Coordination between Cell Motility and Cell Cycle Progression in Keratinocyte Sheets via Cell-Cell Adhesion and Rac1

Proteomic signatures of retinal pigment epithelium-derived exosomes in myopic and non-myopic tree shrew eyes

Purpose

The retinal pigment epithelium (RPE) transmits growth signals from the neural retina to the choroid in the emmetropization pathway, but the underlying molecular mechanisms remain poorly understood. Here, we compared the proteomic profiles of RPE-derived exosomes between myopic and non-myopic eyes of tree shrews, dichromatic mammals closely related to primates.

Methods

Four myopic (159-210 days of visual experience, DVE) and seven non-myopic eyes (156-210 DVE) of tree shrews were included. Non-cycloplegic refractive error was measured with Nidek autorefractor, and axial ocular component dimensions were recorded with LenStar. Tissue was collected, yielding RPE-lined eyecups, which were subsequently incubated in L-15 culture media for 2 h. The RPE-derived exosomes were then enriched and purified from the incubation media by double ultracentrifugation and characterized by imaging and molecular methods. Exosomal proteins were identified and quantified with mass spectrometry, examined using GO and KEGG analyses, and compared between myopic and non-myopic samples.

Results

Out of 506 RPE exosomal proteins identified, 48 and 41 were unique to the myopic and non-myopic samples, respectively. There were 286 differentially expressed proteins in the myopic samples, including 79 upregulated and 70 downregulated. The top three upregulated proteins were Histone H4 (Fold Change, FC = 3.04, p = 0.09), PTB 1 (FC = 2.59, p = 0.08) and Histone H3.1 (FC = 2.59, p = 0.13), while the top three downregulated proteins were RPS5 (FC = -2.41, p=0.004), ACOT7 (FC=-2.15, p = 0.04) and CRYBB2 (FC = -2.14, p = 0.05). Other differentially expressed proteins included LUM, VCL, SEPTIN11, GPX3, SPTBN1, SEPTIN7, RPL10A, KCTD12, FGG, and FMOD. Proteomic analysis revealed a low abundance of ATP6V1B2 and crystallin beta B2, and a significant depletion of the crystallin protein family (crystallin A2, A3, and B3 subunits) in the myopic samples. The enrichment analyses showed extracellular matrix, cytoskeletal dynamic, and cell-matrix adhesion as the primary components associated with the RPE exosomal proteins in myopic eyes.

Conclusion

Using standard molecular and imaging techniques, this study provides the first demonstration of the ex-vivo RPE exosome biogenesis from tree shrew eyes. The results showed distinct differential expressions of the RPE exosomal proteins between the myopic and non-myopic eyes, with several proteins unique to each group. Future targeted proteomic studies of identified candidate exosomal protein signatures could elucidate the molecular mechanism of RPE exosome-mediated growth signal transmission in the emmetropization pathway.

ARHGAP25: a novel player in the Pathomechanism of allergic contact hypersensitivity

Objective

Contact hypersensitivity (CHS), or allergic contact dermatitis (ACD), is an inflammatory skin disorder characterized by an exaggerated allergic reaction to specific haptens. During this delayed-type allergic reaction, the first contact with the allergen initiates the sensitization phase, forming memory T cells. Upon repeated contact with the hapten, the elicitation phase develops, activating mostly macrophages, cytotoxic T cells, and neutrophilic granulocytes. Our group previously demonstrated that the leukocyte-specific GTPase-activating protein ARHGAP25 regulates phagocyte effector functions and is crucial in the pathomechanism of autoantibody-induced arthritis. Here, we investigate its role in the pathogenesis of the more complex inflammatory process of contact hypersensitivity.

Methods

For sensitization, the abdomens of wild-type and ARHGAP25 deficient (KO) mice on a C57BL/6 background, as well as bone marrow chimeric mice, were coated with 3% TNCB (2-chloro-1,3,5-trinitrobenzene) or acetone in the control group. After five days, ears were treated with 1% TNCB for elicitation. Swelling of the ears caused by edema formation was evaluated by measuring the ear thickness. Afterward, ears were harvested, and histological analysis, investigation of leukocyte infiltration, cytokine production, and changes in relevant signaling pathways were carried out. ARHGAP25 expression at the mRNA and protein levels was measured using murine ear and human skin samples.

