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Identification of novel cytoskeleton protein involved in spermatogenic cells and sertoli cells of non-obstructive azoospermia based on microarray and bioinformatics analysis.

BACKGROUND: During mammalian spermatogenesis, the cytoskeleton system plays a significant role in morphological changes. Male infertility such as non-obstructive azoospermia (NOA) might be explained by studies of the cytoskeletal system during spermatogenesis. METHODS: The cytoskeleton, scaffold, and actin-binding genes were analyzed by microarray and bioinformatics (771 spermatogenic cellsgenes and 774 Sertoli cell genes). To validate these findings, we cross-referenced our results with data from a single-cell genomics database. RESULTS: In the microarray analyses of three human cases with different NOA spermatogenic cells, the expression of TBL3, MAGEA8, KRTAP3-2, KRT35, VCAN, MYO19, FBLN2, SH3RF1, ACTR3B, STRC, THBS4, and CTNND2 were upregulated, while expression of NTN1, ITGA1, GJB1, CAPZA1, SEPTIN8, and GOLGA6L6 were downregulated. There was an increase in KIRREL3, TTLL9, GJA1, ASB1, and RGPD5 expression in the Sertoli cells of three human cases with NOA, whereas expression of DES, EPB41L2, KCTD13, KLHL8, TRIOBP, ECM2, DVL3, ARMC10, KIF23, SNX4, KLHL12, PACSIN2, ANLN, WDR90, STMN1, CYTSA, and LTBP3 were downregulated. A combined analysis of Gene Ontology (GO) and STRING, were used to predict proteins' molecular interactions and then to recognize master pathways. Functional enrichment analysis showed that the biological process (BP) mitotic cytokinesis, cytoskeleton-dependent cytokinesis, and positive regulation of cell-substrate adhesion were significantly associated with differentially expressed genes (DEGs) in spermatogenic cells. Moleculare function (MF) of DEGs that were up/down regulated, it was found that tubulin bindings, gap junction channels, and tripeptide transmembrane transport were more significant in our analysis. An analysis of GO enrichment findings of Sertoli cells showed BP and MF to be common DEGs. Cell-cell junction assembly, cell-matrix adhesion, and regulation of SNARE complex assembly were significantly correlated with common DEGs for BP. In the study of MF, U3 snoRNA binding, and cadherin binding were significantly associated with common DEGs. CONCLUSION: Our analysis, leveraging single-cell data, substantiated our findings, demonstrating significant alterations in gene expression patterns.

Male

Bioinformatic analysis reveals the potential association of ESRP1 with the splicing of cytoskeleton-associated genes in doxorubicin-resistant MCF7 breast cancer cells.

BACKGROUND: Breast cancer remains one of the most prevalent malignancies among women, with doxorubicin resistance posing a significant challenge that undermines treatment success and survival outcomes. Aberrant alternative splicing (AS), driven by dysregulation or mutations in splicing factors (SFs), is implicated in cancer initiation, progression, and drug resistance. This study aims to investigate the association of the epithelial cell-specific splicing factor ESRP1 with doxorubicin resistance in breast cancer, focusing on how ESRP1 deficiency correlates with AS changes that promote chemoresistance. METHODS: We analyzed RNA-sequencing (RNA-seq) data from doxorubicin-resistant (MCF7-DR) and parental (MCF7) breast cancer cell lines to identify enhanced alternative splicing events (ASEs) and changes in ESRP1 expression; we further leveraged The Cancer Genome Atlas (TCGA)-BRCA cohort to construct an SF-RASE correlation network for screening core SFs (including ESRP1). An integrative analysis combining crosslinking immunoprecipitation (CLIP-seq) data and The Cancer Genome Atlas (TCGA) database was performed to validate ESRP1 binding targets and assess the association between ESRP1-related splicing and cytoskeleton organization. RESULTS: We observed extensive AS changes and significantly downregulated ESRP1 expression in MCF7-DR cells. Integrative analysis identified 61 high-confidence ASEs that correlate with ESRP1 expression. Further bioinformatic integration suggests that ESRP1 expression is associated with the splicing patterns of SPTBN1, MAP2K7, FGFR3, and CYB561A3-four genes involved in cytoskeleton organization-though direct experimental verification to confirm a causal regulatory relationship between ESRP1 and the splicing of these genes is still pending. CONCLUSIONS: Our findings suggest that ESRP1 expression is closely associated with doxorubicin resistance in breast cancer cells, with concomitant alterations in key ASEs linked to cytoskeletal remodeling that correlate with ESRP1. Exploring the ESRP1-related splicing network may offer new strategies to overcome chemoresistance and improve patient outcomes. However, the small cell line sample size (n = 2 per group) constrains the robustness of ASE and SF-ASE correlation findings, and these results should be interpreted with caution and require further validation with larger sample cohorts.

