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The heat stress response is an essential defense mechanism in all organisms. Heat shock proteins (Hsps) are produced in response to thermal stress, with their expression levels regulated by heat shock transcription factors. In Escherichia coli, the key transcription factor σ32 positively regulates Hsp expression. Studies from over two decades ago revealed that σ32 abundance is negatively controlled under normal conditions, mainly through degradation mechanisms involving DnaK, GroEL, and FtsH. Beyond this established mechanism, recent findings indicate that a small heat shock protein IbpA also plays a role in the translational regulation of σ32, adding a new layer to the established model. This review highlights the role of a new actor, IbpA, which strongly suppresses σ32 expression under non-stress conditions and markedly increases it during heat shock. [ABSTRACT FROM AUTHOR]

Heat shock transcription factors (HSFs) contribute significantly to thermotolerance acclimation. Here, we identified and cloned a putative HSF gene (HSFA2h) of 1218 nucleotide (acc. no. KP257297.1) from wheat cv. HD2985 using a de novo transcriptomic approach and predicted sHSP as its potential target. The expression of HSFA2h and its target gene (HSP17) was observed at the maximum level in leaf tissue under heat stress (HS), as compared to the control. The HSFA2h-pRI101 binary construct was mobilized in Arabidopsis, and further screening of T3 transgenic lines showed improved tolerance at an HS of 38 °C compared with wild type (WT). The expression of HSFA2h was observed to be 2.9- to 3.7-fold higher in different Arabidopsis transgenic lines under HS. HSFA2h and its target gene transcripts (HSP18.2 in the case of Arabidopsis) were observed to be abundant in transgenic Arabidopsis plants under HS. We observed a positive correlation between the expression of HSFA2h and HSP18.2 under HS. Evaluation of transgenic lines using different physio-biochemical traits linked with thermotolerance showed better performance of HS-treated transgenic Arabidopsis plants compared with WT. There is a need to further characterize the gene regulatory network (GRN) of HSFA2h and sHSP in order to modulate the HS tolerance of wheat and other agriculturally important crops. [ABSTRACT FROM AUTHOR]

Heat shock transcription factors (HSFs) contribute significantly to thermotolerance acclimation. Here, we identified and cloned a putative HSF gene (HSFA2h) of 1218 nucleotide (acc. no. KP257297.1) from wheat cv. HD2985 using a de novo transcriptomic approach and predicted sHSP as its potential target. The expression of HSFA2h and its target gene (HSP17) was observed at the maximum level in leaf tissue under heat stress (HS), as compared to the control. The HSFA2h-pRI101 binary construct was mobilized in Arabidopsis, and further screening of T3 transgenic lines showed improved tolerance at an HS of 38 °C compared with wild type (WT). The expression of HSFA2h was observed to be 2.9- to 3.7-fold higher in different Arabidopsis transgenic lines under HS. HSFA2h and its target gene transcripts (HSP18.2 in the case of Arabidopsis) were observed to be abundant in transgenic Arabidopsis plants under HS. We observed a positive correlation between the expression of HSFA2h and HSP18.2 under HS. Evaluation of transgenic lines using different physio-biochemical traits linked with thermotolerance showed better performance of HS-treated transgenic Arabidopsis plants compared with WT. There is a need to further characterize the gene regulatory network (GRN) of HSFA2h and sHSP in order to modulate the HS tolerance of wheat and other agriculturally important crops.

