In search of the molecular mechanism by which small stress proteins counteract apoptosis during cellular differentiation

Modulation of miR-146b Expression during Aging and the Impact of Physical Activity on Its Expression and Chondrogenic Progenitors

The finding of molecules associated with aging is important for the prevention of chronic degenerative diseases and for longevity strategies. MicroRNAs (miRNAs) are post-transcriptional regulators involved in many biological processes and miR-146b-5p has been shown to be involved in different degenerative diseases. However, miR-146b-5p modulation has not been evaluated in mesenchymal stem cells (MSCs) commitment or during aging. Therefore, the modulation of miR-146b-5p in the commitment and differentiation of mesenchymal cells as well as during maturation and aging in zebrafish model were analyzed. In addition, circulating miR-146b-5p was evaluated in human subjects at different age ranges. Thus, the role of physical activity in the modulation of miR-146b-5p was also investigated. To achieve these aims, RT (real-time)-PCR, Western blot, cell transfections, and three-dimensional (3D) culture techniques were applied. Our findings show that miR-146b-5p expression drives MSCs to adipogenic differentiation and increases during zebrafish maturation and aging. In addition, miR-146b-5p expression is higher in females compared to males and it is associated with the aging in humans. Interestingly, we also observed that the physical activity of walking downregulates circulating miR-146b-5p levels in human females and increases the number of chondroprogenitors. In conclusion, miR-146b-5p can be considered an age-related marker and can represent a useful marker for identifying strategies, such as physical activity, aimed at counteracting the degenerative processes of aging.

Genetic studies of heat stress regulation in goat during hot climatic condition

Various direct and indirect environmental constraints have an impact on livestock performance. The physiological parameters, such as rectal temperature, heart rate, and respiratory rate, are the primary indicators of thermal stress. Under a stressed environment temperature humidity index (THI) had established as a vital measurement to identify the thermal stress in livestock. THI in association with climatic variations can define the environmental effect as stressful or comfortable for livestock. Goats are small ruminants that adapt to a wide range of ecological variations due to their anatomical and physiological characteristics. However, the productivity of animals declines at the individual level during thermal stress. Stress tolerance can be determined through genetic studies associated with at the cellular level using physiological as well as molecular approaches. Information on genetic association with thermal stress in goats is scanty, this severely affects their survival and hence productivity of livestock. The ever-increasing demand for food across the globe needs deciphering novel molecular markers as well as stress indicators that play a vital role in livestock improvement. This review represents an analysis of current knowledge of phenotypic differences during thermal stress and signifies the importance of physiological responses and their association at the cellular level in goats. The regulation of vital genes associated with thermal stress such as Aquaporins (AQP 0, 1, 2, 4, 5, 6, 8), aquaglyceroporins (AQP3, 7, 9, and 10) and super-aquaporins (AQP 11, 12); BAX inhibitors such as PERK (PKR like ER kinase), IRE 1(inositol-requiring-1); Redox regulating genes such as NOX; Transport of Na+ and K+ such as ATPase (ATP1A1) and several heat shock proteins have been implicated in heat-stress related adaptations have been elucidated. As these changes have a significant impact on production performance as well as on livestock productivity. Such efforts may help in the development of molecular markers and will assist the breeders to develop heat-tolerant goats with improved productivity.

HAX1-dependent control of mitochondrial proteostasis governs neutrophil granulocyte differentiation

The relevance of molecular mechanisms governing mitochondrial proteostasis to the differentiation and function of hematopoietic and immune cells is largely elusive. Through dissection of the network of proteins related to HCLS1-associated protein X-1, we defined a potentially novel functional CLPB/HAX1/(PRKD2)/HSP27 axis with critical importance for the differentiation of neutrophil granulocytes and, thus, elucidated molecular and metabolic mechanisms underlying congenital neutropenia in patients with HAX1 deficiency as well as bi- and monoallelic mutations in CLPB. As shown by stable isotope labeling by amino acids in cell culture (SILAC) proteomics, CLPB and HAX1 control the balance of mitochondrial protein synthesis and persistence crucial for proper mitochondrial function. Impaired mitochondrial protein dynamics are associated with decreased abundance of the serine-threonine kinase PRKD2 and HSP27 phosphorylated on serines 78 and 82. Cellular defects in HAX1^–/– cells can be functionally reconstituted by HSP27. Thus, mitochondrial proteostasis emerges as a critical molecular and metabolic mechanism governing the differentiation and function of neutrophil granulocytes.

Concentrations of HSP27 and αβ-crystallin in Oula Tibetan sheep meat and their relationship with meat quality during postmortem aging

HSP27 and αβ-crystallin are molecular chaperones participating in multiple cellular processes. Their roles in the development of postmortem meat quality remain unclear. The current study was designed to investigate the relationship between the concentrations of HSP27 and αβ-crystallin with meat quality during postmortem aging. Specifically, cooking loss, color, pH, and the myofibril fragmentation index (MFI) of Oula Tibetan sheep meat were determined, and changes in the concentrations of HSP27 and αβ-crystallin were evaluated. The results indicated that HSP27 concentration significantly decreased in 0-3 days (p < 0.05), presenting a positive correlation with pH (p < 0.05) and a negative correlation with L*, b*, cooking loss, and MFI (p < 0.05, p < 0.05, p < 0.01, p < 0.01). Besides, αβ-crystallin concentration significantly decreased in 0-2 days (p < 0.05), exhibiting a significant positive correlation with pH (p < 0.05) and a negative correlation with L*, b*, cooking loss, and MFI (p < 0.01, p < 0.01, p < 0.01, p < 0.01). The results suggested that the HSP27 and αβ-crystallin may participate in the development of meat quality in Oula Tibetan sheep during postmortem early aging. PRACTICAL APPLICATION: Tenderness, color, and water holding capacity (WHC) are crucial quality attributes of meat. The relationship between the concentrations of HSP27 and αβ-crystallin and meat quality reveals that HSP27 and αβ-crystallin may contribute to the development of meat quality in Oula Tibetan sheep during postmortem aging. Therefore, HSP27 and αβ-crystallin are effective research objects for regulating meat quality during postmortem aging.

In Vitro Anti-Viral Effects of Small Heat Shock Proteins 20 and 27: A Novel Therapeutic Approach

BACKGROUND

The protective effects of heat shock proteins (Hsps) were studied in some infectious and non-infectious diseases, but their specificity was slightly known in various disorders. Among Hsps, small Hsps (e.g. Hsp27 and Hsp20) have important roles in protein folding and translocation, and also in immunity.

