Cutibacterium acnes as an overseen autoimmunity trigger: Unearthing heat-shock driven molecular mimicry.

Cutibacterium acnes, common resident of the human skin, can establish both commensal and pathogenic relations with the human host; however, long-term consequences of C. acnes-induced inflammation remained un(der)explored. To infer the capacity of triggering autoimmunity in humans via molecular mimicry, a comprehensive immunoinformatics analysis of the experimentally characterized C. acnes proteome was performed. The protocol included homology screening between the C. acnes and the human proteome, and validation of shared specificity regions against the collection of experimentally characterized T-cell epitopes, related to autoimmunity. To obtain highly reliable predictions, the results were subjected to additional cross-validation by a dedicated MHC-restriction analysis, including a docking study of C. acnes mimotopes and human counterparts with the highest degree of sequence similarity to MHCII molecules representing the highest risk for detected autoimmune pathologies. Due to mimicking of highly immunogenic, but also evolutionary conserved autoantigens from the Heat Shock protein family, association between C. acnes and the pathogenesis of highly incident autoimmune diseases: Type 1 Diabetes, Rheumatoid Arthritis, and Juvenile Idiopathic Arthritis, was found. To the best of our knowledge, this study is the first one to provide preliminary information and a mechanistic link on the putative involvement of C. acnes in the pathogenesis of autoimmunity in humans.

GbHSP90 act as a dual functional role regulated in telomere stability in Ginkgo biloba.

The heat shock protein 90 (HSP90) family members are not only widely involved in animal cellular immune response and signal transduction pathway regulation, but also play an important role in plant development and environmental stress response. Here,we identified a HSP90 family member in Ginkgo biloba, designated as GbHSP90, which performs a dual functional role to regulate telomere stability. GbHSP90 was screened by a yeast one-hybrid library using the Ginkgo biloba telomeric DNA (TTTAGGG)5. Fluorescence polarization, surface plasmon resonance(SPR) and EMSA technologyies revealed a specific interaction between GbHSP90 and the double-stranded telomeric DNA via its N-CR region, with no affinity for the single-stranded telomeric DNA or human double-stranded telomeric DNA. Furthermore, yeast two-hybrid system and Split-LUC assay demonstrated that GbHSP90 can interacts with two telomere end-binding proteins:the ginkgo telomerase reverse transcriptase (GbTERT) and the ginkgo Structural Maintenance of Chromosomes protein 1 (GbSMC1). Overexpression of GbHSP90 in human 293 T and HeLa cells increased cell growth rate, the content of telomerase reverse transcriptase (TERT), and promote cell division and inhibit cell apoptosis. Our results indicated GbHSP90 have dually functions: as a telomere-binding protein that binds specifically to double-stranded telomeric DNA and as a molecular chaperone that modulates cell differentiation and apoptosis by binding to telomere protein complexes in Ginkgo biloba. This study contributes to a significantly understanding of the unique telomere complex structure and regulatory mechanisms in Ginkgo biloba, a long-lived tree species.

The rebalancing of the immune system at the maternal-fetal interface ameliorates autism-like behavior in adult offspring.

Maternal immune activation (MIA) is critical for imparting neuropathology and altered behaviors in offspring; however, maternal-fetal immune cell populations have not been thoroughly investigated in MIA-induced autism spectrum disorders (ASDs). Here, we report the single-cell transcriptional landscape of placental cells in both PBS- and poly(I:C)-induced MIA dams. We observed a decrease in regulatory T (Treg) cells but an increase in the M1 macrophage population at the maternal-fetal interface in MIA dams. Based on the Treg-targeting approach, we investigate an immunoregulatory protein, the helminth-derived heat shock protein 90α (Sjp90α), that induces maternal Treg cells and subsequently rescues the autism-like behaviors in adult offspring. Furthermore, in vivo depletion of maternal macrophages attenuates placental inflammatory reaction and reverses behavioral abnormalities in adult offspring. Notably, Sjp90α induces CD4+ T cell differentiation via scavenger receptor A (SR-A) on the macrophage in vitro. Our findings suggest a maternal Treg-targeted approach to alleviate MIA-induced autism-like behavior in adult offspring.

