Search Results (301)

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

Non-covalent molecular self-assembly serves as a distinctive strategy for enhancing the mechanical performance of lignin-based composite hydrogels. Nevertheless, the self-assembly process can be significantly influenced, leading to alterations in the nanostructure of the hydrogel, because of the diverse conformational reorganizations of lignin in different solvents. In this research, a solvent exchange process was employed to generate a phase-separated structure comprising hydrophobic lignin domains and hydrophilic poly(N,N-dimethylacrylamide) (PDMA) domains through the aggregation of lignin, thereby forming tough lignin/PDMA hydrogels. By adjusting the solvent composition, the hydrogels exhibit distinct nanostructural transformations that are precisely correlated with the changes in Hansen Solubility Parameters (HSPs) of the solvent mixtures. Balanced HSPs facilitates the formation of small-scale lignin domains with high-domain density, which act as crosslinking points for the establishment of a reinforced network. Remarkably, lignin/PDMA hydrogels prepared at a boundary solvation condition unexpectedly induced the formation of large and highly condensed lignin domains, which displayed a radius of gyration (Rg) of 7.7 nm and an inter-domain distance (d-spacing) of 98.1 nm within the hydrogel network. These unique nanostructural features further contribute to its superior mechanical performance, including excellent tensile strength of 3.2 MPa, Young’s modulus of 5.7 MPa, and fracture energy of 41.2 kJ m⁻², which outperforms most reported lignin hydrogels. Additionally, it offers a strong adhesion and rapid drying approach, rendering the hydrogel more suitable for applications as hydrogel coatings. Full article

Small heat shock proteins (HSP20s) are known to function as molecular chaperones that bind to denatured proteins under high-temperature stress and assist in their conformational recovery, thereby contributing to plant thermotolerance. In the present study, three HSP20 genes—PcHSP12.8, PcHSP12.9, and PcHSP13.4—were identified in the transcriptome of Polygonatum cyrtonema Hua. Bioinformatics analysis indicated their phylogenetic relationships, conserved domains, and potential tertiary structures. RT-qPCR analysis revealed up-regulation of all three genes in response to heat stress. Subcellular localization studies further suggested that PcHSP12.8, PcHSP12.9, and PcHSP13.4 are predominantly localized in the nucleus. Heterologous expression of these genes in a heat-sensitive yeast mutant appeared to improve cell survival under heat stress relative to the control strain. In Arabidopsis thaliana overexpressing these genes, moderate improvements in germination rate, root elongation, and stress survival were observed compared to wild-type plants under heat stress. Transgenic lines also showed a tendency toward reduced reactive oxygen species accumulation, as reflected by decreased 3,3′-diaminobenzidine (DAB) and nitroblue tetrazolium (NBT) staining, together with increased activities of catalase (CAT) and peroxidase (POD), as well as higher chlorophyll retention under thermal stress. Taken together, these findings imply that the three PcHSP20 genes could be involved in thermotolerance in P. cyrtonema. Full article

In the filamentous fungus Neurospora crassa, a gene not having a pairing partner during meiosis is seen as a potential intruder and is targeted by a mechanism called meiotic silencing by unpaired DNA (MSUD). MSUD employs core RNA interference (RNAi) components such as the SMS-2 Argonaute, which uses small interfering RNAs (siRNAs) as guides to seek out mRNAs from unpaired genes for silencing. In Drosophila melanogaster, the heat shock protein 70 (Hsp70) chaperone system facilitates the conformational activation of an Argonaute and allows it to load siRNAs. Here, our results demonstrate that an Hsp70 protein in Neurospora interacts with SMS-2 and mediates the silencing of unpaired genes. Full article