METHODS

In this study, overexpression of Hsp20 and Hsp27 was performed by transfection of the plasmids encoding Hsp20 and Hsp27 (pEGFP-Hsp20 and pEGFP-Hsp27) into Huh7.5, Hela and Vero cells using Lipofectamine along with heat shock. Then, their anti-herpes simplex virus-1 (HSV-1), anti- human immunodeficiency virus-1 (HIV-1) and anti-hepatitis C virus (HCV) effects, as well as cytotoxicity, were evaluated in vitro, for the first time.

RESULTS

Our data showed that simultaneous treatment with Lipofectamine and heat shock augmented the rate of transfection and subsequently the expression of Hsps in these cells. Moreover, overexpression of Hsp20 in HCV-infected Huh7.5 cells, HIV-infected Hela cells and HSV-infected Vero cells reduced the replication of HCV, HIV and HSV, respectively. In contrast, overexpression of Hsp27 significantly decreased HSV replication similar to Hsp20, but it did not affect the replication of HIV and HCV.

CONCLUSION

Generally, Hsp20 was identified as a novel anti-HCV, anti-HSV and anti-HIV agent, but Hsp27 was efficient in the suppression of HSV infection. These Hsps may act through suppression of virus entry and/ or through interaction with viral proteins. Thus, it is necessary to determine their exact mechanisms in the near future.

Associations of Heat-Shock Protein Expression with Meat Quality and Sensory Quality Characteristics in Highly Marbled Longissimus Thoracis Muscle from Hanwoo Steers Categorized by Warner-Bratzler Shear Force Value

The influence of heat-shock protein (HSP) concentrations at 45 min and 24 h postmortem on meat quality and sensory quality characteristics of longissimus thoracis muscle from highly marbled Hanwoo steers (beef marbling standard grade 6–8) was investigated. Muscle samples were segregated into three groups based on Warner–Bratzler shear force (WBSF) value. The low group exhibited a lower WBSF value compared to the medium and high groups (37.8 vs. 48.9 and 64.3 N, p < 0.001). Muscle pH at 45 min and 24 h postmortem was not different (p > 0.05), and all groups exhibited low ultimate pH value (pH < 5.8). Beef steaks from the low group were significantly easier to pierce and chew, and they left less perceptible residue than the high group (p < 0.05). These differences in tenderness attributes were associated with differences in small HSPs at 45 min postmortem, with the low group exhibiting a lower level of αβ-crystallin and higher levels of HSP20 and HSP27 compared with the high group (p < 0.05). No differences were observed for small HSPs, HSP70, and HSP90 at 24 h postmortem (p > 0.05). Therefore, the expression levels of small HSPs at 45 min postmortem seems to have the potential to be an indicator of tenderness in highly marbled Hanwoo beef with low ultimate pH.

Proteomic analysis of human periodontal ligament cells under hypoxia

Background

The periodontal ligament is essential for homeostasis of periodontal tissue. A hypoxic milieu of the periodontal tissue is generated under periodontitis or during orthodontic treatment, which affects the periodontal and bone remodelling process. Here, we provide a comprehensive proteomic characterization of periodontal ligament cells under hypoxic conditions, aiming to reveal previously unappreciated biological changes and to help advance hypoxia-based therapeutic strategies for periodontal diseases.

Methods

Human periodontal ligament cells (hPDLCs) were characterized using immunohistochemistry (IHC) and flow cytometry (FACS). Successful hypoxia treatment of hPDLCs with 1% O₂ was confirmed by qRT-PCR. Proliferation was evaluated using an MTT assay. The proteomic expression profile under hypoxia was studied with the isobaric tags for relative and absolute quantification (iTRAQ) approach followed by protein identification and bioinformatic analysis, and western blot verification was performed.

Results

The hPDLCs were positive for vimentin, CD73 and CD105 and negative for keratin, CD34 and CD45. After hypoxia treatment, the mRNA expression of hypoxia-inducible factor 1a (HIF1a) was upregulated. The proliferation rate was elevated during the first 6 h but decreased from 6 h to 72 h. A total of 220 differentially expressed proteins were quantified in hPDLCs under hypoxia (1% O₂, 24 h), including 153 upregulated and 67 downregulated proteins, five of which were verified by western blot analysis. The Gene Ontology enriched terms included the energy metabolic process, membrane-bound organelle and vesicle, and protein binding terms. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated several involved pathways, including glycolysis/gluconeogenesis, biosynthesis of amino acids, the HIF-1 signalling pathway, and focal adhesion. A protein–protein interaction (PPI) network demonstrated the dominant role of autophagy over apoptosis under hypoxia.

Conclusion

The proteomic profile of hPDLCs under hypoxia was mainly related to energy metabolism, autophagy, and responses to stimuli such as adhesion and inflammation. Previously unrecognized proteins including solute carrier family proteins, heat shock proteins, ubiquitination-related enzymes, collagen and S100 family proteins are involved in adaptive response to hypoxia in hPDLCs and are thus of great research interest in future work.

Electronic supplementary material

The online version of this article (10.1186/s12953-019-0151-2) contains supplementary material, which is available to authorized users.

Comparative proteomic profiling of human dental pulp stem cells and periodontal ligament stem cells under in vitro osteogenic induction

OBJECTIVE

This study aimed to compare the proteomic profiling of human dental pulp stem cells (DPSCs) and periodontal ligament stem cells (PDLSCs) under in vitro osteogenic induction, which imitates the microenvironment during osteo-/odontogenesis of DPSCs and PDLSCs.

DESIGN

The proteomic profiles of osteoinduced DPSCs and PDLSCs from a single donor were compared using the isobaric tag for relative and absolute quantitation (iTRAQ) technique and subsequent bioinformatics analysis.

RESULTS

A total of 159 differentially expressed proteins in PDLSCs and DPSCs were identified, 82 of which had a higher expression level in PDLSCs, while 77 were more highly expressed in DPSCs. Among these enriched proteins, certain members from the collagen, heat shock protein and protein S100 families may distinguish osteoinduced PDLSCs and DPSCs. Gene ontology (GO) classification revealed that a large number of the enriched terms distinguishing PDLSCs and DPSCs are involved in catalytic activity, protein binding, regulation of protein metabolic processes and response to stimulus. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis indicated several involved pathways, including the fatty acid biosynthesis pathway, pantothenate and CoA biosynthesis pathway, arachidonic acid metabolism pathway and PPAR signaling pathway. Further verification showed that the mineralization and migration capacities of PDLSCs were greater than those of DPSCs, in which heat shock protein beta-1, Protein S100-A10 and S100-A11 may play a part.

CONCLUSIONS

Less than 5% of the differentially expressed proteins make up the comparative proteomic profile between osteoinduced PDLSCs and DPSCs. This study helps to characterize the differences between osteoinduced PDLSCs and DPSCs in vitro.