The adaptability of Garut sheep grazing on oil palm and rubber plantations in tropical conditions of Indonesia.

Background and Aim: The productivity of sheep in humid tropical plantation areas relies on their ability to adapt. Oil palm plantations serve as potential grazing lands for livestock. This study aimed to identify Garut sheep adaptations in oil palm and rubber plantations of the Garut district, West Java, Indonesia. Materials and Methods: The total number of sheep used was 103 as the object of this study. Each individual of sheep was used for several different observations, including: Physiological assessment using 24 sheep of various ages, molecular analysis of heat stress using 31 sheep, worm egg count using 59 sheep, and for morphological assessment using 98 sheep. A general linear model was employed to analyze rectal temperature (RT), heart rate (HR), respiratory rate, number of eggs in each gram of sample feces, body weight (BW), body condition score, and morphometric measurements according to age and sex. Forage was compared between oil palm and rubber plantations during the vegetation analysis. Results: RT, HR, and panting frequency were significantly (p < 0.05) affected by the age and sex of the sheep. The mutation was found in the coding region of the HSP70 gene, which is approximately 232 bp long. Fecal eggs were found in 99% of the fecal samples, consisting of 100% Strongyle eggs and 1.75% Moniezia eggs. BW, body condition score, shoulder height, body length, pelvic height, chest circumference, and number of eggs were significantly affected (p < 0.05) by the age and sex of the sheep. The average fresh matter of vegetation under the plantation was 248.69 ± 120.94 g/m2 and 718.15 ± 249.93 g/m2 for oil palm and rubber plantations, respectively. Conclusion: Garut sheep were adapted to oil palm and rubber plantations in the humid tropical region. Plantations are potential sources of sheep grazing and roughage. Further research is needed regarding the consumption of forages in oil palm and rubber plantations.

Development and Preclinical Evaluation of 18F-Labeled PEGylated Sansalvamide A Decapeptide for Noninvasive Evaluation of Hsp90 Status in Pancreas Cancer.

Heat shock protein 90 (Hsp90) is a promising target for cancer therapy and imaging. Accurate detection of Hsp90 levels in tumors via noninvasive PET imaging might be beneficial for management. To achieve this, the precursor compound Dimer-Sansalvamide A (Dimer-San A) was PEGylated and modified by conjugating it with the bifunctional chelator 1,4,7-triazacyclononane-1,4,7-triacetic acid (NOTA). The 18F-labeled PEGylated Dimer-SanA decapeptide (18F-PEGylated San A) was completed within 30 min using a two-step process. In vitro stability and specificity were assessed, including competition studies with the Hsp90 inhibitor 17-allylamino-17-demethoxygeldanamycin (17-AAG). MicroPET imaging was performed on PL45 tumor-bearing mice to evaluate probe accumulation and tumor-to-muscle ratios. Biodistribution studies determined the route of excretion. The probe resulted in a radiochemical yield of 23.11% with a purity exceeding 95%. In vitro, 18F-PEGylated San A exhibited high stability and selectively accumulated in Hsp90-positive PL45 cells, with binding effectively blocked by the Hsp90 inhibitor 17AAG, confirming its specificity. MicroPET imaging of PL45 tumor-bearing mice showed significant probe accumulation in tumor tissues at 1 and 2 h postinjection (4.06 ± 0.30 and 3.72 ± 0.61%ID/g, respectively), with optimal tumor-to-muscle ratios observed at 2 h postinjection (6.09 ± 1.92). While 18F-PEGylated San A demonstrates enhanced water solubility, as indicated by increased kidney uptake relative to liver accumulation. The study successfully incorporated PEG units to create the novel probe 18F-PEGylated San A targeting to Hsp90 without affecting its targeting capability, aimed at improving the pharmacokinetics and PET imaging of Hsp90 expression noninvasively.