Results

ARHGAP25 expression increased in human patients suffering from contact dermatitis and in contact hypersensitivity induced in mice. Our data suggest that ARHGAP25 expression is infinitesimal in keratinocytes. In the CHS mouse model, the absence of ARHGAP25 mitigated the severity of inflammation in a leukocyte-dependent manner by reducing the infiltration of phagocytes and cytotoxic T cells. ARHGAP25 altered cytokine composition in the sensitization and elicitation phase of the disease. However, this protein did not affect T cell homing and activation in the sensitization phase.

Conclusion

Our findings suggest that ARHGAP25 is essential in developing contact hypersensitivity by modulating the cytokine environment and leukocyte infiltration. Based on these findings, we propose ARHGAP25 as a promising candidate for future therapeutic approaches and a potential ACD biomarker.

Response of epithelial cell lines from the rainbow trout gut and gill to ammonia

Rainbow trout epithelial cell lines from the gill, RTgill-W1, and gut, RTgutGC, were exposed to NH4Cl at 18-21 °C in L15 (basal medium) with fetal bovine serum and were found to undergo cytoplasmic vacuolization and cell death, depending on NH4Cl concentration and exposure time. Vacuolization arose within 24 h of cultures being exposed to 10-100 mM NH4Cl, and vacuoles disappeared over 24 h after NH4Cl-exposed cultures were returned to just L15/FBS. RTgill-W1 appeared more sensitive to vacuolization, with one indicator being the maximal proportion of vacuolated cells in a culture, which approached 100% in 50 mM NH4Cl for 72 h. RTgill-W1 also were more sensitive to NH4Cl-induced cell killing. For 7-d exposures, the inhibitory concentrations (IC50s) for the 50% loss of cell viability as evaluated with Alamar Blue were 30 mM NH4Cl for RTgill-W1 and 80 mM for RTgutGC. In a wound-healing assay, RTgutGC cells in 0.1 and 1 mM NH4Cl were able to migrate and cover a 500-μm gap in 5 d, like the control, but in 50 mM NH4Cl healing was blocked. In 10 mM NH4Cl, repair was slowed but by 14 d the gap was covered with cells and many of these were vacuolated. Overall, the results provide a foundation for using these two cell lines to study the physiology and toxicology of ammonia in fish.

An essential role for EROS in redox-dependent endothelial signal transduction

The chaperone protein EROS ("Essential for Reactive Oxygen Species") was recently discovered in phagocytes. EROS was shown to regulate the abundance of the ROS-producing enzyme NADPH oxidase isoform 2 (NOX2) and to control ROS-mediated cell killing. Reactive oxygen species are important not only in immune surveillance, but also modulate physiological signaling responses in multiple tissues. The roles of EROS have not been previously explored in the context of oxidant-modulated cell signaling. Here we show that EROS plays a key role in ROS-dependent signal transduction in vascular endothelial cells. We used siRNA-mediated knockdown and developed CRISPR/Cas9 knockout of EROS in human umbilical vein endothelial cells (HUVEC), both of which cause a significant decrease in the abundance of NOX2 protein, associated with a marked decrease in RAC1, a small G protein that activates NOX2. Loss of EROS also attenuates receptor-mediated hydrogen peroxide (H2O2) and Ca2+ signaling, disrupts cytoskeleton organization, decreases cell migration, and promotes cellular senescence. EROS knockdown blocks agonist-modulated eNOS phosphorylation and nitric oxide (NO●) generation. These effects of EROS knockdown are strikingly similar to the alterations in endothelial cell responses that we previously observed following RAC1 knockdown. Proteomic analyses following EROS or RAC1 knockdown in endothelial cells showed that reduced abundance of these two distinct proteins led to largely overlapping effects on endothelial biological processes, including oxidoreductase, protein phosphorylation, and endothelial nitric oxide synthase (eNOS) pathways. These studies demonstrate that EROS plays a central role in oxidant-modulated endothelial cell signaling by modulating NOX2 and RAC1.