Alternative splicing

Tear fluid reflects the altered protein expressions of Alzheimer's disease patients in proteins involved in protein repair and clearance system or the regulation of cytoskeleton.

BackgroundNew biomarkers that improve diagnosis of Alzheimer's disease (AD) are warranted. Tear fluid (TF) containing variety of proteins that reflect pathophysiological changes of systemic diseases makes TF proteins potential biomarker candidates for AD.ObjectiveWe investigated the expression levels of TF proteins in persons with mild AD and cognitively healthy controls (CO) to find out if altered proteins may link to the AD pathophysiology.MethodsWe analyzed the data of the 53 study participants (34 COs, mean age 71 and Mini-Mental State Examination (MMSE) 28.9 ± 1.4 and 19 persons with AD, CDR 0.5-1, mean age 71 and MMSE 23.8 ± 2.8). All went through neurological status examination, cognitive tests, and ophthalmological examination. TF was collected using Schirmer strips. The TF protein content was evaluated via mass spectrometry-based proteomics and label-free quantification.ResultsEleven proteins having a role either in protein repair and clearance system, or regulation of cytoskeleton, showed altered expression in AD group compared to CO group. Seven of them were significantly (p ≤ 0.05) upregulated (Sti1, Twf1, Myl6, Otub1, Pls1 and Caza1) or, downregulated (HSP90) in AD group.ConclusionsAltered expression of all these up- or downregulated proteins may be linked to AD pathophysiology. Thus, our results are encouraging for searching new biomarker candidates for AD. TF is potential biomarker candidate, because TF seems to reflect altered protein levels already in mild AD dementia.

Humans

Remodeling of cytoskeleton, chromatin, and gene expression during mechanical rejuvenation of aged human dermal fibroblasts.

Aging is associated with a progressive decline in cellular function. To reset the aged cellular phenotype, various reprogramming approaches, including mechanical routes, have been explored. However, the epigenetic mechanisms underlying cellular rejuvenation are poorly understood. Here, we studied the cytoskeletal, genome-wide chromatin and transcriptional changes in young, aged, and mechanically rejuvenated fibroblasts using immunofluorescence, RNA sequencing, and Hi-C experiments. The mechanically rejuvenated aged fibroblasts, that had partially reset their transcription to a younger cell state, showed a local reorganization of the interchromosomal contacts and lamina-associated domains. Interestingly, the observed chromatin reorganization correlated with the transcriptional changes. Immunofluorescence experiments in the rejuvenated state confirmed increased actomyosin contractility like younger fibroblasts. In addition, the rejuvenated contractile properties were maintained over multiple cell passages. Overall, our results give an overview of how changes in the cytoskeleton, chromatin, and gene activity are connected to aging and rejuvenation.

Humans

Nap1-mediated actin remodeling is essential for mammalian myoblast fusion.