Thermal Stress and Nuclear Transport.

Nuclear transport is the basis for the biological reaction of eukaryotic cells, as it is essential to coordinate nuclear and cytoplasmic events separated by nuclear envelope. Although we currently understand the basic molecular mechanisms of nuclear transport in detail, many unexplored areas remain. For example, it is believed that the regulations and biological functions of the nuclear transport receptors (NTRs) highlights the significance of the transport pathways in physiological contexts. However, physiological significance of multiple parallel transport pathways consisting of more than 20 NTRs is still poorly understood, because our knowledge of each pathway, regarding their substrate information or how they are differently regulated, is still limited. In this report, we describe studies showing how nuclear transport systems in general are affected by temperature rises, namely, thermal stress or heat stress. We will then focus on Importin α family members and unique transport factor Hikeshi, because these two NTRs are affected in heat stress. Our present review will provide an additional view to point out the importance of diversity of the nuclear transport pathways in eukaryotic cells.

HSPA12A promotes c-Myc lactylation-mediated proliferation of tubular epithelial cells to facilitate renal functional recovery from kidney ischemia/reperfusion injury.

Proliferation of renal tubular epithelial cells (TEC) is essential for restoring tubular integrity and thereby to support renal functional recovery from kidney ischemia/reperfusion (KI/R) injury. Activation of transcriptional factor c-Myc promotes TEC proliferation following KI/R; however, the mechanism regarding c-Myc activation in TEC is incompletely known. Heat shock protein A12A (HSPA12A) is an atypic member of HSP70 family. In this study, we found that KI/R decreased HSPA12A expression in mouse kidneys and TEC, while ablation of HSPA12A in mice impaired TEC proliferation and renal functional recovery following KI/R. Gain-of-functional studies demonstrated that HSPA12A promoted TEC proliferation upon hypoxia/reoxygenation (H/R) through directly interacting with c-Myc and enhancing its nuclear localization to upregulate expression of its target genes related to TEC proliferation. Notably, c-Myc was lactylated in TEC after H/R, and this lactylation was enhanced by HSPA12A overexpression. Importantly, inhibition of c-Myc lactylation attenuated the HSPA12A-induced increases of c-Myc nuclear localization, proliferation-related gene expression, and TEC proliferation. Further experiments revealed that HSPA12A promoted c-Myc lactylation via increasing the glycolysis-derived lactate generation in a Hif1α-dependent manner. The results unraveled a role of HSPA12A in promoting TEC proliferation and facilitating renal recovery following KI/R, and this role of HSPA12A was achieved through increasing lactylation-mediated c-Myc activation. Therefore, targeting HSPA12A in TEC might be a viable strategy to promote renal functional recovery from KI/R injury in patients.

SUMOylation of protein phosphatase 5 regulates phosphatase activity and substrate release.

The serine/threonine protein phosphatase 5 (PP5) regulates hormone and stress-induced signaling networks. Unlike other phosphoprotein phosphatases, PP5 contains both regulatory and catalytic domains and is further regulated through post-translational modifications (PTMs). Here we identify that SUMOylation of K430 in the catalytic domain of PP5 regulates phosphatase activity. Additionally, phosphorylation of PP5-T362 is pre-requisite for SUMOylation, suggesting the ordered addition of PTMs regulates PP5 function in cells. Using the glucocorticoid receptor, a well known substrate for PP5, we demonstrate that SUMOylation results in substrate release from PP5. We harness this information to create a non-SUMOylatable K430R mutant as a 'substrate trap' and globally identified novel PP5 substrate candidates. Lastly, we generated a consensus dephosphorylation motif using known substrates, and verified its presence in the new candidate substrates. This study unravels the impact of cross talk of SUMOylation and phosphorylation on PP5 phosphatase activity and substrate release in cells.

Enzymatic Hydrolysis of Resorcylic Acid Lactones by an Aeromicrobium sp.

