Biochemical and Biophysical Research Communications

Every known life form senses and reacts to mechanical forces. These mechanical stimuli can be converted into electrical signals by mechanically gated ion channels, a transduction cascade pivotal to numerous physiological functions including touch, hearing, mechanical pain, circulation, gastrointestinal function, and mechanical loading in various tissues. Despite continuous efforts, numerous mechanically gated ion channels with the mechanotransduction process underlying these physiological functions remain unidentified. Here, we focused on the transmembrane channel-like (TMC) protein family expressed in the cultured cells to identify those with potential mechanosensitive activity. Remarkably, in contrast to human TMC1/2 (HsTMC1/2), human TMC3-8 (HsTMC3-8) proteins are localized to the plasma membrane when heterologously expressed in the cultured cells. Further experiments revealed that mechanical poking stimuli can effectively activate HsTMC3-8. In addition, HsTMC3-8 induced stretch-activated currents and elicited well-resolved single-channel activities in response to negative pressure stimulation. The mutants near the putative pore region altered reversal potentials (Erev) of HsTMC3-8, suggesting that TMC3-8 are likely pore-forming subunits of ion channels. In summary, we proposed that TMC proteins are the largest mammalian mechanically gated ion channel family.

Eukaryotic translation initiation is tightly regulated by interactions among translation initiation factors (eIFs) that ensure accurate start codon selection. The translation regulator, eIF5 mimic protein 1 (5MP1) contributes to this process by competing with eIF5 for binding to eIF2, thereby increasing the stringency of translation initiation. Despite its important regulatory role and emerging involvement in tumorigenesis, structural information on human 5MP1 remains limited. Here, we report the near-complete backbone and partial side-chain NMR resonance assignments of the C-terminal domain of human 5MP1 (residues 250-419), carrying a W404E substitution that disrupts dimerization. The WT protein forms a dimer at NMR concentrations, which increases the effective size of the protein and also causes disappearance of peaks corresponding to aminoacids at the dimer interface due to conformational exchange. Backbone resonance assignments were completed for 96.4% of the non-proline residues. Secondary structure was analyzed using Chemical Shift Index (CSI) and compared with the AlphaFold structural model. Regions of disagreement between the experimental and computational secondary structure assignments were further examined using 15N-NOESY-HSQC spectra, allowing experimental validation of local structural features. While the AlphaFold model accurately reproduces the overall fold of the 5MP1 C-terminal domain, several localized discrepancies were identified, particularly near the N- and C-terminal regions of the domain, where experimental NMR data support alternative secondary structure assignments. These resonance assignments and experimentally validated structural features provide a foundation for future investigations of the molecular interactions, dynamics, and functions of 5MP1 in translation initiation.

Cholesterol is a key component of eukaryotic cell membranes, promoting membrane stability and modulating the function of many membrane proteins, including ion channels. In our previous work using purified human voltage-gated proton channel proteins, we showed that cholesterol inhibits the hHv1 channel by altering the conformational dynamics of its S4 segment, the key element that senses membrane voltage to control proton permeation. In the present work, we examined the effects of cholesterol analogs and potential sites in the hHv1 channel mediating cholesterol inhibition using site-directed mutagenesis and docking simulations. Our results showed that desmosterol, the immediate precursor of cholesterol, markedly attenuates cholesterol inhibition. Using single-molecule Fluorescence Resonance Energy Transfer (smFRET), we showed that desmosterol attenuates cholesterol inhibition by promoting the intermediate and open state conformations of the S4 segment. Moreover, we identified multiple residues in the hHv1 channel that are critical for cholesterol inhibition, including Y141A in the S2 segment, which reduces cholesterol inhibition by nearly 3-fold. Our smFRET results showed that the Y141A mutation promotes the intermediate conformation in the S4 segment, which underlies the attenuation of cholesterol inhibition. Consistently, docking simulations also revealed multiple residues spanning the transmembrane domain, rather than clustered within a single localized pocket. Our work identified the key molecular determinant in the hHv1 channel that mediates cholesterol inhibition and also provided a mechanism linking the conversion between demosterol and cholesterol by DHCR24 to pH homeostasis in many cells, such as phagocytes, cardiomyocytes, neurons and microglial cells.

