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Biochimica et Biophysica Acta (BBA) - General Subjects

Elsevier BV

Preprints posted in the last 30 days, ranked by how well they match Biochimica et Biophysica Acta (BBA) - General Subjects's content profile, based on 16 papers previously published here. The average preprint has a 0.01% match score for this journal, so anything above that is already an above-average fit.

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Exploring the Mechanism of Na⁺/K⁺-ATPase (NKA) and 20-HETE Ligand Interactions by in-silico modeling

Faleel, D.; Arnest, R.; Aradhyula, V.; Boyapalli, S.; Haller, S. T.; Kennedy, D. J.

2026-05-15 bioinformatics 10.64898/2026.05.12.724327 medRxiv
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The Na+/K+-ATPase (NKA) regulates ion balance in the kidney and influences cellular processes like proliferation and apoptosis through its signal transduction. The endogenous ligand 20-Hydroxyeicosatetraenoic acid (20-HETE) contributes to inflammation and fibrosis in chronic kidney disease (CKD) and inhibits NKA activity in renal tubules. However, the molecular mechanism of this interaction remains unclear. In this study, we used in-silico approach to investigate the potential interaction between 20-HETE and NKA. Various ligands, including known NKA ligands such as cardiotonic steroids (CTS), 20-HETE, and negative controls, were docked using rigid and Induced Fit Docking to predict the affinity of the ligands toward NKA. Binding free energy calculations with the Prime Molecular mechanics with generalized Born and surface area (Prime MM/GBSA) tools were used to confirm the involvement of key amino acids in ligand-receptor interactions. The docking analyses revealed that 20-HETE exhibited a binding affinity comparable to negative control, with some differences between rigid and induced fit docking. Binding free energy data highlighted key amino acids in the 20-HETE and NKA interaction. Interaction fingerprint and mutations such as Ala330Gly and Val329Ala significantly reduced binding free energy, while Thr804Ala showed a notable decrease, underscoring the potential importance of these amino acids in ligand stabilization. These findings provide computational evidence supporting potential direct interaction between 20-HETE and NKA and identify candidate residues for future experimental validation.

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Activation by statins unveils two putative agonist binding sites in the pore domain of TRPA1

Startek, J. B.; Milici, A.; Held, K.; Talavera, A.; Talavera, K.

2026-05-12 pharmacology and toxicology 10.64898/2026.05.08.723702 medRxiv
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TRPA1 is a non-selective cation channel that plays a crucial role in several pain and inflammatory conditions. Agents reducing membrane cholesterol decrease TRPA1 activation, but it remains unclear how cholesterol-lowering medications affect TRPA1 function. Given that TRPA1 is activated by a wide variety of chemicals, we explored whether statins have acute effects on this channel. We found that five commonly used statins activate human and mouse TRPA1 in a reversible and concentration-dependent manner. The effective concentrations were above the micromolar range, in the order: simvastatin {approx} lovastatin < fluvastatin < atorvastatin < pravastatin. Statin-induced activation was not correlated to changes in membrane order, nor mediated by N-terminal cysteine residues contributing to electrophilic compound agonism. Molecular docking calculations and the functional characterization of single-point mutants revealed two separate putative binding sites, one situated close to the kink of transmembrane segment 5 (TM5) and the other at the interface between TM4 and TM5. The mTRPA1 inhibitor A-967079 largely abrogated the response to the electrophilic agonist allyl isothiocyanate, but had weaker and varied effects across different statins and menthol. Mutation T877L strongly altered the effect of A-967079, also in an agonist-dependent manner, suggesting competitive binding between this antagonist and the non-electrophilic agonists. The identification of two distinct agonist binding sites may help explaining how TRPA1 is able to respond to a large variety of non-electrophilic compounds, while the finding of competitive interactions at one of these sites may help guide the development of agonist-specific antagonists of therapeutic relevance.

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Domain Dissolution in Supported Lipid Bilayers Triggered by Unsaturated Phospholipid Addition

Odudimu, A. T.; Wittenberg, N. J.

