Ezrin is concentrated in the apical microvilli of a wide variety of epithelial cells whereas moesin is found primarily in endothelial cells

Proteomic Analysis of Domestic Cat Blastocysts and Their Secretome Produced in an In Vitro Culture System without the Presence of the Zona Pellucida

Domestic cat blastocysts cultured without the zona pellucida exhibit reduced implantation capacity. However, the protein expression profile has not been evaluated in these embryos. The objective of this study was to evaluate the protein expression profile of domestic cat blastocysts cultured without the zona pellucida. Two experimental groups were generated: (1) domestic cat embryos generated by IVF and cultured in vitro (zona intact, (ZI)) and (2) domestic cat embryos cultured in vitro without the zona pellucida (zona-free (ZF group)). The cleavage, morula, and blastocyst rates were estimated at days 2, 5 and 7, respectively. Day 7 blastocysts and their culture media were subjected to liquid chromatography-tandem mass spectrometry (LC-MS/MS). The UniProt Felis catus database was used to identify the standard proteome. No significant differences were found in the cleavage, morula, or blastocyst rates between the ZI and ZF groups (p > 0.05). Proteomic analysis revealed 22 upregulated and 20 downregulated proteins in the ZF blastocysts. Furthermore, 14 proteins involved in embryo development and implantation were present exclusively in the culture medium of the ZI blastocysts. In conclusion, embryo culture without the zona pellucida did not affect in vitro development, but altered the protein expression profile and release of domestic cat blastocysts.

Etiopathogenesis of Psoriasis: Integration of Proposed Theories

Psoriasis is a chronic inflammatory disease characterized by squamous and erythematous plaques on the skin and the involvement of the immune system. Global prevalence for psoriasis has been reported around 1-3% with a higher incidence in adults and similar proportions between men and women. The risk factors associated with psoriasis are both extrinsic and intrinsic, out of which a polygenic predisposition is a highlight out of the latter. Psoriasis etiology is not yet fully described, but several hypothesis have been proposed: 1) the autoimmunity hypothesis is based on the over-expression of antimicrobial peptides such as LL-37, the proteins ADAMTSL5, K17, and hsp27, or lipids synthesized by the PLA2G4D enzyme, all of which may serve as autoantigens to promote the differentiation of autoreactive lymphocytes T and unleash a chronic inflammatory response; 2) dysbiosis of skin microbiota hypothesis in psoriasis has gained relevance due to the observations of a loss of diversity and the participation of pathogenic bacteria such as Streptococcus spp. or Staphylococcus spp. the fungi Malassezia spp. or Candida spp. and the virus HPV, HCV, or HIV in psoriatic plaques; 3) the oxidative stress hypothesis, the most recent one, describes that the cell injury and the release of proinflammatory mediators and antimicrobial peptides that leads to activate of the Th1/Th17 axis observed in psoriasis is caused by a higher release of reactive oxygen species and the imbalance between oxidant and antioxidant mechanisms. This review aims to describe the mechanisms involved in the three hypotheses on the etiopathogeneses of psoriasis.

Two cases of pediatric primary immunodeficiency caused by a familial moesin(MSN)gene mutation

BACKGROUND

We investigated two brothers who presented with repeated lung infections after 6 months of age. Lymphocytes and neutrophils were significantly decreased, and both had bronchiectasis and emphysema.

OBJECTIVE

We sought to characterize the complete picture of lung injury in some types of primary immunodeficiency disease, followed by verification and analysis.

METHODS

We performed immune function determination, a complete examination of the respiratory system, genetic analysis, and literature research.

RESULTS

The levels of lymphocytes, neutrophils, monocytes, and natural killer cells in the brothers were significantly decreased. The IgM and IgG levels of the older brother were decreased, while the IgM and IgA levels of the younger brother were decreased. Both brothers had bronchial wall erosion with a worm-eaten appearance and decreased lung function. Genetic testing revealed a hemizygous missense mutation (c.511C > T:p.R171W) in exon 5 of the MSN gene, which was inherited from the mother. A literature review showed that the primary immunodeficiency caused by MSN gene mutations is an X-linked recessive genetic disease with four known gene mutation sites, including nonsense and missense mutations. Nonsense mutations result in a higher incidence of autoimmune diseases and a lower degree of immune function impairment. Nonsense mutations closer to the front of the MSN gene may cause more severe disease. Neonatal disease screening can improve the early diagnosis rate, but hematopoietic stem cell transplantation (HSCT) treatment is controversial.

CONCLUSION

The primary immunodeficiency disease caused by MSN gene mutation is an X-linked recessive genetic disease that involves structural and functional damage to the respiratory system, and the worm-eaten appearance of the bronchial wall under endoscopy may be a relatively specific sign. The general manifestations of this disease are recurrent infections from 1 month to 6 months after birth, significantly reduced counts of lymphocytes and neutrophils, and decreased cellular and humoral immune function. Different types of MSN gene mutations and nonsense mutations at different sites have different clinical phenotypes. This study enriches the known spectrum of this disease.

PAR1 regulates sepsis-induced vascular endothelial barrier dysfunction by mediating ERM phosphorylation via the RhoA/ROCK signaling pathway

Sepsis begins with vascular endothelial barrier breakdown and causes widespread organ failure. Protease-activated receptor 1 (PAR1) is an important target for modulating vascular endothelial permeability; however, little research has been undertaken in sepsis, and its putative molecular mechanism remains unknown. The vascular endothelial permeability was examined by detecting FITC-dextran flux. F-actin was examined by immunofluorescence (IF). PAR1, ERM phosphorylation, and RhoA/ROCK signaling pathway expression in lipopolysaccharide (LPS)-stimulated human umbilical vein endothelial cells (HUVECs) line were examined by IF and Western blot. To develop the sepsis model, cecal ligation and puncture (CLP) were conducted. The PAR1 inhibitor SCH79797 was utilized to inhibit PAR1 expression in vivo. Vascular permeability in main organs weres measured by Evans blue dye extravasation. The pathological changes in main organs were examined by HE staining. The expression of PAR1, ERM phosphorylation, and the RhoA/ROCK signaling pathway was examined using IF, immunohistochemical and WB in CLP mice. In vitro, in response to LPS stimulation of HUVECs, PAR1 mediated the phosphorylation of ERM, promoted F-actin rearrangement, and increased endothelial hyperpermeability, all of which were prevented by inhibiting PAR1 or RhoA. Additionally, inhibiting PAR1 expression reduced RhoA and ROCK expression. In vivo, we showed that inhibiting PAR1 expression will reduce ezrin/radixin/moesin (ERM) phosphorylation to relieve vascular endothelial barrier dysfunction and thereby ameliorate multiorgan dysfunction syndrome (MODS) in CLP-induced septic mice. This study revealed that PAR1-mediated phosphorylation of ERM induced endothelial barrier dysfunction, which in turn led to MODS in sepsis, and that the RhoA/ROCK signaling pathway underlay these effects.

Contribution of radixin and ezrin to the maintenance of hepatocytes' excretory function in health and disease

Background & aims

Excretory liver failure is frequently associated with poor prognosis in critically ill patients. It is characterized by the loss of canalicular membrane export pumps at the hepatocyte membrane. The membrane export pump Multidrug resistant-associated protein (MRP) 2 is pivotal in hepatocytes for brushed membrane morphology and transport of various metabolites. In addition, MRP2 anchoring proteins of the Ezrin/Radixin/Moesin (ERM) family are crucial for the correct MRP2 location, integration, and function in different tissues. In hepatocytes, altered ERM signaling is elementary for developing excretory liver failure.

