Chaperonins in disease: mechanisms, models, and treatments

The Influence of Chitosan Derivatives in Combination with Bacillus subtilis Bacteria on the Development of Systemic Resistance in Potato Plants with Viral Infection and Drought

Viral diseases of potatoes are among the main problems causing deterioration in the quality of tubers and loss of yield. The growth and development of potato plants largely depend on soil moisture. Prevention strategies require comprehensive protection against pathogens and abiotic stresses, including modeling the beneficial microbiome of agroecosystems combining microorganisms and immunostimulants. Chitosan and its derivatives have great potential for use in agricultural engineering due to their ability to induce plant immune responses. The effect of chitosan conjugate with caffeic acid (ChCA) in combination with Bacillus subtilis 47 on the transcriptional activity of PR protein genes and changes in the proteome of potato plants during potato virus Y (PVY) infection and drought was studied. The mechanisms of increasing the resistance of potato plants to PVY and lack of moisture are associated with the activation of transcription of genes encoding PR proteins: the main protective protein (PR-1), chitinase (PR-3), thaumatin-like protein (PR-5), protease inhibitor (PR-6), peroxidase (PR-9), and ribonuclease (PR-10), as well as qualitative and quantitative changes in the plant proteome. The revealed activation of the expression of marker genes of systemic acquired resistance and induced systemic resistance under the influence of combined treatment with B. subtilis and chitosan conjugate indicate that, in potato plants, the formation of resistance to viral infection in drought conditions proceeds synergistically. By two-dimensional electrophoresis of S. tuberosum leaf proteins followed by MALDI-TOF analysis, 10 proteins were identified, the content and composition of which differed depending on the experiment variant. In infected plants treated with ChCA, the synthesis of proteinaceous RNase P 1 and oxygen-evolving enhancer protein 2 was enhanced in conditions of normal humidity, and 20 kDa chaperonin and TMV resistance protein N-like was enhanced in conditions of lack of moisture. The virus coat proteins were detected, which intensively accumulated in the leaves of plants infected with potato Y-virus. ChCA treatment reduced the content of these proteins in the leaves, and in plants treated with ChCA in combination with Bacillus subtilis, viral proteins were not detected at all, both in conditions of normal humidity and lack of moisture, which suggests the promising use of chitosan derivatives in combination with B. subtilis bacteria in the regulation of plant resistance.

Chaperonin: Co-chaperonin Interactions

Co-chaperonins function together with chaperonins to mediate ATP-dependent protein folding in a variety of cellular compartments. Chaperonins are evolutionarily conserved and form two distinct classes, namely, group I and group II chaperonins. GroEL and its co-chaperonin GroES form part of group I and are the archetypal members of this family of protein folding machines. The unique mechanism used by GroEL and GroES to drive protein folding is embedded in the complex architecture of double-ringed complexes, forming two central chambers that undergo conformational rearrangements that enable protein folding to occur. GroES forms a lid over the chamber and in doing so dislodges bound substrate into the chamber, thereby allowing non-native proteins to fold in isolation. GroES also modulates allosteric transitions of GroEL. Group II chaperonins are functionally similar to group I chaperonins but differ in structure and do not require a co-chaperonin. A significant number of bacteria and eukaryotes house multiple chaperonin and co-chaperonin proteins, many of which have acquired additional intracellular and extracellular biological functions. In some instances, co-chaperonins display contrasting functions to those of chaperonins. Human HSP60 (HSPD) continues to play a key role in the pathogenesis of many human diseases, in particular autoimmune diseases and cancer. A greater understanding of the fascinating roles of both intracellular and extracellular Hsp10 on cellular processes will accelerate the development of techniques to treat diseases associated with the chaperonin family.

Friends in need: How chaperonins recognize and remodel proteins that require folding assistance

Chaperonins are biological nanomachines that help newly translated proteins to fold by rescuing them from kinetically trapped misfolded states. Protein folding assistance by the chaperonin machinery is obligatory in vivo for a subset of proteins in the bacterial proteome. Chaperonins are large oligomeric complexes, with unusual seven fold symmetry (group I) or eight/nine fold symmetry (group II), that form double-ring constructs, enclosing a central cavity that serves as the folding chamber. Dramatic large-scale conformational changes, that take place during ATP-driven cycles, allow chaperonins to bind misfolded proteins, encapsulate them into the expanded cavity and release them back into the cellular environment, regardless of whether they are folded or not. The theory associated with the iterative annealing mechanism, which incorporated the conformational free energy landscape description of protein folding, quantitatively explains most, if not all, the available data. Misfolded conformations are associated with low energy minima in a rugged energy landscape. Random disruptions of these low energy conformations result in higher free energy, less folded, conformations that can stochastically partition into the native state. Two distinct mechanisms of annealing action have been described. Group I chaperonins (GroEL homologues in eubacteria and endosymbiotic organelles), recognize a large number of misfolded proteins non-specifically and operate through highly coordinated cooperative motions. By contrast, the less well understood group II chaperonins (CCT in Eukarya and thermosome/TF55 in Archaea), assist a selected set of substrate proteins. Sequential conformational changes within a CCT ring are observed, perhaps promoting domain-by-domain substrate folding. Chaperonins are implicated in bacterial infection, autoimmune disease, as well as protein aggregation and degradation diseases. Understanding the chaperonin mechanism and the specific proteins they rescue during the cell cycle is important not only for the fundamental aspect of protein folding in the cellular environment, but also for effective therapeutic strategies.

Development of PCR-based markers for the identification and detection of Lophodermella needle cast pathogens on Pinus contorta var. latifolia and P. flexilis

Morphological similarities and fastidious development of increasingly emerging fungal needle pathogens impede accurate disease diagnosis and early detection. This study analyzed the specificity and sensitivity of polymerase chain reaction (PCR)-based markers developed for emerging needle cast pathogens Lophodermella concolor and L. montivaga co-occurring on Pinus contorta var. latifolia, and Bifusella linearis and L. arcuata on P. flexilis. To design primers, we utilized sequences of the internal transcribed spacer (ITS) region and single-copy gene (RH_2175) of the TCP-1/cpn60 chaperonin family searched through genomes of related species. In addition to the DNA of target and non-target fungal species that were used for primer assays, environmental samples with next generation sequencing data were used to evaluate primer sensitivity. Direct amplification using ITS primer pairs generated 248-260 bp amplicons and successfully differentiated the needle pathogens used in this study. Nested amplification of single-copy gene RH_2175 primer pairs which produced 409-527 bp amplicons detected Rhytismataceae species and discriminated both Lophodermella pathogens on P. contorta var. latifolia, respectively. While ITS-based primers had higher sensitivity than the 2175-based primers, both primer sets for L. concolor and L. montivaga detected their respective pathogens in asymptomatic and symptomatic needles. These molecular tools can help monitor and assess needle diseases for forest management and phytosanitary regimes.

Identification, expression analysis and functional verification of two genes encoding small heat shock proteins in the western flower thrips, Frankliniella occidentalis (Pergande)

Small heat shock proteins (sHSPs) help prevent the irreversible aggregation of denatured proteins that occurs in response to organismal stress. In this study, we identified two intron-free genes encoding sHSPs from Frankliniella occidentalis; these were designated FoHSP11.6 and FoHSP28.0 and belonged to an atypical and typical sHSP family, respectively. Both FoHSPs were transcribed in all developmental stages of F. occidentalis with the highest expression levels in pupae and adults and greater expression in males than females. Although the FoHSPs had different temperature-induced expression profiles, they were generally induced by both low and high temperatures and reached maximal expression levels after 0.5-1 h of temperature stress. The FoHSPs expression levels in pupae were induced by drought and high humidity, and higher expression levels were correlated with lower survival rates. The thermotolerance of F. occidentalis decreased when theFoHSPs were silenced by RNA interference. Our results show that FoHSP11.6 and FoHSP28.0 are involved in the response to temperature and drought and may also function in growth and development of F. occidentalis.

