The integrins

Therapeutic potential of exercise-hormone irisin in Alzheimer's disease

Irisin is a myokine that is generated by cleavage of the membrane protein fibronectin type III domain-containing protein 5 (FNDC5) in response to physical exercise. Studies reveal that irisin/FNDC5 has neuroprotective functions against Alzheimer's disease, the most common form of dementia in the elderly, by improving cognitive function and reducing amyloid-β and tau pathologies as well as neuroinflammation in cell culture or animal models of Alzheimer's disease. Although current and ongoing studies on irisin/FNDC5 show promising results, further mechanistic studies are required to clarify its potential as a meaningful therapeutic target for alleviating Alzheimer's disease. We recently found that irisin treatment reduces amyloid-β pathology by increasing the activity/levels of amyloid-β-degrading enzyme neprilysin secreted from astrocytes. Herein, we present an overview of irisin/FNDC5's protective roles and mechanisms against Alzheimer's disease.

Leveraging the predictive power of a 3D in vitro vascularization screening assay for hydrogel-based tissue-engineered periosteum allograft healing

A common strategy for promoting bone allograft healing is the design of tissue-engineered periosteum (TEP) to orchestrate host-tissue infiltration. However, evaluating requires costly and time-consuming in vivo studies. Therefore, in vitro assays are necessary to expedite TEP designs. Since angiogenesis is a critical process orchestrated by the periosteum, this study investigates in vitro 3D cell spheroid vascularization as a predictive tool for TEP-mediated in vivo healing. Spheroids of human umbilical vein endothelial cells (HUVECs) and human mesenchymal stem cells (hMSCs) are encapsulated in enzymatically-degradable poly (ethylene glycol)-based hydrogels and sprout formation, network formation, and angiogenic growth factor secretion are quantified. Hydrogels are also evaluated as TEP-modified allografts for in vivo bone healing with graft vascularization, callus formation, and biomechanical strength quantified as healing metrics. Evaluation of hydrogels highlights the importance of degradation, with 24-fold greater day 1 sprouts observed in degradable hydrogels in vitro and 4-fold greater graft-localized vascular volume at 6-weeks in vivo compared to non-degradable hydrogels. Correlations between in vitro and in vivo studies elucidate linear relationships when comparing in vitro sprout formation and angiocrine production with 3- and 6-week in vivo graft vascularization, 3-week cartilage callus, and 6-week bone callus, with a Pearson's R2 value equal to 0.97 for the linear correlation between in vitro sprout formation and 6-week in vivo vascular volume. Non-linear relationships are found between in vitro measures and bone torque strength at week 6. These correlations suggest that the in vitro sprouting assay has predictive power for in vivo vascularization and bone allograft healing.

Unravelling the role of tumor microenvironment responsive nanobiomaterials in spatiotemporal controlled drug delivery for lung cancer therapy

Design and development of efficient drug delivery technologies that impart site-specificity is the need of the hour for the effective treatment of lung cancer. The emergence of materials science and nanotechnology partially helped drug delivery scientists to achieve this objective. Various stimuli-responsive materials that undergo degradation at the pathological tumor microenvironment (TME) have been developed and explored for drug delivery applications using nanotechnological approaches. Nanoparticles (NPs), owing to their small size and high surface area to volume ratio, demonstrated enhanced cellular internalization, permeation, and retention at the tumor site. Such passive accumulation of stimuli-responsive materials helped to achieve spatiotemporally controlled and targeted drug delivery within the tumors. In this review, we discussed various stimuli-physical (interstitial pressure, temperature, and stiffness), chemical (pH, hypoxia, oxidative stress, and redox state), and biological (receptor expression, efflux transporters, immune cells, and their receptors or ligands)-that are characteristic to the TME. We mentioned an array of biomaterials-based nanoparticulate delivery systems that respond to these stimuli and control drug release at the TME. Further, we discussed nanoparticle-based combinatorial drug delivery strategies. Finally, we presented our perspectives on challenges related to scale-up, clinical translation, and regulatory approvals.

Extracellular vesicle surface engineering with integrins (ITGAL & ITGB2) to specifically target ICAM-1-expressing endothelial cells

Extracellular vesicles (EVs) are taken up by most cells, however specific or preferential cell targeting remains a hurdle. This study aims to develop an EV that targets cells involved in inflammation, specifically those expressing intercellular adhesion molecule-1 (ICAM-1). To target these cells, we overexpress the ICAM-1 binding receptor "lymphocyte function-associated antigen-1" (LFA-1) in HEK293F cells, by sequential transfection of plasmids of the two LFA-1 subunits, ITGAL and ITGB2 (CD11a and CD18). The LFA-1 receptor was strongly overexpressed on the EVs released by the transfected cells. We further loaded these EVs with a therapeutic peptide, targeting myeloid differentiation primary response 88 (Myd88; EVMyd88), through a developed EV open-and-close procedure. Myd88 is a downstream common intracellular messenger for most TLR-receptors. EV expression of LFA-1 increases EV binding to ICAM-1-expressing cells, an effect that was dose-dependently inhibited by a specific neutralizing ICAM-1 antibody. Further, activated human endothelial cells treated with LFA-1 EVMyd88 had increased uptake of these EVs, resulting in dose-dependent inhibition of induced release of IL-8, presumably by targeting Myd88. We conclude that LFA-1-expressing EVMyd88 may be a candidate suitable for delivering therapeutic peptides in inflammatory diseases associated with TLR-activation.

Identification of core biomarkers for tuberculosis progression through bioinformatics analysis and in vitro research

Tuberculosis (TB), caused by Mycobacterium tuberculosis (Mtb), remains a significant global public health issue with high mortality rates and challenges posed by drug-resistant strains, emphasizing the continued need for new therapeutic targets and effective treatment strategies. Transcriptomics is a highly effective tool for the development of novel anti-tuberculosis drugs. However, most studies focus only on changes in gene expression levels at specific time points. This study screened for genes with altered expression patterns from available transcriptomic data and analysed their association with the TB progression. Initially, a total of 1228 genes with altered expression patterns were identified through two-way analysis of variance (ANOVA). We define genes with a P-value less than 0.05 for the combined effect of infection and time on gene expression as those with altered expression patterns. Gene Ontology (GO) enrichment analysis revealed that the biological functions of these genes mainly involve DNA translation, RNA processing, and transcriptional regulation. Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis indicated that these genes are primarily associated with fatty acid degradation, pyruvate metabolism, arginine and proline metabolism, as well as cholesterol metabolism signaling pathways. Subsequent Protein-protein interaction (PPI) analysis and Receiver Operating Characteristic (ROC) curve analysis identified four core genes closely associated with TB progression, namely Rac Family Small GTPase 1 (RAC1), Ring-Box 1 (RBX1), Mitochondrial Ribosomal Protein L33 (MRPL33), and ELAV Like RNA Binding Protein 1 (ELAVL1). Q-PCR experiments confirmed that Mtb infection led to changes in the gene expression patterns of RAC1, RBX1, MRPL33, and ELAVL1 in THP-1 cells. These four genes may serve as core biomarkers for TB progression and can be utilized in the development of more effective anti-tuberculosis drugs and host therapy.

Importance of integrin transmembrane helical interactions for antagonistic versus agonistic ligand behavior: Consequences for medical applications

Integrins are well-characterized receptors involved in cell adhesion and signaling. With six approved drugs, they are recognized as valuable therapeutic targets. Here, we explore potential activation mechanisms that may clarify the agonist versus antagonist behavior of integrin ligands. The reorganization of the transmembrane domain (TMD) in the integrin receptor, forming homooligomers within focal adhesions, could be key to the understanding of the agonistic properties of integrin ligands at substoichiometric concentrations. This has significant implications for medical applications. While we focus on the RGD peptide-recognizing integrin subfamily, we propose that these mechanistic insights may also apply to other integrin subtypes. For application of integrin ligands in medicine it is essential to consider this mechanism and its consequences for affinity and bioavailability.

Factors influencing glycocalyx degradation: a narrative review

The glycocalyx is a layer of villus-like structure covering the luminal surface of vascular endothelial cells. Damage to the glycocalyx has been proven linked to the development of many diseases. However, the factors that promote damage to the glycocalyx are not fully elaborated. This review summarizes factors leading to the reduction of the glycocalyx in detail, including inflammatory factors, ischemia-reperfusion, oxidative stress, lipids, glucose, high sodium, female sex hormones and others. Additionally, the mechanisms underlying its degradation are discussed. To better prevent and treat related diseases induced by glycocalyx degradation, it is a meaningful measure to avoid these factors.

