NRF2-HIF2α Signaling Attenuates Endothelial Cell Senescence and Maintains Intercellular Junctions in Diabetes.

In the context of diabetes, endothelial cells frequently exhibit compromised intercellular junctions and accelerated cellular senescence simultaneously. The precise mechanisms underlying these issues and the identification of effective treatments remain largely undefined. Our findings reveal that human umbilical vein endothelial cells (HUVECs) can counteract senescence and uphold the integrity of intercellular junctions under mildly to moderately elevated glucose levels (10 mM and 15 mM) via two primary mechanisms: i) The acetylation of NRF2 at lysine residues K56, K68, and K52 prevents its ubiquitination, enhancing the transcription of antioxidant genes GST, SOD1, and GPX1. This activity diminishes cytoplasmic oxidative stress, thereby mitigating endothelial cell senescence. ii) The interaction between the Neh2 domain of NRF2 and the PAS-B domain of HIF-2α within the nucleus curtails the attachment of HIF-2α to the NOX4/p22phox promoter. This action lessens oxidative stress near the cell membrane, maintaining intercellular junctions by safeguarding the disulfide bonds in occludin and E-cadherin from disruption. However, these protective strategies prove insufficient under severe hyperglycemic conditions (25 mM). Further investigation has identified Oltipraz, an activator of NRF2, as also promoting the degradation of HIF-2α. Through its simultaneous modulation of NRF2 and HIF-2α, Oltipraz significantly reduces cellular senescence and prevents the deterioration of intercellular junctions in HUVECs subjected to high glucose concentrations (25 mM). Our research positions Oltipraz as a promising therapeutic candidate for mitigating diabetes-induced vascular endothelial damage, potentially offering benefits against diabetes-related atherosclerosis and valvular calcification.

Desmosomes at a glance.

Desmosomes are relatives of ancient cadherin-based junctions, which emerged late in evolution to ensure the structural integrity of vertebrate tissues by coupling the intermediate filament cytoskeleton to cell-cell junctions. Their ability to dynamically counter the contractile forces generated by actin-associated adherens junctions is particularly important in tissues under high mechanical stress, such as the skin and heart. Much more than the simple cellular 'spot welds' depicted in textbooks, desmosomes are in fact dynamic structures that can sense and respond to changes in their mechanical environment and external stressors like ultraviolet light and pathogens. These environmental signals are transmitted intracellularly via desmosome-dependent mechanochemical pathways that drive the physiological processes of morphogenesis and differentiation. This Cell Science at a Glance article and the accompanying poster review desmosome structure and assembly, highlight recent insights into how desmosomes integrate chemical and mechanical signaling in the epidermis, and discuss desmosomes as targets in human disease.

The mechanism of selenium regulating the permeability of vascular endothelial cells through selenoprotein O.

Vascular diseases, a leading cause of death in human, are strongly associated with pathological damage to blood vessels. The selenoprotein (Sel) have been reported to play important roles in vascular disease. However, the role of SelO in vascular disease has not been conclusively investigated. The present experiment was to investigate the regulatory mechanism of the effect of SelO on the permeability of vascular endothelial. The H.E staining, FITC-Dextran staining, Dil-AC-LDL staining and FITC-WGA staining showed that vascular structure was damaged, and intercellular junctions were disrupted with selenium (Se)-deficient. Immunohistochemistry, qPCR and Western blot revealed decreased expression of the adhesion plaque proteins vinculin, talin and paxillin, decreased expression of the vascular connectivity effector molecules connexin, claudin-1 and E-cadherin and increased expression of JAM-A and N-cadherin, as well as decreased expression of the ZO-1 signaling pathways ZO-1, Rock, rhoGEF, cingulin and MLC-2. In a screening of 24 Sel present in mice, SelO showed the most pronounced changes in vascular tissues, and a possible association between SelO and vascular intercellular junction effectors was determined using IBM SPSS Statistics 25. Silencing of SelO, vascular endothelial intercellular junction adverse effects present. The regulatory relationship between SelO and vascular endothelial intercellular junctions was determined. The results showed that Se deficiency lead to increased vascular endothelial permeability and vascular tissue damage by decreasing SelO expression, suggesting a possible role for SelO in regulating vascular endothelial permeability.

