Phosphorylated cingulin localises GEF-H1 at tight junctions to protect vascular barriers in blood endothelial cells

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.

Cingulin family: Structure, function and clinical significance

Cingulin and its paralog paracingulin are vital components of the apical junctional complex in vertebrate epithelial and endothelial cells. They are both found in tight junctions (TJ), and paracingulin is also detectable in adherens junctions (AJ) as TJ cytoplasmic plaque proteins. Cingulin and paracingulin interact with other proteins to perform functions. They interact with cytoskeletal proteins, modulate the activity of small GTPases, such as RhoA and Rac1, and regulate gene expression. In addition, cingulin and paracingulin regulate barrier function and many pathological processes, including inflammation and tumorigenesis. In this review, we summarize the discovery and structure, expression and subcellular distribution, and molecular interactions of cingulin family proteins and discuss their role in development, physiology, and pathological processes.

Blockage of VEGF function by bevacizumab alleviates early-stage cerebrovascular dysfunction and improves cognitive function in a mouse model of Alzheimer's disease

BACKGROUND

Alzheimer's disease (AD) is a neurodegenerative disorder and the predominant type of dementia worldwide. It is characterized by the progressive and irreversible decline of cognitive functions. In addition to the pathological beta-amyloid (Aβ) deposition, glial activation, and neuronal injury in the postmortem brains of AD patients, increasing evidence suggests that the often overlooked vascular dysfunction is an important early event in AD pathophysiology. Vascular endothelial growth factor (VEGF) plays a critical role in regulating physiological functions and pathological changes in blood vessels, but whether VEGF is involved in the early stage of vascular pathology in AD remains unclear.

METHODS

We used an antiangiogenic agent for clinical cancer treatment, the humanized monoclonal anti-VEGF antibody bevacizumab, to block VEGF binding to its receptors in the 5×FAD mouse model at an early age. After treatment, memory performance was evaluated by a novel object recognition test, and cerebral vascular permeability and perfusion were examined by an Evans blue assay and blood flow scanning imaging analysis. Immunofluorescence staining was used to measure glial activation and Aβ deposits. VEGF and its receptors were analyzed by enzyme-linked immunosorbent assay and immunoblotting. RNA sequencing was performed to elucidate bevacizumab-associated transcriptional signatures in the hippocampus of 5×FAD mice.

RESULTS

Bevacizumab treatment administered from 4 months of age dramatically improved cerebrovascular functions, reduced glial activation, and restored long-term memory in both sexes of 5×FAD mice. Notably, a sex-specific change in different VEGF receptors was identified in the cortex and hippocampus of 5×FAD mice. Soluble VEGFR1 was decreased in female mice, while full-length VEGFR2 was increased in male mice. Bevacizumab treatment reversed the altered expression of receptors to be comparable to the level in the wild-type mice. Gene Set Enrichment Analysis of transcriptomic changes revealed that bevacizumab effectively reversed the changes in the gene sets associated with blood-brain barrier integrity and vascular smooth muscle contraction in 5×FAD mice.

CONCLUSIONS

Our study demonstrated the mechanistic roles of VEGF at the early stage of amyloidopathy and the protective effects of bevacizumab on cerebrovascular function and memory performance in 5×FAD mice. These findings also suggest the therapeutic potential of bevacizumab for the early intervention of AD.

Knock Out of CGN and CGNL1 in MDCK Cells Affects Claudin-2 but Has a Minor Impact on Tight Junction Barrier Function

Cingulin (CGN) and paracingulin (CGNL1) are cytoplasmic proteins of tight junctions (TJs), where they play a role in tethering ZO-1 to the actomyosin and microtubule cytoskeletons. The role of CGN and CGNL1 in the barrier function of epithelia is not completely understood. Here, we analyzed the effect of the knock out (KO) of either CGN or CGNL1 or both on the paracellular permeability of monolayers of kidney epithelial (MDCK) cells. KO cells displayed a modest but significant increase in the transepithelial resistance (TER) of monolayers both in the steady state and during junction assembly by the calcium switch, whereas the permeability of the monolayers to 3 kDa dextran was not affected. The permeability to sodium was slightly but significantly decreased in KO cells. This phenotype correlated with slightly increased mRNA levels of claudin-2, slightly decreased protein levels of claudin-2, and reduced junctional accumulation of claudin-2, which was rescued by CGN or CGNL1 but not by ZO-1 overexpression. These results confirm previous observations indicating that CGN and CGNL1 are dispensable for the barrier function of epithelia and suggest that the increase in the TER in clonal lines of MDCK cells KO for CGN, CGNL1, or both is due to reduced protein expression and junctional accumulation of the sodium pore-forming claudin, claudin-2.