The virulence factor GroEL directs the osteogenic and adipogenic differentiation of human periodontal ligament stem cells through the involvement of JNK/MAPK and NF-κB signaling

OBJECTIVE

GroEL, a bacterial metabolite, is an important stimulator of inflammation. The aim of this study is to confirm the effect of the virulence factor GroEL on differentiation potential of periodontal ligament (PDL) stem cells (PDLSCs) and the potential mechanisms.

METHODS

PDLSCs were obtained from extracted human premolars. GroEL was administered to osteogenic- and adipogenic-induced hPDLSCs. Alkaline phosphatase (ALP) staining, Alizarin Red staining and Oil Red staining were performed. Gene and protein expression were separately measured by qPCR and Western blotting. The expression and localization of activated signaling factors were confirmed by immunofluorescence staining. The inhibitors of myeloid differentiation factor 88 (MyD88, an adaptor protein of TLRs), JNK/MAPK and NF-κB signaling were used to verify their specific effects.

RESULTS

First, we found that GroEL inhibited the osteogenic differentiation and enhanced the adipogenic differentiation of hPDLSCs. Next, we found that GroEL increased the expression of TLR2 and TLR4 and GroEL activated JNK/MAPK and NF-κB signaling, which can be blocked by inhibition of MyD88. Finally, we found that inhibition of MyD88 restored GroEL-induced osteogenic and adipogenic differentiation and blocking JNK/MAPK or NF-κB signaling partly restored GroEL effects.

CONCLUSION

In the current study, we revealed a potential interaction between bacteria and host cells by showing that GroEL directs the osteogenic and adipogenic differentiation of hPDLSCs by the involvement of JNK/MAPK and NF-κB signaling. This study provides evidence that bacterial products can influence the differentiation of stem cells and reveals potential effect of GroEL on the context of tissue regeneration.

The virulence factor GroEL promotes gelatinase secretion from cells in the osteoblast lineage: Implication for direct crosstalk between bacteria and adult cells

OBJECTIVE

The aim of this study was to demonstrate the influence of the virulence factor GroEL on osteoblast behavior by characterizing the changes of secreted gelatinases.

DESIGN

ELISA was performed to detect GroEL from samples from patients with or without apical periodontitis. An apical periodontitis model was established in rats and the expression of MMP-2, MMP-9 and NF-κB was evaluated by immunofluorescence staining. The primary osteoblasts and osteoblast-like MC3T3 cells were stimulated with recombinant GroEL, and gelatin zymography was used to determine the activity and expression of MMP-2 and MMP-9. Western blot was used to screen signaling pathways, and immunofluorescence staining was performed to confirm the activated signaling.

RESULTS

First, we found expression of GroEL to be higher in oral saliva, gingival crevicular fluid and periradicular granulation tissue of patients with apical periodontitis than it was in healthy control patients. We next found that recombinant GroEL could increase the activity of the gelatinases, MMP-2 and MMP-9, which were secreted by both primary osteoblasts and MC3T3 cells. In a rat apical periodontitis model, strong expression of gelatinases was confirmed. Then, we found that GroEL-enhanced gelatinase activity was mediated through activation of NF-κB signaling. Acetylated NF-κB accumulated in the cell nucleus and bound to the promoter of MMP-2 and MMP-9 genes, thus initiating their high expression.

CONCLUSION

This study reveals a direct interaction between oral bacteria and adult cells by demonstrating that gelatinase secretion is induced by GroEL, which partially explains bone resorption through gelatinase activation.

Differentially proteomic analysis of the hemocytes against Aeromonas hydrophila infection in oriental river prawn Macrobrachium nipponense by iTRAQ approach

As the direct executors of biological function, the expression level of proteins in host will reveal the molecular mechanisms regulating bacteria infection more directly. In the present study, the differential proteomes of Macrobrachium nipponense hemocytes response to Aeromonas hydrophila infection were identified with isobaric tags for relative and absolute quantitation (iTRAQ) labeling followed by liquid chromatography electrospray ionization tandem mass spectrometry. The hemocyte proteins from the unchallenged and A. hydrophila challenged prawn, M. nipponense, at 12, 24 and 36 h post infection were compared. From this, a total of 3372 proteins were identified and 1014 proteins were considered differentially expressed, of which 117 common differentially expressed proteins were indicated between the time points. Hierarchical clustering, Gene Ontology, Kyoto Encyclopedia of Genes and Genomes enrichment and protein-protein interaction network analyses were performed for the general characterization of overall enriched proteins. Cytoskeletal proteins including myosin heavy chain, myosin regulatory light chain, actin, tubulin alpha/beta chain, troponin I and troponin T as well as antioxidant enzymes such as catalase and cytosolic MnSOD were found significantly up-regulated in hemocytes, indicating that the phagocytosis process and ROS system were induced after challenge with A. hydrophila. And other proteins such as integrin β, innexin inx2-like and heat shock protein 60 also participate in prawn immune response against bacteria. Parallel reaction monitoring analyses were carried out for validation of the expression levels of differentially expressed proteins, which indicated high reliability of the proteomic results. This is the first report on proteome of M. nipponense hemocytes against A. hydrophila infection, which contributes to better understanding on the molecular mechanisms of prawns.

Host-Pathogen Interactions between Xanthomonas fragariae and Its Host Fragaria × ananassa Investigated with a Dual RNA-Seq Analysis

Strawberry is economically important and widely grown, but susceptible to a large variety of phytopathogenic organisms. Among them, Xanthomonas fragariae is a quarantine bacterial pathogen threatening strawberry productions by causing angular leaf spots. Using whole transcriptome sequencing, the gene expression of both plant and bacteria in planta was analyzed at two time points, 12 and 29 days post inoculation, in order to compare the pathogen and host response between the stages of early visible and of well-developed symptoms. Among 28,588 known genes in strawberry and 4046 known genes in X. fragariae expressed at both time points, a total of 361 plant and 144 bacterial genes were significantly differentially expressed, respectively. The identified higher expressed genes in the plants were pathogen-associated molecular pattern receptors and pathogenesis-related thaumatin encoding genes, whereas the more expressed early genes were related to chloroplast metabolism as well as photosynthesis related coding genes. Most X. fragariae genes involved in host interaction, recognition, and pathogenesis were lower expressed at late-phase infection. This study gives a first insight into the interaction of X. fragariae with its host. The strawberry plant changed gene expression in order to consistently adapt its metabolism with the progression of infection.

Circulating heat shock protein 27 as a novel marker of subclinical atherosclerosis in type 2 diabetes: a cross-sectional community-based study

Background

Heat shock protein 27 (HSP27) has been proposed as a vital protective factor in atherosclerosis. The objective of the present study was to evaluate the association between circulating HSP27 and carotid intima–media thickness (IMT) in individuals with type 2 diabetes and to determine whether HSP27 represents an independent marker of subclinical atherosclerosis in this patient population.

Methods

We performed a cross-sectional community-based study in 186 Chinese subjects with a median duration of type 2 diabetes of 8.2 years who underwent ultrasound carotid IMT measurement. Serum HSP27 levels were assessed by ELISA.

Results

Serum HSP27 levels were significantly higher in the IMT (+, > 1.0 mm) group than in the IMT (−, ≤1.0 mm) group, with the median values of 8.80 ng/mL (5.62–12.25) and 6.93 ng/mL (4.23–9.60), respectively (P = 0.006). The discriminative value of HSP27 to evaluate IMT was 7.16 ng/mL and the area under the curve was 0.72 (95%CI = 0.64–0.80, P = 0.0065). Spearman’s rank correlation analysis demonstrated that the concentrations of circulating HSP27 were positively associated with carotid IMT (r = 0.198, P = 0.007) and blood urea nitrogen (r = 0.170, P < 0.05). Furthermore, in the logistic model, serum HSP27 levels were found to be independent predictors for carotid IMT in type 2 diabetic patients after adjustment for onset age of diabetes, blood pressure, total cholesterol and C-reactive protein (OR = 1.085, P = 0.022).