2026-05-22 biophysics 10.64898/2026.05.20.726269 medRxiv
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Significant cellular processes, including protein sorting, signal transduction, and pathogen entry, amongst others, are associated with membrane microdomains, also known as lipid rafts. Lipid rafts, due to their unique biophysical properties compared to their surrounding environment, which stem from their distinct lipid and protein profiles, have garnered interest in methods and techniques that tune their coexisting liquid-ordered/liquid-disordered state, aiming to disrupt or destabilize them. Since cholesterol stabilizes the membrane domain, cholesterol-depleting compounds like cyclodextrin can be used to destabilize and disrupt the membrane rafts. Overall, given the membrane rafts importance in biological processes, it is crucial to understand the biophysical factors that influence its stability. In this study, we present a new method for disrupting and dissolving lipid rafts in a model system of phase-separated supported lipid bilayer (SLB) patches composed of DOPC, DPPC, and cholesterol. Using fluorescence microscopy to monitor the liquid ordered (Lo) and liquid disordered (Ld) phases of the SLB patches, we observed that adding DOPC liposomes causes a transformation of the co-existing Ld and Lo phases into a single-phase bilayer. On the other hand, adding liposomes that match the lipid content of the phase-separated SLB patch increase the areas of the existing Ld and Lo phases. This work also offers a new method for redistributing raft-localized molecules, confirmed by tracking the redistribution of cholera toxin bound to GM1 after domain dissolution with DOPC liposomes. The work describes an alternative method for dynamically altering membrane composition and dissolving domains via liposome addition, rather than lipid depletion or exchange.

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ARHGEF7 S-glutathionylation promotes cancer cell migration through Rac1 activation

Schiff, W. H.; Shivamadhu, M. C.; Mashhadi Ramezani, F.; Kukulage, D. S. K.; Padmavathi, R.; Ahn, Y.-H.

2026-05-06 biochemistry 10.64898/2026.05.01.722049 medRxiv
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Reactive oxygen species (ROS) are central signaling molecules in many biological processes by inducing oxidative modifications of protein cysteine residues, including S-glutathionylation. Increasing evidence supports that ROS contribute to cancer progression via promoting cancer cell migration, invasion, and metastasis. Nevertheless, the protein targets of S-glutathionylation that regulate cancer cell motility remain ill-defined. In this study, we report on the redox regulation of ARHGEF7, a guanine nucleotide exchange factor highly expressed in metastatic cancer cells, that plays a major role in regulating cell migration. Our data demonstrates that ARHGEF7 is selectively glutathionylated at the highly conserved C312 residue in its PH domain, which is implicated in regulating its enzymatic activity. Breast cancer cell lines showed increased cell migration and invasion upon glutathionylation of ARHGEF7 at C312 in response to both oxidative stress and epidermal growth factor (EGF). Mechanistically, upon C312 glutathionylation, ARHGEF7 exhibited significantly enhanced binding to Rac1 and increased Rac1 recruitment to the cell membrane and lamellipodia. ARHGEF7 S-glutathionylation also increased its enzymatic rate of GDP-GTP nucleotide exchange, resulting in Rac1 activation. Consequently, ARHGEF7 C312 S-glutathionylation induced Rac1-PAK1 activation and their downstream pathways, including LIMK1 and MEK1, thereby enhancing migration and invasion. Our data reveal a new redox player in cell migration, with its potential implications for ROS-induced cancer progression.

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The Impact of Dysregulated Lipid Metabolism on the Gut-Brain Axis in Patients with Intracerebral Hemorrhage

Wang, G.; Chen, J.-h.; Qiao, Z.; Guo, D.; Guo, P.; Wang, A.; Sun, W.; Lyu, J.

