The role of the hsp90-based chaperone system in signal transduction by nuclear receptors and receptors signaling via MAP kinase

Screening and Identification of the Biomarkers Applied for the Evaluation of Acute and Chronic Thermal Tolerance Ability in Largemouth Bass (Micropterus salmoides)

Affected by the continuously rising temperature, thermal stress leads to a delinked growth rate and resistance to stress in cultured largemouth bass (Micropterus salmoides, LMB) in China. Identification of LMB with better thermal resistance will benefit the breeding of new varieties. However, there has been limited reporting on the evaluation to identify LMB with better thermal resistance. LMB consists of the northern LMB (Micropterus salmoides salmoides, NLMB) and the Florida LMB (Micropterus salmoides floridanus, FLMB). Due to their different geographical distributions, it has been suggested that FLMB exhibit better thermal resistance compared to NLMB. In this study, NLMB and FLMB were subjected to thermal stress for 3 h (acute) and 60 d (chronic) at 33 °C, respectively. Subsequently, the variations of 12 candidate biomarkers between NLMB and FLMB were analyzed. Exposure to acute thermal stress significantly increased plasma cortisol, blood glucose, and lactate levels; activities of superoxide dismutase (SOD), glutathione peroxidase (GPX), catalase (CAT), glucose kinase (GK), pyruvate kinase (PK), lactate dehydrogenase (LDH), and glucose 6 phosphatase (G6Pase); and the expressions of hsp70 and hsp90 in both NLMB and FLMB (p < 0.05). Compared to NLMB, FLMB exhibited a lower plasma cortisol level and a higher expression of hsp90 under acute thermal stress (p < 0.05). Exposure to chronic thermal stress significantly increased plasma cortisol and blood glucose levels, as well as activities of GK, PK, LDH, and G6Pase, as well as expressions of hsp70 and hsp90 in both NLMB and FLMB (p < 0.05). Additionally, FLMB showed a lower expression of hsp70 compared to NLMB (p < 0.05). In conclusion, our results showed that LMB with lower plasma cortisol level and higher expression of hsp90 under acute thermal stress, as well as lower expression of hsp70 under chronic thermal stress were suggested to have better thermal resistance. Our study provides valuable information for identifying and breeding LMB varieties with better thermal resistance in the future.

Molecular modelling, docking and network analysis of phytochemicals from Haritaki churna: role of protein cross-talks for their action

Phytochemicals are bioactive agents present in medicinal plants with therapeutic values. Phytochemicals isolated from plants target multiple cellular processes. In the current work, we have used fractionation techniques to identify 13 bioactive polyphenols in ayurvedic medicine Haritaki Churna. Employing the advanced spectroscopic and fractionation, structure of bioactive polyphenols was determined. Blasting the phytochemical structure allow us to identify a total of 469 protein targets from Drug bank and Binding DB. Phytochemicals with their protein targets from Drug bank was used to create a phytochemical-protein network comprising of 394 nodes and 1023 edges. It highlights the extensive cross-talk between protein target corresponding to different phytochemicals. Analysis of protein targets from Binding data bank gives a network comprised of 143 nodes and 275 edges. Taking the data together from Drug bank and binding data, seven most prominent drug targets (HSP90AA1, c-Src kinase, EGFR, Akt1, EGFR, AR, and ESR-α) were found to be target of the phytochemicals. Molecular modelling and docking experiment indicate that phytochemicals are fitting nicely into active site of the target proteins. The binding energy of the phytochemicals were better than the inhibitors of these protein targets. The strength and stability of the protein ligand complexes were further confirmed using molecular dynamic simulation studies. Further, the ADMET profiles of phytochemicals extracted from HCAE suggests that they can be potential drug targets. The phytochemical cross-talk was further proven by choosing c-Src as a model. HCAE down regulated c-Src and its downstream protein targets such as Akt1, cyclin D1 and vimentin. Hence, network analysis followed by molecular docking, molecular dynamics simulation and in-vitro studies clearly highlight the role of protein network and subsequent selection of drug candidate based on network pharmacology.Communicated by Ramaswamy H. Sarma.

High molecular/low acetylated chitosans reduce adhesion of Campylobacter jejuni to host cells by blocking JlpA

Infections caused by Campylobacter spp. are a major cause of severe enteritis worldwide. Multifactorial prevention strategies are necessary to reduce the prevalence of Campylobacter. In particular, antiadhesive strategies with specific inhibitors of early host-pathogen interaction are promising approaches to reduce the bacterial load. An in vitro flow cytometric adhesion assay was established to study the influence of carbohydrates on the adhesion of C. jejuni to Caco-2 cells. Chitosans with a high degree of polymerization and low degree of acetylation were identified as potent antiadhesive compounds, exerting significant reduction of C. jejuni adhesion to Caco-2 cells at non-toxic concentrations. Antiadhesive and also anti-invasive effects were verified by confocal laser scanning microscopy. For target identification, C. jejuni adhesins FlpA and JlpA were expressed in Escherichia coli ArcticExpress, and the influence of chitosan on binding to fibronectin and HSP90α, respectively, was investigated. While no effects on FlpA binding were found, a strong inhibition of JlpA-HSP90α binding was observed. To simulate real-life conditions, chicken meat was inoculated with C. jejuni, treated with antiadhesive chitosan, and the bacterial load was quantified. A strong reduction of C. jejuni load was observed. Atomic force microscopy revealed morphological changes of C. jejuni after 2 h of chitosan treatment, indicating disturbance of the cell wall and sacculi formation by electrostatic interaction of positively charged chitosan with the negatively charged cell surface. In conclusion, our data indicate promising antiadhesive and anti-invasive potential of high molecular weight, strongly de-acetylated chitosans for reducing C. jejuni load in livestock and food production. KEY POINTS: • Antiadhesive effects of chitosan with high DP/low DA against C. jejuni to host cells • Specific targeting of JlpA/Hsp90α interaction by chitosan • Meat treatment with chitosan reduces C. jejuni load.

Single-cell RNA-seq analyses inform necroptosis-associated myeloid lineages influence the immune landscape of pancreas cancer

Introduction

Tumor-infiltrating myeloid cells (TIMs) are key regulators in tumor progression, but the similarity and distinction of their fundamental properties in pancreatic ductal adenocarcinoma (PDAC) remain elusive.

Method

In this study, we conducted scRNA-seq data analysis of cells from 12 primary tumor (PT) tissues, 4 metastatic (Met) tumor tissues, 3 adjacent normal pancreas tissues (Para), and PBMC samples across 16 PDAC patients, and revealed a heterogeneous TIMs environment in PDAC.

Result

Systematic comparisons between tumor and non-tumor samples of myeloid lineages identified 10 necroptosis-associated genes upregulated in PDAC tumors compared to 5 upregulated in paratumor or healthy peripheral blood. A novel RTM (resident tissue macrophages), GLUL-SQSTM1- RTM, was found to act as a positive regulator of immunity. Additionally, HSP90AA1+HSP90AB1+ mast cells exhibited pro-immune characteristics, and JAK3+TLR4+ CD16 monocytes were found to be anti-immune. The findings were validated through clinical outcomes and cytokines analyses. Lastly, intercellular network reconstruction supported the associations between the identified novel clusters, cancer cells, and immune cell populations.