Integrin β1 in breast cancer: mechanisms of progression and therapy

The therapy for breast cancer (BC), to date, still needs improvement. Apart from traditional therapy methods, biological therapy being explored opens up a novel avenue for BC patients. Integrin β1 (ITGβ1), one of the largest subgroups in integrin family, is a key player in cancer evolution and therapy. Recent researches progress in the relationship of ITGβ1 level and BC, finding that ITGβ1 expression evidently concerns BC progression. In this chapter, we outline diverse ITGβ1-based mechanisms regarding to the promoted effect of ITGβ1 on BC cell structure rearrangement and malignant phenotype behaviors, the unfavorable patient prognosis conferred by ITGβ1, BC therapy tolerance induced by ITGβ1, and lastly novel inhibitors targeting ITGβ1 for BC therapy. As an effective biomarker, ITGβ1 undoubtedly emerges one of targeted-therapy opportunities of BC patients in future. It is a necessity focusing on scientific and large-scale clinical trials on the validation of targeted-ITGβ1 drugs for BC patients.

Cultured primary turtle hepatocytes: a cellular model for the study of temperature and anoxia

Turtle hepatocytes are a nonexcitable model for metabolic depression during low-temperature and/or anoxic overwintering conditions. Cytoskeletal structure and mitochondrial distribution are continuously modified in cells, and we hypothesized that metabolic depression would inhibit such processes as cell attachment and spreading and promote withdrawal of cell protrusions and peripheral mitochondria. After developing a methodology for culturing painted turtle hepatocytes, two-dimensional (2-D) area and maintenance of cell attachment after a media change were used as indicators of structural rearrangement and spreading/volume. These were measured after incubating cells at varying temperatures and with or without the inclusion of cyanide (chemical proxy for anoxia). Experiments were performed using cells from 22°C- or 5°C-acclimated turtles. Live-cell imaging was used to monitor the effect of cyanide exposure on the distribution of mitochondria. We also acclimated cultured cells from 22°C-acclimated turtles to 4°C in vitro and scored withdrawal of protrusions. Only cells isolated from 5°C-acclimated turtles and incubated at 4°C had reduced attachment to fibronectin substrate, but cyanide exposure had no effect. These cells also had a 30% smaller 2-D area than those from 22°C-acclimated turtles. There was no change in mitochondrial distribution during cyanide perfusion. Finally, 4°C acclimation in vitro resulted in the withdrawal of protrusions over 14 days. Taken together with the results from cells acclimated to low temperature in vivo, this suggests inhibition of structural rearrangement and protrusion stability by low temperature acclimation, but not cyanide exposure. Our cultured primary hepatocyte system will facilitate further study of the role of structural dynamics in reversible metabolic depression.NEW & NOTEWORTHY We have optimized a methodology for two-dimensional (2-D) culturing of primary western painted turtle hepatocytes and used this model to study the effects of cyanide and temperature on structural rearrangement, and the effect of cyanide on mitochondrial distribution. Our results suggest that low temperature acclimation, either in vivo or in vitro, inhibits cell protrusions and structural rearrangement. Acute cyanide exposure did not inhibit structural rearrangement or alter mitochondrial distribution.

Involvement of PDGFR-integrin interactions in the regulation of anoikis resistance in glioblastoma progression

The interactions between platelet-derived growth factor/PDGF receptor and integrin signaling are crucial for cells to respond to extracellular stimuli. Integrin interactions with PDGFR within the lipid rafts activate downstream cellular signaling pathways that regulate cell proliferation, cell migration, cell differentiation, and cell death processes. The mechanisms underlying PDGFR activation mediated receptor internalization, interactions with other cell-surface receptors, particularly extracellular matrix receptors, integrins, and how these cellular mechanisms switch on anchorage-independent cell survival, leading to anoikis resistance are discussed. The role of regulatory molecules such as noncoding RNAs, that can modulate several molecular and cellular processes, including autophagy, in the acquisition of anoikis resistance is also discussed. Overall, the review provides a new perspective on a complex interplay of regulatory cellular machineries involving autophagy, noncoding RNAs and cellular mechanisms of PDGFR activation, PDGFR-integrin interactions, and involvement of lipids rafts in the acquisition of anoikis resistance that regulates glioblastoma progression along with potential future strategies to develop novel therapeutics for glioblastoma multiforme.

Evaluating sex-specific responses to western diet across the lifespan: impact on cardiac function and transcriptomic signatures in C57BL/6J mice at 530 and 640/750 days of age

BACKGROUND

Long-term consumption of Western Diet (WD) is a well-established risk factor for the development of cardiovascular disease (CVD); however, there is a paucity of studies on the long-term effects of WD on the pathophysiology of CVD and sex-specific responses.

METHODS

Our study aimed to investigate the sex-specific pathophysiological changes in left ventricular (LV) function using transthoracic echocardiography (ECHO) and LV tissue transcriptomics in WD-fed C57BL/6 J mice for 125 days, starting at the age of 300 through 425 days.

RESULTS

In female mice, consumption of the WD diet showed long-term effects on LV structure and possible development of HFpEF-like phenotype with compensatory cardiac structural changes later in life. In male mice, ECHO revealed the development of an HFrEF-like phenotype later in life without detectable structural alterations. The transcriptomic profile revealed a sex-associated dichotomy in LV structure and function. Specifically, at 530-day, WD-fed male mice exhibited differentially expressed genes (DEGs), which were overrepresented in pathways associated with endocrine function, signal transduction, and cardiomyopathies. At 750 days, WD-fed male mice exhibited dysregulation of several genes involved in various lipid, glucagon, and glutathione metabolic pathways. At 530 days, WD-fed female mice exhibited the most distinctive set of DEGs with an abundance of genes related to circadian rhythms. At 640 days, altered DEGs in WD-fed female mice were associated with cardiac energy metabolism and remodeling.

CONCLUSIONS

Our study demonstrated distinct sex-specific and age-associated differences in cardiac structure, function, and transcriptome signature between WD-fed male and female mice.

ITGB3 is reduced in pregnancies with preeclampsia and its influence on biological behavior of trophoblast cells

BACKGROUND

Preeclampsia (PE) is a serious pregnancy complication associated with impaired trophoblast function. Integrin β3 (ITGB3) is a cell adhesion molecule that plays a role in cell movement. The objective of this study was to identify the biological function and expression level of ITGB3 in PE.

METHODS

Cell proliferation, migration, invasion, adhesion, and apoptosis were estimated by CCK8 assay, transwell, scratch assays, and flow cytometry, respectively. The expression levels of ITGB3 were determined by qRT-PCR, western blot, and immunohistochemistry (IHC). Co-immunoprecipitation and Alphafold-Multimer protein complex structure prediction software were employed to identify the molecules that interact with ITGB3.

RESULTS

Cell functional experiments conducted on HTR8/SVneo cells demonstrated that ITGB3 significantly enhanced proliferation, migration, invasion, and adhesion, while simultaneously inhibiting apoptosis. Relative ITGB3 expression levels were observed to be lower in PE placental tissue than in normal tissue and similarly reduced in hypoxic HTR8/SVneo cells. RNA-sequencing data from PE placental samples in the GEO database were analyzed to identify differentially expressed genes associated with the disease. We identified a total of 1460 mRNAs that were significantly differentially expressed in PE patients. Specifically, 798 mRNAs were significantly upregulated, and 662 mRNAs were significantly downregulated. Notably, the ITGB3 exhibited a pronounced down-regulation among the differential expression mRNA.

CONCLUSIONS

This study suggested that ITGB3 plays an important role in promoting the proliferative, migratory, invasive, and adhesive capabilities of trophoblast cells. These findings may facilitate a more in-depth understanding of the molecular mechanisms that promote PE progression.