Small heat shock proteins (sHSPs) have been demonstrated to interact with lipids and modulate the physical state of membranes across species. Through these interactions, sHSPs contribute to the maintenance of membrane integrity. HSPB1 is a major sHSP in mammals, but its lipid interaction profile has so far been unexplored. In this study, we characterized the interaction between HSPB1 and phospholipids. HSPB1 not only associated with membranes via membrane-forming lipids, but also showed a strong affinity towards highly fluid membranes. It participated in the modulation of the physical properties of the interacting membranes by altering rotational and lateral lipid mobility. In addition, the in vivo expression of HSPB1 greatly affected the phase behavior of the plasma membrane under membrane fluidizing stress conditions. In light of our current findings, we propose a new function for HSPB1 as a membrane chaperone. [ABSTRACT FROM AUTHOR]

The angiotensin Converting Enzyme 2 (ACE2) receptor is a key component of the renin-angiotensin-aldesterone system (RAAS) that mediates numerous effects in the cardiovascular system. It is also the cellular point of contact for the coronavirus spike protein. Cleavage of the receptor is both important to its physiological function as well as being necessary for cell entry by the virus. Shedding of ACE2 by the metalloprotease ADAM17 releases a catalytically active soluble form of ACE2, but cleavage by the serine protease TMPRSS2 is necessary for virion internalization. Complicating the issue is the observation that circulating ACE2 can also bind to the virus effectively blocking attachment to the membrane-bound receptor. This work investigates the possibility that the inflammatory response to coronavirus infection can abrogate shedding by ADAM17, thereby favoring cleavage by TMPRSS2 and thus cell entry by the virion. [Display omitted] • An investigation of how the heat shock response to COVID-19 can facilitate cell entry by SARS-CoV-2. • Protein-peptide docking confirms the feasibility of sHsp/ADAM17 complexation. • Protein-protein docking predicts ADAM17 ectodomain complexation to ACE2. [ABSTRACT FROM AUTHOR]

Endoplasmic reticulum stress plays an important role in cardiovascular disease (CVD) and atherosclerosis. We aimed to assess the ability of 4-phenylbutyrate (4-PBA), a small chemical chaperone administered via drinking water, to reduce atherosclerotic lesion size in chow-fed apolipoprotein (Apo) e-/- mice and to identify mechanisms that contribute to its antiatherogenic effect. Chow-fed 17-wk-old female Apoe-/- mice treated with 4-PBA-supplemented drinking water for 5 wk exhibited smaller lesions as well as increased plasma levels of heat shock protein (HSP) 25, the mouse homolog of human HSP27, compared with controls. In addition, 4-PBA inhibited cell death and increased HSP27 expression as measured by real-time PCR and immunoblotting, as well as induced nuclear localization of its transcription factor, heat shock factor 1, in human monocyte/macrophage (THP-1) cells. Furthermore, HSP27 small interfering RNA diminished the protective effect of 4-PBA on THP-1 macrophage attachment and differentiation. In summary, drinking water containing 4-PBA attenuated early lesion growth in Apoe-/- mice fed a chow diet and increased expression of HSP25 and HSP27 in macrophages and HSP25 in the circulation of Apoe-/- mice. Given that increased expression of HSP27 is inversely correlated with CVD risk, our findings suggest that 4-PBA protects against the early stages of atherogenesis in part by enhancing HSP27 levels, leading to inhibition of both macrophage cell death and monocyte-macrophage differentiation.--Lynn, E. G., Lhoták, Š., Lebeau, P., Byun, J. H., Chen, J., Platko, K., Shi, C., O'Brien, E. R., Austin, R. C. 4-Phenylbutyrate protects against atherosclerotic lesion growth by increasing the expression of HSP25 in macrophages and in the circulation of Apoe-/- mice. [ABSTRACT FROM AUTHOR]

