Search Results (119)

Heat shock proteins 70 (HSP 70) are molecular chaperonins ubiquitously expressed in both prokaryotes and eukaryotes and are involved in the modulation and exacerbation of the immune response. The present study aimed to assess the immunohistochemical expression of HSP70 and apoptosis markers, such as TUNEL and Caspase-3, in 17 cases of cutaneous lupus erythematosus (CLE) in dogs to determine whether HSP70 expression correlates with cell apoptosis and to highlight possible involvement of HSP70 in the pathogenesis of CLE. The results revealed positive HSP70 expression in epidermal and inflammatory cells across all cases, with a significant correlation between HSP70 expression score and TUNEL-positive cells but not with Caspase-3-positive cells. This correlation could indicate a possible role for HSP70 in cell death via a caspase-independent apoptotic mechanism or other programmed cell death mechanisms, such as pyroptosis or necroptosis. The precise mechanisms by which HSP70 acts in this specific pathological context remain incompletely understood, but the results of this study provide important information for future investigations into autoimmune skin disease in dogs. Full article

For a protein to perform its biological functions, it must adopt a specific three-dimensional conformation. In addition, many proteins require the assistance of other protein complexes known as chaperonins to fold —i.e., to acquire such a specific conformation—, although the exact mechanisms whereby the chaperonins act and assist the folding process have not been completely determined. In this work, we characterize the physical environment at the interior of the chaperonin HSP60/HSP10 via Molecular Dynamics Simulations. We found that, inside the cavity of the chaperonin (within a region covering much of the cavity’s volume), the long-range electrostatic potential presents a structured pattern that, except for small fluctuations, does not change in time. The electrostatic potential generates an electric field that can be modeled, as a first approximation, as constant and unidirectional $(\mathit{E}/\left(\mathrm{V}·{\AA }^{-1}\right)\approx -0.0054\widehat{𝚤}+0.010\widehat{\mathit{𝚥}}-0.162\widehat{k}$, here the chaperonin’s main axis is aligned along $\widehat{k})$, which can produce large deformations in the structure of a heated protein (Rhodanese); the long-range approximated $\mathit{E}\left(\mathit{r}\right)$ can in fact unfold the Rhodanese, when applied as an external field. Finally, we discuss the possible implications of such an electric field for the protein folding problem, within the context of proteins whose folding is assisted by chaperones. The existence and effects of the electric field are consistent with several theories and experimental observations related to the protein folding problem, in particular with the foldon view. Full article

Soybeans are highly susceptible to drought stress, which significantly impairs their growth and yield. Silicon (Si) supplementation has emerged as a promising strategy to mitigate drought-induced damage in plants. We investigated changes in the physiological and chloroplast proteomes in soybeans under drought stress, both with and without Si supplementation. Soybean plants were grown under controlled conditions and subjected to drought stress. The treatments included Si application (sodium silicate), sodium chloride control, and water control. Chloroplast proteins were extracted from control and Si-treated plants and analyzed using two-dimensional gel electrophoresis and mass spectrometry. Plants treated with Si showed improved drought tolerance, exhibiting reduced leaf rolling and wilting, while the control plants experienced significant wilting under drought conditions. Photosynthetic performance, measured by quantum efficiency of photosystem II and chlorophyll content, was better maintained in Si-supplemented plants under drought. However, stomatal conductance and transpiration were similarly reduced across all drought treatments. We detected 15 Si-responsive protein spots corresponding to 13 unique chloroplast proteins that were differentially expressed in response to Si supplementation. These identified proteins include those involved in photosynthesis, such as Rubisco activase isoforms, oxygen-evolving enhancer proteins, and PsbP domain-containing protein, as well as stress response proteins like dehydrin and 20 kDa chaperonin. Si treatment upregulated Rubisco activase isoforms, oxygen-evolving enhancer proteins, PsbP domain-containing protein, and 20 kDa chaperonin, which are typically reduced under drought. Si treatment maintained a higher glutamine synthetase level under drought stress. Gene ontology and KEGG pathway analyses revealed that Si-modulated proteins are associated with photosynthesis, energy metabolism, and nitrogen metabolism under drought stress. Our findings demonstrate that Si supplementation alleviates drought stress in soybean by preserving chloroplast function and enhancing the expression of photosynthetic proteins and enzymes, as well as key stress-responsive proteins. This research provides insights into the molecular mechanisms of Si-induced drought tolerance in soybeans and highlights potential targets for developing drought-resilient soybean cultivars. Full article

