HSPs under Abiotic Stresses

Different organisms respond to the altered environmental conditions by different ways. Heat shock proteins’ (HSPs) production is one among the different defense mechanisms which defend the photosystem II and thylokoid membrane in plants. There are different types of HSPs based on their size, that is, high molecular weight (60–100 kDa) and low molecular weight heat shock proteins (15–30 kDa). Small HSPs are further classified based on their localization and role in different sub-cellular organelles. Cp-sHSPs are the chloroplast-specific small HSPs that protect the photosystem II and thylokoid membrane. A model to control the Cp-sHSPs in Chenopodium album has been put forward in this chapter. According to this model, Cp-sHSPs of Chenopodium album are created in cytoplasm and are moved toward chloroplast. The transit peptide is removed on reaching to the target sub-cellular organelle, that is, chloroplast and the premature Cp-sHSPs are converted into mature ones which have multiple roles under different abiotic stress conditions.

Chaperone Networks in Fungal Pathogens of Humans

The heat shock proteins (HSPs) function as chaperones to facilitate proper folding and modification of proteins and are of particular importance when organisms are subjected to unfavourable conditions. The human fungal pathogens are subjected to such conditions within the context of infection as they are exposed to human body temperature as well as the host immune response. Herein, the roles of the major classes of HSPs are briefly reviewed and their known contributions in human fungal pathogens are described with a focus on Candida albicans, Cryptococcus neoformans, and Aspergillus fumigatus. The Hsp90s and Hsp70s in human fungal pathogens broadly contribute to thermotolerance, morphological changes required for virulence, and tolerance to antifungal drugs. There are also examples of J domain co-chaperones and small HSPs influencing the elaboration of virulence factors in human fungal pathogens. However, there are diverse members in these groups of chaperones and there is still much to be uncovered about their contributions to pathogenesis. These HSPs do not act in isolation, but rather they form a network with one another. Interactions between chaperones define their specific roles and enhance their protein folding capabilities. Recent efforts to characterize these HSP networks in human fungal pathogens have revealed that there are unique interactions relevant to these pathogens, particularly under stress conditions. The chaperone networks in the fungal pathogens are also emerging as key coordinators of pathogenesis and antifungal drug tolerance, suggesting that their disruption is a promising strategy for the development of antifungal therapy.

Cellular Functions of Small Heat Shock Proteins (HSPB) in Hepatocellular Carcinoma

Heat shock proteins (HSPs) play an essential role as molecular chaperones in proteostasis. Small HSPs are a group of low-molecular-weight HSPs in the range of 12-43 kDa and are classified as HSPB. Within the ten members of the family, HSPB1 (HSP27), HSPB5 (B-crystallin), HSPB6 (HSP20), and HSPB8 (HSP22) ubiquitously exist in various tissues, including liver tissue. These small HSPs undergo phosphorylation as a post-translational modification, and their functions are modulated. Hepatocellular carcinoma (HCC) is one of the most frequent cancers and the fourth leading cause of cancer-related death worldwide. HSPs play a cytoprotective role as molecular chaperones. Thus, HSPB has been generally considered to protect HCC cells and help the progression of HCC. On the other hand, recent studies from our laboratories have demonstrated suppressive roles of phospho-HSPB1, HSPB6, and HSPB8 in progression of HCC. These findings may provide a basis for a novel defense system by HSPB against HCC progression. This review focuses on the cellular functions of HSPB in HCC and summarizes the current research.

The use of hollow sphere pigments as strength additives in paper and paperboard coatings—Part 2: Optimization in paperboard formulations for opacity and strength

This report aims to summarize the efforts in testing the properties of coatings for paperboard utilizing hollow sphere pigments (HSPs). HSPs are known to effectively scatter light and replace titanium dioxide (TiO2) in architectural coating formulations. The effect of the particle size and void fraction was evaluated, along with many coating parameters, including level of addition, binder chemistry, and blends of two HSPs. The small HSPs that have optimized voids for scattering light showed equivalent strength to the TiO2-containing control. The strength data was surprising, particularly the improvement in strength for coatings containing large particle size HSPs. Because of this increase in strength, four parts of binder could be removed, which allowed for higher brightness while not compromising other properties, including hot melt glueability. These trends held true using different binder chemistries (styrene acrylic, vinyl acrylic, and styrene butadiene). Upon refining the formulations further, blends of two HSPs showed further benefit.