The role of the JunD-RhoH axis in the pathogenesis of hairy cell leukemia and its ability to identify existing therapeutics that could be repurposed to treat relapsed or refractory disease

Hairy cell leukemia (HCL) is an indolent malignancy of mature B-lymphocytes. While existing front-line therapies achieve excellent initial results, a significant number of patients relapse and become increasingly treatment resistant. A major molecular driver of HCL is aberrant interlocking expression of the transcription factor JunD and the intracellular signaling molecule RhoH. Here we discuss the molecular basis of how the JunD-RhoH axis contributes to HCL pathogenesis. We also discuss how leveraging the JunD-RhoH axis identifies CD23, CD38, CD66a, CD115, CD269, integrin β7, and MET as new potential therapeutic targets. Critically, preclinical studies have already demonstrated that targeting CD38 with isatuximab effectively treats preexisiting HCL. Isatuximab and therapeutics directed against each of the other six new HCL targets are currently in clinical use to treat other disorders. Consequently, leveraging the JunD-RhoH axis has identified a battery of therapies that could be repurposed as new means of treating relapsed or refractory HCL.

Emerging cancer therapies: targeting physiological networks and cellular bioelectrical differences with non-thermal systemic electromagnetic fields in the human body - a comprehensive review

A steadily increasing number of publications support the concept of physiological networks, and how cellular bioelectrical properties drive cell proliferation and cell synchronization. All cells, especially cancer cells, are known to possess characteristic electrical properties critical for physiological behavior, with major differences between normal and cancer cell counterparts. This opportunity can be explored as a novel treatment modality in Oncology. Cancer cells exhibit autonomous oscillations, deviating from normal rhythms. In this context, a shift from a static view of cellular processes is required for a better understanding of the dynamic connections between cellular metabolism, gene expression, cell signaling and membrane polarization as states in constant flux in realistic human models. In oncology, radiofrequency electromagnetic fields have produced sustained responses and improved quality of life in cancer patients with minimal side effects. This review aims to show how non-thermal systemic radiofrequency electromagnetic fields leads to promising therapeutic responses at cellular and tissue levels in humans, supporting this newly emerging cancer treatment modality with early favorable clinical experience specifically in advanced cancer.

Bicistronic Vector Expression of Recombinant Jararhagin-C and Its Effects on Endothelial Cells

Jararhagin-C (JarC) is a protein from the venom of Bothrops jararaca consisting of disintegrin-like and cysteine-rich domains. JarC shows a modulating effect on angiogenesis and remodeling of extracellular matrix constituents, improving wound healing in a mouse experimental model. JarC is purified from crude venom, and the yield is less than 1%. The aim of this work was to obtain the recombinant form of JarC and to test its biological activity. For this purpose, the bicistronic vector pSUMOUlp1 was used. This vector allowed the expression of the recombinant toxin JarC (rJarC) in fusion with the small ubiquitin-related modifier (SUMO) as well as the SUMO protease Ulp1. After expression, this protease was able to efficiently remove SUMO from rJarC inside the bacteria. rJarC free from SUMO was purified at the expected molecular mass and recognized by polyclonal anti-jararhagin antibodies. In terms of biological activity, both the native and recombinant forms showed no toxicity to the HUVEC cell line CRL1730 and were effective in modulating cell migration activity in the experimental in vitro model. These results demonstrate the successful production of rJarC and the preservation of its biological activity, which may facilitate further investigations into the therapeutic potential of this snake venom-derived protein.

Single-cell transcriptomic analysis of glioblastoma reveals pericytes contributing to the blood-brain-tumor barrier and tumor progression

The blood-brain barrier is often altered in glioblastoma (GBM) creating a blood-brain-tumor barrier (BBTB) composed of pericytes. The BBTB affects chemotherapy efficacy. However, the expression signatures of BBTB-associated pericytes remain unclear. We aimed to identify BBTB-associated pericytes in single-cell RNA sequencing data of GBM using pericyte markers, a normal brain pericyte expression signature, and functional enrichment. We identified parathyroid hormone receptor-1 (PTH1R) as a potential marker of pericytes associated with BBTB function. These pericytes interact with other cells in GBM mainly through extracellular matrix-integrin signaling pathways. Compared with normal pericytes, pericytes in GBM exhibited upregulation of several ECM genes (including collagen IV and FN1), and high expression levels of these genes were associated with a poor prognosis. Cell line experiments showed that PTH1R knockdown in pericytes increased collagen IV and FN1 expression levels. In mice models, the expression levels of PTH1R, collagen IV, and FN1 were consistent with these trends. Evans Blue leakage and IgG detection in the brain tissue suggested a negative correlation between PTH1R expression levels and blood-brain barrier function. Further, a risk model based on differentially expressed genes in PTH1R+ pericytes had predictive value for GBM, as validated using independent and in-house cohorts.

Advances in mechanotransduction and sonobiology: effects of audible acoustic waves and low-vibration stimulations on mammalian cells

In recent decades, research on mechanotransduction has advanced considerably, focusing on the effects of audible acoustic waves (AAWs) and low-vibration stimulation (LVS), which has propelled the field of sonobiology forward. Taken together, the current evidence demonstrates the influence of these biosignals on key cellular processes, such as growth, differentiation and migration in mammalian cells, emphasizing the determining role of specific physical parameters during stimulation, such as frequency, sound pressure level/amplitude and exposure time. These mechanical waves interact with various cellular elements, including ion channels, primary cilia, cell-cell adhesion receptors, cell-matrix and extracellular matrix proteins, and focal adhesion complexes. These components connect with the cytoskeletal fibre network, enabling the transmission of mechanical stimuli towards the nucleus. The nucleus, in turn, linked to the cytoskeleton via the linkers of the nucleoskeleton and cytoskeleton complex, acts as a mechanosensitive centre, not only responding to changes in cytoskeletal stiffness and nuclear tension but also regulating gene expression through the transcriptional co-activator YAP/TAZ and interactions between chromatin and the nuclear envelope. This intricate chain of mechanisms highlights the potential of sonobiology in various fields, including dentistry, regenerative medicine, tissue engineering and cancer research. However, progress in these fields requires the establishment of standardized measurement methodologies and biocompatible experimental setups to ensure the reproducibility of results.

Exosomal integrins in tumor progression, treatment and clinical prediction (Review)

Integrins are a large family of cell adhesion molecules involved in tumor cell differentiation, migration, proliferation and neovascularization. Tumor cell‑derived exosomes carry a large number of integrins, which are closely associated with tumor progression. As crucial mediators of intercellular communication, exosomal integrins have gained attention in the field of cancer biology. The present review examined the regulatory mechanisms of exosomal integrins in tumor cell proliferation, migration and invasion, and emphasized their notable roles in tumor initiation and progression. The potential of exosomal integrins as drug delivery systems in cancer treatment was explored. Additionally, the potential of exosomal integrins in clinical tumor prediction was considered, while summarizing their applications in diagnosis, prognosis assessment and treatment response prediction. Thus, the present review aimed to provide guidance and insights for future basic research and the clinical translation of exosomal integrins. The study of exosomal integrins is poised to offer new perspectives and methods for precise cancer treatment and clinical prediction.

Integrin-α9 overexpression underlies the niche-independent maintenance of leukemia stem cells in acute myeloid leukemia

Leukemia stem cells (LSCs) are widely believed to reside in well-characterized bone marrow (BM) niches; however, the capacity of the BM niches to accommodate LSCs is insufficient, and a significant proportion of LSCs are instead maintained in regions outside the BM. The molecular basis for this niche-independent behavior of LSCs remains elusive. Here, we show that integrin-α9 overexpression (ITGA9 OE) plays a pivotal role in the extramedullary maintenance of LSCs by molecularly mimicking the niche-interacting status, through the binding with its soluble ligand, osteopontin (OPN). Retroviral insertional mutagenesis conducted on leukemia-prone Runx-deficient mice identified Itga9 OE as a novel leukemogenic event. Itga9 OE activates Akt and p38MAPK signaling pathways. The elevated Myc expression subsequently enhances ribosomal biogenesis to overcome the cell integrity defect caused by the preexisting Runx alteration. The Itga9-Myc axis, originally discovered in mice, was further confirmed in multiple human acute myeloid leukemia (AML) subtypes, other than RUNX leukemias. In addition, ITGA9 was shown to be a functional LSC marker of the best prognostic value among 14 known LSC markers tested. Notably, the binding of ITGA9 with soluble OPN, a known negative regulator against HSC activation, induced LSC dormancy, while the disruption of ITGA9-soluble OPN interaction caused rapid cell propagation. These findings suggest that the ITGA9 OE increases both actively proliferating leukemia cells and dormant LSCs in a well-balanced manner, thereby maintaining LSCs. The ITGA9 OE would serve as a novel therapeutic target in AML.