Myoblast fusion is crucial for the formation, growth, maintenance and regeneration of healthy skeletal muscle. Unfortunately, the molecular machinery, cell behaviors, and membrane and cytoskeletal remodeling events that govern fusion and myofiber formation remain poorly understood. Using time-lapse imaging approaches on mouse C2C12 myoblasts, we identify discrete and specific molecular events at myoblast membranes during fusion and myotube formation. These events include rearrangement of cell shape from fibroblast to spindle-like morphologies, changes in lamellipodial and filopodial extensions during different periods of differentiation, and changes in membrane alignment and organization during fusion. We find that actin-cytoskeleton remodeling is crucial for these events: pharmacological inhibition of F-actin polymerization leads to decreased lamellipodial and filopodial extensions and to reduced myoblast fusion. Additionally, shRNA-mediated inhibition of Nap1, a member of the WAVE actin-remodeling complex, results in accumulations of F-actin structures at the plasma membrane that are concomitant with a decrease in myoblast fusion. Our data highlight distinct and essential roles for actin cytoskeleton remodeling during mammalian myoblast fusion, provide a platform for cellular and molecular dissection of the fusion process, and suggest a functional conservation of Nap1-regulated actin-cytoskeleton remodeling during myoblast fusion between mammals and Drosophila.

Actins

Cytoskeletal mechanisms regulating attaching/effacing bacteria interactions with host cells: It takes a village to build the pedestal.

The actin cytoskeleton is a key cellular structure subverted by pathogens to infect and survive in or on host cells. Several pathogenic strains of Escherichia coli, such as enteropathogenic E. coli (EPEC) and enterohemorrhagic E. coli (EHEC), developed a unique mechanism to remodel the actin cytoskeleton that involves the assembly of actin filament-rich pedestals beneath the bacterial attachment sites. Actin pedestal assembly is driven by bacterial effectors injected into the host cells, and this structure is important for EPEC and EHEC colonization. While the interplay between bacterial effectors and the actin polymerization machinery of host cells is well-understood, how other mechanisms of actin filament remodelling regulate pedestal assembly and bacterial attachment are poorly investigated. This review discusses the gaps in our understanding of the complexity of the actin cytoskeletal remodelling during EPEC and EHEC infection. We describe possible roles of actin depolymerizing, crosslinking and motor proteins in pedestal dynamics, and bacterial interactions with the host cells. We also discuss the biological significance of pedestal assembly for bacterial infection.

Humans

AFL1 is a phosphoinositide phosphate- and actin-binding protein.

At14a-Like 1 (AFL1) is highly induced during low water potential stress and remains at high levels during stress acclimation. AFL1, and the closely related At14a, are plant-specific proteins that have limited similarity to mammalian actin- and membrane-associated proteins. Previous research indicated that manipulation of AFL1 expression affects actin cytoskeleton dynamics and endocytic trafficking (as measured by uptake of membrane dye FM4-64). However, it has remained unclear whether this is a direct activity of AFL1 or an indirect effect. We found that AFL1 specifically bound actin filaments as well as the phosphoinositide phosphates (PIPs) phosphoinositide-3-monophosphate [PI(3)P], PI(5)P, and the diphosphate PI(3,5)P2 in co-sedimentation and PIP strip membrane assays, respectively. Interestingly, these binding activities were mediated by the same site within the C-terminal domain of AFL1. Mutation of a single amino acid in the AFL1 C-terminal domain was sufficient to disrupt both actin filament and PIP binding in vitro and to disrupt accumulation of the mutated protein in transgenic plants. We also found that the central hydrophobic region of AFL1 was required for AFL1 co-localization with actin filaments and plasma membrane. Mutation of AFL1 and At14a using genome editing confirmed that loss of these proteins reduced growth during low water potential stress and resulted in less extensive actin filament arrays and disrupted FM4-64 uptake. Together these observations indicate that AFL1 can directly participate in cytoskeleton organization and membrane dynamics via PIP and actin filament binding.

Arabidopsis

Microfluidics to Follow Spatiotemporal Dynamics at the Nucleo-Cytoplasmic Interface During Plant Root Growth.