Methods

Polarized human HepaRG cells, primary human hepatocytes, and hepatocyte-specific Ezrin knockout mice are employed to investigate ERM expression and function in health and the bile duct ligation model of obstructive cholestasis.

Results

ERM-scaffolding protein Ezrin has no relevant function in maintaining the canalicular structure in hepatocytes during health and disease.

Conclusions

Homeostasis of the canalicular pole in hepatocytes is maintained exclusively by Radixin but not Ezrin, and Radixin dysfunction promotes cholestasis.

The unique structural and functional characteristics of glomerular endothelial cell fenestrations and their potential as a therapeutic target in kidney disease

Glomerular endothelial cell (GEnC) fenestrations are a critical component of the glomerular filtration barrier. Their unique nondiaphragmed structure is key to their function in glomerular hydraulic permeability, and their aberration in disease can contribute to loss of glomerular filtration function. This review provides a comprehensive update of current understanding of the regulation and biogenesis of fenestrae. We consider diseases in which GEnC fenestration loss is recognized or may play a role and discuss methods with potential to facilitate the study of these critical structures. Literature is drawn from GEnCs as well as other fenestrated cell types such as liver sinusoidal endothelial cells that most closely parallel GEnCs.

Ez-Metastasizing: The Crucial Roles of Ezrin in Metastasis

Ezrin is the cytoskeletal organizer and functions in the modulation of membrane-cytoskeleton interaction, maintenance of cell shape and structure, and regulation of cell-cell adhesion and movement, as well as cell survival. Ezrin plays a critical role in regulating tumor metastasis through interaction with other binding proteins. Notably, Ezrin has been reported to interact with immune cells, allowing tumor cells to escape immune attack in metastasis. Here, we review the main functions of Ezrin, the mechanisms through which it acts, its role in tumor metastasis, and its potential as a therapeutic target.

BioID2 screening identifies KIAA1671 as an EPS8 proximal factor that marks sites of microvillus growth

Microvilli are defining morphological features of the apical surfaces in diverse epithelial tissues. To develop our understanding of microvillus biogenesis, we used a biotin proximity-labeling approach to uncover new molecules enriched near EPS8, a well-studied marker of the microvillus distal tip compartment. Mass spectrometry of biotinylated hits identified KIAA1671, a large (∼200 kDa), disordered, and previously uncharacterized protein. Based on immunofluorescent staining and expression of fluorescent protein-tagged constructs, we found that KIAA1671 localizes to the base of the brush border in native intestinal tissue and polarized epithelial-cell culture models, as well as dynamic actin-rich structures in unpolarized, nonepithelial cell types. Live imaging also revealed that during the early stages of microvillar growth, KIAA1671 colocalizes with EPS8 in diffraction-limited puncta. However, once elongation of the core bundle begins, these two factors separate, with EPS8 tracking the distal end and KIAA1671 remaining behind at the base of the structure. These results suggest that KIAA1671 cooperates with EPS8 and potentially other assembly factors to initiate growth of microvilli on the apical surface. These findings offer new details on how transporting epithelial cells builds the brush border and may inform our understanding of how apical specializations are assembled in other epithelial contexts.

A retrospective analysis of ezrin protein and mRNA expression in breast cancer: Ezrin expression is associated with patient survival and survival of patients with receptor-positive disease

INTRODUCTION

The cytoskeletal protein ezrin is upregulated in many cancer types and is strongly associated with poor patient outcome. While the clinical and prognostic value of ezrin has been previously evaluated in breast cancer, most studies to date have been conducted in smaller cohorts (less than 500 cases) or have focused on specific disease characteristics. The current study is the largest of its kind to evaluate ezrin both at the protein and mRNA levels in early-stage breast cancer patients using the Nottingham (n = 1094) and METABRIC (n = 1980) cohorts, respectively.

RESULTS

High expression of ezrin was significantly associated with larger tumour size (p = 0.027), higher tumour grade (p < 0.001), worse Nottingham Prognostic Index prognostic group (p = 0.011) and HER2-positive status (p = 0.001). High ezrin expression was significantly associated with adverse survival of breast cancer patients (p < 0.001) and remained associated with survival in multivariate Cox-regression analysis (p = 0.018, hazard ratio (HR) = 1.343, 95% confidence interval (CI) = 1.051-1.716) when potentially confounding factors were included. High ezrin expression was significantly associated with adverse survival of patients whose tumours were categorised as receptor (oestrogen receptor (ER), progesterone receptor (PgR) or HER2) positive (p < 0.001) in comparison to those categorised as triple-negative breast cancer (p = 0.889). High expression of ezrin mRNA (VIL2) in the METABRIC cohort was also significantly associated with adverse survival of breast cancer patients (p < 0.001).

CONCLUSION

Retrospective analyses show that ezrin is an independent prognostic marker, with higher expression associated with shortened survival in receptor-positive (ER, PgR or HER2) patients. Ezrin expression is associated with more aggressive disease and may have clinical utility as a biomarker of patient prognosis in early-stage breast cancer.

The morphological and functional diversity of apical microvilli

Sensory neurons use specialized apical processes to perceive external stimuli and monitor internal body conditions. The apical apparatus can include cilia, microvilli, or both, and is adapted for the functions of the particular cell type. Photoreceptors detect light through a large, modified cilium (outer segment), that is supported by a surrounding ring of microvilli-like calyceal processes (CPs). Although first reported 150 years ago, CPs remain poorly understood. As a basis for future study, we therefore conducted a review of existing literature about sensory cell microvilli, which can act either as the primary sensory detector or as support for a cilia-based detector. While all microvilli are finger-like cellular protrusions with an actin core, the processes vary across cell types in size, number, arrangement, dynamics, and function. We summarize the current state of knowledge about CPs and the characteristics of the microvilli found on inner ear hair cells (stereocilia) and cerebral spinal fluid-contacting neurons, with comparisons to the brush border of the intestinal and renal epithelia. The structure, stability, and dynamics of the actin core are regulated by a complement of actin-binding proteins, which includes both common components and unique features when compared across cell types. Further, microvilli are often supported by lateral links, a glycocalyx, and a defined extracellular matrix, each adapted to the function and environment of the cell. Our comparison of microvillar features will inform further research into how CPs support photoreceptor function, and also provide a general basis for investigations into the structure and functions of apical microvilli found on sensory neurons.

Ezrin and Its Phosphorylated Thr567 Form Are Key Regulators of Human Extravillous Trophoblast Motility and Invasion

The protein ezrin has been shown to enhance cancer cell motility and invasion leading to malignant behaviours in solid tumours, but a similar regulatory function in the early physiological reproduction state is, however, much less clear. We speculated that ezrin may play a key role in promoting first-trimester extravillous trophoblast (EVT) migration/invasion. Ezrin, as well as its Thr567 phosphorylation, were found in all trophoblasts studied, whether primary cells or lines. Interestingly, the proteins were seen in a distinct cellular localisation in long, extended protrusions in specific regions of cells. Loss-of-function experiments were carried out in EVT HTR8/SVneo and Swan71, as well as primary cells, using either ezrin siRNAs or the phosphorylation Thr567 inhibitor NSC668394, resulting in significant reductions in both cell motility and cellular invasion, albeit with differences between the cells used. Our analysis further demonstrated that an increase in focal adhesion was, in part, able to explain some of the molecular mechanisms involved. Data collected using human placental sections and protein lysates further showed that ezrin expression was significantly higher during the early stage of placentation and, importantly, clearly seen in the EVT anchoring columns, further supporting the potential role of ezrin in regulating migration and invasion in vivo.