Long noncoding RNAs encode for microproteins that regulate cellular functions. Small regulatory peptide of amino acid response (SPAR) is a microprotein in the lysosome that responds to amino acid availability of the cell. In this study, we investigated the interactions between SPAR and SLC38A9, a lysosomal amino acid transporter and receptor involved in the mechanistic target of rapamycin 1 (mTORC1) pathway. We found that SPAR binds SLC38A9 and inhibits arginine transport in SLC38A9. Moreover, the downstream recruitment of Rag GTPases is also inhibited when SPAR is present in SLC38A9 liposomes. Docking model shows potential interactions between SPAR and SLC38A9. Together, these findings reveal the mechanism of mTORC1 inhibition through microprotein SPAR and illustrates the power of non long coding RNAs in altering cellular functions. Statement of SignificanceMicroproteins encoded from long noncoding RNAs are emerging as critical regulators of many pathways. This study investigates a novel mechanism of SPAR microprotein that directly regulates the mechanistic target of rapamycin complex1 (mTORC1) signaling pathway through the lysosomal amino acid transporter SLC38A9. SPAR blocks both arginine transport and the downstream recruitment of Rag GTPases. These findings provide critical results in how SPAR controls cellular amino acid availability, while broadly highlighting the powerful regulatory mechanism of microproteins in cellular processes.

MLLT1 (also named ENL) is a chromatin reader protein whose encoding gene was originally identified as a chromosomal translocation partner with MLL(KMT2A) in acute leukemia. However, its role in normal hematopoiesis has not been investigated. This study uncovers a critical role of Mllt1 in normal B cell lymphopoiesis. We found Mllt1 to be essential for early B lymphocyte development using a conditional Mllt1 knockout mouse model that we developed. A significant decrease of bone marrow B-lineage progenitors, splenic transitional B cells and peripheral blood B cells were observed in Mllt1del mice compared to control Mllt1fl/fl mice. Similarly, Mllt1 deletion in in vitro cultured B-enriched progenitor cells from Mllt1fl/fl; Rosa26CreERT2/+ mice resulted in reduced B cells, demonstrating the cell-intrinsic role of Mllt1 in this process. Direct MLLT1 target genes including Il7r and critical B-lineage transcription factors, Ebf1 and Pax5, were decreased following Mllt1 deletion. Gene set enrichment, gene ontology, and functional analyses of Mllt1-deficient cells showed significant alterations related to B cell development, critical relevant signaling pathways, DNA replication, and mitochondrial function. In vitro complementation with MLLT1 rescued the B cell phenotype observed with endogenous Mllt1 deletion; however, specific MLLT1 YEATS domain mutants lacking chromatin reader and RNA-binding functions were unable to rescue the phenotype. Taken together, our research demonstrates a previously unappreciated role for MLLT1 as critical for maintenance of B cell lymphopoiesis.

The lack of effective anti-JEV therapy possesses significant challenge to control JEV. {beta}-catenin, a key mediator of Wnt signaling pathway regulates different viral replication and host immune responses. However, its role in JEV infection remains to be elucidated. Thus, the current study focused on evaluating iCRT-14, a specific {beta}-catenin inhibitor, against JEV. Treatment with iCRT-14 following JEV infection resulted efficient reduction in viral progeny release, viral RNA and protein levels in Huh7 and HEK293T cells. Further, active and total {beta}-catenin, Cyclin D-1 and GSK3-{beta}, the other key pathway players were also modulated in infected and inhibitor treated cells. Moreover, iCRT-14 showed an IC of 4.56 in Huh7 cell and maximal inhibition at the early stages of the JEV life cycle. Interestingly, the overexpression of {beta}-catenin in both the cells and siRNA-mediated {beta}-catenin knockdown (in Huh7 cells) significantly abrogated JEV replication, as evidenced by decreased viral titers, viral protein expression, and viral as well as total RNA levels. Moreover, the reduction in extracellular (84%) and intracellular (60%) viral titers following iCRT-14 treatment highlights its role in impairing JEV infection. Further, in silico molecular docking and co-immunoprecipitation studies demonstrated interactions between {beta}-catenin and the JEV NS5 and E proteins. Collectively, these findings suggest that optimum level of {beta}-catenin is required for efficient JEV infection, highlighting its potential as a target for designing host-directed control strategies to regulate viral infection.