Membrane-Associated Heat Shock Proteins in Oncology: From Basic Research to New Theranostic Targets

Heat shock proteins (HSPs) constitute a large family of conserved proteins acting as molecular chaperones that play a key role in intracellular protein homeostasis, regulation of apoptosis, and protection from various stress factors (including hypoxia, thermal stress, oxidative stress). Apart from their intracellular localization, members of different HSP families such as small HSPs, HSP40, HSP60, HSP70 and HSP90 have been found to be localized on the plasma membrane of malignantly transformed cells. In the current article, the role of membrane-associated molecular chaperones in normal and tumor cells is comprehensively reviewed with implications of these proteins as plausible targets for cancer therapy and diagnostics.

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.

Therapeutic potential of Hsp27 in neurological diseases

Background Heat shock proteins (Hsps) are widely reported in normal cellular dynamics under stress and non-stress conditions, and parallelly, the studies regarding its role in disease condition are also progressing steadily. The function of Hsps in neurodegenerative disorders is puzzling and not fully understood. This review aims to focus on the role of Hsp27 in normal and diseased conditions and emphasize its therapeutic potential. Hsp27 Hsp27, in particular, has shown to be involved in cell viability and actin cytoskeleton remodeling and also shown to improve many disease conditions. Phosphorylated Hsp27 modulates the p53 pathway by downregulating cellular senescence and also lowers reactive oxygen species to protect TNFα-mediated apoptosis. Hsp27 is also known to interfere with mitochondria-dependent and mitochondria-independent cell apoptotic stimulation. Conclusion This article will highlight the various functions of Hsp27 especially as an anti-apoptotic factor and stress response factor and its therapeutic potential in preventing neuronal apoptosis in neurological diseases. This review also includes a comparison of the therapeutic potential of Hsp27 with regard to other small Hsps.

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.

P209L mutation in Bag3 does not cause cardiomyopathy in mice

Bcl-2-associated athanogene 3 (BAG3) is a cochaperone protein and a central player of the cellular protein quality control system. BAG3 is prominently expressed in the heart and plays an essential role in cardiac protein homeostasis by interacting with chaperone heat shock proteins (HSPs) in large, functionally distinct multichaperone complexes. The BAG3 mutation of proline 209 to leucine (P209L), which resides in a critical region that mediates the direct interaction between BAG3 and small HSPs (sHSPs), is associated with cardiomyopathy in humans. However, the mechanism by which the BAG3 P209L missense mutation leads to cardiomyopathy remains unknown. To determine the molecular basis underlying the cardiomyopathy caused by the BAG3 P209L mutation, we generated a knockin (KI) mouse model in which the endogenous Bag3 gene was replaced with mutant Bag3 containing the P215L mutation, which is equivalent to the human P209L mutation. We performed physiological, histological, and biochemical analyses of Bag3 P209L KI mice to determine the functional, morphological, and molecular consequences of the P209L mutation. We found that Bag3 P209L KI mice exhibited normal cardiac function and morphology up to 16 mo of age. Western blot analysis further revealed that levels of sHSPs, stress-inducible HSPs, ubiquitinated proteins, and autophagy were unaffected in P209L mutant mouse hearts. In conclusion, the P209L mutation in Bag3 does not cause cardiomyopathy in mice up to 16 mo of age under baseline conditions. NEW & NOTEWORTHY Bcl-2-associated athanogene 3 (BAG3) P209L mutation is associated with human cardiomyopathy. A recent study reported that transgenic mice overexpressing human BAG3 P209L in cardiomyocytes have cardiac dysfunction. In contrast, our P209L mice that express mutant BAG3 at the same level as that of wild-type mice displayed no overt phenotype. Our results suggest that human cardiomyopathy may result from species-specific requirements for the conserved motif that is disrupted by P209L mutation or from genetic background-dependent effects.