Immunostimulatory effects of Hsp70 fragments and Hsp27 in design of novel HIV-1 vaccine formulations

BACKGROUND

Heat shock proteins (HSPs) as an adjuvant induce antigen-specific immunity through facilitating antigen presentation and stimulating T cells. In this study, the immunostimulatory properties of two major fragments of Hsp70 (N-Hsp70(aa 1-387) with ATPase property and C-Hsp70 (aa 508-641) with peptide-binding capacity) and the full length of Hsp27 as vaccine adjuvants were evaluated to boost HIV-1 Nef antigen-specific immunity in both in vitro and in vivo experiments.

METHODS

At first, the nanoparticles harbouring DNA fusion constructs (i.e. N-Hsp70-Nef, C-Hsp70-Nef and Hsp27-Nef) complexed with HIV Rev (34-50) cell-penetrating peptide were generated to deliver DNA into the cells. Then, the recombinant Nef, Hsp27-Nef, N-Hsp70-Nef and C-Hsp70-Nef proteins were generated in E.coli expression system. Next, the immunostimulatory properties of these fusion constructs were evaluated in both in vitro and in vivo studies. Finally, the secretion of main cytokines from single-cycle replicable (SCR) HIV-1 virion-exposed splenocytes was investigated.

RESULTS

Our data showed that the stable and non-toxic DNA/Rev nanoparticles could successfully deliver the genes of interest into the cells. Moreover, higher secretion of antibodies and cytokines was detected in mice receiving the Hsp-Nef constructs than in mice receiving Nef antigen. The C-Hsp70 was also superior for inducing Nef-specific Th1 and CTL immunity compared with N-Hsp70 and Hsp27. The T-cell activity was maintained in the SCR-exposed splenocytes, especially the splenocytes of mice receiving the C-Hsp70-Nef regimen.

CONCLUSION

Altogether, these findings demonstrate the significance of Hsps as enhancers of antigen-specific immunity. Notably, the C-Hsp70 region showed better adjuvant properties for inducing cellular immunity in the improvement of HIV-1 therapeutic vaccines.

Hsp27 over expression protect against cadmium induced nephrotoxicity in Drosophila melanogaster

Cadmium (Cd) exposure to the animals including humans is reported as nephrotoxic compounds i.e., disturbing redox status (increase oxidative stress), mitochondrial dysfunction, renal cell death and altered transporters in the renal system. Hsp27 (a small heat shock protein) has been shown as one of the modulators in the renal dysfunction and increased against the Cd induced toxicity. However, no studies are reported on the genetic modulation of stress protein against the Cd-induced nephrotoxicity. The current study aimed to examine the protective role of hsp27 overexpression against the Cd-induced nephrotoxicity using Drosophila melanogaster as an animal model. D. melanogaster renal system includes nephrocytes and Malpighian tubules (MTs) that show the functional similarity with mammalian kidney nephron. Overexpression of the hsp27 was found to reduce the Cd induced oxidative stress, rescue cell death in MTs of Cd exposed D. melanogaster larvae. The rescued GSH level, NADPH level and glucose 6 phosphate dehydrogenase (G6PD) activity were also observed in the MTs of the Cd exposed organism. Function (efflux activity and fluid secretion rate) of the MTs was restored in Cd exposed hsp27 overexpressed larvae. Further, results were confirmed by restored brush border microvilli density and reduced uric acid level. Tissue specific knockdown of hsp27 developed Cd like phenotypes in MTs and the phenotypes enhanced in Cd exposed condition. The present study clearly shows the role of hsp27 overexpression in restoration of the MTs function and protection against the Cd induced renal toxicity.

The heat shock protein Hsp27 controls mitochondrial function by modulating ceramide generation

Sphingolipids have key functions in membrane structure and cellular signaling. Ceramide is the central molecule of the sphingolipid metabolism and is generated by ceramide synthases (CerS) in the de novo pathway. Despite their critical function, mechanisms regulating CerS remain largely unknown. Using an unbiased proteomics approach, we find that the small heat shock protein 27 (Hsp27) interacts specifically with CerS1 but not other CerS. Functionally, our data show that Hsp27 acts as an endogenous inhibitor of CerS1. Wild-type Hsp27, but not a mutant deficient in CerS1 binding, inhibits CerS1 activity. Additionally, silencing of Hsp27 enhances CerS1-generated ceramide accumulation in cells. Moreover, phosphorylation of Hsp27 modulates Hsp27-CerS1 interaction and CerS1 activity in acute stress-response conditions. Biologically, we show that Hsp27 knockdown impedes mitochondrial function and induces lethal mitophagy in a CerS1-dependent manner. Overall, we identify an important mode of CerS1 regulation and CerS1-mediated mitophagy through protein-protein interaction with Hsp27.

Evaluating the expression of heat shock protein 27 and topoisomerase II α in a retrospective cohort of patients diagnosed with locally advanced breast cancer and treated with neoadjuvant anthracycline-based chemotherapies

Background

Neoadjuvant anthracycline-based chemotherapy (NAC) is a major regimen for the treatment of local advanced breast cancer (LABC), while resistance to NAC remains a paramount clinical obstacle. To investigate the role of heat shock protein 27 (Hsp27) and/or topoisomerase IIα (TopoIIα) in LABC patients treated with NAC, we performed this retrospective study.

Methods

Associations of Hsp27 transcripts with clinic-pathological characteristics, survival and drug response were investigated in public databases. Hsp27-related genes were identified, followed by functional enrichment analyses. Besides, two protein-protein interaction networks were built. Then, tumors from 103 patients who were diagnosed with LABC and received NAC were collected, and Hsp27 and TopoIIα were examined by Immunohistochemistry (IHC). Chi-square or Fisher's exact tests were performed, as well as survival analyses.

Results

Either at the transcriptional level in public databases or at the protein level tested by IHC, a high level of Hsp27 was associated with aggressive tumor characteristics such as lymph node invasion and chemotherapy resistance. Hsp27-related genes mostly involved in the metabolic pathway and the gamete generation biological process. An elevated Hsp27 indicated a poor prognosis in patients with breast cancer (log-rank test P = 0.002 and 0.004 for disease-free survival [DFS] and overall survival [OS], respectively), while it might not be an independent predictor. Of note, tumors with high TopoIIα expression (TopoIIα+) was less likely to express Hsp27 (Hsp27+), in contrast to those with TopoIIα negativity (31.1% vs. 86.2%, P<0.001), and survival analyses revealed that patients with Hsp27+ and TopoIIα- tumors had a significantly lower DFS and OS (log-rank test P < 0.001 and 0.001, respectively), in contrast to the other three groups.

Conclusions

Hsp27 was associated with aggressive breast cancers and more predictable for the prognosis of LABC patients treated with NAC when concomitantly considering TopoIIα expression.

Small molecule heat shock protein 27 inhibitor J2 decreases ovarian cancer cell proliferation via induction of apoptotic pathways

Heat shock protein 27 (Hsp27) is an important member of the chaperone protein family and its overexpression promotes cancer cell survival. Here, we investigated the apoptosis inducer role of the J2 compound (Hsp27 inhibitor) in human ovarian cancer cell lines (SKOV3 and OVCAR-3). Cell proliferation was measured by MTT assay. The parameters of J2-Hsp27 interaction were determined with molecular docking calculation. The inhibitory effect of the J2 compound on Hsp27 chaperone activity was investigated by luciferase activity assay. Finally, the apoptotic inducer role of the J2 compound on SKOV3 and OVCAR-3 cells was determined by RT-PCR and caspase-3 activity assay. J2 compound decreased SKOV3 and OVCAR-3 cell proliferation in a dose-dependent manner at 48 h with IC50 values of 17.34 µM and 12.63 µM, respectively. J2 inhibited the refolding process of denatured luciferase as an Hsp27 inhibitor. Molecular docking calculation was carried out to determine the interaction between Hsp27 and J2. The results indicated that J2 selectively binds to the phosphorylation site of the Hsp27 and inhibits the phosphorylation process of Hsp27. To determine the apoptotic potential of the J2 compound against ovarian cancer cells, the mRNA expression levels of apoptotic and antiapoptotic markers (Bax, Bcl-2, Bcl-xL, Cyt-c, p53, Apaf-1, Cas-3, Cas-8, Cas-9, TNF-α, DAXX, and Ask-1) were measured using RT-PCR. While J2 increased the expressions of apoptotic genes, it decreased the expressions of anti-apoptotic genes. Further, the J2 compound increased Cas-3 activity in SKOV3 and OVCAR-3 at 5.52 and 4.12 folds, respectively. These results confirm that J2 has great potential and significance in the stimulation of apoptosis in ovarian cancer cells as an Hsp27 inhibitor.

Immunomorphological Patterns of Chaperone System Components in Rare Thyroid Tumors with Promise as Biomarkers for Differential Diagnosis and Providing Clues on Molecular Mechanisms of Carcinogenesis

Hurthle cell (HC), anaplastic (AC), and medullary (MC) carcinomas are low frequency thyroid tumors that pose several challenges for physicians and pathologists due to the scarcity of cases, information, and histopathological images, especially in the many areas around the world in which sophisticated molecular and genetic diagnostic facilities are unavailable. It is, therefore, cogent to provide tools for microscopists to achieve accurate diagnosis, such as histopathological images with reliable biomarkers, which can help them to reach a differential diagnosis. We are investigating whether components of the chaperone system (CS), such as the molecular chaperones, can be considered dependable biomarkers, whose levels and distribution inside and outside cells in the tumor tissue could present a distinctive histopathological pattern for each tumor type. Here, we report data on the chaperones Hsp27, Hsp60, and Hsp90. They presented quantitative levels and distribution patterns that were different for each tumor and differed from those of a benign thyroid pathology, goiter (BG). Therefore, the reported methodology can be beneficial when the microscopist must differentiate between HC, AC, MC, and BG.