Zearalenone and radicicol are resorcylic acid lactones produced by numerous plant pathogenic fungi. Zearalenone is a non-steroidal estrogen mimic that can cause serious reproductive issues in livestock that consume contaminated feed. Radicicol is a potent inhibitor of the molecular chaperone Hsp90, which, in plants, has an important role in coordinating the host's immune response during infection. Here, we describe the identification and characterization of a soil-borne strain of the Gram-positive bacterium Aeromicrobium sp. capable of hydrolyzing the macrolide ring of resorcylic acid lactones, including zearalenone and radicicol. Proteomic analysis of biochemically enriched fractions from the isolated and cultured bacterium identified an α/ß-hydrolase responsible for this activity. A recombinantly expressed and purified form of the hydrolase (termed RALH) was active against both zearalenone and radicicol. Interpretation of high-resolution mass spectrometry and NMR data confirmed the structures of the enzymatic products as the previously reported non-toxic metabolite hydrolyzed zearalenone and hydrolyzed radicicol. Hydrolyzed radicicol was demonstrated to no longer inhibit the ATPase activity of the Saccharomyces cerevisiae Hsp90 homolog in vitro. Enzymatic degradation of resorcylic acid lactones will enable insight into their biological functions.

O-GlcNAc modification of HSP27 alters its protein interactions and promotes refolding of proteins through the BAG3/HSP70 co-chaperone.

Almost all types of cellular stress induce post-translational O-GlcNAc modifications of proteins, and this increase promotes cell survival. We previously demonstrated that O-GlcNAc on certain small heat shock proteins (sHSPs), including HSP27, directly increases their chaperone activity as one potential protective mechanism. Here, we furthered our use of synthetic proteins to prepare biotinylated sHSPs and show that O-GlcNAc modification of HSP27 also changes how it interacts within the sHSP system and the broader HSP network. Specifically, we show that O-GlcNAc modified HSP27 binds more strongly to the co-chaperone protein BAG3, which then promotes refolding of a model substrate by HSP70. We use proteomics to identify other potential HSP27 interactions that are changed by O-GlcNAc, including one that we confirm with another sHSP, αB-crystallin. These findings add additional evidence for O-GlcNAc as a switch for regulating protein-protein interactions and for modifications of chaperones as one mechanism by which O-GlcNAc protects against protein aggregation.

The protective effects of esculetin against Doxorubicin-Induced hepatotoxicity in rats: Insights into the modulation of Caspase, FOXOs, and heat shock protein pathways.

Doxorubicin (DOX) is an anthracycline antibiotic widely employed to treat carcinoma. Nevertheless, severe cardiotoxic side effects restrict its clinical use. Esculetin, a natural flavonoid, is found abundantly in plants. This study evaluated the protective effects of esculetin against DOX-induced hepatotoxicity in rat livers. Forty-eight rats were randomly divided into six groups with eight rats in each group: control (I), DOX (II), esculetin (III, 50 mg/kg), esculetin (IV, 100 mg/kg), DOX+esculetin 50 (V, DOX+esculetin 50 mg/kg), and DOX+esculetin 100 (VI, DOX+esculetin 100 mg/kg). The administration of esculetin effectively mitigated alterations in the measured biochemical parameters induced by DOX. Gene expression analyses demonstrated that esculetin treatment significantly reduced the DOX-induced expression of Foxo1, Hspa1a, Hsp4a, Hsp5a, Casp3, and Casp9 while increasing the DOX-induced expression of Foxo3. These findings suggest that esculetin, with its antioxidant and anti-inflammatory effects, might be a therapeutic option for protecting against DOX-induced hepatotoxicity.

Safe concentration, unsafe effects: Impact of BPA on antioxidant function in the hepatopancreas and ovarian gene expression in oriental river prawns (Macrobrachium nipponense).