Nuclear dynamics refers to global/local changes in the molecular and spatial organization of genomic DNA that can occur during development or in response to environmental stress signals and eventually impact genomic functions. In plants, nuclear dynamics relies notably on the connection of the nucleus with the cytoskeleton during development. It orchestrates genomic functions in response to developmental and environmental cues. This is particularly true in the plant root system, which is constantly exposed to a wide range of internal and external stimuli. Currently, studying nuclear dynamics in a growing root is challenging due to limitations regarding real-time imaging for quantitative analyses under controlled conditions. Microfluidic systems for plant cell studies are valuable analytical tools that provide precise control of culture conditions together with live-imaging capabilities at high temporal and spatial resolutions. Herein, we describe a microfluidic platform to unravel dynamically and noninvasively nuclear organization in the seedling root system exposed to various treatments. As exemplified here, our microfluidic platform can be conveniently used for real-time microscopy imaging and quantitative analysis of fine nuclear morphological changes upon modifying cytoskeleton dynamics. Importantly, our system can be applied to a wide variety of microscopic means including high-resolution microscopy to investigate diverse subcellular compartments or nuclear domains in Arabidopsis thaliana roots.

Plant Roots

Astrocyte reactivity by alcohol dependence in the central amygdala.

Astrocytes play essential roles in maintaining brain homeostasis and in contributing to synaptic functions, but, in response to injury, infection, or disease, astrocytes can downregulate their homeostatic and physiological functions while increasing neuroinflammatory responses. The central amygdala (CeA) is important for stress responsivity and the development of alcohol (ethanol) dependence. Using a multi-omics approach in Aldh1l1-EGFP/Rpl10a mice and the chronic intermittent ethanol two-bottle choice (CIE-2BC) model, we have characterized the translational response of CeA astrocytes, as well as the proteomic and phosphoproteomic changes in ethanol dependent, non-dependent, and naïve mice. We identified astrocyte-specific alterations in neuroimmune functions and antioxidant/oxidative stress pathways in ethanol dependent mice as well as cytoskeletal plasticity related pathways in non-dependent mice. Proteomic analysis showed down-regulation of astrocyte physiological functions in dependent animals while phosphoproteomic analysis identified pathways associated with cytoskeleton remodeling in both dependent and non-dependent mice. Reconstructions of astrocyte morphologies demonstrated increased CeA astrocyte complexity in dependent and non-dependent groups compared to naïve mice. The astrocyte-specific activation of neuroimmune and antioxidant pathways, down-regulation of homeostatic functions, alteration in protein phosphorylation-mediated cytoskeleton remodeling, and increased astrocyte morphological complexity demonstrate that ethanol dependence induces astrocyte reactivity in the CeA consistent with both adaptive and maladaptive changes. These findings highlight the role of CeA astrocytes in the progression from alcohol intake to dependence and represent a first step toward identifying astrocyte-specific therapeutic strategies to treat Alcohol Use Disorder (AUD) aimed at potentiating reactive astrocyte adaptive changes and inhibiting maladaptive responses.

Animals

Comparative proteomic analysis reveals the pathological mechanisms of overuse achilles tendinopathy and the therapeutic mechanisms of ESWT and PRP.

BACKGROUND: Achilles tendinopathy is a common musculoskeletal disorder with limited self-repair capacity. Although extracorporeal shock wave therapy (ESWT) and platelet-rich plasma (PRP) are widely used, their therapeutic mechanisms remain unclear. METHODS: A rat model of overuse Achilles tendinopathy was established by uphill treadmill running. Tendon morphology and structure were assessed by ultrasound and histology, and proteomic profiling was performed to identify differentially expressed proteins (DEPs) and enriched pathways. RESULTS: Ultrasound revealed subcutaneous edematous infiltration after overuse, and histology showed disorganized collagen fibers and altered cellular density. Compared with the normal group, the injury group showed 429 DEPs, which were enriched in pathways related to actin cytoskeleton and complement and coagulation cascades. Both ESWT and PRP treatments ameliorated these overuse-induced pathological changes. Compared with the rest group, the ESWT group showed 30 DEPs, while the PRP group showed 244, with 17 DEPs overlapping between the two comparisons. In the ESWT group, enriched pathways included actin cytoskeleton organization, protein stabilization, and sulfur metabolism. In the PRP group, enriched pathways included FcγR-mediated phagocytosis, lysosome, and endoplasmic reticulum protein processing. Compared with the normal group, the ESWT group showed 32 DEPs, whereas the PRP group showed only one (Serpina6), which was the only protein shared between the two comparisons. CONCLUSION: ESWT and PRP improve tendon healing in overuse Achilles tendinopathy through different molecular mechanisms. The PRP group showed a proteomic profile more similar to the normal group than the ESWT group. These findings provide a molecular basis for optimizing clinical treatment strategies.

