Search Results (78)

This study aims to evaluate the therapeutic efficacy of emodin (EMO) in rheumatoid arthritis (RA) and to verify whether its underlying mechanism involves the blockade of pathological angiogenesis via the inhibition of the nuclear factor-kappa B (NF-κB)/hypoxia-inducible factor-1α (HIF-1α)/vascular endothelial growth factor (VEGF) signaling axis. Bovine type II collagen-induced arthritis (CIA) mouse models and lipopolysaccharide (LPS)-stimulated EA.hy926 endothelial cells were utilized in this study. The effects of EMO on joint pathological alterations, the expression of NF-κB/HIF-1α/VEGF axis proteins, inflammatory cytokines (tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and interleukin-1 beta (IL-1β)), and angiogenic capacity were assessed using histopathological analysis, Western blotting, immunohistochemistry (IHC), immunofluorescence, and tube formation assays. Furthermore, small interfering RNA (siRNA) interference targeting key molecules was employed to validate the molecular mechanisms underlying the therapeutic effects of EMO. In the CIA model group, the ankle joints of mice exhibited pronounced inflammatory infiltration, synovial hyperplasia, and bone destruction. Compared with the model group, both the EMO and methotrexate (MTX) treatment groups demonstrated attenuated synovial hyperplasia and cartilage destruction, along with significantly downregulated expression levels of key NF-κB pathway proteins, HIF-1α, and VEGF in joint tissues (p < 0.001). In vitro experiments revealed that EMO treatment significantly reduced the LPS-induced secretion of pro-inflammatory cytokines (TNF-α, IL-6, and IL-1β) (p < 0.001), and decreased both the number and total length of tubular structures formed by endothelial cells compared to the control (p < 0.001). Notably, siRNA-mediated knockdown of p65 resulted in decreased intracellular protein levels of HIF-1α and VEGF, accompanied by a significant reduction in tube formation (p < 0.001). This study demonstrates that EMO alleviates pathological damage in RA by inhibiting the activation of the NF-κB signaling pathway, which subsequently downregulates pathological angiogenesis and inflammatory responses mediated by the HIF-1α/VEGF axis. These findings provide a robust experimental basis for the potential application of EMO as a therapeutic agent for RA. Full article

Microvascular leakage is an early hallmark of diabetic retinopathy (DR), but the redox-dependent mechanisms underlying this dysfunction remain unclear. Here, we investigated whether p38α mitogen-activated protein kinase (MAPK) activates transglutaminase 2 (TGase2) through reactive oxygen species (ROS) generation, thereby promoting hyperglycemia-induced vascular permeability in diabetic retinas. In human retinal endothelial cells (HRECs), vascular endothelial growth factor (VEGF), which is elevated under hyperglycemic conditions, activated both p38α MAPK and TGase2. VEGF-induced TGase2 activation was inhibited by the p38 MAPK inhibitor SB203580 or by p38α MAPK siRNA. Similarly, VEGF-stimulated TGase2 activity in non-diabetic mouse retinas was blocked by knockdown of either p38α MAPK or TGase2. In diabetic retinas, hyperglycemia-increased ROS production and TGase2 activity were reduced by SB203580 or p38α MAPK siRNA, but not by the TGase inhibitor cystamine, indicating upstream ROS-dependent regulation. The antioxidant Trolox also suppressed TGase2 activation in VEGF-treated HRECs and diabetic retinas. Functionally, knockdown of p38α MAPK or TGase2 preserved vascular endothelial (VE)-cadherin integrity and attenuated cytoskeletal remodeling in HRECs and diabetic retinas, resulting in reduced microvascular leakage. These findings identify a redox-dependent p38α MAPK–TGase2 axis as a key mediator of retinal vascular permeability in DR and highlight this pathway as a potential therapeutic target for maintaining vascular integrity. Full article