Ezrin immunoexpression in gastric cells of domestic cats infected with Helicobacter spp

The aim of this study was to evaluate de immunoexpression of ezrin in gastric cells of domestic cats infected with Helicobacter spp. and with chronic gastritis. Twenty paraffin-embedded gastric samples were selected based on previous positive results for Helicobacter spp. in the Rapid Urease Test, Warthin-Starry staining and cytology. Haematoxylin-eosin stained sections was done to evaluate inflammatory cell infiltrates. Immunohistochemical analysis was done using anti-Helicobacter pylori and anti-Ezrin antibodies. The analysis of inflammatory infiltrates revealed 8/20 (40%) in score 0, 11/20 (55%) in score 1 and 1/20 (5%) in score 2. The labelling observed in the immunohistochemical analysis using anti-Helicobacter spp. antibody showed no samples with score 0; 4/20 (20%) with score 1; 7/20 35% with score 2 and 9/20 (45%) with score 3. Ezrin overexpression on the cytoplasm of parietal cells was revealed in 18 out of 20 samples (90%). Of these, 10 cases (45%) achieved the score 1; 6 cases (30%) the score 2 and 2 cases (10%) the score 3. On the surface and pit cells there was an increase in Ezrin immnoexpression in 12 out of the 20 samples (60%), of which 8 samples (40%) achieved the score 1 and 4 samples (20%) the score 2. No sample were classified in score 3. Statistically significant differences (p = 0.026) were observed between the inflammatory infiltrate in the gastric mucosa and the immunoexpression of Ezrin in the cytoplasm of parietal cells. It was concluded that ezrin had an increased immunoexpression in the gastric mucosa of cats with chronic gastritis.

Role of Ezrin in Asthma-Related Airway Inflammation and Remodeling

Ezrin is an actin binding protein connecting the cell membrane and the cytoskeleton, which is crucial to maintaining cell morphology, intercellular adhesion, and cytoskeleton remodeling. Asthma involves dysfunction of inflammatory cells, cytokines, and airway structural cells. Recent studies have shown that ezrin, whose function is affected by extensive phosphorylation and protein interactions, is closely associated with asthma, may be a therapeutic target for asthma treatment. In this review, we summarize studies on ezrin and discuss its role in asthma-related airway inflammation and remodeling.

MCC is a centrosomal protein that relocalizes to non-centrosomal apical sites during intestinal cell differentiation

The gene mutated in colorectal cancer (MCC) encodes a coiled-coil protein implicated, as its name suggests, in the pathogenesis of hereditary human colon cancer. To date, however, the contributions of MCC to intestinal homeostasis and disease remain unclear. Here, we examine the subcellular localization of MCC, both at the mRNA and protein levels, in the adult intestinal epithelium. Our findings reveal that Mcc transcripts are restricted to proliferating crypt cells, including Lgr5+ stem cells, where the Mcc protein is distinctly associated with the centrosome. Upon intestinal cellular differentiation, Mcc is redeployed to the apical domain of polarized villus cells where non-centrosomal microtubule organizing centers (ncMTOCs) are positioned. Using intestinal organoids, we show that the shuttling of the Mcc protein depends on phosphorylation by casein kinases 1δ and ε, which are critical modulators of WNT signaling. Together, our findings support a role for MCC in establishing and maintaining the cellular architecture of the intestinal epithelium as a component of both the centrosome and ncMTOC.

A Novel Variant of X-Linked Moesin Gene in a Boy With Inflammatory Bowel Disease Like Disease-A Case Report

Variants in the MSN gene were recently reported as the cause of a primary immunodeficiency disease called X-linked moesin-associated immunodeficiency (X-MAID). Hitherto, only 10 patients were reported worldwide. Here, we report a boy who presented with recurrent high fever, oral ulcers, abdominal pain, and hematochezia for over 2 weeks. His serum inflammatory markers were elevated, and colonoscopy showed multiple colon ulcers and terminal ileum ulcers which resemble colitis caused by inflammatory bowel disease. A novel heterozygous variant c.934G>T(p.Glu312Ter) in the MSN gene was identified using whole exome sequencing (WES) and trio analysis. Intestinal ulcers were almost healed after inducing therapy with steroids and maintenance treatment of anti-TNFα therapy. We summarized the genotype and phenotype of reported X-MAID patients and presented the patient’s unique phenotype in this study. This study also expanded the spectrum of MSN mutation-caused immunodeficiency.

Mitotic Spindle Positioning (MISP) is an actin bundler that selectively stabilizes the rootlets of epithelial microvilli

Microvilli are conserved actin-based surface protrusions that have been repurposed throughout evolution to fulfill diverse cell functions. In the case of transporting epithelia, microvilli are supported by a core of actin filaments bundled in parallel by villin, fimbrin, and espin. Remarkably, microvilli biogenesis persists in mice lacking all three of these factors, suggesting the existence of unknown bundlers. We identified Mitotic Spindle Positioning (MISP) as an actin-binding factor that localizes specifically to the rootlet end of the microvillus. MISP promotes rootlet elongation in cells, and purified MISP exhibits potent filament bundling activity in vitro. MISP-bundled filaments also recruit fimbrin, which further elongates and stabilizes bundles. MISP confinement to the rootlet is enforced by ezrin, which prevents decoration of the membrane-wrapped distal end of the core bundle. These discoveries reveal how epithelial cells optimize apical membrane surface area and offer insight on the remarkable robustness of microvilli biogenesis.

Morales et al. identify Mitotic Spindle Positioning (MISP) as an actin bundler in the rootlets of epithelial microvilli. MISP cooperates with other bundlers, and its rootlet-specific localization is enforced by membrane-actin linker ezrin. These findings illuminate mechanisms that drive the assembly and compartmentalization of actin bundle-supported protrusions.

Could Moesin Be a New Marker for Indicating Progression in Endometrial Cancer?

Aim

This study aims to determine an important parameter in progression from pre-invasive lesions of endometrium to endometrial cancer and also evaluate the effect of this parameter on the progression of endometrial cancer.

Material and Method

In our study,30 patients with normal endometrial tissue (group 1), 56 patients who had endometrial hyperplasia without atypia (group 2), 36 patients who had endometrial hyperplasia with atypia (group 3), and 63 patients with endometrial cancer (group 4) were included. Age, parity, body-mass index, systemic diseases, and tumor markers of patients were evaluated. Expression levels of Ezrin, Radixin, and Moesin proteins were immunohistochemically evaluated in terms of frequency, intensity, and score value.

Results

When we compared hyperplasia cases with or without atypia; frequency, and score value of ezrin expression and frequency, intensity, and score value of moesin expression was significantly higher in patients who had hyperplasia with atypia (p:0.000 p:0.001 p:0.003, p:0.032 p: 0.035 p:0.015 p:0.005, respectively). It was observed that the frequency and score value of moesin expression were significantly higher in patients with endometrial cancer when compared with patients who had hyperplasia with atypia (p:0.003 p:0.045). The frequency of moesin expression was significantly higher in patients who had postoperative mortality (p:0.030 p:0.039).

Conclusion

Increased frequency of moesin expression in the preoperative period in patients with atypical hyperplasia should alert the surgeon in terms of malignancy. If the frequency of moesin expression increases in cases with endometrial cancer, the patient should be followed closely in terms of progression in the postoperative period.