Conclusion

Our analysis comprehensively characterized major myeloid cell lineages and identified three subsets of myeloid-derived cells associated with necroptosis. These findings not only provide a valuable resource for understanding the multi-dimensional characterization of the tumor microenvironment in PDAC but also offer valuable mechanistic insights that can guide the design of effective immuno-oncology treatment strategies.

Effect of Butyl Paraben on Oxidative Stress in the Liver of Mauremys sinensis

Butyl paraben (BuP) has been widely used as a preservative in the cosmetics, food, and medicine industries. Recently, it has become a new pollutant and has attracted much attention. In order to evaluate the toxic effect of BuP on aquatic animals, Chinese striped-neck turtles (Mauremys sinensis) were exposed to BuP solutions with different concentrations of 0, 5, 50, 500, and 5000 µg/L for 20 weeks. The results showed that with an increase in BuP concentration, the activity of antioxidant enzymes (SOD, CAT and GSH-PX) in liver decreased. The expression of key genes in the Nrf2-Keap1 signal pathways first increased and then decreased, while the expression of the HSP70 and HSP90 genes increased. In addition, the liver had an inflammatory reaction. The expression of the BAFF and IL-6 genes increased and then decreased with an increase in BuP concentration, while the expression of P50 and P65 increased significantly. Oxidative stress induced apoptosis, and the expression of pro-apoptosis genes (BAX, cytc, Caspase3 and Caspase9) increased, while the expression of the anti-apoptosis gene Bcl2 decreased. The results provide an important reference for the comprehensive ecological and health risk assessment of environmental BuP.

Promastigote-to-Amastigote Conversion in Leishmania spp.-A Molecular View

A key factor in the successful infection of a mammalian host by Leishmania parasites is their conversion from extracellular motile promastigotes into intracellular amastigotes. We discuss the physical and chemical triggers that induce this conversion and the accompanying changes at the molecular level crucial for the survival of these intracellular parasites. Special emphasis is given to the reliance of these trypanosomatids on the post-transcriptional regulation of gene expression but also to the role played by protein kinases, chaperone proteins and proteolytic enzymes. Lastly, we offer a model to integrate the transduction of different stress signals for the induction of stage conversion.

Heat-induced increases in body temperature in lactating dairy cows: impact on the cumulus and granulosa cell transcriptome of the periovulatory follicle

Cows acutely heat stressed after a pharmacologically induced luteinizing hormone (LH) surge had periovulatory changes in the follicular fluid proteome that may potentiate ovulation and impact oocyte developmental competence. Because the cellular origins of differentially abundant proteins were not known, we have examined the cumulus and granulosa cell transcriptomes from the periovulatory follicle in cows exhibiting varying levels of hyperthermia when occurring after the LH surge. After pharmacological induction of a dominant follicle, lactating dairy cows were administered gonadotropin releasing hormone (GnRH) and maintained in thermoneutral conditions (~67 temperature-humidity index [THI]) or heat stress conditions where THI was steadily increased for ~12 h (71 to 86 THI) and was sufficient to steadily elevate rectal temperatures. Cumulus-oocyte complexes and mural granulosa cells were recovered by transvaginal aspiration of dominant follicle content ~16 h after GnRH. Rectal temperature was used as a continuous, independent variable to identify differentially expressed genes (DEGs) increased or decreased per each 1 °C change in temperature. Cumulus (n = 9 samples) and granulosa (n = 8 samples) cells differentially expressed (false discovery rate [FDR] < 0.05) 25 and 87 genes, respectively. The majority of DEGs were upregulated by hyperthermia. Steady increases in THI are more like the "turning of a dial" than the "flipping of a switch." The moderate but impactful increases in rectal temperature induced modest fold changes in gene expression (<2-fold per 1 °C change in rectal temperature). Identification of cumulus DEGs involved in cell junctions, plasma membrane rafts, and cell-cycle regulation are consistent with marked changes in the interconnectedness and function of cumulus after the LH surge. Depending on the extent to which impacts may be occurring at the junctional level, cumulus changes may have indirect but impactful consequences on the oocyte as it undergoes meiotic maturation. Two granulosa cell DEGs have been reported by others to promote ovulation. Based on what is known, several other DEGs are suggestive of impacts on collagen formation or angiogenesis. Collectively these and other findings provide important insight regarding the extent to which the transcriptomes of the components of the periovulatory follicle (cumulus and mural granulosa cells) are affected by varying degrees of hyperthermia.

Hyperbaric oxygen influences chronic wound healing – a cellular level review

Chronic wound is a serious medical issue due to its high prevalence and complications; hyperbaric oxygen therapy (HBOT) is also considered in comprehensive treatment. Clinical trials, including large meta-analyses bring inconsistent results about HBOT efficacy. This review is summarizing the possible effect of HBOT on the healing of chronic wound models at the cellular level. HBOT undoubtedly escalates the production of reactive oxygen and nitrogen radicals (ROS and RNS), which underlie both the therapeutic and toxic effects of HBOT on certain tissues. HBOT paradoxically elevates the concentration of Hypoxia inducible factor (HIF) 1 by diverting the HIF-1 degradation to pathways that are independent of the oxygen concentration. Elevated HIF-1 stimulates the production of different growth factors, boosting the healing process. HBOT supports synthesis of Heat shock proteins (HSP), which are serving as chaperones of HIF-1. HBOT has antimicrobial effect, increases the effectiveness of some antibiotics, stimulates fibroblasts growth, collagen synthesis and suppresses the activity of proteolytic enzymes like matrix metalloproteinases. All effects of HBOT were investigated on cell cultures and animal models, the limitation of their translation is discussed at the end of this revie

Hsp90 modulates human sperm capacitation via the Erk1/2 and p38 MAPK signaling pathways

BACKGROUND

Heat shock protein 90 (Hsp90) is a highly abundant eukaryotic molecular chaperone that plays important roles in client protein maturation, protein folding and degradation, and signal transduction. Previously, we found that both Hsp90 and its co-chaperone cell division cycle protein 37 (Cdc37) were expressed in human sperm. Hsp90 is known to be involved in human sperm capacitation via unknown underlying mechanism(s). As Cdc37 was a kinase-specific co-chaperone of Hsp90, Hsp90 may regulate human sperm capacitation via other kinases. It has been reported that two major mitogen-activated protein kinases (MAPKs), extracellular signal-regulated kinase 1/2 (Erk1/2) and p38, are expressed in human sperm in the same locations as Hsp90 and Cdc37. Phosphorylated Erk1/2 has been shown to promote sperm hyperactivated motility and acrosome reaction, while phosphorylated p38 inhibits sperm motility. Therefore, in this study we explored whether Hsp90 modulates human sperm capacitation via the Erk1/2 and p38 MAPK signaling pathways.

METHODS

Human sperm was treated with the Hsp90-specific inhibitor 17-allylamino-17-demethoxygeldanamycin (17-AAG) during capacitation. Computer-assisted sperm analyzer (CASA) was used to detect sperm motility and hyperactivation. The sperm acrosome reaction was analyzed by using fluorescein isothiocyanate-conjugated Pisum sativum agglutinin (PSA-FITC) staining. The interactions between Hsp90, Cdc37, Erk1/2 and p38 were assessed using co-immunoprecipitation (Co-IP) experiments. Western blotting analysis was used to evaluate the levels of protein expression and phosphorylation.