Uveal melanoma (UM) is the most prevalent primary intraocular tumor in adults. Transcription factor ZEB1 is one of the potential master regulators of melanocytes plasticity, because it is recognized as a “driver” of epithelial-to-mesenchymal transitions (EMTs) in carcinomas. We studied the correlation of tumor invasiveness with ZEB1 status and vascular endothelial growth factor/its receptor (VEGF-A/VEGFR2) in UM cells, and also with melanocyte’s differentiation rate. Eight UM cell cultures were characterized by melanosomes content using an ETM. ZEB1, VEGF-A and VEGFR2 levels in UM cells were detected by RT-PCR, Western blot, ELISA and flow cytometry. Effects of siRNA-dependent ZEB1 knockdown on UM cell proliferation and their sensitivity to the VEGF-A inhibitor Eylea (aflibercept) were tested by MTT and in a real-time proliferation assay. UMs with an invasive growth type can maintain a high degree of melanocyte differentiation. All ZEB1^low cells were obtained from spindle cell tumors. The sensitivity of UM cells to Eylea inversely correlated with the level of the VEGFR2 receptor. ZEB1 knockdown completely blocked VEGF-A production while anti-VEGF treatment stimulated ZEB1 increase. In UM cell cultures, ZEB1 is a positive regulator of VEGF-A expression. In addition, there is probably a ZEB1 feedback loop that is sensitive to a drop in VEGF-A concentration. The data obtained allow us to consider ZEB1 silencing as an auxiliary link for a combined strategy of killing UM cells. Full article

Background/Objectives: Glioblastoma (GBM) is an aggressive primary brain tumor with limited therapeutic options despite multimodal treatment. Small interfering RNA (siRNA)-based therapeutics can silence tumor-promoting genes, but achieving efficient and tumor-specific delivery remains challenging. Lipid nanoparticles (LNPs) are promising siRNA carriers; however, conventional antibody conjugation can impair antigen recognition and complicate manufacturing. This study aimed to establish a modular Fc-binding peptide (FcBP)-mediated post-insertion strategy to enable PD-L1-targeted delivery of VEGF-siRNA via LNPs for GBM therapy. Methods: Preformed VEGF-siRNA-loaded LNPs were functionalized with FcBP–lipid conjugates, enabling non-covalent anchoring of anti-PD-L1 antibodies through Fc interactions. Particle characteristics were analyzed using dynamic light scattering and encapsulation efficiency assays. Targeted cellular uptake and VEGF gene silencing were evaluated in PD-L1-positive GL261 glioma cells. Anti-tumor efficacy was assessed in a subcutaneous GL261 tumor model following repeated intratumoral administration using tumor volume and bioluminescence imaging as endpoints. Results: FcBP post-insertion preserved LNP particle size (125.2 ± 1.3 nm), polydispersity, zeta potential, and siRNA encapsulation efficiency. Anti-PD-L1–FcBP-LNPs significantly enhanced cellular uptake (by ~50-fold) and VEGF silencing in PD-L1-expressing GL261 cells compared to controls. In vivo, targeted LNPs reduced tumor volume by 65% and markedly suppressed bioluminescence signals without inducing weight loss. Final tumor weight was reduced by 63% in the anti-PD-L1–FcBP–LNP group (656.9 ± 125.4 mg) compared to the VEGF-siRNA LNP group (1794.1 ± 103.7 mg). The FcBP-modified LNPs maintained antibody orientation and binding activity, enabling rapid functionalization with targeting antibodies. Conclusions: The FcBP-mediated post-insertion strategy enables site-specific, modular antibody functionalization of LNPs without compromising physicochemical integrity or antibody recognition. PD-L1-targeted VEGF-siRNA delivery demonstrated potent, selective anti-tumor effects in GBM murine models. This platform offers a versatile approach for targeted nucleic acid therapeutics and holds translational potential for treating GBM. Full article