Analysis of HspB1 (Hsp27) Oligomerization and Phosphorylation Patterns and Its Interaction with Specific Client Polypeptides

Human HspB1 (also denoted as Hsp27) belongs to the family of small (or stress) proteins (sHsps). The family, which contains ten members including αA,B-crystallin polypeptides, is characterized by a conserved C-terminal α-crystallin domain and molecular weights ranging from 20 to 40 kDa. Here, procedures are described for analyzing the dynamic oligomerization and phosphorylation patterns of HspB1 in cells exposed to different environments. Changes in the structural organization of HspB1 can reprogram its interaction with specific partner/client polypeptides. Methods are presented to analyze these interactions using tissue culture cells genetically modified to express different levels of this protein. In addition, the laboratory approaches presented here could be used to test the nine other human sHsp members as well as sHsps from other species.

Mammalian HspB1 (Hsp27) is a molecular sensor linked to the physiology and environment of the cell

Constitutively expressed small heat shock protein HspB1 regulates many fundamental cellular processes and plays major roles in many human pathological diseases. In that regard, this chaperone has a huge number of apparently unrelated functions that appear linked to its ability to recognize many client polypeptides that are subsequently modified in their activity and/or half-life. A major parameter to understand how HspB1 is dedicated to interact with particular clients in defined cellular conditions relates to its complex oligomerization and phosphorylation properties. Indeed, HspB1 structural organization displays dynamic and complex rearrangements in response to changes in the cellular environment or when the cell physiology is modified. These structural modifications probably reflect the formation of structural platforms aimed at recognizing specific client polypeptides. Here, I have reviewed data from the literature and re-analyzed my own studies to describe and discuss these fascinating changes in HspB1 structural organization.

Asymmetrical Polymer Vesicles for Drug delivery and Other Applications

Scientists have been attracted by polymersomes as versatile drug delivery systems since the last two decades. Polymersomes have the potential to be versatile drug delivery systems because of their tunable membrane formulations, stabilities in vivo, various physicochemical properties, controlled release mechanisms, targeting abilities, and capacities to encapsulate a wide range of drugs and other molecules. Asymmetrical polymersomes are nano- to micro-sized polymeric capsules with asymmetrical membranes, which means, they have different outer and inner coronas so that they can exhibit better endocytosis rate and endosomal escape ability than other polymeric systems with symmetrical membranes. Hence, asymmetrical polymersomes are highly promising as self-assembled nano-delivery systems in the future for in vivo therapeutics delivery and diagnostic imaging applications. In this review, we prepared a summary about recent research progresses of asymmetrical polymersomes in the following aspects: synthesis, preparation, applications in drug delivery and others.

Stage and cell-specific expression and intracellular localization of the small heat shock protein Hsp27 during oogenesis and spermatogenesis in the Mediterranean fruit fly, Ceratitis capitata

The cell-specific expression and intracellular distribution of the small heat protein Hsp27 was investigated in the ovaries and testes of the Mediterranean fruit fly, Ceratitis capitata (medfly), under both normal and heat shock conditions. For this study, a gfp-hsp27 strain was used to detect the chimeric protein by confocal microscopy. In unstressed ovaries, the protein was expressed throughout egg development in a stage and cell-specific pattern. In germarium, the protein was detected in the cytoplasm of the somatic cells in both unstressed and heat-shocked ovaries. In the early stages of oogenesis of unstressed ovaries, the protein was mainly located in the perinuclear region of the germ cells and in the cytoplasm of the follicle cells, while in later stages (9-10) it was distributed in the cytoplasm of the germ cells. In late stages (12-14), the protein changed localization pattern and was exclusively associated with the nuclei of the somatic cells. In heat shocked ovaries, the protein was mainly located in the nuclei of the somatic cells throughout egg chamber's development. In unstressed testes, the chimeric protein was detected in the nuclei of primary spermatocytes and in the filamentous structures of spermatid bundles, called actin cones. Interestingly, after a heat shock, the protein presented the same cell-specific localization pattern as in unstressed testes. Furthermore, the protein was also detected in the nuclei of the epithelial cells of the deferent duct, the accessory glands and the ejaculatory bulb. Our data suggest that medfly Hsp27 may have cell-specific functions, especially in the nucleus. Moreover, the association of this protein to actin cones during spermatid individualization, suggests a possible role of the protein in the formation and stabilization of actin cones.

Serum Heat Shock Protein Levels and the Relationship of Heat Shock Proteins with Various Parameters in Chronic Obstructive Pulmonary Disease Patients

OBJECTIVES

Chronic Obstructive Pulmonary Disease (COPD) is accompanied by increased cellular stress and inflammation. Most of the Heat Shock Proteins (HSPs) have strong cytoprotective effects. The role of HSPs in COPD pathogenesis has not determined completely. We investigated the serum level of HSPs in COPD patients, smokers without COPD and healthy non-smoking controls. Also, we evaluated the relationship of HSPs with various parameters (inflammatory, oxidative, functional status, quality of life) in COPD patients.

MATERIAL AND METHODS

The levels of stress protein (HSP27, HSP70, HSP60, HSP90, CyPA), interleukin-6, C-reactive protein and malondialdehyde were measured in 16 healthy non-smoker, 14 smokers without COPD and 50 patients with stable COPD. Pulmonary function tests (PFT) and arterial blood gases parameters were measured. Health Related Quality of Life was evaluated and exercise capacity was measured with 6 minute walking test.

RESULTS

Only HSP27 levels was significantly higher in COPD patients when compared with both healthy non-smoker and smokers without COPD (for both, p< 0.001). There was a weak-moderate negative correlation between serum levels of HSP27 and PFT parameters and between HSP27 levels and PaO2. Serum levels of HSP27 showed a weak-moderate positive correlation with symptom, activity and total scores. Subjects evaluated only smokers without COPD and patients with COPD; HSP27 had an area under the curve (AUC) in the receiver operating characteristic (ROC) curve of 0.819 (0.702-0.935; 95% CI; p= 0.000).

CONCLUSION

Increased serum levels of HSP27 was found in COPD patients and our results showed sensitivity and specificity of serum HSP27 as diagnostic markers for COPD.