Comparison of adjuvant effects of Montanide ISA-720 and heat shock protein 27 in increasing immunostimulatory properties of HIV-1 Nef-Vif fusion protein construct

AIM

Effective T-cell-mediated immunity has emerged as an essential component of human immunodeficiency virus-1 (HIV-1) vaccination. Thus, inducing an immune response against HIV proteins such as Nef and Vif, two major accessory proteins with critical roles in HIV pathogenesis and immune evasion, may lead to an effective approach.

INTRODUCTION

Our goal is to evaluate and compare Montanide ISA-720 and heat shock protein 27 in increasing immunostimulatory properties of HIV-1 Nef-Vif fusion protein as a vaccine candidate.

METHODS

In this study, the nef-vif fusion gene with and without the heat shock protein 27 (hsp27) gene was cloned in the prokaryotic pET24a (+) vector. Then, the recombinant Nef-Vif and Hsp27-Nef-Vif proteins were generated in the E. coli system. Finally, their immunostimulatory properties were evaluated in mice. Indeed, the potency of Hsp27 as an endogenous natural adjuvant was investigated to enhance HIV-1 Nef-Vif antigen-specific immunity compared to Montanide ISA-720 as a commercial adjuvant in protein-based immunization strategy.

RESULTS

Our results approved the role of Hsp27 as an effective adjuvant in the stimulation of B- and T-cell immunity. The linkage of Hsp27 to antigen could elicit higher levels of IgG1, IgG2a, IFN-γ, IL-5 and Granzyme B than antigen mixed with Montanide ISA-720. Moreover, the ratios of IFN-γ/ IL-5 and IgG2a/ IgG1 were significantly increased in groups receiving Nef-Vif protein + Montanide ISA-720 and Hsp27-Nef-Vif protein indicating the direction of the immune response pathway toward strong Th1 response. These ratios were higher in the group receiving Hsp27-Nef-Vif protein than in the group receiving Nef-Vif protein + Montanide ISA-720.

CONCLUSION

Our findings suggest that Hsp27 can be used as an effective adjuvant to enhance antigen-specific immune responses in HIV-1 infectious models for therapeutic vaccine development.

Inhibiting O-GlcNAcylation impacts p38 and Erk1/2 signaling and perturbs cardiomyocyte hypertrophy

The dynamic cycling of O-linked GlcNAc (O-GlcNAc) on and off Ser/Thr residues of intracellular proteins, termed O-GlcNAcylation, is mediated by the conserved enzymes O-GlcNAc transferase (OGT) and O-GlcNAcase. O-GlcNAc cycling is important in homeostatic and stress responses, and its perturbation sensitizes the heart to ischemic and other injuries. Despite considerable progress, many molecular pathways impacted by O-GlcNAcylation in the heart remain unclear. The mitogen-activated protein kinase (MAPK) pathway is a central signaling cascade that coordinates developmental, physiological, and pathological responses in the heart. The developmental or adaptive arm of MAPK signaling is primarily mediated by Erk kinases, while the pathophysiologic arm is mediated by p38 and Jnk kinases. Here, we examine whether O-GlcNAcylation affects MAPK signaling in cardiac myocytes, focusing on Erk1/2 and p38 in basal and hypertrophic conditions induced by phenylephrine. Using metabolic labeling of glycans coupled with alkyne-azide "click" chemistry, we found that Erk1/2 and p38 are O-GlcNAcylated. Supporting the regulation of p38 by O-GlcNAcylation, the OGT inhibitor, OSMI-1, triggers the phosphorylation of p38, an event that involves the NOX2-Ask1-MKK3/6 signaling axis and also the noncanonical activator Tab1. Additionally, OGT inhibition blocks the phenylephrine-induced phosphorylation of Erk1/2. Consistent with perturbed MAPK signaling, OSMI-1-treated cardiomyocytes have a blunted hypertrophic response to phenylephrine, decreased expression of cTnT (key component of the contractile apparatus), and increased expression of maladaptive natriuretic factors Anp and Bnp. Collectively, these studies highlight new roles for O-GlcNAcylation in maintaining a balanced activity of Erk1/2 and p38 MAPKs during hypertrophic growth responses in cardiomyocytes.

DDX5 mRNA-targeting antisense oligonucleotide as a new promising therapeutic in combating castration-resistant prostate cancer

The heat shock protein 27 (Hsp27) has emerged as a principal factor of the castration-resistant prostate cancer (CRPC) progression. Also, an antisense oligonucleotide (ASO) against Hsp27 (OGX-427 or apatorsen) has been assessed in different clinical trials. Here, we illustrate that Hsp27 highly regulates the expression of the human DEAD-box protein 5 (DDX5), and we define DDX5 as a novel therapeutic target for CRPC treatment. DDX5 overexpression is strongly correlated with aggressive tumor features, notably with CRPC. DDX5 downregulation using a specific ASO-based inhibitor that acts on DDX5 mRNAs inhibits cell proliferation in preclinical models, and it particularly restores the treatment sensitivity of CRPC. Interestingly, through the identification and analysis of DDX5 protein interaction networks, we have identified some specific functions of DDX5 in CRPC that could contribute actively to tumor progression and therapeutic resistance. We first present the interactions of DDX5 and the Ku70/80 heterodimer and the transcription factor IIH, thereby uncovering DDX5 roles in different DNA repair pathways. Collectively, our study highlights critical functions of DDX5 contributing to CRPC progression and provides preclinical proof of concept that a combination of ASO-directed DDX5 inhibition with a DNA damage-inducing therapy can serve as a highly potential novel strategy to treat CRPC.

Atractylenolide I inhibits EMT and enhances the antitumor effect of cabozantinib in prostate cancer via targeting Hsp27

Objective

To investigate the effect of Hsp27 and the inhibitory effect of Atractylenolide I (ATL-1) on the proliferation of prostate cancer cell DU145 and PC-3.

Methods

MTT assay was used to detect the inhibitory effect of silencing Hsp27 and ATL-1 on DU145 and PC-3 proliferation of prostate cancer cells. TUNEL detected the apoptosis rate of prostate cancer cell DU145 and PC-3 after silencing Hsp27 and ATL-1 treated. qRT-PCR was used to detect the changes of apoptosis related genes caspase-3, PARP, Bax and Bcl-2 in prostate cancer cell DU145 and PC-3 after the effect of silencing Hsp27 and ATL-1 treated. At the same time, the antitumor effect of ATL-1 combined with cabozantinib was analyzed.

Results

Hsp27 was highly expressed in human prostate cancer. MTT assay showed that ATL-1 inhibited the proliferation of prostate cancer cells DU145 and PC-3 compared with the control group. TUNEL results showed that silencing Hsp27 and ATL-1 treated could significantly promote the apoptosis of prostate cancer cells DU145 and PC-3 compared with the control group. qRT-PCR results showed that compared with the control group, ATL-1 could promote the expression of caspase-3, PARP and Bax in DU145 and PC-3 prostate cancer cells. Inhibition of Hsp27 by ATL-1 reduced cell viability and induced apoptosis. ATL-1 inhibits the antitumor effect of Hsp27 - enhanced cabozantinib. Hsp27 regulates eIF4E and mediates cell protection.

Conclusion

Silencing Hsp27 inhibits EMT. ATL-1 can inhibit the malignant evolution of prostate cancer cells by inhibiting Hsp27/eIF4E. ATL-1 also enhanced chemosensitization of cabozantinib in prostate cancer.

Targeting Heat Shock Proteins in Malignant Brain Tumors: From Basic Research to Clinical Trials

Heat shock proteins (HSPs) are conservative and ubiquitous proteins that are expressed both in prokaryotic and eukaryotic organisms and play an important role in cellular homeostasis, including the regulation of proteostasis, apoptosis, autophagy, maintenance of signal pathways, protection from various stresses (e.g., hypoxia, ionizing radiation, etc.). Therefore, HSPs are highly expressed in tumor cells, including malignant brain tumors, where they also associate with cancer cell invasion, metastasis, and resistance to radiochemotherapy. In the current review, we aimed to assess the diagnostic and prognostic values of HSPs expression in CNS malignancies as well as the novel treatment approaches to modulate the chaperone levels through the application of inhibitors (as monotherapy or in combination with other treatment modalities). Indeed, for several proteins (i.e., HSP10, HSPB1, DNAJC10, HSPA7, HSP90), a direct correlation between the protein level expression and poor overall survival prognosis for patients was demonstrated that provides a possibility to employ them as prognostic markers in neuro-oncology. Although small molecular inhibitors for HSPs, particularly for HSP27, HSP70, and HSP90 families, were studied in various solid and hematological malignancies demonstrating therapeutic potential, still their potential was not yet fully explored in CNS tumors. Some newly synthesized agents (e.g., HSP40/DNAJ inhibitors) have not yet been evaluated in GBM. Nevertheless, reported preclinical studies provide evidence and rationale for the application of HSPs inhibitors for targeting brain tumors.

Specific binding of Hsp27 and phosphorylated Tau mitigates abnormal Tau aggregation-induced pathology

Amyloid aggregation of phosphorylated Tau (pTau) into neurofibrillary tangles is closely associated with Alzheimer's disease (AD). Several molecular chaperones have been reported to bind Tau and impede its pathological aggregation. Recent findings of elevated levels of Hsp27 in the brains of patients with AD suggested its important role in pTau pathology. However, the molecular mechanism of Hsp27 in pTau aggregation remains poorly understood. Here, we show that Hsp27 partially co-localizes with pTau tangles in the brains of patients with AD. Notably, phosphorylation of Tau by microtubule affinity regulating kinase 2 (MARK2), dramatically enhances the binding affinity of Hsp27 to Tau. Moreover, Hsp27 efficiently prevents pTau fibrillation in vitro and mitigates neuropathology of pTau aggregation in a Drosophila tauopathy model. Further mechanistic study reveals that Hsp27 employs its N-terminal domain to directly interact with multiple phosphorylation sites of pTau for specific binding. Our work provides the structural basis for the specific recognition of Hsp27 to pathogenic pTau, and highlights the important role of Hsp27 in preventing abnormal aggregation and pathology of pTau in AD.