Neovascular ocular diseases are caused by vascular endothelial growth factor A (VEGFA) overexpression. Thus, VEGFA inhibition is considered the main strategy for treating ocular neovascularization. However, existing anti-VEGF therapies have several limitations in stability and delivery efficiency. To overcome the limitations, exosome-based VEGF siRNA delivery technology has attracted attention since exosomes have the advantages of high in vivo stability and excellent intracellular delivery efficiency. Additionally, loading VEGFA siRNA into exosomes not only allows for targeting specific cells or tissues but can also improve therapeutic efficacy. Our research team purified and concentrated exosomes using chromatography techniques, added fluorescein amidite (FAM)-labeled VEGFA siRNA into exosomes, and observed the novel effect of drug delivery in vitro. This study successfully introduced hVEGFA siRNA-FAM into target cells, with high efficacy particularly at 48 h after treatment. Furthermore, the enhanced inhibition of VEGFA expression at 48 h post-treatment was confirmed. FACS analysis was performed using the apoptosis markers Annexin V-FITC (green) and PI-PE (red) to confirm the presence or absence of apoptosis. Both groups treated with hVEGFA siRNA-FAM-EXO (1) and hVEGFA siRNA-FAM-EXO (2) showed increased apoptosis as the exposure time passed compared to the untreated group (0 h). hVEGFA siRNA-FAM-EXO treatment effectively induced apoptosis. After 24 h, early apoptosis was 12.9% and 13.9% and late apoptosis was 1.5% and 3.7% in hVEGFA siRNA-FAM-EXO groups (1) and (2), respectively. After 48 h, early apoptosis was 23.9% and late apoptosis was 39.4% and 17.8% in hVEGFA siRNA-FAM-EXO groups (1) and (2), respectively, indicating a time-dependent pattern of apoptosis progression. Additionally, tube formation of human vascular endothelial cells (HUVECs) was induced to confirm the effect of VEGFA siRNA-loaded exosomes on the angiogenesis assay in vitro. Compared with controls, angiogenesis became significantly weakened in hVEGFA siRNA-FAM-EXO (1)- and hVEGFA siRNA-FAM-EXO (2)-treated groups at 48 h post-treatment and completely disappeared at 72 h, probably occurring due to decreased VEGFA, PIGF, and VEGFC in the intracellular cytosol and conditioned media secreted by VEGFA siRNA-FAM in HUVECs. In conclusions, FAM-tagged VEGFA siRNA was packed into exosomes and degraded over time after tube formation, leading to cell death due to a decrease in VEGFA, PIGF, and VEGFC levels. This study is expected to support the development of in vivo neovascularization models (keratitis, conjunctivitis, or diabetic retinopathy models) in the future. Full article

Artesunate (AS) and tetramethylpyrazine (TMP) have been proven to have therapeutic potential in ischemic stroke. Nevertheless, their synergistic treatment mechanisms and effectiveness remain unclear. A rat MCAO model was induced, and AS, combined with TMP, was administered intranasally to rats once a day for 3 days. The neurological severity scores, TTC staining, and H&E staining were implemented to analyze tissue injuries. Evans blue staining and immunohistochemistry of ZO-1, occludin, MMP-9, and TIMP-1 were implemented to evaluate the integrity of the blood–brain barrier (BBB). ELISA was used to detect the expression levels of inflammatory factors TNF-α and IL-10. TUNEL staining and the protein expression of Bax and Bcl-2 were used to evaluate the apoptosis of brain tissue cells. The core targets were predicted by network pharmacology and verified by the OGD/R cell model and siRNA in vitro. Results showed that nasal administration of AS and TMP significantly ameliorated ischemic-stroke-induced neurological dysfunction, BBB disruption, and cortical neuronal apoptosis. The protective mechanisms mainly included adjusting the expression and ratio of tight junction proteins TIMP-1 and MMP-9 in brain tissue, regulating the HIF-1α-VEGF pathway, and anti-inflammatory effects. This study provides experimental support for the further development and application of AS and TMP nasal combinations and provides the foundation for expanding the practical-application value of artemisinin and its derivatives. Full article

Background/Objectives: HIF-1α and ERRα are both implicated in breast cancer progression, yet their functional interplay remains poorly understood. This study investigates their molecular crosstalk in the context of hypoxia-induced drug resistance. Methods: MCF-7 (estrogen receptor, ER-positive) spheroids and CoCl₂-treated SK-BR-3 (ER-negative) cells were used to model tumor hypoxia. Protein expression, coimmunoprecipitation, chromatin immunoprecipitation (ChIP), pharmacological inhibition, and siRNA-mediated gene silencing were employed to assess physical and functional interactions. Immunohistochemistry (IHC) on a tissue microarray (TMA) of 168 invasive breast carcinomas was performed to evaluate clinical relevance. Results: ERRα levels remained unchanged under hypoxia, while its coactivator, Peroxisome Proliferator-Activated Receptor Gamma Coactivator-1 α (PGC-1α), was upregulated. ERRα physically interacted with HIF-1α and was required for HIF-1 transcriptional activity under hypoxic conditions. ChIP assays showed that ERRα-driven overexpression of Permeability glycoprotein 1 (P-gp) and Vascular Endothelial Growth Factor (VEGF) was mediated by HIF-1α binding to the MDR1 and VEGF promoters. Inhibition or silencing of ERRα reversed P-gp overexpression and restored intracellular doxorubicin. TMA analysis confirmed the clinical correlation between ERRα, HIF-1α, and P-gp expression, highlighting the role of ERRα in hypoxia-induced drug resistance. ERRα expression was independent of ER status, suggesting an estrogen-independent function. Conclusions: This study identifies a novel physical and functional interaction between ERRα and HIF-1α that promotes chemoresistance in hypoxic breast tumors. Targeting ERRα may represent a promising therapeutic strategy to overcome drug resistance in aggressive, ER-independent breast cancer subtypes. Full article