BCL2-associated athanogene (BAG)-3 is viewed as a platform that would physically and functionally link distinct classes of molecular chaperones of the heat shock protein (HSP) family for the stabilization and clearance of damaged proteins. In this study, we show that HSPB8, a member of the small heat shock protein subfamily, cooperates with BAG3 to coordinate the sequestration of harmful proteins and the cellular adaptive response upon proteasome inhibition. Silencing of HSPB8, like depletion of BAG3, inhibited targeting of ubiquitinated proteins to the juxtanuclear aggresome, a mammalian system of spatial quality control. However, aggresome targeting was restored in BAG3-depleted cells by a mutant BAG3 defective in HSPB8 binding, uncoupling HSPB8 function from its binding to BAG3. Depletion of HSPB8 impaired formation of ubiquitinated microaggregates in an early phase and interfered with accurate modifications of the stress sensor p62/sequestosome (SQSTM)-1. This impairment correlated with decreased coupling of BAG3 to p62/SQSTM1 in response to stress, hindering Kelch-like ECH-associated protein (KEAP)-1 sequestration and stabilization of nuclear factor E2-related factor (Nrf)-2, an important arm of the antioxidant defense. Notably, the myopathy-associated mutation of BAG3 (P209L), which lies within the HSPB8-binding motif, deregulated the association between BAG3 and p62/SQSTM1 and the KEAP1-Nrf2 signaling axis. Together, our findings support a so-far-unrecognized role for the HSPB8-BAG3 connection in mounting of an efficient stress response, which may be involved in BAG3-related human diseases.--Guilbert, S. M., Lambert, H., Rodrigue, M.-A., Fuchs, M., Landry, J., Lavoie, J. N. HSPB8 and BAG3 cooperate to promote spatial sequestration of ubiquitinated proteins and coordinate the cellular adaptive response to proteasome insufficiency. [ABSTRACT FROM AUTHOR]

Small heat shock proteins (sHSPs) are molecular chaperones important for stress tolerance. In this study, heat induction of a rice sHSP gene OsHSP16.9C is analyzed to understand the molecular mechanisms underlying gene expression regulation in heat shock responses in rice. Promoter deletion analysis of the OsHSP16.9C using the luciferase (LUC) reporter gene in transgenic rice identifies a critical role of a promoter fragment containing an imperfect heat shock element (HSE) in heat induction. HSE was shown to be important for heat induction of AtHSP18.2 , a homolog of OsHSP16.9C in Arabidopsis. In addition, the rice OsHSP16.9C promoter confers heat induction of the reporter gene expression in Arabidopsis. These data suggest that the heat induction mechanisms of OsHSP16.9C and AtHSP18.2 are similar in rice and Arabidopsis. The transgenic reporter line generated offers a system to genetically dissect signaling events in heat induction in rice. [ABSTRACT FROM AUTHOR]

Background: Phosphorylation is one of the most important post-translational modifications (PTM) employed by cells to regulate several cellular processes. Studying the effects of phosphorylations on protein structures allows to investigate the modulation mechanisms of several proteins including chaperones, like the small HSPs, which display different multimeric structures according to the phosphorylation of a few serine residues. In this context, the proposed study is aimed at finding a method to correlate different PTM patterns (in particular phosphorylations at the monomers interface of multimeric complexes) with the dynamic behaviour of the complex, using physicochemical parameters derived from molecular dynamics simulations in the timescale of nanoseconds. Results: We have developed a methodology relying on computing nine physicochemical parameters, derived from the analysis of short MD simulations, and combined with N identifiers that characterize the PTMs of the analysed protein. The nine general parameters were validated on three proteins, with known post-translational modified conformation and unmodified conformation. Then, we applied this approach to the case study of αB-Crystallin, a chaperone which multimeric state (up to 40 units) is supposed to be controlled by phosphorylation of Ser45 and Ser59. Phosphorylation of serines at the dimer interface induces the release of hexamers, the active state of αB-Crystallin. 30 ns of MD simulation were obtained for each possible combination of dimer phosphorylation state and average values of structural, dynamic, energetic and functional features were calculated on the equilibrated portion of the trajectories. Principal Component Analysis was applied to the parameters and the first five Principal Components, which summed up to 84 % of the total variance, were finally considered. Conclusions: The validation of this approach on multimeric proteins, which structures were known both modified and unmodified, allowed us to propose a new approach that can be used to predict the impact of PTM patterns in multi-modified proteins using data collected from short molecular dynamics simulations. Analysis on the αB-Crystallin case study clusters together all-P dimers with all-P hexamers and no-P dimer with no-P hexamer and results suggest a great influence of Ser59 phosphorylation on chain B. [ABSTRACT FROM AUTHOR]