The heat shock protein 60 (Hsp60) is a highly conserved molecular chaperonin belonging to the chaperone system, a complex network that maintains proteostasis and regulates numerous cellular processes beyond protein folding. Initially described as a mitochondrial protein essential for the folding of newly imported polypeptides, Hsp60 is now recognized as a multifunctional molecule. Its expression, localization, and post-translational modifications dynamically influence cell fate and tissue homeostasis. Alterations in Hsp60 quantity, structure, or distribution underlie a heterogeneous group of disorders known as chaperonopathies, which may occur “by defect,” “by excess,” or “by mistake” (also called “by collaborationism”). Genetic Hsp60’s chaperonopathies are associated with rare neurodegenerative and cardiovascular diseases, whereas acquired forms contribute to widespread conditions, including autoimmune, inflammatory, and malignant pathologies. This review provides a comprehensive overview of Hsp60 biology across human systems, emphasizing its structural plasticity, context-dependent functions, and dual role in health as both a biomarker and a therapeutic target. The emerging paradigm of chaperonotherapy, encompassing positive strategies to restore protective chaperones and negative strategies to inhibit pathogenic ones, highlights the translational potential of targeting Hsp60. Understanding the molecular mechanisms governing its activity will be essential for developing precision medicine approaches aimed at modulating the chaperone system in human disease. Full article

Although calpain-5/CAPN5 is widely expressed in mammals, little is known regarding its functions. Pathogenic mutations of CAPN5 are causal for a devastating autoimmune eye disease, neovascular inflammatory vitreoretinopathy (NIV). To provide insight into both the physiological and pathological roles of CAPN5, it is essential to identify candidate interaction partners and possible substrates. Human SH-SY5Y neuroblastoma cells, transfected with full-length catalytically dead (Cys81Ala) CAPN5-3×FLAG, were used for anti-FLAG co-immunoprecipitation (co-IP) and quantitative proteomics using Sequential Window Acquisition of all THeoretical mass spectra (SWATH-MS). Fifty-one proteins were enriched at least four-fold, p < 0.01, relative to cells transfected with an empty FLAG vector. A high proportion (24/51) of candidate CAPN5 interaction partners are associated with protein quality control, including components of the chaperonin, chaperone, and ubiquitin–proteasome systems. Additional candidate interactors include tubulins, kinases, phosphatases, G proteins, and mitochondrial proteins. CAPN5 interactions for 14 of the candidate proteins were confirmed by co-IP and immunoblotting. Of these 14 proteins, 11 exhibited in vitro calcium-induced proteolysis following co-IP with WT CAPN5-3×FLAG. Impaired calcium-induced proteolysis of co-IP proteins was observed for the pathogenic CAPN5 variants R243L and R289W. Further studies are needed to validate the association of candidate CAPN5 interactors with proteins and complexes suggested by the SWATH-MS and co-IP results, and the possible role of CAPN5 within such complexes. The possible involvement of CAPN5 in protein quality control is relevant to NIV, as defects in protein quality control have been implicated in inherited retinal disorders. Proteomic data are available via ProteomeXchange with identifier PXD068008. Full article

Background/Objectives. Antibiotic resistance is an escalating global health concern, highlighting the need for innovative antibacterial strategies beyond traditional drugs. GroEL, a highly conserved bacterial chaperonin essential for protein folding and stress tolerance, represents a promising but underexplored therapeutic target. This study aimed to identify short peptides capable of binding GroEL monomers and potentially altering their function, with the long-term goal of disrupting bacterial survival mechanisms. Methods. A phage display screening of a 12-mer peptide library was performed against purified GroEL monomers, yielding five candidate peptides (G1–G5). Their interactions with GroEL were analyzed through molecular docking and molecular dynamics simulations using three-dimensional GroEL structures (1MNF, 1XCK, 8S32). Stability of binding and interaction profiles were assessed through molecular dynamics-based analyses and MM/GBSA free energy calculations. Results. Peptides G4 and G5 displayed the most stable and energetically favorable interactions, with G4–8S32 showing the strongest binding (−116.68 kcal/mol). These peptides localized near inter-subunit interfaces, suggesting potential interference with GroEL oligomerization or allosteric transitions, which are critical for its biological function. Conclusions. Our findings demonstrate that short peptides can stably bind GroEL and potentially modulate its activity. Peptides G4 and G5 represent at our knowledge the first promising scaffolds for developing a novel class of peptide-based antibacterial agents targeting conserved chaperonin systems. This work introduces a new avenue that warrants further experimental validation. Full article