Extracellular Matrix Deposition Defines the Duration of Cell Sheet Assembly from Human Adipose-Derived MSC

Cell sheet (CS) engineering using mesenchymal stromal cells (MSC) draws significant interest for regenerative medicine and this approach translates to clinical use for numerous indications. However, little is known of factors that define the timing of CS assembly from primary cultures. This aspect is important for planning CS delivery in autologous and allogeneic modes of use. We used a comparative in vitro approach with primary donors' (n = 14) adipose-derived MSCs and evaluated the impact of healthy subject's sex, MSC culture features (population doubling time and lag-phase), and extracellular matrix (ECM) composition along with factors related to connective tissue formations (α-SMA and FAP-α) on CS assembly duration. Using qualitative and quantitative analysis methods, we found that, in seeded MSCs, high contents of collagen I and collagen IV had a direct correlation with longer CS assembly duration. We found that short lag-phase cultures faster turned to a ready-to-use CS, while age, sex, fibronectin, laminin, α-SMA, and FAP-α failed to provide a significant correlation with the timing of assembly. In detachable CSs, FAP-α was negatively correlated with the duration of assembly, suggesting that its concentration rose over time and contributed to MSC activation, transitioning to α-SMA-positive myofibroblasts and ECM turnover. Preliminary data on cell density and collagen I deposition suggested that the TGF-β1 signaling axis is of pivotal importance for ECM composition and construct maturation.

Activation of Sestrin2 accelerates deep second-degree burn wound healing through PI3K/AKT pathway

Deep second-degree burns heal slowly, and promoting the healing process is a focus of clinical research. Sestrin2 is a stress-inducible protein with antioxidant and metabolic regulatory effects. However, its role during acute dermal and epidermal re-epithelialization in deep second-degree burns is unknown. In this study, we aimed to explore the role and molecular mechanism of sestrin2 in deep second-degree burns as a potential treatment target for burn wounds. To explore the effects of sestrin2 on burn wound healing, we established a deep second-degree burn mouse model. Then we detected the expression of sestrin2 by western blot and immunohistochemistry after obtaining the wound margin of full-thickness burned skin. The effects of sestrin2 on burn wound healing were explored in vivo and in vitro through interfering sestrin2 expression using siRNAs or the small molecule agonist of sestrin2, eupatilin. We also investigated the molecular mechanism of sestrin2 in promoting burn wound healing by western blot and CCK-8 assay. Our in vivo and in vitro deep second-degree burn wound healing model demonstrated that sestrin2 was promptly induced at murine skin wound edges. The small molecule agonist of sestrin2 accelerated the proliferation and migration of keratinocytes, as well as burn wound healing. Conversely, the healing of burn wounds was delayed in sestrin2-deficient mice and was accompanied by the secretion of inflammatory cytokines as well as the suppression of keratinocyte proliferation and migration. Mechanistically, sestrin2 promoted the phosphorylation of the PI3K/AKT pathway, and inhibition of PI3K/AKT pathway abrogated the promoting role of sestrin2 in keratinocyte proliferation and migration. Therefore, sestrin2 plays a critical role in activation of the PI3K/AKT pathway to promote keratinocyte proliferation and migration, as well as re-epithelialization in the process of deep second-degree burn wound repair.

Application of Electrochemical Oxidation for Water and Wastewater Treatment: An Overview

In recent years, the discharge of various emerging pollutants, chemicals, and dyes in water and wastewater has represented one of the prominent human problems. Since water pollution is directly related to human health, highly resistant and emerging compounds in aquatic environments will pose many potential risks to the health of all living beings. Therefore, water pollution is a very acute problem that has constantly increased in recent years with the expansion of various industries. Consequently, choosing efficient and innovative wastewater treatment methods to remove contaminants is crucial. Among advanced oxidation processes, electrochemical oxidation (EO) is the most common and effective method for removing persistent pollutants from municipal and industrial wastewater. However, despite the great progress in using EO to treat real wastewater, there are still many gaps. This is due to the lack of comprehensive information on the operating parameters which affect the process and its operating costs. In this paper, among various scientific articles, the impact of operational parameters on the EO performances, a comparison between different electrochemical reactor configurations, and a report on general mechanisms of electrochemical oxidation of organic pollutants have been reported. Moreover, an evaluation of cost analysis and energy consumption requirements have also been discussed. Finally, the combination process between EO and photocatalysis (PC), called photoelectrocatalysis (PEC), has been discussed and reviewed briefly. This article shows that there is a direct relationship between important operating parameters with the amount of costs and the final removal efficiency of emerging pollutants. Optimal operating conditions can be achieved by paying special attention to reactor design, which can lead to higher efficiency and more efficient treatment. The rapid development of EO for removing emerging pollutants from impacted water and its combination with other green methods can result in more efficient approaches to face the pressing water pollution challenge. PEC proved to be a promising pollutants degradation technology, in which renewable energy sources can be adopted as a primer to perform an environmentally friendly water treatment.