DPP-4 exacerbates LPS-induced endothelial cells inflammation via integrin-α5ß1/FAK/AKT signaling.

Endothelial dysfunction plays a pivotal role in the pathogenesis of acute lung injury (ALI)/acute respiratory distress syndrome (ARDS). Dipeptidyl peptidase IV (DPP-4), a cell surface glycoprotein, has been implicated in endothelial inflammation and barrier dysfunction. In this study, the role of DPP-4 on lipopolysaccharide (LPS)-induced pulmonary microvascular endothelial cells (HPMECs) dysfunction and the underlying mechanism were investigated by siRNA-mediated knockdown of DPP-4. Our results indicated that LPS (1 µg/ml) challenge resulted in either the production and releasing of DPP-4, as well as the secretion of IL-6 and IL-8 in HPMECs. DPP-4 knockdown inhibited chemokine releasing and monolayer hyper-permeability in LPS challenged HPMECs. When cocultured with human polymorphonuclear neutrophils (PMNs), DPP4 knockdown suppressed LPS-induced neutrophil-endothelial adhesion, PMN chemotaxis and trans-endothelial migration. Western blotting showed that DPP-4 knockdown attenuated LPS-induced activation of TLR4/NF-κB pathway. Immunoprecipitation and liquid chromatography-tandem mass spectrometry revealed that DPP-4 mediated LPS-induced endothelial inflammation by interacting with integrin-α5ß1. Moreover, exogenous soluble DPP-4 treatment sufficiently activated integrin-α5ß1 downstream FAK/AKT/NF-κB signaling, thereafter inducing ICAM-1 upregulation in HPMECs. Collectively, our results suggest that endothelia synthesis and release DPP-4 under the stress of endotoxin, which interact with integrin-α5ß1 complex in an autocrine or paracrine manner to exacerbate endothelial inflammation and enhance endothelial cell permeability. Therefore, blocking DDP-4 could be a potential therapeutic strategy to prevent endothelial dysfunction in ALI/ARDS.

Overview of the compromised mucosal integrity in celiac disease.

Intestinal epithelium is a dynamic cellular layer that lines the small-bowel and makes a relatively impenetrable barrier to macromolecules. Intestinal epithelial cell polarity is crucial in coordinating signalling pathways within cells and mainly regulated by three conserved polarity protein complexes, the Crumbs (Crb) complex, partitioning defective (PAR) complex, and Scribble (Scrib) complex. Polarity proteins regulate the proper establishment of the intercellular junctional complexes including tight junctions (TJs), adherence junctions (AJs), and desmosomes which hold epithelial cells together and play a major role in maintaining intestinal barrier integrity. Impaired intestinal epithelial cell polarity and barrier integrity result in irreversible immune responses, the host- microbial imbalance and intestinal inflammatory disorders. Disassembling the epithelial tight junction and augmented paracellular permeability is a conspicuous hallmark of celiac disease (CD) pathogenesis. There are several dietary components that can improve intestinal integrity and function. The aim of this review article is to summarize current information about the association of polarity proteins and AJC damages with pathogenesis of CD.

Differential infection behavior of African swine fever virus (ASFV) genotype I and II in the upper respiratory tract.

African swine fever virus (ASFV) is a substantial threat to pig populations worldwide, contributing to economic disruption and food security challenges. Its spread is attributed to the oronasal transmission route, particularly in animals with acute ASF. Our study addresses the understudied role of nasal mucosa in ASFV infection, using a nasal explant model. The explants remained viable and revealed a discernible ASFV infection in nasal septum and turbinates post-inoculation. Interestingly, more infected cells were found in the turbinates despite its thinner structure. Further analyses showed (i) a higher replication of genotype II strain BEL18 than genotype I strain E70 in the epithelial cell layer, (ii) a preference of ASFV infection for the lamina propria and a tropism of ASFV for various susceptible cell types in different areas in the nasal mucosa, including epithelial cells, macrophages, and endothelial cells. Using porcine respiratory epithelial cells (PoRECs), isolated from nasal tissue, we found a difference in infection mechanism between the two genotypes, with genotype I favoring the basolateral surface and genotype II preferring the apical surface. Moreover, disruption of intercellular junctions enhanced infection for genotype I. This study demonstrated that ASFV may use the respiratory mucosa for entry using different cell types for replication with a genotype difference in their infection of respiratory epithelial cells.