Effect of Heat Shock Preconditioning on Pressure Injury Prevention via Hsp27 Upregulation in Rat Models

Pressure injury (PI) prevention is a huge industry and involves various interventions. Temperature and moisture are important factors for wound healing; however, the active mechanism by which “moist heat” affects PI prevention has not yet been clarified. Thus, we explored the protective and therapeutic effects of hydrotherapy on PI based on the preconditioning (PC) principle, which might be useful for clinical practice. This study aimed to investigate the preventive mechanisms of heat shock preconditioning on PIs in rat models. The experiment was performed in the basic medical laboratory of Nagano College of Nursing in Japan. Ten rats were divided into two groups, with five rats in each group. Rats in the control group were not bathed. Rats in the preconditioning group (PC group) were bathed with hot tap-water. Bathing was conducted thrice a week. After bathing for 4 weeks, the PI model was constructed on the rats’ dorsal skin. The skin temperature, skin moisture, and area of ulcers were compared between the two groups. In vitro, we investigated the expression of heat shock protein 27 (Hsp27) in 6, 12, and 24 h after the PI model was constructed through Western blot analysis. Ulcers occurred in the control group 24 h after the PI model constructed, wheras the PC group exhibited ulcers after 36 h. The ulcer area was larger in the control group than that in the PC group after 24 h (all p < 0.05). The temperatures of PI wounds in the control group decreased and were lower than those in the PC group after 1, 6, 12, 36, and 48 h (all p < 0.05). However, the skin moisture levels of PI wounds increased in the control group and were higher than those in the PC group at the same time (all p < 0.05). Using Western blot analysis, hydrotherapy preconditioning showed the potential to increase Hsp27 expression after pressure was released (p < 0.05). We determine that heat shock preconditioning had a preventive effect on PIs in rat models, a result that may be associated with their actions in the upregulation of Hsp27.

Englerin A Rewires Phosphosignaling via Hsp27 Hyperphosphorylation to Induce Cytotoxicity in Renal Cancer Cells

Englerin A (EA) is a small-molecule natural product with selective cytotoxicity against renal cancer cells. EA has been shown to induce apoptosis and cell death through cell-cycle arrest and/or insulin signaling pathways. However, its biological mode of action or targets in renal cancer remains enigmatic. In this study, we employed advanced mass spectrometry-based phosphoproteomics approaches to identify EA's functional roles in renal cancer. We identified 10,940 phosphorylation sites, of which 706 sites exhibited EA-dependent phosphorylation changes. Integrated analysis of motifs and interaction networks suggested activation of stress-activated kinases including p38 upon EA treatment. Of note, a downstream target of p38, Hsp27, was found to be hyperphosphorylated on multiple sites upon EA treatment. Among these, a novel site Ser65 on Hsp27, which was further validated by targeted proteomics, was shown to be crucial for EA-induced cytotoxicity in renal cancer cells. Taken together, these data reveal the complex signaling cascade that is induced upon EA treatment and importantly provide insights into its effects on downstream molecular signaling.

HSP27 Protects Skin From Ultraviolet B -Induced Photodamage by Regulating Autophagy and Reactive Oxygen Species Production

Ultraviolet (UV) irradiation has been well documented to be linked with almost all skin problems we know, and both dermis and epidermis may be affected to varying degrees by UV irradiation. Every time when exposed to sunlight without protection, our skin will step closer to photoaging, leading to irreversible consequences ultimately. Heat shock protein 27 (HSP27) is a vital protein involved in cell growth, autophagy, apoptosis, drug resistance, tumor genesis and metastasis. Evidence suggests that the organism is subjected to various internal and external environmental stresses (heat, oxidative stress, organic toxicants, etc.), and HSP27 with high expression has protective function. However, the expression of HSP27 in coping with UV irradiation have not been examined thoroughly. In this study, photodamage models were developed through different doses of UVB irradiation in human epidermal keratinocytes (HEKs) (30 mJ/cm²), human dermal fibroblasts (HDFs) (150 mJ/cm²) and mouse skin (2,700 mJ/cm²). HSP27 knockdown decreased cell viability and increased the incidence of UVB-induced reactive oxygen species (ROS) production. We got consistent results in vivo and vitro. Compared with that in the UVB group, the expression of LC3B was significantly lower, while the expression of p62 was significantly higher in the UVB + si-HSP27 group. It was also revealed that HSP27 knockdown reduced the expressions of some antioxidants, such as superoxide dismutase (SOD) and catalase (CAT), which accelerated UVB-induced ROS release. Moreover, histological results showed that epidermis was thickened and collagen fibers were disorganized in the UVB + si-HSP27 group. These findings have demonstrated that HSP27 might play a photoprotective role in the UVB-induced skin damage process by maintaining the normal autophagy and antioxidant level. It is implied that HSP27 could be a potential therapeutic target of photodamage. However, determination of the definitive mechanism requires further exploration.

Hsp27, a potential EcR target, protects nonylphenol-induced cellular and organismal toxicity in Drosophila melanogaster

Deciphering the potential mechanism of chemical-induced toxicity enables us to alleviate the cellular and organismal dysfunction. The environmental presence of nonylphenol (endocrine disruptor) has a major health concern due to its widespread usage in our day-to-day life. The current study establishes a novel functional link among nonylphenol-induced oxidative stress, Heat shock protein 27 (Hsp27, member of stress protein family), and Ecdysone receptor (EcR, a nuclear receptor), which eventually coordinates the nonylphenol-induced sub-cellular and organismal level toxicity in a genetically tractable model Drosophila melanogaster. Drosophila larvae exposed to nonylphenol (0.05, 0.5 and 5.0 μg/mL) showed a significant decrease in Hsp27 and EcR mRNA levels in the midgut. In concurrence, reactive oxygen species (ROS) levels were increased with a corresponding decline in glutathione (GSH) level and Thioredoxin reductase (TrxR) activity. Increased lipid peroxidation (LPO), protein carbonyl (PC) contents, and cell death were also observed in a correlation with the nonylphenol concentrations. Sub-cellular toxicity poses a negative organismal response, which was evident by delayed larval development and reduced Drosophila emergence. Subsequently, a positive genetic correlation (p < 0.001) between EcR and Hsp27 revealed that nonylphenol-dependent EcR reduction is a possible link for the downregulation of Hsp27. Further, Hsp27 overexpression in midgut cells showed a reduction in nonylphenol-induced intracellular ROS, LPO, PC content, and cell death through the TrxR mediated regenerative pathway and reduced GSH level improving the organismal response to the nonylphenol exposure. Altogether, the study elucidates the potential EcR-Hsp27 molecular interactions in mitigating the nonylphenol-induced cellular and organismal toxicity.

Epinephelus coioides Hsp27 negatively regulates innate immune response and apoptosis induced by Singapore grouper iridovirus (SGIV) infection

Heat shock proteins (Hsps) are important for maintaining protein homeostasis and cell survival. In this study, Hsp27 of Epinephelus coioides, an economically important marine fish in China and Southeast Asian countries, was characterized. E. coioides Hsp27 contains the consered ACD_HspB1_like domain and three p38 MAPK phosphorylation sites, located at Thr-13, Thr-60 and Ser-167. E. coioides Hsp27 was distributed in both the cytoplasm and nucleus, its mRNA was detected in all 14 tissues examined, and its expression was up-regulated after challenge with Singapore grouper iridovirus (SGIV), an important E. coioides pathogen. Over-expression of E. coioides Hsp27 significantly upregulated the expressions of the key SGIV genes (VP19, LITAF, MCP, and ICP18), downgraded the expressions of the E. coioides immune factors (IRF3, IRF7, ISG15, and TRAF6) and proinflammatory factors (TNF-α, IL-8), downgraded the activation of nuclear factor kappa-B (NF-κB) and activator protein-1 (AP-1), and substantially inhibited the cell apoptosis induced by SGIV infection. These data illustrated that E. coioides Hsp27 might be involved in SGIV infection by negatively regulating the innate immune response.

Hsp27 and Hsp60 in human submandibular salivary gland: Quantitative patterns in healthy and cancerous tissues with potential implications for differential diagnosis and carcinogenesis

Tumors of the submandibular salivary gland (SMG) are uncommon but sufficiently frequent for the physician to consider them in routine examinations and for the pathologist to be prepared to differentiate them from other tissue abnormalities. However, scarcity of specimens makes training difficult, a situation compounded by the lack of accepted universal diagnostic guidelines. Furthermore, there is little information on the chaperone system (CS) of the gland, despite the increasing evidence of its participation in carcinogenesis as a biomarker for diagnosis and patient follow up, and in the mechanisms by which the tumor cells thrive. We are investigating this aspect of various tumors, and here we describe standardized methods for assessing the tissue levels of two chaperones, Hsp27 and Hsp60, in normal SMG and its tumors. We present illustrative results obtained with immunohistochemistry (IHC) and immunofluorescence-confocal microscopy (IF-CM), which we propose as a platform onto which a data base could be built by adding new information and which would provide material for developing guidelines for tumor identification and monitoring. The initial findings are encouraging in as much as the tumors surveyed showed quantitative patterns of Hsp27 and Hsp60 that distinguished tumoral from normal tissue and certain tumors from the others, and the results from IHC were confirmed by IF-CM.