In this study, we investigated physiological changes and transcriptional responses in four-week-old hydroponically grown Medicago sativa seedlings exposed to (PbNO 3 ) 2 (0, 10 and 100 μM) for 2 and 7 days. Fresh weight and length were reduced in both shoots and roots after 7 days exposure. Lead accumulation was time and dose-dependent with stronger phytotoxic effects in roots than in shoots, with a relatively low amount of Pb translocated from roots to shoots. Lipid peroxidation augmented remarkably, suggesting the onset of oxidative damages, with increased glutathione reductase (GR), ascorbate peroxidase (APX) and superoxide dismutase (SOD) activities. This result was accompanied by a remarkable up-regulation of APX and SOD genes. In roots, the increase of SOD transcripts was concomitant to an enhanced SOD enzymatic activity in all Pb treatments. However, the 30-fold up-regulation occurred with a remarkable APX activity inhibition, which suggests that there might be post-transcriptional modifications able to regulate root APX. Root glutathione (GSH) and homoglutathione (hGSH) concentrations decreased in a dose dependent manner, while we could not detect the accumulation of phytochelatins (PC), albeit the related gene was up-regulated. The lack of PCs synthesis suggests a post-translational regulation of its enzymatic activity. Heat shock proteins (HSP70 and HSP17.7) were increased in alfalfa shoots, implying the triggering of cellular protection mechanism to cope with lead phytotoxicity. It is concluded that alfalfa plants mitigate the oxidative damage through induction of antioxidant enzymes, and the expression of chaperone proteins to alleviate Pb toxicity; metabolic changes that could be exploited as Pb-stress bioindicators. [ABSTRACT FROM AUTHOR]

LEAM, a late embryogenesis abundant protein, and HSP22, a small heat shock protein, were shown to accumulate in the mitochondria during pea ( P isum sativum L.) seed development, where they are expected to contribute to desiccation tolerance. Here, their expression was examined in seeds of 89 pea genotypes by Western blot analysis. All genotypes expressed LEAM and HSP22 in similar amounts. In contrast with HSP22, LEAM displayed different isoforms according to apparent molecular mass. Each of the 89 genotypes harboured a single LEAM isoform. Genomic and RT-PCR analysis revealed four LEAM genes differing by a small variable indel in the coding region. These variations were consistent with the apparent molecular mass of each isoform. Indels, which occurred in repeated domains, did not alter the main properties of LEAM. Structural modelling indicated that the class A α-helix structure, which allows interactions with the mitochondrial inner membrane in the dry state, was preserved in all isoforms, suggesting functionality is maintained. The overall results point out the essential character of LEAM and HSP22 in pea seeds. LEAM variability is discussed in terms of pea breeding history as well as LEA gene evolution mechanisms. [ABSTRACT FROM AUTHOR]

Heat shock proteins (HSPs), well-known in respond to various kinds of stress situations, have been widely studied in Drosophila. However, a few reports related to silkworm bombyx mori. Genetic and non-genetic factors affecting on the expression of some HSPs in heat-treated silkworm were studied at the present paper. The mRNA levels of HSPs were quantified by real-time quantitative RT-PCR method and compared with their expression in the proteome profiles. The results showed up-regulation of two small heat shock proteins (sHSPs), HSP19.9 and HSP20.4 and down-regulation of HSP70 in the fat body, testis and ovary of heat exposed larvae. Higher variation of the sHSPs than HSP70 was observed in the different conditions such as heat exposures and genetic backgrounds. Significant difference in the HSP19.9 expression between two breeds was observed which implied the importance of this gene in the genetic differences. There was significant difference between responses of severe and mild heat shocks after 4 h heat recovery. The HSPs expression in male was significantly higher than that in female silkworm larva for all transcript measurements ( P < 0.001). Comparison of two methods of quantification showed a fair similarity between HSPs expression in the transcriptome and proteome levels. Nistari breed as a naturally thermo-tolerant breed was expressed lower HSPs than a thermo-sensitive breed. [ABSTRACT FROM AUTHOR]