Desmoglein-2 as a cancer modulator: friend or foe?

Desmoglein-2 (DSG2) is a calcium-binding single pass transmembrane glycoprotein and a member of the large cadherin family. Until recently, DSG2 was thought to only function as a cell adhesion protein embedded within desmosome junctions designed to enable cells to better tolerate mechanical stress. However, additional roles for DSG2 outside of desmosomes are continuing to emerge, particularly in cancer. Herein, we review the current literature on DSG2 in cancer and detail its impact on biological functions such as cell adhesion, proliferation, migration, invasion, intracellular signaling, extracellular vesicle release and vasculogenic mimicry. An increased understanding of the diverse repertoire of the biological functions of DSG2 holds promise to exploit this cell surface protein as a potential prognostic biomarker and/or target for better patient outcomes. This review explores the canonical and non-canonical functions of DSG2, as well as the context-dependent impacts of DSG2 in the realm of cancer.

New insights into the integrity of intercellular junctions between retinal pigment epithelial cells / 中华实验眼科杂志

Retinal pigment epithelium (RPE) is composed of a layer of highly specialized hexagonal pigment epithelial cells.The apical surface of RPE interacts with the photoreceptor, and RPE basal surface interacts with Bruch membrane and choroidal capillaries to maintain the function of retinal photoreceptor.A variety of junction proteins distributed between RPE cells are the basis for RPE to perform normal functions, ensuring the integrity and physiological function of RPE.Under pathological conditions, the abnormal function of RPE is first manifested by the abnormal junctional protein, which leads to the loss of adhesion between cells, cells and basement membrane, and then a series of abnormal biological behaviors, such as dissociation, migration, transdifferentiation and protein expression changes in RPE cells, which have become an important cause of many fundus diseases.The role of RPE junctional complexes during normal and pathological conditions, as well as their role in proliferative vitreoretinopathy, age-related macular degeneration and diabetic vitreoretinopathy was reviewed in this article from the composition and correlation of junctional proteins between RPE cells.

Importância das comunicações intercelulares para o desenvolvimento de folículos ovarianos / Intercellular communications in ovarian follicles

Durante a foliculogênese em mamíferos, ocorre um longo e complexo processo no qual o oócito adquire a competência necessária para a fecundação. Nesse processo ocorre uma comunicação metabólica bidirecional entre os oócitos e as células somáticas dentro do folículo que garante substratos para o oócito em desenvolvimento. Essa comunicação é mediada pelas junções celulares (junções comunicantes e junções aderentes) presentes nas projeções transzonais. As junções celulares e moléculas de adesão são responsáveis principalmente por promover a adesão entre as células foliculares; mas podem atuar em vias de sinalização celular e na regulação da transcrição gênica nas células somáticas e oócitos. Além disso, as junções comunicantes (junções gap) são canais intermembranares que intermediam a comunicação entre essas células através da passagem de pequenas moléculas. Essas junções comunicantes são compostas por proteínas denominadas conexinas; as conexinas 37 e 43 são as predominantes nos folículos ovarianos. Dessa forma, o conhecimento acerca das junções celulares é de extrema importância para o estudo da foliculogênese. A presente revisão teve como objetivo abordar os principais tipos de junções celulares existentes entre as células foliculares, com destaque para as junções gap e as principais proteínas de membranas (conexinas) presentes nos diferentes estágios do desenvolvimento folicular.

During the mammalian folliculogenesis, a long and complex process occurs, which the oocyte acquires the necessary competence for fecundation. In this process there is a metabolic bidirectional communication among the oocyte and somatic cells inside the follicle, which provides substrates for the oocyte developmental competence. This communication is mediated by cellular junctions (occlusions, adherens and gap junctions) localized in the transzonal projections. Cellular junctions and adhesion mollecules are responsable mainly for promoving the adhesion among follicular cells, however they can act in cellular signaling pathways and in regulation of genic transcription in the follicular cells and oocyte. Moreover, the communication junctions (gap junctions) are intermembrane channels that intermediate the communication among these cells through the passage of small molecules. These gap junctions are composed by connexins, of which the connexins 37 and 43 are the most frequently found in the ovarian follicle. Thus, knowledge of these cellular junctions are of great importance for studying the folliculogenesis process. The aim of this review was to report the main types of cellular junctions localized among the follicular cells, especially the gap junctions and the main membrane proteins (connexins) found in different stages of the follicular development.