Conclusions

Circulating HSP27, positively correlates with carotid IMT, is an independent predictor for early atherosclerotic changes in diabetes, and may represent a novel marker of subclinical atherosclerosis in type 2 diabetes.

Antibodies to Heat Shock Proteins 90α and 90β in Psoriasis

One of many hypotheses of psoriasis pathogenesis supposes an overexpression of heat shock proteins (Hsps) in different skin layers and systemic immunologic response to them. Hsp90 is one of the most abundant chaperone in eukaryotic cells. The number of studies concerning the role of Hsp90 and anti-Hsp90 antibodies in etiopathogenesis of various diseases is also constantly expanding. Still, there are not many reports concerning potential involvement of this Hsp family or anti-Hsp90 immunization in pathomechanism of psoriasis. The aim of the study was the estimation of anti-Hsp90α and anti-Hsp90β IgG antibodies in the sera of the psoriatic patients at different phases of disease activity in comparison to the sera of healthy individuals. The study material consisted of sera from psoriasis patients (n = 80) in active phase and in the remission phase and healthy individuals (n = 80). Concentrations of anti-Hsp90α and anti-Hsp90β IgG antibodies were determined using ELISA technique. In the patients with psoriasis (both in the active phase of the disease and in the remission phase) concentrations of anti-Hsp90α antibodies were significantly higher than in healthy individuals and they correlated positively with psoriasis area severity index values. The mean concentrations of anti-Hsp90β antibodies in the psoriatic patients and healthy controls were comparable. The obtained results indicate an existence of increased immunological response to Hsp90α in psoriasis. It may suggest the role of the extracellular form of this chaperone and/or anti-Hsp90α antibodies in etiopathogenesis of this dermatosis. The inhibition of Hsp90α may represent a novel therapeutic approach to treat psoriasis.

RapidAIM: a culture- and metaproteomics-based Rapid Assay of Individual Microbiome responses to drugs

BACKGROUND

Human-targeted drugs may exert off-target effects or can be repurposed to modulate the gut microbiota. However, our understanding of such effects is limited due to a lack of rapid and scalable assay to comprehensively assess microbiome responses to drugs. Drugs and other compounds can drastically change the overall abundance, taxonomic composition, and functions of a gut microbiome.

RESULTS

Here, we developed an approach to screen compounds against individual microbiomes in vitro, using metaproteomics to both measure absolute bacterial abundances and to functionally profile the microbiome. Our approach was evaluated by testing 43 compounds (including 4 antibiotics) against 5 individual microbiomes. The method generated technically highly reproducible readouts, including changes of overall microbiome abundance, microbiome composition, and functional pathways. Results show that besides the antibiotics, the compounds berberine and ibuprofen inhibited the accumulation of biomass during in vitro growth of the microbiota. By comparing genus and species level-biomass contributions, selective antibacterial-like activities were found with 35 of the 39 non-antibiotic compounds. Seven of the compounds led to a global alteration of the metaproteome, with apparent compound-specific patterns of functional responses. The taxonomic distributions of altered proteins varied among drugs, i.e., different drugs affect functions of different members of the microbiome. We also showed that bacterial function can shift in response to drugs without a change in the abundance of the bacteria.

CONCLUSIONS

Current drug-microbiome interaction studies largely focus on relative microbiome composition and microbial drug metabolism. In contrast, our workflow enables multiple insights into microbiome absolute abundance and functional responses to drugs. The workflow is robust, reproducible, and quantitative and is scalable for personalized high-throughput drug screening applications.

High Glucose Content Abrogated the Normal Activity of Heat Shock Protein Signaling Pathway in Human Neuroblastoma Cells

BACKGROUND

Detrimental effects of high glucose content (HGC) were proved in different tissues such as the central nervous system. It seems that diabetic conditions could also alter the functional behavior of stem cells residing in the context of the nervous system.

METHODS

The possible effects of 40 and 70 mmol glucose were examined on HSP70 signaling pathways with a specific focus on protein translation, folding values of human neuroblastoma cell line SHSY-5Y after 72 h. Human neuroblastoma cells were exposed to 5, 40 and 70 mmol glucose doses. The transcription level of genes related to HSP70 signaling was also evaluated by PCR array.

RESULTS

The data from PCR array showed high glucose especially 70 mmol could potentially modulate the normal function of protein folding, endoplasmic reticulum derived protein folding and synthesis in neuroblastoma cells (p <0.05).

CONCLUSIONS

Data showed that high glucose condition makes neuroblastoma cells prone to biochemical insufficiency by affecting the function of HSP70 signaling pathway and protein synthesis.

Identification of key sites controlling protein functional motions by using elastic network model combined with internal coordinates

The elastic network model (ENM) is an effective method to extract the intrinsic dynamical properties encoded in protein tertiary structures. We have proposed a new ENM-based analysis method to reveal the motion modes directly responsible for a specific protein function, in which an internal coordinate related to the specific function was introduced to construct the internal/Cartesian hybrid coordinate space. In the present work, the function-related internal coordinates combined with a linear perturbation method were applied to identify the key sites controlling specific protein functional motions. The change in the fluctuations of the internal coordinate in response to residue perturbation was calculated in the hybrid coordinate space by using the linear response theory. The residues with the large fluctuation changes were identified to be the key sites that allosterically control the specific protein function. Two proteins, i.e., human DNA polymerase β and the chaperonin from Methanococcus maripaludis, were investigated as case studies, in which several collective and local internal coordinates were applied to identify the functionally key residues of these two studied proteins. The calculation results are consistent with the experimental observations. It is found that different collective internal coordinates lead to similar results, where the predicted functionally key sites are located at similar positions in the protein structure. While for the local internal coordinates, the predicted key sites tend to be situated at the region near to the coordinate-involving residues. Our studies provide a starting point for further exploring other function-related internal coordinates for other interesting proteins.

Effects of Bacillus aryabhattai TBRC8450 on vibriosis resistance and immune enhancement in Pacific white shrimp, Litopenaeus vannamei

The use of probiotics in aquaculture is a practical alternative to promote animal health and disease prevention. Meanwhile, this practice can also reduce the use of prophylactic antibiotics. The purpose of this study was to identify candidate probiotics that could control pathogen populations in host's gastrointestinal (GI) tract and stimulate host immunity in shrimp aquaculture. Bacillus aryabhattai TBRC8450, a bacterial strain isolated from the environment in a shrimp farm, has an antimicrobial activity against many pathogenic strains of Vibrio harveyi and V. parahaemolyticus. Supplementation of B. aryabhattai to Pacific white shrimp (Litopenaeus vannamei) not only decreased the abundance of Vibrio populations, but also shifted the bacterial community in the shrimp GI tract. We found that supplementation of B. aryabhattai triggered shrimp innate immunity and antioxidant activities. mRNA expression of genes encoding microbial peptides and antioxidant enzymes, including C-type lectin, penaeidin-3, heat shock protein 60, thioredoxin, and ferritin, was significantly upregulated in the hepatopancreas of shrimp fed B. aryabhattai. Furthermore, phenoloxidase activity in the hemocytes and the total antioxidant activity in the plasma were increased, indicating enhanced immune and antioxidant responses at the systemic level. In contrast, supplementation of B. aryabhattai had no effect on the total hemocyte count and superoxide dismutase activity in the plasma and hepatopancreas. Importantly, a pathogen challenge test using V. harveyi 1562 showed a significant increase in survival rates of shrimp fed B. aryabhattai compared to the control group. Our findings suggest that B. aryabhattai TBRC8450 can likely be used as a probiotic to reduce the population of V. harveyi in the shrimp GI tract and to enhance shrimp innate immunity and antioxidant capacity for vibriosis resistance in shrimp aquaculture.