Age-related macular degeneration (AMD) is a multifactorial retinal disease influenced by complex molecular mechanisms, including genetic susceptibility, inflammation, oxidative stress, and metabolic dysregulation. While substantial progress has been made in understanding its pathogenesis, the full molecular underpinnings of AMD remain unclear, impeding the effectiveness of current therapeutic strategies. This study provides an in-depth exploration of the molecular interactions involved in AMD progression, particularly focusing on genetic predispositions (such as CFH, ARMS2/HTRA1, and APOE), inflammatory pathways (including complement system dysregulation and cytokine responses), lipid metabolism (e.g., cholesterol homeostasis and drusen formation), and angiogenesis (VEGF signaling). Through a systematic review and bibliometric analysis of literature published between 2015 and 2025, the study identifies emerging research trends, existing gaps, and promising future therapeutic directions. It further investigates innovative precision medicine approaches, including gene editing (CRISPR), RNA therapeutics (siRNA, antisense oligonucleotides), immunomodulatory therapies, and nanotechnology-based drug delivery systems. Additionally, the study examines the role of metabolic disorders such as diabetes and dyslipidemia in AMD progression, highlighting the influence of systemic health factors on disease onset. Finally, the potential of artificial intelligence (AI) in enhancing AMD management through biomarker-based risk stratification, predictive modeling, and personalized treatment optimization is assessed. By mapping the intricate molecular networks underlying AMD and evaluating novel therapeutic strategies, this research aims to contribute to the development of more effective, individualized treatment protocols for patients with AMD. Full article

Growth differentiation factor 6 (GDF6), a member of the TGF-β superfamily, plays multifaceted roles in tumorigenesis, yet its molecular mechanisms and cancer-type-specific regulatory networks remain poorly defined. This study investigates GDF6’s context-dependent functions through pan-cancer multi-omics integration and functional validation. Transcriptomic data from TCGA (33 cancers, n = 10,535) and GTEx were analyzed to assess GDF6 dysregulation. Co-expression networks, pathway enrichment (KEGG/GO), and epigenetic interactions (m6A, m5C, m1A) were explored. Functional assays included siRNA knockdown, wound healing, and validation in immunotherapy cohorts. GDF6 exhibited bidirectional expression patterns, with downregulation in 23 cancers (e.g., GBM, BRCA) and upregulation in 7 malignancies (e.g., KIRC, PAAD). Mechanistically, GDF6 activated the PI3K-Akt/VEGF pathways, thereby promoting angiogenesis and metastasis. It modulated epigenetic regulation through interactions with m6A readers and erasers. Additionally, GDF6 reshaped the immune microenvironment by recruiting myeloid-derived suppressor cells (MDSCs) and cancer-associated fibroblasts. Notably, GDF6’s dual role extended to immunotherapy: it suppressed anti-PD1 efficacy but enhanced anti-PD-L1 sensitivity, linked to differential MHC-II and hypoxia-response regulation. This study deciphers GDF6’s context-dependent molecular networks, revealing its dual roles in metastasis and immune evasion. These findings highlight GDF6 as a central node in TGF-β-mediated oncogenic signaling and a potential therapeutic target for precision intervention. Full article

The integration of small interfering RNA (siRNA) with traditional cancer therapies represents a promising frontier in oncology aimed at enhancing treatment effectiveness, reducing side effects, and overcoming drug resistance. This review highlights the potential of siRNA to selectively silence genes that are overexpressed or uniquely expressed in cancer cells, thereby disrupting critical pathways that support tumor growth and survival. Key target genes discussed include survivin, VEGF, EGFR, c-MET, HER2, MUC1, and Bcl-2, all of which play vital roles in tumor proliferation, angiogenesis, and resistance to therapies. Clinical trials investigating various siRNA candidates, such as EZN-3042 and ALN-VSP, indicate that these therapies are generally well-tolerated; however, significant challenges persist, including the effective delivery and stability of siRNA. Recent advancements in nanoparticle-based delivery systems have shown promise in addressing these issues. Future research will focus on optimizing siRNA delivery methods, personalizing therapies based on individual genetic profiles, and establishing clearer regulatory guidelines for approval. As the field evolves, siRNA-based combination therapies are poised to become an integral part of precision oncology, offering new therapeutic options and hope for patients with difficult-to-treat cancers. Full article