Background: Viral myocarditis presents a significant burden of disease, particularly among children and young adults. However, clinical guidelines and treatment strategies for pediatric patients are derived from those for adult patients due to a lack of pediatric data. Current animal models of viral myocarditis use adult mice, so conclusions from these models cannot necessarily be extrapolated to the pediatric population. We sought to develop a juvenile mouse model of myocarditis to examine differences between these two distinct clinical populations. Methods: Male and female BALB/c 3-4-week-old 'juvenile' and 8-week-old 'adult' mice were infected intraperitoneally with 103 PFU of heart-passaged coxsackievirus B3. Sera was used to evaluate testosterone and estradiol levels. Cardiac histological evaluations included overall inflammation, fibrosis, and specific cell-type infiltration. RNA was extracted from cardiac tissue and evaluated for changes in gene expression of cell-type markers, complement components, and NLRP3 inflammasome components. Results: Juvenile mice exhibited more severe inflammation than adult mice but no sex differences in overall inflammation. Juvenile mice demonstrated increased infiltration of CD11b+ cells, F4/80+ cells, and CD3+ T-cells vs. adults. Inflammasome genes NLRP3 and caspase-1 were significantly increased in juvenile compared with adult myocarditis. Conclusions: This paper is the first to describe a juvenile mouse model of coxsackievirus B3 myocarditis and provides a direct comparison to a translational adult mouse model. Juvenile mice had greater cardiac inflammation than adults. This model replicates clinical populations and provides a valuable tool to study age as a factor in the pathogenesis of myocarditis.

In TMPRSS2 fusion-positive prostate cancer, ERR is involved in regulation of ERG and promotes the androgen receptor independent signaling in the cancer progression. The ERR binds to the ERREs (estrogen-related receptor response elements) present at -5042 bp of the TMPRSS2- promoter and enhances the ERG overexpression that causes prostate cancer progression. To dissect the structural basis of the ERR recognition to the TMPRSS2 promoter DNA, we have purified the full-length ERR (ERRFL), NTD deleted construct (ERR{Delta}NTD), and the DNA-binding domain (ERRDBD) proteins and performed the binding analysis with 30 bp TMPRSS2-promoter DNA (5' -AGTCCAAGGTCGGTGGATC ACAAGGTCAGG-3'). Circular dichroism analysis showed that all three ERR proteins adopt native secondary structures. DNA binding induced subtle changes in the secondary structures, while enhancing the thermal stability (Tm) of all ERRa proteins. Binding analysis showed that ERRDBD bound weakly to the DNA, whereas ERRFL and ERR{Delta}NTD exhibited substantially higher affinities ~120-fold and ~131-fold than ERRaDBD, respectively. Small-angle X-ray scattering (SAXS) analyses revealed a dimeric ERRFL structure and an ERRFL-DNA complex (2:1) structure in solution and fitted well with Alpha Fold model of apo and DNA bound complex of ERRFL. Furthermore, 100 ns dynamics simulations on apo and DNA-bound ERRa proteins showed that all proteins remained structurally stable, with flexibility largely confined to loop regions of ERRa proteins. Our biophysical, DNA binding and structural analyses have revealed the mechanism involved in ERR recognition of the TMPRSS2- promoter DNA, which provides insight into ERR-mediated transcriptional regulation and development of anticancer drugs against ERR-driven prostate cancer.

AimThe present study investigated the significance of iron in regulating megakaryopoiesis, by a diet-based intervention in an in-vivo model. MethodsMale C57BL/6 mice, aged 4-5 weeks were fed on varying iron diets. Following sacrifice, blood samples collected in EDTA tubes were used to analyse haematological parameters, and iron content of liver and spleen was assessed by biochemical analyses. Megakaryocyte-erythroid progenitors (MEPs) were isolated from bone marrow by magnetic bead-based selection. RNA isolated from bone marrow cells and MEPs were used for gene expression analyses, and RNA Sequencing to identify differentially expressed genes (DEGs) and associated pathways. ResultsMice fed on an iron-deficient diet had reduced hepatic iron content after 5 weeks (p < 0.01), while both the hepatic and spleen iron content increased after 3 weeks in mice on an iron-rich diet (p < 0.05) and developed iron overloading. Hb and RBC counts increased (p < 0.05) in iron-rich mice and decreased in iron-deficient mice (p < 0.05), which also showed elevated platelet counts (p < 0.01). This may be explained by increased expression of Gata1, Tal1 (p < 0.01) Mds1 and Pdpk1 (p < 0.05) in bone marrow cells from iron-deficient mice. MEPs isolated from these mice showed elevated expression of genes associated with megakaryocytic differentiation, platelet functions, and genes encoding TGF-{beta}R1 and Smad 2,3 and 4. ConclusionsIron deficiency may activate TGF-{beta} signalling and downstream Smad-mediated transcriptional programs within MEPs. This may promote a shift in lineage commitment towards megakaryopoiesis through elevated expression of megakaryopoiesis related genes.