A Review of the Potential Effect of Electroacupuncture and Moxibustion on Cell Repair and Survival: The Role of Heat Shock Proteins

In recent years, a considerable amount of research has been focused on the underlying mechanisms of electroacupuncture and moxibustion assisted tissue repair. Intracellular protein denaturation is a significant pathological step of acute conditions such as stroke, myocardial infarction and acute pancreatitis. Protein aggregation can be observed after the protein denaturation step in chronic diseases of the central nervous system like Alzheimer's and Parkinson's disease, and also in other chronic system diseases including cataract formation. Heat shock proteins (HSPs) are fundamental for intracellular protein repair and work by preventing protein aggregation and assisting denaturated proteins to refold. Further, HSPs can also function for extracellular cell signalling. The focus of this review is to analyse the data studying electroacupuncture and moxibustion induced HSPs, and how acupuncture can survive cells from apoptosis under stress.

Role of the heat shock protein family in bone metabolism

Heat shock proteins (HSPs) are a family of proteins produced by cells in response to exposure to stressful conditions. In addition to their role as chaperones, they also play an important role in the cardiovascular, immune, and other systems. Normal bone tissue is maintained by bone metabolism, particularly by the balance between osteoblasts and osteoclasts, which are physiologically regulated by multiple hormones and cytokines. In recent years, studies have reported the vital role of HSPs in bone metabolism. However, the conclusions remain largely controversial, and the exact mechanisms are still unclear, so a review and analyses of previous studies are of importance. This article reviews the current understanding of the roles and effects of HSPs on bone cells (osteoblasts, osteoclasts, and osteocytes), in relation to bone metabolism.

Beyond proteostasis: Roles of type I chaperonins in bacterial pathogenesis

Nearly all bacterial species express two or more chaperonin genes. Recent data indicate that type I chaperonins may be key players in bacterial infections. This is partly due to the well-known contribution of chaperonins in cellular proteostasis, the latter being compromised during bacterial host infection. In addition to their protein-folding activity, it has been revealed that certain chaperonins also exhibit moonlighting functions that can contribute in different ways to bacterial pathogenicity. Examples range from inducing adhesion molecules in Chlamydophila pneumoniae to supporting intracellular survival in Mycobacterium tuberculosis and Leishmania donovani, to inducing cytokines in Helicobacter pylori to promoting antimicrobial resistance in Escherichia coli, amongst others. This article provides a thorough reviews of our current understanding of the different mechanisms involving type I chaperonins during bacteria-host interactions, and suggests new areas to be explored and the potential of finding new targets for fighting bacterial infections.

Molecular characteristics of a novel HSP60 gene and its differential expression in Manila clams (Ruditapes philippinarum) under thermal and hypotonic stress

The Manila clam Ruditapes philippinarum inhabits the intertidal zone and must therefore tolerate broad fluctuations in water temperature and salinity. Heat shock protein 60 (HSP60) is an evolutionarily conserved, multi-functional protein that plays a significant role in protecting organisms from harmful stress conditions. We cloned the R. philippinarum HSP60 (RpHSP60) gene and analyzed its transcriptional responses to thermal and low-salinity stresses. The complete sequence of RpHSP60 cDNA was 1777 nucleotides, containing a 1728-bp open reading frame encoding a polypeptide of 576-amino acids, with a calculated molecular mass of 61.25 kDa and predicted isoelectric point of 5.08. Comparisons of amino acid sequences and three-dimensional structures of HSP60 revealed that RpHSP60 was highly conserved in the signature HSP60-family domains. RpHSP60 mRNA was detected in all the tested tissues of R. philippinarum, with the highest expression levels in hemocytes. We measured RpHSP60 mRNA levels in the gills under thermal and low-salinity stresses using quantitative real-time reverse transcription-polymerase chain reaction. Following the thermal challenge, RpHSP60 mRNA was significantly upregulated at 6 h, and then progressively downregulated under high-temperature stress (30 °C), while only slight fluctuations were observed under low-temperature stress (-1 °C). Under low-salinity (17 ppt) stress, RpHSP60 mRNA levels were significantly increased at 3, 72, and 96 h (P < 0.05). These results suggest that HSP60 of R. philippinarum may play important roles in responding to high-temperature and low-salinity stresses.

Heat Shock Proteins and Diabetes

Diabetes is a chronic disease, and its prevalence continues to rise and can increase the risk for the progression of microvascular (such as nephropathy, retinopathy and neuropathy) and also macrovascular complications. Diabetes is a condition in which the oxidative stress and inflammation rise. Heat shock proteins (HSPs) are a highly conserved family of proteins that are expressed by all cells exposed to environmental stress, and they have diverse functions. In patients with diabetes, the expression and levels of HSPs decrease, but these chaperones can aid in improving some complications of diabetes, such as oxidative stress and inflammation. (The suppression of some HSPs is associated with a generalized increase in tissue inflammation.) In this review, we summarize the current understanding of HSPs in diabetes as well as their complications, and we also highlight their potential role as therapeutic targets in diabetes.

Protein-Protein Interface and Disease: Perspective from Biomolecular Networks

Protein-protein interactions are involved in many important biological processes and molecular mechanisms of disease association. Structural studies of interfacial residues in protein complexes provide information on protein-protein interactions. Characterizing protein-protein interfaces, including binding sites and allosteric changes, thus pose an imminent challenge. With special focus on protein complexes, approaches based on network theory are proposed to meet this challenge. In this review we pay attention to protein-protein interfaces from the perspective of biomolecular networks and their roles in disease. We first describe the different roles of protein complexes in disease through several structural aspects of interfaces. We then discuss some recent advances in predicting hot spots and communication pathway analysis in terms of amino acid networks. Finally, we highlight possible future aspects of this area with respect to both methodology development and applications for disease treatment.

Neonatal Death and Heart Failure in Mouse with Transgenic HSP60 Expression

Mitochondrial heat shock proteins, such as HSP60, are chaperones responsible for the folding, transport, and quality control of mitochondrial matrix proteins and are essential for maintaining life. Both prosurvival and proapoptotic roles have been proposed for HSP60, and HSP60 is reportedly involved in the initiation of autoimmune, metabolic, and cardiovascular diseases. The role of HSP60 in pathogenesis of these diseases remains unclear, partly because of the lack of mouse models expressing HSP60. In this study we generated HSP60 conditional transgenic mice suitable for investigating in vivo outcomes by expressing HSP60 at the targeted organ in disease models. Ubiquitous HSP60 induction in the embryonic stage caused neonatal death in mice at postnatal day 1. A high incidence of atrial septal defects was observed in HSP60-expressing mice, with increased apoptosis and myocyte degeneration that possibly contributed to massive hemorrhage and sponge-like cardiac muscles. Our results showed that neonatal heart failure through HSP60 induction likely involves developmental defects and excessive apoptosis. The conditional HSP60 mouse model is useful for studying crucial biological questions concerning HSP60.

Expression of Heat Shock Protein 27 in Benign Prostatic Hyperplasia with Chronic Inflammation

Background

Heat shock protein 27 (HSP 27) is known as a mediator in immune response and has been recently found to be expressed in prostate cancer. This study aimed to investigate the role of HSP27 in inflammatory BPH.

Material/Methods

Hospitalized BPH patients who received TURP were divided into 4 groups by the presence and degrees of chronic inflammation: non-inflammatory BPH (NI BPH), mild-inflammatory BPH (MI BPH), moderate-inflammatory BPH (MOI BPH), and severe-inflammatory BPH (SI BPH). Expressions of HSP 27, TNF-α, IL-6, and CD3 in prostate tissues and serum of patients were detected by immunohistochemistry and ELISA.