Potyvirus genomes are expressed as a single large open reading frame, which is translated into a polyprotein that is post-translationally cleaved by three virus-encoded proteases into 10 functional proteins. Several of these potyviral proteins, including nuclear inclusion protein b (NIb), are multifunctional. Here, using the classic GFP silencing in Nicotiana benthamiana gfp-transgenic plants, we show that potato virus Y (PVY) NIb, in addition to its canonical role as the viral RNA-dependent RNA polymerase (RdRP), functions as a suppressor of RNA silencing. Mutational analyses reveal a previously unreported NIb nuclear localization signal (NLS) consisting of a triple-lysine motif. NIb suppression of RNA silencing activity was lost when the NLS was mutated, suggesting that nuclear localization is required for NIb suppression of RNA silencing activity. Analysis of sequenced GFP siRNAs revealed three reproducible hotspot regions at ≈175 nt, ≈320–330 nt, and a broader 3′-proximal region spanning ≈560–700 nt that contains multiple local maxima. These data show differences in the positional distribution of siRNAs between samples expressing NIb and those expressing NIb^Del3×2, the NIb null mutant that does not suppress RNA silencing. However, the positional distribution of GFP-derived small RNAs across the transgene differed modestly between NIb and NIb^Del3×2, while both treatments showed the same three reproducible hotspot regions. Furthermore, NIb was found to interact with four key RNA silencing pathway proteins—AGO4, HSP70, HSP90, and SGS3. Except for HSP90, each of these proteins showed degradation products that were absent in NIb mutants that did not suppress RNA silencing. These findings support a role for NIb in countering host defense during virus infection. Full article

As a critically important global food crop, wheat has been increasingly threatened by the frequent occurrence of extreme high-temperature events, which impairs its growth and development, resulting in reduced seed-setting rate, compromised grain quality and diminished yield. Therefore, identifying heat-tolerant genes and enhancing thermotolerance through molecular breeding are essential strategies for wheat improvement. In this study, we retrieved spatial transcriptomic data from the public database PRJNA427246, which captured gene expression profiles in flag leaves and grains of the heat-sensitive wheat cultivar Chinese Spring (CS) under 37 °C heat stress at time points of 0 min, 5 min, 10 min, 30 min, 1 h, and 4 h. Weighted Gene Co-expression Network Analysis (WGCNA) was used to construct co-expression networks for flag leaf and grain transcriptomes. One highly significant module was identified in each tissue, along with 35 hub genes that showed a strong temporal association with heat stress progression. Notably, both modules contained the previously characterized thermotolerance gene TaMBF1c, suggesting that additional heat-responsive genes may be present within these modules. Simultaneous analysis of the expression data from four groups (encompassing different tissues and high-temperature treatments) for the 35 core genes revealed that genes from the TaHSP20 family, TaMBF1c family, and other related genes exhibit coordinated expression patterns in terms of the temporal dynamics and tissue distribution of stress responses. Additionally, 27 genes of the small heat shock protein (HSP20) family are predicted to be involved in the endoplasmic reticulum-associated degradation (ERAD) pathway. They assist in clearing misfolded proteins induced by stress, thereby helping to maintain endoplasmic reticulum homeostasis and cellular functions under stress conditions. Finally, the expression levels of three core genes, TaHSP20-1, TaPCDP4, and TaMBF1c-D, were validated by qRT-PCR in two wheat cultivars with distinct thermotolerance: S116 (Zhehuamai 2008) and S128 (Yangmai 33). These findings provide new insights into the molecular mechanisms underlying heat tolerance in wheat and offer valuable genetic resources for breeding thermotolerant varieties. Full article

We present a computational study that precedes the potential interactions between SARS-CoV-2 helicase (NSP13) and selected host proteins implicated in chaperone-assisted folding and polyamine metabolism. Using structure-based modelling and protein–protein docking (BioLuminate v4.6), followed by all-atom molecular dynamics (MD) simulations (GROMACS v2018.6), and comparative MM-GBSA scoring (HawkDock v2), we evaluated the stability and interface properties of NSP13 complexes with cytosolic heat shock proteins; heat shock protein 40 (HSP40), heat shock protein 70 (HSP70), heat shock protein 90 (HSP90) and the polyamine biosynthesis enzyme ornithine decarboxylase (ODC). Docking, MD, and interface analyses indicate distinct complex behaviours: HSP70-NSP13 complexes sampled compact conformations, HSP90-NSP13 ensembles displayed greater conformational heterogeneity but more favourable comparative MM-GBSA estimates, and ODC-NSP13 interfaces were comparatively well packed. Per-residue contact mapping identified a small set of recurrent NSP13 residues, Lys22 and Asn51, as putative interaction hotspots. The reported findings herein generate testable hypotheses about NSP13 recruitment of host chaperones and modulation of polyamine metabolism that may inform downstream experimental studies. Full article