Hutchinson-Gilford Progeria Syndrome (HGPS) is a rare genetic condition characterized by features of accelerated aging, with a life expectancy of less than two decades. HGPS is commonly caused by a point mutation in the LMNA gene which codes for lamin A, a vital component of the nuclear lamina. The HGPS mutation activates a cryptic splice site and leads to production of a truncated, farnesylated form of lamin A referred to as "progerin." Progerin is also produced in small amounts in healthy individuals and has been implicated in normal aging. HGPS is associated with an accumulation of genomic DNA double-strand breaks (DSBs), and alterations in DSB repair. DSB repair in mammalian cells normally occurs by either homologous recombination (HR), an accurate, templated form of repair, or by DNA end-joining (EJ), a non-templated rejoining of DNA ends. EJ is error-prone, although a portion of EJ events occurs precisely with no alteration to joined sequences. Previously, we reported that over-expression of progerin increased EJ relative to HR and decreased the precision of EJ. In our current work, we designed a novel model experimental system using derivatives of thymidine kinase (tk)-deficient mouse fibroblasts and incorporating a loss-of-function assay to further explore progerins impact on EJ. We established cell lines containing an integrated copy of a functional herpes tk gene with an embedded recognition site for endonuclease I-SceI. We examined EJ at the nucleotide level following induction of a DSB within the tk gene by expression of I-SceI and subsequent selection for cells that lost tk gene function. Comparison of EJ products recovered from cells expressing progerin versus from cells not expressing progerin revealed that progerin expression provoked larger DNA deletions associated with DSB repair as well as recovery of multiple repair products from individual cells, suggesting progerin impedes re-joining of DNA ends.

Uncoupling protein 1 (UCP1) mediates thermogenesis in brown adipose tissue. Whether human-UCP1 shares the bioenergetic properties established for rodent UCP1 (innate uncoupling, GDP sensitivity, fatty acid (re)activation) is not known. Therefore, we expressed human and mouse UCP1 in mouse liver, using adeno-associated viral vectors, and characterized their properties in isolated liver mitochondria. Both UCP1s induced marked innate uncoupling, characterized by increased substrate-supported respiration and decreased membrane potential, in the absence of exogenous fatty acids. Mouse-UCP1 in liver retained the classical regulatory properties of native brown-fat UCP1, including potent inhibition by GDP and reactivation by oleate. In contrast, human-UCP1 was only weakly inhibited by GDP but was strongly responsive to fatty acids. However, ATP potently inhibited human-UCP1, with an apparent IC of {approx}0.4 mM compared with {approx}1.4 mM for GDP, and ATP markedly decreased the sensitivity of human-UCP1 to oleate (re)activation. Despite substantial UCP1-mediated uncoupling, oxidative phosphorylation capacity and mitochondrial OXPHOS protein levels were preserved. Molecular dynamics simulations suggested a structural basis for the species difference. GDP formed persistent interactions with F88 in mouse-UCP1, an interaction absent at the corresponding S88 residue in human-UCP1. In-silico substitution of F88 by serine reduced GDP interaction at this site. Thus, human and mouse UCP1 share innate thermogenic activity but differ fundamentally in nucleotide regulation. The F88/S88 difference may contribute to the preferential GDP sensitivity of mouse-UCP1, whereas ATP provides effective nucleotide control of human-UCP1.

Ependymal (E1) cells, with their tufts of [~]50 motile cilia, line the walls of the brain ventricles and help propel the cerebrospinal fluid (CSF). The CSF is rich in signaling molecules, but the cellular targets that detect these signals and their function remain unknown. Here, we describe a distinct population of ependymal cells (E2) in the forebrain of mice and humans, the majority having only 1 or 2 cilia. These cilia were motile, but unlike E1 cells cilia, their pattern of motility and high expression of Arl13b and Inpp5e suggest a sensory function. E2 cells were characterized by an enormous, donut-like basal body that contained an increased number and size of subdistal appendages. In mice, E2 cells were mostly born in the embryo, but completed their differentiation in juveniles and young adults; they were found at higher densities in regions of high CSF flow and neurogenesis. E2 cilia contained the G protein-coupled receptor Smoothened, which accumulated in their cilia upon exposure to Sonic Hedgehog (Shh). Together, these findings identify E2 cells as a novel CSF-sensing ependymal cell type and provide a cellular target for the CSF signaling.