Results

Expression of HSP27 in BPH with histological inflammation was significantly higher than in non-inflammatory BPH. In inflammatory BPH groups, HSP27 expression gradually increased along with increasing inflammation. There was a significant correlation between the expression of TNF-α, IL-6, CD3 and HSP27 among different inflammatory BPH groups.

Conclusions

HSP27 expression level is associated with the degree of chronic inflammation in BPH and may participate in the pathological process in inflammatory BPH.

Proteomics profiling of chikungunya-infected Aedes albopictus C6/36 cells reveal important mosquito cell factors in virus replication

Chikungunya virus (CHIKV) is the only causative agent of CHIKV fever with persistent arthralgia, and in some cases may lead to neurological complications which can be highly fatal, therefore it poses severe health issues in many parts of the world. CHIKV transmission can be mediated via the Aedes albopictus mosquito; however, very little is currently known about the involvement of mosquito cellular factors during CHIKV-infection within the mosquito cells. Unravelling the neglected aspects of mosquito proteome changes in CHIKV-infected mosquito cells may increase our understanding on the differences in the host factors between arthropod and mammalian cells for successful replication of CHIKV. In this study, the CHIKV-infected C6/36 cells with differential cellular proteins expression were profiled using two-dimensional gel electrophoresis (2DE) coupled with the use of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). 2DE analysis on CHIKV-infected C6/36 cells has shown 23 mosquito cellular proteins that are differentially regulated, and which are involved diverse biological pathways, such as protein folding and metabolic processes. Among those identified mosquito proteins, spermatogenesis-associated factor, enolase phosphatase e-1 and chaperonin-60kD have been found to regulate CHIKV infection. Furthermore, siRNA-mediated gene knockdown of these proteins has demonstrated the biological importance of these host proteins that mediate CHIKV infection. These findings have provided an insight to the importance of mosquito host factors in the replication of CHIKV, thus providing a potential channel for developing novel antiviral strategies against CHIKV transmission.

Chikungunya virus (CHIKV), a re-emerging mosquito-borne virus, is the main cause of CHIKV fever, persistent arthralgia and serious neurological complications which can be highly fatal; therefore, it poses serious health threats worldwide. Unraveling the underappreciated aspects of mosquito cellular factors that contribute to the replication processes of CHIKV was performed using two-dimensional gel electrophoresis (2DE) coupled with the use of matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). The 2DE proteomics profiling of CHIKV-infected mosquito C6/36 cells has revealed twenty-three proteins that were differentially regulated upon CHIKV infection. These proteins are shown to be involved in diverse biological pathways and cellular processes. Notably, upon selected genes knockdown, spermatogenesis-associated factor, enolase phosphatase e-1 and chaperonin-60kD are found to be important during the replication processes of CHIKV. This study illustrates the importance of mosquito cellular factors in association with CHIKV infection in mosquito cells and reveals an interesting portal for developing novel antiviral strategies in CHIKV studies.

Chaperonin-co-chaperonin interactions

Co-chaperonins function together with chaperonins to mediate ATP-dependant protein folding in a variety of cellular compartments. GroEL and its co-chaperonin GroES are the only essential chaperones in Escherichia coli and are the archetypal members of this family of protein folding machines. The unique mechanism used by GroEL and GroES to drive protein folding is embedded in the complex architecture of double-ringed complexes, forming two central chambers that undergo structural rearrangements as part of the folding mechanism. GroES forms a lid over the chamber, and in doing so dislodges bound substrate into the chamber, thereby allowing non-native proteins to fold in isolation. GroES also modulates allosteric transitions of GroEL. A significant number of bacteria and eukaryotes house multiple chaperonin and co-chaperonin proteins, many of which have acquired additional intracellular and extracellular biological functions. In some instances co-chaperonins display contrasting functions to those of chaperonins. Human Hsp60 continues to play a key role in the pathogenesis of many human diseases, in particular autoimmune diseases and cancer. A greater understanding of the fascinating roles of both intracellular and extracellular Hsp10, in addition to its role as a co-chaperonin, on cellular processes will accelerate the development of techniques to treat diseases associated with the chaperonin family.

Heat shock proteins and cardiovascular disease

Atherosclerosis is the leading global cause of mortality, morbidity, and disability. Heat shock proteins (HSPs) are a highly conserved family of proteins with diverse functions expressed by all cells exposed to environmental stress. Studies have reported that several HSPs may be potential risk markers of atherosclerosis and related cardiovascular diseases, or may be directly involved in the atherogenic process itself. HSPs are expressed by cells in atherosclerotic plaque and anti-HSP has been reported to be increased in patients with vascular disease. Autoimmune responses may be generated against antigens present within the atherosclerotic plaque, including HSP and may lead to a cycle of ongoing vascular injury. It has been suggested that by inducing a state of tolerance to these antigens, the atherogenic process may be limited and thus provide a potential therapeutic approach. It has been suggested that anti-HSPs are independent predictors of risk of vascular disease. In this review, we summarize the current understanding of HSP in cardiovascular disease and highlight their potential role as diagnostic agents and therapeutic targets.

Recurrent miscarriages, innate immunity, and autoimmune reaction to chlamydial 60-kDa heat shock protein--is there an association?

OBJECTIVE

To evaluate a potential association of immunity to the Chlamydia trachomatis 60kDa heat shock protein (ChlamHSP60) and recurrent miscarriages.

DESIGN

Prospective study.

SETTING

Outpatient miscarriage clinic of a university-based hospital.

PATIENT(S)

120 asymptomatic women with a history of recurrent miscarriages.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Determination of serum immunoglobulin G (IgG) antibodies (Ab) to ChlamHSP60 and human HSP60 and, in parallel, mannose-binding lectin (MBL) and the total hemolytic complement (CH50); medical history and clinical examination, including multiple relevant laboratory determinants.

RESULT(S)

ChlamHSP60 Ab were detected in 24 (20%) of 120 patients. Antibodies to human HSP60 were found in 19 (15.8%) of 120 patients, and more frequently in individuals who tested positive for ChlamHSP60. ChlamHSP60 were statistically significantly associated with antichlamydial IgG Ab. However, antibodies to ChlamHSP60 were not related to medical history, the number of abortions, or the time frame of fetal loss. ChlamHSP60 antibodies were not associated with the relevant variables of the coagulation cascade, a panel of autoimmune parameters including thyroid autoimmunity, deficiencies of the complement system (low MBL), or with antibodies to common infectious diseases. No statistically significant differences were was found when comparing the prevalence of ChlamHSP60 Ab in the study group with recurrent miscarriages and 90 controls (women attending for an annual pelvic examination).

CONCLUSION(S)

Immunity to ChlamHSP60 does not play a major role in the etiology of recurrent miscarriages.

A novel insecticidal GroEL protein from Xenorhabdus nematophila confers insect resistance in tobacco

Xenorhabdus nematophila is an entomopathogenic bacteria. It secretes a GroEL homolog, XnGroEL protein, toxic to its larval prey. GroEL belongs to the family of molecular chaperones and is required for proper folding of cellular proteins. Oral ingestion of insecticidal XnGroEL protein is toxic to Helicoverpa armigera, leading to cessation of growth and development of the larvae. In the present study, the insecticidal efficacy of XnGroEL against H. armigera has been evaluated in transgenic tobacco plant expressing the protein. A 1.7-kb gene encoding the 58-kDa XnGroEL protein was incorporated into the tobacco genome via Agrobacterium-mediated transformation. The stable integration of the transgene was confirmed by Southern blot analysis and its expression by RT-PCR and western blot analyses in transgenic plants. The transgenic lines showed healthy growth and were phenotypically normal. Insect bioassays revealed significant reduction of 100 % in the survival of larvae (p < 0.001) and 55-77 % reduction in plant damage (p < 0.05 and p < 0.001) compared to the untransformed and vector control plants. The results demonstrate that XnGroEL is a novel potential candidate for imparting insect resistance against H. armigera in plants.

