, this study reveals the significant bioactive effect of the CRYAB-derived peptide, PDFC on cardiomyocytes and the underlying mechanism.

Protective Effects of Lanosterol Synthase Up-Regulation in UV-B-Induced Oxidative Stress

UV-B radiation may be an important risk factor in cataract etiology. After exposure to UV-B radiation, cells show imbalances in the repair of DNA damage, which induce changes in the levels of certain proteins, including alpha-crystallin, which is the most abundant protein in the lens and crucial for the maintenance of lens transparency. Lanosterol synthase (LSS), an essential rate-limiting enzyme in cholesterol biosynthesis, might play significant roles in oxidative stress and in the maintenance of lens transparency. However, the roles of LSS in UV-B-induced apoptosis are not well understood. Therefore, we irradiated female Sprague-Dawley rats with ultraviolet radiation to establish an animal model for exploring the variations in LSS expression during the early stages of UV-B exposure. In addition, we cultured human lens epithelial (HLE) cells that overexpress LSS and exposed them to UV-B radiation to explore the function of increased LSS expression in UV-B-induced apoptosis. The data demonstrated that UV-B exposure induced oxidative stress and apoptosis in rat lens epithelial cells and that irradiance exposure increased the level of lenticular damage. Additionally, UV-B exposure decreased the alpha-crystallin content and increased the expressions of Bax and cleaved caspase-3 compared with the control levels. After exposure to UV-B, the apoptosis-related index of HLE cells overexpressing LSS was lower than that of the control cells. Furthermore, ROS overproduction might activate the sirtuin 1 (Sirt1) pathway, which induced protein expressions of sterol regulatory element-binding transcription factor 2 (SREBF2), 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR), and LSS. However, the specific mechanism of the Sirt1 pathway needed to be further studied. In summary, UV-B exposure induced oxidative injury and resulted in crystallin denaturation and apoptosis in lens epithelial cells, and LSS might play a protective role during the early stages of this process and could be an important target in the cataract prevention.

Tumor Homing Reactive Oxygen Species Nanoparticle for Enhanced Cancer Therapy

Multifunctional nanoparticles that carry chemotherapeutic agents can be innovative anticancer therapeutic options owing to their tumor-targeting ability and high drug-loading capacity. However, the nonspecific release of toxic DNA-intercalating anticancer drugs from the nanoparticles has significant side effects on healthy cells surrounding the tumors. Herein, we report a tumor homing reactive oxygen species nanoparticle (THoR-NP) platform that is highly effective and selective for ablating malignant tumors. Sodium nitroprusside (SNP) and diethyldithiocarbamate (DDC) were selected as an exogenous reactive oxygen species (ROS) generator and a superoxide dismutase 1 inhibitor, respectively. DDC-loaded THoR-NP, in combination with SNP treatment, eliminated multiple cancer cell lines effectively by the generation of peroxynitrite in the cells (>95% cell death), as compared to control drug treatments of the same concentration of DDC or SNP alone (0% cell death). Moreover, the magnetic core (ZnFe₂O₄) of the THoR-NP can specifically ablate tumor cells (breast cancer cells) via magnetic hyperthermia, in conjunction with DDC, even in the absence of any exogenous RS supplements. Finally, by incorporating iRGD peptide moieties in the THoR-NP, integrin-enriched cancer cells (malignant tumors, MDA-MB-231) were effectively and selectively killed, as opposed to nonmetastatic tumors (MCF-7), as confirmed in a mouse xenograft model. Hence, our strategy of using nanoparticles embedded with ROS-scavenger-inhibitor with an exogenous ROS supplement is highly selective and effective cancer therapy.

Progression of the role of CRYAB in signaling pathways and cancers

CRYAB is a member of the small heat shock protein family, first discovered in the lens of the eye, and involved in various diseases, such as eye and heart diseases and even cancers, for example, breast cancer, lung cancer, prostate cancer, and ovarian cancer. In addition, CRYAB proteins are involved in a variety of signaling pathways including apoptosis, inflammation, and oxidative stress. This review summarizes the recent progress concerning the role of CRYAB in signaling pathways and diseases. Therefore, the role of CRYAB in signaling pathways and cancers is urgently needed. This article reviews the regulation of CRYAB in the apoptotic inflammatory signaling pathway and its role in cancers progression and as a key role in anti-cancer therapy targeting CRYAB in an effort to improve outcomes for patients with metastatic disease.