The increasing threat of zoonotic malaria parasites of humans, such as Plasmodium knowlesi, make the search for improved pharmacotherapy imperative. Using protein sequence and structural analyses, phylogenetics, protein network mapping, protein–ligand interaction, and small molecule docking studies, we have identified for the first time the predicted structure, function, and druggability of the P. knowlesi heat shock protein 90s (PkHsp90s). Four isoforms were identified (in the cytosol, endoplasmic reticulum, mitochondrion, and apicoplast), and key structural differences were elucidated compared to human Hsp90s. In particular, the glycine-rich helix loop (GHL) motif of cytosolic PkHsp90 was predicted to have a straight conformation that forms a plasmodial-specific hydrophobic extension of the lid domain of the ATP-binding site, which was not observed for the cytosolic human Hsp90s, HSPC1 (Hsp90α), and HSPC3 (Hsp90β). Virtual screening identified for the first time a number of compounds from the ZINC database (ZINC22007970, ZINC724661072, and ZINC724661078) that were predicted to bind strongly to the GHL-associated pocket of PkHsp90, with weak or no binding to HSPC1. This study has provided a molecular framework in support of rational drug design, targeting PkHsp90s as a promising route for antimalarial drug development in the fight against zoonotic malaria. Full article

Exosomes are small extracellular vesicles found in body fluids. They contain proteins and nucleic acids that reflect the condition of the parent cell. Because of this, they may be useful in colorectal cancer (CRC) diagnostics. In this study we compared three plasma isolation methods: ultracentrifugation (UC), size exclusion chromatography (SEC), and a commercial Exo-spin kit. The material obtained with each method was checked for protein content, purity, and vesicle integrity using protein measurements, Western blots, and scanning electron microscopy. From these results SEC was chosen for further use. Exosomes isolated with this method were tested by an enzyme-linked immunosorbent assay (ELISA) for four CRC-related proteins: HSP70, CK19, CA125, and TAG72. Patient samples showed higher levels of HSP70, CK19, and CA125 than controls. TAG72 levels did not differ. In addition, men had more HSP70 than women. These findings show that SEC can be applied for exosome isolation from plasma and that specific proteins detected in exosomes, including HSP70, CK19, and CA125, may serve as promising markers for non-invasive colorectal cancer diagnosis and monitoring. Full article

Background: Heat shock protein 90 (HSP90) is a molecular chaperone that stabilizes numerous oncogenic proteins and supports tumor survival. Small molecules targeting HSP90 offer a novel approach to overcome drug resistance and immune suppression in breast cancer. Methods: A novel thiazolyl benzodiazepine (TB) containing a hydrazone moiety was evaluated in breast cancer cell lines (ER⁺ MCF-7, TNBC MDA-MB-231, and HER2⁺ SK-BR-3). Cytotoxicity was assessed using the CCK-8 assay, followed by PCR sequencing, flow cytometry, RT-qPCR, protein profiling, and HSP90 binding assays. Results: TB showed the strongest activity in MCF-7 cells (IC₅₀ = 7.21 µM) compared to MDA-MB-231 (IC₅₀ = 28.07 µM) and SK-BR-3 (IC₅₀ = 12.8 µM) cells. Mechanistic studies showed that TB binds to HSP90 (Kd = 3.10 µM), leading to disruption of the oncogenic signal. TB induced G2/M cell cycle arrest, promoted apoptosis via Bax and Caspase-3 activation, and suppressed cancer stem cell markers (NANOG, OCT4, SOX2). Additionally, TB activated immune-related pathways via ERK/MAPK signaling and upregulated genes such as SMAD2, SMAD3, and JUN.Conclusions: TB functions as an HSP90 inhibitor with dual anticancer and immunomodulatory properties in Estrogen Receptor-Positive (ER⁺) breast cancer cells. These findings suggest that TB represents a promising scaffold for the development of multi-targeted breast cancer therapies. Full article