Expression Dynamics of the O-Glycosylated Proteins Recognized by Amaranthus leucocarpus Lectin in T Lymphocytes and Its Relationship With Moesin as an Alternative Mechanism of Cell Activation

T lymphocyte activation begins with antigen/MHC recognition by the TCR/CD3 complex followed by a costimulatory signal provided by CD28. The search for novel costimulatory molecules has been extensive due to their potential use as immunotherapeutic targets. Although some molecules have been identified, they are unable to provide sustainable signaling to allow for proper T cell activation and proliferation. It has been shown that the Amaranthus leucocarpus lectin (ALL) can be used as an in vitro costimulator of CD4+ lymphocytes in the presence of anti-CD3 mAb; this lectin specifically recognizes O-glycans of the Galβ1-3GalNAc-O-Ser/Thr type, including a 70-kDa moesin-like protein that has been suggested as the costimulatory molecule. However, the identity of this molecule has not been confirmed and such costimulation has not been analyzed in CD8+ lymphocytes. We show herein that the expression kinetics of the glycoproteins recognized by ALL (gpALL) is different in CD4+ and CD8+ T cells, unlike moesin expression. Results from IP experiments demonstrate that the previously described 70-kDa moesin-like protein is an O-glycosylated form of moesin (O-moesin) and that in vitro stimulation with anti-CD3 and anti-moesin mAb induces expression of the activation molecules CD69 and CD25, proliferation and IL-2 production as efficiently as cells costimulated with ALL or anti-CD28. Overall, our results demonstrate that O-moesin is expressed in CD4+ and CD8+ T lymphocytes and that moesin provides a new costimulatory activation signal in both T cell subsets.

The ERM protein moesin regulates natural killer cell homeostasis in vivo

Moesin is a member of the ezrin-radixin-moesin (ERM) family of proteins that link plasma membrane proteins with actin filaments in the cell cortex. Hemizygous mutations in the X-linked moesin gene are associated with primary immunodeficiency with T and B cell lymphopenia, which also affects natural killer (NK) cells in most cases. We previously showed that moesin deficiency in mice substantially affects lymphocyte homeostasis, but its impact on NK cells remains unexplored. Here, we found that in moesin-deficient mice, NK cells were decreased in the peripheral blood and bone marrow but increased in the spleen. Analysis of female heterozygous mice showed a selective advantage for moesin-expressing NK cells in the blood. Moesin-deficient NK cells exhibited increased cell death and impaired signaling in response to IL-15, suggesting that moesin regulates NK cell survival through IL-15-mediated signaling. Our findings thus identify moesin as an NK cell homeostasis regulator in vivo.

Modelling and Prevention of Acute Kidney Injury through Ischemia and Reperfusion in a Combined Human Renal Proximal Tubule/Blood Vessel-on-a-Chip

Background

Renal ischemia/reperfusion injury (rIRI) is one of the major causes of AKI. Although animal models are suitable for investigating systemic symptoms of AKI, they are limited in translatability. Human in vitro models are crucial in giving mechanistic insights into rIRI; however, they miss out on crucial aspects such as reperfusion injury and the multitissue aspect of AKI.

Methods

We advanced the current renal proximal tubule-on-a-chip model to a coculture model with a perfused endothelial vessel separated by an extracellular matrix. The coculture was characterized for its three-dimensional structure, protein expression, and response to nephrotoxins. Then, rIRI was captured through control of oxygen levels, nutrient availability, and perfusion flow settings. Injury was quantified through morphologic assessment, caspase-3/7 activation, and cell viability.

Results

The combination of low oxygen, reduced glucose, and interrupted flow was potent to disturb the proximal tubules. This effect was strongly amplified upon reperfusion. Endothelial vessels were less sensitive to the ischemia-reperfusion parameters. Adenosine treatment showed a protective effect on the disruption of the epithelium and on the caspase-3/7 activation.

Conclusions

A human in vitro rIRI model was developed using a coculture of a proximal tubule and blood vessel on-a-chip, which was used to characterize the renoprotective effect of adenosine. The robustness of the model and assays in combination with the throughput of the platform make it ideal to advance pathophysiological research and enable the development of novel therapeutic modalities.

Ezrin Modulates the Cell Surface Expression of Programmed Cell Death Ligand-1 in Human Cervical Adenocarcinoma Cells

Cancer cells employ programmed cell death ligand-1 (PD-L1), an immune checkpoint protein that binds to programmed cell death-1 (PD-1) and is highly expressed in various cancers, including cervical carcinoma, to abolish T-cell-mediated immunosurveillance. Despite a key role of PD-L1 in various cancer cell types, the regulatory mechanism for PD-L1 expression is largely unknown. Understanding this mechanism could provide a novel strategy for cervical cancer therapy. Here, we investigated the influence of ezrin/radixin/moesin (ERM) family scaffold proteins, crosslinking the actin cytoskeleton and certain plasma membrane proteins, on the expression of PD-L1 in HeLa cells. Our results showed that all proteins were expressed at mRNA and protein levels and that all ERM proteins were highly colocalized with PD-L1 in the plasma membrane. Interestingly, immunoprecipitation assay results demonstrated that PD-L1 interacted with ERM as well as actin cytoskeleton proteins. Furthermore, gene silencing of ezrin, but not radixin and moesin, remarkably decreased the protein expression of PD-L1 without affecting its mRNA expression. In conclusion, ezrin may function as a scaffold protein for PD-L1; regulate PD-L1 protein expression, possibly via post-translational modification in HeLa cells; and serve as a potential therapeutic target for cervical cancer, improving the current immune checkpoint blockade therapy.

Ezrin Is a Novel Protein Partner of Aquaporin-5 in Human Salivary Glands and Shows Altered Expression and Cellular Localization in Sjögren's Syndrome

Sjögren’s syndrome (SS) is an exocrinopathy characterized by the hypofunction of salivary glands (SGs). Aquaporin-5 (AQP5); a water channel involved in saliva formation; is aberrantly distributed in SS SG acini and contributes to glandular dysfunction. We aimed to investigate the role of ezrin in AQP5 mislocalization in SS SGs. The AQP5–ezrin interaction was assessed by immunoprecipitation and proteome analysis and by proximity ligation assay in immortalized human SG cells. We demonstrated, for the first time, an interaction between ezrin and AQP5. A model of the complex was derived by computer modeling and in silico docking; suggesting that AQP5 interacts with the ezrin FERM-domain via its C-terminus. The interaction was also investigated in human minor salivary gland (hMSG) acini from SS patients (SICCA-SS); showing that AQP5–ezrin complexes were absent or mislocalized to the basolateral side of SG acini rather than the apical region compared to controls (SICCA-NS). Furthermore, in SICCA-SS hMSG acinar cells, ezrin immunoreactivity was decreased at the acinar apical region and higher at basal or lateral regions, accounting for altered AQP5–ezrin co-localization. Our data reveal that AQP5–ezrin interactions in human SGs could be involved in the regulation of AQP5 trafficking and may contribute to AQP5-altered localization in SS patients

Tracheal motile cilia in mice require CAMSAP3 for formation of central microtubule pair and coordinated beating

Motile cilia of multiciliated epithelial cells undergo synchronized beating to produce fluid flow along the luminal surface of various organs. Each motile cilium consists of an axoneme and a basal body (BB), which are linked by a “transition zone” (TZ). The axoneme exhibits a characteristic 9+2 microtubule arrangement important for ciliary motion, but how this microtubule system is generated is not yet fully understood. Here we show that calmodulin-regulated spectrin-associated protein 3 (CAMSAP3), a protein that can stabilize the minus-end of a microtubule, concentrates at multiple sites of the cilium–BB complex, including the upper region of the TZ or the axonemal basal plate (BP) where the central pair of microtubules (CP) initiates. CAMSAP3 dysfunction resulted in loss of the CP and partial distortion of the BP, as well as the failure of multicilia to undergo synchronized beating. These findings suggest that CAMSAP3 plays pivotal roles in the formation or stabilization of the CP by localizing at the basal region of the axoneme and thereby supports the coordinated motion of multicilia in airway epithelial cells.