Human Blood Serum Induces p38-MAPK- and Hsp27-Dependent Migration Dynamics of Adult Human Cardiac Stem Cells: Single-Cell Analysis via a Microfluidic-Based Cultivation Platform

Simple Summary

Adult human stem cells possess the ability to contribute to endogenous regeneration processes of injured tissue by migrating to specific locations. For stem cell-based clinical applications it is highly important to gain knowledge about the migration behavior of adult human stem cells and the underlying molecular mechanisms of this ability. Human blood serum has been shown to have beneficial effects on other regenerative capacities of adult human stem cells. Within this study we tested the effect of human blood serum on the migration behavior of stem cells from the human heart. We used a microfluidic cultivation device, which allowed us to monitor the living cells and their movement behavior in real time. After addition of human blood serum, the heart stem cells increased their speed of movement and covered distance. Further, we observed that this effect could be diminished by inhibition of a specific kinase, p38-MAPK. Thus, our data suggest beneficial effects of human blood serum on adult human heart stem cells dependent on p38-MAPK. Our study contributes to a deeper understanding of the dynamics of stem cell migration and introduces a new platform to monitor stem cell movement in real time.

Abstract

Migratory capabilities of adult human stem cells are vital for assuring endogenous tissue regeneration and stem cell-based clinical applications. Although human blood serum has been shown to be beneficial for cell migration and proliferation, little is known about its impact on the migratory behavior of cardiac stem cells and underlying signaling pathways. Within this study, we investigated the effects of human blood serum on primary human cardiac stem cells (hCSCs) from the adult heart auricle. On a technical level, we took advantage of a microfluidic cultivation platform, which allowed us to characterize cell morphologies and track migration of single hCSCs via live cell imaging over a period of up to 48 h. Our findings showed a significantly increased migration distance and speed of hCSCs after treatment with human serum compared to control. Exposure of blood serum-stimulated hCSCs to the p38 mitogen-activated protein kinase (p38-MAPK) inhibitor SB239063 resulted in significantly decreased migration. Moreover, we revealed increased phosphorylation of heat shock protein 27 (Hsp27) upon serum treatment, which was diminished by p38-MAPK-inhibition. In summary, we demonstrate human blood serum as a strong inducer of adult human cardiac stem cell migration dependent on p38-MAPK/Hsp27-signalling. Our findings further emphasize the great potential of microfluidic cultivation devices for assessing spatio-temporal migration dynamics of adult human stem cells on a single-cell level.

Involvement of PI3K Pathway in Glioma Cell Resistance to Temozolomide Treatment

The aim of the study was to investigate the anticancer potential of LY294002 (PI3K inhibitor) and temozolomide using glioblastoma multiforme (T98G) and anaplastic astrocytoma (MOGGCCM) cells. Apoptosis, autophagy, necrosis, and granules in the cytoplasm were identified microscopically (fluorescence and electron microscopes). The mitochondrial membrane potential was studied by flow cytometry. The activity of caspases 3, 8, and 9 and Akt was evaluated fluorometrically, while the expression of Beclin 1, PI3K, Akt, mTOR, caspase 12, and Hsp27 was determined by immunoblotting. SiRNA was used to block Hsp27 and PI3K expression. Cell migration and localization of Hsp27 were tested with the wound healing assay and immunocytochemistry, respectively. LY294002 effectively diminished the migratory potential and increased programmed death of T98G and MOGGCCM. Autophagy was dominant in MOGGCCM, while apoptosis was dominant in T98G. LY294002 with temozolomide did not potentiate cell death but redirected autophagy toward apoptosis, which was correlated with ER stress. A similar effect was observed after blocking PI3K expression with siRNA. Transfection with Hsp27 siRNA significantly increased apoptosis related to ER stress. Our results indicate that inhibition of the PI3K/Akt/mTOR pathway sensitizes glioma cells to apoptosis upon temozolomide treatment, which was correlated with ER stress. Hsp27 increases the resistance of glioma cells to cell death upon temozolomide treatment.

Phenotypic Screen with TSC-Deficient Neurons Reveals Heat-Shock Machinery as a Druggable Pathway for mTORC1 and Reduced Cilia

Tuberous sclerosis complex (TSC) is a neurogenetic disorder that leads to elevated mechanistic targeting of rapamycin complex 1 (mTORC1) activity. Cilia can be affected by mTORC1 signaling, and ciliary deficits are associated with neurodevelopmental disorders. Here, we examine whether neuronal cilia are affected in TSC. We show that cortical tubers from TSC patients and mutant mouse brains have fewer cilia. Using high-content image-based assays, we demonstrate that mTORC1 activity inversely correlates with ciliation in TSC1/2-deficientneurons.To investigate the mechanistic relationship between mTORC1 and cilia, we perform a phenotypic screen for mTORC1 inhibitors with TSC1/2-deficient neurons. We identify inhibitors ofthe heat shock protein 90 (Hsp90) that suppress mTORC1 through regulation of phosphatidylinositol 3-kinase (PI3K)/Akt signaling. Pharmacological inhibition of Hsp90 rescues ciliation through downregulation of Hsp27. Our study uncovers the heat-shock machinery as a druggable signaling node to restore mTORC1 activity and cilia due to loss of TSC1/2, and it provides broadly applicable platforms for studying TSC-related neuronal dysfunction.

Di Nardo et al. find that cortical tubers from TSC patients and mutant mouse brains have fewer cilia. An image-based screening of mTORC1 activity in TSC1/2-deficient neurons leads to the identification of the heat-shock machinery as a druggable signaling node to restore mTORC1 activity and cilia.

Molecular Chaperones and Thyroid Cancer

Thyroid cancers are the most common of the endocrine system malignancies and progress must be made in the areas of differential diagnosis and treatment to improve patient management. Advances in the understanding of carcinogenic mechanisms have occurred in various fronts, including studies of the chaperone system (CS). Components of the CS are found to be quantitatively increased or decreased, and some correlations have been established between the quantitative changes and tumor type, prognosis, and response to treatment. These correlations provide the basis for identifying distinctive patterns useful in differential diagnosis and for planning experiments aiming at elucidating the role of the CS in tumorigenesis. Here, we discuss studies of the CS components in various thyroid cancers (TC). The chaperones belonging to the families of the small heat-shock proteins Hsp70 and Hsp90 and the chaperonin of Group I, Hsp60, have been quantified mostly by immunohistochemistry and Western blot in tumor and normal control tissues and in extracellular vesicles. Distinctive differences were revealed between the various thyroid tumor types. The most frequent finding was an increase in the chaperones, which can be attributed to the augmented need for chaperones the tumor cells have because of their accelerated metabolism, growth, and division rate. Thus, chaperones help the tumor cell rather than protect the patient, exemplifying chaperonopathies by mistake or collaborationism. This highlights the need for research on chaperonotherapy, namely the development of means to eliminate/inhibit pathogenic chaperones.

The effect of female sex hormones on Hsp27 phosphorylation and histological changes in prefrontal cortex after tMCAO

BACKGROUND

Female sex hormones are protective factors against many neurological disorders such as brain ischemia. Heat shock protein like HSP27 is activated after tissue injury. The main purpose of the present study is to determine the effect of a combined estrogen / progesterone cocktail on the morphology of astrocytes, neurons and Hsp27 phosphorylation after cerebral ischemia.

METHODS

One hour after the MCAO induction, a single dose of estrogen and progesterone was injected. The infarct volume was calculated by TTC staining 24 h after ischemia. Immunohistochemistry was used to show the effects of estrogen and progesterone on astrocyte and neuron morphology, as well as the Western blot technique used for the quantitation of phosphorylated Hsp27.

RESULTS

The combined dose of estrogen and progesterone significantly decreased astrocytosis after ischemia and increased neuron survival. There was a large increase in Hsp27 phosphorylation in the penumbra ischemic region after stroke, which was significantly reduced by hormone therapy.

CONCLUSION

Our results indicate that the neuroprotective effect of neurosteroids in the brain may be due to the modulation of heat shock proteins.

The Effect of Oxidized Dopamine on the Structure and Molecular Chaperone Function of the Small Heat-Shock Proteins, αB-Crystallin and Hsp27

Oxidation of the neurotransmitter, dopamine (DA), is a pathological hallmark of Parkinson’s disease (PD). Oxidized DA forms adducts with proteins which can alter their functionality. αB-crystallin and Hsp27 are intracellular, small heat-shock molecular chaperone proteins (sHsps) which form the first line of defense to prevent protein aggregation under conditions of cellular stress. In vitro, the effects of oxidized DA on the structure and function of αB-crystallin and Hsp27 were investigated. Oxidized DA promoted the cross-linking of αB-crystallin and Hsp27 to form well-defined dimer, trimer, tetramer, etc., species, as monitored by SDS-PAGE. Lysine residues were involved in the cross-links. The secondary structure of the sHsps was not altered significantly upon cross-linking with oxidized DA but their oligomeric size was increased. When modified with a molar equivalent of DA, sHsp chaperone functionality was largely retained in preventing both amorphous and amyloid fibrillar aggregation, including fibril formation of mutant (A53T) α-synuclein, a protein whose aggregation is associated with autosomal PD. In the main, higher levels of sHsp modification with DA led to a reduction in chaperone effectiveness. In vivo, DA is sequestered into acidic vesicles to prevent its oxidation and, intracellularly, oxidation is minimized by mM levels of the antioxidant, glutathione. In vitro, acidic pH and glutathione prevented the formation of oxidized DA-induced cross-linking of the sHsps. Oxidized DA-modified αB-crystallin and Hsp27 were not cytotoxic. In a cellular context, retention of significant chaperone functionality by mildly oxidized DA-modified sHsps would contribute to proteostasis by preventing protein aggregation (particularly of α-synuclein) that is associated with PD.