Animals

A complex of MAST1 and 14-3-3η regulates Tau phosphorylation in the developing cortex.

The MAST family of serine/threonine kinases has been implicated in a spectrum of human neurodevelopmental disorders. However, little is known about their biological function or regulation. Seeking to fill these gaps in our knowledge, we have identified upstream and downstream partners of MAST1. 14-3-3η, a neuronal 14-3-3 paralog, specifically interacts with MAST1 at two regulatory serines, S90 and S161. p21-activated kinase (PAK), a neuronal regulator of the actin cytoskeleton, phosphorylates MAST1 to regulate its interaction with 14-3-3η. Exploiting mouse models of human Mega-Corpus-Callosum Syndrome (MCC) and whole brain phosphoproteomics, we identify the microtubule-associated protein Tau as a candidate substrate of MAST1. We show that pathogenic MAST1 mutations perturb protein function either through misfolding or attenuation of kinase activity. Our data are consistent with a model in which the MAST kinases couple PAK, a neuronal regulator of the actin cytoskeleton, to microtubule remodeling during the differentiation and specification of cortical neurons.

Animals

Mechanotransduction in musculoskeletal mesenchymal tissues: implications for bone, tendon, and cartilage regenerative engineering-a narrative review.

PURPOSE/AIM OF THE STUDY: To integrate evidence on how mechanical signals regulate musculoskeletal connective-tissue biology and how cellular context and loading history shape mechanotransduction and mechanical memory. MATERIALS AND METHODS: This narrative review synthesized PubMed-indexed evidence on extracellular matrix mechanics, adhesion complexes, the cytoskeleton, nucleus, primary cilia, mechanosensitive ion channels, cell state, and loading history in bone, tendon, ligament, and cartilage. RESULTS: Mechanotransduction is best understood as a coupled extracellular matrix-integrin-cytoskeleton-nucleus continuum rather than as independent cytoskeletal or nuclear drivers. Responses are conditioned by lineage stage, anatomic niche, inflammation, cellular subpopulation, and prior mechanical exposure. Mechanical memory may be encoded through persistent YAP/TAZ activity, microRNA programs, DNA methylation, histone modifications, chromatin architecture, and metabolic remodeling. Evidence is strongest for bone, including Piezo-dependent osteogenesis, TRPV4-mediated shear sensing, viscoelastic compression, osteocyte-stromal extracellular-vesicle signaling, and osteogenesis-angiogenesis coupling. Tendon and ligament require anisotropic architecture and strain-window control, whereas cartilage shows a narrow distinction between physiologic TRPV4-associated anabolism and high-strain or inflammation-sensitized Piezo/YAP-mediated maladaptation. CONCLUSIONS: Translational implications include mechanically defined cell expansion, biomaterial preconditioning, stage-specific rehabilitation, and potency assays incorporating loading history. Direct clinical validation of stable perioperative cellular mechanical memory remains limited. Future studies should combine controlled mechanical perturbation with bulk and single-cell RNA sequencing, chromatin-accessibility profiling, spatial methods, and perturbational genomics.

Mechanotransduction

Phosphoproteomic Profiling of Early-Stage Non-Small Cell Lung Cancer Provides Preliminary Evidence of Phosphorylation-Regulated Rho GTPase Signaling Driving Cytoskeletal Remodeling, Angiogenesis, and Cell Cycle Progression.