The Effects of Thermal Preconditioning on Oncogenic and Intraspinal Cord Growth Features of Human Glioma Cells

The adult rodent spinal cord presents an inhibitory environment for donor cell survival, impeding efficiency for xenograft-based modeling of gliomas. We postulated that mild thermal preconditioning may influence the fate of the implanted tumor cells. To test this hypothesis, high-grade human astrocytoma G55 and U87 cells were cultured under 37C and 38.5C to mimic regular experimental or core body temperatures of rodents, respectively. In vitro, the 38.5C-conditioned cells, relative to 37C, grew slightly faster. Compared to U87 cells, G55 cells demonstrated a greater response to the temperature difference. Hyperthermal culture markedly increased production of Hsp27 in most G55 cells, but only promoted transient expression of cancer stem cell marker CD133 in a small cell subpopulation. We subsequently transplanted G55 cells following 37C or 38.5C culture into the C2 or T10 spinal cord of adult female immunodeficient rats (3 rats/each locus/per temperature; total: 12 rats). Systematic analyses revealed that 38.5C-preconditioned G55 cells grew more malignantly at either C2 or T10 as determined by tumor size, outgrowth profile, resistance to bolus intratumor administration of 5-fluorouracil (0.1 mol), and posttumor survival (p0.05; n=6/group). Therefore, thermal preconditioning of glioma cells may be an effective way to influence the in vitro and in vivo oncological contour of glioma cells. Future studies are needed for assessing the potential oncogenic modifying effect of hyperthermia regimens on glioma cells.

Effectiveness of pure argon for renal transplant preservation in a preclinical pig model of heterotopic autotransplantation

BACKGROUND

In kidney transplantation, the conditions of organ preservation following removal influence function recovery. Current static preservation procedures are generally based on immersion in a cold-storage solution used under atmospheric air (approximately 78 kPa N2, 21 kPa O2, 1 kPa Ar). Research on static cold-preservation solutions has stalled, and modifying the gas composition of the storage medium for improving preservation was considered. Organoprotective strategies successfully used noble gases and we addressed here the effects of argon and xenon on graft preservation in an established preclinical pig model of autotransplantation.

METHODS

The preservation solution Celsior saturated with pure argon (Argon-Celsior) or xenon (Xenon-Celsior) at atmospheric pressure was tested versus Celsior saturated with atmospheric air (Air-Celsior). The left kidney was removed, and Air-Celsior (n = 8 pigs), Argon-Celsior (n = 8) or Xenon-Celsior (n = 6) was used at 4 °C to flush and store the transplant for 30 h, a duration that induced ischemic injury in our model when Air-Celsior was used. Heterotopic autotransplantation and contralateral nephrectomy were performed. Animals were followed for 21 days.

RESULTS

The use of Argon-Celsior vs. Air-Celsior: (1) improved function recovery as monitored via creatinine clearance, the fraction of excreted sodium and tubulopathy duration; (2) enabled diuresis recovery 2-3 days earlier; (3) improved survival (7/8 vs. 3/8 pigs survived at postoperative day-21); (4) decreased tubular necrosis, interstitial fibrosis, apoptosis and inflammation, and preserved tissue structures as observed after the natural death/euthanasia; (5) stimulated plasma antioxidant defences during the days following transplantation as shown by monitoring the "reduced ascorbic acid/thiobarbituric acid reactive substances" ratio and Hsp27 expression; (6) limited the inflammatory response as shown by expression of TNF-alpha, IL1-beta and IL6 as observed after the natural death/euthanasia. Conversely, Xenon-Celsior was detrimental, no animal surviving by day-8 in a context where functional recovery, renal tissue properties and the antioxidant and inflammation responses were significantly altered. Thus, the positive effects of argon were not attributable to the noble gases as a group.

CONCLUSIONS

The saturation of Celsior with argon improved early functional recovery, graft quality and survival. Manipulating the gas composition of a preservation medium constitutes therefore a promising approach to improve preservation.

Association between small heat shock protein B11 and the prognostic value of MGMT promoter methylation in patients with high-grade glioma

OBJECT This study investigated the role and prognostic value of heat shock proteins (HSPs) in glioma. METHODS Data from 3 large databases of glioma samples (Chinese Glioma Genome Atlas, Repository for Molecular Brain Neoplasia Data, and GSE16011), which contained whole-genome messenger RNA microarray expression data and patients' clinical data, were analyzed. Immunohistochemical analysis was performed to validate protein expression in another set of 50 glioma specimens. RESULTS Of 28 HSPs, 11 were overexpressed in high-grade glioma (HGG) compared with low-grade glioma. A univariate Cox analysis revealed that HSPB11 has significant prognostic value for each glioma grade, which was validated by a Kaplan-Meier survival analysis. HSPB11 expression was associated with poor prognosis and was independently correlated with overall survival (OS) in HGG. This study further explored the combined role of HSPB11 and other molecular markers in HGG, such as isocitrate dehydrogenase 1 (IDH1) mutation and O(6)-methylguanine-DNA methyltransferase (MGMT) promoter methylation status. HSPB11 expression was able to refine the prognostic value of IDH1 mutation in patients with HGG. However, when combined with MGMT promoter methylation status, among patients with a methylated MGMT promoter, those with lower levels of HSPB11 expression had longer OS and progression-free survival than patients with higher levels of HSPB11 expression or with an unmethylated MGMT promoter. Moreover, within the MGMT promoter methylation group, patients with low levels of HSPB11 expression were more sensitive to combined radiochemotherapy than those with high levels of HSPB11 expression, which may explain why some patients with HGG with a methylated MGMT promoter show tolerance to radiochemotherapy. CONCLUSIONS HSPB11 was identified as a novel prognostic marker in patients with HGG. Together with MGMT promoter methylation status, HSPB11 expression can predict outcome for patients with HGG and identify those who would most benefit from combined radiochemotherapy.

Small heat-shock proteins: important players in regulating cellular proteostasis

Small heat-shock proteins (sHsps) are a diverse family of intra-cellular molecular chaperone proteins that play a critical role in mitigating and preventing protein aggregation under stress conditions such as elevated temperature, oxidation and infection. In doing so, they assist in the maintenance of protein homeostasis (proteostasis) thereby avoiding the deleterious effects that result from loss of protein function and/or protein aggregation. The chaperone properties of sHsps are therefore employed extensively in many tissues to prevent the development of diseases associated with protein aggregation. Significant progress has been made of late in understanding the structure and chaperone mechanism of sHsps. In this review, we discuss some of these advances, with a focus on mammalian sHsp hetero-oligomerisation, the mechanism by which sHsps act as molecular chaperones to prevent both amorphous and fibrillar protein aggregation, and the role of post-translational modifications in sHsp chaperone function, particularly in the context of disease.

A proteomic approach to monitor the dynamic response of the female oviductal epithelial cell surface to male gametes

Sophisticated strategies to analyze cell surface proteins are indispensable to study fundamental biological processes, such as the response of cells to environmental changes or cell-cell communication. Herein, we describe a refined mass spectrometry-based approach for the specific characterization and quantitation of cell surface proteins expressed in the female reproductive tract. The strategy is based on in situ biotinylation of rabbit oviducts, affinity enrichment of surface exposed biotin tagged proteins and dimethyl labeling of the obtained tryptic peptides followed by LC-MS/MS analysis. This approach proved to be sensitive enough to analyze small sample amounts (<1μg) and allowed further to trace the dynamic composition of the surface proteome of the oviductal epithelium in response to male gametes. The relative protein expression ratios of 175 proteins were quantified. Thirty-one of them were found to be altered over time, namely immediately, 1h and 2h after insemination compared to the time-matched control groups. Functional analysis demonstrated that structural reorganization of the oviductal epithelial cell surface was involved in the early response of the female organ to semen. In summary, this study outlines a workflow that is capable to monitor alterations in the female oviduct that are related to key reproductive processes in vivo.

