Sticky business: orchestrating cellular signals at adherens junctions

Chitosan and hyaluronic acid in colorectal cancer therapy: A review on EMT regulation, metastasis, and overcoming drug resistance

Up to 90% of cancer-related fatalities could be attributed to metastasis. Therefore, understanding the mechanisms that facilitate tumor cell metastasis is beneficial for improving patient survival and results. EMT is considered the main process involved in the invasion and spread of CRC. Essential molecular components like Wnt, TGF-β, and PI3K/Akt play a role in controlling EMT in CRC, frequently triggered by various factors such as Snail, Twist, and ZEB1. These factors affect not only the spread of CRC but also determine the reaction to chemotherapy. The influence of non-coding RNAs, especially miRNAs and lncRNAs, on the regulation of EMT is clear in CRC. Exosomes, involved in cell-to-cell communication, can affect the TME and metastasis of CRC. Pharmacological substances and nanoparticles demonstrate promise as efficient modulators of EMT in CRC. Chitosan and HA are two major carbohydrate polymers with considerable potential in inhibiting CRC. Chitosan and HA can be employed to modify nanoparticles to enhance cargo transport for reducing CRC. Additionally, chitosan and HA-modified nanocarriers, which can be utilized as potential approaches in suppressing EMT and reversing drug resistance in CRC, can inhibit EMT and chemoresistance, crucial components in tumorigenesis.

Alteration of Cytoskeletal Proteins Leads to Retinal Degeneration in Drosophila

The eye holds a special fascination for many neuroscientists because of its meticulously organized structure. Vertebrates typically possess a simple camera-type eye, whereas the compound eye structure is predominantly observed in arthropods including model organism Drosophila melanogaster. Cell shape, cell polarization, and tissue integrity are the cell biological processes crucial for shaping the eye, which directly or indirectly depends on the cytoskeleton. Henceforth the cytoskeleton, specifically actin microfilaments, essentially has a dynamic role in the normal development and growth of eye structure. This review provides insight into the roles played by the actin cytoskeleton during the development and maintenance of the Drosophila eye.

Alpha T-catenin: a crucial tumor suppressor in cancer pathogenesis

Alpha T-catenin has recently been identified as a crucial tumor suppressor in various cancer types, with roles that go beyond just providing structural support in adherens junctions. This review brings together recent findings on alpha T-catenin's important involvement in key signaling pathways related to cancer progression. We present strong evidence of its regulatory role in Wnt signaling, a pathway often disrupted in colorectal cancer, and explain how it inhibits cell proliferation and tumor growth. We also discuss the significant downregulation of alpha T-catenin in colorectal cancers and its potential as a prognostic marker. Moreover, this review looks at how increasing alpha T-catenin levels can reduce tumor growth and spread, suggesting new therapeutic strategies. Additionally, we reveal alpha T-catenin's unexpected impact on NF-κB signaling in basal E-cadherin-negative breast cancer, expanding its importance across different cancer types. By bringing these findings together, we provide a thorough understanding of alpha T-catenin's tumor-suppressing actions, setting the stage for new targeted therapies and diagnostic tools in cancer treatment.

Epithelial UNC-23 limits mechanical stress to maintain glia-neuron architecture in C. elegans

For an organ to maintain correct architecture and function, its diverse cellular components must coordinate their size and shape. Although cell-intrinsic mechanisms driving homotypic cell-cell coordination are known, it is unclear how cell shape is regulated across heterotypic cells. We find that epithelial cells maintain the shape of neighboring sense-organ glia-neuron units in adult Caenorhabditis elegans (C. elegans). Hsp co-chaperone UNC-23/BAG2 prevents epithelial cell shape from deforming, and its loss causes head epithelia to stretch aberrantly during animal movement. In the sense-organ glia, amphid sheath (AMsh), this causes progressive fibroblast growth factor receptor (FGFR)-dependent disruption of the glial apical cytoskeleton. Resultant glial cell shape alteration causes concomitant shape change in glia-associated neuron endings. Epithelial UNC-23 maintenance of glia-neuron shape is specific both spatially, within a defined anatomical zone, and temporally, in a developmentally critical period. As all molecular components uncovered are broadly conserved across central and peripheral nervous systems, we posit that epithelia may similarly regulate glia-neuron architecture cross-species.

Circular RNAs in EMT-driven metastasis regulation: modulation of cancer cell plasticity, tumorigenesis and therapy resistance

The non-coding RNAs comprise a large part of human genome lack of capacity in encoding functional proteins. Among various members of non-coding RNAs, the circular RNAs (circRNAs) have been of importance in the pathogenesis of human diseases, especially cancer. The circRNAs have a unique closed loop structure and due to their stability, they are potential diagnostic and prognostic factors in cancer. The increasing evidences have highlighted the role of circRNAs in the modulation of proliferation and metastasis of cancer cells. On the other hand, metastasis has been responsible for up to 90% of cancer-related deaths in patients, requiring more investigation regarding the underlying mechanisms modulating this mechanism. EMT enhances metastasis and invasion of tumor cells, and can trigger resistance to therapy. The cells demonstrate dynamic changes during EMT including transformation from epithelial phenotype into mesenchymal phenotype and increase in N-cadherin and vimentin levels. The process of EMT is reversible and its reprogramming can disrupt the progression of tumor cells. The aim of current review is to understanding the interaction of circRNAs and EMT in human cancers and such interaction is beyond the regulation of cancer metastasis and can affect the response of tumor cells to chemotherapy and radiotherapy. The onco-suppressor circRNAs inhibit EMT, while the tumor-promoting circRNAs mediate EMT for acceleration of carcinogenesis. Moreover, the EMT-inducing transcription factors can be controlled by circRNAs in different human tumors.

The Good and the Bad of SHROOM3 in Kidney Development and Disease: A Narrative Review

Purpose of review

Multiple large-scale genome-wide association meta-analyses studies have reliably identified an association between genetic variants within the SHROOM3 gene and chronic kidney disease. This association extends to alterations in known markers of kidney disease including baseline estimated glomerular filtration rate, urinary albumin-to-creatinine ratio, and blood urea nitrogen. Yet, an understanding of the molecular mechanisms behind the association of SHROOM3 and kidney disease remains poorly communicated. We conducted a narrative review to summarize the current state of literature regarding the genetic and molecular relationships between SHROOM3 and kidney development and disease.

Sources of information

PubMed, PubMed Central, SCOPUS, and Web of Science databases, as well as review of references from relevant studies and independent Google Scholar searches to fill gaps in knowledge.

Methods

A comprehensive narrative review was conducted to explore the molecular mechanisms underlying SHROOM3 and kidney development, function, and disease.

Key findings

SHROOM3 is a unique protein, as it is the only member of the SHROOM group of proteins that regulates actin dynamics through apical constriction and apicobasal cell elongation. It holds a dichotomous role in the kidney, as subtle alterations in SHROOM3 expression and function can be both pathological and protective toward kidney disease. Genome-wide association studies have identified genetic variants near the transcription start site of the SHROOM3 gene associated with chronic kidney disease. SHROOM3 also appears to protect the glomerular structure and function in conditions such as focal segmental glomerulosclerosis. However, little is known about the exact mechanisms by which this protection occurs, which is why SHROOM3 binding partners remain an opportunity for further investigation.

Limitations

Our search was limited to English articles. No structured assessment of study quality was performed, and selection bias of included articles may have occurred. As we discuss future directions and opportunities, this narrative review reflects the academic views of the authors.

Distinct and targetable role of calcium-sensing receptor in leukaemia

Haematopoietic stem cells (HSC) reside in the bone marrow microenvironment (BMM), where they respond to extracellular calcium [eCa2+] via the G-protein coupled calcium-sensing receptor (CaSR). Here we show that a calcium gradient exists in this BMM, and that [eCa2+] and response to [eCa2+] differ between leukaemias. CaSR influences the location of MLL-AF9+ acute myeloid leukaemia (AML) cells within this niche and differentially impacts MLL-AF9+ AML versus BCR-ABL1+ leukaemias. Deficiency of CaSR reduces AML leukaemic stem cells (LSC) 6.5-fold. CaSR interacts with filamin A, a crosslinker of actin filaments, affects stemness-associated factors and modulates pERK, β-catenin and c-MYC signaling and intracellular levels of [Ca2+] in MLL-AF9+ AML cells. Combination treatment of cytarabine plus CaSR-inhibition in various models may be superior to cytarabine alone. Our studies suggest CaSR to be a differential and targetable factor in leukaemia progression influencing self-renewal of AML LSC via [eCa2+] cues from the BMM.