Uterine expression of tight junctions in the Canine uterus / 동물의과학연구지

Tight junctions (TJs) form continuous intercellular contacts in intercellular junctions. TJs involve integral proteins such as occludin (OCLN) and claudins (CLDNs) as well as peripheral proteins such as zona occludens-1 (ZO-1) and junctional adhesion molecules (JAMs). TJs control paracellular transportation across cell-to-cell junctions. Although TJs have been studied for several decades, comparison of the transcriptional-translational levels of these molecules in canine organs has not yet been performed. In this study, we examined uterine expression of CLDNs, OCLN, junction adhesion molecule-A, and ZO-1 in canine. Expression levels of canine uterine TJ proteins, including CLDN1, 2, 4, 5, JAM-A, ZO-1, and OCLN, were measured using reverse transcription PCR, real-time PCR, and Western blotting, whereas TJs distribution was determined by immunohistochemistry. The mRNA and protein expression levels of OCLN, CLDN-1, 4, JAM-1, and ZO-1 were identified in the uterus. Immunohistochemistry demonstrated that TJs were localized to the endometrium and/or myometrium of the uterus. Our results show that canine TJ proteins, including CLDNs, OCLN, JAM-A, and ZO-1, were expressed in the canine uterus. Taken together, these proteins may perform unique physiological roles in the uterus. Therefore, these findings may serve as a basis for further studies on TJ proteins and their roles in the physiological or pathological condition of the canine uterus.

Progress in promoting mechanism of tunneling nanotubes formation / 第二军医大学学报

Tunneling nanotubes (TNT) is a newly discovered connection mode between animal cells, and its formation is of great importance in physiological and pathological processes of animals and humans. The forming conditions and the promoting mechanism of TNT are not fully understood yet. It has been known that the state of cells (such as inflammatory conditions and stress reaction), molecular level (Fas ligand, cell adhesion molecules and the ligand interactions, M-Sec/TNFaip2/B94 and lipid molecules), and pathogenic infection are important for the formation of TNT. In this paper we reviewed the promoting mechanisms for TNT formation.

Interações em processos fisiológicos: a importância da dinâmica entre matriz extracelular e proteoglicanos: [revisão] / Interactions in physiological processes: the importance of the dynamics between extracellular matrix and proteoglycans: [review]

A matriz extracelular foi considerada por muito tempo uma estrutura inerte constituída por várias proteínas e polissacarídeos sintetizados e secretados pelas células para o preenchimento do espaço extracelular. Atualmente sabe-se que, além de auxiliar na ligação das células para a formação dos tecidos, a matriz extracelular tem papel importante no controle do crescimento e na diferenciação celular e, nessa interação, moléculas como proteoglicanos, glicosaminoglicanos, proteases e glicosidases desencadeam eventos de sinalização celular. Os proteoglicanos presentes na matriz extracelular realizam importantes funções, dentre elas, regulação da atividade de moléculas sinalizadoras, controle do tráfego de células e moléculas, atuação como coreceptorese interação com proteínas fibrosas da matriz. Esta revisão tem enfoque nas características estruturais da matriz extracelular, de proteoglicanose do papel fundamental das interações celulares.

The extracellular matrix was considered for a long time as an inert structure consisting of various proteins and polysaccharides synthesized and secreted by cells to fill the extracellular space. Currently it is known that, in addition to helping cells connection for the tissue formation, theextracellular matrix has an important role in the growth control and in the cellular differentiation, and in this interaction, some molecules like theproteoglycans, glycosaminoglycans, proteases, and glycosidases may trigger cellular signaling events. Proteoglycans present in the extracellularmatrix perform important functions, such as: control of signaling molecules, the transit control of cells and molecules, co-receptors action and interaction with matrix fibrous proteins. This review is focused on the structural characteristics of extracellular matrix, of proteoglycans and of the fundamental role of cellular interactions.