BIOLOGICAL SIGNIFICANCE

The proper interaction between the female reproductive tract, in particular, the oviduct and the male gametes, is fundamental to fertilization and embryonic development under physiological conditions. Thereby the oviductal epithelial cell surface proteins play an important role. Besides their direct interaction with male gametes, these molecules participate in signal transduction and, thus, are involved in the mandatory cellular response of the oviductal epithelium. In this study we present a refined LC-MS/MS based workflow that is capable to quantitatively analyze the expression of oviductal epithelial cell surface proteins in response to insemination in vivo. A special focus was on the very early interaction between the female organ and the male gametes. At first, this study clearly revealed an immediate response of the surface proteome to semen, which was modulated over time. The described methodology can be applied for studies of further distinct biological events in the oviduct and therefore contribute to a deeper insight into the formation of new life.

Effect of IR laser on myoblasts: a proteomic study

Laser therapy is used in physical medicine and rehabilitation to accelerate muscle recovery and in sports medicine to prevent damages produced by metabolic disturbances and inflammatory reactions after heavy exercise. The aim of this research was to get insight into possible benefits deriving from the application of an advanced IR laser system to counteract deficits of muscle energy metabolism and stimulate the recovery of hypotrophic tissue. We studied the effect of IR laser treatment on proliferation, differentiation, cytoskeleton organization and global protein expression in C2C12 myoblasts. We found that laser treatment induced a decrease in the cell proliferation rate without affecting cell viability, while leading to cytoskeletal rearrangement and expression of the early differentiation marker MyoD. The differential proteome analysis revealed the up-regulation and/or modulation of many proteins known to be involved in cell cycle regulation, cytoskeleton organization and differentiation.

Small heat shock protein degradation could be an indicator of the extent of myofibrillar protein degradation

The objective of the present study was to evaluate the relationship between small heat shock proteins (sHSP) degradation and tenderness development of beef loins at different ultimate pH (pHu). A total of twelve loins (M. longissimus dorsi) from steers were obtained at 1 day post mortem. Shear force and proteolysis of each loin were analyzed at 1 and 28 days post mortem. The loins at intermediate pHu (5.8 to 6.0) showed more variation in tenderness compared to the loins at low pHu (<5.8), where few samples were still tough (>10kgF) at 28days. The intact sHSP20 was more pronounced (P<0.05) in the intermediate pHu loin compared to the low pHu counterpart. Further, high correlations between the degradation of both sHSP and myofibrillar proteins were observed (e.g. r=0.94; degraded sHSP27 and degraded desmin). The result of this study suggests that the extent of sHSP degradation could be an indicator of myofibrillar protein degradation and tenderness.

Noncanonical cell death in the nematode Caenorhabditis elegans

The nematode Caenorhabditis elegans has served as a fruitful setting for cell death research for over three decades. A conserved pathway of four genes, egl-1/BH3-only, ced-9/Bcl-2, ced-4/Apaf-1, and ced-3/caspase, coordinates most developmental cell deaths in C. elegans. However, other cell death forms, programmed and pathological, have also been described in this animal. Some of these share morphological and/or molecular similarities with the canonical apoptotic pathway, while others do not. Indeed, recent studies suggest the existence of an entirely novel mode of programmed developmental cell destruction that may also be conserved beyond nematodes. Here, we review evidence for these noncanonical pathways. We propose that different cell death modalities can function as backup mechanisms for apoptosis, or as tailor-made programs that allow specific dying cells to be efficiently cleared from the animal.

Distinct patterns of HSP30 and HSP70 degradation in Xenopus laevis A6 cells recovering from thermal stress

Heat shock proteins (HSPs) are molecular chaperones that assist in protein synthesis, folding and degradation and prevent stress-induced protein aggregation. In this study, we examined the pattern of accumulation of HSP30 and HSP70 in Xenopus laevis A6 kidney epithelial cells recovering from heat shock. Immunoblot analysis revealed the presence of elevated levels of HSP30 after 72h of recovery. However, the relative levels of HSP70 declined to near control levels after 24h. The relative levels of both hsp30 and hsp70 mRNA were reduced to low levels after 24h of recovery from heat shock. Pretreatment of cells with cycloheximide, a translational inhibitor, produced a rapid decline in HSP70 but not HSP30. The cycloheximide-associated decline of HSP70 was blocked by the proteasomal inhibitor, MG132, but had little effect on the relative level of HSP30. Also, treatment of cells with the phosphorylation inhibitor, SB203580, in addition to cycloheximide treatment enhanced the stability of HSP30 compared to cycloheximide alone. Immunocytochemical studies detected the presence of HSP30 accumulation in a granular pattern in the cytoplasm of recovering cells and its association with aggresome-like structures, which was enhanced in the presence of SB203580. This study has shown that the relative levels of heat shock-induced HSP30 persist during recovery in contrast to HSP70. While HSP70 is degraded by the ubiquitin-proteasome system, it is likely that the presence of HSP30 multimeric complexes that are known to associate with unfolded protein as well as its association with aggresome-like structures may delay its degradation.

B7H4, HSP27 and DJ-1 molecular markers as prognostic factors in pancreatic cancer

OBJECTIVES

Pancreatic cancer (PC) is one of the most lethal tumors of the gastrointestinal tract. The ability to predict which patients would benefit most from surgical intervention and chemotherapy would be a great clinical tool. A large number of potential markers have been identified lately in pancreatic cancer and their clinical utilities as prognostic tools are under investigation.

METHODS

We recruited 41 patients who had undergone radical surgical resection for PC between 2003 and 2010. To investigate the prognostic factors, we evaluated 3 possible markers: B7H4, HSP27 and DJ-1 protein expressions in the tissue specimens of these 41 patients by immunohistochemistry and analyzed the clinical and pathological features of these specimens.

RESULTS

The expression of the three antigens was independently associated with a negative impact of chemotherapy with gemcitabine on patient's survival. Moreover, patients who overexpressed B7H4 had worse prognosis than the ones who did not.

CONCLUSIONS

B7H4, DJ-1 and HSP27 may be used in the future as prognostic markers that express resistance of pancreatic cancer patients to chemotherapy with gemcitabine.