WNT enhancing signals in pancreatic cancer are transmitted by LGR6

The G-protein-coupled receptor LGR6 associates with ligands of the R-Spondin (RSPO) family to potentiate preexisting signals of the canonical WNT pathway. However, its importance in pancreatic ductal adenocarcinoma (PDAC) remains unclear. Here, we show that LGR6 is differentially expressed in various PDAC cell lines of mesenchymal and epithelial phenotype, respectively, siding with the latter subsets. LGR6 expression is altered based upon the cells' WNT activation status. Furthermore, extrinsic enhancement of WNT pathway signaling increased LGR6 expression suggestive of a reinforcing self-regulatory loop in highly WNT susceptible cells. Downregulation of LGR6 on the other hand, seemed to tamper those effects. Last, downregulation of LGR6 reduced cancer stemness as determined by functional in vitro assays. These findings shed new insights into regulatory mechanisms for the canonical WNT pathway in pancreatic cancer cells. It may also have potential value for treatment stratification of PDAC.

The co-expression pattern of VEGFR-2 with indicators related to proliferation, apoptosis, and differentiation of anagen hair follicles

An increasing number of studies show that vascular endothelial growth factor is an important regulator of hair growth, and involves in processes of hair follicle development by vascularization. Recently, VEGF receptor-2 (VEGFR-2) has been detected in epithelial cells of hair follicles, indicating that it may have a direct role in the biological activity of hair follicles. To explore how VEGFR-2 regulates hair follicle development, we investigated the co-expression pattern of VEGFR-2 with β-catenin, Bax, Bcl-2, involucrin, AE13 (hair cortex cytokeratin), keratin 16, keratin 14, and Laminin 5 by immunofluorescence double staining in anagen hair follicles of normal human scalp skin. The results of double staining immunofluorescence showed a strong overlapping and similar expression pattern for VEGFR-2 with β-catenin and Bcl-2, and revealing associated expression pattern with involucrin, AE13, keratin 14, keratin 16, and Laminin 5. These results elucidated that VEGFR-2 activation may participate in hair follicle differentiation, proliferation, and apoptosis in vivo.

Effect of Vitamin D on the Proliferation and Barrier of Atrophic Vaginal Epithelial Cells

Atrophic vaginitis is very common in postmenopausal women due to declining estrogen levels. Vitamin D plays an important role in promoting epithelial cell proliferation, migration and adhesion. We established a rat model of ovariectomy (OVX) induced atrophic vaginitis with the aim of investigating the effects of Vitamin D supplementation on the vaginal epithelial barrier. The results showed that ovariectomised rats had significantly higher vaginal pH, reduced Lactobacillus, significantly lower uterine and vaginal weights, and lower vaginal epithelial PCNA, occludin, and E-cadherin mRNA expression compared with sham-operated rats. Vitamin D supplementation could reduce the vaginal pH, promote the proliferation and keratinization of vaginal epithelial cells, enhance the expression of PCNA mRNA in vaginal tissues, and improve the vaginal and uterine atrophy. Vitamin D can also increase the expression of E-cadherin and occludin proteins in vaginal tissues, maintain the integrity of the vaginal epithelium, increase the number of Lactobacillus, and reduce pathogenic bacterial infections. In vitro experiments demonstrated that 1,25(OH)2D3 could promote the proliferation and migration of VK2/E6E7 vaginal epithelial cells and increase the expression of E-cadherin protein. In conclusion, we demonstrated that Vitamin D can regulate the expression of vaginal epithelial tight junction proteins, promotes cell proliferation, and improves vaginal atrophy due to estrogen deficiency.

Wnt/β-Catenin Signaling Pathway Is Necessary for the Specification but Not the Maintenance of the Mouse Retinal Pigment Epithelium

β-Catenin (Ctnnb1) has been shown to play critical roles in the development and maintenance of epithelial cells, including the retinal pigment epithelium (RPE). Ctnnb1 is not only a component of intercellular junctions in the epithelium, it also functions as a transcriptional regulator in the Wnt signaling pathway. To identify which of its functional modalities is critically involved in mouse RPE development and maintenance, we varied Ctnnb1 gene content and activity in mouse RPE lineage cells and tested their impacts on mouse eye development. We found that a Ctnnb1 double mutant (Ctnnb1dm), which exhibits impaired transcriptional activity, could not replace Ctnnb1 in the RPE, whereas Ctnnb1Y654E, which has reduced affinity for the junctions, could do so. Expression of the constitutively active Ctnnb1∆ex3 mutant also suppressed the development of RPE, instead facilitating a ciliary cell fate. However, the post-mitotic or mature RPE was insensitive to the loss, inactivation, or constitutive activation of Ctnnb1. Collectively, our results suggest that Ctnnb1 should be maintained within an optimal range to specify RPE through transcriptional regulation of Wnt target genes in the optic neuroepithelium.

In vitro models to study natural killer cell dynamics in the tumor microenvironment

Immunotherapy is revolutionizing cancer therapy. The rapid development of new immunotherapeutic strategies to treat solid tumors is posing new challenges for preclinical research, demanding novel in vitro methods to test treatments. Such methods should meet specific requirements, such as enabling the evaluation of immune cell responses like cytotoxicity or cytokine release, and infiltration into the tumor microenvironment using cancer models representative of the original disease. They should allow high-throughput and high-content analysis, to evaluate the efficacy of treatments and understand immune-evasion processes to facilitate development of new therapeutic targets. Ideally, they should be suitable for personalized immunotherapy testing, providing information for patient stratification. Consequently, the application of in vitro 3-dimensional (3D) cell culture models, such as tumor spheroids and organoids, is rapidly expanding in the immunotherapeutic field, coupled with the development of novel imaging-based techniques and -omic analysis. In this paper, we review the recent advances in the development of in vitro 3D platforms applied to natural killer (NK) cell-based cancer immunotherapy studies, highlighting the benefits and limitations of the current methods, and discuss new concepts and future directions of the field.

E-cadherin and aquaporin-3 are downregulated in wound edges of human chronic wounds

Chronic wounds are defined as wounds that fail to proceed through the normal phases of wound healing; a complex process involving different dynamic events including migration of keratinocytes in the epidermis. Chronic wounds are estimated to affect 1-2% of the human population worldwide and are a major socioeconomic burden. The prevalence of chronic wounds is expected to increase with the rising number of elderly and patients with diabetes and obesity, who are at high risk of developing chronic wounds. Since E-cadherin and the water channel aquaporin-3 are important for both skin function and cell migration, and aquaporin-3 is furthermore involved in wound healing of the skin demonstrated by impaired wound healing in aquaporin-3-null mice, we hypothesized that E-cadherin and aquaporin-3 expression may be dysregulated in chronic wounds. Therefore, we investigated the expression of E-cadherin and aquaporin-3 in biopsies from the edges of chronic wounds from human patients. This was accomplished by immunohistochemical stainings of E-cadherin and aquaporin-3 on serial sections followed by qualitative evaluation of staining patterns, which revealed low expression of both E-cadherin and aquaporin-3 at the wound edge. Future studies are needed to reveal if this downregulation is associated with the pathophysiology of chronic wounds.

Claudin-4-adhesion signaling drives breast cancer metabolism and progression via liver X receptor β

BACKGROUND

Cell adhesion is indispensable for appropriate tissue architecture and function in multicellular organisms. Besides maintaining tissue integrity, cell adhesion molecules, including tight-junction proteins claudins (CLDNs), exhibit the signaling abilities to control a variety of physiological and pathological processes. However, it is still fragmentary how cell adhesion signaling accesses the nucleus and regulates gene expression.