Epitopes of microbial and human heat shock protein 60 and their recognition in myalgic encephalomyelitis

Myalgic encephalomyelitis (ME, also called Chronic Fatigue Syndrome), a common disease with chronic fatigability, cognitive dysfunction and myalgia of unknown etiology, often starts with an infection. The chaperonin human heat shock protein 60 (HSP60) occurs in mitochondria and in bacteria, is highly conserved, antigenic and a major autoantigen. The anti-HSP60 humoral (IgG and IgM) immune response was studied in 69 ME patients and 76 blood donors (BD) (the Training set) with recombinant human and E coli HSP60, and 136 30-mer overlapping and targeted peptides from HSP60 of humans, Chlamydia, Mycoplasma and 26 other species in a multiplex suspension array. Peptides from HSP60 helix I had a chaperonin-like activity, but these and other HSP60 peptides also bound IgG and IgM with an ME preference, theoretically indicating a competition between HSP60 function and antibody binding. A HSP60-based panel of 25 antigens was selected. When evaluated with 61 other ME and 399 non-ME samples (331 BD, 20 Multiple Sclerosis and 48 Systemic Lupus Erythematosus patients), a peptide from Chlamydia pneumoniae HSP60 detected IgM in 15 of 61 (24%) of ME, and in 1 of 399 non-ME at a high cutoff (p<0.0001). IgM to specific cross-reactive epitopes of human and microbial HSP60 occurs in a subset of ME, compatible with infection-induced autoimmunity.

Characterization and expression of SpHsp60 in hemocytes after challenge to bacterial, osmotic and thermal stress from the mud crab Scylla paramamosain

Hsp60 play a crucial role in the process of pathogenic and protective immune responses and is implicated in autoimmune disease. In order to understand the environmental response and immune response of this gene, we cloned a Hsp60 (SpHsp60) gene from the mud crab Scylla paramamosain, localized SpHsp60 in hemocytes by in situ hybridization, and detected the expression of SpHsp60 after stresses in relation to three housekeeping genes (β-actin, 18S rRNA and GAPDH). The full-length of the SpHsp60 cDNA was found to be 2424 bp. The predicted ORF encoded a protein of 576 amino acids with a predicted molecular mass of 61.19 kDa and a theoretical isoelectric point (pI) of 5.46. It shared high scoring identity 95% with the swimming crab Portunus trituberculatus. In situ hybridization assay showed that a higher expression occurred in the granular and semigranular cells when compared to the hyaline hemocytes. It suggested that SpHsp60 was mainly contributed from the granular and semigranular cells in hemolymph. The expression level of SpHsp60 in hemocytes showed a clear time-dependent pattern during the 96 h after stimulated by Vibrio alginolyticus. During this experiment the gene was induced and the highest expression level was observed at 3 h. The significantly up-regulated expression and rapid response of SpHsp60 indicated that the crabs were sensitive to bacterial challenge. After osmotic stress, the expression of SpHsp60 in hemocytes showed that this gene was induced by the high salinity (30‰) and the crabs had its adaptive responses to high salinity, when compared to the normal salinity (15‰). SpHsp60 mRNA expression in hemocytes was analyzed after thermal stress at 6 h, the highest and the lowest expression levels of SpHsp60 were observed at 36 and 32 °C, respectively. This study demonstrated that SpHsp60 was easily induced at the higher temperatures. Based on our research, SpHsp60 participate in innate immune and environmental response of S. paramamosain. It could be used as a biomarker to test the stress caused by the local aquaculture environment.

Sequencing and de novo assembly of the western tarnished plant bug (Lygus hesperus) transcriptome

Background

Mirid plant bugs (Hemiptera: Miridae) are economically important insect pests of many crops worldwide. The western tarnished plant bug Lygus hesperus Knight is a pest of cotton, alfalfa, fruit and vegetable crops, and potentially of several emerging biofuel and natural product feedstocks in the western US. However, little is known about the underlying molecular genetics, biochemistry, or physiology of L. hesperus, including their ability to survive extreme environmental conditions.

Methodology/Principal Findings

We used 454 pyrosequencing of a normalized adult cDNA library and de novo assembly to obtain an adult L. hesperus transcriptome consisting of 1,429,818 transcriptomic reads representing 36,131 transcript isoforms (isotigs) that correspond to 19,742 genes. A search of the transcriptome against deposited L. hesperus protein sequences revealed that 86 out of 87 were represented. Comparison with the non-redundant database indicated that 54% of the transcriptome exhibited similarity (e-value ≤1⁻⁵) with known proteins. In addition, Gene Ontology (GO) terms, Kyoto Encyclopedia of Genes and Genomes (KEGG) annotations, and potential Pfam domains were assigned to each transcript isoform. To gain insight into the molecular basis of the L. hesperus thermal stress response we used transcriptomic sequences to identify 52 potential heat shock protein (Hsp) homologs. A subset of these transcripts was sequence verified and their expression response to thermal stress monitored by semi-quantitative PCR. Potential homologs of Hsp70, Hsp40, and 2 small Hsps were found to be upregulated in the heat-challenged adults, suggesting a role in thermotolerance.

Conclusions/Significance

The L. hesperus transcriptome advances the underlying molecular understanding of this arthropod pest by significantly increasing the number of known genes, and provides the basis for further exploration and understanding of the fundamental mechanisms of abiotic stress responses.

An insecticidal protein from Xenorhabdus ehlersii triggers prophenoloxidase activation and hemocyte decrease in Galleria mellonella

The bacteria Xenorhabdus spp. are entomopathogenic symbionts that can produce several toxic proteins that interfere the immune system of insects. We purified an insecticidal protein from Xenorhabdus ehlersii, and designated it as XeGroEL with an estimated molecular mass of ~58 kDa. Galleria mellonella larva injected with XeGroEL presented prophenoloxidase activation and hemocyte decrease. XeGroEL can kill G. mellonella larva in 48 h with an LD(50) of 0.76 ± 0.08 μg/larva. Our results demonstrate that X. ehlersii possesses a toxic XeGroEL protein acting as a potential factor to activate proPO in host insect, which also provides a meaningful hypothesis to understand the interaction between nematode-symbiotic bacteria and host.

Mycobacterium tuberculosis employs Cpn60.2 as an adhesin that binds CD43 on the macrophage surface

CD43 is a large sialylated glycoprotein found on the surface of haematopoietic cells and has been previously shown to be necessary for efficient macrophage binding and immunological responsiveness to Mycobacterium tuberculosis. Using capsular material from M. tuberculosis and recombinant CD43-Fc, we have employed affinity chromatography to show that Cpn60.2 (Hsp65, GroEL), and to a lesser extent DnaK (Hsp70), bind to CD43. Competitive inhibition using recombinant protein and polyclonal F(ab')(2) antibody-mediated epitope masking studies were used to evaluate M. tuberculosis binding to CD43(+/+) versus CD43(-/-) macrophages. Results showed that Cpn60.2, but not DnaK, acts as a CD43-dependent mycobacterial adhesin for macrophage binding. Assessment of the specific binding between Cpn60.2 and CD43 showed it to be saturable, with a comparatively weak affinity in the low micromolar range. We have also shown that the ability of Cpn60.2 to competitively inhibit M. tuberculosis binding to macrophages is shared by the Escherichia coli homologue, GroEL, but not by the mouse and human Hsp60 homologues. These findings add to a growing field of research that implicates molecular chaperones as having extracellular functions, including bacterial adherence to host cells. Thus, CD43 may act as a Pattern Recognition Receptor (PRR) for bacterial homologues of the 60 kDa molecular chaperone.