RESULTS

Human sperm hyperactivation and acrosome reaction were inhibited by 17-AAG, suggesting that Hsp90 is involved in human sperm capacitation. In addition, Co-IP experiments revealed that 17-AAG reduced the interaction between Hsp90 and Cdc37, leading to the dissociation of Erk1/2 from the Hsp90-Cdc37 protein complex. Western blotting analysis revealed that levels of Erk1/2 and its phosphorylated form were subsequently decreased. Decreasing of Hsp90-Cdc37 complex also affected the interaction between Hsp90 and p38. Nevertheless, p38 dissociated from the Hsp90 protein complex and was activated by autophosphorylation.

CONCLUSIONS

Taken together, our findings indicate that Hsp90 is involved in human sperm hyperactivation and acrosome reaction. In particular, Hsp90 and its co-chaperone Cdc37 form a protein complex with Erk1/2 and p38 to regulate their kinase activity. These results suggest that Hsp90 regulates human sperm capacitation via the Erk1/2 and p38 MAPK signaling pathways.

Plasmodium berghei Hsp90 contains a natural immunogenic I-Ab-restricted antigen common to rodent and human Plasmodium species

Thorough understanding of the role of CD4 T cells in immunity can be greatly assisted by the study of responses to defined specificities. This requires knowledge of Plasmodium-derived immunogenic epitopes, of which only a few have been identified, especially for the mouse C57BL/6 background. We recently developed a TCR transgenic mouse line, termed PbT-II, that produces CD4⁺ T cells specific for an MHC class II (I-A^b)-restricted Plasmodium epitope and is responsive to both sporozoites and blood-stage P. berghei. Here, we identify a peptide within the P. berghei heat shock protein 90 as the cognate epitope recognised by PbT-II cells. We show that C57BL/6 mice infected with P. berghei blood-stage induce an endogenous CD4 T cell response specific for this epitope, indicating cells of similar specificity to PbT-II cells are present in the naïve repertoire. Adoptive transfer of in vitro activated T_H1-, or particularly T_H2-polarised PbT-II cells improved control of P. berghei parasitemia in C57BL/6 mice and drastically reduced the onset of experimental cerebral malaria. Our results identify a versatile, potentially protective MHC-II restricted epitope useful for exploration of CD4 T cell-mediated immunity and vaccination strategies against malaria.

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Identification of a novel MHC-II-restricted epitope in P. berghei Hsp90 that is the cognate antigen of PbT-II CD4+ T cells.

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This epitope is conserved among mouse malaria parasites and in Plasmodium falciparum, which causes human malaria.

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Exposure to liver or blood stage P. berghei infection expands a population of endogenous Hsp90-specific CD4+ T cells.

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Dendritic cell-targeted vaccination generates memory PbT-II cells and endogenous Hsp90-specific CD4+ T cells.

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TH1- and TH2-polarised PbT-II cells reduce P. berghei parasitaemia and mitigate development of experimental cerebral malaria.

Effects of ammonia exposure on antioxidant function, immune response and NF-κB pathway in Chinese Strip-necked Turtle (Mauremys sinensis)

As one of the main toxic substances in aquaculture water, ammonia causes seriously physiological harm to aquatic animals. In order to investigate the effects of ammonia exposure on the antioxidant defense, immune response, and NF-κB signaling pathway in Chinese Strip-necked Turtle (Mauremys sinensis), we designed two experimental groups (control and 6.45 mM ammonia), and sampled at 6 h, 24 h, 48 h, re 24 h (recover 24 h), and re 48 h. The results showed that the blood ammonia (BA) content was significantly increased when the turtles were subjected to ammonia, and the activities of cholinesterase (CHE) and aspartate aminotransferase (AST) in the serum also showed a significant upward trend. The malondialdehyde (MDA) content continuously increased during ammonia exposure, and more than doubled at 48 h compared with the control group. The activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-PX), catalase (CAT) and their corresponding relative mRNA expression levels in the liver during ammonia exposure were obviously increased when compared to the control group, but most decreased to the normal levels at re 48 h. In addition, the relative mRNA and protein expression levels of NF-E2 related factor 2 (Nrf2) showed similar up-regulation patterns to antioxidase during ammonia exposed periods; whereas kelch-like ECH-binding protein 1 (Keap1), as Nrf2 negative regulator, showed opposite patterns. Moreover, the relative mRNA expression levels of heat shock proteins (HSP70, HSP90) significantly elevated upon the exposure of ammonia. Furthermore, ammonia increased the relative mRNA and protein expression levels of p50 and p65 at different exposed times. The reative mRNA expression levels of immune cytokines (BAFF and IL-6) were upregulated during ammonia exposured time, while there was a decline but did not return to normal levels, in the recovery periods. Taken together, these results indicated that antioxidation, immunity, and NF-κB signaling played a certain protective role for Mauremys sinensis under ammonia exposure. Our results will be helpful to understand the mechanism of aquatic toxicology induced by ammonia in turtles.

Heat shock protein HSP90 immunoexpression in equine endometrium during oestrus, dioestrus and anoestrus

Heat shock proteins play a crucial role in cellular development, proliferation, differentiation and apoptosis. Heat shock protein 90 (HSP90) has been localised in the human endometrium, where its immunoexpression changes during the menstrual cycle. Similar studies have not been done for the equid species, so the present study aimed to describe endometrial HSP90 immunoexpression in mare endometrium. Endometrial biopsies were formalin-fixed and paraffin-embedded, and sections were stained with haematoxylin-eosin in preparation for HSP90 immunohistochemistry. Immunostaining and morphometric analyses were performed on the epithelial lining, endometrial glands and connective stroma during oestrus, dioestrus phase and anoestrus period (n = 7 per phase or period). Immunoexpression was localised in the basal region of the epithelial cells lining the lumen. Immunoexpression was greater during oestrus than during either dioestrus or anoestrus. During anoestrus, there was little immunostaining in the endometrium, suggesting that HSP90 is involved in the functional modulation of sex steroid receptors in cyclic mares. Indeed, the function of HSP90 as a chaperone in the folding of proteins, such as steroid receptors, might explain the greater intensity of immunostaining during the oestrus and dioestrus phases, compared the anoestrus period. We conclude that, in the mare, HSP90 plays a role in endometrial function and that further studies are needed to test whether it is important in pathological conditions as endometritis.

Hsp90 interacts with Cdc37, is phosphorylated by PKA/PKC, and regulates Src phosphorylation in human sperm capacitation

BACKGROUND

Heat shock protein 90 (Hsp90) signaling pathways participate in protein phosphorylation during sperm capacitation. However, the underlying mechanism is largely unknown.

OBJECTIVE

The aim of this study was to explore the interaction between Hsp90 and its co-chaperone protein, cell division cycle protein Cdc37 (Cdc37), in human spermatozoa.

MATERIALS AND METHODS

We examined the effects of H-89 (a protein kinase A [PKA] inhibitor) and Go6983 (a protein kinase C [PKC] inhibitor) on the phosphorylation of serine, threonine, and tyrosine residues in Hsp90; the effect of 17-allylamino-17-demethoxygeldanamycin (17-AAG, Hsp90 inhibitor) on Y416-Src phosphorylation; and the effects of 17-AAG and geldanamycin on threonine phosphorylation during human sperm capacitation.