HSP27 role in cardioprotection by modulating chemotherapeutic doxorubicin-induced cell death

The common phenomenon expected from any anti-cancer drug in use is to kill the cancer cells without any side effects to non-malignant cells. Doxorubicin is an anthracycline derivative anti-cancer drug active over different types of cancers with anti-cancer activity but attributed to unintended cytotoxicity and genotoxicity triggering mitogenic signals inducing apoptosis. Administration of doxorubicin tends to both acute and chronic toxicity resulting in cardiomyopathy (left ventricular dysfunction) and congestive heart failure (CHF). Cardiotoxicity is prevented through administration of different cardioprotectants along with the drug. This review elaborates on mechanism of drug-mediated cardiotoxicity and attenuation principle by different cardioprotectants, with a focus on Hsp27 as cardioprotectant by prevention of drug-induced oxidative stress, cell survival pathways with suppression of intrinsic cell death. In conclusion, Hsp27 may offer an exciting/alternating cardioprotectant, with a wider study being need of the hour, specifically on primary cell line and animal models in conforming its cardioprotectant behaviour.

Androgen receptor (AR) antagonism triggers acute succinate-mediated adaptive responses to reactivate AR signaling

Treatment-induced adaptive pathways converge to support androgen receptor (AR) reactivation and emergence of castration-resistant prostate cancer (PCa) after AR pathway inhibition (ARPI). We set out to explore poorly defined acute adaptive responses that orchestrate shifts in energy metabolism after ARPI and identified rapid changes in succinate dehydrogenase (SDH), a TCA cycle enzyme with well-known tumor suppressor activity. We show that AR directly regulates transcription of its catalytic subunits (SDHA, SDHB) via androgen response elements (AREs). ARPI acutely suppresses SDH activity, leading to accumulation of the oncometabolite, succinate. Succinate triggers calcium ions release from intracellular stores, which in turn phospho-activates the AR-cochaperone, Hsp27 via p-CaMKK2/p-AMPK/p-p38 axis to enhance AR protein stabilization and activity. Activation of this pathway was seen in tissue microarray analysis on prostatectomy tissues and patient-derived xenografts. This adaptive response is blocked by co-targeting AR with Hsp27 under both in vitro and in vivo studies, sensitizing PCa cells to ARPI treatments.

p38 MAPK Inhibition Mitigates Hypoxia-Induced AR Signaling in Castration-Resistant Prostate Cancer

Simple Summary

Progression of prostate cancer to a castration-resistant state is associated with poor patient outcomes, and new therapeutic targeting approaches are needed. Poorly oxygenated (hypoxic) cancer cells are resistant to many treatment modalities, and it is therefore important that novel therapies also target these cells. Here we show that targeting the p38 MAPK protein kinase can inhibit growth and survival of both well-oxygenated and hypoxic castration resistant prostate cancer cells and prolong survival of tumor bearing mice. p38 MAPK targeting inhibited phosphorylation of the chaperone protein Hsp27 and activity of the androgen receptor. This demonstrates that prostate cancer cells can remain dependent on the p38 MAPK/Hsp27 signaling axis upon progression to castration-resistance, and that hypoxia does not offer protection against targeting this pathway.

Abstract

Background: Aberrant androgen receptor (AR) signaling is a major driver of castration-resistant prostate cancer (CRPC). Tumor hypoxia increases AR signaling and is associated with treatment resistance in prostate cancer. Heat shock protein 27 (Hsp27) is a molecular chaperone that is activated in response to heat shock and hypoxia. Hsp27 has previously been reported to facilitate AR nuclear translocation in a p38 mitogen-activated protein kinase (MAPK) dependent manner in castration-sensitive prostate cancer cell lines. Here, we evaluated the potential for inhibiting p38 MAPK/Hsp27 mediated AR signaling under normoxia and hypoxia in experimental models of CRPC. Methods: We inhibited p38 MAPK with SB203580 in prostate cancer cell lines and measured Hsp27 phosphorylation, AR activity, cell proliferation, and clonogenicity under normoxia and hypoxia. AR activity was measured using an androgen response element driven reporter assay and qPCR to measure expression of AR target genes. Xenograft-bearing mice were treated with SB203580 to measure tumor growth and serum prostate specific antigen (PSA). Results: Our results indicate that p38 MAPK and Hsp27 are activated under normoxia and hypoxia in response to androgens in CRPC cells. p38 MAPK inhibition diminished Hsp27 activation and the hypoxia-mediated increase in AR activity. Additionally, inhibition of p38 MAPK activity decreased proliferation and survival of CRPC cells in vitro and prolonged the survival of tumor-bearing mice. Conclusions: These results suggest that p38 MAPK inhibition may represent a therapeutic strategy to disrupt AR signaling in the heterogeneous CRPC tumor microenvironment.

Rapamycin Protects Skin Fibroblasts From UVA-Induced Photoaging by Inhibition of p53 and Phosphorylated HSP27

Skin aging caused by UV radiation is called photoaging is characterized by skin roughness and dryness accompanied by a significant reduction of dermal collagen. Rapamycin is a macrolide immunosuppressant which has been shown to exhibit “anti-aging” effects in cells and organisms, however, its roles in the skin photoaging remains unclear. Here, we investigate the role of rapamycin and HSP27, which we have previously identified as an inhibitor of UV-induced apoptosis and senescence in HaCat cells, in a UVA-induced photoaging model of primary human dermal fibroblasts (HDFs). Results from senescence-associated beta-galactosidase (SA-β-gal) staining revealed that rapamycin significantly reduced senescence in UVA-treated HDFs. In addition, treatment with rapamycin significantly increased cell autophagy levels, decreased the expression of p53 and phosphorylated HSP27, and reduced genotoxic and oxidative cellular stress levels in UVA-induced HDFs. Knockdown of HSP27 resulted in a significant increase of MMP-1 and MMP-3 as well as a decrease in type I collagen expression. Rapamycin mitigated these effects by activation of the classical TGF-β/Smad signaling pathway and increasing the transcriptional activity of MAPK/AP-1. Taken together, these results suggest that rapamycin may potentially serve as a preventive and therapeutic agent for UVA-induced photoaging of the skin.

Effects of the signal modulation on the response of human fibroblasts to in vitro stimulation with subthermal RF currents

Capacitive-Resistive Electric Transfer (CRET) thermotherapies aim at tissue repair and regeneration through non-invasive application of RF currents. We have reported that the cellular response to subthermal CRET currents is non-linearly dependent on the signal frequency, and that in vitro exposure to a 448-kHz CRET signal promotes ADSC proliferation, as well as collagen and glycosaminoglycan synthesis in prechondrocytic cells. The present work investigates the response of neonatal fibroblasts to subthermal exposure (100 µA/mm²) to two CRET signals: a 448-kHz, non-modulated sinusoidal wave vs. a 20-kHz amplitude-modulation of the 448-kHz carrier. To that end, cell proliferation and expression of the biomarkers Hsp47, Hsp27 and decorin were assessed by cell count, PCNA and Western blotting. The results revealed that while both signals significantly and equivalently increased early (4 h) expression of Hsp47, the modulated signal was more efficient in inducing Hsp27 and decorin overexpression and promoting cell proliferation. These data indicate that the cellular response is dependent on the RF signal modulation and suggest that the therapeutic effects of CRET could be mediated by promotion of fibroblastic proliferation and overexpression of biomarkers that are essential in skin regeneration.

N- and C-terminal regions of αB-crystallin and Hsp27 mediate inhibition of amyloid nucleation, fibril binding, and fibril disaggregation

Small heat-shock proteins (sHSPs) are ubiquitously expressed molecular chaperones that inhibit amyloid fibril formation; however, their mechanisms of action remain poorly understood. sHSPs comprise a conserved α-crystallin domain flanked by variable N- and C-terminal regions. To investigate the functional contributions of these three regions, we compared the chaperone activities of various constructs of human αB-crystallin (HSPB5) and heat-shock 27-kDa protein (Hsp27, HSPB1) during amyloid formation by α-synuclein and apolipoprotein C-II. Using an array of approaches, including thioflavin T fluorescence assays and sedimentation analysis, we found that the N-terminal region of Hsp27 and the terminal regions of αB-crystallin are important for delaying amyloid fibril nucleation and for disaggregating mature apolipoprotein C-II fibrils. We further show that the terminal regions are required for stable fibril binding by both sHSPs and for mediating lateral fibril-fibril association, which sequesters preformed fibrils into large aggregates and is believed to have a cytoprotective function. We conclude that although the isolated α-crystallin domain retains some chaperone activity against amyloid formation, the flanking domains contribute additional and important chaperone activities, both in delaying amyloid formation and in mediating interactions of sHSPs with amyloid aggregates. Both these chaperone activities have significant implications for the pathogenesis and progression of diseases associated with amyloid deposition, such as Parkinson's and Alzheimer's diseases.