Coenzyme Q10 Protects Astrocytes from Ultraviolet B-Induced Damage Through Inhibition of ERK 1/2 Pathway Overexpression

Overexpression of extracellular signal-regulated kinase ½ (ERK ½) signaling pathway leads to overproduction of reactive oxygen species (ROS) which induces oxidative stress. Coenzyme Q10 (CoQ10) scavenges ROS and protects cells against oxidative stress. The present study was designed to examine whether the protection of Coenzyme Q10 against oxidative damage in astrocytes is through regulating ERK 1/2 pathway. Ultraviolet B (UVB) irradiation was chosen as a tool to induce oxidative stress. Murine astrocytes were treated with 10 μg/ml and 25 μg/ml of CoQ10 for 24 h prior to UVB and maintained during UVB and 24 h post-UVB. Cell viability was evaluated by counting viable cells and MTT conversion assay. ROS production was measured using fluorescent probes. Levels of p-ERK 1/2, ERK 1/2, p-PKA, PKA were detected using immunocytochemistry and/or Western blotting. The results showed that UVB irradiation decreased the number of viable cells. This damaging effect was associated with accumulation of ROS and elevations of p-ERK 1/2 and p-PKA. Treatment with CoQ10 at 25 μg/ml significantly increased the number of viable cells and prevented the UVB-induced increases of ROS, p-ERK 1/2, and p-PKA. It is concluded that suppression of the PKA-ERK 1/2 signaling pathway may be one of the important mechanisms by which CoQ10 protects astrocytes from UVB-induced oxidative damage.

Phenylephrine Alleviates 131I Radiation Damage in Submandibular Gland Through Maintaining Mitochondrial Homeostasis

PURPOSE

The impairment of the salivary glands is a permanent side effect of ¹³¹I ablation therapy for patients with differentiated thyroid cancer. Effective and safe treatments for protecting the salivary glands against ¹³¹I are currently not available. Mitochondria are susceptible to ionizing radiation, but alterations after ¹³¹I exposure are unknown. Here, we investigated the mechanisms of ¹³¹I damage in submandibular glands (SMGs) and evaluated the cytoprotective effect of phenylephrine (PE) against mitochondrial radiation damage.

METHODS AND MATERIALS

Rats were randomly divided into 4 groups: control, PE alone, ¹³¹I alone, and ¹³¹I with PE pretreatment. The mitochondrial structure of SMGs was observed under transmission electron microscopy. Apoptosis was detected using terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling. Cytochrome c, cleaved-caspase 3, SIRT1, NAMPT, and PGC-1α protein levels were determined with Western blot and immunohistochemistry. Levels of mitochondrial membrane potential, nicotinamide adenine dinucleotide (NAD), and adenosine triphosphate (ATP) were measured with relevant kits.

RESULTS

After exposing rat SMGs to ¹³¹I, the mitochondrial membrane structures were destroyed, the mitochondrial membrane potential decreased, the release of cytochrome c increased, and cleaved-caspase 3 and cell apoptosis were activated. Moreover, the expression of SIRT1, NAMPT, and PGC-1α was downregulated, and the levels of NAD and ATP decreased. In contrast, PE alleviated the ¹³¹I-induced mitochondrial damages and upregulated the expression of SIRT1/NAMPT/PGC-1α and the levels of NAD and ATP.

CONCLUSIONS

These findings demonstrate that ¹³¹I impairs the salivary glands via the downregulation of SIRT1/NAMPT/PGC-1α signal pathways, which disturbs mitochondrial homeostasis. PE alleviated the ¹³¹I damage in SMGs at the mitochondrial level, suggesting that PE could be used as a potential radioprotector for patients with differentiated thyroid cancer with radiation sialadenitis.