This study investigated the effects of Bisphenol A (BPA), a common endocrine-disrupting chemical, on the antioxidant enzyme activities in the hepatopancreas and the expression of genes related to ovarian development in oriental river prawns (Macrobrachium nipponense). The 24hLC50 and 48hLC50 values for BPA were 80.59 mg/L and 63.90 mg/L, respectively, with a safe concentration of 12.06 mg/L. Prawns were exposed to low (4.85 mg/L), safe (12.06 mg/L), and high (30.00 mg/L) concentrations of BPA for 10 days to measure enzyme activities, and for 20 days followed by 7 days in BPA-free water to measure gene expression. Short-term exposure (12 h, 1d, 3d) to low concentration BPA did not significantly affect superoxide dismutase (SOD) activity in the hepatopancreas (P > 0.05), but long-term exposure (6d, 10d) significantly reduced SOD activity (P < 0.05). Catalase (CAT) activity showed no significant changes throughout the low concentration exposure period (P > 0.05). At safe and high concentrations, SOD and CAT activities significantly decreased after 12 h of exposure (P < 0.05). BPA affected heat shock protein 90 (HSP90) expression in the ovary, with low concentration BPA significantly upregulating HSP90 after 1 day (P < 0.05), but returning to normal levels after 10 and 20 days. At the safe concentration, HSP90 was significantly upregulated at all three sampling points (1d, 10d, 20d) (P < 0.05), while high concentration exposure led to significant upregulation only on day 10 (P < 0.05). Low concentration BPA had no significant effect on Cathepsin B (CB) and Cathepsin L (CL) gene expression in the ovaries (P > 0.05). However, safe concentration exposure promoted CB expression on days 1, 10, and 20 (P < 0.05), while high concentration exposure significantly increased CB expression on day 1 (P < 0.05), with levels returning to normal on days 10 and 20. CL expression significantly increased after 20 days of exposure to both safe and high concentrations (P < 0.05). Gene expression levels in the ovaries returned to normal after transfer to BPA-free water, with HSP90 and CB normalizing by day 1, and CL by day 7. These results indicate that even safe concentrations of BPA impose stress on the hepatopancreas and increase the expression of HSP90, CB, and CL genes in the ovaries, affecting ovarian development. And, these effects are reversible within a certain period after the removal of BPA.

Unveiling the impact of SUMOylation at K298 site of heat shock factor 1 on glioblastoma malignant progression.

BACKGROUND: Glioblastoma (GBM) poses a significant medical challenge due to its aggressive nature and poor prognosis. Mitochondrial unfolded protein response (UPRmt) and the heat shock factor 1 (HSF1) pathway play crucial roles in GBM pathogenesis. Post-translational modifications, such as SUMOylation, regulate the mechanism of action of HSF1 and may influence the progression of GBM. Understanding the interplay between SUMOylation-modified HSF1 and GBM pathophysiology is essential for developing targeted therapies. METHODS: We conducted a comprehensive investigation using cellular, molecular, and in vivo techniques. Cell culture experiments involved establishing stable cell lines, protein extraction, Western blotting, co-immunoprecipitation, and immunofluorescence analysis. Mass spectrometry was utilized for protein interaction studies. Computational modeling techniques were employed for protein structure analysis. Plasmid construction and lentiviral transfection facilitated the manipulation of HSF1 SUMOylation. In vivo studies employed xenograft models for tumor growth assessment. RESULTS: Our research findings indicate that HSF1 primarily undergoes SUMOylation at the lysine residue K298, enhancing its nuclear translocation, stability, and downstream heat shock protein expression, while having no effect on its trimer conformation. SUMOylated HSF1 promoted the UPRmt pathway, leading to increased GBM cell proliferation, migration, invasion, and reduced apoptosis. In vivo studies have confirmed that SUMOylation of HSF1 enhances its oncogenic effect in promoting tumor growth in GBM xenograft models. CONCLUSION: This study elucidates the significance of SUMOylation modification of HSF1 in driving GBM progression. Targeting SUMOylated HSF1 may offer a novel therapeutic approach for GBM treatment. Further investigation into the specific molecular mechanisms influenced by SUMOylated HSF1 is warranted for the development of effective targeted therapies to improve outcomes for GBM patients.