Modulation of Titin-Based Stiffness in Hypertrophic Cardiomyopathy via Protein Kinase D

The giant protein titin performs structure-preserving functions in the sarcomere and is important for the passive stiffness (F_passive) of cardiomyocytes. Protein kinase D (PKD) enzymes play crucial roles in regulating myocardial contraction, hypertrophy, and remodeling. PKD phosphorylates myofilament proteins, but it is not known whether the giant protein titin is also a PKD substrate. Here, we aimed to determine whether PKD phosphorylates titin and thereby modulates cardiomyocyte F_passive in normal and failing myocardium. The phosphorylation of titin was assessed in cardiomyocyte-specific PKD knock-out mice (cKO) and human hearts using immunoblotting with a phosphoserine/threonine and a phosphosite-specific titin antibody. PKD-dependent site-specific titin phosphorylation in vivo was quantified by mass spectrometry using stable isotope labeling by amino acids in cell culture (SILAC) of SILAC-labeled mouse heart protein lysates that were mixed with lysates isolated from hearts of either wild-type control (WT) or cKO mice. F_passive of single permeabilized cardiomyocytes was recorded before and after PKD and HSP27 administration. All-titin phosphorylation was reduced in cKO compared to WT hearts. Multiple conserved PKD-dependent phosphosites were identified within the Z-disk, A-band and M-band regions of titin by quantitative mass spectrometry, and many PKD-dependent phosphosites detected in the elastic titin I-band region were significantly decreased in cKO. Analysis of titin site-specific phosphorylation showed unaltered or upregulated phosphorylation in cKO compared to matched WT hearts. F_passive was elevated in cKO compared to WT cardiomyocytes and PKD administration lowered F_passive of WT and cKO cardiomyocytes. Cardiomyocytes from hypertrophic cardiomyopathy (HCM) patients showed higher F_passive compared to control hearts and significantly lower F_passive after PKD treatment. In addition, we found higher phosphorylation at CaMKII-dependent titin sites in HCM compared to control hearts. Expression and phosphorylation of HSP27, a substrate of PKD, were elevated in HCM hearts, which was associated with increased PKD expression and phosphorylation. The relocalization of HSP27 in HCM away from the sarcomeric Z-disk and I-band suggested that HSP27 failed to exert its protective action on titin extensibility. This protection could, however, be restored by administration of HSP27, which significantly reduced F_passive in HCM cardiomyocytes. These findings establish a previously unknown role for PKDin regulating diastolic passive properties of healthy and diseased hearts.

Hsp27 reduces glycation-induced toxicity and aggregation of alpha-synuclein

α-synuclein (aSyn) is a major player in Parkinson's disease and a group of other disorders collectively known as synucleinopathies, but the precise molecular mechanisms involved are still unclear. aSyn, as virtually all proteins, undergoes a series of posttranslational modifications during its lifetime, which can affect its biology and pathobiology. We recently showed that glycation of aSyn by methylglyoxal (MGO) potentiates its oligomerization and toxicity, induces dopaminergic neuronal cell loss in mice, and affects motor performance in flies. Small heat-shock proteins (sHsps) are molecular chaperones that facilitate the folding of proteins or target misfolded proteins for clearance. Importantly, sHsps were shown to prevent aSyn aggregation and cytotoxicity. Upon treating cells with increasing amounts of methylglyoxal, we found that the levels of Hsp27 decreased in a dose-dependent manner. Therefore, we hypothesized that restoring the levels of Hsp27 in glycating environments could alleviate the pathogenicity of aSyn. Consistently, we found that Hsp27 reduced MGO-induced aSyn aggregation in cells, leading to the formation of nontoxic aSyn species. Remarkably, increasing the levels of Hsp27 suppressed the deleterious effects induced by MGO. Our findings suggest that in glycating environments, the levels of Hsp27 are important for modulating the glycation-associated cellular pathologies in synucleinopathies.

Phosphorylated Heat Shock Protein 27 Inhibits Lipopolysaccharide-Induced Inflammation in Thp1 Cells by Promoting TLR4 Endocytosis, Ubiquitination, and Degradation

The aims of this study were to investigate the effect of Hsp27 on LPS-induced inflammation and identify the precise mechanisms about how Hsp27 regulates LPS-induced TLR4 signaling in Thp1 cells. Thp1 cells were transfected with Flag-Hsp27 or pcDNA3.1, and then treated with LPS for indicated time. TNF-α, IL-1β, and IL-6 were determined by ELISA. The protein levels of Hsp27, p-Hsp27 (Ser15, Ser78, and Ser82), and TLR4 were measured by Western blotting. In vitro study showed that over-expression of Hsp27 downregulated the release of TNF-α, IL-1β, and IL-6 and suppressed the activation of TLR4 signals after stimulated by LPS. The location of TLR4 and RAB5 was detected by confocal microscopy. Immunoprecipitation was used to determine the ubiquitination and degradation of TLR4 and interaction between Hsp27 and TLR4. Results showed that Hsp27 could promote TLR4 endocytosis and ubiquitination and degradation. Further research revealed that Hsp27 was phosphorylated after LPS, only phosphorylated Hsp27 can interact with TLR4 and inhibit the activation of TLR4 signaling, which was demonstrated by inhibition of Hsp27 phosphorylation with inhibitors or transfection of Hsp27 mutants into Thp1 cells. Phosphorylated Hsp27 reduced the release of TNF-α, IL-1β, and IL-6, and suppressed the activation of TLR4 signaling by promoting TLR4 endocytosis, ubiquitination, and degradation.

Release of a disordered domain enhances HspB1 chaperone activity toward tau

Small heat shock proteins (sHSPs) are a class of ATP-independent molecular chaperones that play vital roles in maintaining protein solubility and preventing aberrant protein aggregation. They form highly dynamic, polydisperse oligomeric ensembles and contain long intrinsically disordered regions. Experimental challenges posed by these properties have greatly impeded our understanding of sHSP structure and mechanism of action. Here we characterize interactions between the human sHSP HspB1 (Hsp27) and microtubule-associated protein tau, which is implicated in multiple dementias, including Alzheimer's disease. We show that tau binds both to a well-known binding groove within the structured alpha-crystallin domain (ACD) and to sites within the enigmatic, disordered N-terminal region (NTR) of HspB1. However, only interactions involving the NTR lead to productive chaperone activity, whereas ACD binding is uncorrelated with chaperone function. The tau-binding groove in the ACD also binds short hydrophobic regions within HspB1 itself, and HspB1 mutations that disrupt these intrinsic ACD-NTR interactions greatly enhance chaperone activity toward tau. This leads to a mechanism in which the release of the disordered NTR from a binding groove on the ACD enhances chaperone activity toward tau. The study advances understanding of the mechanisms by which sHSPs achieve their chaperone activity against amyloid-forming clients and how cells defend against pathological tau aggregation. Furthermore, the resulting mechanistic model points to ways in which sHSP chaperone activity may be increased, either by native factors within the cell or by therapeutic intervention.

Methylglyoxal Scavengers Resensitize KRAS-Mutated Colorectal Tumors to Cetuximab

The use of cetuximab anti-epidermal growth factor receptor (anti-EGFR) antibodies has opened the era of targeted and personalized therapy in colorectal cancer (CRC). Poor response rates have been unequivocally shown in mutant KRAS and are even observed in a majority of wild-type KRAS tumors. Therefore, patient selection based on mutational profiling remains problematic. We previously identified methylglyoxal (MGO), a by-product of glycolysis, as a metabolite promoting tumor growth and metastasis. Mutant KRAS cells under MGO stress show AKT-dependent survival when compared with wild-type KRAS isogenic CRC cells. MGO induces AKT activation through phosphatidylinositol 3-kinase (PI3K)/mammalian target of rapamycin 2 (mTORC2) and Hsp27 regulation. Importantly, the sole induction of MGO stress in sensitive wild-type KRAS cells renders them resistant to cetuximab. MGO scavengers inhibit AKT and resensitize KRAS-mutated CRC cells to cetuximab in vivo. This study establishes a link between MGO and AKT activation and pinpoints this oncometabolite as a potential target to tackle EGFR-targeted therapy resistance in CRC.

Differential Nasal Expression of Heat Shock Proteins 27 and 70 by Aerobic Exercise: A Preliminary Study

Purpose: Exercise modifies airway immune responses and susceptibility to infection. We investigated the effects of exercise on two HSPs (heat shock proteins), quantifying expression levels in nasal mucosa of both professional competitive athletes and non-athletes for comparison. Method: We used western blot technique to determine expression levels of HSPs in primary human nasal epithelial cells (HNECs). Nasal lavage (NAL) fluids were collected from 12 male professional volley ball players and 6 healthy males pre-submaximal exercise (running for 30 min at 70-80% of maximal heart rate) and post-submaximal exercise. Expression levels of HSP27, HSP70, Interleukin (IL)-8, and Tumor necrosis factor (TNF)-α in NAL fluids were quantified by enzyme-linked immunosorbent assay (ELISA), and difference of the level between pre-submaximal exercise and post-submaximal exercise was statistically analyzed. Antibacterial assay using Staphylococcus aureus was performed to assess the immunological role of HSPs in NAL fluids. Results:. In non-athlete controls, HSP27, HSP70, and IL-8 were unchanged after exercise. In the professional athletes, HSP70 expression was declined significantly (p<0.05), but HSP27 was not significantly changed. IL-8 and TNF-α did not show significant difference, either. By antibacterial assay, it was found that the number of active bacterial populations were influenced by the presence or absence of HSP27 and HSP70 in NAL fluids. Conclusion: HSP27 and HSP70 were present in NAL fluids of enrolled subjects, and the effect of exercise on the level HSPs was different between professional athletic competitors and non-athletes. As the number of active bacterial population was influenced by the presence or absence of nasal HSP27 and HSP70, we suggest that HSP27 and HSP70 may play immunological function in NAL fluids.

Phosphorylated Hsp27 prevents LPS-induced excessive inflammation in THP-1 cells via suppressing ROS-mediated upregulation of CBP

Heat shock protein 27 (Hsp27) is a member of the small heat shock protein family expressed at high levels to protect cells against heat shock and other conditions of stress. Hsp27 has been indicated in the regulation of inflammation signaling pathway, and Hsp27 phosphorylation is vital for efficient control of host-defense response in early stages of lipopolysaccharide (LPS)-stimulated inflammation. The notion that CREB-binding protein (CBP) is involved in the regulation of two major transcription factors, nuclear factor-κB (NF-κB) and AP-1, suggests that CBP, as a coactivator protein, may also play an important role in the cellular response to inflammation. Here, we explored the mechanism underlying the regulatory relationships between Hsp27 and CBP in THP-1 cells, and found that phosphorylated Hsp27 was critical to the protein level of CBP. Furthermore, in exploring the signaling mechanisms underlying its action, we found that p38MAPK-MK2-Hsp27 regulated NF-κB via CBP, which acted as a multi-protein complex assembly scaffold. Finally, we demonstrated that phosphorylated Hsp27 reduced reactive oxygen species accumulation thereby significantly repressed LPS-induced excessive increase of CBP. Taken together, our data demonstrated that Hsp27, in its phosphorylation state, plays a critical role in controlling LPS-induced inflammatory response by modulating CBP.