Integrin Targeting and Beyond: Enhancing Cancer Treatment with Dual-Targeting RGD (Arginine-Glycine-Aspartate) Strategies

Integrins, an important superfamily of cell adhesion receptors, play an essential role in cancer progression, metastasis, and angiogenesis, establishing them as prime targets for both diagnostic and therapeutic applications. Despite their significant potential, integrin-targeted therapies have faced substantial challenges in clinical trials, including variable efficacy and unmet high expectations. Nevertheless, the consistent expression of integrins on tumor and stromal cells underscores their ongoing relevance and potential. Traditional RGD-based imaging and therapeutic agents have faced limitations, such as inconsistent target expression and rapid systemic clearance, which have reduced their effectiveness. To overcome these challenges, recent research has focused on advancing RGD-based strategies and exploring innovative solutions. This review offers a thorough analysis of the latest developments in the RGD-integrin field, with a particular focus on addressing previous limitations. It delves into new dual-targeting approaches and cutting-edge RGD-based agents designed to improve both tumor diagnosis and therapeutic outcomes. By examining these advancements, this review illuminates new pathways for enhancing the specificity and efficacy of integrin-targeted therapies, paving the way for more effective cancer diagnosis and treatment strategies.

Exploiting Integrin-αVβ3 to Enhance Radiotherapy Efficacy in Medulloblastoma via Ferroptosis

Medulloblastoma, a malignant pediatric brain tumor, has a poor prognosis upon relapse, highlighting a critical clinical need. Our previous research linked medulloblastoma cell radioresistance to integrin-αvβ3 expression. β3-depleted (β3_KO) medulloblastoma cells exhibit lipid hydroxyperoxide accumulation after radiotherapy, indicating ferroptosis, a regulated cell death induced by ROS and inhibited by antioxidants such as cysteine, glutathione (GSH), and glutathione peroxidase 4 (GPx4). However, the link between αvβ3 expression, ferroptosis inhibition, and sensitivity to radiotherapy remains unclear. We showed that irradiated β3_KO medulloblastoma cells primarily die by ferroptosis, with β3-subunit expression correlating with radiotherapy sensitivity and anti-ferroptotic protein levels. Our findings suggest that integrin-αvβ3 signaling boosts oxidative stress resilience via mTORC1. Thus, targeting integrin-αvβ3 could enhance radiotherapy efficacy in medulloblastoma by inducing ferroptotic cell death.

MicroRNAs, endometrial receptivity and molecular pathways

MicroRNAs (miRNAs) are a type of specific molecules that control the activities of the uterus, such as the process of cellular maturing and evolution. A lot of substances like growth factors, cytokines, and transcription factors play a role in embryo-endometrial interaction. MiRNAs could regulate various these factors by attaching to the 3' UTR of their mRNAs. Moreover, current research show that miRNAs participate in formation of blood vessels in endometrium (miR-206, miR-17-5p, miR-16-5p…), decidualization (miR-154, miR-181, miR-9…), epithelial-mesenchymal transition (miR-30a-3p), immune response (miR-888, miR-376a, miR-300…) embryo attachment (miR-145, miR-27a,451…) and pinopod formation (mir-223-3p, mir-449a, mir-200c). In this study, the focus is on the role of miRNAs in managing the uterus' receptivity to an embryo and its ability to facilitate attachment. More specifically, we are exploring the mechanisms by which miRNAs regulate the presence of specific molecules involved in this crucial physiological process.

Moojecin: The first disintegrin from Bothrops moojeni venom and its antitumor activity in acute myeloid leukemia

Disintegrins are a class of peptides found in snake venom that inhibit the activity of integrins, which are essential cell adhesion receptors in tumor progression and development. In this work, moojecin, a RGD disintegrin, was isolated from Bothrops moojeni snake venom, and its antitumor potential in acute myeloid leukemia (AML) HL-60 and THP-1 cells was characterized. The isolation was performed using a C18 reverse-phase column in two chromatographic steps, and its molecular mass is 7417.84 Da. N-terminal and de novo sequencing was performed to identify moojecin. Moojecin did not show cytotoxic or antiproliferative activity in THP-1 and HL-60 at tested concentrations, but it exhibited significant antimigratory activity in both cell lines, as well as inhibition of angiogenesis in the tube formation assay on Matrigel in a dose-dependent manner. A stronger interaction with integrin αVβ3 was shown in integrin interaction assays compared to α5β1, and the platelet aggregation assay indicated an IC50 of 5.039 μg/mL. Preliminary evaluation of disintegrin toxicity revealed no incidence of hemolysis or cytotoxic effects on peripheral blood mononuclear cells (PBMCs) across the tested concentrations. Thus, this is the first study to report the isolation, functional and structural characterization of a disintegrin from B. moojeni venom and bring a new perspective to assist in AML treatment.

Attachment promoting compounds significantly enhance cell proliferation and purity of bovine satellite cells grown on microcarriers in the absence of serum

Introduction

To bring cultivated beef to the market, a scalable system that can support growth of bovine satellite cells (bSCs) in a serum-free and preferably also animal-free medium is of utmost importance. The use of microcarriers (MCs) is, at the moment, one of the most promising technologies for scaling up. MCs offer a large surface to volume ratio, they can be used in scalable stirred tank bioreactors, where the culture conditions can be tightly controlled to meet the cells' requirements (temperature, pH, dissolved oxygen). The inherent capacity of the cells to migrate from one MC to another, also known as bead-to-bead transfer, facilitates a scale-up strategy involving MCs. Previous studies have shown growth of bSCs on three commercially available MCs in serum containing media. Unfortunately there is currently no information available regarding their growth on MCs in serum-free conditions.

Methods

In this study, we aimed to find suitable serum-free media, MCs and attachment promoting compounds (APCs) supporting the growth of bSCs. Initially, six commercial MCs and three serum-free media were evaluated. The effects of three APCs were compared (vitronectin, laminin and fibronectin). Subsequently, the effects of different concentrations and modes of addition of the best performing APC were investigated.

Results and Discussion

Our results showed that Cytodex 1, Synthemax II and CellBIND supported bSCs' growth in all serum-free media. Overall, better growth was observed with Cytodex 1 in serum-free proliferation media. We showed that the use of laminin or vitronectin with Cytodex 1 can significantly improve cell growth and purity. Laminin also allowed attachment and growth of bSCs on Plastic MCs which had been previously unsuccessful without APCs. Finally, we optimized the use of vitronectin from a sustainability and process perspective, and showed that it can be used solely as a coating for Cytodex 1 (16-100 ng/cm2) MCs, instead of as a medium supplement, enhancing cell attachment and proliferation.

Functions for platelet factor 4 (PF4/CXCL4) and its receptors in fibroblast-myofibroblast transition and fibrotic failure of arteriovenous fistulas (AVFs)

BACKGROUND

Over 60% of End Stage Renal Disease (ESRD) patients are relying on hemodialysis (HD) to survive, and the arteriovenous fistula (AVF) is the preferred vascular access method for HD. However approximately half of all newly created AVF fail to mature and cannot be used without a salvage procedure. We have recently demonstrated an association between AVF maturation failure and post-operative fibrosis, while our RNA-seq study also revealed that veins that ultimately failed during AVF maturation had elevated levels of platelet factor 4 (PF4/CXCL4). However, a link between these two findings was yet to be established.

METHODS

In this study, we investigated potential mechanisms between PF4 levels and fibrotic remodeling in veins. We compared the local expression of PF4 and fibrosis marker integrin β6 (ITGB6) in veins that successfully underwent maturation with that in veins that ultimately failed to mature. We also measured the changes of expression level of α-smooth muscle actin (αSMA/ACTA2) and collagen (Col1/COL1A1) in venous fibroblasts upon various treatments, such as PF4 pharmacological treatment, alteration of PF4 expression, and blocking of PF4 receptors.

RESULTS

We found that PF4 is expressed in veins and co-localizes with αSMA. In venous fibroblasts, PF4 stimulates expression of αSMA and Col1 via different pathways. The former requires integrins αvβ5 and α5β1, while chemokine receptor CXCR3 is needed for the latter. Interestingly, we also discovered that the expression of PF4 is associated with that of ITGB6, the β subunit of integrin αvβ6. This integrin is critical for the activation of the major fibrosis factor TGFβ, and overexpression of PF4 promotes activation of the TGFβ pathway.