Investigating the immunological activity of the Hsp70-P113 fusion protein for Mycoplasma ovipneumoniae detection: a groundbreaking study.

BACKGROUND: Mycoplasmal pneumonia of sheep and goats (MPSG) is an important infectious disease that threatens sheep and goat production worldwide, and Mycoplasma ovipneumoniae (Movi) is one of the major aetiological agents causing MPSG. The aim of this study was to investigate the immunological activity of the Hsp70‒P113 fusion protein derived from Movi and to develop a serological assay for the detection of Movi. METHODS: This study involved codon optimization of the dominant antigenic regions of Movi heat shock protein 70 (Hsp70) and adhesin P113. Afterwards, the optimized sequences were inserted into the prokaryotic expression vector pET-30a( +) through tandem linking with the aid of a linker. Once a positive recombinant plasmid (pET-30a-rHsp70-P113) was successfully generated, the expression conditions were further refined. The resulting double gene fusion target protein (rHsp70‒P113) was subsequently purified using ProteinIso® Ni-NTA resin, and the reactivity of the protein was confirmed via SDS‒PAGE and Western blot analysis. An indirect enzyme-linked immunosorbent assay (i-ELISA) technique was developed to detect Movi utilizing the fusion protein as the coating antigen. The specificity, sensitivity, and reproducibility of all methods were assessed after each reaction parameter was optimized. RESULTS: The resulting rHsp70-P113 protein had a molecular weight of approximately 51 kDa and was predominantly expressed in the supernatant. Western blot analysis demonstrated its favourable reactivity. The optimal parameters for the i-ELISA technique were as follows: the rHsp70-P113 protein was encapsulated at a concentration of 5 µg/mL; the serum was diluted at a ratio of 1:50; the HRP-labelled donkey anti-goat IgG was diluted at a ratio of 1:6,000. The results of the cross-reactivity assays revealed that the i-ELISA was not cross-reactive with other goat-positive sera against Mycoplasma mycodies subsp. capri (Mmc), Mycoplasma capricolum subsp. capripneumoniae (Mccp), Mycoplasma arginini (Marg), orf virus (ORFV) or enzootic nasal tumour virus of goats (ENTV-2). The sensitivity of this method is high, with a maximum dilution of up to 1:640. The results of the intra- and inter-batch replication tests revealed that the coefficients of variation were both less than 10%, indicating excellent reproducibility. The analysis of 108 clinical serum samples via i-ELISA and indirect haemagglutination techniques yielded significant findings. Among these samples, 43 displayed positive results, whereas 65 presented negative results, resulting in a positivity rate of 39.8% for the i-ELISA method. In contrast, the indirect haemagglutination technique identified 20 positive samples and 88 negative samples, resulting in a positivity rate of 18.5%. Moreover, a comparison between the two methods revealed a conformity rate of 78.7%. CONCLUSION: The results obtained in this study lay the groundwork for advancements in the use of an Movi antibody detection kit, epidemiological inquiry, and subunit vaccines.

Isolation and identification of non-tuberculous mycobacteria from aquarium fish in Ilam, Iran.

Non-tuberculous mycobacteria (NTM) are among the most important pathogens in wild, captive, marine, and freshwater fish species. So, it is important to consider fish as the primary source of infection for aquarium fish and humans. The present study analyzed the occurrence of NTM in aquarium fish in Ilam, west of Iran. In total, 50 samples of infected fish were collected from different aquariums. Following initial sample processing, sediment of each sample was inoculated into Lowenstein-Jensen and Herrold egg media. The positive colonies were investigated with, growth rate, pigmentation, colony morphology, niacin accumulation, nitrate reduction, catalase activity, urease activity, and arylsulfatase activity. Also, molecular identification was carried out by sequencing of heat shock protein 65 kD gene (hsp65) sequence analysis. According to our results, NTM were isolated from 13 samples (26%), comprising 6 (46.2%) rapid growing, and 7 (53.8%) slow growing mycobacteria. In addition, Mycobacterium marinum was the most common NTM isolated in ornamental fish, which is potentially dangerous for both fish and humans. In conclusion, the current study indicates that ornamental fish play a significant role as a source of NTM.