METHODS

By generating a number of knockout and rescued human breast cell lines and comparing their phenotypes, we determined whether and how CLDN4 affected breast cancer progression in vitro and in vivo. We also identified by RNA sequencing downstream genes whose expression was altered by CLDN4-adhesion signaling. Additionally, we analyzed by RT-qPCR the CLDN4-regulating genes by using a series of knockout and add-back cell lines. Moreover, by immunohistochemistry and semi-quantification, we verified the clinicopathological significance of CLDN4 and the nuclear receptor LXRβ (liver X receptor β) expression in breast cancer tissues from 187 patients.

RESULTS

We uncovered that the CLDN4-adhesion signaling accelerated breast cancer metabolism and progression via LXRβ. The second extracellular domain and the carboxy-terminal Y197 of CLDN4 were required to activate Src-family kinases (SFKs) and the downstream AKT in breast cancer cells to promote their proliferation. Knockout and rescue experiments revealed that the CLDN4 signaling targets the AKT phosphorylation site S432 in LXRβ, leading to enhanced cell proliferation, migration, and tumor growth, as well as cholesterol homeostasis and fatty acid metabolism, in breast cancer cells. In addition, RT-qPCR analysis showed the CLDN4-regulated genes are classified into at least six groups according to distinct LXRβ- and LXRβS432-dependence. Furthermore, among triple-negative breast cancer subjects, the "CLDN4-high/LXRβ-high" and "CLDN4-low and/or LXRβ-low" groups appeared to exhibit poor outcomes and relatively favorable prognoses, respectively.

CONCLUSIONS

The identification of this machinery highlights a link between cell adhesion and transcription factor signalings to promote metabolic and progressive processes of malignant tumors and possibly to coordinate diverse physiological and pathological events.

Differential bumble bee gene expression associated with pathogen infection and pollen diet

BACKGROUND

Diet and parasitism can have powerful effects on host gene expression. However, how specific dietary components affect host gene expression that could feed back to affect parasitism is relatively unexplored in many wild species. Recently, it was discovered that consumption of sunflower (Helianthus annuus) pollen reduced severity of gut protozoan pathogen Crithidia bombi infection in Bombus impatiens bumble bees. Despite the dramatic and consistent medicinal effect of sunflower pollen, very little is known about the mechanism(s) underlying this effect. However, sunflower pollen extract increases rather than suppresses C. bombi growth in vitro, suggesting that sunflower pollen reduces C. bombi infection indirectly via changes in the host. Here, we analyzed whole transcriptomes of B. impatiens workers to characterize the physiological response to sunflower pollen consumption and C. bombi infection to isolate the mechanisms underlying the medicinal effect. B. impatiens workers were inoculated with either C. bombi cells (infected) or a sham control (un-infected) and fed either sunflower or wildflower pollen ad libitum. Whole abdominal gene expression profiles were then sequenced with Illumina NextSeq 500 technology.

RESULTS

Among infected bees, sunflower pollen upregulated immune transcripts, including the anti-microbial peptide hymenoptaecin, Toll receptors and serine proteases. In both infected and un-infected bees, sunflower pollen upregulated putative detoxification transcripts and transcripts associated with the repair and maintenance of gut epithelial cells. Among wildflower-fed bees, infected bees downregulated immune transcripts associated with phagocytosis and the phenoloxidase cascade.

CONCLUSIONS

Taken together, these results indicate dissimilar immune responses between sunflower- and wildflower-fed bumble bees infected with C. bombi, a response to physical damage to gut epithelial cells caused by sunflower pollen, and a strong detoxification response to sunflower pollen consumption. Identifying host responses that drive the medicinal effect of sunflower pollen in infected bumble bees may broaden our understanding of plant-pollinator interactions and provide opportunities for effective management of bee pathogens.

Multi-level Force-dependent Allosteric Enhancement of αE-catenin Binding to F-actin by Vinculin

Classical cadherins are transmembrane proteins whose extracellular domains link neighboring cells, and whose intracellular domains connect to the actin cytoskeleton via β-catenin and α-catenin. The cadherin-catenin complex transmits forces that drive tissue morphogenesis and wound healing. In addition, tension-dependent changes in αE-catenin conformation enables it to recruit the actin-binding protein vinculin to cell-cell junctions, which contributes to junctional strengthening. How and whether multiple cadherin-complexes cooperate to reinforce cell-cell junctions in response to load remains poorly understood. Here, we used single-molecule optical trap measurements to examine how multiple cadherin-catenin complexes interact with F-actin under load, and how this interaction is influenced by the presence of vinculin. We show that force oriented toward the (-) end of the actin filament results in mean lifetimes 3-fold longer than when force was applied towards the barbed (+) end. We also measured force-dependent actin binding by a quaternary complex comprising the cadherin-catenin complex and the vinculin head region, which cannot itself bind actin. Binding lifetimes of this quaternary complex increased as additional complexes bound F-actin, but only when load was oriented toward the (-) end. In contrast, the cadherin-catenin complex alone did not show this form of cooperativity. These findings reveal multi-level, force-dependent regulation that enhances the strength of the association of multiple cadherin/catenin complexes with F-actin, conferring positive feedback that may strengthen the junction and polarize F-actin to facilitate the emergence of higher-order cytoskeletal organization.

E-cadherin in developing murine T cells controls spindle alignment and progression through β-selection

A critical stage of T cell development is β-selection; at this stage, the T cell receptor β (TCRβ) chain is generated, and the developing T cell starts to acquire antigenic specificity. Progression through β-selection is assisted by low-affinity interactions between the nascent TCRβ chain and peptide presented on stromal major histocompatibility complex and cues provided by the niche. In this study, we identify a cue within the developing T cell niche that is critical for T cell development. E-cadherin mediates cell-cell interactions and influences cell fate in many developmental systems. In developing T cells, E-cadherin contributed to the formation of an immunological synapse and the alignment of the mitotic spindle with the polarity axis during division, which facilitated subsequent T cell development. Collectively, these data suggest that E-cadherin facilitates interactions with the thymic niche to coordinate the β-selection stage of T cell development.

Ultrastructural Characteristics of Finger-Like Membrane Protrusions in Cell Competition

A small number of oncogenic mutated cells sporadically arise within the epithelial monolayer. Newly emerging Ras- or Src-transformed epithelial cells are often apically eliminated during competitive interactions between normal and transformed cells. Our recent electron microscopy (EM) analyses revealed that characteristic finger-like membrane protrusions are formed at the interface between normal and RasV12-transformed cells via the cdc42–formin-binding protein 17 (FBP17) pathway, potentially playing a positive role in intercellular recognition during apical extrusion. However, the spatial distribution and ultrastructural characteristics of finger-like protrusions remain unknown. In this study, we performed both X–Y and X–Z EM analyses of finger-like protrusions during the apical extrusion of RasV12-transformed cells. Quantification of the distribution and widths of the protrusions showed comparable results between the X–Y and X–Z sections. Finger-like protrusions were observed throughout the cell boundary between normal and RasV12 cells, except for apicalmost tight junctions. In addition, a non-cell-autonomous reduction in protrusion widths was observed between RasV12 cells and surrounding normal cells under the mix culture condition. In the finger-like protrusions, intercellular adhesions via thin electron-dense plaques were observed, implying that immature and transient forms of desmosomes, adherens junctions or unknown weak adhesions were distributed. Interestingly, unlike RasV12-transformed cells, Src-transformed cells form fewer evident protrusions, and FBP17 in Src cells is dispensable for apical extrusion. Collectively, these results suggest that the dynamic reorganization of intercellular adhesions via finger-like protrusions may positively control cell competition between normal and RasV12-transformed cells. Furthermore, our data indicate a cell context–dependent diversity in the modes of apical extrusion.