Differential expression of LvHSP60 in shrimp in response to environmental stress

Previous studies showed that heat-shock protein 60 (HSP60) was known to function as a molecular chaperone and is an important factor in the innate immune system in mammals. However, little was known about the physiological relevance of HSP60 in marine invertebrates. This study focuses on long-term monitoring of the differential expression of LvHSP60 in shrimp Litopenaeus vannamei in response to environmental stress. The thermal aggregation assay elucidated that LvHSP60 was an effective chaperone. It also suggested that LvHSP60 may employ the cell's intrinsic mechanism to start the immunizing process. Using quantitative real-time PCR to monitor gene expression showed that LvHSP60 was variable under different stresses including environmental stress and pathogenic infection. LvHSP60 was speculated to regulate the adaptive responses to overcome environmental stresses. In conclusion, our study proved that LvHSP60 plays an important role in the intrinsic immune system and stress responses of shrimp.

The francisella tularensis proteome and its recognition by antibodies

Francisella tularensis is the causative agent of a spectrum of diseases collectively known as tularemia. The extreme virulence of the pathogen in humans, combined with the low infectious dose and the ease of dissemination by aerosol have led to concerns about its abuse as a bioweapon. Until recently, nothing was known about the virulence mechanisms and even now, there is still a relatively poor understanding of pathogen virulence. Completion of increasing numbers of Francisella genome sequences, combined with comparative genomics and proteomics studies, are contributing to the knowledge in this area. Tularemia may be treated with antibiotics, but there is currently no licensed vaccine. An attenuated strain, the Live Vaccine Strain (LVS) has been used to vaccinate military and at risk laboratory personnel, but safety concerns mean that it is unlikely to be licensed by the FDA for general use. Little is known about the protective immunity induced by vaccination with LVS, in humans or animal models. Immunoproteomics studies with sera from infected humans or vaccinated mouse strains, are being used in gel-based or proteome microarray approaches to give insight into the humoral immune response. In addition, these data have the potential to be exploited in the identification of new diagnostic or protective antigens, the design of next generation live vaccine strains, and the development of subunit vaccines. Herein, we briefly review the current knowledge from Francisella comparative proteomics studies and then focus upon the findings from immunoproteomics approaches.

Heat-shock proteins in cardiovascular disease

Heat-shock proteins (HSPs) belong to a group of highly conserved families of proteins expressed by all cells and organisms and their expression may be constitutive or inducible. They are generally considered as protective molecules against different types of stress and have numerous intracellular functions. Secretion or release of HSPs has also been described, and potential roles for extracellular HSPs reported. HSP expression is modulated by different stimuli involved in all steps of atherogenesis including oxidative stress, proteolytic aggression, or inflammation. Also, antibodies to HSPs may be used to monitor the response to different types of stress able to induce changes in HSP levels. In the present review, we will focus on the potential implication of HSPs in atherogenesis and discuss the limitations to the use of HSPs and anti-HSPs as biomarkers of atherothrombosis. HSPs could also be considered as potential therapeutic targets to reinforce vascular defenses and delay or avoid clinical complications associated with atherothrombosis.

Listeria monocytogenes uses Listeria adhesion protein (LAP) to promote bacterial transepithelial translocation and induces expression of LAP receptor Hsp60

Listeria monocytogenes interaction with the intestinal epithelium is a key step in the infection process. We demonstrated that Listeria adhesion protein (LAP) promotes adhesion to intestinal epithelial cells and facilitates extraintestinal dissemination in vivo. The LAP receptor is a stress response protein, Hsp60, but the precise role for the LAP-Hsp60 interaction during Listeria infection is unknown. Here we investigated the influence of physiological stressors and Listeria infection on host Hsp60 expression and LAP-mediated bacterial adhesion, invasion, and transepithelial translocation in an enterocyte-like Caco-2 cell model. Stressors such as heat (41°C), tumor necrosis factor alpha (TNF-α) (100 U), and L. monocytogenes infection (10(4) to 10(6) CFU/ml) significantly (P < 0.05) increased plasma membrane and intracellular Hsp60 levels in Caco-2 cells and consequently enhanced LAP-mediated L. monocytogenes adhesion but not invasion of Caco-2 cells. In transepithelial translocation experiments, the wild type (WT) exhibited 2.7-fold more translocation through Caco-2 monolayers than a lap mutant, suggesting that LAP is involved in transepithelial translocation, potentially via a paracellular route. Short hairpin RNA (shRNA) suppression of Hsp60 in Caco-2 cells reduced WT adhesion and translocation 4.5- and 3-fold, respectively, while adhesion remained unchanged for the lap mutant. Conversely, overexpression of Hsp60 in Caco-2 cells enhanced WT adhesion and transepithelial translocation, but not those of the lap mutant. Furthermore, initial infection with a low dosage (10(6) CFU/ml) of L. monocytogenes increased plasma membrane and intracellular expression of Hsp60 significantly, which rendered Caco-2 cells more susceptible to subsequent LAP-mediated adhesion and translocation. These data provide insight into the role of LAP as a virulence factor during intestinal epithelial infection and pose new questions regarding the dynamics between the host stress response and pathogen infection.

GroEL and lipopolysaccharide from Francisella tularensis live vaccine strain synergistically activate human macrophages

Francisella tularensis, the causative agent of tularemia, interacts with host cells of innate immunity in an atypical manner. For most Gram-negative bacteria, the release of lipopolysaccharide (LPS) from their outer membranes stimulates an inflammatory response. When LPS from the attenuated live vaccine strain (LVS) or the highly virulent Schu S4 strain of F. tularensis was incubated with human umbilical vein endothelial cells, neither species of LPS induced expression of the adhesion molecule E-selectin or secretion of the chemokine CCL2. Moreover, a high concentration (10 microg/ml) of LVS or Schu S4 LPS was required to stimulate production of CCL2 by human monocyte-derived macrophages (huMDM). A screen for alternative proinflammatory factors of F. tularensis LVS identified the heat shock protein GroEL as a potential candidate. Recombinant LVS GroEL at a concentration of 10 microg/ml elicited secretion of CXCL8 and CCL2 by huMDM through a TLR4-dependent mechanism. When 1 microg of LVS GroEL/ml was added to an equivalent amount of LVS LPS, the two components synergistically activated the huMDM to produce CXCL8. Schu S4 GroEL was less stimulatory than LVS GroEL and showed a lesser degree of synergy when combined with Schu S4 LPS. These findings suggest that the intrinsically low proinflammatory activity of F. tularensis LPS may be increased in the infected human host through interactions with other components of the bacterium.

Expression of HSP60 and HSP70 in white shrimp, Litopenaeus vannamei in response to bacterial challenge

In the present study, cDNA encoding a heat shock protein 60 (LvHSP60) gene in Litopenaeus vannamei was cloned using a combination of homology and rapid amplification of cDNA end (RACE) methods. The full length of the LvHSP60 cDNA was found to be 2379bp, with a 1737bp open reading frame. The translated amino acid sequence consisted of 579 residues with a calculated molecular mass of 60.8kD and an isoelectronic point (pI) of 5.97. Comparison of the deduced amino acid sequence showed that it has high identity (85-89%) with HSP60/chaperonins from insects and mammals. Quantitative real-time PCR and Western blot analysis were carried out to investigate the expression patterns and distribution profiles of LvHSP60 before and after stimulation with the Gram-positive bacterium Staphylococcus aureus and the Gram-negative bacterium Vibrio alginolyticus. LvHSP60 mRNA was found to be both constitutive and inducible, and was highly expressed in haemocytes and almost all tissues examined, including muscle, stomach, heart, hepatopancreas and gill tissue, but it was less strongly expressed in the intestine. The expression analysis revealed that LvHSP60 was significantly up-regulated in the gills, hepatopancreas and haemocytes after bacterial challenge. Transcription of LvHSP70 was also induced in haemocytes and the hepatopancreas after different bacteria injection. Subsequent flow cytometry analysis showed that the concentration of Ca(2+) ions increased significantly within bacteria-challenged haemocytes by 1.5h after injection. The results indicate that LvHSP60 and LvHSP70 may play important roles in mediating the immune responses of L. vannamei to bacterial challenge, and that the Ca(2+) signalling transduction pathway may be involved in the initiation of the shrimp's immune responses in early stages of infection.