Macrophages, pivotal components of the immune system, orchestrate host defense mechanisms in humans and mammals. Their polarization into classically activated macrophages (CAMs or M1) and alternatively activated macrophages (AAMs or M2) dictates distinct functional roles in immunity and tissue homeostasis. While the negative regulatory role of CD32b within the FC gamma receptor (FCγR) family is recognized across various immune cell types, its influence on macrophage polarization remains elusive. This study aimed to elucidate the regulatory role of CD32b in macrophage polarization and discern the differential expression markers between the M1 and M2 phenotypes following CD32b siRNA transfection. The results revealed a decrease in the CD32b levels in lipopolysaccharide (LPS)-treated M1 and an increase in interleukin-4 (IL-4)-treated M2 macrophages, as observed in macrophage Raw264.7 cells. Furthermore, CD32b siRNA transfection significantly downregulated the M2 markers (IL-10, VEGF, Arg-1, and STAT6), while upregulating the M1 markers (IL-6, NF-κB, NOS2, and STAT1) in the Raw264.7 cells. Similar findings were recapitulated in macrophage-rich adherent cells isolated from mouse spleens. Additionally, the cytopathological analysis of pleural effusions and ascitic fluids from patients with cancer revealed a positive correlation between advanced tumor stages, metastasis, and elevated CD32b levels. In conclusion, this study highlights the regulatory influence of CD32b in suppressing M1 expression and promoting M2 polarization. Moreover, heightened M2 activation and CD32b levels appear to correlate with tumor progression. A targeted CD32b blockade may serve as a novel therapeutic strategy to inhibit M2 macrophage polarization and is promising for anti-tumor intervention. Full article

Non-healing lesions in diabetic foot ulcers are a significant effect of poor angiogenesis. Epigenetic regulators, mainly lncRNA and miRNA, are recognized for their important roles in disease progression. We deciphered the regulation of lncRNA NEAT1 through the miR-146a-5p/mafG axis in the progression of DFU. A lowered expression of lncRNA NEAT1 was associated with dysregulated angiogenesis through the reduced expression of mafG, SDF-1α, and VEGF in chronic ulcer subjects compared to acute DFU. This was validated by silencing NEAT1 by SiRNA in the endothelial cells which resulted in the transcriptional repression of target genes. Our in silico analysis identified miR-146a-5p as a potential target of lncRNA NEAT1. Further, silencing NEAT1 led to an increase in the levels of miR-146a-5p in chronic DFU subjects. This research presents the role of the lncRNA NEAT1/miR-146a-5p/mafG axis in enhancing angiogenesis in DFU. Full article

Endometriosis (EM) is a prevalent gynecological disease characterized by the abnormal growth of tissue similar to the endometrium outside of the uterus. This condition is accompanied by the development of new blood vessels in endometriotic lesions. While surgical intervention is effective in removing endometriotic lesions, some patients require multiple surgeries. Therefore, finding non-surgical treatments for EM is of great interest. One of the promising approaches is anti-angiogenic therapy using siRNA-therapeutics to target the expression of the VEGFA gene. Peptide-based polymers have shown promise as siRNA delivery systems due to their biocompatibility and ease of modification. We conducted a study to evaluate the effectiveness of the R6p-cRGD peptide carrier as a non-viral vehicle for delivering siRNA to endothelial cells in vitro and endometrial implants in vivo. We investigated the physicochemical properties of the siRNA-complexes, assessed cellular toxicity, and examined the efficiency of GFP and VEGFA genes silencing. Furthermore, we tested the anti-angiogenic effects of these complexes in cellular and animal models. The transfection with siRNA complexes led to a significant increase in VEGFA gene knockdown efficiency and a decrease in the migration of endothelial cells. For the animal model, we induced endometriosis in rats by transplanting endometrial tissue subcutaneously. We evaluated the efficiency of anti-angiogenic therapy for EM in vivo using anti-VEGF siRNA/R6p-RGD complexes. During this assessment, we measured the volume of the implants, analyzed VEGFA gene expression, and conducted CD34 immunohistochemical staining. The results showed a significant decrease in the growth of endometriotic implants and in VEGFA gene expression. Overall, our findings demonstrate the potential of the R6p-cRGD peptide carrier as a delivery system for anti-angiogenic therapy of EM. Full article