RESULTS

Hsp90 co-localized and interacted with Cdc37. During human sperm capacitation, Hsp90 phosphorylation at serine, threonine, and tyrosine residues was inhibited by H-89 and Go6983. In addition, phosphorylation of residue Y416 in the tyrosine kinase Src (its active site) was inhibited by 17-AAG, and the threonine phosphorylation levels of some proteins were decreased by 17-AAG and geldanamycin.

DISCUSSION AND CONCLUSION

Taken together, our data showed that the interaction of Hsp90 with Cdc37 regulates total protein threonine phosphorylation and Src phosphorylation via its serine, threonine, and tyrosine phosphorylation, which are controlled by PKA and PKC during human sperm capacitation. The results of this study help understand the mechanism underlying Hsp90 regulation of sperm function.

FK506 binding proteins and inflammation related signalling pathways; basic biology, current status and future prospects for pharmacological intervention

FK506 binding (FKBP) proteins are part of the highly conserved immunophilin family and its members have fundamental roles in the regulation of signalling pathways involved in inflammation, adaptive immune responses, cancer and developmental biology. The original member of this family, FKBP12, is a well-known binding partner for the immunosuppressive drugs tacrolimus (FK506) and sirolimus (rapamycin). FKBP12 and its analog, FKBP12.6, function as cis/trans peptidyl prolyl isomerases (PPIase) and they catalyse the interconversion of cis/trans prolyl conformations. Members of this family uniquely contain a PPIase domain, which may not be functional. The larger FKBPs, such as FKBP51, FKBP52 and FKBPL, contain extra regions, including tetratricopeptide repeat (TPR) domains, which are important for their versatile protein-protein interactions with inflammation-related signalling pathways. In this review we focus on the pivotal role of FKBP proteins in regulating glucocorticoid signalling, canonical and non-canonical NF-κB signalling, mTOR/AKT signalling and TGF-β signalling. We examine the mechanism of action of FKBP based immunosuppressive drugs on these cell signalling pathways and how off target interactions lead to the development of side effects often seen in the clinic. Finally, we discuss the latest advances in the role of FKBPs as therapeutic targets and the development of novel agents for a range of indications of unmet clinical need, including glucocorticoid resistance, obesity, stress-induced inflammation and novel cancer immunotherapy.

UV-B radiation bearings on ephemeral soma in the shallow water tunicate Botryllus schlosseri

Sedentary shallow water marine organisms acquire numerous protective mechanisms to mitigate the detrimental effects of UV radiation (UV-R). Here we investigated morphological and gene expression outcomes in colonies of the cosmopolitan ascidian Botryllus schlosseri, up to 15-days post UV-B irradiation. Astogeny in Botryllus is characterized by weekly repeating sets of asexual budding, coinciding with apoptotic elimination of functional zooids (blastogenesis). Ten UV-B doses were administered to three clusters: sublethal, enhanced-mortality, lethal (LD₅₀ = 6.048 kJ/m²) which differed in mortality rates, yet reflected similar distorted morphotypes, and arrested blastogenesis, all intensified in the enhanced-mortality/lethal clusters. Even the sub-lethal doses inflicted expression modifications in 8 stress proteins (HSP 90/70 families and NIMA) as well as morphological blastogenesis. The morphological/gene-expression impacts in surviving colonies lasted for 15 days post irradiation (two blastogenic-cycles), where all damaged and arrested zooids/buds were absorbed, after which the colonies returned to their normal blastogenic-cycles and gene expression profiles, and initiated new buds. The above reflects a novel colonial maintenance strategy associated with the disposable-soma tenet, where the ephemeral soma in Botryllus is eliminated without engaging with the costs of repair, whereas other colonial components, primarily the pool of totipotent stem cells, are sustained under yet unknown colonial-level regulatory cues.

Continuous Inking Affects the Biological and Biochemical Responses of Cuttlefish Sepia pharaonis

Several marine mollusks, including cephalopods (cuttlefish, squid, and octopus) and gastropods (e.g., sea hares), can release a colored ink secretion when chased by predators or stimulated. Ink release is part of a defensive response, but the threshold for the biochemical responses caused by stimulation is unknown. The present study aimed to reveal antipredator responses of cuttlefish, such as escaping via inking and/or jetting, and to investigate its biological and biochemical responses to continuous ink release. Results showed that the behavioral responses to continuous ink release mainly manifested as blazing body pattern changes. Cuttlefish escaped from predators covered by jetting/inking and warned the potential threats by displaying a unique body pattern. Moreover, persistent inking in the presence of an overt stimulus caused uncontrollable ink release from the ink duct/anal canal (loss of control). This study first verified the characteristics of the cuttlefish ink solution, prepared a standard curve of ink solution concentrations, and fitted the relationship function between the release frequency and the released ink weight. Biological statistics indicated that cuttlefish has the ability to continuously release ink (releasing ∼90% of the ink from the ink sac) and that the individuals adapted well during the recovery period. However, re-releasing ink would result in "overexploitation" and high mortality. Hexokinase (HK), pyruvate kinase (PK), and superoxide dismutase (SOD) activities, as well as malondialdehyde (MDA) concentration increased or remained stable in different tissues after releasing ink. The expression of heat shock protein 90 and arginine kinase (AK) were upregulated by stimuli in all tissues. Biochemical changes indicated that continuous inking not only consumed considerable energy but also damaged the tissues. In summary, cuttlefish released almost 90% of their ink for active defense against predators, and it took ∼30 days for the ink sac to be refilled, but "overexploitation" resulted in serious physiological damage. These findings will be helpful to further study the defense and ink release mechanisms and to consider animal health and welfare when using cephalopods as experimental animals and for aquaculture practices.

Partners in Mischief: Functional Networks of Heat Shock Proteins of Plasmodium falciparum and Their Influence on Parasite Virulence

The survival of the human malaria parasite Plasmodium falciparum under the physiologically distinct environments associated with their development in the cold-blooded invertebrate mosquito vectors and the warm-blooded vertebrate human host requires a genome that caters to adaptability. To this end, a robust stress response system coupled to an efficient protein quality control system are essential features of the parasite. Heat shock proteins constitute the main molecular chaperone system of the cell, accounting for approximately two percent of the malaria genome. Some heat shock proteins of parasites constitute a large part (5%) of the 'exportome' (parasite proteins that are exported to the infected host erythrocyte) that modify the host cell, promoting its cyto-adherence. In light of their importance in protein folding and refolding, and thus the survival of the parasite, heat shock proteins of P. falciparum have been a major subject of study. Emerging evidence points to their role not only being cyto-protection of the parasite, as they are also implicated in regulating parasite virulence. In undertaking their roles, heat shock proteins operate in networks that involve not only partners of parasite origin, but also potentially functionally associate with human proteins to facilitate parasite survival and pathogenicity. This review seeks to highlight these interplays and their roles in parasite pathogenicity. We further discuss the prospects of targeting the parasite heat shock protein network towards the developments of alternative antimalarial chemotherapies.