Non-small cell lung cancer (NSCLC) is the primary cause of cancer-related deaths worldwide. This can be attributed to the difficulty in early detection and the limited efficacy of available treatments, partly due to an incomplete understanding of the disease biology. Identification of key proteins involved in early-stage progression and understanding the underlying mechanisms can greatly contribute to the development of diagnostic and treatment strategies for NSCLC. Quantitative phosphoproteomic analysis was done on paired tumor tissues and adjacent normal lung tissues from early-stage NSCLC adenocarcinoma (LUAD) patients to allow for the identification of proteins with differential phosphorylation and their associated pathways. A total of 6483 phosphoproteins were identified, with 1229 proteins having significantly higher phosphorylation and 701 proteins having significantly lower phosphorylation in the tumor tissues. All MS data were deposited in ProteomeXchange with the identifier PXD071583. Function enrichment analysis showed that the differentially phosphorylated proteins and phosphosites were primarily involved in Rho GTPase signaling and cytoskeleton remodeling. Analysis of protein interaction networks suggests that the predicted kinase activity likely drives malignant transformation in NSCLC LUAD, presumably through Rho GTPase-mediated angiogenesis and cell cycle progression. More importantly, this study identified several protein phosphosites with differential phosphorylation and inferred kinase-phosphosite activities that have not previously been reported in NSCLC LUAD.

Humans

Role of semaphorin 4f in cardiac fibroblasts to regulate matrix production through actin remodeling and YAP/TAZ activation.

Cardiac fibrosis remains a critical determinant of adverse outcomes in heart disease, yet effective anti-fibrotic therapies are lacking. While multiple semaphorin family members participate in cardiovascular pathophysiology, the role of semaphorin 4f (Sema4f) in cardiac fibrosis remains unexplored. This study investigates the role and mechanisms of Sema4f in fibrotic remodeling post-myocardial infarction (MI). We employed flow cytometry to characterize cell type-specific Sema4f expression patterns in post-MI hearts. Lineage-specific knockout mice (fibroblast vs. myeloid) were subjected to left anterior descending ligation to assess functional consequences. Proteomic analysis of Sema4f-deficient cardiac fibroblasts was conducted to identify downstream effectors. Key pathways were subsequently validated using pharmacological inhibitors. We found that Sema4f expression was markedly upregulated during the fibrotic phase post-MI, primarily due to fibroblast activation. Fibroblast-, but not myeloid-, specific Sema4f deletion significantly reduced fibrosis and improved cardiac function. Proteomic profiling revealed that Sema4f deficiency led to downregulation of pro-fibrotic gene expression, which was associated with impaired actin cytoskeletal remodeling and decreased nuclear translocation of YAP/TAZ. Pharmacological inhibition of either actin remodeling or YAP/TAZ activity attenuated fibrosis, whereas YAP/TAZ activation abolished the anti-fibrotic effects of Sema4f knockout. Our study provides the first evidence demonstrating the functional role of Sema4f in cardiac fibroblast activation and fibrosis progression. We have identified a fibroblast-specific mechanism mediated by the Sema4f-actin cytoskeleton-YAP/TAZ axis, offering novel mechanistic insights into fibrosis regulation and revealing a promising therapeutic target for cardiac fibrosis with potential clinical applications.

Animals

The Myo2 adaptor Ldm1 and its receptor Ldo16 mediate actin-dependent lipid droplet motility.

Organelle motility enables strategic cellular reorganizations. In yeast, this process depends on the actin cytoskeleton, type V myosin motor proteins, and organelle-specific myosin adaptor proteins. While the myosin adaptors for most organelles are known, the coupling of myosin to lipid droplets (LDs), the cellular lipid storage organelles, remained enigmatic. Using genome-wide screening, we identified Ldm1 (lipid droplet motility 1/Yer085c) as a myosin adaptor. Ldm1 binds to the globular tail domain of the myosin Myo2 and to the LD surface protein Ldo16 to enable actin-dependent LD motility. Ldo16 has additional roles in LD contact sites to the vacuole and the endoplasmic reticulum, suggesting a coordination of LD motility and organelle tethering. Ldm1 has a second role in mitochondrial transport, and elevated Ldm1 levels rescue defects of the mitochondrial Myo2-adaptors Mmr1/Ypt11. Our work identifies the molecular machinery for LD motility and contributes to a comprehensive understanding of acto-myosin-based cellular reorganization.

Lipid Droplets

Genome-wide CRISPR interference screen identifies Clip2 as a novel regulator of osteocyte maturation and morphology.