The objective of this study was to investigate at the molecular level the heat shock response in olive by identifying sequences coding for heat shock proteins (HSPs). Young twigs of Olea europaea trees (cv Cellina di Nardo) were subjected to different temperature treatments in order to induce the expression of heat shock genes. In order to identify genes induced by heat treatment, we used a PCR-based approach to amplify specific HS cDNAs. Search for low molecular weight HSP sequences was performed in public domain databases in order to design specific primers based upon multisequence alignments. By this approach, we isolated the first full length cDNA encoding a low-molecular weight HSP from O. europaea. This is a class I low molecular weight HSP of 18.3 kDa, which is highly expressed in young twigs subjected to heat stress. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this study was to clarify the significance of HSP70 and sHSP for thermotolerance in freshwater amphipods. We compared four amphipod species from different freshwater habitats and biogeographical regions (Central Europe vs. Lake Baikal). Test individuals were exposed to thermal stress generated by a water temperature of 25°C. The thermotolerance of the species, determined by median lethal time (LT50), followed in decreasing order by Gmelinoides fasciatus, Echinogammarus berilloni, Gammarus pulex, Eulimnogammarus verrucosus. HSP70 and sHSP base level concentrations for the species were determined at control (i.e. non-stress) conditions. For HSP70, the base levels were positively correlated to the species'' thermotolerances. For sHSP, however, only thermotolerant G. fasciatus showed a high level. Thermal stress at 25°C water temperature caused a deferred onset of HSP70 and sHSP expression followed by a subsequent offset, delineating a unimodal response curve. The time lag to the expression onset of HSP70 was shorter in the thermosensitive species, compared to thermotolerant ones. Conversely, the time span until the maximum level of HSP70 was variable, not showing a dependence on the thermotolerance properties of the species. The peak concentration in G. pulex was distinctly higher than in the other species, whereas E. verrucosus did not develop a well-defined response maximum at all. In sHSP, the temporal pattern of expression was even more variable than in HSP70. However, the thermosensitive species E. verrucosus showed a time lag of expression onset significantly shorter than the other species and thermotolerant G. fasciatus developed the most pronounced response maximum. Basing on these results, the cellular response to thermal stress in amphipods is more consistently reflected by HSP70, compared to sHSP. [Copyright &y& Elsevier]

The role of low-molecular-weight (small) heat shock proteins (sHSPs) in the mechanisms of thermal and toxic resistance in fresh-water organisms was investigated. The four endemic species of Lake Baikal: Gmelinoides fasciatus (Stebb.), Eulimnogammarus cyaneus (Dyb.), E. vittatus (Dyb.), and Ommatogammarus flavus (Dyb.), and Gammarus lacustris Sars, a representative of the Palaearctic fauna, were studied. The effect of the temperature factor was evaluated by exposure of amphipods to temperatures of 20, 25, and 30°C, and the effect of the toxic factor, by exposure to cadmium chloride solutions with concentrations of 50, 10, 5, 0.5, and 0.05 mg/l. All the species showed a common trend of increasing content of sHSPs; species-specific features were observed in the synthesis of the proteins. It was concluded that sHSPs participate in the mechanisms of thermal and toxic resistance in the investigated amphipod species. [ABSTRACT FROM AUTHOR]

Abstract: The small heat shock proteins (sHSP) are characterized by a chaperone activity to prevent irreversible protein denaturation. This study deals with the sHSP Lo18 induced by multiple stresses in Oenococcus oeni, a lactic acid bacterium. Using in situ immunocytochemistry and cellular fractionation experiments, we demonstrated the association of Lo18 with the membrane in O. oeni cells submitted to heat shock. The same result was obtained after exposure of cells to ethanol or benzyl alcohol, agents known to have an influence on membranes. For the different stresses, the protein was located on the periphery of the cell at membrane level and was also found within the cytoplasm. In order to determine if Lo18 could interact with the phospholipids, we used model membranes made of lipids extracted from O. oeni cells. Using fluorescence anisotropy of diphenylhexatriene (DPH) and generalized polarization of Laurdan, we showed that purified Lo18 interacts with these liposomes, and increases the molecular order of the lipid bilayer in these membranes when the temperature reaches 33.8 °C. All these data suggest that Lo18 could be involved in an adaptive response allowing the maintenance of membrane integrity during stress conditions in O. oeni cells. [Copyright &y& Elsevier]