Biological Actions of the Hsp90-binding Immunophilins FKBP51 and FKBP52

Immunophilins are a family of proteins whose signature domain is the peptidylprolyl-isomerase domain. High molecular weight immunophilins are characterized by the additional presence of tetratricopeptide-repeats (TPR) through which they bind to the 90-kDa heat-shock protein (Hsp90), and via this chaperone, immunophilins contribute to the regulation of the biological functions of several client-proteins. Among these Hsp90-binding immunophilins, there are two highly homologous members named FKBP51 and FKBP52 (FK506-binding protein of 51-kDa and 52-kDa, respectively) that were first characterized as components of the Hsp90-based heterocomplex associated to steroid receptors. Afterwards, they emerged as likely contributors to a variety of other hormone-dependent diseases, stress-related pathologies, psychiatric disorders, cancer, and other syndromes characterized by misfolded proteins. The differential biological actions of these immunophilins have been assigned to the structurally similar, but functionally divergent enzymatic domain. Nonetheless, they also require the complementary input of the TPR domain, most likely due to their dependence with the association to Hsp90 as a functional unit. FKBP51 and FKBP52 regulate a variety of biological processes such as steroid receptor action, transcriptional activity, protein conformation, protein trafficking, cell differentiation, apoptosis, cancer progression, telomerase activity, cytoskeleton architecture, etc. In this article we discuss the biology of these events and some mechanistic aspects.

Djhsp90s are crucial regulators during planarian regeneration and tissue homeostasis

Heat shock protein 90 family members (HSP90s), as molecular chaperones, have conserved roles in the physiological processes of eukaryotes regulating cytoprotection, increasing host resistance and so on. However, whether HSP90s affect regeneration in animals is unclear. Planarians are emerging models for studying regeneration in vivo. Here, the roles of three hsp90 genes from planarian Dugesia japonica are investigated by WISH and RNAi. The results show that: (1) Djhsp90s expressions are induced by heat and cold shock, tissue damage and ionic liquid; (2) Djhsp90s mRNA are mainly distributed each side of the body in intact worms as well as blastemas in regenerative worms; (3) the worms show head regression, lysis, the body curling and the regeneration arrest or even failure after Djhsp90s RNAi; (4) Djhsp90s are involved in autophagy and locomotion of the body. The research results suggest that Djhsp90s are not only conserved in cytoprotection, but also involved in homeostasis maintenance and regeneration process by regulating different pathways in planarians.

Structure and Interactions of the TPR Domain of Sgt2 with Yeast Chaperones and Ybr137wp

Small glutamine-rich tetratricopeptide repeat-containing protein 2 (Sgt2) is a multi-module co-chaperone involved in several protein quality control pathways. The TPR domain of Sgt2 and several other proteins, including SGTA, Hop, and CHIP, is a highly conserved motif known to form transient complexes with molecular chaperones such as Hsp70 and Hsp90. In this work, we present the first high resolution crystal structures of Sgt2_TPR alone and in complex with a C-terminal peptide PTVEEVD from heat shock protein, Ssa1. Using nuclear magnetic resonance spectroscopy and isothermal titration calorimetry, we demonstrate that Sgt2_TPR interacts with peptides corresponding to the C-termini of Ssa1, Hsc82, and Ybr137wp with similar binding modes and affinities.

Systematic Proteomic Identification of the Heat Shock Proteins (Hsp) that Interact with Estrogen Receptor Alpha (ERα) and Biochemical Characterization of the ERα-Hsp70 Interaction

Heat shock proteins (Hsps) are known to associate with estrogen receptors (ER) and regulate ER-mediated cell proliferation. Historically, the studies in this area have focused on Hsp90. However, some critical aspects of the Hsp-ERα interactions remain unclear. For example, we do not know which Hsps are the major or minor ERα interactants and whether or not different Hsp isoforms associate equally with ERα. In the present study, through a quantitative proteomic method we found that 21 Hsps and 3 Hsp cochaperones were associated with ERα in human 293T cells that were cultured in a medium containing necessary elements for cell proliferation. Four Hsp70s (Hsp70-1, Hsc70, Grp75, and Grp78) were the most abundant Hsps identified to associate with ERα, followed by two Hsp90s (Hsp90α and Hsp90β) and three Hsp110s (Hsp105, HspA4, and HspA4L). Hsp90α was found to be 2–3 times more abundant than Hsp90β in the ERα-containing complexes. Among the reported Hsp cochaperones, we detected prostaglandin E synthase 3 (p23), peptidyl-prolyl cis-trans isomerase FKBP5 (FKBP51), and E3 ubiquitin-protein ligase CHIP (CHIP). Studies with the two most abundant ERα-associated Hsps, Hsp70-1 and Hsc70, using human breast cancer MCF7 cells demonstrate that the two Hsps interacted with ERα in both the cytoplasm and nucleus when the cells were cultured in a medium supplemented with fetal bovine serum and phenol red. Interestingly, the ERα-Hsp70-1/Hsc70 interactions were detected only in the cytoplasm but not in the nucleus under hormone starvation conditions, and stimulation of the starved cells with 17β-estradiol (E2) did not change this. In addition, E2-treatment weakened the ERα-Hsc70 interaction but had no effect on the ERα-Hsp70-1 interaction. Further studies showed that significant portions of Hsp70-1 and Hsc70 were associated with transcriptionally active chromatin and inactive chromatin, and the two Hsps interacted with ERα in both forms of the chromatins in MCF7 cells.

A novel role for the immunophilin FKBP52 in motor coordination

FKBP52 is a ubiquitously distributed immunophilin that has been associated with wide-ranging functions in cell signalling as well as hormonal and stress responses. Amongst other pathways, it acts via complex-formation with corticosteroid receptors and has consequently been associated with stress- and age- related neurodegenerative disorders including Alzheimer's and Parkinson's diseases. Reduced levels of FKBP52 have been linked to tau dysfunction and amyloid beta toxicity in AD. However, FKBP52's role in cognition and neurodegenerative disorder-like phenotypes remain to be elucidated. The present study aimed therefore at investigating the cognitive and behavioural effects of reduced FKBP52 levels of genetically modified mice during ageing. Female and male FKBP52(+/+), FKBP52(+/-) and FKBP52(-/-) mice were compared at two-, ten-, twelve-, fifteen- and eighteen-months-of-age in a series of behavioural tests covering specie-specific behaviour, motor activity and coordination, fear-, spatial and recognition memory as well as curiosity and emotionality. Whilst cognitively unimpaired, FKBP52(+/-) mice performed worse on an accelerating rotating rod than FKBP52(+/+) littermates across all age-groups suggesting that FKBP52 is involved in processes controlling motor coordination. This deficit did not exacerbate with age but did worsen with repeated testing; pointing towards a role for FKBP52 in learning of tasks requiring motor coordination abilities. This study contributes to the knowledge base of FKBP52's implication in neurodegenerative diseases by demonstrating that FKBP52 by itself does not directly affect cognition and may therefore rather play an indirect, modulatory role in the functional pathology of AD, whereas it directly affects motor coordination, an early sign of neurodegenerative damages to the brain.