This study aims to investigate the cardioprotective effects of 4-Hydroxybenzaldehyde (4-HBA) against isoproterenol (ISO)-induced cardiac fibrosis and to elucidate the underlying mechanisms. In vivo, cardiac fibrosis was induced in C57BL/6 mice by subcutaneous injection of ISO, and the mice were treated with 4-HBA or a TGF-{beta} inhibitor. Assessments using echocardiography, histopathology, and Western blotting demonstrated that 4-HBA significantly alleviated ISO-induced cardiac dysfunction, reduced collagen deposition, and attenuated apoptosis in mice. Mechanistically, 4-HBA inhibited TGF-{beta} expression and Smad2/3 phosphorylation. In vitro, ISO was applied to cardiomyocytes (HL-1) and cardiac fibroblasts (MCFs), with or without 4-HBA or TGF-{beta} inhibitor intervention. The results showed that 4-HBA suppressed HL-1 apoptosis and fibroblast proliferation, and significantly reduced the expression of extracellular matrix genes, TGF-{beta} levels, and Smad2/3 phosphorylation in MCFs. These findings indicate that 4-HBA reduces myocardial injury while targeting the TGF-{beta}/Smad2/3 pathway to attenuate cardiac fibrosis, highlighting its potential as a therapeutic agent for fibrotic cardiomyopathy.This study aims to investigate the cardioprotective effects of 4-Hydroxybenzaldehyde (4-HBA) against isoproterenol (ISO)-induced cardiac fibrosis and to elucidate the underlying mechanisms. In vivo, cardiac fibrosis was induced in C57BL/6 mice by subcutaneous injection of ISO, and the mice were treated with 4-HBA or a TGF-{beta} inhibitor. Assessments using echocardiography, histopathology, and Western blotting demonstrated that 4-HBA significantly alleviated ISO-induced cardiac dysfunction, reduced collagen deposition, and attenuated apoptosis in mice. Mechanistically, 4-HBA inhibited TGF-{beta} expression and Smad2/3 phosphorylation. In vitro, ISO was applied to cardiomyocytes (HL-1) and cardiac fibroblasts (MCFs), with or without 4-HBA or TGF-{beta} inhibitor intervention. The results showed that 4-HBA suppressed HL-1 apoptosis and fibroblast proliferation, and significantly reduced the expression of extracellular matrix genes, TGF-{beta} levels, and Smad2/3 phosphorylation in MCFs. These findings indicate that 4-HBA reduces myocardial injury while targeting the TGF-{beta}/Smad2/3 pathway to attenuate cardiac fibrosis, highlighting its potential as a therapeutic agent for fibrotic cardiomyopathy.

Introduction: Central regulation of energy homeostasis is essential for balancing lipid storage and reproductive investment; however, the hypothalamic factors governing this trade-off remain incompletely defined in birds. Neurosecretory protein GM (NPGM), an 83-amino acid hypothalamic factor, was investigated for its role in energy allocation during sexual maturation in Japanese quail (Coturnix japonica). Methods: Male and female quails at the onset of sexual maturation received chronic intracerebroventricular administration of NPGM for 13 days via osmotic pumps, during which their body mass, food intake, and water intake were monitored daily. At the endpoint, peripheral tissue and muscle masses, serum metabolite levels (glucose, fatty acids, triglycerides, testosterone, and 17{beta}-estradiol), hepatic triglyceride content, and gene expression profiles of hypothalamic feeding/reproductive genes and hepatic/adipose lipid metabolic genes were evaluated. Results: NPGM increased subcutaneous and abdominal fat in both sexes and was associated with suppressed gonadal maturation, as indicated by reduced testicular mass relative to body mass and lower testosterone levels in males, as well as a trend toward reduced ovarian mass and lower 17{beta}-estradiol levels in females. Sex-dependent metabolic phenotypes emerged: males exhibited increased body mass gain, hyperphagia, elevated water intake, enlarged liver, pancreas, and heart, higher serum and hepatic triglyceride levels, increased hepatic SCD1 expression, and reduced hepatic CGI-58, PPAR{gamma}, SLC2A2, and CD36. In contrast, females showed fat accumulation without hyperphagia or hepatic triglyceride elevation, accompanied by reduced hepatic VTG2 and APOV1 and decreased adipose ATGL, LPL, and FATP. Hypothalamic AGRP expression decreased in males, whereas both NPY and AGRP decreased in females. Discussion: These findings demonstrate that central NPGM shifts energy allocation from reproduction toward lipid storage through sex-dependent endocrine and metabolic mechanisms, identifying NPGM as a neuroendocrine regulator of energy allocation during sexual maturation in Japanese quails.