The innate immune and systemic response in honey bees to a bacterial pathogen, Paenibacillus larvae

Background

There is a major paradox in our understanding of honey bee immunity: the high population density in a bee colony implies a high rate of disease transmission among individuals, yet bees are predicted to express only two-thirds as many immunity genes as solitary insects, e.g., mosquito or fruit fly. This suggests that the immune response in bees is subdued in favor of social immunity, yet some specific immune factors are up-regulated in response to infection. To explore the response to infection more broadly, we employ mass spectrometry-based proteomics in a quantitative analysis of honey bee larvae infected with the bacterium Paenibacillus larvae. Newly-eclosed bee larvae, in the second stage of their life cycle, are susceptible to this infection, but become progressively more resistant with age. We used this host-pathogen system to probe not only the role of the immune system in responding to a highly evolved infection, but also what other mechanisms might be employed in response to infection.

Results

Using quantitative proteomics, we compared the hemolymph (insect blood) of five-day old healthy and infected honey bee larvae and found a strong up-regulation of some metabolic enzymes and chaperones, while royal jelly (food) and energy storage proteins were down-regulated. We also observed increased levels of the immune factors prophenoloxidase (proPO), lysozyme and the antimicrobial peptide hymenoptaecin. Furthermore, mass spectrometry evidence suggests that healthy larvae have significant levels of catalytically inactive proPO in the hemolymph that is proteolytically activated upon infection. Phenoloxidase (PO) enzyme activity was undetectable in one or two-day-old larvae and increased dramatically thereafter, paralleling very closely the age-related ability of larvae to resist infection.

Conclusion

We propose a model for the host response to infection where energy stores and metabolic enzymes are regulated in concert with direct defensive measures, such as the massive enhancement of PO activity.

Increased circulating heat shock protein 60 induced by menopause, stimulates apoptosis of osteoblast-lineage cells via up-regulation of toll-like receptors

Postmenopausal osteoporosis is a heterogeneous disorder characterized by accelerated bone loss after natural or surgical menopause and an increased risk of fractures. The bone loss in estrogen deficiency results from the increased bone resorption and impaired ability of osteoblastic bone formation. Previous studies have reported that the HSP60 stimulates osteoclast formation and bone resorption. Here we found that plasma HSP60 levels were significantly higher in postmenopausal (median 1152.4 ng/ml; range 724.7-2123.4 ng/ml) than in premenopausal (median 316.3 ng/ml; range 164.6-638.4 ng/ml) women. In primary human bone marrow stromal cells (hBMSC) and the HS-5 hBMSC cell line, HSP60 significantly reduced cell viability and increased caspase-dependent apoptosis. Consistent with these observations, HSP60 activated caspase-3 and -9, but not caspase-8 in HS-5 cells, and increased the release of mitochondrial cytochrome c into the cytosol. In addition, HSP60 activated p38 and NFkappaB, but not ERK or JNK; importantly, inhibitors of p38 (SB203580) and NFkappaB (PDTC) abolished HSP60-induced apoptosis. Furthermore, Western blotting showed that HSP60 up-regulated TLR-2 and TLR-4 expression, and pretreatment with blocking antibodies for TLR-2 and TLR-4 almost completely eliminated the effects of HSP60 on apoptosis, caspase-3 and -9 activation, and activation of NFkappaB and p38 MAPK. Most notably, ovariectomy-induced bone loss was attenuated in TLR-2 KO mice. In conclusion, up-regulation of TLR-2 by HSP60 may play a critical role in promoting bone loss in the estrogen-deficient state.

Candidate autoantigens identified by mass spectrometry in early rheumatoid arthritis are chaperones and citrullinated glycolytic enzymes

Introduction

The aim of our study was to identify new early rheumatoid arthritis (RA) autoantibodies.

Methods

Sera obtained from 110 early untreated RA patients (<6 months) were analyzed by western blot using HL-60 cell extract, separated on one-dimensional and two-dimensional gel electrophoresis (1-DE, 2-DE). Sera from 50 healthy blood donors and 20 patients with non-RA rheumatisms were used as controls for 1-DE and 2-DE, respectively. The immunoreactive proteins were identified by MALDI-TOF mass spectrometric analysis and the presence of potential sites of citrullination in each of these proteins was evaluated. FT-ICR mass spectrometry was used to verify experimentally the effect of citrullination upon the mass profile observed by MALDI-TOF analysis.

Results

The 110 1-DE patterns allowed detection of 10 recurrent immunoreactive bands of 33, 39, 43, 46, 51, 54, 58, 62, 67 and 70 kDa, which were further characterized by 2-DE and proteomic analysis. Six proteins were already described RA antigens: heterogeneous nuclear ribonucleoprotein A2/B1, aldolase, α-enolase, calreticulin, 60 kDa heat shock protein (HSP60) and BiP. Phosphoglycerate kinase 1 (PGK1), stress-induced phosphoprotein 1 and the far upstream element-binding proteins (FUSE-BP) 1 and 2 were identified as new antigens. Post-translational protein modifications were analyzed and potentially deiminated peptides were found on aldolase, α-enolase, PGK1, calreticulin, HSP60 and the FUSE-BPs. We compared the reactivity of RA sera with citrullinated and noncitrullinated α-enolase and FUSE-BP linear peptides, and showed that antigenicity of the FUSE-BP peptide was highly dependent on citrullination. Interestingly, the anti-cyclic citrullinated peptide antibody (anti-CCP2) status in RA serum at inclusion was not correlated to the reactivity directed against FUSE-BP citrullinated peptide.

Conclusions

Two categories of antigens, enzymes of the glycolytic family and molecular chaperones are also targeted by the early untreated RA autoantibody response. For some of them, and notably the FUSE-BPs, citrullination is involved in the immunological tolerance breakdown observed earlier in RA patients. Autoantibodies recognizing a citrullinated peptide from FUSE-BP may enhance the sensibility for RA of the currently available anti-CCP2 test.

An insecticidal GroEL protein with chitin binding activity from Xenorhabdus nematophila

Xenorhabdus nematophila secretes insecticidal proteins to kill its larval prey. We have isolated an approximately 58-kDa GroEL homolog, secreted in the culture medium through outer membrane vesicles. The protein was orally insecticidal to the major crop pest Helicoverpa armigera with an LC50 of approximately 3.6 microg/g diet. For optimal insecticidal activity all three domains of the protein, apical, intermediate, and equatorial, were necessary. The apical domain alone was able to bind to the larval gut membranes and manifest low level insecticidal activity. At equimolar concentrations, the apical domain contained approximately one-third and the apical-intermediate domain approximately one-half bioactivity of that of the full-length protein. Interaction of the protein with the larval gut membrane was specifically inhibited by N-acetylglucosamine and chito-oligosaccharides. Treatment of the larval gut membranes with chitinase abolished protein binding. Based on the three-dimensional structural model, mutational analysis demonstrated that surface-exposed residues Thr-347 and Ser-356 in the apical domain were crucial for both binding to the gut epithelium and insecticidal activity. Double mutant T347A,S356A was 80% less toxic (p < 0.001) than the wild type protein. The GroEL homolog showed alpha-chitin binding activity with Kd approximately 0.64 microm and Bmax approximately 4.68 micromol/g chitin. The variation in chitin binding activity of the mutant proteins was in good agreement with membrane binding characteristics and insecticidal activity. The less toxic double mutant XnGroEL showed an approximately 8-fold increase of Kd in chitin binding assay. Our results demonstrate that X. nematophila secretes an insecticidal GroEL protein with chitin binding activity.