Direct visualization of epithelial microvilli biogenesis

Microvilli are actin-bundle-supported surface protrusions that play essential roles in diverse epithelial functions. To develop our understanding of microvilli biogenesis, we used live imaging to directly visualize protrusion growth at early stages of epithelial differentiation. Time-lapse data revealed that specific factors, including epidermal growth factor pathway substrate 8 (EPS8) and insulin-receptor tyrosine kinase substrate (IRTKS) (also known as BAIAP2L1), appear in diffraction-limited puncta at the cell surface and mark future sites of microvillus growth. New core actin bundles elongate from these puncta in parallel with the arrival of ezrin and subsequent plasma membrane encapsulation. In addition to de novo growth, we also observed that new microvilli emerge from pre-existing protrusions. Moreover, we found that nascent microvilli can also collapse, characterized first by loss of membrane wrapping and ezrin enrichment, followed by a sharp decrease in distal tip EPS8 and IRTKS levels, and ultimately disassembly of the core actin bundle itself. These studies are the first to offer a temporally resolved microvillus growth mechanism and highlight factors that participate in this process; they also provide important insights on the growth of apical specializations that will likely apply to diverse epithelial contexts.

High glucose induces Nox4 expression and podocyte apoptosis through the Smad3/ezrin/PKA pathway

Podocytes are the major target in proteinuric kidney diseases such as diabetic nephropathy. The underlying molecular mechanisms by which high glucose (HG) results in podocyte damage remain unclear. This study investigated the regulatory role of Smad3, ezrin, and protein kinase A (PKA) in NADPH oxidase (Nox4) expression, reactive oxidative species (ROS) production, and apoptosis in HG-treated podocytes. A human podocyte cell line was cultured and differentiated, then treated with 30 mM HG. Apoptosis and intracellular ROS levels were assessed using TUNEL and DCF assays, respectively. Expressions of Nox4, phospho-Smad3^Ser423/425, phospho-PKA^Thr197, and phospho-ezrin^Thr567 were evaluated using western blotting. ELISA was used to quantify intracellular cAMP concentration and PKA activity. Knockdown assay was used to inhibit the expressions of Smad3, Nox4, and ezrin by lentiviral shRNA. In HG-treated podocytes, the level of phospho-Smad3^Ser423/425 and phospho-ezrin^Thr567 was increased significantly, which was accompanied by the reduction of cAMP and phospho-PKA^Thr197. HG-induced apoptosis was significantly prevented by the Smad3-inhibitor SIS3 or shRNA-Smad3. In podocytes expressing shRNA-ezrin or shRNA-Nox4, apoptosis was remarkably mitigated following HG treatment. HG-induced upregulation of phospho-ezrin^Thr567 and downregulation of phospho-PKA^Thr197 was significantly prevented by SIS3, shRNA-ezrin or shRNA-Smad3. Forskolin, a PKA activator, significantly inhibited HG-mediated upregulation of Nox4 expression, ROS generation, and apoptosis. Additionally, an increase in the ROS level was prohibited in HG-treated podocytes with the knockdown of Nox4, Smad3, or ezrin. Taken together, our findings provided evidence that Smad3-mediated ezrin activation upregulates Nox4 expression and ROS production, by suppressing PKA activity, which may at least in part contribute to HG-induced podocyte apoptosis.

Summary: The actin-membrane linker protein ezrin-related signaling plays a critical role in podocyte apoptosis through regulation of Nox4 expression and ROS production.

Three-dimensional spheroid culture induces apical-basal polarity and the original characteristics of immortalized human renal proximal tubule epithelial cells

The proximal tubules, which are part of the kidney, maintain blood homeostasis by absorbing amino acids, glucose, water, and ions such as sodium (Na), potassium, and bicarbonate. Proximal tubule dysfunction is associated with the pathogenesis of many kidney diseases. Renal proximal tubular epithelial cells (RPTECs) are responsible for the main functions of the proximal tubules. Therefore, in vitro experiments using RPTECs would greatly enhance our understanding of nephron physiology and pathobiology. It is preferable to use immortalized cell lines, such as human kidney-2 (HK-2) cells, because they are derived from humans and maintain growth indefinitely. However, tissue-specific RPTEC phenotypes, including apical-basal polarization, are frequently lost in conventional two-dimensional culture methods in part due to microenvironmental deficiencies. To overcome this limitation, we developed a three-dimensional (3D) spheroid culture method for HK-2 cells using an extracellular matrix. HK-2 spheroids in 3D culture formed a tubule-like architecture with cellular polarity and showed markedly restored Na transport function. 3D culture of HK-2 cells also increased expression of kidney development-related genes, including WNT9B. Models of human renal tubules using HK-2 spheroids will greatly improve our understanding of the physiology and pathobiology of the kidney.

Stabilization of Endothelial Receptor Arrays by a Polarized Spectrin Cytoskeleton Facilitates Rolling and Adhesion of Leukocytes

Multivalent complexes of endothelial adhesion receptors (e.g., selectins) engage leukocytes to orchestrate their migration to inflamed tissues. Proper anchorage and sufficient density (clustering) of endothelial receptors are required for efficient leukocyte capture and rolling. We demonstrate that a polarized spectrin network dictates the stability of the endothelial cytoskeleton, which is attached to the apical membrane, at least in part, by the abundant transmembrane protein CD44. Single-particle tracking revealed that CD44 undergoes prolonged periods of immobilization as it tethers to the cytoskeleton. The CD44-spectrin "picket fence" alters the behavior of bystander molecules-notably, selectins-curtailing their mobility, inducing their apical accumulation, and favoring their clustering within caveolae. Accordingly, depletion of either spectrin or CD44 virtually eliminated leukocyte rolling and adhesion to the endothelium. Our results indicate that a unique spectrin-based apical cytoskeleton tethered to transmembrane pickets-notably, CD44-is essential for proper extravasation of leukocytes in response to inflammation.

Disruption of the autism-related gene Pak1 causes stereocilia disorganization, hair cell loss, and deafness in mice

Several clinical studies have reported that hearing loss is correlated with autism in children. However, little is known about the underlying mechanism between hearing loss and autism. p21-activated kinases (PAKs) are a family of serine/threonine kinases that can be activated by multiple signaling molecules, particularly the Rho family of small GTPases. Previous studies have shown that Pak1 mutations are associated with autism. In the present study, we take advantage of Pak1 knockout (Pak1^-/-) mice to investigate the role of PAK1 in hearing function. We find that PAK1 is highly expressed in the postnatal mouse cochlea and that PAK1 deficiency leads to hair cell (HC) apoptosis and severe hearing loss. Further investigation indicates that PAK1 deficiency downregulates the phosphorylation of cofilin and ezrin-radixin-moesin and the expression of βII-spectrin, which further decreases the HC synapse density in the basal turn of cochlea and disorganized the HC stereocilia in all three turns of cochlea in Pak1^-/- mice. Overall, our work demonstrates that the autism-related gene Pak1 plays a crucial role in hearing function. As the first candidate gene linking autism and hearing loss, Pak1 may serve as a potential target for the clinical diagnosis of autism-related hearing loss.