Osteocytes play critical roles in bone, making them attractive targets for therapeutics aimed at improving bone mass and strength. The genes driving osteocyte maturation and function are not fully understood. Here, we aimed to identify novel genes responsible for osteocyte differentiation and dendrite development by performing a genome-wide CRISPR-interference (CRISPRi) screen in the Ocy454 osteocyte-like cell line. We identify CD61 (integrin β3) as a marker of osteocyte maturation: surface CD61 expression increases during osteocyte maturation, and CD61high cells express higher levels of osteocyte marker genes. We then developed a flow cytometry-based assay to quantify surface CD61 protein levels as a phenotypic endpoint for functional genomic screening. In a genome-wide screen, we identified Clip2, which encodes a microtubule-binding protein, as one of dozens of genes necessary for CD61 expression. Clip2 inhibition decreased surface CD61 expression, reduced expression of osteocyte-specific genes Dmp1 and Sost, and impaired dendrite morphology in vitro. Together, these results highlight the utility of surface CD61 as a marker of osteocyte maturity and identify the role of the microtubule cytoskeleton for osteocyte differentiation, form, and function.

Osteocytes

Function and interactions of a protein bridge between the inner membrane complex and subpellicular microtubules in Toxoplasma gondii.

Toxoplasma gondii is an intracellular parasite that utilizes peripheral membrane and cytoskeletal structures for essential functions such as host cell invasion and replication. These include the inner membrane complex (IMC) and the underlying longitudinal subpellicular microtubules (SPMT) that provide support for the IMC and give the parasite its distinctive crescent shape. Although the IMC and SPMTs have been studied separately, the mechanisms linking these adjacent structures remain largely unknown. This study identifies a protein named IMT1 that localizes to the maternal IMC and SPMTs and appears to tether the IMC to the microtubules. We disrupt the IMT1 gene to assess function and then use deletion analyses and mutagenesis to reveal regions of the protein that are necessary for binding to the IMC cytoskeleton or SPMTs. Using proximity labeling, we identify candidate IMT1 interactors in the IMC or SPMTs. Exploration of these candidates reveals that the loss of IMT1 results in a dramatic reduction of the microtubule-associated protein TLAP2 and that IMT1 binds directly to the cytoskeletal IMC proteins IMC1, IMC18, and IMC24. Together, these interactions reveal a novel bridge that connects two key cytoskeletal structures and provides new insight into the organization of the structural backbone of T. gondii.

Toxoplasma

Multi-Omics Platforms Reveal Synergistic Intestinal Toxicity in Tilapia from Acute Co-Exposure to Polystyrene Microplastics, Sulfamethoxazole, and BDE153.

Polystyrene microplastic (MP) and its co-existing contaminants may exert different toxic effects on its surrounding aquatic organisms. In order to detect the intestinal harmful responses, tilapia were subjected to exposure with 75 nm of MPs, 100 ng·L-1 of sulfamethoxazole (SMZ), 5 ng·L-1 of BDE153, and combinations thereof over periods of 2, 4, and 8 days. Enzymatic assays, transcriptomics, proteomics, and metabolomics were employed to evaluate intestinal histopathological effects. Results showed that significant reductions were observed in ATP, ROS, SOD, EROD, lipid metabolism-related enzymes, pro-inflammatory cytokines (TNFα and IL-1β), and apoptosis marker caspase 3 across all groups at day 8. Histological evaluation revealed diminished goblet cell density, with distinct vacuole formation in the BDE153+MPs group. KEGG pathway analysis highlighted disruptions in endocytosis, MAPK signaling, phagosome formation, and actin cytoskeleton regulation. Proteomic findings indicated notable enrichment in endocytosis (decreased sorting nexin-2; increased Si:dkey-13a21.4), MAPK/PPAR signaling, protein processing in the endoplasmic reticulum (Sec61 subunit gamma), and cytoskeletal modulation (reduced fibronectin; elevated activation peptide fragment 1), with or without SMZ and BDE153. Metabolomic profiling showed significant alterations in ABC transporters, aminoacyl-tRNA biosynthesis, protein digestion and absorption, and linoleic acid metabolism. In summary, these findings suggest that BDE153 and MPs synergistically exacerbate intestinal damage and gene/protein expression over time, while SMZ appears to exert an antagonistic, mitigating effect.

Animals