The effect of heat stress on bull sperm quality and related HSPs expression

Heat stress dramatically decreases bull sperm quality and has recently received more attention due to the warmer global climate and more intensive production. However, no data exist regarding sperm quality or the related molecular mechanisms under heat stress. Recent studies showed that inducible heat shock proteins (HSPs) play an important role in the dairy heat stress regulation. In this article, to investigate the impacts of heat stress on sperm quality and the associated molecular mechanisms, sperm quality and enzyme activities concerning acrosome reaction were assessed in Simmental, Limousin and Yanbian bulls under heat stress. Subsequently, changes in heat shock protein expression profiles of Simmental bulls were observed, because we observed that sperm quality of these bulls was most sensitive to heat stress. Finally, the relationship between sperm quality and heat shock protein expression under heat stress was analyzed. The results show that summer heat stress decreased the sperm quality of the three bull breeds significantly. Moreover, different levels of heat stimulation induced various enzyme activity changes, among which the activity change in acrosomal enzyme was the most remarkable. Furthermore, the expression of heat shock proteins in the sperm was influenced by the imposed heat stress, among which the expression levels of HSP60 and HSP70 were increased while HSP90 decreased. In summary, our data show that heat stress seriously affects sperm quality and that HSP90 was most sensitive, although it should be noted that seasonal effects may confound these results. This change in heat shock protein expression may be the major factor that affected the sperm quality of the bulls. The findings may provide a new hypothesis for how heat stress impacts reproduction mechanistically.

Dietary antioxidants at supranutritional doses modulate skeletal muscle heat shock protein and inflammatory gene expression in sheep exposed to heat stress

The objective of this study was to investigate the effects of chronic heat (thermal) stress and dietary antioxidant supplementation on the expression of heat shock proteins and inflammatory genes in the skeletal muscle of sheep. Twenty-four Merino × Poll Dorset crossbred ewes were allocated to either a control (10 IU vitamin E and 0.24 mg Se/kg DM) or high-antioxidant (VitE+Se; 100 IU vitamin E and 1.20 mg Se/kg DM) diet and were exposed to 2 thermal (temperature) treatments (thermoneutral [TN]: 18°C-21°C and 26%-30% relative humidity; heat stress [HS]: 28°C-40°C and 40%-50% relative humidity) for 1 wk. Physiological parameters were recorded daily, and muscle biopsies were conducted at the end of thermal treatments. Total RNA was extracted from muscle samples and reverse transcribed to cDNA for real-time PCR analysis. Respiration rates and rectal temperature were increased in response to HS (84.2 vs. 161 breaths per minute and 39.52°C vs. 40.06°C for TN and HS conditions, respectively; P < 0.001). There were interactions between dietary and thermal treatments, indicating that dietary antioxidant supplementation reduced respiration rate (P = 0.097) and rectal temperature (P = 0.086) of sheep during HS but not TN conditions. Skeletal muscle heat shock transcription factor 1 (HSF1) mRNA abundance was increased by HS (1.3-fold; P < 0.050) but was not changed (P = 0.77) by dietary antioxidant supplementation. The expression of skeletal muscle heat shock protein 70 (HSP70) mRNA was increased (P < 0.001) 3.5-fold by HS and tended (P = 0.08) to be increased by dietary antioxidant supplementation. Although there were no main effects of diet (P = 0.42) or HS (P = 0.47) on skeletal muscle HSP90 mRNA expression, there was an interaction (P = 0.040) such that HSP90 mRNA expression was increased (P = 0.010) in antioxidant-supplemented sheep under HS compared to TN conditions. Skeletal muscle nuclear factor kappa B (NF-κB) and tissue necrosis factor α (TNF-α) mRNA abundances were increased by exposure to heat (5.2-fold, P = 0.005 for NF-κB; 5.7-fold, P = 0.013 for TNF-α) ,but there was no main effect (P > 0.05) of dietary antioxidant supplementation. There was, however, an interaction between thermal and dietary treatments such that dietary antioxidant supplementation ameliorated the effect of HS on NF-κB and TNF-α mRNA expression. Taken together, these results indicate that high dietary antioxidants modulate skeletal muscle expression of heat shock proteins, proinflammatory cytokine, and NF-κB transcription, which may protect against HS in sheep.

Hsp transcript induction is correlated with physiological changes under drought stress in Indian mustard

Brassica juncea is an important oilseed crop and drought stress is major abiotic stress that limits its growth and productivity. RH0116 (drought tolerant) and RH8812 (drought sensitive) genotypes were undertaken to study some of the physiological parameters and hsp gene expression related to stress tolerance under drought stress conditions. Differential response in terms of seed germination, electrolyte leakage, RWC, osmotic potential was observed in the selected genotypes. In vitro seed germination studies using PEG stress treatments indicated reduced seed germination with increasing levels of stress treatment. Electrolyte leakage increased, whereas, relative water content and osmotic potential decreased in stressed seedlings. Expression of hsp gene was found to be upregulated during drought stress as the transcripts were present only in the stressed plants and disappeared upon rehydration. The drought tolerant variety showed higher transcript accumulation as compared to the sensitive variety. The study showed that drought induced changes in gene expression in two contrasting genotypes were consistent with the physiological response.

Functional characterization of heat-shock protein 90 from Oryza sativa and crystal structure of its N-terminal domain

Heat-shock protein 90 (Hsp90) is an ATP-dependent molecular chaperone that is essential for the normal functioning of eukaryotic cells. It plays crucial roles in cell signalling, cell-cycle control and in maintaining proteome integrity and protein homeostasis. In plants, Hsp90s are required for normal plant growth and development. Hsp90s are observed to be upregulated in response to various abiotic and biotic stresses and are also involved in immune responses in plants. Although there are several studies elucidating the physiological role of Hsp90s in plants, their molecular mechanism of action is still unclear. In this study, biochemical characterization of an Hsp90 protein from rice (Oryza sativa; OsHsp90) has been performed and the crystal structure of its N-terminal domain (OsHsp90-NTD) was determined. The binding of OsHsp90 to its substrate ATP and the inhibitor 17-AAG was studied by fluorescence spectroscopy. The protein also exhibited a weak ATPase activity. The crystal structure of OsHsp90-NTD was solved in complex with the nonhydrolyzable ATP analogue AMPPCP at 3.1 Å resolution. The domain was crystallized by cross-seeding with crystals of the N-terminal domain of Hsp90 from Dictyostelium discoideum, which shares 70% sequence identity with OsHsp90-NTD. This is the second reported structure of a domain of Hsp90 from a plant source.

Ubiquitylation of nuclear receptors: new linkages and therapeutic implications

The nuclear receptor (NR) superfamily is a group of transcriptional regulators that control multiple aspects of both physiology and pathology and are broadly recognized as viable therapeutic targets. While receptor-modulating drugs have been successful in many cases, the discovery of new drug targets is still an active area of research, because resistance to NR-targeting therapies remains a significant clinical challenge. Many successful targeted therapies have harnessed the control of receptor activity by targeting events within the NR signaling pathway. In this review, we explore the role of NR ubiquitylation and discuss how the expanding roles of ubiquitin could be leveraged to identify additional entry points to control receptor function for future therapeutic development.

Heat shock proteins in multiple myeloma

Heat shock proteins are molecular chaperones with a central role in protein folding and cellular protein homeostasis. They also play major roles in the development of cancer and in recent years have emerged as promising therapeutic targets. In this review, we discuss the known molecular mechanisms of various heat shock protein families and their involvement in cancer and in particular, multiple myeloma. In addition, we address the current progress and challenges in pharmacologically targeting these proteins as anti-cancer therapeutic strategies.