Pathology-dependent effects linked to small heat shock proteins expression: an update

Small heat shock proteins (small Hsps) are stress-induced molecular chaperones that act as holdases towards polypeptides that have lost their folding in stress conditions or consequently of mutations in their coding sequence. A cellular protection against the deleterious effects mediated by damaged proteins is thus provided to cells. These chaperones are also highly expressed in response to protein conformational and inflammatory diseases and cancer pathologies. Through specific and reversible modifications in their phospho-oligomeric organization, small Hsps can chaperone appropriate client proteins in order to provide cells with resistance to different types of injuries or pathological conditions. By helping cells to better cope with their pathological status, their expression can be either beneficial, such as in diseases characterized by pathological cell degeneration, or deleterious when they are required for tumor cell survival. Moreover, small Hsps are actively released by cells and can act as immunogenic molecules that have dual effects depending on the pathology. The cellular consequences linked to their expression levels and relationships with other Hsps as well as therapeutic strategies are discussed in view of their dynamic structural organization required to interact with specific client polypeptides.

Cellular internalization and stress response of ingested amorphous silica nanoparticles in the midgut of Drosophila melanogaster

BACKGROUND

Amorphous silica nanoparticles (aSNPs) are used for various applications including food industry. However, limited in vivo studies are available on absorption/internalization of ingested aSNPs in the midgut cells of an organism. The study aims to examine cellular uptake of aSNPs (<30nm) in the midgut of Drosophila melanogaster (Oregon R(+)) owing to similarities between the midgut tissue of this organism and human and subsequently cellular stress response generated by these nanoparticles.

METHODS

Third instar larvae of D. melanogaster were exposed orally to 1-100μg/mL of aSNPs for 12-36h and oxidative stress (OS), heat shock genes (hsgs), membrane destabilization (Acridine orange/Ethidium Bromide staining), cellular internalization (TEM) and apoptosis endpoints.

RESULTS

A significant increase was observed in OS endpoints in the midgut cells of exposed Drosophila in a concentration- and time-dependent manner. Significantly increased expression of hsp70 and hsp22 along with caspases activation, membrane destabilization and mitochondrial membrane potential loss was also observed. TEM analysis showed aSNPs-uptake in the midgut cells of exposed Drosophila via endocytic vesicles and by direct membrane penetration.

CONCLUSION

aSNPs after their internalization in the midgut cells of exposed Drosophila larvae show membrane destabilization along with increased cellular stress and cell death.

GENERAL SIGNIFICANCE

Ingested aSNPs show adverse effects on the cells of GI tract of the exposed organism thus their industrial use as a food-additive may raise concern to human health.

Functional specific roles of H-ras and N-ras. A proteomic approach using knockout cell lines

Ras small GTPases function as transducers of extracellular signals regulating cell survival, growth and differentiation. There are three major ras isoforms: H-, N- and K-Ras. To improve the understanding of H- and N-Ras protein signalling networks, we compared total proteome changes in mouse embryonic fibroblasts knock out for H-ras and/or N-ras, using proteomics tools combining 2DE, semi-quantitative image analysis, in-gel trypsin digestion and mass spectrometry. There are four up-regulated proteins due to the loss of expression of H-Ras (including cyclin-dependent kinase inhibitor 2A) and eight down-regulated (including stress-70 protein, dihydropyrimidinase-related-protein 3, heat shock cognate 71 kDa protein, tropomyosin beta chain, Rho GDP-dissociation inhibitor 1) and six up-regulated proteins (e.g. leukocyte elastase inhibitor A, L-lactate dehydrogenase B chain, c-Myc-responsive protein Rcl, interleukin-1 receptor antagonist protein) due to the loss of expression of both N- and H-Ras. Most of these proteins are related to Ras signalling in one way or another. Changes in expression of some of these proteins were further confirmed by Western blot. This proteomic comparative analysis from loss of function of H- and N-Ras knockout fibroblasts yields interpretable data to elucidate the differential protein expression, and contributes to evaluate the possibilities for physiological and therapeutic targets.

Heat shock proteins and heat shock factor 1 in carcinogenesis and tumor development: an update

Heat shock proteins (HSP) are a subset of the molecular chaperones, best known for their rapid and abundant induction by stress. HSP genes are activated at the transcriptional level by heat shock transcription factor 1 (HSF1). During the progression of many types of cancer, this heat shock transcriptional regulon becomes co-opted by mechanisms that are currently unclear, although evidently triggered in the emerging tumor cell. Concerted activation of HSF1 and the accumulation of HSPs then participate in many of the traits that permit the malignant phenotype. Thus, cancers of many histologies exhibit activated HSF1 and increased HSP levels that may help to deter tumor suppression and evade therapy in the clinic. We review here the extensive work that has been carried out and is still in progress aimed at (1) understanding the oncogenic mechanisms by which HSP genes are switched on, (2) determining the roles of HSF1/HSP in malignant transformation and (3) discovering approaches to therapy based on disrupting the influence of the HSF1-controlled transcriptome in cancer.

L-type calcium channels play a crucial role in the proliferation and osteogenic differentiation of bone marrow mesenchymal stem cells

L-type voltage-dependent Ca(2+) channels (VDCC(L)) play an important role in the maintenance of intracellular calcium homeostasis, and influence multiple cellular processes. They have been confirmed to contribute to the functional activities of osteoblasts. Recently, VDCC(L) expression was reported in mesenchymal stem cells (MSCs), but the role of VDCC(L) in MSCs is still undetermined. The aim of this study was to determine whether VDCC(L) may be regarded as a new regulator in the proliferation and osteogenic differentiation of rat MSC (rMSCs). In this study, we examined functional Ca(2+) currents (I(Ca)) and mRNA expression of VDCC(L) in rMSCs, and then suppressed VDCC(L) using nifedipine (Nif), a VDCC(L) blocker, to investigate its role in rMSCs. The proliferation and osteogenic differentiation of MSCs were analyzed by MTT, flow cytometry, alkaline phosphatase (ALP), Alizarin Red S staining, RT-PCR, and real-time PCR assays. We found that Nif exerts antiproliferative and apoptosis-inducing effects on rMSCs. ALP activity and mineralized nodules were significantly decreased after Nif treatment. Moreover, the mRNA levels of the osteogenic markers, osteocalcin (OCN), bone sialoprotein (BSP), and runt-related transcription factor 2 (Runx2), were also down-regulated. In addition, we transfected α1C-siRNA into the cells to further confirm the role of VDCC(L) in rMSCs, and a similar effect on osteogenesis was found. These results suggest that VDCC(L) plays a crucial role in the proliferation and osteogenic differentiation of rMSCs.