Glioblastoma (GBM) is characterized by its unique molecular features, such as self-renewal and tumorigenicity of glioma stem cells that promote resistance, largely resulting in treatment failure. Among the molecular alterations significant to GBM biology and treatment, mutations in isocitrate dehydrogenase (IDH) have assumed particular relevance. IDH-mutant and IDH-wild-type tumors exhibit significantly different metabolic characteristics, clinical behavior, and therapeutic sensitivities, making IDH status a critical determinant in determining prognosis and treatment strategies for GBM. In the context of cancer, chaperones were shown to promote tumor progression by supporting malignant cells over healthy ones. While heat shock proteins (HSPs) have long been implicated in the molecular mechanisms of tumor phenotype progression, recent attention has turned to CCT (chaperonin containing TCP1), orchestrating proteostasis. The chaperonin CCT is being explored as a diagnostic and therapeutic target in many cancers, including GBM, owing to its involvement in key oncogenic signaling pathways such as Wnt, VEGF, EGFR, and PI3K/AKT/mTOR. However, its role in the GBM-tricarboxylic acid (TCA) cycle cascade is still not well understood. Therefore, the present review highlights the potential role of the CCT complex in regulating hypoxia-inducible factor (HIF) activation by modulating enzymes responsive to metabolites derived from glucose metabolism and the TCA cycle in a manner dependent on oxygen availability and IDH mutation status. Full article

Protein–protein docking is a cornerstone of computational structural biology, yet its reliability for large, multimeric assemblies remains uncertain. Standard workflows typically include geometry optimization or molecular dynamics equilibration to relieve local strains and improve input quality, but the extent to which these preparatory steps alter docking outcomes has not been systematically evaluated. Here, we address this question using the mitochondrial chaperonin Hsp60, a dynamic double-ring complex essential for protein folding, and MIX, a kinetoplastid-specific protein with unresolved function, as a stress test system. By comparing docking predictions across minimized, equilibrated, and ensemble-refined structures of Hsp60 in three conformational states (apo, ATP-bound, and ATP–Hsp10), we show that structural relaxation profoundly reshapes the docking landscape. Minimization alone often yielded favorable scores but localized binding, while longer MD trajectories exposed alternative sites, including central cavity, equatorial ATP pocket, and apical domain, each consistent with distinct regulatory hypotheses. These findings reveal that docking outcomes are highly sensitive to receptor preparation, especially in complexes undergoing large conformational transitions. More broadly, our study highlights an underappreciated vulnerability of docking pipelines and calls for ensemble-based and dynamics-aware approaches when predicting interactions in large biomolecular machines. Full article

Molecular chaperones are crucial for maintaining protein homeostasis by assisting in the proper folding, stabilization, and function of proteins. Among them, Heat shock protein 90 (Hsp90), represents a highly conserved protein family of molecular chaperones that plays an essential role in diverse biological processes and is fundamental to cellular health and survival. As a highly abundant molecular chaperone, Hsp90 comprises 1–2% of cellular proteins, increasing to 4–6% under stress conditions. It interacts with client proteins, assisting them in proper folding and stability. Unlike classical chaperonins, Hsp90 operates through a highly regulated, ATP-dependent cycle that involves multiple co-chaperones. This process allows Hsp90 to selectively engage with numerous client proteins, including signaling proteins, kinases, hormone receptors, and transcription factors. Recent discoveries have revealed its involvement in processes beyond protein folding, demonstrating its role in diverse cellular functions such as epigenetic regulation, immune signaling, and oncogenic transformation. This current review highlighted the specific characteristics of cytoplasmic and endoplasmic reticulum (ER) as well as mitochondrial paralogs and functions, focusing on its contribution to buffering genetic variation, facilitating oncogene addiction, and modulating disease phenotypes in conditions such as cancer, neurodegeneration, cardiovascular diseases (CVD), and diabetes. We also discuss the therapeutic potential of targeting Hsp90 and its co-chaperones, outlining the challenges and prospects in drug development. These insights not only reshape our understanding of chaperone biology but also present opportunities for precision medicine in various human diseases. Full article