2026-05-12 biochemistry 10.64898/2026.05.07.723656 medRxiv
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BACKGROUNGBisphenol A (BPA) has been linked to hypertension and disturbances in lipid metabolism; however, limited evidence is available regarding its association with hypertensive intracerebral hemorrhage (ICH). METHODSA multicenter, retrospective case-control study was conducted involving 129 participants, including individuals from an ICH group and healthy controls. Standard assays were employed to assess serum thyroid function, lipid profiles, serum fatty acid-binding [x]protein 4 (FABP4), oxidative stress markers, gap junction proteins, Wnt/{beta}-catenin signaling pathway activity, and expression changes of S100A8-mediated inflammatory cytokines involved in gut-brain interactions. Correlation analyses using Pearson and Spearman methods revealed that both BPA exposure and low T3 levels were significantly associated with elevated diastolic blood pressure, altered lipid metabolism, gut microbiota composition, and microglial activation. RESULTSGender-based disparities in lipid metabolism were identified. Changes in {beta}3-adrenergic receptor and neuromodulin-1 expression appear to influence fat regulation and attenuate oxidative stress responses. Subsequently, increased expression of gap junction proteins and activation of the Wnt/{beta}-catenin signaling pathway contribute to metabolic reprogramming and alterations in biochemical kinetics. Gut microbiota analysis demonstrated that, compared to controls, the ICH group exhibited significant dysbiosis and reduced alpha diversity. Further correlation analyses indicated that BPA levels were positively associated with FABP4 and oxidative stress markers, while S100A8 showed a strong dependence on microglial expression. CONCLUSIONThe interplay between lipid metabolism dysfunction and pro-inflammatory cytokines enhances vascular vulnerability. Collectively, BPA exposure, oxidative stress, and microglia-mediated neuroinflammation are significantly associated with an elevated risk of hypertensive ICH. China Clinical Trial Registry registration noticeFrom: China Clinical Trials Registry <chictr@vip.qq.com>+To:guopingwang60a<guopingwang60a@163.com> yunyanshuangfei <yunyanshuangfei@126.com> FUNDINGThis work was supported by the Natural Science Foundation of Shanxi Province (grant no. 201701D121177) Key informationGender-specific differences were observed in lipid metabolism and oxidative stress parameters; BPA exposure was shown to induce lipid metabolic disturbances, promote excessive production of oxidative stress byproducts, and consequently elevate oxidative stress responses; BPA was associated with stress-induced alterations in thyroid hormone function, further exacerbating dysregulation of lipid metabolism and oxidative stress; Fatty acid binding protein 4 (FABP4), a key adipokine implicated in metabolic disorders and adipose tissue inflammation, exhibited a significant positive correlation with serum BPA levels, whereas low levels of triiodothyronine (T3) were negatively correlated with FABP4. These findings suggest that serum FABP4 may serve as a biochemical marker for chronic low-grade adipose tissue inflammation and metabolic dysfunction; Gap junction proteins and the Wnt/{beta}-catenin signaling pathway may contribute to microglial activation and mediate neuroinflammatory responses, nerve injury, and secondary pathological processes in obesity-related cerebral hemorrhage.

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TRPA1 channel activation by synthetic lipid nanoparticles

Milici, A.; Startek, J. B.; Bultynck, G.; Talavera, K.

2026-05-05 pharmacology and toxicology 10.64898/2026.05.03.722497 medRxiv
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TRPA1 is a polymodal ion channel receptor known for its role in nociception. TRPA1 can be activated by local mechanical perturbations in the surrounding plasma membrane (PM) by molecules that insert in the lipid bilayer. Here, we tested whether TRPA1 function can be modulated by lipid nanoparticles (LNPs) while interacting with the target cell plasma membrane. We found that LNP induce irregular Ca2+ transients in heterologous and native TRPA1-expressing cells, which may reflect stochastic LNP-PM interactions. By using different cell types and applying selective and non-selective TRPA1 inhibitors, we revealed that the cytosolic [Ca2+] is elevated transients arise as a result through multiple mechanisms: TRPA1-dependent Ca2+ influx, TRPA1-independent Ca2+ influx, and Ca2+ mobilization from the endoplasmic reticulum. Our results describe a novel, non-canonical TRPA1 activation mechanism by LNPs, that may be relevant in the context of the development of cancer and nasal vaccines.

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Bisphenol-A mediated ubiquitinome alteration triggers PPAR-alpha ubiquitination, affecting trophoblast cell migration

Biswas, A.; Saha, S.; Sarmadhikari, D.; Bisht, K. S.; Asthana, S.; Maiti, T. K.

2026-05-08 biochemistry 10.64898/2026.05.07.723151 medRxiv
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Pregnant women are frequently exposed to various endocrine-disrupting chemicals (EDCs), such as bisphenol A (BPA), causing harm to both the developing placenta and fetus. BPA can promote placental dysfunction by altering key cellular processes such as differentiation, invasion, and migration in trophoblast cells. These cellular processes are also tightly managed by the ubiquitin proteasomal system via maintenance of the ubiquitinated protein pool. However, the BPA-mediated dysregulation of this ubiquitin proteasomal homeostasis is poorly understood. Therefore, we identified 19 deubiquitinases (DUBs) and a dynamic ubiquitinome profile of extravillous trophoblast cells (HTR8/SVneo), which reduced trophoblast cell migration post-BPA exposure. Further investigation using an integrated substrate-ligase-deubiquitinase network shows that BPA binding to PPAR-alpha or indirect regulation of its E3 Ligase MuRF1 and DUB USP5 via BPA resulted in hyper-ubiquitination of PPAR-alpha, triggering its nuclear localization. In the nucleus, the ubiquitinated PPAR-alpha can deregulate its migration-associated target gene expression, causing a reduction in the migration of HTR8/SVneo cells. This physiological alteration of extravillous trophoblast cells (EVTs) through BPA can disrupt placental homeostasis. Hence, we assumed that BPA-induced cellular alteration in EVTs can promote placental defects, which might contribute to adverse pregnancy outcomes.