Ruthenium(ii)-arene complexes as anti-metastatic agents, and related techniques

With the discovery of cisplatin, a vast area of applications of metallodrugs in cancer treatment was opened but due to the side effects caused by the cisplatin complexes, researchers began to look for alternatives with similar anticancer properties but fewer side effects. Ruthenium was found to be a promising candidate, considering its significant anticancer properties and low side effects. Several ruthenium complexes, viz. NAMI-A, KP1019, KP1339, and TLD1433, have entered clinical trials. Some other arene ruthenium complexes such as RM175 and RAPTA-C have also entered clinical trials but very few of them have shown anti-metastatic properties. Herein, we provide information and probable mechanistic pathways for ruthenium(ii)-arene complexes that have been studied, so far, for their anti-metastatic activities. Also, we discuss the techniques and their significance for determining the anti-metastatic effects of the complexes.

Epithelial integrity, junctional complexes, and biomarkers associated with intestinal functions

An intact intestinal barrier is crucial for immune homeostasis and its impairment activates the immune system and may result in chronic inflammation. The epithelial cells of the intestinal barrier are connected by tight junctions, which form an anastomosing network sealing adjacent epithelial cells. Tight junctions are composed of transmembrane and cytoplasmic scaffolding proteins. Transmembrane tight junction proteins at the apical-lateral membrane of the cell consist of occludin, claudins, junctional adhesion molecules, and tricellulin. Cytoplasmic scaffolding proteins, including zonula occludens, cingulin and afadin, provide a direct link between transmembrane tight junction proteins and the intracellular cytoskeleton. Each individual component of the tight junction network closely interacts with each other to form an efficient intestinal barrier. This review aims to describe the molecular structure of intestinal epithelial tight junction proteins and to characterize their organization and interaction. Moreover, clinically important biomarkers associated with impairment of gastrointestinal integrity are discussed.

Angiocrine Regulation of Epithelial Barrier Integrity in Inflammatory Bowel Disease

Inflammatory bowel disease describes chronic inflammatory disorders. The incidence of the disease is rising. A major step in disease development is the breakdown of the epithelial cell barrier. Numerous blood vessels are directly located underneath this barrier. Diseased tissues are heavily vascularized and blood vessels significantly contribute to disease progression. The gut-vascular barrier (GVB) is an additional barrier controlling the entry of substances into the portal circulation and to the liver after passing the first epithelial barrier. The presence of the GVB rises the question, whether the vascular and endothelial barriers may communicate bi-directionally in the regulation of selective barrier permeability. Communication from epithelial to endothelial cells is well-accepted. In contrast, little is known on the respective backwards communication. Only recently, perfusion-independent angiocrine functions of endothelial cells were recognized in a way that endothelial cells release specific soluble factors that may directly act on the epithelial barrier. This review discusses the putative involvement of angiocrine inter-barrier communication in the pathogenesis of IBD.

Novel Approaches of Dysregulating Lysosome Functions in Cancer Cells by Specific Drugs and Its Nanoformulations: A Smart Approach of Modern Therapeutics

The smart strategy of cancer cells to bypass the caspase-dependent apoptotic pathway has led to the discovery of novel anti-cancer approaches including the targeting of lysosomes. Recent discoveries observed that lysosomes perform far beyond just recycling of cellular waste, as these organelles are metabolically very active and mediate several signalling pathways to sense the cellular metabolic status. These organelles also play a significant role in mediating the immune system functions. Thus, direct or indirect lysosome-targeting with different drugs can be considered a novel therapeutic approach in different disease including cancer. Recently, some anticancer lysosomotropic drugs (eg, nortriptyline, siramesine, desipramine) and their nanoformulations have been engineered to specifically accumulate within these organelles. These drugs can enhance lysosome membrane permeabilization (LMP) or disrupt the activity of resident enzymes and protein complexes, like v-ATPase and mTORC1. Other anticancer drugs like doxorubicin, quinacrine, chloroquine and DQ661 have also been used which act through multi-target points. In addition, autophagy inhibitors, ferroptosis inducers and fluorescent probes have also been used as novel theranostic agents. Several lysosome-specific drug nanoformulations like mixed charge and peptide conjugated gold nanoparticles (AuNPs), Au-ZnO hybrid NPs, TPP-PEG-biotin NPs, octadecyl-rhodamine-B and cationic liposomes, etc. have been synthesized by diverse methods. These nanoformulations can target cathepsins, glucose-regulated protein 78, or other lysosome specific proteins in different cancers. The specific targeting of cancer cell lysosomes with drug nanoformulations is quite recent and faces tremendous challenges like toxicity concerns to normal tissues, which may be resolved in future research. The anticancer applications of these nanoformulations have led them up to various stages of clinical trials. Here in this review article, we present the recent updates about the lysosome ultrastructure, its cross-talk with other organelles, and the novel strategies of targeting this organelle in tumor cells as a recent innovative approach of cancer management.

Role of microbiota and related metabolites in gastrointestinal tract barrier function in NAFLD

The Gastrointestinal (GI) tract is composed of four main barriers: microbiological, chemical, physical and immunological. These barriers play important roles in maintaining GI tract homeostasis. In the crosstalk between these barriers, microbiota and related metabolites have been shown to influence GI tract barrier integrity, and alterations of the gut microbiome might lead to an increase in intestinal permeability. As a consequence, translocation of bacteria and their products into the circulatory system increases, reaching proximal and distal tissues, such as the liver. One of the most prevalent chronic liver diseases, Nonalcoholic Fatty Liver Disease (NAFLD), has been associated with an altered gut microbiota and barrier integrity. However, the causal link between them has not been fully elucidated yet. In this review, we aim to highlight relevant bacterial taxa and their related metabolites affecting the GI tract barriers in the context of NAFLD, discussing their implications in gut homeostasis and in disease.

Oral administration of EGCG solution equivalent to daily achievable dosages of regular tea drinkers effectively suppresses miR483-3p induced metastasis of hepatocellular carcinoma cells in mice

The effect of non-cytotoxic doses of epigallocatechin-3-gallate (EGCG) on the metastatic capability of human hepatocellular carcinoma (HCC) cells was investigated in vitro and in vivo. miR483-3p, a microRNA whose expression correlates inversely with survival and positively with disease progression in HCC patients, was found to promote HCC cell migration and invasion in vitro as well as lung metastasis in nude mice established by the tail-vein injection of HCC cells. The induction of reactive oxygen species (ROS) and downregulation of antioxidant defense factors Nrf2 and SOD2 appeared to be an important underlying mechanism and treatment with a non-cytotoxic dose of EGCG effectively reversed the miR483-3p-induced enhancement of HCC cell migration and invasion in vitro. Moreover, administration through drinking water at doses (0.1% and 0.5% EGCG solution, respectively) equivalent to the intake of regular to heavy tea drinkers could also significantly inhibit lung metastasis of HCC cells based on the estimation from the USDA Database for the Flavonoid Content of Selected Foods and FDA guidelines for the conversion of animal dose to human equivalent dose. EGCG also significantly counteracted the miR483-3p-induced alteration in the expression of epithelial-mesenchymal transition (EMT) markers, E-cadherin and vimentin, and downregulated the endogenous expression of miR483-3p in HCC cells through an epigenetic mechanism that led to the hypermethylation of the miR483-3p promoter region. The data from our study illustrate that miR483-3p promotes HCC metastasis likely through the induction of oxidative stress and uncover a novel role of EGCG for protection against miR483-3p-mediated HCC metastasis via the epigenetic modulation of miR483-3p expression. These findings therefore provide further evidence supporting that regular tea consumption may contribute to protection against miR-483-3p-induced ROS and the associated HCC progression.

Onset of taste bud cell renewal starts at birth and coincides with a shift in SHH function

Embryonic taste bud primordia are specified as taste placodes on the tongue surface and differentiate into the first taste receptor cells (TRCs) at birth. Throughout adult life, TRCs are continually regenerated from epithelial progenitors. Sonic hedgehog (SHH) signaling regulates TRC development and renewal, repressing taste fate embryonically, but promoting TRC differentiation in adults. Here, using mouse models, we show TRC renewal initiates at birth and coincides with onset of SHHs pro-taste function. Using transcriptional profiling to explore molecular regulators of renewal, we identified Foxa1 and Foxa2 as potential SHH target genes in lingual progenitors at birth and show that SHH overexpression in vivo alters FoxA1 and FoxA2 expression relevant to taste buds. We further bioinformatically identify genes relevant to cell adhesion and cell locomotion likely regulated by FOXA1;FOXA2 and show that expression of these candidates is also altered by forced SHH expression. We present a new model where SHH promotes TRC differentiation by regulating changes in epithelial cell adhesion and migration.