Epithelial-mesenchymal transition and cancer stem cell interactions in breast phyllodes tumours: immunohistochemical evaluation of EZH2, EZR, HMGA2, CD24 and CD44 in correlation with outcome analysis

AIM

Phyllodes tumours (PTs) categorised as benign, borderline and malignant, account for 1% of all breast tumours. Histological assessment does not always predict tumour behaviour, hindering determination of the clinical course and management.Epithelial-mesenchymal transition (EMT) is an important process during embryogenesis. Dysregulation of EMT causes loss of cell polarity, decreased intercellular adhesion, increased motility and invasiveness, promoting tumour progression. Similarly, cancer stem cells (CSCs) promote tumour growth, resistance and recurrence. The aim of this study is to evaluate expression of CSC markers; enhancer of zeste homolog 2 (EZH2), CD24 and CD44 and EMT associated proteins; ezrin (EZR) and high-mobility group AT-hook 2 (HMGA2) in PTs.

METHOD

Uing tissue microarray sections, immunohistochemistry was performed on 360 PTs. Epithelial and stromal expressions of EZH2, EZR, HMGA2, CD24 and CD44 were evaluated to assess their impact on disease progression and behaviour in correlation with clinicopathological parameters.

RESULTS

Stromal expression of EZH2, EZR and HMGA2 was observed in 73 (20.3%), 53 (14.7%) and 28 (7.8%) of tumours, epithelial expression in 121 (35.9%), 3 (0.8%) and 351 (97.5%) tumours, respectively. CD24 and CD44 staining was absent in both components.

CONCLUSION

Expression of biomarkers correlated significantly with aggressive tumour traits such as stromal hypercellularity, atypia, mitoses and permeative tumour borders.Stromal expression of EZH2 and EZR shortened disease-free survival and overall survival; HMGA2 expression did not alter patient survival. EZH2 and EZR may thus be useful in predicting PT behaviour.

eys +/- ; lrp5 +/- Zebrafish Reveals Lrp5 Can Be the Receptor of Retinol in the Visual Cycle

Vision is essential for vertebrates including humans. Sustained vision is accomplished by retinoid metabolism, the “visual cycle,” where all-trans retinol (atROL) is incorporated into the retinal pigment epithelium (RPE) from photoreceptors presumably through decade-long missing receptor(s). Here, we show that the LDL-related receptor-5 (Lrp5) protein is linked to the retinol binding protein 1a (Rbp1a), the transporter of atROL in the visual cycle, by generating and analyzing the digenic eyes shut homolog^+/-; lrp5^+/− zebrafish, the same form of gene defect detected in a human case of inherited retinal degeneration. Global gene expression analysis followed by genetic study clarified that rbp1a played a role downstream of lrp5. Rbp1a protein was colocalized with Lrp5 protein at microvilli of RPE cells. Furthermore, Rbp1a directly bound to the C-terminal intracellular region of Lrp5 in vitro. Collectively, these results strongly suggest that Lrp5 is a potent candidate of the receptor of atROL in the visual cycle.

•

eys^+/-; lrp5^+/− zebrafish showed mild photoreceptor degeneration

•

Microarray analysis identified dramatical decrease of rbp1a expression

•

Rbp1a protein was colocalized with Lrp5 protein at the microvilli of the RPE

•

Rbp1a directly bound to the C-terminal intracellular region of Lrp5 in vitro

The ERM Complex: A New Player Involved in Diabetes-induced Vascular Leakage

BACKGROUND

Microvascular complications remain an important cause of morbidity in diabetic patients, and they are associated with a significant economic burden for healthcare systems. Vascular leakage is one of the earlier hallmarks in diabetic microvascular complications. Ezrin, Radixin and Moesin (ERM) proteins have recently been involved in vascular dysfunction under the effect of molecular mediators of diabetes complications. In this review, we will present the available evidence regarding the role of these proteins in vascular leakage and their putative implication in diabetic microvascular complications.

METHODS AND RESULTS

A comprehensive literature search of the electronic MEDLINE database was performed between November 2017 and January 2018. As a result, 36 articles have been reviewed and discussed.

DISCUSSION

ERM proteins are cytoskeleton-membrane linkers, and when activated in endothelial cells are able to induce cytoskeleton reorganization in stress fibers leading to the disassembly of focal adhesions and the formation of paracellular gaps which result in an increase of vascular permeability. The activation of these proteins is induced by mediators involved in diabetic complications such as PKC activation, TNF-α, AGEs and oxidative stress. In conclusion, ERMs play an essential role in endothelium homeostasis and can be envisaged as a new therapeutic molecular target for preventing or arresting diabetes-induced vascular leakage.

A cryptic sequence targets the adhesion complex scaffold ANKS4B to apical microvilli to promote enterocyte brush border assembly

Nutrient-transporting enterocytes interact with their luminal environment using a densely packed collection of apical microvilli known as the brush border. Assembly of the brush border is controlled by the intermicrovillar adhesion complex (IMAC), a protocadherin-based complex found at the tips of brush border microvilli that mediates adhesion between neighboring protrusions. ANKS4B is known to be an essential scaffold within the IMAC, although its functional properties have not been thoroughly characterized. We report here that ANKS4B is directed to the brush border using a noncanonical apical targeting sequence that maps to a previously unannotated region of the scaffold. When expressed on its own, this sequence targeted to microvilli in the absence of any direct interaction with the other IMAC components. Sequence analysis revealed a coiled-coil motif and a putative membrane-binding basic-hydrophobic repeat sequence within this targeting region, both of which were required for the scaffold to target and mediate brush border assembly. Size-exclusion chromatography of the isolated targeting sequence coupled with in vitro brush border binding assays suggests that it functions as an oligomer. We further show that the corresponding sequence found in the closest homolog of ANKS4B, the scaffold USH1G that operates in sensory epithelia as part of the Usher complex, lacks the inherent ability to target to microvilli. This study further defines the underlying mechanism of how ANKS4B targets to the apical domain of enterocytes to drive brush border assembly and identifies a point of functional divergence between the ankyrin repeat-based scaffolds found in the IMAC and Usher complex.

Flow-cytometric microglial sorting coupled with quantitative proteomics identifies moesin as a highly-abundant microglial protein with relevance to Alzheimer's disease

BACKGROUND

Proteomic characterization of microglia provides the most proximate assessment of functionally relevant molecular mechanisms of neuroinflammation. However, microglial proteomics studies have been limited by low cellular yield and contamination by non-microglial proteins using existing enrichment strategies.

METHODS

We coupled magnetic-activated cell sorting (MACS) and fluorescence activated cell sorting (FACS) of microglia with tandem mass tag-mass spectrometry (TMT-MS) to obtain a highly-pure microglial proteome and identified a core set of highly-abundant microglial proteins in adult mouse brain. We interrogated existing human proteomic data for Alzheimer's disease (AD) relevance of highly-abundant microglial proteins and performed immuno-histochemical and in-vitro validation studies.