Cardiac tissue is primarily made up of cardiomyocytes, which are regulated by the autonomic nervous system. We have used and developed approaches such as patch clamping and electrical stimulation-combined calcium imaging, computer modeling, optogenetics and chemogenetics combining with video-based Short-Time Fourier transformation (STFT) method to study the physiological activities of cardiomyocytes. The action potential of cardiomyocytes was found to be synchronized with calcium signals, which can be grouped into two categories by STFT. A mathematical model was developed to simulate the changes in electrical activities within cardiomyocytes caused by energy depletion, especially for 2-deoxy-D-glucose (2DG) treatment. Optogenetic and chemogenetics tools, such as ChR2(H134R), OptoXR-{beta}2AR and hM3Dq accelerated beating, while GR, ACR1 and hM4Di inhibited cardiomyocytes beating. A video-based STFT method was developed to visualize the beating frequency during these manipulations. An in vitro co-culture method was developed to study the relationship between sympathetic neuronal firing and calcium dynamics in cardiomyocytes. In vivo, electrocardiograph (ECG) measurements showed that Clozapine N-oxide (CNO) caused heart rates increasement in cTnT-hM3Dq virus injected mouse. However, it had no impact on cTnT-hM4Di virus injected mouse. This study provides comprehensive methodologies for studying cardiomyocyte physiology and manipulating heart rates in vitro and in vivo.

CD8 T cells play a central role in immune responses to infection and cancer. However, the diversity of T cell receptor (TCR) specificities makes it challenging to study the mechanisms that regulate T cell activation, differentiation, and effector function. Beyond TCR transgenic mouse models, various complex genome-editing approaches have been employed to overcome this challenge. However, these strategies are often technically demanding, time-intensive, and difficult to adapt. Investigators who are interested in testing de novo TCRs under their chosen experimental conditions would benefit from a standardized and accessible method. Here, we describe a protocol that combines ribonucleoprotein (RNP)-based CRISPR-Cas9 editing with retroviral transduction to enable efficient genetic manipulation of murine CD8 T cells. We show that T cells engineered via this protocol can be generated at sufficient scale for downstream in vitro assays and in vivo adoptive transfer experiments. We expect this method will be useful for investigators who require a standardized and accessible way to study how TCR specificity impacts CD8 T cell responses.

BACH1 is a heme-regulated basic-leucine-zipper containing transcriptional repressor that binds its DNA recognition elements as a heterodimer with MAFK. Heme-binding is thought to be mediated by several Cys-Proline (CP) motifs and this results in dissociation of the heterodimer from DNA. The mechanism of heme-binding and heme-mediated DNA dissociation remains unresolved. We have used UV-visible spectroscopy, 2D-NMR and DNA-binding assays to explore both heme-binding and DNA dissociation of a minimal BACH1 construct containing 2 CP motifs (C492(CP5) and C646(CP6)) flanking the DNA-binding domain. We find that heme is able to bind to both CP motifs, but also to other non-CP cysteines and histidines in the construct. Using NMR spectroscopy, we identify a structured binding pocket in which heme interacts with both C646(CP6) and Cys621. However, DNA-binding assays show that C646(CP6) is not required for heme-mediated DNA dissociation of the BACH1:MAFK heterodimer. Using UV-visible spectroscopy we show that C492(CP5) also recruits heme with a second ligand, a conserved histidine, His559, in the BACH1 DNA-recognition helix. Mutation of C492(CP5) reduces but does not abolish heme-mediated dissociation from DNA. Our findings suggest a mechanism for heme-binding to BACH1 and heme-mediated dissociation from DNA.