Background/Objectives: Colorectal cancer (CRC) is one of the most prevalent malignancies; this issue underlines the need for accurate molecular biomarkers for early detection and accurate prognosis. Circular RNAs (circRNAs) have recently emerged as very promising cancer biomarkers. The circular transcript of the chaperonin-containing TCP1 subunit 3 (CCT3) gene, namely circ-CCT3, is a significant oncogenic driver. In gastrointestinal malignancies, circ-CCT3 promotes tumor growth by sponging tumor-suppressor miRNAs. In this study, we examined whether circ-CCT3 expression can predict the prognosis of patients diagnosed with colorectal adenocarcinoma, the most frequent type of CRC. Methods: Total RNA was extracted from pulverized, fresh frozen colorectal tissues and reverse-transcribed. A previously developed, highly sensitive quantitative PCR (qPCR) assay was applied to determine circ-CCT3 expression in 216 primary colorectal adenocarcinoma tissue specimens and 86 paired normal colorectal tissues. Results: circ-CCT3 was significantly upregulated in colorectal adenocarcinoma tissues, in comparison to their non-cancerous tissue counterparts. Higher circ-CCT3 expression was associated with a poorer disease-free (DFS) and overall survival (OS) of colorectal adenocarcinoma patients. Interestingly, multivariate Cox regression showed that the prognostic value of circ-CCT3 expression regarding DFS was independent of other established prognosticators used in clinical practice, including TNM staging. Furthermore, the stratification of patients based on the TNM classification of the tumors revealed that increased circ-CCT3 levels predicted shorter DFS and OS intervals, especially in the subgroup of TNM stage II or III patients. Conclusions: Our study provides evidence that circ-CCT3 overexpression constitutes a promising molecular biomarker of poor prognosis in colorectal adenocarcinoma, independently predicting tumor recurrence. Full article

Mechanistic relationships between heat shock protein 90 (HSP90) and human epidermal growth factor receptor 2 (HER2) are complex and clinical correlations in breast cancer remain inconsistent. We investigated the role of HSP90 expression in the response of breast cancer cells to HER2-targeted treatments, by measuring cell viability/proliferation and protein expression after genetic and pharmacologic HER2/HSP90 modulation. HSP90 expression was also assessed by immunohistochemistry in a series of 72 metastatic, HER2+ breast cancer patients. In HER2+ breast cancer models (AU565, BT474, MCF7-HER2), HER2 downregulation induced HSP90 upregulation and growth inhibitory synergism between trastuzumab and docetaxel. HSP90 downregulation blunted the response to trastuzumab and docetaxel and their synergistic interactions. The addition of pertuzumab caused little additional growth inhibition, but HSP90 silencing unmasked a synergistic growth inhibitory effect with the triple combination. Conversely, HSP90 downregulation blunted the therapeutic response to trastuzumab/pertuzumab/tamoxifen or trastuzumab–emtansine. In HER2+ breast cancer patients, high HSP90 expression was associated with significant progression-free survival benefit with the triple combination, as compared with trastuzumab and chemotherapy, although the interaction test was not statistically significant. Overall, our results highlight a mechanistic role for HSP90 in determining the response of breast cancer cells to HER2-targeted agents and suggest that trastuzumab/pertuzumab combinations may be particularly advantageous in HSP90-high, HER2+ breast cancer. Full article

The contribution of the environment to protein folding seems obvious. The aqueous environment directs protein folding towards generating a centric hydrophobic core with a polar shell. The cell membrane environment—in which numerous proteins are anchored—to stabilise the arrangement, expects the exposure of hydrophobic residues and the concentration of polar residues in the central part—a channel for the transport of numerous molecules. The influence of these environments seems evident due to the persistent residence of proteins in their surroundings providing an external force field for structure stabilisation. Structural forms are also obtained with the participation of supporting proteins—such as proteins from the heat shock protein group—which accompany the folding process and temporarily provide an appropriate external force field in which the protein, having obtained the correct structure for its activity, is released from interaction with the supporting protein. This paper discusses an example of the contribution of Hsp104 to casein folding and the effect of disaggregase preventing inappropriate aggregation. For this purpose, a model called the fuzzy oil drop (FOD-M) was used, which takes hydrophobic interactions into account in the assessment of protein structure status. Their distribution in the protein body highlights the contribution and influence of the external force field—originating from Hsp104 and the disaggregase in this case. Full article