RESULTS

Quantitative multiplexed proteomics by TMT-MS of CD11b + MACS-enriched (N = 5 mice) and FACS-isolated (N = 5 mice), from adult wild-type mice, identified 1791 proteins. A total of 203 proteins were highly abundant in both datasets, representing a core-set of highly abundant microglial proteins. In addition, we found 953 differentially enriched proteins comparing MACS and FACS-based approaches, indicating significant differences between both strategies. The FACS-isolated microglia proteome was enriched with cytosolic, endoplasmic reticulum, and ribosomal proteins involved in protein metabolism and immune system functions, as well as an abundance of canonical microglial proteins. Conversely, the MACS-enriched microglia proteome was enriched with mitochondrial and synaptic proteins and higher abundance of neuronal, oligodendrocytic and astrocytic proteins. From the 203 consensus microglial proteins with high abundance in both datasets, we confirmed microglial expression of moesin (Msn) in wild-type and 5xFAD mouse brains as well as in human AD brains. Msn expression is nearly exclusively found in microglia that surround Aβ plaques in 5xFAD brains. In in-vitro primary microglial studies, Msn silencing by siRNA decreased Aβ phagocytosis and increased lipopolysaccharide-induced production of the pro-inflammatory cytokine, tumor necrosis factor (TNF). In network analysis of human brain proteomic data, Msn was a hub protein of an inflammatory co-expression module positively associated with AD neuropathological features and cognitive dysfunction.

CONCLUSIONS

Using FACS coupled with TMT-MS as the method of choice for microglial proteomics, we define a core set of highly-abundant adult microglial proteins. Among these, we validate Msn as highly-abundant in plaque-associated microglia with relevance to human AD.

A pharmaceutical industry perspective on microphysiological kidney systems for evaluation of safety for new therapies

The human kidney contains approximately one million nephrons. As the functional unit of the kidney, the nephron affords an opportunity to approximate the kidney at a microphysiological scale. Recent emergence of physiologically accurate human tissue models has radically advanced the possibilities of mimicking organ biology and multi-organ combinations in vitro. Anatomically, the nephron is one of the most complex, sequentially integrated microfluidic units in the body making the miniaturized microfluidic systems excellent candidates for capturing the kidney biology in vitro. While these models are promising, there are a number of considerations for practical implementation into a drug development paradigm. Opportunities for pharmaceutical industry applications of new MPS models often start with drug safety testing. As such, the intent of this article is to focus on safety and ADME applications. This article reviews biological functions of the kidney and options for characterizing known roles in nephrotoxicity. The concept of "context-of-use" is introduced as a framework for describing and verifying the specific features of an MPS platform for use in drug development. Overall, we present a perspective on key attributes of microphysiological kidney models, which the pharmaceutical industry could leverage to improve confident safety and ADME evaluations of experimental therapies.

Membrane Tension and the Role of Ezrin During Phagocytosis

During phagocytosis, there is an apparent expansion of the plasma membrane to accommodate the target within a phagosome. This is accompanied (or driven by) a change in membrane tension. It is proposed that the wrinkled topography of the phagocyte surface, by un-wrinkling, provides the additional available membrane and that this explains the changes in membrane tension. There is no agreement as to the mechanism by which unfolding of cell surface wrinkles occurs during phagocytosis, but there is a good case building for the involvement of the actin-plasma membrane crosslinking protein ezrin. Not only have direct measurements of membrane tension strongly implicated ezrin as the key component in establishing membrane tension, but the cortical location of ezrin changes at the phagocytic cup, suggesting that it is locally signalled. This chapter therefore attempts to synthesise our current state of knowledge about ezrin and membrane tension with phagocytosis to provide a coherent hypothesis.

High-Throughput Single Cell Proteomics Enabled by Multiplex Isobaric Labeling in a Nanodroplet Sample Preparation Platform

Effective extension of mass spectrometry-based proteomics to single cells remains challenging. Herein we combined microfluidic nanodroplet technology with tandem mass tag (TMT) isobaric labeling to significantly improve analysis throughput and proteome coverage for single mammalian cells. Isobaric labeling facilitated multiplex analysis of single cell-sized protein quantities to a depth of ∼1 600 proteins with a median CV of 10.9% and correlation coefficient of 0.98. To demonstrate in-depth high throughput single cell analysis, the platform was applied to measure protein expression in 72 single cells from three murine cell populations (epithelial, immune, and endothelial cells) in <2 days instrument time with over 2 300 proteins identified. Principal component analysis grouped the single cells into three distinct populations based on protein expression with each population characterized by well-known cell-type specific markers. Our platform enables high throughput and unbiased characterization of single cell heterogeneity at the proteome level.

Perspectives for Ezrin and Radixin in Astrocytes: Kinases, Functions and Pathology

Astrocytes are increasingly perceived as active partners in physiological brain function and behaviour. The structural correlations of the glia–synaptic interaction are the peripheral astrocyte processes (PAPs), where ezrin and radixin, the two astrocytic members of the ezrin-radixin-moesin (ERM) family of proteins are preferentially localised. While the molecular mechanisms of ERM (in)activation appear universal, at least in mammalian cells, and have been studied in great detail, the actual ezrin and radixin kinases, phosphatases and binding partners appear cell type specific and may be multiplexed within a cell. In astrocytes, ezrin is involved in process motility, which can be stimulated by the neurotransmitter glutamate, through activation of the glial metabotropic glutamate receptors (mGluRs) 3 or 5. However, it has remained open how this mGluR stimulus is transduced to ezrin activation. Knowing upstream signals of ezrin activation, ezrin kinase(s), and membrane-bound binding partners of ezrin in astrocytes might open new approaches to the glial role in brain function. Ezrin has also been implicated in invasive behaviour of astrocytomas, and glial activation. Here, we review data pertaining to potential molecular interaction partners of ezrin in astrocytes, with a focus on PKC and GRK2, and in gliomas and other diseases, to stimulate further research on their potential roles in glia-synaptic physiology and pathology.

Human ESC-derived retinal epithelial cell sheets potentiate rescue of photoreceptor cell loss in rats with retinal degeneration

Replacing defective retinal pigment epithelial (RPE) cells with those derived from human embryonic stem cells (hESCs) or human-induced pluripotent stem cells (hiPSCs) is a potential strategy for treating retinal degenerative diseases. Early clinical trials have demonstrated that hESC-derived or hiPSC-derived RPE cells can be delivered safely as a suspension to the human eye. The next step is transplantation of hESC/hiPSC-derived RPE cells as cell sheets that are more physiological. We have developed a tissue-engineered product consisting of hESC-derived RPE cells grown as sheets on human amniotic membrane as a biocompatible substrate. We established a surgical approach to engraft this tissue-engineered product into the subretinal space of the eyes of rats with photoreceptor cell loss. We show that transplantation of the hESC-RPE cell sheets grown on a human amniotic membrane scaffold resulted in rescue of photoreceptor cell death and improved visual acuity in rats with retinal degeneration compared to hESC-RPE cells injected as a cell suspension. These results suggest that tissue-engineered hESC-RPE cell sheets produced under good manufacturing practice conditions may be a useful approach for treating diseases of retinal degeneration.