Cardiac Noradrenaline Turnover and Heat Shock Protein 27 Phosphorylation in Dyskinetic Monkeys

BACKGROUND

Autonomic dysfunction is a well-known dominant symptom in the advanced stages of Parkinson's disease. However, the role of cardiac sympathetic nerves still needs to be elucidated.

OBJECTIVES

To evaluate cardiac sympathetic response in Parkinsonian and dyskinetic monkeys.

METHODS

Adult male monkeys were divided into 1 of the following 3 groups: controls, 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine-treated monkeys, and 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine+levodopa-treated animals. Noradrenaline, its metabolite normetanephrine, and phospho-Heat shock proten 27 (p-Hsp27) at serine 82 levels were analyzed in the left and right ventricles of the heart. Tyrosine hydroxylase immunohistochemistry was performed in the ventral mesencephalon.

RESULTS

The results were the following: (1) 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine intoxication significantly increased normetanephrine levels and decreased noradrenaline turnover in the right ventricle without changes in the left ventricle; however, (2) levodopa treatment decreased noradrenaline levels and enhanced the normetanephrine/noradrenaline ratio in parallel with a very significant increase of Hsp27 activity in both ventricles.

CONCLUSIONS

Levodopa treatment could induce protective cardiac effects through the increased Hsp27 activity. © 2019 International Parkinson and Movement Disorder Society.

Heat shock protein 27 as a neuroprotective biomarker and a suitable target for stem cell therapy and pharmacotherapy in ischemic stroke

Ischemic stroke is a major common cause of death and long-term disability worldwide. Several pathophysiological events including excitotoxicity, oxidative/nitrative stress, inflammation, and apoptosis are involved in ischemic injuries. Recently, the molecular mechanisms involved in cerebral ischemia through a focus on a member of small heat shock proteins family, Hsp27, has been developed. Notably, following exposure to ischemia, Hsp27 expression in the brain could be increased rather than the normal condition and it may play an important role in neuroprotection after ischemic stroke. The neuroprotection effects of Hsp27 may arise from its anti-oxidant, anti-inflammatory, anti-apoptotic, and chaperonic properties. Moreover, some therapeutic strategies such as stem cell therapy and pharmacotherapy have been developed with Hsp27 targeting. In this review, we describe the function and structure of Hsp27 and its possible role in neuroprotection after ischemic stroke. Finally, we present current studies in stroke therapy, which focused on Hsp27 targeting.

Resveratrol and siRNA in combination reduces Hsp27 expression and induces caspase-3 activity in human glioblastoma cells

GBM cells can easily gain resistance to conventional therapy, and therefore treatment of glioblastoma multiforme (GBM) is difficult. One of the hallmark proteins known to be responsible for this resistance is heat shock protein 27 (Hsp27) which has a key role in the cell survival. Resveratrol, a natural compound, exhibits antitumor effects against GBM, but there are no reports regarding its effect on Hsp27 expression in gliomas. The aim of the present study was to asses the effect of resveratrol on Hsp27 expression and apoptosis in non-transfected and transfected U-87 MG human glioblastoma cells. In order to block the Hsp27 expression, siRNA transfection was performed. Non-transfected and transfected cells were treated with either 10 or 15 μM resveratrol. The effects of resveratrol were compared with quercetin, a well-known Hsp27 inhibitor. Resveratrol was found to induce apoptosis more effectively than quercetin. Our data showed that resveratrol induces dose- and time-dependent cell death. We also determined that silencing of Hsp27 with siRNA makes the cells more vulnerable to apoptosis upon resveratrol treatment. The highest effect was observed in the 15 μM resveratrol and 25 nM siRNA combination group (suppressed Hsp27 expression by 93.4% and induced apoptosis by 101.2%). This study is the first report showing that resveratrol reduces Hsp27 levels, and siRNA-mediated Hsp27 silencing enhances the therapeutic effects of resveratrol in glioma cells. Our results suggest that resveratrol administration in combination with Hsp27 silencing has a potential to be used as a candidate for GBM treatment.

Charcot-Marie-Tooth 2F (Hsp27 mutations): A review

Charcot-Marie-Tooth disease is a commonly inherited form of neuropathy. Although named over 100 years ago, identification of subtypes of Charcot-Marie-Tooth has rapidly expanded in the preceding decades with the advancement of genetic sequencing, including type 2F (CMT2F), due to mutations in heat shock protein 27 (Hsp27). However, despite CMT being one of the most common inherited neurological diseases, definitive mechanistic models of pathology and effective treatments for CMT2F are lacking. This review extensively profiles the published literature on CMT2F and distal hereditary motor neuropathy II (dHMN II), a similar neuropathy with exclusively motor symptoms that is also due to mutations in Hsp27. This includes a review of case reports and sequencing studies detailing disease course. Included are tables listing of all known published mutations of Hsp27 that cause symptoms of CMT2F and dHMN II. Furthermore, pathological mechanisms are assessed. While many groups have established pathologies relating to defective chaperone function, cellular neurofilament and microtubule structure and function, and mitochondrial and metabolic dysfunction, there are still discrepancies in results between different model systems. Moreover, initial mouse models have also produced promising results with similar phenotypes to humans, however discrepancies still exist. Both patient-focused and scientific studies have demonstrated variability in phenotypes even considering specific mutations. Given the clinical heterogeneity in presentation, CMT2F and dHMN II likely result from similar pathological mechanisms of the same general disease process that may present distinctly due to other genetic and environment influences. Determining how these influences exert their effects to produce pathology contributing to the disease phenotype will be a major future challenge ahead in the field.

MiR-214 sensitizes human colon cancer cells to 5-FU by targeting Hsp27

Overcoming chemorestistance to 5-fluorouracil (5-FU) could offer a new treatment option for highly malignant colon cancer. In our study, differential microRNA expression profiling revealed that miR-214 is downregulated in 5-FU-resistant colon cancer cells compared to normal cells. In vitro, miR-214 could sensitize non-resistant colon cancer cells and 5-FU-resistant colon cancer cellsto 5-FU. Functionally, miR-214 inhibited cell clone formation and cell growth and enhanced 5-FU-inducing cell apoptosis and caspase-3 levels. MiR-214 targeted heat shock protein 27 (Hsp27), as confirmed via dual luciferase reporter assays and western blots. Hsp27 also sensitized HT-29 and LoVo to 5-FU by enhancing cell apoptosis. Overexpression of Hsp27 could block miR-214 with an effect on the sensitivity of colon cancer cells to 5-FU. In conclusion, miR-214 sensitizes colon cancer cells to 5-FU by targeting Hsp27, indicating a significant role for this miRNA in colon cancer chemotherapy.

Is the small heat shock protein HspB1 (Hsp27) a real and predominant target of methylglyoxal modification?

This study analyzed the interaction of commercial monoclonal anti-methylglyoxal antibodies that predominantly recognize argpyrimidine with unmodified and modified model proteins and small heat shock proteins. These antibodies specifically recognize methylglyoxal (MG)-modified bovine serum albumin and lysozyme, but they react equally well with both unmodified and MG-modified HspB1. Mutation R188W decreased the interaction of these antibodies with unmodified HspB1, thus indicating that this residue participates in the formation of antigenic determinant. However, these antibodies did not recognize either short (ESRAQ) or long (IPVTFESRAQLGGP) peptides with primary structure identical to that at Arg188 of HspB1. Neither of the peptides obtained after the cleavage of HspB1 at Met or Cys residues were recognized by anti-argpyrimidine antibodies. This means that unmodified HspB1 contains a discontinuous epitope that includes the sequence around Arg188 and that this epitope is recognized by anti-argpyrimidine antibodies in unmodified HspB1. Incubation of HspB1 with MG is accompanied by the accumulation of hydroimidazolones, but not argpyrimidines. Therefore, conclusions based on utilization of anti-argpyrimidine antibodies and indicating that HspB1 is the predominant and preferential target of MG modification in the cell require revision.

Role of TLR4-p38 MAPK-Hsp27 signal pathway in LPS-induced pulmonary epithelial hyperpermeability

Background

The breakdown of alveolar barrier dysfunction contributes to Lipopolysaccharide stimulated pulmonary edema and acute lung injury. Actin cytoskeleton has been implicated to be critical in regulation of epithelial barrier. Here, we performed in vivo and in vitro study to investigate role of TLR4-p38 MAPK-Hsp27 signal pathway in LPS-induced ALI.

Methods

For in vivo studies, 6–8-week-old C57 mice were used, Bronchoalveolar lavage Fluid /Blood fluorescent ratio, wet-to-dry lung weight ratio, as well as protein concentrations and neutrophil cell counts in BALF were detected as either directly or indirectly indicators of pulmonary alveolar barrier dysfunction. And hematoxylin and eosin staining was performed to estimate pulmonary injury. The in vitro explorations of transepithelial permeability were achieved through transepithelial electrical resistance measurement and testing of FITC-Dextran transepithelial flux in A549. In addition, cytoskeletal rearrangement was tested through F-actin immunostaining. And SB203580 was used to inhibit p38 MAPK activation, while siRNA was administered to genetically knockdown specific protein.

