Biomolecules最新文献

Background: In nuclear medicine, numerous cancer types are treated via internal irradiation with radiopharmaceuticals, including low-LET (linear energy transfer) beta-emitting radionuclides like Lu-177. In most cases, such treatments lead to low-dose exposure of organ systems with β-irradiation, which induces only few isolated DSBs (double-strand breaks) in the nuclei of hit cells, the most threatening DNA damage type. That damaging effect contrasts with the clustering of DNA damage and DSBs in nuclei traversed by high-LET particles (α particles, ions, etc.). Methods: After in-solution β-irradiation for 1 h with Lu-177 leading to an absorbed dose of about 100 mGy, we investigated the spatial nano-organization of chromatin at DSB damage sites, of repair proteins and of heterochromatin marks via single-molecule localization microscopy (SMLM) in PBMCs. For evaluation, mathematical approaches were used (Ripley distance frequency statistics, DBScan clustering, persistent homology and similarity measurements). Results: We analyzed, at the nanoscale, the distribution of the DNA damage response (DDR) proteins γH2AX, 53BP1, MRE11 and pATM in the chromatin regions surrounding a DSB. Furthermore, local changes in spatial H3K9me3 heterochromatin organization were analyzed relative to γH2AX distribution. SMLM measurements of the different fluorescent molecule tags revealed characteristic clustering of the DDR markers around one or two damage foci per PBMC cell nucleus. Ripley distance histograms suggested the concentration of MRE11 molecules inside γH2AX-clusters, while 53BP1 was present throughout the entire γH2AX clusters. Persistent homology comparisons for 53BP1, MRE11 and γH2AX by Jaccard index calculation revealed significant topological similarities for each of these markers. Since the heterochromatin organization of cell nuclei determines the identity of cell nuclei and correlates to genome activity, it also influences DNA repair. Therefore, the histone H3 tri methyl mark H3K9me3 was analyzed for its topology. In contrast to typical results obtained through photon irradiation, where γH2AX and H3K9me3 markers were well separated, the results obtained here also showed a close spatial proximity ("co-localization") in many cases (minimum distance of markers = marker size), even with the strictest co-localization distance threshold (20 nm) for γH2AX and H3K9me3. The data support the results from the literature where only one DSB induced by low-dose low LET irradiation (<100 mGy) can remain without heterochromatin relaxation for subsequent repair.

The aggregation of tau protein is a central pathological event in Alzheimer's disease, and this pathology is hypothesized to spread via a prion-like mechanism driven by tau "seeds". While aggregated tau from Alzheimer's disease brains is known to contain age-related d-isomerized aspartic acid (d-Asp) residues, it remains unknown how this modification affects the seeding activity that drives disease propagation. Here, we investigated the impact of site-specific d-isomerization within R2 and R3 tau repeat-domain peptides, which form the core of tau fibrils. We demonstrate that the stereochemical integrity of these peptides is critical for their seeding function. d-isomerization at Asp314 within the R3 peptide seed severely impaired its ability to template the fibrillization of full-length tau in vitro. This finding was validated in a cellular model, where R3 seeds containing d-Asp314 were significantly less potent at inducing the formation of phosphorylated tau aggregates compared to wild-type seeds. Our results establish that Asp d-isomerization within tau seeds acts as a potent attenuator of their pathological seeding activity, suggesting this spontaneous modification may intrinsically modulate the progression of Alzheimer's disease.