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Short-chain fatty acids modulate the development and the cell surface molecule expression of dendritic cells by epigenetic regulation

Zhao, W.; Nagata, K.; Akiyama, R.; Yamazaki, Y.; Kouda, H.; Miura, R.; Ishii, K.; Tokita, R.; Ito, N.; Yamasaki, N.; Kaminuma, O.; Nishiyama, C.

2026-05-21 immunology 10.64898/2025.12.23.696329 medRxiv
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BackgroundShort-chain fatty acids (SCFAs) are produced by the gut microbiota as secondary metabolites during fermentation process of dietary fibers. Although SCFAs are beneficial for immuno-related diseases because they regulate the gene expression and functions of myeloid cells, the effects of SCFAs on the development of DCs remain unclear. MethodsWe analyzed the effect of SCFAs on the expression levels of surface proteins and mRNAs, and histone modification in Flt3L-induced bone marrow-derived DCs. ResultsSCFAs, particularly butyrate, regulated the expression of surface molecules on mouse bone marrow-derived dendritic cells (DCs): increases in MHCII, CD86, CD11b, and LPAM-1 (4{beta}7) levels and the ratio of CD11c+/PDCA-1-/B220- conventional DCs (cDCs) to CD11c+/PDCA-1+/B220+ plasmacytoid DCs (pDCs). Experiments using inhibitors of histone deacetylase (HDAC) and Gi proteins, and GPR109A deficient mice indicated that butyrate regulated DCs by suppression of HDACs and not through a stimulatory effect on G protein-coupled receptors. Butyrate and the HDAC inhibitor, trichostatin A (TSA), increased the cDC/pDC ratio, surface LPAM-1 and Itga4 mRNA, while the mRNA level of Itgb7 was not affected by butyrate and was reduced by TSA. ChIP assays showed that butyrate and TSA increased histone acetylation in the Itga4 and Spi1 genes. Furthermore, the butyrate treatment increased the levels of Spi1 mRNA and PU.1 protein and decreased those of Spib/SpiB in DCs. In knockdown (KD) experiments using siRNAs, the gene expression of Itga4 was decreased by KD of Spi1 or Irf8, and cDC/pDC ratio decreased by Spi1 KD. ConclusionsButyrate controls the gene expression and development of DCs through epigenetic regulation and DC-related transcription factors.

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Hydrogen Peroxide induces resistance to DNA damage in a localization and p53 dependent manner.

Keijer, J. P.; Polderman, P. E.; Alcaraz-Sobrevals, P.; van Es, R. M.; Montiel Gonzalez, D.; Kok, R. N. U.; El Baghdadi, S.; Gülersönmez, C.; Stigter, E. C. A.; Vos, H. R.; Burgering, B. M. T.; van Boxtel, R.; Dansen, T. B.

2026-05-15 cancer biology 10.64898/2026.05.13.724825 medRxiv
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Organisms need to be able to adapt to a changing environment in order to survive. The adaptive response invoked by a low dose of a stressor resulting in resistance to high levels of that stressor is known as hormesis and can even lead to lifespan extension of organisms. The exact mechanisms underlying stress-induced hormesis are unknown, although multiple studies pose mitochondria-derived Reactive Oxygen Species (ROS, e.g. H2O2) as an important contributor. Here we used chemo-genetic H2O2 production as a model to study ROS-dependent adaptive responses in a localization-dependent manner. We found that brief, sublethal H2O2 production at the nucleosomes provides p53-dependent resistance to a subsequent high dose of H2O2, whereas mitochondrial H2O2 production, surprisingly, does not. A multi-omics approach revealed that p53-induced hormesis is accompanied by metabolic rewiring that boosts reductive capacity, and that the increased stress resistance can mostly be attributed to its downstream target p21. Importantly, brief p53 stabilization also mounted protection against chemotherapy-induced DNA damage, suggesting that p53-dependent hormesis could be exploited to selectively protect healthy, p53-wildtype tissue from chemotherapy in the treatment of patients with p53 mutant tumors.

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The Conformation of the Complementary Strand and the Deformation of the DNA Groove upon DDB2 Binding Justifies the Different Repair Rates for Cyclobutane Pyrimidine Dimers.

Kedjar, Y.; Hognon, C.; Douki, T.; Dumont, E.; MONARI, A.