Results

We showed that LPS triggered activation of p38 MAPK, rearrangement of cytoskeleton which resulted in severe epithelial hyperpermeability and lung edema. A549 pretreated with TLR4 siRNA、p38 MAPK siRNA and its inhibitor SB203580 displayed a lower permeability and fewer stress fibers formation after LPS stimulation, accompanied with lower phosphorylation level of p38 MAPK and Hsp27, which verified the involvement of TLR4-p38 MAPK-Hsp27 in LPS-evoked alveolar epithelial injury. Inhibition of p38 MAPK activity with SB203580 in vivo attenuated pulmonary edema formation and hyperpermeability in response to LPS.

Conclusions

Our study demonstrated that LPS increased alveolar epithelial permeability both in vitro and in vivo and that TLR4- p38 MAPK- Hsp27 signal pathway dependent actin remolding was involved in this process.

Rosmarinic acid and siRNA combined therapy represses Hsp27 (HSPB1) expression and induces apoptosis in human glioma cells

High expression of Hsp27 in glioma cells has been closely associated with tumor cell proliferation and apoptosis inhibition. The aim of the present study was to asses the effects of rosmarinic acid (RA) on Hsp27 expression and apoptosis in non-transfected and transfected human U-87 MG cells. The effect of rosmarinic acid was compared to quercetin, which is known to be a good Hsp27 inhibitor. In order to block the expression of Hsp27 gene (HSPB1), transfection with specific siRNAs was performed. Western blotting technique was used to assess the Hsp27 expression, and caspase-3 colorimetric activity assay was performed to determine apoptosis induction. According to the results, it was found that RA and quercetin effectively silenced Hsp27 and both agents induced apoptosis by activating the caspase-3 pathway. Eighty and 215 μM RA decreased the level of Hsp27 by 28.8 and 46.7% and induced apoptosis by 30 and 54%, respectively. For the first time, we reported that rosmarinic acid has the ability to trigger caspase-3 induced apoptosis in human glioma cells. As a result of siRNA transfection, the Hsp27 gene was silenced by ~ 50% but did not cause a statistically significant change in caspase-3 activation. It was also observed that apoptosis was induced at a higher level as a result of Hsp27 siRNA and subsequent quercetin or RA treatment. siRNA transfection and 215 μM RA treatment suppressed Hsp27 expression level by 90.5% and increased caspase-3 activity by 58%. Herein, we demonstrated that RA administered with siRNA seems to be a potent combination for glioblastoma therapy.

Association between circulating levels of heat-shock protein 27 and aggressive periodontitis

Heat-shock protein (Hsp) 27 is a major intracellular molecular chaperone and controller of intracellular responses to inflammatory signals. In the extracellular space, recombinant Hsp27 has been described to exert anti-inflammatory activities. The aim of this study was to assess the association between circulating levels of Hsp27 and different types of periodontitis. Pro- and anti-inflammatory cytokines and the stress proteins Hsp27 and Hsp60 with proposed anti- and pro-inflammatory properties, respectively, were measured by two-site ELISA in the serum of patients with aggressive periodontitis (AgP, n = 30), chronic periodontitis (CP, n = 29) and periodontally healthy controls (H, n = 28). Furthermore, Hsp27 and Hsp60 levels were also measured longitudinally in 12 AgP patients at 6 time points up to 3 months after treatment. AgP patients had lower levels of Hsp27 compared to CP patients and healthy subjects (adjusted one-way ANOVA, p < 0.001, followed by post hoc Tukey HSD comparisons), while no differences in levels of Hsp60 or cytokines between the three groups were detected. In CP patients and H subjects, the systemic Hsp27 levels correlated with Hsp60 (r = 0.43, p < 0.001; r = 0.59, p < 0.001, respectively) and with pro-inflammatory cytokines TNF-α (r = 0.48, p < 0.001; r = 0.55, p < 0.001, respectively) and IL-6 (r = 0.44, p < 0.01). However, no such correlations were detected in AgP cases. No consistent temporal patterns of changes of Hsp27 concentration were detected across AgP patients following periodontal treatment. This study provides the first evidence that Hsp27 may be differentially expressed and regulated in AgP patients as compared with CP patients and healthy individuals.

Engineering of a Polydisperse Small Heat-Shock Protein Reveals Conserved Motifs of Oligomer Plasticity

Small heat-shock proteins (sHSPs) are molecular chaperones that bind partially and globally unfolded states of their client proteins. Previously, we discovered that the archaeal Hsp16.5, which forms ordered and symmetric 24-subunit oligomers, can be engineered to transition to an ordered and symmetric 48-subunit oligomer by insertion of a peptide from human HspB1 (Hsp27). Here, we uncovered the existence of an array of oligomeric states (30-38 subunits) that can be populated as a consequence of altering the sequence and length of the inserted peptide. Polydisperse Hsp16.5 oligomers displayed higher affinity to a model client protein consistent with a general mechanism for recognition and binding that involves increased access of the hydrophobic N-terminal region. Our findings, which integrate structural and functional analyses from evolutionarily distant sHSPs, support a model wherein the modular architecture of these proteins encodes motifs of oligomer polydispersity, dissociation, and expansion to achieve functional diversity and regulation.

Borealis-1: a randomized, first-line, placebo-controlled, phase II study evaluating apatorsen and chemotherapy for patients with advanced urothelial cancer

Background

Five-year survival of patients with inoperable, advanced urothelial carcinoma treated with the first-line chemotherapy is 5%-15%. We assessed whether the Hsp27 inhibitor apatorsen combined with gemcitabine plus cisplatin (GC) could improve overall survival (OS) in these patients.

Patients and methods

This placebo-controlled, double-blind, phase II trial randomized 183 untreated urothelial carcinoma patients (North America and Europe) to receive GC plus either placebo (N = 62), 600 mg apatorsen (N = 60), or 1000 mg apatorsen (N = 61). In the experimental arm, treatment included loading doses of apatorsen followed by up to six cycles of apatorsen plus GC. Patients receiving at least four cycles could continue apatorsen monotherapy as maintenance until progression or unacceptable toxicity. The primary end point was OS.

Results

OS was not significantly improved in the single or combined 600- or 1000-mg apatorsen arms versus placebo [hazard ratio (HR), 0.86 and 0.90, respectively]. Exploratory study of specific statistical modeling showed a trend for improved survival in patients with baseline poor prognostic features treated with 600 mg apatorsen compared with placebo (HR = 0.72). Landmark analysis of serum Hsp27 (sHsp27) levels showed a trend toward survival benefit for poor-prognosis patients in 600- and 1000-mg apatorsen arms who achieved lower area under the curve sHsp27 levels, compared with the placebo arm (HR = 0.45 and 0.62, respectively). Higher baseline circulating tumor cells (≥5 cells/7.5 ml) was observed in patients with poor prognosis in correlation with poor survival. Treatment-emergent adverse events were manageable and more common in both apatorsen-treatment arms.

Conclusions

Even though apatorsen combined with standard chemotherapy did not demonstrate a survival benefit in the overall study population, patients with poor prognostic features might benefit from this combination. Serum Hsp27 levels may act as a biomarker to predict treatment outcome. Further exploration of apatorsen in poor-risk patients is warranted.

Phosphorylated Hsp27 is mutually exclusive with ATRX loss and the IDH1R132H mutation and may predict better prognosis among glioblastomas without the IDH1 mutation and ATRX loss

Aim

To identify biomarkers for accurate classification of glioma.

Patients and methods

We evaluated the heat shock protein 27 (Hsp27), phosphorylated Hsp27 (p-Hsp27), ATRX and IDH1^R132Hproteins using immunohistochemistry in 421 glioma tissues. The χ² test was used to assess the relationship between molecular alterations and clinico-pathological parameters. Kaplan-Meier survival curves were constructed, and differences were detected by the log-rank test.

Results

We found that Hsp27 and p-Hsp27 were mainly expressed in aggressive astrocytic gliomas. However, neither Hsp27 nor p-Hsp27 expression was related to survival time for any grade of glioma. Interestingly, p-Hsp27 was mutually exclusive with ATRX loss (ATRX⁻) and the IDH1^R132H mutation, except for one case of anaplastic astrocytoma. We classified glioblastomas (GBMs) into three subtypes: ATRX⁻/IDH1^R132H, high p-Hsp27 expression (p-Hsp27⁺) and none of these three markers. ATRX^-/IDH1^R132Hshowed the longest median survival (19.6 months). The prognostic difference between p-Hsp27⁺ and none of these three markers was significant (15.0 vs 13.1 months, P=0.045). Moreover, p-Hsp27⁺ predicted better sensitivity for standard therapy among GBMs without the IDH1 mutation and ATRX loss (26.3 vs 15.5 months, P=0.008).

Conclusion

p-Hsp27 is a novel biomarker of glioma and might have important clinical value for further classification of patients with wild-type IDH1 and normal ATRX expression, for evaluating prognosis and for guidance for adjuvant therapy.

Cellular Hsp27 interacts with classical swine fever virus NS5A protein and negatively regulates viral replication by the NF-κB signaling pathway

Classical swine fever virus (CSFV) nonstructural protein NS5A is a multifunctional protein functioning in regulation of viral genome replication, protein translation and assembly by interaction with viral or host proteins. Here, heat shock protein 27 (Hsp27) has been identified as a novel binding partner of NS5A by using His tag "pull down" coupled with shotgun LC-MS/MS, with interaction of both proteins further confirmed by co-immunoprecipitation and laser confocal assays. In PK-15 cells, silencing of Hsp27 expression by siRNA enhanced CSFV replication, and upregulation of Hsp27 inhibited viral proliferation. Additionally, we have shown that overexpression of Hsp27 increased NF-κB signaling induced by TNFα. Blocking NF-κB signaling in PK-15 cells overexpressing Hsp27 by ammonium pyrrolidinedithiocarbamate (PDTC) eliminated the inhibition of CSFV replication by Hsp27. These findings clearly demonstrate that the inhibition of CSFV replication by Hsp27 is mediated via the NF-κB signaling pathway.