A monoclonal antibody targeted to the functional peptide of αB-crystallin inhibits the chaperone and anti-apoptotic activities

αB-Crystallin is a member of the small heat shock protein family. It is a molecular chaperone and an anti-apoptotic protein. Previous studies have shown that the peptide (⁷³DRFSVNLDVKHFSPEELKVKV⁹³, hereafter referred to as peptain-1) from the core domain of αB-crystallin exhibits both chaperone and anti-apoptotic properties similar to the parent protein. We developed a mouse monoclonal antibody against peptain-1 with the aim of blocking the functions of αB-crystallin. The antibody reacted with peptain-1, it did not react with the chaperone peptide of αA-crystallin. The antibody strongly reacted with human recombinant αB-crystallin but weakly with Hsp20; it did not react with αA-crystallin or Hsp27. The antibody specifically reacted with αB-crystallin in human and mouse lens proteins but not with αA-crystallin. The antibody reacted with αB-crystallin in human lens epithelial cells, human retinal endothelial cells, and with peptain-1 in peptain-1-transduced cells. Unlike the commercial antibodies against αB-crystallin, the antibody against peptain-1 inhibited the chaperone and anti-apoptotic activities of peptain-1. The antibody might find use in inhibiting αB-crystallin's chaperone and anti-apoptotic activities in diseases where αB-crystallin is a causative or contributing factor.

New evidences for a role of mGluR7 in astrocyte survival: Possible implications for neuroprotection

A specific activation of metabotropic glutamate receptor 7 (mGluR7) has been shown to be neuroprotective in various models of neuronal cell damage, however, its role in glia cell survival has not been studied, yet. Thus, we performed comparative experiments estimating protective effects of the mGluR7 allosteric agonist AMN082 in glia, neuronal and neuronal-glia cell cultures against various harmful stimuli. First, the transcript levels of mGluR7 and other subtypes of group II and III mGluRs in cortical neuronal, neuronal-glia and glia cell cultures have been measured by qPCR method. Next, we demonstrated that AMN082 with similar efficiency attenuated the glia cell damage evoked by staurosporine (St) and doxorubicin (Dox). The AMN082-mediated glioprotection was mGluR7-dependent and associated with decreased DNA fragmentation without involvement of caspase-3 inhibition. Moreover, the inhibitors of PI3K/Akt and MAPK/ERK1/2 pathways blocked the protective effect of AMN082. In neuronal and neuronal-glia cell cultures in the model of glutamate (Glu)- but not St-evoked cell damage, we showed a significant glia contribution to mGluR7-mediated neuroprotection. Finally, by using glia and neuronal cells derived from mGluR7+/+ and mGluR7-/- mice we demonstrated a higher cell-damaging effect of St and Dox in mGluR7-deficient glia but not in neurons (cerebellar granule cells). Our present data showed for the first time a glioprotective potential of AMN082 underlain by mechanisms involving the activation of PI3K/Akt and MAPK/ERK1/2 pathways and pro-survival role of mGluR7 in glia cells. These findings together with the confirmed neuroprotective properties of AMN082 justify further research on mGluR7-targeted therapies for various CNS disorders.

Small heat shock proteins and neurodegeneration: recent developments

Members of the small heat shock protein (sHSP) family are molecular chaperones with a critical role in the maintenance of cellular homeostasis under unfavorable conditions. The chaperone properties of sHSPs prevent protein aggregation, and sHSP deregulation underlies the pathology of several diseases, including neurodegenerative disorders. Recent evidence suggests that the clientele of sHSPs is broad, and the mechanisms of sHSP-mediated neuroprotection diverse. Nonetheless, the crosstalk of sHSPs with the neurodegeneration-promoting signaling pathways remains poorly understood. Here, we survey recent findings on the role and regulation of sHSPs in neurodegenerative diseases.

17β-Estradiol on the Expression of G-Protein Coupled Estrogen Receptor (GPER/GPR30) Mitophagy, and the PI3K/Akt Signaling Pathway in ATDC5 Chondrocytes In Vitro

Background

Osteoarthritis is a progressive inflammatory joint disease resulting in damage to articular cartilage. G-protein coupled estrogen receptor (GPER/GPR30) activates cell signaling in response to 17β-estradiol, which can be blocked by the GPR30 agonist, G15, an analog of G-1. The aims of this study were to investigate the effects of 17β-estradiol on the expression of G-protein coupled estrogen receptor (GPER/GPR30) on mitophagy and the PI3K/Akt signaling pathway in ATDC5 chondrocytes in vitro.