Paracrine Factors of Stressed Peripheral Blood Mononuclear Cells Activate Proangiogenic and Anti-Proteolytic Processes in Whole Blood Cells and Protect the Endothelial Barrier

Tissue-regenerative properties have been attributed to secreted paracrine factors derived from stem cells and other cell types. In particular, the secretome of γ-irradiated peripheral blood mononuclear cells (PBMCsec) has been shown to possess high tissue-regenerative and proangiogenic capacities in a variety of preclinical studies. In light of future therapeutic intravenous applications of PBMCsec, we investigated the possible effects of PBMCsec on white blood cells and endothelial cells lining the vasculature. To identify changes in the transcriptional profile, whole blood was drawn from healthy individuals and stimulated with PBMCsec for 8 h ex vivo before further processing for single-cell RNA sequencing. PBMCsec significantly altered the gene signature of granulocytes (17 genes), T-cells (45 genes), B-cells (72 genes), and, most prominently, monocytes (322 genes). We detected a strong upregulation of several tissue-regenerative and proangiogenic cyto- and chemokines in monocytes, including VEGFA, CXCL1, and CXCL5. Intriguingly, inhibitors of endopeptidase activity, such as SERPINB2, were also strongly induced. Measurement of the trans-endothelial electrical resistance of primary human microvascular endothelial cells revealed a strong barrier-protective effect of PBMCsec after barrier disruption. Together, we show that PBMCsec induces angiogenic and proteolytic processes in the blood and is able to attenuate endothelial barrier damage. These regenerative properties suggest that systemic application of PBMCsec might be a promising novel strategy to restore damaged organs.

Rho and Rab Family Small GTPases in the Regulation of Membrane Polarity in Epithelial Cells

Membrane polarity, defined as the asymmetric distribution of lipids and proteins in the plasma membrane, is a critical prerequisite for the development of multicellular tissues, such as epithelia and endothelia. Membrane polarity is regulated by polarized trafficking of membrane components to specific membrane domains and requires the presence of intramembrane diffusion barriers that prevent the intermixing of asymmetrically distributed membrane components. This intramembrane diffusion barrier is localized at the tight junctions (TJs) in these cells. Both the formation of cell-cell junctions and the polarized traffic of membrane proteins and lipids are regulated by Rho and Rab family small GTPases. In this review article, we will summarize the recent developments in the regulation of apico-basal membrane polarity by polarized membrane traffic and the formation of the intramembrane diffusion barrier in epithelial cells with a particular focus on the role of Rho and Rab family small GTPases.

More than Just a Monolayer: the Multifaceted Role of Endothelial Cells in the Pathophysiology of Atherosclerosis

Purpose of the Review

In this review, we summarize current insights into the versatile roles of endothelial cells in atherogenesis.

Recent Findings

The vascular endothelium represents the first barrier that prevents the entry of lipoproteins and leukocytes into the vessel wall, thereby controlling two key events in the pathogenesis of atherosclerosis. Disturbance of endothelial homeostasis increases vascular permeability, inflammation, and cellular trans-differentiation, which not only promotes the build-up of atherosclerotic plaques but is also involved in life-threatening thromboembolic complications such as plaque rupture and erosion. In this review, we focus on recent findings on endothelial lipoprotein transport, inflammation, cellular transitions, and barrier function.

Summary

By using cutting-edge technologies such as single-cell sequencing, epigenetics, and cell fate mapping, novel regulatory mechanisms and endothelial cell phenotypes have been discovered, which have not only challenged established concepts of endothelial activation, but have also led to a different view of the disease.