Capsaicin, a naturally occurring polyphenol, is known to affect energy expenditure and muscle fatigue and modulate contractions in skeletal muscle. The L-type Ca²⁺ channels are known to be an important ion channel involved in the various muscle functions and the effect of capsaicin on the skeletal L-type Ca²⁺ channels is currently unknown. In this study, the effects of capsaicin and capsaicin analogs on depolarization-induced Ca²⁺ effluxes through L-type Ca²⁺ channels in transverse tubule membranes from rabbit skeletal muscle and L-type Ca²⁺ currents recorded using the whole-cell patch clamp technique in rat myotubes were examined. Capsaicin, in the concentration range of 3-100 µM, inhibited depolarization-induced Ca²⁺ effluxes. The effect of capsaicin was not reversed by TRPV1 antagonist SB-366791 (10 µM). While vanilloids (30 µM) including vanillin, vanillyl alcohol, and vanillylamine were ineffective, other capsaicinoids (30 µM) including dihydrocapsaicin, nonivamide, and nordihydrocapsaicin significantly inhibited Ca²⁺ effluxes, suggesting that hydrocarbon chains are required for inhibition. In rat myotubes, capsaicin inhibited L-type Ca²⁺ currents with an IC₅₀ value of 27.2 μM in the presence of SB-366791. Furthermore, in docking studies and molecular dynamic simulations, capsaicinoids with an aliphatic tail showed stronger binding and stable bent conformations in CaV1.1, forming hydrogen bonds with Ser1011 and Thr935 and hydrophobic/π-alkyl contacts with Phe1008, Ile1052, Met1366, and Ala1369, resembling the binding mode of amlodipine. In conclusion, the results indicate that the function of L-type Ca²⁺ channels in mammalian skeletal muscle was inhibited by capsaicin and capsaicin analogs in a TRPV1-independent manner.

Connective tissue disease-associated pulmonary arterial hypertension (CTD-PAH) is a severe form of pulmonary hypertension with poor prognosis. It most commonly arises in systemic sclerosis (SSc), followed by systemic lupus erythematosus (SLE) and mixed connective tissue disease (MCTD). Its pathogenesis involves a complex interplay of immune dysregulation, chronic inflammation, endothelial injury, vascular remodeling, and fibrosis. Although vasodilators targeting the endothelin, nitric oxide, and prostacyclin pathways remain the therapeutic backbone, newer agents-including the activin signal inhibitor sotatercept and inhaled treprostinil-have expanded treatment options. Immune-targeted therapies such as glucocorticoids, cyclophosphamide, mycophenolate mofetil, rituximab, and IL-6 receptor inhibitors may benefit inflammation-dominant PAH phenotypes, while fibrotic phenotypes continue to demonstrate limited responsiveness. In addition to brain natriuretic peptide (BNP), N-terminal (NT)-proBNP and disease-specific autoantibodies, emerging biomarkers show promise for early detection, risk stratification, and personalized treatment, though validation in CTD-PAH is lacking. Advances in animal models replicating immune-mediated vascular injury and fibrosis have further improved mechanistic understanding. Despite these developments, substantial unmet needs remain, including the absence of disease-specific therapeutic strategies, limited biomarker integration into clinical practice, and a scarcity of large, well-designed trials targeting individual CTD subtypes. Addressing these gaps will be essential for improving prognosis in patients with CTD-PAH.

Post-cardiac arrest syndrome (PCAS) remains a major cause of mortality and neurological impairment following successful resuscitation, yet the mechanisms linking global ischemia-reperfusion injury to microvascular and systemic dysfunction are not yet completely understood. While prior work has focused on inflammation, endothelial injury, and circulatory collapse, the central role of platelets in coordinating these pathological processes has not been comprehensively examined. This review provides the first integrated framework positioning platelets as core modulators, rather than secondary participants, in PCAS pathophysiology. We synthesize emerging evidence demonstrating that ischemia and reperfusion transform platelets into potent thromboinflammatory effectors through oxidative stress, DAMP-mediated pattern recognition signaling, and mitochondrial dysfunction. Hyperactivated platelets drive cerebral microthrombus formation, coronary no-reflow, and peripheral organ hypoperfusion, while platelet-leukocyte aggregates, neutrophil extracellular traps, and platelet-derived microparticles amplify systemic inflammation and endothelial injury. We further highlight the clinical significance of dynamic platelet dysfunction in coagulopathy, prognostication, and responses to post-arrest therapies including targeted temperature management and ECMO. Finally, we outline a novel, platelet-centered therapeutic paradigm, emphasizing selective interventions, such as GPVI inhibition, P-selectin blockade, FXI/XIa inhibition, and NETosis modulation, that target pathological platelet activity while preserving essential hemostatic function. In this review, by reframing platelets as the central determinants of PCAS, we report new mechanistic insights and therapeutic opportunities that are complementary to the existing post-arrest strategies and have the potential to improve survival and neurological outcomes after cardiac arrest.