2026-05-13 biophysics 10.64898/2026.05.10.724087 medRxiv
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The repair of photo-induced DNA lesions through nucleotide excision repair machinery is still the source of important questions. It has been observed that the repair rate of the different cyclobutane pyrimidine dimers, i.e. the photoproducts induced by dimerization of two {pi}-stacked pyrimidines (T<>T, T<>C, C<>T, C<>C), depends on the nucleobases involved in the lesion. TT derivatives (T<>T) are removed more slowly than those containing cytosine, especially in 5. Using all-atom molecular dynamics simulations and free-energy calculations, we demonstrate that the variation of the repair rate observed in human skin and in cultured cutaneous cell is associated to the recognition of the four lesions by the DDB2 protein moiety, and more specifically by the differential structural deformation induced on the complementary strand. Indeed, while C<>C and C<>T induce a larger deviation on the groove parameters, T<>T and T<>C, instead, affect DNA structure to a lesser extent. less affected. These effects then hamper differentially the downstream recruitment of the repair complexes. The observed DNA deformation correlates with the experimental repair rate and provides a structural rationale for the different repair rates of CPD by nucleotide excision repair machinery. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=105 SRC="FIGDIR/small/724087v1_ufig1.gif" ALT="Figure 1"> View larger version (43K): org.highwire.dtl.DTLVardef@cf6b6dorg.highwire.dtl.DTLVardef@195e35forg.highwire.dtl.DTLVardef@1829296org.highwire.dtl.DTLVardef@165baba_HPS_FORMAT_FIGEXP M_FIG C_FIG

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A2 and A1B in vitro milk digests: effects on in vitro leaky gut model and adipose cells

Perugini, J.; Bendinelli, P.; Scopini, E.; Galli, C.; Cattaneo, S.; Bonfatti, V.; Cinti, S.; Finco, A.; De Noni, I.; Giordano, A.; Ferraretto, A.

2026-05-13 molecular biology 10.64898/2026.05.09.723973 medRxiv
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Obesity is associated with chronic low-grade systemic inflammation of adipose tissue and is often linked to intestinal epithelial barrier (IEB) dysfunction. The present study aimed to evaluate the effects of in vitro gastrointestinal digests of bovine milk containing A1B or A2 {beta}-casein variants on leaky IEB and adipocyte inflammation. Digests of A1B (DA1B) and A2 (DA2) milk were administered to an in vitro Caco-2/HT-29 intestinal cell co-culture mimicking a leaky gut. Intestinal absorbed fractions derived from A1B (MA1B) and A2 (MA2) were administered to hMADS adipocytes. DA1B and DA2 did not modify intestinal permeability, either in the absence or the presence of inflammation. DA1B reduced Claudin-1 mRNA, as well as zonula occludens-1 mRNA and protein expression. Both DA1B and DA2 increased interleukin-8 expression, but only DA1B increased tumor necrosis factor-. In human adipocytes, MA1B, and to a lesser extent MA2, increased the expression of pro-inflammatory markers monocyte chemoattractant protein-1 and interleukin-6, while reducing adiponectin levels. DA2 preserved in vitro leaky IEB integrity and exhibited a lower inflammatory potential in both leaky gut and adipocytes compared to DA1B. This study is the first to establish a link among A2 milk, leaky gut syndrome, and obesity.

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Crude Fucus vesiculosus fucoidan demonstrates superior SARS-CoV-2 antiviral activity compared to its pure form: binding kinetics and functional studies

Dudek, A.; Janapatla, R. P.; Chen, C. L.; Chiu, C. H.

2026-05-12 biochemistry 10.64898/2026.05.07.723385 medRxiv
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Fucoidans have been widely reported to show SARS-CoV-2 antiviral activity. In this study, we observed a striking difference in the inhibitory potency between two commercially available fucoidans: Fucus vesiculosus crude (Fvc) and pure (Fvp). SEC-MALS analysis revealed two molecular weight populations for Fvc (1098 kDa, 58.58 kDa) and one for Fvp (40.48 kDa). At micromolar concentrations of fucoidans, the binding affinities (KDs) of Fvc_1098 (223 nM) and Fvc_58 (4.27 {micro}M) for the amine-biotinylated SARS-CoV-2 receptor binding domain (RBD) were higher than that of Fvp (76.5 {micro}M). At nanomolar concentrations, binding was observed only to the Avi-tag-, but not amine-biotinylated RBDs, suggesting better accessibility of their binding sites. The association rates (kon) were faster for Fvc than for Fvp. Similarly, affinities of Fvc_1098 (23.4 nM) and Fvc_58 (4.48 M) for ACE2 were greater than that of Fvp (66.8 M), indicating that Fvc can bind directly to both RBD and ACE2. Fvc demonstrated enhanced inhibitory potency (IC50 = 58 g/mL) compared to Fvp (IC50 > 239 g/mL) in the pseudovirus entry assay and did not induce cytotoxicity in HEK293T cells. In conclusion, crude fucoidan with high fucose content and high molecular weight shows promising antiviral activity.