Material/Methods

Cultured ATDC5 chondrocytes were treated with increasing concentrations of 17β-estradiol with and without G15, p38 inhibitor (SB203580), JNK inhibitor (SP600125), PI3K inhibitor (LY294002, S1737), and mTOR inhibitor (S1842). Expression of GPER/GPR30 and components of the PI3K/Akt pathway in cultured ATDC5 chondrocytes were detected by immunofluorescence (IF) staining, Western blot, and real-time polymerase chain reaction (RT-PCR). Transmission electron microscopy (TEM) and IF were used to detect mitophagosomes. Expression of LC-3, LAMP2, TOM20, Hsp60, p-Akt, p-mTOR, p-p38, and p-JNK was investigated by Western blot. Proliferation and viability of the ATDC5 chondrocytes were determined using BrdU and MTT assays.

Results

In 17β-estradiol-treated ATDC5 chondrocytes, increased expression of GPER/GPR30 was found, but fewer mitophagosomes were observed, and decreased numbers of TOM20-positive granules were co-localized with decreased LAMP2 and increased expression levels of TOM20, Hsp60, p-Akt, and p-mTOR, and reduced expression of LC3-II, were found. In 17β-estradiol-treated ATDC5 chondrocytes, the proliferation and viability of the 17β-estradiol-treated ATDC5 chondrocytes were significantly elevated.

Conclusions

Treatment with 17β-estradiol protected ATDC5 chondrocytes against mitophagy via the GPER/GPR30 and the PI3K/Akt signaling pathway.

Murine neutrophils treated with alphaB-crystallin reduce IL-12p40 production by dendritic cells

Neutrophils are essential in the fight against invading pathogens. They utilize antimicrobial effector mechanisms, such as phagocytosis, release of proteases and other antimicrobial products, robust oxidative bursts and neutrophil extracellular traps to combat infections. Neutrophils also modulate immune responses through the production of eicosanoids, cytokines and chemokines, as well as via direct communication with other immune cells. This system of high-intensity offense against pathogens is exquisitely balanced through regulation to limit damage to host tissue. Unfortunately, the control of neutrophils is not failproof. In cases of sterile injury, autoimmunity and even during an infection, neutrophils can cause tissue destruction and become detrimental to the host. For that reason, there is a need to find means to regulate the aberrant activation of these cells. We found that alphaB-crystallin (αBC), a heat-shock protein known to have anti-inflammatory abilities, affects certain properties of mouse neutrophils that subsequently influence the pro-inflammatory state of antigen-presenting cells (APCs). More specifically, αBC mediated small but significant increases in the levels of IL-10 and matrix metalloproteinase 8, and altered hydrogen peroxide secretion by stimulated neutrophils. Further, the heat-shock protein influenced the communication between neutrophils and dendritic cells by decreasing the production of pro-inflammatory cytokines, specifically IL-12p40, by the APCs. αBC could thus contribute to dampening neutrophil inflammatory responses by impacting the effect of neutrophils on other immune cells.

Insights into Macrophage Autophagy in Latent Tuberculosis Infection: Role of Heat Shock Protein 16.3

Tuberculosis (TB) is a major bacterial infectious disease worldwide that is predominantly caused by Mycobacterium tuberculosis (Mtb). The comorbidity of multiple drug-resistant TB strains with HIV and diabetes is widespread. In the presence of these diseases, host immunity is weakened, allowing the recovery of dormant bacilli and leading to recurrent TB infection. As an important component of the host innate and adaptive immune responses, macrophage autophagy plays a significant role in protecting the host against TB. However, dormant bacilli can escape from autophagosomes and/or suppress autophagy, thus surviving within the host for an extended period of time, although the underlying mechanism remains elusive. Heat shock protein 16.3 (Hsp16.3, HspX, Rv2031c, and Acr) is one of the immunodominant proteins expressed during latent TB infection (LTBI). It may help maintain the protein stability and long-term viability of Mtb by inhibiting macrophage autophagy, resulting in LBTI. In this review, we discuss how dormant bacilli escape from autophagosomes, and we focus on the role of Hsp16.3 in regulating macrophage autophagy in LTBI so as to provide a firm basis for further studies. Hsp16.3 may represent a potential biomarker of LTBI and novel pharmacological target for anti-tubercular drugs.