Antiangiogenic therapy with sorafenib (SF) alone is ineffective in eradicating tumors, and its long-term application can exacerbate tumor hypoxia, which in turn restricts SF’s therapeutic efficacy. Here, a redox-responsive fluorinated peptide (DEN-TAT-PFC) consisting of dendritic poly-lysine, cell-penetrating peptide TAT, and perfluorocarbon was designed and synthesized to co-load siRNA-targeting hypoxia-inducible factors (siHIF-1α) and SF. The unique architecture of the peptide and fluorinated modifications enhanced the siRNA delivery efficiency, including increased siRNA binding, GSH-responsive release, cellular uptake, endosomal escape, and serum resistance. Simultaneously, the DEN-TAT-PFC/SF/siHIF-1α co-delivery system achieved efficient knockdown of HIF-1α at mRNA and protein levels, thus alleviating hypoxia and further substantially reducing VEGF expression. Additionally, the excellent oxygen-carrying ability of DEN-TAT-PFC may facilitate relief of the hypoxic microenvironment. As a result of these synergistic effects, DEN-TAT-PFC/SF/siHIF-1α exhibited considerable anti-tumor cell proliferation and anti-angiogenesis effects. Therefore, DEN-TAT-PFC can be a versatile platform for fabricating fluorine-containing drugs/siRNA complex nano-systems. Full article

Previous studies have revealed that norrin can reverse vascular endothelial-growth-factor (VEGF)-induced permeability in a β-catenin-dependent pathway. Here, we have explored the contribution of disheveled-1 (DVL1) in norrin-induced blood-retinal barrier (BRB) restoration. We provide evidence that in addition to canonical signaling, DVL1 promotes tight junction (TJ) stabilization through a novel, non-canonical signaling pathway involving direct claudin-5 (CLDN5) binding. Immunofluorescence staining of rat retinal cross-sections showed enriched expression of DVL1 and 3 at endothelial capillaries and co-localization with CLDN5 and ZO-1 at the TJ complex in primary bovine retinal endothelial cells (BRECs). Barrier properties of BRECs were determined via measurements of trans-endothelial electrical resistance (TEER) or permeability to 70 kDa RITC-dextran. These studies demonstrated that norrin restoration of barrier properties after VEGF treatment required DVL1 as an siRNA knockdown of Dvl1 but not Dvl2 or Dvl3, reduced basal barrier properties and ablated norrin-induced barrier restoration. However, loss of Dvl1 did not decrease β-catenin signaling activity as measured by Axin2 mRNA expression, suggesting the contribution of a non-canonical pathway. DVL and TJ protein interactions were analyzed via co-immunoprecipitation of endogenous protein in BRECs, which demonstrated that DVL1 interacts with both CLDN5 and ZO-1, while DVL3 interacts only with ZO-1. These interactions were most abundant after inducing BRB restoration by treating BRECs with VEGF and norrin. DVL has previously been shown to form intramolecular bindings between the C-terminal PDZ-binding motif (PDZ-BM) with an internal PDZ domain. Co-transfection of HEK293 cells with DVL1 and CLDN5 or relevant mutants revealed that DVL1 interacts with CLDN5 through the DVL PDZ domain binding, CLDN5 PDZ-BM, in competition with DVL1 PDZ-BM, since DVL/CLDN5 interaction increases with deletion of the DVL1 PDZ-BM and decreases by co-expressing the C-terminal fragment of DVL1 containing the PDZ-BM or through deletion of CLDN5 PDZ-BM. In BREC cells, transfection of the C-terminal fragment of DVL1 downregulates the expression of CLDN5 but does not affect the expression of other proteins of the TJs, including ZO-1, occludin, CLDN1 or VE-cadherin. Blocking DVL1/CLDN5 interaction increased basal permeability and prevented norrin induction of barrier properties after VEGF. Combined with previous data, these results demonstrate that norrin signals through both a canonical β-catenin pathway and a non-canonical signaling pathway by which DVL1 directly binds to CLDN5 to promote barrier properties. Full article