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Cholesteryl Esters Modulate Lipid Droplet Rigidity and Monolayer Organization during Liver Cancer Progression

Campbell, O.; Leal, C.; Monje, V.

2026-05-05 biophysics 10.64898/2026.05.01.722229 medRxiv
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In mammalian cells, lipid monolayers support the integrity of lipid droplets (LDs), organelles that function as storage for neutral lipids. Liver-targeting illnesses such as liver cancer interrupt normal LD metabolism and prompt changes in the chemical content of these organelles, which can have effects on structural and organizational behavior of the lipids. In LDs, liver cancer induces concentric crystalline phases of cholesteryl esters (CEs) and triglycerides near the NL-monolayer interface, which become more pronounced as CE concentration increases. Yet, there is little known about how this phenomenon may link to persistence of undigested LDs in liver cancer patients. To shed light on this, all-atom molecular dynamics simulations were used to model LD micropipette aspiration experiments and gain insight into the effect of CE concentration on partitioning, structural, and mechanical properties of LDs. We successfully model micropipette aspiration by application of constant surface tension laterally, which stretches lipid bilayers and monolayers as the magnitude increased. The results show increased phospholipid packing due to insertion of CE fatty tails into the monolayer. Increasing CE concentration induces a non-linear change in surface packing defects on the LDs, notable rigidification, and stiffness. Taken together, these insights improve our understanding of the physical properties at the LD monolayer-core interface during liver cancer progression.

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Fabrication of the high-resistance patch-clamp pipettes for mitochondrial electrophysiological studies using optimized two step method

Pavlov, E.; Mohamed, N.; Artemchuk, O.; Rabieh, S.; Peixoto, P.; Bromage, T.

2026-05-08 biophysics 10.64898/2026.05.05.723071 medRxiv
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The patch-clamp experimental technique is widely used to study the electrical properties of ion channels in biological and artificial lipid membranes. The key to the high quality of the experiments is the manufacturing of glass pipettes that provide highly electrically resistant contact between the edge of the pipette tip and the lipid bilayer. Preparation of the pipettes is particularly challenging for studies of the mitochondrial membranes due to the need for very small pipette tip sizes. Here, we present a robust procedure for producing pipettes suitable for experiments with native mitochondrial membranes. This procedure involves a two-step approach: initial fabrication of relatively large glass micropipettes using a standard micropipette puller, followed by tip refinement using a microforger to achieve smooth glass surface and reduced opening size. Pipette tip diameters and surface structure were examined using field emission - scanning electron microscopy (FE-SEM) imaging to assess the effects of variable parameters on pipette geometry and size. The resulting pipettes were validated in patch-clamp recording of the mitochondrial inner membranes. This approach enables the reproducible production of optimized pipettes for mitochondrial patch-clamp experiments, improving the quality and throughput of electrophysiological recordings of the mitochondrial ion channels.

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Functional Analysis of cha Genes Identifies ChaC as a Glutathione-Degrading Enzyme Rather Than a Sodium Transport Regulator

Sawada, H.; Ohkama-Ohtsu, N.; Ito, T.

2026-05-19 biochemistry 10.64898/2026.05.15.725350 medRxiv
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Glutathione (GSH) is a tripeptide that plays essential roles in redox regulation and stress responses across organisms. In Escherichia coli, the GSH-specific {gamma}-glutamyl cyclotransferase (ChaC) has been characterized biochemically, yet its physiological role remains unclear. Moreover, ChaC has been annotated as a regulator of the Na/H antiporter ChaA based on its genomic association, although experimental evidence supporting this function is limited. In this study, we investigated whether chaC and its co-transcribed gene, chaB, are involved in sodium transport or GSH metabolism. Gene expression analyses revealed that chaA, chaB, and chaC are upregulated under salt stress. Functional analyses using deletion mutants showed that loss of chaA reduced salt tolerance, whereas deletion of chaB enhanced tolerance and decreased intracellular sodium levels. In contrast, deletion of chaC had no significant effect on salt tolerance or sodium accumulation. Overexpression of cha genes further indicated that chaA, but not chaB or chaC, contributed to salt tolerance. Importantly, overexpression of chaC significantly reduced intracellular GSH levels, whereas chaB overexpression had no effect. These results indicate that ChaC primarily functions in GSH degradation rather than in cation transport, and that ChaB does not participate in GSH metabolism. Our findings clarify the distinct physiological roles of ChaC and ChaB and provide new insight into bacterial physiology regarding GSH metabolism and ion transport in E. coli.