Heat shock proteins in hematopoietic malignancies

Inducible heat shock proteins are molecular chaperones whose expression is increased after many different types of stress. They have a protective function helping the cell to cope with lethal conditions. Their basal expression is low in nonstressed, normal and nontransformed cells. However, in cancer cells and particularly in hematological malignancies, they are surprisingly abundant. Malignant cells have to rewire their metabolic requirements and therefore have a higher need for chaperones. This cancer cell addiction for HSPs is the basis for the use of HSP inhibitors in cancer therapy. HSPs have been shown to interact with different key apoptotic proteins. As a result, HSPs can essentially block the apoptotic pathways at several steps, most of them involving the activation of cystein proteases called caspases. Apoptosis and differentiation are physiological processes that share many common features, for instance, a controlled caspase activation and chromatin condensation are frequently observed. It is, therefore, not surprising that HSPs may be implicated in the differentiation process. HSPs may determine the fate of the cells by orchestrating the decision of apoptosis versus differentiation. This review will focus on the role of HSPs in hematological malignancies and the emerging therapeutic options that are being either proposed or used to target these protective proteins.

Charcot-Marie-Tooth disease and intracellular traffic

Mutations of genes whose primary function is the regulation of membrane traffic are increasingly being identified as the underlying causes of various important human disorders. Intriguingly, mutations in ubiquitously expressed membrane traffic genes often lead to cell type- or organ-specific disorders. This is particularly true for neuronal diseases, identifying the nervous system as the most sensitive tissue to alterations of membrane traffic. Charcot-Marie-Tooth (CMT) disease is one of the most common inherited peripheral neuropathies. It is also known as hereditary motor and sensory neuropathy (HMSN), which comprises a group of disorders specifically affecting peripheral nerves. This peripheral neuropathy, highly heterogeneous both clinically and genetically, is characterized by a slowly progressive degeneration of the muscle of the foot, lower leg, hand and forearm, accompanied by sensory loss in the toes, fingers and limbs. More than 30 genes have been identified as targets of mutations that cause CMT neuropathy. A number of these genes encode proteins directly or indirectly involved in the regulation of intracellular traffic. Indeed, the list of genes linked to CMT disease includes genes important for vesicle formation, phosphoinositide metabolism, lysosomal degradation, mitochondrial fission and fusion, and also genes encoding endosomal and cytoskeletal proteins. This review focuses on the link between intracellular transport and CMT disease, highlighting the molecular mechanisms that underlie the different forms of this peripheral neuropathy and discussing the pathophysiological impact of membrane transport genetic defects as well as possible future ways to counteract these defects.

Identification and expression analysis of two small heat shock protein cDNAs from developing seeds of biodiesel feedstock plant Jatropha curcas

Plant small heat shock proteins (sHSPs) are known to be important for environmental stress tolerance and involved in various developmental processes. In this study, two full-length cDNAs encoding sHSPs, designated JcHSP-1 and JcHSP-2, were identified and characterized from developing seeds of a promising biodiesel feedstock plant Jatropha curcas by expressed sequence tag (EST) sequencing of embryo cDNA libraries and rapid amplification of cDNA ends (RACE). JcHSP-1 and JcHSP-2 contained open-reading frames encoding sHSPs of 219 and 157 amino acids, with predicted molecular weights of 24.42kDa and 18.02kDa, respectively. Sequence alignment indicated that both JcHSP-1 and JcHSP-2 shared high similarity with other plant sHSPs. Real-time quantitative RT-PCR analysis showed that the transcriptional level of both JcHSP-1 and JcHSP-2 increased along with natural dehydration process during seed development. A sharp increase of JcHSP-2 transcripts occurred in response to water content dropping from 42% in mature seeds to 12% in dry seeds. Western blot analysis revealed that the accumulation profile of two cross-reacting proteins, whose molecular weight corresponding to the calculated size of JcHSP-1 and JcHSP-2, respectively, was well consistent with the mRNA expression pattern of JcHSP-1 and JcHSP-2 in jatropha seeds during maturation and natural dehydration. These results indicated that both JcHSPs might play an important role in cell protection and seed development during maturation of J. curcas seeds.

Structure-functions of HspB1 (Hsp27)

Human HspB1 (also denoted Hsp27) is a well-known member, together with alphaB-crystallin, of the small heat-shock (or stress) proteins (sHsps) (20-40 kDa). In this chapter, I describe procedures for testing the oligomeric and phosphorylation patterns of HspB1 as well as its interaction with specific partner/client polypeptides using tissue culture cells genetically modified to express different levels of this protein. The procedures have been developed in my laboratory and could be used in any well-established cellular laboratory. In addition, the different procedures presented here could be extended to test the nine other human sHsp members as well as sHsps from other species.

Molecular characterization of heat shock proteins 90 (HSP83?) and 70 in tropical strains of Bombyx mori

Following the concept of whole organism, we have extracted total protein from the Bombyx mori for the identification and analysis of HSPs. Expression of 90 kDa HSP in first, second and third instars, 84 kDa in fourth instar and 90-, 84-, 62-, 60-, 52- and 33-kDa HSPs in fifth instar larvae of tropical polyvoltine and bivoltine silkworm strains were obvious. Further, we have combined single and 2-DE with MALDI-TOF for analysis of BmHSPs. Ninety kilodalton band excised from 1-DE gel was identified as HSP83 by MALDI-TOF-MS. The immunoblot analysis confirmed the expression of HSP90 in all the instars larvae of B. mori. Heat shock-induced protein spots were excised from 2-DE gels for MALDI-TOF-MS analysis. The Mascot search results are for HSP68, HSC70-1 and HSP70Ba in Pure Mysore, and major HSP70Bbb, HSP68, HSC-3 and HSP83 in NB(4)D(2). Multiple sequence alignment explicit the variations in amino acid sequence between Pure Mysore and NB(4)D(2). Notably, the PMF of spot 2 matched the coding sequence of B. mori and its gene annotation was determined on chromosome 9. With this novel approach, expression of BmHSP90 was confirmed in all the instars and uncovered isoforms of BmHSP70, which provided unequivocal insight to analyze and understand the biological significance in B. mori.

Serine 59 phosphorylation of {alpha}B-crystallin down-regulates its anti-apoptotic function by binding and sequestering Bcl-2 in breast cancer cells

The small heat shock protein (sHSP) αB-crystallin is a new oncoprotein in breast carcinoma that predicts poor clinical outcome in breast cancer. However, although several reports have demonstrated that phosphorylation of sHSPs modify their structural and functional properties, the significance of αB-crystallin phosphorylation in cancer cells has not yet been investigated. In this study, we have characterized the phosphorylation status of αB-crystallin in breast epithelial carcinoma cells line MCF7 submitted to anti-cancer agents like vinblastine. We have showed that the main phosphorylation site of αB-crystallin in response to vinblastine is serine 59 and determined a correlation between this post-translational modification and higher apoptosis level. The overexpression of the serine 59 "pseudophosphorylated" mutant (S59E) induces a significant increase in the apoptosis level of vinblastine-treated MCF7 cells. In contrast, overexpression of wild-type αB-crystallin or "nonphosphorylatable" mutant (S59A) result in a resistance to this microtubule-depolymerizing agent, while inhibition of endogenous levels of αB-crystallin by expression of shRNA lowers it. Analyzing further the molecular mechanism of this phenomenon, we report for the first time that phosphorylated αB-crystallin preferentially interacts with Bcl-2, an anti-apoptotic protein, and this interaction prevents the translocation of Bcl-2 to mitochondria. Hence, this study identifies serine 59 phosphorylation as an important key in the down-regulation of αB-crystallin anti-apoptotic function in breast cancer and suggests new strategies to improve anti-cancer treatments.