This review examines the application of Artificial Intelligence (AI) in the discovery and optimisation of neuroprotective natural products (NPs) for neurodegenerative diseases (NDDs), emphasising the transition from general computational drug discovery to AI-specific approaches designed to address the chemical complexity and bioactivity profiles of natural compounds. The discussion encompasses relevant datasets, AI models, illustrative case studies, and emerging protein and biological targets that may serve as potential points of intervention for the prevention and treatment of NDDs. The review is organised to guide the reader from foundational knowledge to applied strategies; it begins by outlining the chemical and biological principles underlying neuroprotective NPs, then presents AI-driven computational frameworks for NP discovery, followed by a detailed examination of recent case studies in NDDs. Subsequent sections address the key challenges, opportunities, and future directions in the field, concluding with an evaluation of prospects for interdisciplinary collaboration across medicinal chemistry, neuroscience, and artificial intelligence.

Arginine is a semi-essential amino acid for adults, which serves as a central hub synthesizing various metabolites. Arginine plays a critical role in carcinogensis. As a polar amino acid, the uptake and the transportation of arginine across cell membrane systems rely on transporter proteins. Arginine transporters remain critically important, particularly as potential biomarkers and therapeutic targets in cancer. Based on the subcellular localization, arginine transporters could be divided into two types: cell membrane arginine transporters and intracellular membrane arginine transporters. This review aims to investigate the latest advancements of arginine transporter proteins in cancer, focusing on their cellular localization, structural characteristics, and mechanism, with the goal of promoting the design and development of targeted anticancer therapeutics against these transporters.

Peptide cyclization is a strategy to improve biological stability and functional activity, but direct comparison between linear and cyclic peptides with the same sequence is still limited. In this study, linear (L-CR5) and cyclic (C-CR5) forms were synthesized, and biological functions such as antioxidant, whitening, and anti-wrinkle activity were compared and evaluated. C-CR5 showed about 22.3 times of DPPH radical scavenging activity, which was significantly stronger than L-CR5, and tyrosinase inhibition increased rapidly in C-CR5 to reach inhibition of 95% or more, whereas L-CR5 showed only moderate activity in the same range (about 6.5 times). MMP-1 expression in the evaluation of anti-wrinkle activity did not show a decreasing trend in L-CR5 at all, while C-CR5 showed an anti-wrinkle effect, which was reduced by about 92.8% at 400 μg/mL. As a result of molecular docking analysis, C-CR5 exhibited lower MolDock scores than L-CR5 toward both tyrosinase and MMP-1, indicating a potentially higher binding affinity and improved binding stability. This is expected to be due to reduced structural flexibility and optimized residue directions (especially Tyr and Arg). These results indicate that peptide cyclization is an example of enhanced functional bioactivity of CYGSR and provides a positive case for the structure-activity relationship.

Disruption of the blood-milk barrier and inhibition of enzymatic activity caused by abnormal external stimuli, accompanied by the occurrence of autophagy, are among the major factors contributing to the onset of clinical mastitis (CM) in dairy cows. However, the molecular mechanisms through which external stimuli and autophagy regulate CM in dairy cows are not fully understood. This study examined mammary gland (MG) tissue samples collected from healthy dairy cows and those with CM caused by Staphylococcus aureus (n = 3 per group) to observe histological changes and autophagic phenomena, identify candidate biomolecular targets involved in external stimuli in dairy cows affected by mastitis through proteomic and bioinformatic analyses, and analyze their expression and distribution patterns in MG tissues. Pathological examination revealed that the MG tissues of the CM group exhibited significant alveoli collapse and inflammatory cell infiltration, accompanied by autolysosome and phagolysosome activation, and elevated expression of lysosomal and autophagic markers. Bioinformatic analysis identified five biological processes (BPs) and 144 differentially expressed proteins (DEPs) associated with external stimuli, among which beclin 1 (BECN1) was involved in all five BPs. Pathway enrichment analysis revealed that BECN1 participated in six autophagy-related signaling pathways. BECN1 was localized in the cytoplasm of mammary epithelial cells, and both mRNA and protein levels of BECN1 were significantly upregulated in the CM group compared with those in the controls (p < 0.01). These findings suggest that BECN1 expression is closely associated with CM in dairy cows and correlates with autophagy-related responses to external stimuli, and its elevated expression is positively correlated with Staphylococcus aureus-induced CM severity. Our results offer preliminary observations relevant to the molecular mechanisms by which BECN1, the autophagy-regulating biomolecule BECN1 influences the development of CM.