The small heat shock proteins, especially HspB4 and HspB5 are promising protectants in neurodegenerative diseases

Small heat shock proteins (sHsps) are a group of proteins with molecular mass between 12 and 43 kDa. Currently, 11 members of this family have been classified, namely HspB1 to HspB11. HspB1, HspB2, HspB5, HspB6, HspB7, and HspB8, which are expressed in brain have been observed to be related to the pathology of neurodegenerative diseases, including Parkinson's, Alzheimer's, Alexander's disease, multiple sclerosis, and human immunodeficiency virus-associated dementia. Specifically, sHsps interact with misfolding and damaging protein aggregates, like Glial fibrillary acidic protein in AxD, β-amyloid peptides aggregates in Alzheimer's disease, Superoxide dismutase 1 in Amyotrophic lateral sclerosis and cytosine-adenine-guanine/polyglutamine (CAG/PolyQ) in Huntington's disease, Spinocerebellar ataxia type 3, Spinal-bulbar muscular atrophy, to reduce the toxicity or increase the clearance of these protein aggregates. The degree of HspB4 expression in brain is still debated. For neuroprotective mechanisms, sHsps attenuate mitochondrial dysfunctions, reduce accumulation of misfolded proteins, block oxidative/nitrosative stress, and minimize neuronal apoptosis and neuroinflammation, which are molecular mechanisms commonly accepted to mirror the progression and development of neurodegenerative diseases. The increasing incidence of the neurodegenerative diseases enhanced search for effective approaches to rescue neural tissue from degeneration with minimal side effects. sHsps have been found to exert neuroprotective functions. HspB5 has been emphasized to reduce the paralysis in a mouse model of experimental autoimmune encephalomyelitis, providing a therapeutic basis for the disease. In this review, we discuss the current understanding of the properties and the mechanisms of protection orchestrated by sHsps in the nervous system, highlighting the promising therapeutic role of sHsps in neurodegenerative diseases.

Sevoflurane Post-conditioning Enhanced Hippocampal Neuron Resistance to Global Cerebral Ischemia Induced by Cardiac Arrest in Rats through PI3K/Akt Survival Pathway

The purpose of this current study was to evaluate whether improvement of mitochondrial dysfunction was involved in the therapeutic effect of sevoflurane post-conditioning in global cerebral ischemia after cardiac arrest (CA) via the PI3K/Akt pathway. In the first experiment, animals were randomly divided into three groups: a sham group, a CA group, a CA+sevoflurane post-conditioning group (CA+SE). Sevoflurane post-conditioning was achieved by administration of 2.5% sevoflurane for 30 min after resuscitation. Sevoflurane post-conditioning has a significant neuroprotective effect by increasing survival rates and reducing neuronal apoptosis. Additionally, the gene and protein expression of PGC-1α, NRF-1, and TFAM, the master regulators of mitochondrial biogenesis, were up-regulated in the CA+SE group, when compared to the CA group. Similarly, in contrast to the CA group, mitochondria-specific antioxidant enzymes, including heat-shock protein 60 (HSP60), peroxiredoxin 3 (Prx3), and thioredoxin 2 (Trx2) were also increased in the CA+SE group. Finally, administration of sevoflurane ameliorated mitochondrial reactive oxygen species (ROS) formation and maintained mitochondrial integrity. In the second experiment, we investigated the relationship between the PI3K/Akt pathway and mitochondrial biogenesis and mitochondria-specific antioxidant enzymes in sevoflurane-induced neuroprotection. The selective PI3K inhibitor wortmannin not only eliminated the beneficial biochemical processes of sevoflurane by reducing the level of mitochondrial biogenesis-related proteins and aggravating mitochondrial integrity, but also reversed the elevation of mitochondria-specific antioxidant enzymes induced by sevoflurane. Therefore, our data suggested that sevoflurane post-conditioning provides neuroprotection via improving mitochondrial biogenesis and integrity, as well as increasing mitochondria-specific antioxidant enzymes by a mechanism involving the PI3K/Akt pathway.

Differential phosphorylation-based regulation of αB-crystallin chaperone activity for multipass transmembrane proteins

We have previously shown that αB-crystallin (CRYAB), a small heat shock protein (sHsp) that prevents irreversible aggregation of unfolded protein by an ATP-independent chaperone activity, plays a pivotal role in the biogenesis of multipass transmembrane proteins (TMPs) assisting their folding from the cytosolic side of the endoplasmic reticulum (ER) (D'Agostino et al., 2013). Here we present evidence, based on phosphomimetic substitutions, that the three phosphorytable serine residues at position 19, 45 and 59 of CRYAB play a different regulatory role in this novel chaperone activity: S19 and S45 have a strong inhibitory effect, either alone or in combination, while S59 has not and counteracts the inhibition caused by single phosphomimetic substitutions at S19 and S45. Interestingly, all phosphomimetic substitutions determine the formation of smaller oligomeric complexes containing CRYAB, indicating that the inhibitory effect seen for S19 and S45 cannot be ascribed to the reduction of oligomerization frequently associated to a decreased chaperone activity. These results indicate that phosphorylation finely regulates the chaperone activity of CRYAB with multipass TMPs and suggest a pivotal role for S59 in this process.