The region-selective regulation of endothelial claudin-5 expression and signaling in brain health and disorders

The neurovascular unit (NVU) consists of neurons, glial cells, microvascular cells, and extracellular matrix, and is involved in a variety of physiological and pathological processes in the central nervous system (CNS). Within the NVU, the microvascular endothelial cells and pericytes principally contribute to maintaining the integrity of the blood-brain barrier (BBB). Various types of cells are connected to each other in the NVU by diverse cell adhesion molecules, of which claudin-5 (CLDN5) is by far the most abundantly expressed tight-junction protein in brain microvascular endothelial cells and absolutely required for the maintenance of the BBB. This review highlights recent progress in understanding the region-specific regulation and dysregulation of CLDN5 expression in CNS health and disorders. We also discuss how CLDN5 expression is regionally disrupted within the NVU. In addition, we focus on the link between cell adhesion and transcription factor signalings and describe the possible involvement of CLDN5-adhesion signaling in brain health and disorders.

Ephrin receptor A2, the epithelial receptor for Epstein-Barr virus entry, is not available for efficient infection in human gastric organoids

Epstein-Barr virus (EBV) is best known for infection of B cells, in which it usually establishes an asymptomatic lifelong infection, but is also associated with the development of multiple B cell lymphomas. EBV also infects epithelial cells and is associated with all cases of undifferentiated nasopharyngeal carcinoma (NPC). EBV is etiologically linked with at least 8% of gastric cancer (EBVaGC) that comprises a genetically and epigenetically distinct subset of GC. Although we have a very good understanding of B cell entry and lymphomagenesis, the sequence of events leading to EBVaGC remains poorly understood. Recently, ephrin receptor A2 (EPHA2) was proposed as the epithelial cell receptor on human cancer cell lines. Although we confirm some of these results, we demonstrate that EBV does not infect healthy adult stem cell-derived gastric organoids. In matched pairs of normal and cancer-derived organoids from the same patient, EBV only reproducibly infected the cancer organoids. While there was no clear pattern of differential expression between normal and cancer organoids for EPHA2 at the RNA and protein level, the subcellular location of the protein differed markedly. Confocal microscopy showed EPHA2 localization at the cell-cell junctions in primary cells, but not in cancer cell lines. Furthermore, histologic analysis of patient tissue revealed the absence of EBV in healthy epithelium and presence of EBV in epithelial cells from inflamed tissue. These data suggest that the EPHA2 receptor is not accessible to EBV on healthy gastric epithelial cells with intact cell-cell contacts, but either this or another, yet to be identified receptor may become accessible following cellular changes induced by inflammation or transformation, rendering changes in the cellular architecture an essential prerequisite to EBV infection.

PSF functions as a repressor of hypoxia-induced angiogenesis by promoting mitochondrial function

BACKGROUND

Abnormal neovascularization is the most common cause of blindness, and hypoxia alters tissue metabolism, function, and morphology. HIF-1α, the transcriptional activator of VEGF, has intricate mechanisms of nuclear translocation and activation, but its signal termination mechanisms remain unclear.

METHODS

We investigated the role of polypyrimidine tract-binding protein-associated splicing factor (PSF) in cellular energy production, migration, and proliferation by targeting HIF-1α in vivo and in vitro PSF plasmids were transfected with liposome 2000 transfection reagent. Young C57/BL6J mice were kept in a hyperoxia environment, followed by indoor air, resulting in oxygen-induced retinopathy. Oxygen-induced retinopathy (OIR) animals were randomly divided into three groups: OIR group, OIR + vector group (OIR cubs treated with rAAV vector) and OIR + PSF group (OIR cubs treated with rAAV-PSF). Age-matched C57/BL6J mice were used as controls and exposed to constant normoxic conditions. The animals were executed and their pupils were subjected to subsequent experiments. The metabolic spectrum was analyzed by Seahorse XFe96 flux analyzer, and OCR and extracellular acidification rate were quantified at the same time.

RESULTS

PSF ameliorated retinal neovascularization and corrected abnormal VEGF expression in mice with oxygen-induced retinopathy and reduced intra-retinal neovascularization in Vldlr - / - mice. PSF reprogrammed mitochondrial bioenergetics and inhibited the transition of endothelial cells after hypoxia, suggesting its involvement in pathological angiogenesis.Ectopic PSF expression inhibited hypoxia-induced HIF-1α activation in the nucleus by recruiting Hakai to the PSF/HIF-1α complex, causing HIF-1α inhibition. PSF knockdown increased hypoxia-stimulated HIF-1α reactions. These hypoxia-dependent processes may play a vital role in cell metabolism, migration, and proliferation. Thus, PSF is a potential treatment target in neovascularization-associated ophthalmopathy.

CONCLUSION

This is the first study showing that PSF inhibits HIF-1α via recruitment of Hakai, modulates mitochondrial oxidation and glycolysis, and downregulates VEGF expression under hypoxia. We propose a new HIF-1 α/Hakai regulatory mechanism that may play a vital role in the pathogenesis of neovascularization in ophthalmopathy. PSF-Hakai-HIF-1α signaling pathway under hypoxia condition. Schematic diagram showing that the PSF-Hakai-HIF-1α signaling pathway. Under hypoxia condition, PSF-Hakai complex regulate HIF-1α signaling, thus inhibiting downstream target gene VEGF, cell metabolism and angiogenesis eventually. Video Abstract: Detailed information of Materials and Methods.

Hydroxyapatite Particle Density Regulates Osteoblastic Differentiation Through β-Catenin Translocation

Substrate surface characteristics such as roughness, wettability and particle density are well-known contributors of a substrate's overall osteogenic potential. These characteristics are known to regulate cell mechanics as well as induce changes in cell stiffness, cell adhesions, and cytoskeletal structure. Pro-osteogenic particles, such as hydroxyapatite, are often incorporated into a substrate to enhance the substrates osteogenic potential. However, it is unknown which substrate characteristic is the key regulator of osteogenesis. This is partly due to the lack of understanding of how these substrate surface characteristics are transduced by cells. In this study substrates composed of polycaprolactone (PCL) and carbonated hydroxyapatite particles (HAp) were synthesized. HAp concentration was varied, and a range of surface characteristics created. The effect of each substrate characteristic on osteoblastic differentiation was then examined. We found that, of the characteristics examined, only HAp density, and indeed a specific density (85 particles/cm²), significantly increased osteoblastic differentiation. Further, an increase in focal adhesion maturation and turnover was observed in cells cultured on this substrate. Moreover, β-catenin translocation from the membrane bound cell fraction to the nucleus was more rapid in cells on the 85 particle/cm² substrate compared to cells on tissue culture polystyrene. Together, these data suggest that particle density is one pivotal factor in determining a substrates overall osteogenic potential. Additionally, the observed increase in osteoblastic differentiation is a at least partly the result of β-catenin translocation and transcriptional activity suggesting a β-catenin mediated mechanism by which substrate surface characteristics are transduced.

Thymosin β4 is essential for adherens junction stability and epidermal planar cell polarity

Planar cell polarity (PCP) is essential for tissue morphogenesis and homeostasis; however, the mechanisms that orchestrate the cell shape and packing dynamics required to establish PCP are poorly understood. Here, we identified a major role for the globular (G)-actin-binding protein thymosin-β4 (TMSB4X) in PCP establishment and cell adhesion in the developing epidermis. Depletion of Tmsb4x in mouse embryos hindered eyelid closure and hair-follicle angling owing to PCP defects. Tmsb4x depletion did not preclude epidermal cell adhesion in vivo or in vitro; however, it resulted in abnormal structural organization and stability of adherens junction (AJ) due to defects in filamentous (F)-actin and G-actin distribution. In cultured keratinocytes, TMSB4X depletion increased the perijunctional G/F-actin ratio and decreased G-actin incorporation into junctional actin networks, but it did not change the overall actin expression level or cellular F-actin content. A pharmacological treatment that increased the G/F-actin ratio and decreased actin polymerization mimicked the effects of Tmsb4x depletion on both AJs and PCP. Our results provide insights into the regulation of the actin pool and its involvement in AJ function and PCP establishment.