Allosteric site identification, virtual screening and discovery of a sulfonamide Hsp110-STAT3 interaction inhibitor for the treatment of hypoxic pulmonary arterial hypertension.

Pulmonary arterial hypertension (PAH) is a severe pulmonary vascular disorder marked by vascular remodeling, which is linked to the malignant phenotypes of pulmonary vascular cells. The prevailing therapeutic approaches for PAH tend to neglect the potential role of vascular remodeling, leading to the clinical prognosis remains poor. Previously, we first demonstrated that heat shock protein (Hsp110) was significantly activated to boost Hsp110-STAT3 interaction, which resulted in abnormal proliferation and migration of human pulmonary arterial endothelial cells (HPAECs) under hypoxia. In the present study, we initially postulated the allosteric site of Hsp110, performed a virtual screening and biological evaluation studies to discover novel Hsp110-STAT3 interaction inhibitors. Here, we identified compound 29 (AN-329/43448068) as the effective inhibitor of HPAECs proliferation and the Hsp110-STAT3 association with good druggability. In vitro, 29 significantly impeded the chaperone function of Hsp110 and the malignant phenotypes of HPAECs. In vivo, 29 remarkably attenuated pulmonary vascular remodeling and right ventricular hypertrophy in hypoxia-induced PAH rats (i.g). Altogether, our data support the conclusion that it not only provides a novel lead compound but also presents a promising approach for subsequent inhibitor development targeting Hsp110-STAT3 interaction.

Potential use of HSP70 as an indicator of heat stress in dairy cows - a review.

Heat stress (HS) poses significant challenges to the dairy industry, resulting in reduced milk production, impaired reproductive performance, and compromised animal welfare. Therefore, understanding the molecular mechanisms underlying cellular responses to HS is crucial for developing effective strategies to mitigate its adverse effects. Heat shock protein 70 (HSP70) has emerged as a potential player involved in cellular thermotolerance in dairy cows. This review provides a comprehensive overview of the role of HSP70 as a molecular chaperone in cellular thermotolerance in dairy cows under HS. HSP70 facilitates proper protein folding and prevents the aggregation of denatured proteins. By binding to misfolded proteins, it helps maintain protein homeostasis and prevents the accumulation of damaged proteins during HS. Additionally, HSP70 interacts with various regulatory proteins and signaling pathways, contributing to the cellular adaptive response to HS. The upregulation of HSP70 expression in response to HS is regulated by a complex network involving heat-shock factors (HSFs), heat-shock element-binding proteins, and HSF co-chaperones. Therefore, HSP70 holds the potential to be a useful indicator of tissue stress due to its role in maintaining cellular balance, and as it is released both inside and outside cells in response to stress. Traditional methods of measuring HSP70 in blood samples are labor-intensive, and with the process being potentially stressful for the animals and may subsequently affect the results. Therefore, measuring HSP expression in cow's milk has shown promise as an easy, non-invasive, and accurate way to detect HS in dairy cows. Monitoring HSP70 levels in milk can be applied as a supplementary approach to identify HS or HS resistance of individual cows, selection of suitable animals and to guide targeted management strategies. However, despite the potential advantages of using HSP70 as a biomarker for monitoring HS on dairy cows, challenges remain in standardizing measurement protocols, establishing species-specific reference ranges, addressing inter-individual variations, and determining the specificity of changes in HSP70 due to HS. Future research should focus on developing non-invasive techniques for HSP70 detection, with consideration of climatic conditions, and unravelling the molecular interactions and regulatory networks involving HSP70.

Two new oligomers of E. coli small heat-shock protein IbpB identified under heat stress exhibit maximum holding chaperone activity.