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Elucidation of the anti-inflammatory mechanism of isoliquiritigenin from Glycyrrhiza uralensis using activity-based protein profiling

Sakai, H.; Chung, M. H.; Nakaya, T.; Ohbuchi, K.; Isobe, Y.; Arita, M.; Tsumagari, K.; Imami, K.; Hirokawa, T.; Tsugawa, H.

2026-05-08 biochemistry 10.64898/2026.05.05.722967 medRxiv
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Glycyrrhiza uralensis is a widely used medicinal plant present in more than 70% of Kampo formulations in Japan owing to its diverse pharmacological activities, including immunomodulatory, antitumor, and antioxidant effects. Isoliquiritigenin (ILG), a major chalcone constituent of G. uralensis, exhibits anti-inflammatory activity; however, its molecular mechanism remains unclear. Here, we employed an activity-based protein profiling approach to identify the molecular targets of ILG. Given that the ,{beta}-unsaturated carbonyl moiety of ILG can covalently react with reactive cysteine residues via nucleophilic addition, we used an iodoacetamide-based probe to globally profile cysteine-reactive proteomes. The comparative analysis between ILG- and vehicle-treated RAW 264.7 macrophages identified cysteine 65 (Cys65) of lipocalin-type prostaglandin D2 synthase (L-PGDS) as a potential covalent target. ILG treatment did not alter L-PGDS expression levels, indicating that reduced probe labeling reflects direct covalent competition rather than changes in expression. Consistently, ILG significantly suppressed prostaglandin D2 (PGD2) production, comparable to the selective L-PGDS inhibitor AT-56. Although both ILG and AT-56 reduced interleukin-6 expression, ILG exerted a stronger inhibitory effect. Our results demonstrate that covalent inhibition of L-PGDS and subsequent suppression of PGD2 production represent a key mechanism underlying the anti-inflammatory activity of ILG.

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Antioxidant capacity of Catechinopyranocyanidins derived from adzuki beans

Kawabata, R.; Hagiwara, I.; Komizo, N.; Inaba, Y.; Matsui, T.; Ito, T.

2026-05-19 biochemistry 10.64898/2026.05.15.725587 medRxiv
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Catechinopyranocyanidins (Cpcs) which consist of diastereomers A and B are pigments derived from adzuki beans and are compounds in which the catechin and cyanidin skeletons are condensed to a pyrano ring. While catechins and anthocyanidins possess high antioxidant capacity, the physiological functions of Cpcs remains unclear. In this study, the antioxidant capacity of Cpcs was evaluated by in vitro antioxidant assays and by assessing their cytoprotective activity against oxidative stress in normal human dermal fibroblasts (NHDFs). Antioxidant capacity based on the hydrogen atom transfer (HAT) mechanism, as assessed by the ORAC assay revealed that Cpcs exhibit 14.1 mol TE/mol (Trolox equivalent antioxidant capacity: TEAC). Meanwhile, capacity based on the single electron transfer (SET) mechanism, as assessed by the DPPH, ABTS and CUPRAC assays revealed, they exhibit 2.1-3.6 mol TE/mol. Since TEAC value of Cpcs demonstrated by the HAT based mechanism higher than its SET based oxidative capacity suggesting that the antioxidant capacity of Cpcs is driven by the HAT mechanism. In cell culture experiments, Cpcs ameliorate cell toxicity in rotenone-induced injury model, suggesting to cytoprotective activity against mitochondrial dysfunction-dependent apoptosis. These results reveal novel physiological functions of Cpcs which may serve as a design guideline for elucidating in vivo dynamics based on antioxidant mechanisms.

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Increased chromatin accessibility following 1α,25-dihydroxyvitamin D3 treatment in human endometrial stromal cells

Yi, M.; Bostan, H.; DeMayo, F. J.