CONCLUSIONS

These results indicate that upregulation of PF4 may cause venous fibrosis both directly by stimulating fibroblast differentiation and expression of extracellular matrix (ECM) molecules and indirectly by facilitating the activation of the TGFβ pathway.

Acute contact with profibrotic macrophages mechanically activates fibroblasts via αvβ3 integrin-mediated engagement of Piezo1

Fibrosis-excessive scarring after injury-causes >40% of disease-related deaths worldwide. In this misguided repair process, activated fibroblasts drive the destruction of organ architecture by accumulating and contracting extracellular matrix. The resulting stiff scar tissue, in turn, enhances fibroblast contraction-bearing the question of how this positive feedback loop begins. We show that direct contact with profibrotic but not proinflammatory macrophages triggers acute fibroblast contractions. The contractile response depends on αvβ3 integrin expression on macrophages and Piezo1 expression on fibroblasts. The touch of macrophages elevates fibroblast cytosolic calcium within seconds, followed by translocation of the transcription cofactors nuclear factor of activated T cells 1 and Yes-associated protein, which drive fibroblast activation within hours. Intriguingly, macrophages induce mechanical stress in fibroblasts on soft matrix that alone suppresses their spontaneous activation. We propose that acute contact with suitable macrophages mechanically kick-starts fibroblast activation in an otherwise nonpermissive soft environment. The molecular components mediating macrophage-fibroblast mechanotransduction are potential targets for antifibrosis strategies.

Mechanosensory entities and functionality of endothelial cells

The endothelial cells of the blood circulation are exposed to hemodynamic forces, such as cyclic strain, hydrostatic forces, and shear stress caused by the blood fluid's frictional force. Endothelial cells perceive mechanical forces via mechanosensors and thus elicit physiological reactions such as alterations in vessel width. The mechanosensors considered comprise ion channels, structures linked to the plasma membrane, cytoskeletal spectrin scaffold, mechanoreceptors, and junctional proteins. This review focuses on endothelial mechanosensors and how they alter the vascular functions of endothelial cells. The current state of knowledge on the dysregulation of endothelial mechanosensitivity in disease is briefly presented. The interplay in mechanical perception between endothelial cells and vascular smooth muscle cells is briefly outlined. Finally, future research avenues are highlighted, which are necessary to overcome existing limitations.

Oncomatrix: Molecular Composition and Biomechanical Properties of the Extracellular Matrix in Human Tumors

The extracellular matrix is an organized three-dimensional network of protein-based molecules and other macromolecules that provide structural and biochemical support to tissues. Depending on its biochemical and structural properties, the extracellular matrix influences cell adhesion and signal transduction and, in general, can influence cell differentiation and proliferation through specific mechanisms of chemical and mechanical sensing. The development of body tissues during ontogenesis is accompanied by changes not only in cells but also in the composition and properties of the extracellular matrix. Similarly, tumor development in carcinogenesis is accompanied by a continuous change in the properties of the extracellular matrix of tumor cells, called ‘oncomatrix’, as the tumor matures, from the development of the primary focus to the stage of metastasis. In this paper, the characteristics of the composition and properties of the extracellular matrix of tumor tissues are considered, as well as changes to the composition and properties of the matrix during the evolution of the tumor and metastasis. The extracellular matrix patterns of tumor tissues can be used as biomarkers of oncological diseases as well as potential targets for promising anti-tumor therapies.

SARS-CoV-2 spike protein potentiates platelet aggregation via upregulating integrin αIIbβ3 outside-in signaling pathway

Platelet hyperreactivity is one of the crucial causes of coagulative disorders in patients with COVID-19. Few studies have indicated that integrin αIIbβ3 may be a potential target for spike protein binding to platelets. This study aims to investigate whether spike protein interacts with platelet integrin αIIbβ3 and upregulates outside-in signaling to potentiate platelet aggregation. In this study, we found that spike protein significantly potentiated platelet aggregation induced by different agonists and platelet spreading in vitro. Mechanism studies revealed that spike protein upregulated the outside-in signaling, such as increased thrombin-induced phosphorylation of β3, c-Src. Moreover, using tirofiban to inhibit spike protein binding to αIIbβ3 or using PP2 to block outside-in signaling, we found that the potentiating effect of spike protein on platelet aggregation was abolished. These results demonstrate that SARS-CoV-2 spike protein directly enhances platelet aggregation via integrin αIIbβ3 outside-in signaling, and suggest a potential target for platelet hyperreactivity in patients with COVID-19. HIGHLIGHTS: • Spike protein potentiates platelet aggregation and upregulates αIIbβ3 outside-in signaling. • Spike protein interacts with integrin αIIbβ3 to potentiate platelet aggregation. • Blocking outside-in signaling abolishes the effect of spike protein on platelets.

YIGSR, A Laminin-Derived Peptide, Dictates a Concentration-Dependent Impact on Macrophage Phenotype Response

Purpose

Macrophage immune cells play crucial roles in the inflammatory (M1) and regenerative (M2) processes. The extracellular matrix (ECM) composition, including presentation of embedded ligands, governs macrophage function. Laminin concentration is abundant in the basement membrane and is dependent on pathological state: reduced in inflammation and increased during regeneration. Distinct laminin ligands, such as IKVAV and YIGSR, have disparate roles in dictating cell function. For example, IKVAV, derived from the alpha chain of laminin, promotes angiogenesis and metastasis of cancer cells whereas YIGSR, beta chain derived, impedes angiogenesis and tumor progression. Previous work has demonstrated IKVAV's inflammation inhibiting properties in macrophages. Given the divergent role of IKVAV and YIGSR in interacting with cells through varied integrin receptors, we ask: what role does laminin derived peptide YIGSR play in governing macrophage function?

Methods

We quantified the influence of YIGSR on macrophage phenotype in 2D and 3D via immunostaining assessments for M1 marker inducible nitric oxide synthase (iNOS) and M2 marker Arginase-1 (Arg-1). We also analysed the secretome of human and murine macrophage response to YIGSR via a Luminex bead assay.

Results

YIGSR impact on macrophage phenotype occurs in a concentration-dependent manner. At lower concentrations of YIGSR, macrophage inflammation was increased whereas, at higher concentrations of YIGSR the opposite effect was seen within the same time frame. Secretomic assessments also demonstrate that pro-inflammatory chemokines and cytokines were increased at low YIGSR concentrations in M0, M1, M2 macrophages while pro-inflammatory secretion was reduced at higher concentrations.

Conclusions

YIGSR can be used as a tool to modulate macrophage inflammatory state within M1 and M2 phenotypes depending on the concentration of peptide. YIGSR's impact on macrophage function can be leveraged for the development of immunoengineering strategies in regenerative medicine and cancer therapy.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12195-024-00810-5.

YKL40/Integrin β4 Axis Induced by the Interaction between Cancer Cells and Tumor-Associated Macrophages Is Involved in the Progression of High-Grade Serous Ovarian Carcinoma

Macrophages in the tumor microenvironment, termed tumor-associated macrophages (TAMs), promote the progression of various cancer types. However, many mechanisms related to tumor-stromal interactions in epithelial ovarian cancer (EOC) progression remain unclear. High-grade serous ovarian carcinoma (HGSOC) is the most malignant EOC subtype. Herein, immunohistochemistry was performed on 65 HGSOC tissue samples, revealing that patients with a higher infiltration of CD68+, CD163+, and CD204+ macrophages had a poorer prognosis. We subsequently established an indirect co-culture system between macrophages and EOC cells, including HGSOC cells. The co-cultured macrophages showed increased expression of the TAM markers CD163 and CD204, and the co-cultured EOC cells exhibited enhanced proliferation, migration, and invasion. Cytokine array analysis revealed higher YKL40 secretion in the indirect co-culture system. The addition of YKL40 increased proliferation, migration, and invasion via extracellular signal-regulated kinase (Erk) signaling in EOC cells. The knockdown of integrin β4, one of the YKL40 receptors, suppressed YKL40-induced proliferation, migration, and invasion, as well as Erk phosphorylation in some EOC cells. Database analysis showed that high-level expression of YKL40 and integrin β4 correlated with a poor prognosis in patients with serous ovarian carcinoma. Therefore, the YKL40/integrin β4 axis may play a role in ovarian cancer progression.