Bradysia odoriphaga Yang et Zhang damages roots of 30 plant species, resulting in >50% yield loss. Heat stress can not only affect the survival but also affect the expression of heat shock proteins of B. odoriphaga. In this study, two small heat shock protein genes, Hsp21.9 and Hsp22.3, were cloned from B. odoriphaga. The full-length cDNA sequences of BoHsp21.9 and BoHsp22.3 were 749 and 941 bp in length and contained a 588 and 594 bp open reading frame (ORF), encoding a protein of 196 and 198 amino acids with a calculated molecular weight of 21.9 and 22.3 kDa and an isoelectric point of 6.84 and 6.91. Phylogenetic tree analysis showed that BoHsp21.9 and BoHsp22.3 clustered into one branch with flies. qRT-PCR analyses indicated that BoHsp21.9 and BoHsp22.3 were expressed in all tested developmental stages and body segments, especially induced by heat stress. RNAi-mediated silencing of BoHsp21.9 and BoHsp22.3 significantly decreased the survival rate of fourth-instar larvae when exposed to 38 °C. This is the first study on small heat shock proteins in B. odoriphaga, and BoHsp21.9, and BoHsp22.3 play important roles in the molecular mechanism of B. odoriphaga to theromotolerance. Full article

Laser-assisted hatching (LAH) is used during in vitro fertilization (IVF) to improve the chances of embryo implantation into the uterine wall by creating a small, precise opening in its outer shell (zona pellucida). The primary objective of this study was to evaluate the safety profile of LAH performed using an infrared femtosecond laser system (λ = 1028 nm, E = 155 nJ, and I = 6.5 TW/cm²). We aimed to identify and quantify the potential biological effects of the laser and compare them with results from previous studies that used visible wavelength laser pulses (λ = 514 nm, E = 49 nJ, and I = 2.5 TW/cm²). To achieve this, we designed a controlled experiment using a mouse model. A critical component of our safety assessment involved quantifying the levels of reactive oxygen species (ROS) and analyzing the expression of heat-shock proteins (HSPs). Robust analyses revealed no statistically significant differences in either ROS production or HSP expression—assessed at both the protein and mRNA levels—between embryos in the negative control group and those subjected to the femtosecond LAH procedure. This key finding indicates that neither infrared nor visible femtosecond laser microsurgery of the zona pellucida induced a detectable oxidative or thermal stress response within the tested parameters. Full article

Coumarin derivatives constitute a versatile small-molecule chemotype with broad anticancer potential. This narrative review synthesizes recent in vitro and in vivo evidence on coumarin-based scaffolds, emphasizing breast cancer and covering lung, prostate, and colorectal models. We summarize major mechanisms of action—including induction of apoptosis (caspase activation and BAX/BCL-2 balance), modulation of PI3K/Akt/mTOR signaling, inhibition of angiogenesis (VEGFR-2), interference with estrogen biosynthesis (aromatase/ER axis), chaperone targeting (Hsp90), and attenuation of multidrug resistance (efflux pumps/autophagy)—and highlight representative chemotypes (e.g., benzimidazole, triazole, furocoumarins, topoisomerase- and CDK-oriented hybrids). Where available, we contrast potency and selectivity across models (e.g., MCF-7 vs. MDA-MB-231; A549; PC-3; colon lines) and discuss structure–activity trends linking substituent patterns (heteroaryl linkers, judicious halogenation, polar handles) to pathway engagement. We also delineate translational gaps limiting clinical progress—selectivity versus non-malignant cells, incomplete pharmacokinetic and safety characterization, and limited validation beyond xenografts. Finally, we outline priorities for preclinical optimization: biology-aligned target selection with biomarkers, resistance-aware combinations (e.g., PI3K/mTOR ± autophagy modulation; MDR mitigation), and early integration of ADME/tox and PK/PD to confirm on-target exposure. Collectively, the evidence supports coumarins as adaptable, multi-target anticancer leads, particularly promising in hormone-dependent breast cancer while remaining relevant to other tumor types. Full article