Highlighted Article: By regulating actin pool distribution and incorporation into junctional actin networks, thymosin β4 regulates cell–cell adhesion, planar cell polarity and epidermal morphogenesis.

The tight junction and the epithelial barrier in coeliac disease

Epithelial barriers are essential to maintain multicellular organisms well compartmentalized and protected from external environment. In the intestine, the epithelial layer orchestrates a dynamic balance between nutrient absorption and prevention of microorganisms, and antigen intrusion. Intestinal barrier function has been shown to be altered in coeliac disease but whether it contributes to the pathogenesis development or if it is merely a phenomenon secondary to the aberrant immune response is still unknown. The tight junction complexes are multiprotein cell-cell adhesions that seal the epithelial intercellular space and regulate the paracellular permeability of ions and solutes. These structures have a fundamental role in epithelial barrier integrity as well as in signaling mechanisms that control epithelial-cell polarization, the formation of apical domains and cellular processes such as cell proliferation, migration, differentiation, and survival. In coeliac disease, the molecular structures and function of tight junctions appear disrupted and are not completely recovered after treatment with gluten-free diet. Moreover, zonulin, the only known physiological regulator of the tight junction permeability, appears augmented in autoimmune conditions associated with TJ dysfunction, including coeliac disease. This chapter will examine recent discoveries about the molecular architecture of tight junctions and their functions. We will discuss how different factors contribute to tight junction disruption and intestinal barrier impairment in coeliac disease. To conclude, new insights into zonulin-driven disruption of tight junction structures and barrier integrity in coeliac disease are presented together with the advancements in novel therapy to treat the barrier defect seen in pathogenesis.

Regulation of Epithelial-Mesenchymal Plasticity by the E3 Ubiquitin-Ligases in Cancer

The epithelial-mesenchymal plasticity (EMP) is a process by which epithelial cells acquire the ability to dynamically switch between epithelial and mesenchymal phenotypic cellular states. Epithelial cell plasticity in the context of an epithelial-to-mesenchymal transition (EMT) confers increased cell motility, invasiveness and the ability to disseminate to distant sites and form metastasis. The modulation of molecularly defined targets involved in this process has become an attractive therapeutic strategy against cancer. Protein degradation carried out by ubiquitination has gained attention as it can selectively degrade proteins of interest. In the ubiquitination reaction, the E3 ubiquitin-ligases are responsible for the specific binding of ubiquitin to a small subset of target proteins, and are considered promising anticancer drug targets. In this review, we summarize the role of the E3 ubiquitin-ligases that control targeted protein degradation in cancer-EMT, and we highlight the potential use of the E3 ubiquitin-ligases as drug targets for the development of small-molecule drugs against cancer.

Diesel exhaust particle exposure reduces expression of the epithelial tight junction protein Tricellulin

BACKGROUND

While exposure to diesel exhaust particles has been linked to aberrant immune responses in allergic diseases such as asthma, little attention has been paid to their effects on the airway epithelial barrier. In this study, we sought to determine the effect of diesel exhaust exposure on airway epithelial barrier function and composition using in vitro and in vivo model systems.

METHODS

16HBE14o- human bronchial epithelial cells were grown on collagen coated Transwell inserts and exposed to 5 to 50 μg/cm2 SRM 2975 diesel particulate matter (DEP) suspended in cell culture medium or vehicle controls. Changes in barrier function were assessed by measuring transepithelial electrical resistance (TEER) and permeability to 4 kDa FITC Dextran. Neonatal BALB/c mice were exposed to aerosolized DEP (255 ± 89 μg/m3; 2 h per day for 5 days) and changes in the tight junction protein Tricellulin were assessed 2 weeks post exposure.

RESULTS

A six-hour incubation of epithelial cells with diesel exhaust particles caused a significant concentration-dependent reduction in epithelial barrier integrity as measured by decreased TEER and increased permeability to 4 kDa FITC-Dextran. This reduction in epithelial barrier integrity corresponded to a significant reduction in expression of the tight junction protein Tricellulin. siRNA mediated knockdown of Tricellulin recapitulated changes in barrier function caused by DEP exposure. Neonatal exposure to aerosolized DEP caused a significant reduction in lung Tricellulin 2 weeks post exposure at both the protein and mRNA level.

CONCLUSION

Short term exposure to DEP causes a significant reduction in epithelial barrier integrity through a reduction in the tight junction protein Tricellulin. Neonatal exposure to aerosolized DEP caused a significant and sustained reduction in Tricellulin protein and mRNA in the lung, suggesting that early life exposure to inhaled DEP may cause lasting changes in airway epithelial barrier function.

ZNF582 hypermethylation promotes metastasis of nasopharyngeal carcinoma by regulating the transcription of adhesion molecules Nectin-3 and NRXN3

Background

Epigenetic regulation plays an important role in the development and progression of nasopharyngeal carcinoma (NPC). However, the epigenetic mechanisms underlying NPC metastasis remains poorly understood. We aimed to find functional genes which regulate the metastasis of NPC and identify therapeutic targets for NPC treatment.

Methods

Bisulfite pyrosequencing was used to analyze zinc finger protein 582 (ZNF582) methylation in NPC tissues and cell lines. Quantitative reverse transcription‐polymerase chain reaction (qRT‐PCR) and Western blotting were used to determine the expression of ZNF582. In vitro and in vivo experiments were performed to evaluate the biological function of ZNF582 in NPC. ZNF582‐targeting genes were identified by chromatin immunoprecipitation sequencing (ChIP‐seq) and were confirmed by ChIP‐qPCR and luciferase assay.

Results

ZNF582 promoter was hypermethylated in NPC, and both the mRNA and protein levels of ZNF582 were down‐regulated in NPC tissues and cell lines. The restoration of ZNF582 inhibited NPC migration, invasion, and metastasis, while the knockdown of ZNF582 promoted NPC migration, invasion, and metastasis in vitro and in vivo. ZNF582 directly regulated the transcription and expression of adhesion molecules Nectin‐3 and NRXN3. Both Nectin‐3 and NRXN3 were identified as functional targets of ZNF582, and the restoration or abrogation of these genes reversed the tumor suppressor effect of ZNF582 in NPC metastasis.

Conclusions

ZNF582 acts as a tumor suppressor gene in NPC by regulating the transcription and expression of adhesion molecules Nectin‐3 and NRXN3, which may provide novel therapeutic targets for NPC treatment.

Developmental potential of aneuploid human embryos cultured beyond implantation

Aneuploidy, the presence of an abnormal number of chromosomes, is a major cause of early pregnancy loss in humans. Yet, the developmental consequences of specific aneuploidies remain unexplored. Here, we determine the extent of post-implantation development of human embryos bearing common aneuploidies using a recently established culture platform. We show that while trisomy 15 and trisomy 21 embryos develop similarly to euploid embryos, monosomy 21 embryos exhibit high rates of developmental arrest, and trisomy 16 embryos display a hypo-proliferation of the trophoblast, the tissue that forms the placenta. Using human trophoblast stem cells, we show that this phenotype can be mechanistically ascribed to increased levels of the cell adhesion protein E-CADHERIN, which lead to premature differentiation and cell cycle arrest. We identify three cases of mosaicism in embryos diagnosed as full aneuploid by pre-implantation genetic testing. Our results present the first detailed analysis of post-implantation development of aneuploid human embryos.

The enigmatic morula: mechanisms of development, cell fate determination, self-correction and implications for ART

BACKGROUND

Assisted reproduction technology offers the opportunity to observe the very early stages of human development. However, due to practical constraints, for decades morphological examination of embryo development has been undertaken at a few isolated time points at the stages of fertilisation (Day 1), cleavage (Day 2-3) and blastocyst (Day 5-6). Rather surprisingly, the morula stage (Day 3-4) has been so far neglected, despite its involvement in crucial cellular processes and developmental decisions.