Low Intraocular Pressure Induces Fibrotic Changes in the Trabecular Meshwork and Schlemm's Canal of Sprague Dawley Rats

Purpose

Continuous artificial aqueous humor drainage in the eyes of patients with glaucoma undergoing trabeculectomy likely exerts abnormal shear stress. However, it remains unknown how changes in intraocular pressure (IOP) can affect aqueous humor outflow (AHO).

Methods

Here, we induced and maintained low intraocular pressure (L-IOP) in healthy Sprague Dawley (SD) rats by puncturing their eyes using a tube (200-µm diameter) for 2 weeks. After the rats were euthanized, their eyes were removed, fixed, embedded, stained, and scanned to analyze the physiological and pathological changes in the trabecular meshwork (TM) and Schlemm's canal (SC). We measured SC parameters using ImageJ software and assessed the expression of various markers related to flow shear stress (KLF4), fibrosis (TGF-β1, TGF-β2, α-SMA, pSmad1/5, pSmad2/3, and fibronectin), cytoskeleton (integrin β1 and F-actin), diastolic function (nitric oxide synthase and endothelial nitric oxide synthase [eNOS]), apoptosis (cleaved caspase-3), and proliferation (Ki-67) using immunofluorescence or immunohistochemistry.

Results

L-IOP eyes showed a larger SC area, higher eNOS expression, and lower KLF4 and F-actin expression in the TM and SC (both P < 0.05) than control eyes. The aqueous humor of L-IOP eyes had a higher abundance of fibrotic proteins and apoptotic cells than that of control eyes, with significantly higher TGF-β1, α-SMA, fibronectin, and cleaved caspase-3 expression (all P < 0.05).

Conclusions

In conclusion, a persistence of L-IOP for 2 weeks may contribute to fibrosis in the TM and SC and might be detrimental to conventional AHO in SD rat eyes.

Translational Relevance

Clinicians should consider that aberrant shear force induced by aqueous humor fluctuation may damage AHO outflow channel when treating patients.

Anoikis in cell fate, physiopathology, and therapeutic interventions

The extracellular matrix (ECM) governs a wide spectrum of cellular fate processes, with a particular emphasis on anoikis, an integrin-dependent form of cell death. Currently, anoikis is defined as an intrinsic apoptosis. In contrast to traditional apoptosis and necroptosis, integrin correlates ECM signaling with intracellular signaling cascades, describing the full process of anoikis. However, anoikis is frequently overlooked in physiological and pathological processes as well as traditional in vitro research models. In this review, we summarized the role of anoikis in physiological and pathological processes, spanning embryonic development, organ development, tissue repair, inflammatory responses, cardiovascular diseases, tumor metastasis, and so on. Similarly, in the realm of stem cell research focused on the functional evolution of cells, anoikis offers a potential solution to various challenges, including in vitro cell culture models, stem cell therapy, cell transplantation, and engineering applications, which are largely based on the regulation of cell fate by anoikis. More importantly, the regulatory mechanisms of anoikis based on molecular processes and ECM signaling will provide new strategies for therapeutic interventions (drug therapy and cell-based therapy) in disease. In summary, this review provides a systematic elaboration of anoikis, thus shedding light on its future research.

Structural insights into the molecular recognition of integrin αVβ3 by RGD-containing ligands: The role of the specificity-determining loop (SDL)

Integrin αVβ3 is a prominent member of the "RGD-recognizing" integrin family of cell surface receptors. αVβ3 binds to various extracellular matrix (ECM) proteins and oxysterols such as 25-hydroxycholesterol, is implicated in several diseases, including cancer metastasis, lung fibrosis, inflammation, and autoimmune diseases, and is pursued as a valuable therapeutic target. Despite enormous efforts to seek a pure antagonist, to date, no single drug candidate has successfully reached clinics due to associated partial agonism and toxicity issues. Developing effective and safe inhibitors require a thorough understanding of the molecular interactions and structural changes related to the receptor's activation and inhibition mechanisms. This study offers a comprehensive residue-residue contact and network analyses of the ligand-binding β-propeller βI domains (headpiece) based on all available experimental structures of integrin αVβ3 in unliganded, agonist-, antagonist-, and antibody-bound states. The analyses reveal many critical interactions that were not reported before and show that specific orientation and interactions of residues from the specificity-determining loop (SDL) are critical in molecular recognition and regulation. Also, the network analysis reveals that residues from the nearby allosteric site (site II) connect to the primary RGD-binding site via SDL, which likely acts as an interface between the two sites. Our results provide valuable insights into molecular interactions, structural changes, distinct features of the active and inactive headpiece conformations, the role of SDL in ligand recognition, and SDL-mediated allostery. Thus, the insights from this study may facilitate the designing of pure antagonists or site II-mediated allosteric modulators to integrin αVβ3 to treat various diseases.

Family-Wide Photoproximity Profiling of Integrin Protein Social Networks in Cancer

Integrin family transmembrane receptors mediate dynamic interactions between cells and their extracellular microenvironment. The heterogeneous interaction partners of integrins directly regulate cell adhesion, motility, proliferation, and intracellular signaling. Despite the recognized importance of protein-protein interactions and the formation of signaling hubs around integrins, the ability to detect and quantify these dynamic binding partners with high spatial and temporal resolution remains challenging. Here, we developed an integrin-family-directed quantitative photoproximity protein interaction (PhotoPPI) profiling method to detect and quantify native integrin-centered protein social networks on live cells and tissues without the need for genetic manipulation, antibodies, or non-physiologic cell culture conditions. We drafted quantitative maps of integrin-centered protein social networks, highlighting conserved and unique binding partners between different cell types and cellular microenvironments. Comparison of integrin social networks in cancer cell lines of diverse tissue of origin and disease state identified specific AND-gate binding partners involved cell migration, microenvironmental interactions and proliferation that serve as markers of tumor cell metastatic state. Finally, we identified unique combinations - or barcodes - of integrin-proximal proteins on the surface of pre- and post-metastatic triple negative breast cancer (TNBC) cells whose expression strongly correlate with both positive and negative disease progression and outcomes in TNBC patients. Taken together, these data provide the first family-wide high-resolution maps of native protein interactors on live cells and identify dynamic integrin-centered social networks as potential AND-gate markers of cell identity, microenvironmental context and disease state.

Netrin-1 and UNC5B Cooperate with Integrins to Mediate YAP-Driven Cytostasis

Opposite expression and pro- or anti-cancer function of YAP and its paralog TAZ/WWTR1 stratify cancers into binary YAPon and YAPoff classes. These transcriptional coactivators are oncogenic in YAPon cancers. In contrast, YAP/TAZ are silenced epigenetically along with their integrin and extracellular matrix adhesion target genes in neural and neuroendocrine YAPoff cancers (e.g., small cell lung cancer, retinoblastoma). Forced YAP/TAZ expression induces these targets, causing cytostasis in part through Integrin-αV/β5, independent of the integrin-binding RGD ligand. Other effectors of this anticancer YAP function are unknown. Here, using clustered regularly interspaced short palindromic repeats (CRISPR) screens, we link the Netrin receptor UNC5B to YAP-induced cytostasis in YAPoff cancers. Forced YAP expression induces UNC5B through TEAD DNA-binding partners, as either TEAD1/4-loss or a YAP mutation that disrupts TEAD-binding (S94A) blocks, whereas a TEAD-activator fusion (TEAD(DBD)-VP64) promotes UNC5B induction. Ectopic YAP expression also upregulates UNC5B relatives and their netrin ligands in YAPoff cancers. Netrins are considered protumorigenic, but knockout and peptide/decoy receptor blocking assays reveal that in YAPoff cancers, UNC5B and Netrin-1 can cooperate with integrin-αV/β5 to mediate YAP-induced cytostasis. These data pinpoint an unsuspected Netrin-1/UNC5B/integrin-αV/β5 axis as a critical effector of YAP tumor suppressor activity.

SIGNIFICANCE

Netrins are widely perceived as procancer proteins; however, we uncover an anticancer function for Netrin-1 and its receptor UNC5B.