Pim kinases in hematological malignancies: where are we now and where are we going?

The proviral insertion in murine (PIM) lymphoma proteins are a serine/threonine kinase family composed of three isoformes: Pim-1, Pim-2 and Pim-3. They play a critical role in the control of cell proliferation, survival, homing and migration. Recently, overexpression of Pim kinases has been reported in human tumors, mainly in hematologic malignancies. In vitro and in vivo studies have confirmed their oncogenic potential. Indeed, PIM kinases have shown to be involved in tumorgenesis, to enhance tumor growth and to induce chemo-resistance, which is why they have become an attractive therapeutic target for cancer therapy. Novel molecules inhibiting Pim kinases have been evaluated in preclinical studies, demonstrating to be effective and with a favorable toxicity profile. Given the promising results, some of these compounds are currently under investigation in clinical trials. Herein, we provide an overview of the biological activity of PIM-kinases, their role in hematologic malignancies and future therapeutic opportunities.

Two HSPs gene from juvenile Amur sturgeon (Acipenser schrenckii): cloning, characterization and expression pattern to crowding and hypoxia stress

In this study, the cDNA sequences of HSP70 and HSP90 were isolated from the special chondr-ganoid scale, Amur sturgeon, for the first time. Homology analysis indicated that amino acid sequences of HSP70 and HSP90 shared high identity with other species (82.68-99.07 and 90.19-98.07%, respectively). The tissue expression analysis showed that the asHSP70 and asHSP90 mRNA were ubiquitously expressed in all the examined tissues under unstressed condition. The expression pattern of HSP70 and HSP90 under chronic (crowding) and acute (hypoxia) stress was examined by q-PCR in liver, spleen and kidney. Results showed that stocking density could significantly influence the expression of HSP70 at day 20 and/or day 40. In contrast to stocking density, levels of HSP70 transcripts indicated a remarkable increase in all examined tissues after hypoxia stress. HSP90 levels in liver and spleen increased significantly in high stocking density. By comparison, significant increase of asHSP90 in kidney was only found in high stocking density at day 40. Similar to HSP70, the levels of HSP90 transcripts showed significant increases after hypoxia stress except the transcript of liver in H2 group 6 h after hypoxia. The assessment of asHSP70 and asHSP90 mRNA levels under crowding and hypoxia stresses indicated that asHSP70 and asHSP90 gene might be good indicators of stressful situations for Amur sturgeon. Taking serum globulin and electrolytes account, we suggest that crowding and hypoxia stress can result in considerable stress for Amur sturgeon.

Chaperoning G protein-coupled receptors: from cell biology to therapeutics

G protein-coupled receptors (GPCRs) are membrane proteins that traverse the plasma membrane seven times (hence, are also called 7TM receptors). The polytopic structure of GPCRs makes the folding of GPCRs difficult and complex. Indeed, many wild-type GPCRs are not folded optimally, and defects in folding are the most common cause of genetic diseases due to GPCR mutations. Both general and receptor-specific molecular chaperones aid the folding of GPCRs. Chemical chaperones have been shown to be able to correct the misfolding in mutant GPCRs, proving to be important tools for studying the structure-function relationship of GPCRs. However, their potential therapeutic value is very limited. Pharmacological chaperones (pharmacoperones) are potentially important novel therapeutics for treating genetic diseases caused by mutations in GPCR genes that resulted in misfolded mutant proteins. Pharmacoperones also increase cell surface expression of wild-type GPCRs; therefore, they could be used to treat diseases that do not harbor mutations in GPCRs. Recent studies have shown that indeed pharmacoperones work in both experimental animals and patients. High-throughput assays have been developed to identify new pharmacoperones that could be used as therapeutics for a number of endocrine and other genetic diseases.

Hemolymph proteome changes during worker brood development match the biological divergences between western honey bees (Apis mellifera) and eastern honey bees (Apis cerana)

Background

Hemolymph plays key roles in honey bee molecule transport, immune defense, and in monitoring the physiological condition. There is a lack of knowledge regarding how the proteome achieves these biological missions for both the western and eastern honey bees (Apis mellifera and Apis cerana). A time-resolved proteome was compared using two-dimensional electrophoresis-based proteomics to reveal the mechanistic differences by analysis of hemolymph proteome changes between the worker bees of two bee species during the larval to pupal stages.

Results

The brood body weight of Apis mellifera was significantly heavier than that of Apis cerana at each developmental stage. Significantly, different protein expression patterns and metabolic pathways were observed in 74 proteins (166 spots) that were differentially abundant between the two bee species. The function of hemolymph in energy storage, odor communication, and antioxidation is of equal importance for the western and eastern bees, indicated by the enhanced expression of different protein species. However, stronger expression of protein folding, cytoskeletal and developmental proteins, and more highly activated energy producing pathways in western bees suggests that the different bee species have developed unique strategies to match their specific physiology using hemolymph to deliver nutrients and in immune defense.

Conclusions

Our disparate findings constitute a proof-of-concept of molecular details that the ecologically shaped different physiological conditions of different bee species match with the hemolymph proteome during the brood stage. This also provides a starting point for future research on the specific hemolymph proteins or pathways related to the differential phenotypes or physiology.

Electronic supplementary material

The online version of this article (doi:10.1186/1471-2164-15-563) contains supplementary material, which is available to authorized users.

Chloride channelopathies of ClC-2

Chloride channels (ClCs) have gained worldwide interest because of their molecular diversity, widespread distribution in mammalian tissues and organs, and their link to various human diseases. Nine different ClCs have been molecularly identified and functionally characterized in mammals. ClC-2 is one of nine mammalian members of the ClC family. It possesses unique biophysical characteristics, pharmacological properties, and molecular features that distinguish it from other ClC family members. ClC-2 has wide organ/tissue distribution and is ubiquitously expressed. Published studies consistently point to a high degree of conservation of ClC-2 function and regulation across various species from nematodes to humans over vast evolutionary time spans. ClC-2 has been intensively and extensively studied over the past two decades, leading to the accumulation of a plethora of information to advance our understanding of its pathophysiological functions; however, many controversies still exist. It is necessary to analyze the research findings, and integrate different views to have a better understanding of ClC-2. This review focuses on ClC-2 only, providing an analytical overview of the available literature. Nearly every aspect of ClC-2 is discussed in the review: molecular features, biophysical characteristics, pharmacological properties, cellular function, regulation of expression and function, and channelopathies.

Post-translational regulation of endothelial nitric oxide synthase in vascular endothelium

Nitric oxide (NO) is a short-lived gaseous signaling molecule. In blood vessels, it is synthesized in a dynamic fashion by endothelial nitric oxide synthase (eNOS) and influences vascular function via two distinct mechanisms, the activation of soluble guanylyl cyclase (sGC)/cyclic guanosine monophosphate (cGMP)-dependent signaling and the S-nitrosylation of proteins with reactive thiols (S-nitrosylation). The regulation of eNOS activity and NO bioavailability is critical to maintain blood vessel function. The activity of eNOS and ability to generate NO is regulated at the transcriptional, posttranscriptional, and posttranslational levels. Post-translational modifications acutely impact eNOS activity and dysregulation of these mechanisms compromise eNOS activity and foster the development of cardiovascular diseases (CVDs). This review will intergrate past and current literature on the post-translational modifications of eNOS in both health and disease.