OBJECTIVE AND RATIONALE

The objective of this review is to collate novel and unsuspected insights into developmental processes occurring during formation of the morula, highlighting the key importance of this stage for a better understanding of preimplantation development and an improvement of ART.

SEARCH METHODS

PubMed was used to search the MEDLINE database for peer-reviewed English-language original articles and reviews concerning the morula stage in mammals. Searches were performed by adopting 'embryo', 'morula', 'compaction', 'cell fate' and 'IVF/assisted reproduction' as main terms, in association with other keywords expressing concepts relevant to the subject (e.g. cell polarity). The most relevant publications, i.e. those concerning major phenomena occurring during formation of the morula in established experimental models and the human species, were assessed and discussed critically.

OUTCOMES

Novel live cell imaging technologies and cell biology studies have extended our understanding of morula formation as a key stage for the development of the blastocyst and determination of the inner cell mass (ICM) and the trophectoderm (TE). Cellular processes, such as dynamic formation of filopodia and cytoskeleton-mediated zippering cell-to-cell interactions, intervene to allow cell compaction (a geometrical requisite essential for development) and formation of the blastocoel, respectively. At the same time, differential orientation of cleavage planes, cell polarity and cortical tensile forces interact and cooperate to position blastomeres either internally or externally, thereby influencing their cellular fate. Recent time lapse microscopy (TLM) observations also suggest that in the human the process of compaction may represent an important checkpoint for embryo viability, through which chromosomally abnormal blastomeres are sensed and eliminated by the embryo.

WIDER IMPLICATIONS

In clinical embryology, the morula stage has been always perceived as a 'black box' in the continuum of preimplantation development. This has dictated its virtual exclusion from mainstream ART procedures. Recent findings described in this review indicate that the morula, and the associated process of compaction, as a crucial stage not only for the formation of the blastocyst, but also for the health of the conceptus. This understanding may open new avenues for innovative approaches to embryo manipulation, assessment and treatment.

Hakin-1, a New Specific Small-Molecule Inhibitor for the E3 Ubiquitin-Ligase Hakai, Inhibits Carcinoma Growth and Progression

The requirement of the E3 ubiquitin-ligase Hakai for the ubiquitination and subsequent degradation of E-cadherin has been associated with enhanced epithelial-to-mesenchymal transition (EMT), tumour progression and carcinoma metastasis. To date, most of the reported EMT-related inhibitors were not developed for anti-EMT purposes, but indirectly affect EMT. On the other hand, E3 ubiquitin-ligase enzymes have recently emerged as promising therapeutic targets, as their specific inhibition would prevent wider side effects. Given this background, a virtual screening was performed to identify novel specific inhibitors of Hakai, targeted against its phosphotyrosine-binding pocket, where phosphorylated-E-cadherin specifically binds. We selected a candidate inhibitor, Hakin-1, which showed an important effect on Hakai-induced ubiquitination. Hakin-1 also inhibited carcinoma growth and tumour progression both in vitro, in colorectal cancer cell lines, and in vivo, in a tumour xenograft mouse model, without apparent systemic toxicity in mice. Our results show for the first time that a small molecule putatively targeting the E3 ubiquitin-ligase Hakai inhibits Hakai-dependent ubiquitination of E-cadherin, having an impact on the EMT process. This represents an important step forward in a future development of an effective therapeutic drug to prevent or inhibit carcinoma tumour progression.

Vibrational stress affects extracellular signal-regulated kinases activation and cytoskeleton structure in human keratinocytes

As the outermost organ, the skin can be damaged following injuries such as wounds and bacterial or viral infections, and such damage should be rapidly restored to defend the body against physical, chemical, and microbial assaults. However, the wound healing process can be delayed or prolonged by health conditions, including diabetes mellitus, venous stasis disease, ischemia, and even stress. In this study, we developed a vibrational cell culture model and investigated the effects of mechanical vibrations on human keratinocytes. The HaCaT cells were exposed to vibrations at a frequency of 45 Hz with accelerations of 0.8g for 2 h per day. The applied mechanical vibration did not affect cell viability or cell proliferation. Cell migratory activity did increase following exposure to vibration, but the change was not statistically significant. The results of immunostaining (F-actin), western blot (ERK1/2), and RT-qPCR (FGF-2, PDGF-B, HB-EGF, TGF-β1, EGFR, and KGFR) analyses demonstrated that the applied vibration resulted in rearrangement of the cytoskeleton, leading to activation of ERK1/2, one of the MAPK signaling pathways, and upregulation of the gene expression levels of HB-EGF and EGFR. The results suggest that mechanical vibration may have wound healing potential and could be used as a mechanical energy-based treatment for enhancing wound healing efficiency.

Genetically encoded X-ray cellular imaging for nanoscale protein localization

Spatial resolution defines the physical limit of microscopes for probing biomolecular localization and interactions in cells. Whereas synchrotron-based X-ray microscopy (XRM) represents a unique approach for imaging a whole cell with nanoscale resolution due to its intrinsic nanoscale resolution and great penetration ability, existing approaches to label biomolecules rely on the use of exogenous tags that are multi-step and error-prone. Here, we repurpose engineered peroxidases as genetically encoded X-ray-sensitive tags (GXET) for site-specific labeling of protein-of-interest in mammalian cells. We find that 3,3^′-diaminobenzidine (DAB) polymers that are in-situ catalytically formed by fusion-expressed peroxidases are visible under XRM. Using this new tag, we imaged the protein location associated with the alteration of a DNA-methylation pathway with an ultra-high resolution of 30 nanometers. Importantly, the excellent energy resolution of XRM enables multicolor imaging using different peroxidase tags. The development of GXET enlightens the way to nanoscopic imaging for biological studies.

EMT Transcription Factors Are Involved in the Altered Cell Adhesion under Simulated Microgravity Effect or Overloading by Regulation of E-cadherin

In order to study the effect of stress changes on cell adhesion, HUVEC, and MCF-7 cells were treated with simulated microgravity effect (SMG) and overloading (OL). Methods: Rotating Wall Vessel (2D-RWVS) bioreactor was used to create different culture conditions. In addition, the alteration of cell adhesion states, adhesion proteins, and relating factors of adhesion molecules under these two conditions were detected using cell adhesion assay, immunofluorescence, western blot, and qRT-PCR technology. Results: The results showed that the adhesion of cells decreased under SMG, while increased under OL. The expressions of integrin β1, paxillin, and E-cadherin under SMG condition were down-regulated as compared to that of the control group showing a time-dependent pattern of the decreasing. However, under OL condition, the expressions of adhesion proteins were up-regulated as compared to that of the control group, with a time-dependent pattern of increasing. EMT transcription factors Snail, twist, and ZEB1 were up-regulated under SMG while down-regulated under OL. Conclusion: Collectively our results indicated that cells could respond to stress changes to regulate the expressions of adhesion proteins and adapt their adhesion state to the altered mechanical environment. The altered cell adhesion in response to the mechanical stress may involve the changed expression of EMT-inducing factors, Snail, Twist, and ZEB1under the SMG/OL conditions.

Epithelial-specific isoforms of protein 4.1R promote adherens junction assembly in maturing epithelia

Epithelial adherens junctions (AJs) and tight junctions (TJs) undergo disassembly and reassembly during morphogenesis and pathological states. The membrane-cytoskeleton interface plays a crucial role in junctional reorganization. Protein 4.1R (4.1R), expressed as a diverse array of spliceoforms, has been implicated in linking the AJ and TJ complex to the cytoskeleton. However, which specific 4.1 isoform(s) participate and the mechanisms involved in junctional stability or remodeling remain unclear. We now describe a role for epithelial-specific isoforms containing exon 17b and excluding exon 16 4.1R (4.1R+17b) in AJs. 4.1R+17b is exclusively co-localized with the AJs. 4.1R+17b binds to the armadillo repeats 1-2 of β-catenin via its membrane-binding domain. This complex is linked to the actin cytoskeleton via a bispecific interaction with an exon 17b-encoded peptide. Exon 17b peptides also promote fodrin-actin complex formation. Expression of 4.1R+17b forms does not disrupt the junctional cytoskeleton and AJs during the steady-state or calcium-dependent AJ reassembly. Overexpression of 4.1R-17b forms, which displace the endogenous 4.1R+17b forms at the AJs, as well as depletion of the 4.1R+17b forms both decrease junctional actin and attenuate the recruitment of spectrin to the AJs and also reduce E-cadherin during the initial junctional formation of the AJ reassembly process. Expressing 4.1R+17b forms in depleted cells rescues junctional localization of actin, spectrin, and E-cadherin assembly at the AJs. Together, our results identify a critical role for 4.1R+17b forms in AJ assembly and offer additional insights into the spectrin-actin-4.1R-based membrane skeleton as an emerging regulator of epithelial integrity and remodeling.