The role of integrins in brain health and neurodegenerative diseases

Integrins are heterodimeric membrane proteins expressed on the surface of most cells. They mediate adhesion and signaling processes relevant for a wealth of physiological processes, including nervous system development and function. Interestingly, integrins are also recognized therapeutic targets for inflammatory diseases, such as multiple sclerosis. Here, we discuss the role of integrins in brain development and function, as well as in neurodegenerative diseases affecting the brain (Alzheimer's disease, multiple sclerosis, stroke). Furthermore, we discuss therapeutic targeting of these adhesion receptors in inflammatory diseases of the brain.

Inhibition of BMP-mediated SMAD pathway supports the pluripotency of pig embryonic stem cells in the absence of feeder cells

Here, we examined the effects of the BMP signaling pathway inhibitor LDN-193189 on the pluripotency of porcine embryonic stem cells (ESCs) in the absence of feeder cells using molecular and transcriptomic techniques. Additionally, the effects of some extracellular matrix components on porcine ESC pluripotency were evaluated to develop an optimized and sustainable feeder-free culture system for porcine ESCs. Feeder cells were found to play an important role in supporting the pluripotency of porcine ESCs by blocking trophoblast and mesodermal differentiation through the inhibition of the BMP pathway. Additionally, treatment with LDN-193189, an inhibitor of the BMP pathway, maintained the pluripotency and homogeneity of porcine ESCs for an extended period in the absence of feeder cells by stimulating the secretion of chemokines and suppressing differentiation, based on transcriptome analysis. Conclusively, these results suggest that LDN-193189 could be a suitable replacement for feeder cells in the maintenance of porcine ESC pluripotency during culture. Additionally, these findings contribute to the understanding of pluripotency gene networks and comparative embryogenesis.

Adhesion of retinal cells to gold surfaces by biomimetic molecules

Background

Neural cell-electrode coupling is crucial for effective neural and retinal prostheses. Enhancing this coupling can be achieved through surface modification and geometrical design to increase neuron-electrode proximity. In the current research, we focused on designing and studying various biomolecules as a method to elicit neural cell-electrode adhesion via cell-specific integrin mechanisms.

Methods

We designed extracellular matrix biomimetic molecules with different head sequences (RGD or YIGSR), structures (linear or cyclic), and spacer lengths (short or long). These molecules, anchored by a thiol (SH) group, were deposited onto gold surfaces at various concentrations. We assessed the modifications using contact angle measurements, fluorescence imaging, and X-ray Photoelectron Spectroscopy (XPS). We then analyzed the adhesion of retinal cells and HEK293 cells to the modified surfaces by measuring cell density, surface area, and focal adhesion spots, and examined changes in adhesion-related gene and integrin expression.

Results

Results showed that YIGSR biomolecules significantly enhanced retinal cell adhesion, regardless of spacer length. For HEK293 cells, RGD biomolecules were more effective, especially with cyclic RGD and long spacers. Both cell types showed increased expression of specific adhesion integrins and proteins like vinculin and PTK2; these results were in agreement with the adhesion studies, confirming the cell-specific interactions with modified surfaces.

Conclusion

This study highlights the importance of tailored biomolecules for improving neural cell adhesion to electrodes. By customizing biomolecules to foster specific and effective interactions with adhesion integrins, our study provides valuable insights for enhancing the integration and functionality of retinal prostheses and other neural implants.

Integrins in cancer stem cells

Integrins are a class of adhesion receptors on cell membranes, consisting of α and β subunits. By binding to the extracellular matrix, integrins activate intracellular signaling pathways, participating in every step of cancer initiation and progression. Tumor stem cells possess self-renewal and self-differentiation abilities, along with strong tumorigenic potential. In this review, we discussed the role of integrins in cancer, with a focus on their impact on tumor stem cells and tumor stemness. This will aid in targeting tumor stem cells as a therapeutic approach, leading to the exploration of novel cancer treatment strategies.

Cryo-EM structure of I domain-containing integrin αEβ7

The integrin family is a transmembrane receptor that plays critical roles in the cell-cell and cell-extracellular matrix adhesion, signal transduction such as cell cycle regulation, organization of the intracellular cytoskeleton, and immune responses. Consequently, dysfunction of integrins is associated with a wide range of human diseases, including cancer and immune diseases, which makes integrins therapeutic targets for drug discovery. Here we report the cryo-EM structure of the human α-I domain-containing full-length integrin αEβ7, which is expressed in the leukocytes of the immune system and a drug target for inflammatory bowel disease (IBD). The structure reveals the half-bent conformation, an intermediate between the close and the open conformation, while the α-I domain responsible for the ligand binding covers the headpiece domain by a unique spatial arrangement. Our results provide the structural information for the drug design targeting IBD.

Y chromosome linked UTY modulates sex differences in valvular fibroblast methylation in response to nanoscale extracellular matrix cues

Aortic valve stenosis (AVS) is a progressive disease wherein males more often develop valve calcification relative to females that develop valve fibrosis. Valvular interstitial cells (VICs) aberrantly activate to myofibroblasts during AVS, driving the fibrotic valve phenotype in females. Myofibroblasts further differentiate into osteoblast-like cells and produce calcium nanoparticles, driving valve calcification in males. We hypothesized the lysine demethylase UTY (ubiquitously transcribed tetratricopeptide repeat containing, Y-linked) decreases methylation uniquely in male VICs responding to nanoscale extracellular matrix cues to promote an osteoblast-like cell phenotype. Here, we describe a hydrogel biomaterial cell culture platform to interrogate how nanoscale cues modulate sex-specific methylation states in VICs activating to myofibroblasts and osteoblast-like cells. We found UTY modulates the osteoblast-like cell phenotype in response to nanoscale cues uniquely in male VICs. Overall, we reveal a novel role of UTY in the regulation of calcification processes in males during AVS progression.

β2-Integrins Regulate Microglial Responses and the Functional Outcome of Hemorrhagic Stroke In Vivo

Stroke is one of the leading causes of death and long-term disabilities worldwide. In addition to interruption of blood flow, inflammation is widely recognized as an important factor mediating tissue destruction in stroke. Depending on their phenotype, microglia, the main leukocytes in the CNS, are capable of either causing further tissue damage or promoting brain restoration after stroke. β2-integrins are cell adhesion molecules that are constitutively expressed on microglia. The function of β2-integrins has been investigated extensively in animal models of ischemic stroke, but their role in hemorrhagic stroke is currently poorly understood. We show in this study that dysfunction of β2-integrins is associated with improved functional outcome and decreased inflammatory cytokine expression in the brain in a mouse model of hemorrhagic stroke. Furthermore, β2-integrins affect microglial phenotype and cytokine responses in vivo. Therefore, our findings suggest that targeting β2-integrins in hemorrhagic stroke may be beneficial.

Molecular Determinants for Photodynamic Therapy Resistance and Improved Photosensitizer Delivery in Glioma

Gliomas account for 24% of all the primary brain and Central Nervous System (CNS) tumors. These tumors are diverse in cellular origin, genetic profile, and morphology but collectively have one of the most dismal prognoses of all cancers. Work is constantly underway to discover a new effective form of glioma therapy. Photodynamic therapy (PDT) may be one of them. It involves the local or systemic application of a photosensitive compound-a photosensitizer (PS)-which accumulates in the affected tissues. Photosensitizer molecules absorb light of the appropriate wavelength, initiating the activation processes leading to the formation of reactive oxygen species and the selective destruction of inappropriate cells. Research focusing on the effective use of PDT in glioma therapy is already underway with promising results. In our work, we provide detailed insights into the molecular changes in glioma after photodynamic therapy. We describe a number of molecules that may contribute to the resistance of glioma cells to PDT, such as the adenosine triphosphate (ATP)-binding cassette efflux transporter G2, glutathione, ferrochelatase, heme oxygenase, and hypoxia-inducible factor 1. We identify molecular targets that can be used to improve the photosensitizer delivery to glioma cells, such as the epithelial growth factor receptor, neuropilin-1, low-density lipoprotein receptor, and neuropeptide Y receptors. We note that PDT can increase the expression of some molecules that reduce the effectiveness of therapy, such as Vascular endothelial growth factor (VEGF), glutamate, and nitric oxide. However, the scientific literature lacks clear data on the effects of PDT on many of the molecules described, and the available reports are often contradictory. In our work, we highlight the gaps in this knowledge and point to directions for further research that may enhance the efficacy of PDT in the treatment of glioma.