Escherichia coli small heat-shock protein IbpB (MW: 16 KDa) has holding chaperone activity and is present in cells at 30 °C as two large oligomers of MW 2.0-3.0 MDa and 600-700 KDa. We report here about the presence of two additional oligomers of MW around 400 and 130 KDa in cells under heat-stress at 50 °C. These two smaller oligomers possess the most chaperone activity, as observed from the extent of inhibition of inactivation and aggregation separately, of L-Lactate dehydrogenase in the presence of the individual oligomers at 52 and 60 °C, respectively. It is suggested here that the two larger oligomers act as poorly active storage forms, which under heat stress dissociate partially into smaller oligomers with high holdase activity.

Heat shock proteins as hallmarks of cancer: insights from molecular mechanisms to therapeutic strategies.

Heat shock proteins are essential molecular chaperones that play crucial roles in stabilizing protein structures, facilitating the repair or degradation of damaged proteins, and maintaining proteostasis and cellular functions. Extensive research has demonstrated that heat shock proteins are highly expressed in cancers and closely associated with tumorigenesis and progression. The "Hallmarks of Cancer" are the core features of cancer biology that collectively define a series of functional characteristics acquired by cells as they transition from a normal state to a state of tumor growth, including sustained proliferative signaling, evasion of growth suppressors, resistance to cell death, enabled replicative immortality, the induction of angiogenesis, and the activation of invasion and metastasis. The pivotal roles of heat shock proteins in modulating the hallmarks of cancer through the activation or inhibition of various signaling pathways has been well documented. Therefore, this review provides an overview of the roles of heat shock proteins in vital biological processes from the perspective of the hallmarks of cancer and summarizes the small-molecule inhibitors that target heat shock proteins to regulate various cancer hallmarks. Moreover, we further discuss combination therapy strategies involving heat shock proteins and promising dual-target inhibitors to highlight the potential of targeting heat shock proteins for cancer treatment. In summary, this review highlights how targeting heat shock proteins could regulate the hallmarks of cancer, which will provide valuable information to better elucidate and understand the roles of heat shock proteins in oncology and the mechanisms of cancer occurrence and development and aid in the development of more efficacious and less toxic novel anticancer agents.

EP4 receptor agonist CAY10598 upregulates ROS-dependent Hsp90 cleavage in colorectal cancer cells.

Prostaglandin E2 (PGE2) interacts with four specific G protein-coupled receptors, namely EP1, EP2, EP3, and EP4, playing a pivotal role in determining the fate of cells. Our previous findings highlighted that stimulating the EP4 receptor with its agonist, CAY10598, triggers apoptosis in colon cancer HCT116 cells via the production of reactive oxygen species (ROS). This process also reduces the phosphorylation of the oncogenic protein JAK2 and leads to its degradation in these cells. In this study, our goal was to explore the pathways through which CAY10598 leads to JAK2 degradation. We focused on Hsp90, a heat shock protein family member known for its role as a molecular chaperone maintaining the stability of several key proteins including EGFR, MET, Akt, and JAK2. Our results show that CAY10598 decreases the levels of client proteins of Hsp90 in HCT116 cells, an effect reversible by pretreatment with the ROS scavenger N-acetyl cysteine (NAC) or the proteasome inhibitor MG132, indicating that the degradation is likely driven by ROS. Furthermore, we observed that CAY10598 cleaves both α and ß isoforms of Hsp90, the process inhibited by NAC. Inhibition of EP4 with the antagonist GW627368x not only prevented the degradation of Hsp90 client proteins but also the cleavage of Hsp90 itself in CAY10598-treated HCT116 cells. Additionally, CAY10598 suppressed the growth of HCT116 cells implanted in mice. Our findings reveal that CAY10598 induces apoptosis in cancer cells by a novel mechanism involving the ROS-dependent cleavage of Hsp90, thereby inhibiting the function of crucial Hsp90 client proteins.