Mineralocorticoid receptor phosphorylation regulates ligand binding and renal response to volume depletion and hyperkalemia

Nuclear receptors are transcription factors that regulate diverse cellular processes. In canonical activation, ligand availability is sufficient to produce receptor binding, entraining downstream signaling. The mineralocorticoid receptor (MR) is normally activated by aldosterone, which is produced in both volume depletion and hyperkalemia, states that require different homeostatic responses. We report phosphorylation at S843 in the MR ligand-binding domain that prevents ligand binding and activation. In kidney, MR(S843-P) is found exclusively in intercalated cells of the distal nephron. In volume depletion, angiotensin II and WNK4 signaling decrease MR(S843-P) levels, whereas hyperkalemia increases MR(S843-P). Dephosphorylation of MR(S843-P) results in aldosterone-dependent increases of the intercalated cell apical proton pump and Cl(-)/HCO3(-) exchangers, increasing Cl(-) reabsorption and promoting increased plasma volume while inhibiting K(+) secretion. These findings reveal a mechanism regulating nuclear hormone receptor activity and implicate selective MR activation in intercalated cells in the distinct adaptive responses to volume depletion and hyperkalemia.

Phase I study of BIIB028, a selective heat shock protein 90 inhibitor, in patients with refractory metastatic or locally advanced solid tumors

PURPOSE

Heat shot protein 90 (Hsp90) is a ubiquitous molecular chaperone involved in protein folding, activation, and assembly, including key mediators of signal transduction, cell-cycle control, and transcriptional regulation. We conducted a phase I dose-finding and pharmacokinetic/pharmacodynamic study of BIIB028, a prodrug designed to inhibit Hsp90 activity.

EXPERIMENTAL DESIGN

Patients with advanced solid tumors were enrolled and received escalating doses of BIIB028 intravenously twice a week in 21-day cycles (3+3 design). Response was evaluated after two cycles.

RESULTS

Forty-one patients received doses of 6 to 192 mg/m2. The maximum tolerated dose was 144 mg/m2. Dose-limiting toxicities were syncope (n=1) and fatigue (n=1). Common toxicities at least possibly related to drug were grades 1 to 2, including fatigue (46%), diarrhea (44%), nausea (44%), vomiting (29%), hot flushes (29%), and abnormal dreams (17%). The concentration-time curves for day 1 and day 18 for both prodrug and active metabolite (CF2772) showed a negligible difference. There was a dose-dependent increase in plasma exposure for BIIB028 (CF3647) and CF2772 with plasma half-life of 0.5 and 2.1 hours, respectively. Pharmacodynamic analyses showed significant increases in Hsp70 in peripheral blood mononuclear cells and significantly decreased circulating human EGF receptor-2 extracellular domain in all patients who received BIIB028 at dose levels of 48 mg/m2 or more. Stable disease for at least eight cycles (24 weeks) was achieved in 5 (12%) patients (for durations of 6, 6, 8, 12.5, and 19 months).

CONCLUSION

BIIB028 is a well-tolerated molecule that showed target impact and was associated with prolonged stable disease in two patients.

Estradiol receptors in breast cancer cells: associated co-factors as targets for new therapeutic approaches

Estrogen receptors α (ERα) and β (ERβ) are nuclear receptors which transduce estradiol (E2) response in many tissues including the mammary gland and breast cancers (BC). They activate or inhibit specific genes involved in cell cycle progression and cell survival through multiple enzyme activities leading to malignant transformation. Hormone therapy (antiestrogens (AEs) and aromatase inhibitors (AIs) have been widely used to block the mitogenic action of E2 in patients with ER-positive BC. ERs act in concert with numerous other proteins outside and inside the nucleus where co-activators such as histone modifying enzymes help reaching optimum gene activation. Moreover, E2-mediated gene regulation can occur through ERs located at the plasma membrane or G protein-coupled estrogen receptor (GPER), triggering protein kinase signaling cascades. Classical AEs as well as AIs are inefficient to block the cascades of events emanating from the membrane and from E2 binding to GPER, leading patients to escape anti-hormone treatments and hormone therapy resistance. Many pathways are involved in resistance, mostly resulting from over-expression of growth factor membrane receptors, in particular the HER2/ErbB2 which can be inhibited by specific antibodies or tyrosine kinases inhibitors. Together with the Hsp90 molecular chaperone machinery, a complex interplay between ERs, co-activators, co-repressors and growth factor-activated membrane pathways represents potent targets which warrant to be manipulated alone and in combination to designing novel therapies. The discovery of new potential targets arising from micro array studies gives the opportunity to activate or inhibit different new ER-modulating effectors for innovative therapeutic interventions.

Waon therapy upregulates Hsp90 and leads to angiogenesis through the Akt-endothelial nitric oxide synthase pathway in mouse hindlimb ischemia

BACKGROUND

Thermal therapy, namely Waon therapy, has previously been reported to regulate nitric oxide (NO) and endothelial NO synthase (eNOS) and augment ischemia-induced angiogenesis in mice and improve limb ischemia in patients with peripheral artery disease. The aim of this study was to clarify the precise mechanism by which Waon therapy augments angiogenesis in mice with hindlimb ischemia.

METHODS AND RESULTS

Unilateral hindlimb ischemia was induced in apolipoprotein E-deficient mice and Waon therapy was performed for 5 weeks. Heat shock protein 90 (Hsp90), phosphorylated-Akt, and phosphorylated-eNOS were detected in arterial endothelial cells of ischemic hindlimbs and all were upregulated by Waon therapy compared to controls. Waon therapy also increased serum concentrations of nitrite and nitrate. Capillary density and the ischemic limb/normal side blood perfusion ratio monitored by laser Doppler perfusion imaging in the Waon therapy group were significantly increased beyond those in the control group. The effect of Waon therapy on angiogenesis through the activation of the Hsp90/Akt/eNOS pathway was attenuated by the administration of a Hsp90 inhibitor.

CONCLUSIONS

It is suggested that Waon therapy upregulates Hsp90, which contributes to the activation of the Akt/eNOS/NO pathway, and induces angiogenesis in mice with hindlimb ischemia.

FKBP immunophilins and Alzheimer's disease: a chaperoned affair

The FK506-binding protein (FKBP) family of immunophilins consists of proteins with a variety of protein-protein interaction domains and versatile cellular functions. Analysis of the functions of immunophilins has been the focus of studies in recent years and has led to the identification of various molecular pathways in which FKBPs play an active role. All FKBPs contain a domain with prolyl cis/trans isomerase (PPIase) activity. Binding of the immunosuppressant molecule FK506 to this domain inhibits their PPIase activity while mediating immune suppression through inhibition of calcineurin. The larger members, FKBP51 and FKBP52, interact with Hsp90 and exhibit chaperone activity that is shown to regulate steroid hormone signalling. From these studies it is clear that FKBP proteins are expressed ubiquitously but show relatively high levels of expression in the nervous system. Consistent with this expression, FKBPs have been implicated with both neuroprotection and neurodegeneration. This review will focus on recent studies involving FKBP immunophilins in Alzheimer's-disease-related pathways.