Extracellular matrix rigidity modulates physical properties of subcapsular sinus macrophage-B cell immune synapses

Subcapsular sinus macrophages (SSMs) play a key role in immune defense by forming immunological barriers that control the transport of antigens from lymph into lymph node follicles. SSMs participate in antibody responses by presenting antigens directly to naive B cells and by supplying antigens to follicular dendritic cells to propagate germinal center reactions. Despite the prominent roles that SSMs play during immune responses, little is known about their cell biology because they are technically challenging to isolate and study in vitro. Here, we used multicolor fluorescence microscopy to identify lymph node-derived SSMs in culture. We focused on the role of SSMs as antigen-presenting cells, and found that their actin cytoskeleton regulates the spatial organization and mobility of multivalent antigens (immune complexes [ICs]) displayed on the cell surface. Moreover, we determined that SSMs are mechanosensitive cells that respond to changes in extracellular matrix rigidity by altering the architecture of the actin cytoskeleton, leading to changes in cell morphology, membrane topography, and IC mobility. Changes to extracellular matrix rigidity also modulate actin remodeling by both SSMs and B cells when they form an immune synapse. This alters synapse duration but not IC internalization nor NF-κB activation in the B cell. Taken together, our data reveal that the mechanical microenvironment may influence B cell responses by modulating physical characteristics of antigen presentation by SSMs.

A novel surface marker CD49d promotes TNF expression in oyster agranulocytes by mediating the MAPK pathway

CD49d, encoded by the gene Integrin α4, is a significant member of cell adhesion receptors, which is widely expressed in various immune cells to trigger immune responses against invading pathogens. In the present study, the expression of CgCD49d and its regulatory role in TNF expression were investigated in the Pacific oyster Crassostrea gigas. There were five Int-alpha domains, an Integrin_alpha2 region and a unique FG-GAP repeat region inserted identified in CgCD49d. CgCD49d transcript was specifically expressed in haemocytes, and its mRNA expression level in haemocytes increased after LPS and Vibrio splendidus stimulation. After CgCD49d was blocked by using its antibody, the phosphorylation level of CgJNK in the MAPK signaling pathway and CgTNF transcripts decreased significantly post V. splendidus stimulation. After phosphorylation level of CgJNK was inhibited by using its inhibitor, the nuclear translocation of CgRel was restrained and CgTNF transcripts also decreased significantly post V. splendidus stimulation. Furthermore, CgCD49d was found to be mainly expressed in the agranulocyte subpopulation, and Alexa Fluor 488-conjugated CgCD49d antibody labeled agranulocytes with a circle of green fluorescence signals on CgCD49d+ agranulocyte surface under Confocal microscopy, which accounted for 24.9 ± 4.53% of total haemocytes. Collectively, these results suggested that CgCD49d promoted TNF expression in oyster haemocytes against bacterial invasion by mediating MAPK pathway, and it could be used as a surface marker to type and sort a subset of agranulocyte subpopulation among haemocytes.

3D Culture Analysis of Cancer Cell Adherence to Ex Vivo Lung Microexplants

Ex vivo 3D culture of human tissue explants addresses many limitations of traditional monolayer cell culture techniques, namely the lack of cellular heterogeneity and absence of 3D intercellular spatial relationships, but presents challenges with regard to repeatability owing to the difficulty of acquiring multiple tissue samples from the same donor. In this study, we used a cryopreserved bank of human lung microexplants, ∼1 mm3 fragments of peripheral lung from donors undergoing lung resection surgery, and a liquid-like solid 3D culture matrix to describe a method for the analysis of non-small-cell lung cancer adhesion to human lung tissue. H226 (squamous cell carcinoma), H441 (lung adenocarcinoma), and H460 (large cell carcinoma) cell lines were cocultured with lung microexplants. Confocal fluorescence microscopy was used to visualize the adherence of each cell line to lung microexplants. Adherent cancer cells were quantified following filtration of nonadherent cells, digestion of cultured microexplants, and flow cytometry. This method was used to evaluate the role of integrins in cancer cell adherence. A statistically significant decrease in the adherence of H460 cells to lung microexplants was observed when anti-integrins were administered to H460 cells before coculture with lung microexplants.

Whole-exome sequencing screening for candidate genes and variants associated with primary sporadic keratoconus in Chinese patients

The pathogenesis of keratoconus (KC) is complex, and genetic factors play an important role. The purpose of this study was to screen and analyse candidate genes and variants in Chinese patients with primary sporadic KC. Whole-exome sequencing (WES) was performed to identify candidate genes and variants in 105 unrelated Chinese patients with primary sporadic KC. Through a series of screening processes, 54 candidate variants in 26 KC candidate genes were identified in 53 KC patients (53/105, 50.5%). These 54 candidate variants included 10 previously identified variants in 9 KC candidate genes and 44 novel variants in 20 KC candidate genes. The previously identified variants occurred in 25.7% (27/105) of patients. Of these, 4 variants (COL6A5, c.5014T > G; CAST, c.1814G > A; ZNF469, c.946G > A; and MPDZ, c.3836A > G) were identified for the first time in Chinese KC patients. The novel variants occurred in 33.3% (35/105) of patients. Of the 26 screened KC candidate genes, 11 KC candidate genes (CAT, COL12A1, FLG, HKDC1, HSPG2, PLOD1, ITGA2, TFAP2B, USH2A, WNT10A, and COL6A5) were found to be potentially pathogenic in Chinese KC patients for the first time. Gene Ontology (GO) biological process (BP) enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway analysis were performed on the 26 KC candidate genes using the Database for Annotation, Visualization, and Integrated Discovery (DAVID). The results showed that the KC candidate genes were significantly enriched in biological processes such as collagen fibril organization and extracellular matrix (ECM) organization and in ECM-receptor interaction and protein digestion and absorption pathways. The results further expand the spectrum of KC candidate variants and provide a basis for further KC gene studies.

FGF1 Suppresses Allosteric Activation of β3 Integrins by FGF2: A Potential Mechanism of Anti-Inflammatory and Anti-Thrombotic Action of FGF1

Several inflammatory cytokines bind to the allosteric site (site 2) and allosterically activate integrins. Site 2 is also a binding site for 25-hydroxycholesterol, an inflammatory lipid mediator, and is involved in inflammatory signaling (e.g., TNF and IL-6 secretion) in addition to integrin activation. FGF2 is pro-inflammatory and pro-thrombotic, and FGF1, homologous to FGF2, has anti-inflammatory and anti-thrombotic actions, but the mechanism of these actions is unknown. We hypothesized that FGF2 and FGF1 bind to site 2 of integrins and regulate inflammatory signaling. Here, we describe that FGF2 is bound to site 2 and allosterically activated β3 integrins, suggesting that the pro-inflammatory action of FGF2 is mediated by binding to site 2. In contrast, FGF1 bound to site 2 but did not activate these integrins and instead suppressed integrin activation induced by FGF2, indicating that FGF1 acts as an antagonist of site 2 and that the anti-inflammatory action of FGF1 is mediated by blocking site 2. A non-mitogenic FGF1 mutant (R50E), which is defective in binding to site 1 of αvβ3, suppressed β3 integrin activation by FGF2 as effectively as WT FGF1.

Integrins as a bridge between bacteria and cells: key targets for therapeutic wound healing

Integrins are heterodimers composed of α and β subunits that are bonded through non-covalent interactions. Integrins mediate the dynamic connection between extracellular adhesion molecules and the intracellular actin cytoskeleton. Integrins are present in various tissues and organs where these heterodimers participate in diverse physiological and pathological responses at the molecular level in living organisms. Wound healing is a crucial process in the recovery from traumatic diseases and comprises three overlapping phases: inflammation, proliferation and remodeling. Integrins are regulated during the entire wound healing process to enhance processes such as inflammation, angiogenesis and re-epithelialization. Prolonged inflammation may result in failure of wound healing, leading to conditions such as chronic wounds. Bacterial colonization of a wound is one of the primary causes of chronic wounds. Integrins facilitate the infectious effects of bacteria on the host organism, leading to chronic inflammation, bacterial colonization, and ultimately, the failure of wound healing. The present study investigated the role of integrins as bridges for bacteria-cell interactions during wound healing, evaluated the role of integrins as nodes for bacterial inhibition during chronic wound formation, and discussed the challenges and prospects of using integrins as therapeutic targets in wound healing.