A proteomic study on the protective effect of kaempferol pretreatment against deoxynivalenol-induced intestinal barrier dysfunction in a Caco-2 cell model

Kaempferol pretreatment improved the intestinal barrier dysfunction caused by deoxynivalenol through PKA and MAPK/ERK pathways.

Cell adhesion signals regulate the nuclear receptor activity

Cell adhesion is essential for proper tissue architecture and function in multicellular organisms. Cell adhesion molecules not only maintain tissue integrity but also possess signaling properties that contribute to diverse cellular events such as cell growth, survival, differentiation, polarity, and migration; however, the underlying molecular basis remains poorly defined. Here we identify that the cell adhesion signal initiated by the tight-junction protein claudin-6 (CLDN6) regulates nuclear receptor activity. We show that CLDN6 recruits and activates Src-family kinases (SFKs) in second extracellular domain-dependent and Y196/200-dependent manners, and SFKs in turn phosphorylate CLDN6 at Y196/200. We demonstrate that the CLDN6/SFK/PI3K/AKT axis targets the AKT phosphorylation sites in the retinoic acid receptor γ (RARγ) and the estrogen receptor α (ERα) and stimulates their activities. Interestingly, these phosphorylation motifs are conserved in 14 of 48 members of human nuclear receptors. We propose that a similar link between diverse cell adhesion and nuclear receptor signalings coordinates a wide variety of physiological and pathological processes.

Lens epithelial cells-induced pluripotent stem cells as a model to study epithelial-mesenchymal transition during posterior capsular opacification

The overall goal was to generate an epithelial-mesenchymal transition (EMT) model using lens epithelial cells-induced pluripotent stem cells to elucidate EMT-regulatory factors during posterior capsular opacification (PCO). For this purpose, the mouse lens epithelial cells-derived mesenchymal cells were reprogrammed to induced pluripotent stem cells (iPSC) and differentiated to lens epithelial cells to be used to determine regulatory factors during EMT. Lens epithelial cells from one-month-old C57BL/6 mice were transitioned to mesenchymal cells in culture, and were reprogrammed to iPSC by delivering reprogramming factors in a single polycistronic lentiviral vector (co-expressing four transcription factors, Oct 4, Sox2, Klf4, and Myc). iPSC were differentiated to epithelial cells by a three-step process using noggin, basic fibroblast growth factor (bFGF), bone morphogenetic protein 4 (BMP4) and Wnt-3. At various time points, the cells/clones were immunocytochemically analyzed for epithelial cell markers (Connexin-43 and E-cadherin), mesenchymal cell markers (Alpha-smooth muscle actin), stem cell markers (Sox1, Oct4, SSEA4 and Tra60) and lens-specific epithelial cell markers (αA- and βA3/A1-crystallins).

By increasing the number of genetic transductions, the time needed for generating iPSC from lens mesenchymal cells was reduced, successfully reprogrammed epithelial/mesenchymal cells into iPSC, and retransformed iPSC into lens epithelial cells by the growth factors’ treatment. The epithelial cells could serve as a model system to elucidate regulatory factors involved during EMT to therapeutically stop it.

•

By increasing the number of genetic transductions, reduced the time needed for generating iPSC from lens mesenchymal cells.

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We successfully reprogrammed iPSC, and also differentiated iPSC into lens epithelial cells by the growth factors.

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Our model could elucidate regulatory factors involved in epithelial mesenchymal transition to therapeutically stop it.

Ultrastructure of intestinal mucosa in diarrhea-predominant irritable bowel syndrome

OBJECTIVES

Impaired intestinal barrier function has been demonstrated in the pathophysiology of diarrhea-predominant irritable bowel syndrome (IBS-D). This study aimed to describe the intestinal ultrastructural findings in the intestinal mucosal layer of IBS-D patients.

METHODS

In total, 10 healthy controls and 10 IBS-D patients were analyzed in this study. The mucosa of each patient's rectosigmoid colon was first assessed by confocal laser endomicroscopy (CLE); next, biopsied specimens of these sites were obtained. Intestinal tissues of IBS-D patients and healthy volunteers were examined to observe cellular changes by transmission electron microscopy (TEM).

RESULTS

CLE showed no visible epithelial damage or inflammatory changes in the colonic mucosa of IBS-D compared with healthy volunteers. On transmission electron microscopic examination, patients with IBS-D displayed a larger apical intercellular distance with a higher proportion of dilated (>20 nm) intercellular junctional complexes, which was indicative of impaired mucosal integrity. In addition, microvillus exfoliation, extracellular vesicle as well as increased presence of multivesicular bodies were visible in IBS-D patients. Single epithelial cells appeared necrotic, as characterized by cytoplasmic vacuolization, cytoplasmic swelling, and presence of autolysosome. A significant association between bowel habit, frequency of abdominal pain, and enlarged intercellular distance was found.

CONCLUSION

This study showed ultrastructural alterations in the architecture of intestinal epithelial cells and intercellular junctional complexes in IBS-D patients, potentially representing a pathophysiological mechanism in IBS-D.

The difference in serum proteomes in schizophrenia and bipolar disorder

BACKGROUND

Purpose of study is revealing significant differences in serum proteomes in schizophrenia and bipolar disorder (BD).

RESULTS

Quantitative mass-spectrometry based proteomic analysis was used to quantify proteins in the blood serum samples after the depletion of six major blood proteins. Comparison of proteome profiles of different groups revealed 27 proteins being specific for schizophrenia, and 18 - for BD. Protein set in schizophrenia was mostly associated with immune response, cell communication, cell growth and maintenance, protein metabolism and regulation of nucleic acid metabolism. Protein set in BD was mostly associated with immune response, regulating transport processes across cell membrane and cell communication, development of neurons and oligodendrocytes and cell growth. Concentrations of ankyrin repeat domain-containing protein 12 (ANKRD12) and cadherin 5 in serum samples were determined by ELISA. Significant difference between three groups was revealed in ANKRD12 concentration (p = 0.02), with maximum elevation of ANKRD12 concentration (median level) in schizophrenia followed by BD. Cadherin 5 concentration differed significantly (p = 0.035) between schizophrenic patients with prevailing positive symptoms (4.78 [2.71, 7.12] ng/ml) and those with prevailing negative symptoms (1.86 [0.001, 4.11] ng/ml).

CONCLUSIONS

Our results are presumably useful for discovering the new pathways involved in endogenous psychotic disorders.

Multi-species comparisons of snakes identify coordinated signalling networks underlying post-feeding intestinal regeneration

Several snake species that feed infrequently in nature have evolved the ability to massively upregulate intestinal form and function with each meal. While fasting, these snakes downregulate intestinal form and function, and upon feeding restore intestinal structure and function through major increases in cell growth and proliferation, metabolism and upregulation of digestive function. Previous studies have identified changes in gene expression that underlie this regenerative growth of the python intestine, but the unique features that differentiate this extreme regenerative growth from non-regenerative post-feeding responses exhibited by snakes that feed more frequently remain unclear. Here, we leveraged variation in regenerative capacity across three snake species-two distantly related lineages ( Crotalus and Python) that experience regenerative growth, and one ( Nerodia) that does not-to infer molecular mechanisms underlying intestinal regeneration using transcriptomic and proteomic approaches. Using a comparative approach, we identify a suite of growth, stress response and DNA damage response signalling pathways with inferred activity specifically in regenerating species, and propose a hypothesis model of interactivity between these pathways that may drive regenerative intestinal growth in snakes.