Guidance by followers ensures long-range coordination of cell migration through α-catenin mechanoperception

Morphogenesis, wound healing, and some cancer metastases depend upon the migration of cell collectives that need to be guided to their destination as well as coordinated with other cell movements. During zebrafish gastrulation, the extension of the embryonic axis is led by the mesendodermal polster that migrates toward the animal pole, followed by the axial mesoderm that undergoes convergence and extension. Here, we investigate how polster cells are guided toward the animal pole. Using a combination of precise laser ablations, advanced transplants, and functional as well as in silico approaches, we establish that each polster cell is oriented by its immediate follower cells. Each cell perceives the migration of followers, through E-cadherin/α-catenin mechanotransduction, and aligns with them. Therefore, directional information propagates from cell to cell over the whole tissue. Such guidance of migrating cells by followers ensures long-range coordination of movements and developmental robustness.

Accelerated Wound Healing and Keratinocyte Proliferation through PI3K/Akt/pS6 and VEGFR2 Signaling by Topical Use of Pleural Fluid

Impaired wound healing is an ongoing issue that cancer patients undergoing chemotherapy or radiotherapy face. Our previous study regarding lung-cancer-associated pleural fluid (LCPF) demonstrated its propensity to promote endothelial proliferation, migration, and angiogenesis, which are crucial features during cutaneous wound healing. Therefore, the current study aimed to investigate the effect of pleural fluid on cutaneous wound closure in vitro and in vivo using HaCaT keratinocytes and a full-thickness skin wound model, respectively. Both heart-failure-associated pleural fluid (HFPF) and LCPF were sequentially centrifuged and filtered to obtain a cell-free status. Treatment with HFPF and LCPF homogeneously induced HaCaT proliferation with cell cycle progression, migration, and MMP2 upregulation. Western blotting revealed increased PI3K/Akt phosphorylation and VEGFR2/VEGFA expression in HaCaT cells. When treated with the PI3K inhibitor, LCPF-induced keratinocyte proliferation was attenuated with decreased pS6 levels. By applying the VEGFR2 inhibitor, LCPF-induced keratinocyte proliferation was ameliorated by pS6 and MMP2 downregulation. The effect of LCPF-induced cell junction rearrangement was disrupted by co-treatment with a VEGFR2 inhibitor. Compared with a 0.9% saline dressing, LCPF significantly accelerated wound closure and re-epithelization when used as a dressing material in a full-thickness wound model. Histological analysis revealed increased neo-epidermis thickness and dermis collagen synthesis in the LCPF-treated group. Furthermore, LCPF treatment activated basal keratinocytes at the wound edge with the upregulation of Ki-67, VEGFA, and MMP2. Our preliminaries provided the benefit of wet dressing with pleural fluid to improve cutaneous wound closure through enhanced re-epithelization and disclosed future autologous application in cancer wound treatment.

Anti-Malignant Effect of Tensile Loading to Adherens Junctions in Cutaneous Squamous Cell Carcinoma Cells

Actomyosin contractility regulates various cellular processes including proliferation and differentiation while dysregulation of actomyosin activity contributes to cancer development and progression. Previously, we have reported that actomyosin-generated tension at adherens junctions is required for cell density-dependent inhibition of proliferation of normal skin keratinocytes. However, it remains unclear how actomyosin contractility affects the hyperproliferation ability of cutaneous squamous cell carcinoma (cSCC) cells. In this study, we find that actomyosin activity is impaired in cSCC cells both in vitro and in vivo. External application of tensile loads to adherens junctions by sustained mechanical stretch attenuates the proliferation of cSCC cells, which depends on intact adherens junctions. Forced activation of actomyosin of cSCC cells also inhibits their proliferation in a cell-cell contact-dependent manner. Furthermore, the cell cycle arrest induced by tensile loading to adherens junctions is accompanied by epidermal differentiation in cSCC cells. Our results show that the degree of malignant properties of cSCC cells can be reduced by applying tensile loads to adherens junctions, which implies that the mechanical status of adherens junctions may serve as a novel therapeutic target for cSCC.