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CRYAB chaperone activity toward ATP7B-H1069Q and Fz4-FEVR.

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Phosphomimetic S19D and S45D inhibit CRYAB chaperone activity.

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Phosphomimetic S59D protects CRYAB chaperone activity.

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Pseudo-phosphorylation decreases CRYAB oligomerization.

Metabotropic glutamate receptor 1 promotes cementoblast proliferation via MAP kinase signaling pathways

PURPOSE/AIM

Glutamate is one of the signaling molecules responsible for transmission in the central nervous system. Periodontal ligament (PDL) cells were recently reported to express metabotropic glutamate receptors (mGluRs). However, the functions of mGluR signaling in PDL cells or PDL-related cells remain largely unknown. The aim of this study was to investigate the expression and function of mGluRs in PDL-related cells.

MATERIALS AND METHODS

OCCM-30 cells, immortalized murine cementoblasts, were stimulated with l-glutamate or mGluRs antagonists. The cells' proliferative response was evaluated using a colorimetric assay and gene expression was assessed using real-time polymerase chain reaction. The nuclear translocation of cyclin D1 was evaluated by immunohistochemistry.

RESULTS

l-Glutamate promoted the proliferation of OCCM-30 cells, which expressed mGluR1, but not mGluR5. Dihydroxyphenylglycine (DHPG), an agonist of group I mGluRs (mGluR1 and mGluR5), also promoted cell proliferation, and this was inhibited by LY456236, an mGluR1 antagonist. DHPG increased the expression of cyclin D1, a key regulator of cell proliferation, and its nuclear translocation. DHPG also increased the expression of Bcl2A1, an antiapoptotic oncogene and simultaneously reduced the expression of Bax, a pro-apoptotic marker. Furthermore, the DHPG-induced proliferation of OCCM-30 cells was reduced by pretreatment with SB203580, SP600125, and PD98059, inhibitors of p38, JNK, and ERK1/2, respectively.

CONCLUSIONS

These findings indicate that activation of mGluR1 expressed by OCCM-30 cells induces cell proliferation in a manner that is dependent on mitogen-activated protein kinase pathways and that cyclin D1 and Bcl2A1/Bax may be involved. Our results provide useful information for elucidating the mechanisms underlying cementum homeostasis and regeneration.

Mitochondrial dysfunction and cell death in neurodegenerative diseases through nitroxidative stress

Mitochondria are important for providing cellular energy ATP through the oxidative phosphorylation pathway. They are also critical in regulating many cellular functions including the fatty acid oxidation, the metabolism of glutamate and urea, the anti-oxidant defense, and the apoptosis pathway. Mitochondria are an important source of reactive oxygen species leaked from the electron transport chain while they are susceptible to oxidative damage, leading to mitochondrial dysfunction and tissue injury. In fact, impaired mitochondrial function is commonly observed in many types of neurodegenerative diseases, including Alzheimer's disease, Parkinson's disease, Huntington's disease, alcoholic dementia, brain ischemia-reperfusion related injury, and others, although many of these neurological disorders have unique etiological factors. Mitochondrial dysfunction under many pathological conditions is likely to be promoted by increased nitroxidative stress, which can stimulate post-translational modifications (PTMs) of mitochondrial proteins and/or oxidative damage to mitochondrial DNA and lipids. Furthermore, recent studies have demonstrated that various antioxidants, including naturally occurring flavonoids and polyphenols as well as synthetic compounds, can block the formation of reactive oxygen and/or nitrogen species, and thus ultimately prevent the PTMs of many proteins with improved disease conditions. Therefore, the present review is aimed to describe the recent research developments in the molecular mechanisms for mitochondrial dysfunction and tissue injury in neurodegenerative diseases and discuss translational research opportunities.