Adipose-derived mesenchymal stem cells (gAD-MSCs) are promising candidates for veterinary regenerative medicine, yet the characterization of gAD-MSCs from locally adapted Indonesian goat breeds remains limited. This study aimed to isolate and characterize gAD-MSCs from Peranakan Ettawa (PE) goats using tissue explant culture. Subcutaneous adipose tissue was collected from the base of the tail of healthy PE goats (n=3). Primary cell outgrowth from explants was observed by Day 5, displaying characteristic fibroblast-like, spindle-shaped morphology and strong plastic adherence. Serial passaging to Passage 3 (P3) yielded a morphologically stable, homogeneous cell population. Assessment of cellular metabolic activity via the resazurin assay demonstrated sustained cell viability and a statistically significant increase in metabolic activity between Day 3 and Day 5 (p < 0.05). Furthermore, functional clonogenic capacity, evaluated using the colony-forming unit (CFU) assay, showed continuous temporal expansion of colonies over 14 days, yielding an average of 52.0 + - 4.1 colonies per dish. These findings confirm that expanded gAD-MSCs P3from PE goats maintain characteristic mesenchymal morphology, sustained metabolic activity, and clonogenic capacity. This work provides a baseline cellular profile of PE goat gAD-MSCs, supporting their potential use in veterinary regenerative medicine and tissue engineering.

Prolonged low-temperature exposure may extend the preservation window of mammalian cells but can also disrupt cellular homeostasis and ultimately compromise cell viability. This study investigated the time-dependent phenotypic and transcriptomic responses of primary canine dermal fibroblasts to sustained hypothermic stress. Passage-three fibroblasts were continuously maintained at 15 for up to 15 days, with samples collected on Days 0, 3, 6, 9, 12, and 15. Cellular morphology, metabolic activity and viability, and apoptosis were evaluated using bright-field microscopy, Cell Counting Kit-8 assays, and Annexin V-FITC/propidium iodide flow cytometry, respectively. RNA sequencing was performed to characterize dynamic transcriptional changes throughout the exposure period. Early low-temperature exposure was associated with relatively preserved cellular morphology and viability, suggesting a transient adaptive response. With increasing exposure duration, fibroblasts exhibited progressive morphological deterioration, reduced metabolic activity, loss of adhesion, and increased apoptosis. Time-series transcriptomic analysis further revealed temporally coordinated and stage-dependent gene-expression programs associated with metabolic regulation, cellular stress responses, structural homeostasis, and cell survival. Integration of phenotypic and transcriptomic data demonstrated that the response of primary canine dermal fibroblasts to 15 was dynamic rather than linear, progressing from early adaptation to cumulative dysfunction during prolonged exposure. These findings provide a framework for defining the low-temperature tolerance of primary canine dermal fibroblasts and may inform the optimization of protocols for their short- to medium-term preservation and transportation.

Monogenean capsalids of the genus Neobenedenia are widespread parasites of wild and farmed marine fish, and represent a great threat to the mariculture of grouper in China. Fishery drug development to screen and find effective compounds to control and prevent the disease is urgent needed, considering the vast production of grouper in China (294 ktons in 2025). Annexins have been discovered in Neobenedenia and other parasites, and marked differences between the parasite annexins and those of the hosts make them potentially attractive drug targets for anti-parasite therapeutics. Herein, we utilized computer-based drug discovery screens using unique Neobenedenia melleni annexin B1 and a database of 1,456,161 small molecules. The 3D structure of annexin B1 was firstly modeled by three different protein prediction tools, namely AlphaFold 3, SWISS-MODEL, and I-TASSER, of which the most accurate protein structure was used as the drug target for the following structure-based virtual screening. In vivo experimental validation of 11 compounds after molecular docking shows that abamectin (Aba) has the most effective anti-Neobenedenia bioactivity at the concentration of 0.16 mg/L as the initial screening concentration. Given its low toxicity to host grouper (24 LC50=0.254 mg/L), abamectin was chose for further investigation. A 24 h bath exposure successfully lowered the parasitic load in infected grouper, yielding an 24 h EC50 of 0.033 mg. To elucidate the anti-parasite mechanism, long-timescale molecular dynamics simulations (1000 ns) of annexin B1 and Aba was conducted, which allowed for atomic and molecular-level analysis of the essential protein motions involved in the interaction of annexin B1 and its substrate. The interaction profile between annexin B1 and abamectin was dominated by hydrophobic contacts and water bridges, involving residues TYR-210, GLU-214, GLU-244, and SER-247, which path a way for further drug optimization.