Chaperonin 60 proteins plays an important role in plant growth and development as well as the response to abiotic stress. As part of the protein homeostasis system, molecular chaperones have attracted increasing attention in recent years due to their involvement in the folding and assembly of key proteins in photosynthesis. However, little is known about the function of maize chaperonin 60 protein. In the study, a gene encoding the chaperonin 60 proteins was cloned from the maize inbred line B73, and named ZmCpn60-3. The gene was 1, 818 bp in length and encoded a protein consisting of 605 amino acids. Phylogenetic analysis showed that ZmCpn60-3 had high similarity with OsCPN60-1, belonging to the β subunits of the chloroplast chaperonin 60 protein family, and it was predicted to be localized in chloroplasts. The ZmCpn60-3 was highly expressed in the stems and tassels of maize, and could be induced by exogenous plant hormones, mycotoxins, and pathogens; Overexpression of ZmCpn60-3 in Arabidopsis improved the resistance to Pst DC3000 by inducing the hypersensitive response and the expression of SA signaling-related genes, and the H₂O₂ and the SA contents of ZmCpn60-3-overexpressing Arabidopsis infected with Pst DC3000 accumulated significantly when compared to the wild-type controls. Experimental data demonstrate that flg22 treatment significantly upregulated transcriptional levels of the PR1 defense gene in ZmCpn60-3-transfected maize protoplasts. Notably, the enhanced resistance phenotype against Pseudomonas syringae pv. tomato DC3000 (Pst DC3000) in ZmCpn60-3-overexpressing transgenic lines was specifically abolished by pretreatment with ABT, a salicylic acid (SA) biosynthetic inhibitor. Our integrated findings reveal that this chaperonin protein orchestrates plant immune responses through a dual mechanism: triggering a reactive oxygen species (ROS) burst while simultaneously activating SA-mediated signaling cascades, thereby synergistically enhancing host disease resistance. Additionally, yeast two-hybrid assay preliminary data indicated that ZmCpn60-3 might bind to ZmbHLH118 and ZmBURP7, indicating ZmCpn60-3 might be involved in plant abiotic responses. The results provided a reference for comprehensively understanding the resistance mechanism of ZmCpn60-3 in plant responses to abiotic or biotic stress. Full article

Background/Objectives: Acute myeloid leukemia (AML) is an aggressive malignancy marked by high relapse rates and molecular heterogeneity, necessitating the identification of novel therapeutic targets. T-complex protein 1 (TCP1), a chaperonin implicated in protein folding, remains underexplored in AML pathogenesis. This study investigates the functional role of TCP1 in AML progression and evaluates its therapeutic potential. Methods: Using successive generations of xenografted tumor models, we systematically assessed the correlation between TCP1 expression and AML tumorigenicity. Functional consequences of TCP1 silence were evaluated through in vitro proliferation assays and in vivo tumor growth monitoring. Two distinct inhibitory strategies were employed: miR-340-5p-mediated transcriptional silencing and FTY720-induced disruption of TCP1 chaperone activity. Mechanistic insights were derived from ubiquitin–proteasome pathway analysis, cell cycle profiling, and apoptosis assays. Results: High TCP1 expression correlated strongly with enhanced AML tumorigenicity. Knockdown of TCP1 significantly inhibited AML cell growth and induced degradation of AML1-ETO and PLK1 proteins through the ubiquitin–proteasome pathway. miR-340-5p effectively silenced TCP1 expression, exhibiting an inverse correlation with TCP1 levels. FTY720 disrupted TCP1′s chaperone function, leading to cell cycle arrest, apoptosis, and reduced xenograft tumor growth in murine models. Conclusion: Our findings establish TCP1 as a promising therapeutic target for AML. Both miR-340-5p and FTY720 demonstrate potent anti-leukemic effects by suppressing TCP1 activity, highlighting their potential as novel strategies to inhibit AML proliferation and improve therapeutic outcomes. Full article

HtpB, the chaperonin of the bacterial pathogen L. pneumophila, is found in extracellular locations, even the cytoplasm of host cells. Although chaperonins have an essential cytoplasmic function in protein folding, HtpB exits the cytoplasm to perform extracellular virulence-related functions that support L. pneumophila’s lifestyle. The mechanism by which HtpB reaches extracellular locations is not currently understood. To address this experimental gap, immunoelectron microscopy, trypsin-accessibility assays, and cell fractionation were used to localize HtpB in various L. pneumophila secretion mutants. Dot/Icm type IV secretion mutants displayed less surface-exposed HtpB and more periplasmic HtpB than parent strains. The analysis of periplasmic extracts and outer membrane vesicles of these mutants, where HtpB co-localized with bona fide periplasmic proteins, confirmed the elevated levels of periplasmic HtpB. Genetic complementation of the mutants recovered parent strain levels of surface-exposed and periplasmic HtpB. The export of GSK-tagged HtpB into the cytoplasm of infected cells was also Dot/Icm-dependent. The translocating role of the Dot/Icm system was not specific for HtpB because GroEL, the chaperonin of Escherichia coli, was found at the cell surface and accumulated in the periplasm of Dot mutants when expressed in L. pneumophila. These findings establish that a functional Dot/Icm system is required for HtpB to reach extracellular locations, but the mechanism by which cytoplasmic HtpB reaches the periplasm remains partially unidentified. Full article