2026-05-09 molecular biology 10.64898/2026.05.06.723064 medRxiv
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Vitamin D signaling has recognized roles in female reproductive physiology, but its effects at the chromatin level in endometrial stromal cells are still unclear. Here, we investigated how the active form of vitamin D, 1,25-dihydroxyvitamin D3, or calcitriol, influences the accessible chromatin landscape of human endometrial stromal cells. Assay for transposase-accessible chromatin using sequencing (ATAC-seq) was performed on T-HESCs treated with either a vehicle or 1,25(OH)2D3. Ligand treatment increased overall chromatin accessibility, shown by higher ATAC-seq signal intensity, while causing only minor changes in the total number of called peaks. Peak annotation revealed that accessible regions were spread across both promoter-proximal and distal genomic areas. Integrating this data with CUT&RUN and RNA sequencing showed that most vitamin D-responsive cistromic modifications and transcripts were linked to nearby open chromatin, though fewer were associated with regions that were significantly differentially accessible. These results suggest that 1,25(OH)2D3-dependent transcription mainly occurs within a permissive, pre-accessible chromatin environment. This study offers new evidence that active vitamin D influences the epigenomic landscape of human endometrial stromal cells, establishing the chromatin-based molecular response to a chemically-defined VDR ligand, 1,25(OH)2D3, relevant to stromal differentiation and preparation for decidualization. HighlightsO_LIFirst evidence suggesting the direct impact of active vitamin D, 1,25-dihydroxyvitamin D3, 1,25(OH)2D3, enhanced the signal intensity of chromatin accessibility in human endometrial stromal cells C_LIO_LIMost accessible chromatin regions were shared between vehicle and ligand-treated human endometrial stromal cells C_LIO_LI1,25(OH)2D3-responsive transcription occurs largely within pre-accessible chromatin in human endometrial stromal cells C_LIO_LIAssay for transposase-accessible chromatin sequencing (ATAC-seq) defines a chromatin-level pharmacologic response to a chemically defined VDR ligand in human endometrial stromal cells C_LI

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Cross Dataset Transcriptomic Analysis Identifies Oxidative Stress Inflammation Gene Networks Modulated by Nutrigenomic Interventions in Parkinson Disease

Rafiee, M.; Abaj, F.; Mahdevar, M.; Rashidian, A.; Ghaedi, K.; Ghiasvand, R.

2026-05-09 bioinformatics 10.64898/2026.05.05.723100 medRxiv
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Inflammation and oxidative stress (OS) are key to Parkinsons disease (PD). We performed a cross-dataset integrative transcriptomic analysis to identify OS- and inflammation-related hub genes persistently dysregulated in PD and to evaluate their response to nutrigenomic interventions using publicly available datasets. Four GEO datasets (GSE7621, GSE20141, GSE20146, GSE49036) were analysed to identify differentially expressed genes (DEGs), which were intersected with GeneCards OS-inflammation gene sets. Functional enrichment analyses, including gene ontology (GO), pathway over-representation analysis (ORA), and protein-protein interaction (PPI) analysis, were used to identify key pathways and hub genes. Gene-food bioactive compound (FBC) association was explored by integrating PD signatures with nutrigenomic profiles from NutriGenomeDB. We identified 183 DEGs in PD, enriched in synaptic, dopaminergic, OS, and inflammatory pathways. Intersection analysis yielded 26 OS-inflammation-related genes and 10 central regulators, including TH, DDC, SNCA, LRRK2, HSPB1, and HSPA1B. revealed opposing transcriptional patterns, with several FBCs suppressing stress-related genes and upregulating dopaminergic markers such as TH, GCH1, and DDC. Overall, this integrative analysis highlights OS-inflammation gene networks in PD and identifies candidate diet-gene interactions that warrant further experimental validation

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A lipid-binding protein in black-legged tick saliva selectively recognizes Borrelia burgdorferi lipids

Shi, W. O.; MacMackin-Ingle, T.; Perez, M. W.; Griffith, W. P.; Chen, L.; Seshu, J.; Renthal, R.

2026-05-07 biochemistry 10.64898/2026.05.04.722819 medRxiv
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A proteomic analysis of Ixodes scapularis nymph saliva identified 252 proteins, including six tubular lipid-binding proteins (TULIPs). Comparing nymphs fed on mice that were uninfected or infected with Borrelia burgdorferi, twelve salivary proteins showed significant differences in the amounts detected, including XP_040079658.2, which we refer to as TULIP2. Considering the known immunity-related functions of some TULIPs, we expressed and purified TULIP2 from Escherichia coli and analyzed its interaction with B. burgdorferi lipids. The purification of TULIP2 from E. coli presented many obstacles, due to insolubility, which is consistent with previous reports from studies of other TULIP family members. The binding results showed specificity for B. burgdorferi lipids, with evidence for cholesteryl {beta}-galactoside as a major binding target. Molecular modeling of TULIP2 did not show any strong lipid binding sites. We used molecular dynamics simulation of TULIP2 to explore its conformational landscape by thermal unfolding. The earliest unfolding intermediate opened a hydrophobic pocket to which cholesteryl {beta}-galactoside was predicted to bind strongly. We propose that a specific lipid bilayer interaction with TULIP2 triggers the opening of the ligand-binding site.