The heat shock response is generally characterized by an immediate, intense, and transient activation of gene expression, resulting in the elevated synthesis of heat shock proteins. We found that light modulates these characteristics of the heat shock response in cyanobacteria. Light accelerated the heat induction of htpG, groESL1, groEL2, and hspA, in Synechocystis sp. PCC 6803. In the dark, heat shock response of all the heat shock genes except hspA was not as intense as in the light and no transient peak was detected within 3 h after heat shock over the time course of the hspA and groESL1 mRNA accumulation. There was an apparent relationship between the enhancement of the heat shock gene transcription in the light and the level of reduced plastoquinone in the photosynthetic electron transport system. Light affected the transcription, but not the stability of the mRNA of heat shock genes, although the stability was quite different, depending on the heat shock gene. Light also enhanced both the accumulation of GroEL under heat stress and the acquired thermo-tolerance. [Copyright &y& Elsevier]

To examine functions of two small heat shock proteins of Escherichia coli , IbpA and IbpB, we constructed His–IbpA and His–IbpB, in which a polyhistidine tag was fused to the N-terminals. Both purified His–IbpA and His–IbpB formed multimers, which have molecular masses of about 2.0–3.0 MDa and consist of about 100–150 subunits. They suppressed the inactivation of several enzymes including citrate synthase and 6-phosphogluconate dehydrogenase by heat, potassium superoxide, hydrogen peroxide and freeze-thawing, but not the inactivation of glyceraldehyde-3-phosphate dehydrogenase by hydrogen peroxide. Both His–IbpA and His–IbpB suppressed enzyme inactivation by various treatments and were also found to be associated with their non-native forms. However, both His–IbpA and His–IbpB were not able to reactivate enzymes inactivated by heat, oxidants or guanidine hydrochloride. When heated to 50 °C, each multimeric form of His–IbpA or His–IbpB was dissociated to form a monomer for His–IbpA, and an oligomer of about one-quarter size for His–IbpB. These structural changes were reversible, as both heated proteins regained the multimeric structures after incubation at 25 °C. However, when exposed to hydrogen peroxide or potassium superoxide, the large multimeric forms of His–IbpA and His–IbpB were maintained. The results suggest that His–IbpA and His–IbpB suppress the inactivation of enzymes and bind non-native proteins to protect their structures from heat and oxidants. [ABSTRACT FROM AUTHOR]

We cloned and sequenced a full-length cDNA encoding the precursor of the mitochondria-located small heat shock protein (MT-sHSP) gene (LeHSP23.8) from tomato (Lycopersicon esculentum). The deduced protein precursor with a calculated molecular weight of 23.8 kDa was predicted to target mitochondria and was classified as a plant MT-sHSP. A single copy of LeHSP23.8 was found in tomato genomic DNA by southern-blot analysis. Northern-blot analysis revealed the heat inducible character of LeHSP23.8 mRNA. The LeHSP23.8 mRNA was hardly detectable at about 36°C but accumulated markedly at 40°C. The molecular chaperone function of LeHSP23.8 was confirmed in vitro. The recombinant LeHSP23.8 was able to enhance the renaturation of chemically denatured citrate synthase (CS). Moreover, the recombinant LeHSP23.8 protected CS from thermal inactivation and also promoted the renaturation of thermally inactivated citrate synthase. [ABSTRACT FROM AUTHOR]

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 (αB-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 the 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., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)

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., (Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.net.)