Background/Objectives: Human papillomavirus (HPV) is the main causative agent of cervical cancer and contributes to a significant proportion of other anogenital and oropharyngeal malignancies. The need for better biomarkers and therapeutic approaches in HPV-associated cancers has drawn attention to exosomes, small extracellular vesicles known for their stability, biomolecule transport capabilities, and role in cell-to-cell communication. Methods: This review comprehensively evaluates recent literature on the diagnostic, prognostic, and therapeutic applications of small extracellular vesicles, particularly exosomes, in HPV-related cancers. It analyzes findings on exosomal nucleic acids, proteins, and long non-coding RNAs, as well as engineered exosome-based therapies. Results: Exosomal miRNAs (e.g., miR-204-5p, miR-99a-5p, miR-21), proteins (e.g., glycolytic enzymes, HSP90), and lncRNAs (e.g., HOTAIR, DLEU1) have emerged as promising biomarkers for disease detection and monitoring. Exosomal cargo actively participates in HPV-related tumor progression. For example, miRNAs such as miR-21 and miR-146a modulate immune cell polarization and inflammatory signaling, while lncRNAs like HOTAIR promote oncogenic transcriptional programs. Exosomal proteins including HSP90 and ANXA1 facilitate extracellular matrix remodeling and immune evasion, thereby influencing tumor growth and metastasis. In HPV-positive head and neck and cervical cancers, exosomal cargo reflects HPV status, tumor progression, and treatment response. Therapeutic studies demonstrate the utility of exosomes in vaccine delivery, immune modulation, and drug delivery systems, including the use of PROTACs. However, clinical translation faces barriers including isolation protocol standardization, biomarker validation, and scalable production. Conclusions: Exosomes hold great promise for integration into diagnostic and therapeutic workflows for HPV-related cancers. Future research should focus on resolving standardization issues, validating biomarkers in diverse cohorts, and optimizing engineered exosome platforms for targeted therapy. Full article

Background/Objectives: Henoch–Schönlein purpura (HSP), or IgA vasculitis, is the most common small-vessel vasculitis in children, yet Indian cohort data remain limited. We aimed to describe the clinical profile, renal involvement, treatment patterns, relapse, and outcomes of pediatric HSP at a tertiary centre in South India. Methods: We conducted a retrospective review of children <18 years diagnosed with HSP (January 2013–October 2018) using EULAR/PRINTO/PRES criteria. Demographics, clinical features, laboratory parameters, treatments, and outcomes were abstracted from records and analyzed in SPSS (descriptive statistics; Chi-square/Fisher’s exact and t/non-parametric tests as appropriate). Subgroup comparisons included renal vs. non-renal disease and age <6 vs. ≥6 years. An exploratory analysis examined predictors of nephritis. Results: Of 43 children identified, 2 were excluded (misclassified as systemic lupus erythematosus); 41 were analyzed. Mean age was 8.5 years (range 3–17), male: female 1.4:1. A preceding febrile illness or upper respiratory tract infection was noted in 41.4% and 17%, respectively. Palpable purpura was universal; joint involvement 73.1%, abdominal pain 61.0%, vomiting 41.5%. Renal involvement 17% occurred only in children ≥6 years; exploratory testing supported a strong age-linked signal for nephritis. Laboratory abnormalities included anemia (48.7%), thrombocytosis (19.5%), and elevated ESR (51.2%). Skin biopsy (n = 29) showed IgA and complement deposition; renal biopsy (n = 2) showed ISKDC grades II–III. Treatments included NSAIDs 71.6%, corticosteroids 31.7%, and dapsone 24.4% (used for severe systemic/persistent cutaneous disease). Rash relapse 7.3% clustered with joint plus abdominal symptoms and was not observed among children with nephritis. At a mean 18.9-month follow-up, one child required long-term antihypertensives; no child progressed to end-stage renal disease. Conclusions: Pediatric HSP in this South-Indian cohort followed a largely self-limited course with favourable renal outcomes. Age ≥6 years flagged higher renal risk, supporting age-targeted urine and blood-pressure surveillance, while relapse appeared to follow a non-renal trajectory (joint/abdominal clustering). Steroid and dapsone use reflected clinical severity rather than relapse risk. Findings align with Indian series and suggest lower renal morbidity than some East-Asian reports, adding region-specific evidence to guide monitoring and counselling. Full article