Cypermethrin elicited responses in heat shock protein and feeding in Caenorhabditis elegans

Heat shock proteins (Hsp) are a family of stress proteins, which are elicited in response to a variety of stressors in organisms. The objective of this study was to explore the potential of cypermethrin, a synthetic pyrethroid insecticide, on induction of small heat shock proteins (Hsp16) and feeding response in transgenic Caenorhabditis elegans PC72 (Hsp16-LacZ). A concentration-dependent inhibition in feeding was evident in worms exposed to cypermethrin (31%, 46% and 56% at 5, 10, 15 mM, respectively) beyond 4h while marked induction of heat shock protein-16 expression was evident after 12h exposure (as evident from quantitative analysis). Maximum expression of Hsp16 was observed throughout the body of the worms 24h after exposure similar to that evident in the worms exposed to heat shock at 30 degrees C. These data suggest that cypermethrin possesses the potential to induce Hsp16 as well as inhibit feeding in C. elegans at non-lethal concentrations. C. elegans (PC72) thus could serve as a convenient model to study the early toxic effects of xenobiotics.

Silkworm thermal biology: a review of heat shock response, heat shock proteins and heat acclimation in the domesticated silkworm, Bombyx mori

Heat shock proteins (HSPs) are known to play ecological and evolutionary roles in this postgenomic era. Recent research suggests that HSPs are implicated in cardiovascular biology and disease development, proliferation and regulation of cancer cells, cell death via apoptosis, and several other key cellular functions. These activities have generated great interest amongst cell and molecular biologists, and these biologists are keen to unravel other hitherto unknown potential functions of this group of proteins. Consequently, the biological significance of HSPs has led to cloning and characterization of genes encoding HSPs in many organisms including the silkworm, Bombyx mori L. (Lepidoptera: Bombycidae). However, most of the past investigations in B. mori were confined to expression of HSPs in tissues and cell lines, whereas information on their specific functional roles in biological, physiological, and molecular processes is scarce. Naturally occurring or domesticated polyvoltines (known to be the tropical race) are more resistant to high temperatures and diseases than bi- or univoltines (temperate races). The mechanism of ecological or evolutionary modification of HSPs during the course of domestication of B. mori - particularly in relation to thermotolerance in geographically distinct races/strains - is still unclear. In addition, the heat shock response, thermal acclimation, and hardening have not been studied extensively in B. mori compared to other organisms. Towards this, recent investigations on differential expression of HSPs at various stages of development, considering the concept of the whole organism, open ample scope to evaluate their biological and commercial importance in B. mori which has not been addressed in any of the representative organisms studied so far. Comparatively, heat shock response among different silkworm races/strains of poly-, bi-, and univoltines varies significantly and thermotolerance increases as the larval development proceeds. Hence, this being the first review in this area, an attempt has been made to collate all available information on the heat shock response, HSPs expression, associated genes, amino acid sequences, and acquired/unacquired thermotolerance. The aim is to present this as a valuable resource for addressing the gap in knowledge and understanding evolutionary significance of HSPs between domesticated (B. mori) and non-domesticated insects. It is believed that the information presented here will also help researchers/breeders to design appropriate strategies for developing novel strains for the tropics.

Small Interfering RNA-Mediated Silencing of Heat Shock Protein 27 (HSP27) Increases Chemosensitivity to Paclitaxel by Increasing Production of Reactive Oxygen Species in Human Ovarian Cancer Cells (HO8910)

Increasing evidence indicates that reactive oxygen species (ROS) are involved in paclitaxel cytotoxicity. Modulating the oxidant–antioxidant status of tumour cells may increase the antitumour activity of paclitaxel. The cytoprotective roles of heat shock protein 27 (HSP27) include chaperoning cellular proteins, regulating apoptotic signalling and modulating oxidative stress. Immunohistochemical staining for HSP27 in human ovarian cancer specimens showed HSP27 was associated with aggressive malignant ovarian disease. Small interfering RNA (siRNA) was used to down-regulate HSP27 in human ovarian cancer cells (HO8910). Reduction of HSP27 expression increased the in vitro chemosensitivity of HO8910 cells to paclitaxel and increased paclitaxel-induced apoptosis and ROS production, although the ROS scavenger, N-acetyl-l-cysteine, partly offset the effects of HSP27 siRNA. Thus, gene knock-down of HSP27 offsets the role of this protein in resisting oxidant stress, thereby indirectly increasing the sensitivity of cells to paclitaxel. The siRNA-induced knock-down of HSP27 could be a novel and potent strategy to help overcome chemotherapeutic resistance to paclitaxel in epithelial ovarian cancer cells.

Loss of specific chaperones involved in membrane glycoprotein biosynthesis during the maturation of human erythroid progenitor cells

The production of erythrocytes requires the massive synthesis of red cell-specific proteins including hemoglobin, cytoskeletal proteins, as well as membrane glycoproteins glycophorin A (GPA) and anion exchanger 1 (AE1). We found that during the terminal differentiation of human CD34(+) erythroid progenitor cells in culture, key components of the endoplasmic reticulum (ER) protein translocation (Sec61alpha), glycosylation (OST48), and protein folding machinery, chaperones BiP, calreticulin (CRT), and Hsp90 were maintained to allow efficient red cell glycoprotein biosynthesis. Unexpected was the loss of calnexin (CNX), an ER glycoprotein chaperone, and ERp57, a protein-disulfide isomerase, as well as a major decrease of the cytosolic chaperones, Hsc70 and Hsp70, components normally involved in membrane glycoprotein folding and quality control. AE1 can traffic to the cell surface in mouse embryonic fibroblasts completely deficient in CNX or CRT, whereas disruption of the CNX/CRT-glycoprotein interactions in human K562 cells using castanospermine did not affect the cell-surface levels of endogenous GPA or expressed AE1. These results demonstrate that CNX and ERp57 are not required for major glycoprotein biosynthesis during red cell development, in contrast to their role in glycoprotein folding and quality control in other cells.