Mechanisms and Regulation of Intestinal Phosphate Absorption

States of hypo- and hyperphosphatemia have deleterious consequences including rickets/osteomalacia and renal/cardiovascular disease, respectively. Therefore, the maintenance of appropriate plasma levels of phosphate is an essential requirement for health. This control is executed by the collaborative action of intestine and kidney whose capacities to (re)absorb phosphate are regulated by a number of hormonal and metabolic factors, among them parathyroid hormone, fibroblast growth factor 23, 1,25(OH)₂ vitamin D₃ , and dietary phosphate. The molecular mechanisms responsible for the transepithelial transport of phosphate across enterocytes are only partially understood. Indeed, whereas renal reabsorption entirely relies on well-characterized active transport mechanisms of phosphate across the renal proximal epithelia, intestinal absorption proceeds via active and passive mechanisms, with the molecular identity of the passive component still unknown. The active absorption of phosphate depends mostly on the activity and expression of the sodium-dependent phosphate cotransporter NaPi-IIb (SLC34A2), which is highly regulated by many of the factors, mentioned earlier. Physiologically, the contribution of NaPi-IIb to the maintenance of phosphate balance appears to be mostly relevant during periods of low phosphate availability. Therefore, its role in individuals living in industrialized societies with high phosphate intake is probably less relevant. Importantly, small increases in plasma phosphate, even within normal range, associate with higher risk of cardiovascular disease. Therefore, therapeutic approaches to treat hyperphosphatemia, including dietary phosphate restriction and phosphate binders, aim at reducing intestinal absorption. Here we review the current state of research in the field. © 2017 American Physiological Society. Compr Physiol 8:1065-1090, 2018.

HopQ impacts the integrin α5β1-independent NF-κB activation by Helicobacter pylori in CEACAM expressing cells

Helicobacter pylori infection persists in more than half of the world's population and represents a risk factor for peptic ulcer disease and gastric cancer. Virulent strains of H. pylori carry a cag pathogenicity island (cagPAI), which encodes a type IV secretion system (T4SS) with the capability to inject the effector protein cytotoxin-associated gene A (CagA) into eukaryotic cells. Colonisation of the gastric epithelium by H. pylori provokes direct activation of the proinflammatory and survival factor nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB). We investigated the impact of host cell receptor integrin α5β1 and the bacterial adhesin HopQ on the NF-κB activation. We found that H. pylori induced early T4SS-dependent, but CagA-independent canonical NF-κB signalling in polarized, apical infected NCI-N87 cells. Integrin-dependent CagA translocation was hardly detectable, as integrin β1 was sparsely located at the apical surface of polarized NCI-N87 cells. Knockdown experiments indicated that integrin α5β1 and integrin linked kinase (ILK) were dispensable for NF-κB activation in H. pylori infection. Thus, there exists no common mechanism, which mediates integrin α5β1-dependent H. pylori-triggered CagA translocation and the activation of NF-κB. Further, we report that H. pylori adhesin HopQ, which binds to a specific subset of carcinoembryonic antigen-related cell adhesion molecules (CEACAMs), promotes canonical NF-κB activation in AGS and NCI-N87 cells, but not in HeLa cells, which are devoid of these CEACAMs. Noteworthy, these effects were not mediated by reduced adhesion, indicating additional functions of HopQ.

NHERF1 Between Promises and Hopes: Overview on Cancer and Prospective Openings

Na+/H+ exchanger regulatory factor 1 (NHERF1) is a scaffold protein, with two tandem PDZ domains and a carboxyl-terminal ezrin-binding (EB) region. This particular sticky structure is responsible for its interaction with different molecules to form multi-complexes that have a pivotal role in a lot of diseases. In particular, its involvement during carcinogenesis and cancer progression has been deeply analyzed in different tumors. The role of NHERF1 is not unique in cancer; its activity is connected to its subcellular localization. The literature data suggest that NHERF1 could be a new prognostic/predictive biomarker from breast cancer to hematological cancers. Furthermore, the high potential of this molecule as therapeutical target in different carcinomas is a new challenge for precision medicine. These evidences are part of a future view to improving patient clinical management, which should allow different tumor phenotypes to be treated with tailored therapies. This article reviews the biology of NHERF1, its engagement in different signal pathways and its involvement in different cancers, with a specific focus on breast cancer. It also considers NHERF1 potential role during inflammation related to most human cancers, designating new perspectives in the study of this "Janus-like" protein.

Loss of ezrin expression reduced the susceptibility to the glomerular injury in mice

Ezrin is highly expressed in glomerular podocytes and is reported to form a multi-protein complex with scaffold protein Na⁺/H⁺ exchanger regulatory factor 2 (NHERF2) and podocalyxin, a major sialoprotein. Podocalyxin-knockout mice died within 24 h of birth with anuric renal failure, whereas NHERF2-knockout mice show no apparent changes in the glomerular functions. However, the physiological roles of ezrin in glomerular podocytes remain unclear. Here, we investigated the importance of ezrin in the regulation of glomerular podocyte function using ezrin-knockdown mice (Vil2 ^kd/kd ). The Vil2 ^kd/kd mice did not exhibit apparent glomerular dysfunction, morphological defects or abnormal localisation of podocalyxin and NHERF2 in podocytes. Thus, we investigated the influence of ezrin defects on Rho-GTPase activity, as ezrin interacts with the Rho-GTPase dissociation inhibitor (Rho-GDI), which plays a key role in the regulation of podocyte actin organisation. In Vil2 ^kd/kd glomeruli, Rac1 activity was significantly reduced compared to wildtype (WT) glomeruli at baseline. Furthermore, Vil2 ^kd/kd mice showed reduced susceptibility to glomerular injury. In WT glomeruli, Rac1 activity was enhanced in nephrotic conditions, but remained at baseline levels in Vil2 ^kd/kd glomeruli, suggesting that loss of ezrin protects podocytes from injury-induced morphological changes by suppressing Rac1 activation.

Moesin is involved in polarity maintenance and cortical remodeling during asymmetric cell division

An intact actomyosin network is essential for anchoring polarity proteins to the cell cortex and maintaining cell size asymmetry during asymmetric cell division of Drosophila neuroblasts (NBs). However, the mechanisms that control changes in actomyosin dynamics during asymmetric cell division remain unclear. We find that the actin-binding protein, Moesin, is essential for NB proliferation and mitotic progression in the developing brain. During metaphase, phosphorylated Moesin (p-Moesin) is enriched at the apical cortex, and loss of Moesin leads to defects in apical polarity maintenance and cortical stability. This asymmetric distribution of p-Moesin is determined by components of the apical polarity complex and Slik kinase. During later stages of mitosis, p-Moesin localization shifts more basally, contributing to asymmetric cortical extension and myosin basal furrow positioning. Our findings reveal Moesin as a novel apical polarity protein that drives cortical remodeling of dividing NBs, which is essential for polarity maintenance and initial establishment of cell size asymmetry.

Distinct Ezrin Truncations Differentiate Metastases in Sentinel Lymph Nodes from Unaffected Lymph Node Tissues, from Primary Breast Tumors, and from Healthy Glandular Breast Tissues

BACKGROUND

Lymph node metastasis status is a prognostic factor for further lymph node involvement and for patient survival in breast cancer patients. Frozen section analysis of lymph nodes is a reliable method for detection of macro-metastases. However, this method is far less effective in detecting micro-metastases, requesting improved diagnostic procedures.

METHODS

We investigated expression and truncation of ezrin in (i) sentinel lymph node metastases, (ii) unaffected axillary lymph nodes, (iii) primary breast tumors, and (iv) healthy glandular breast tissues using 2D gel electrophoresis, SDS-PAGE, and mass spectrometry in addition to Western blotting.

RESULTS

Full-length ezrin (E1; amino acids 1-586) is present in all four investigated tissues. Two truncated ezrin forms, one missing about the first hundred amino acids (E2a) and the other lacking about 150 C-terminal amino acids (E2b) were detectable in primary tumor tissues and in sentinel lymph node metastases but not in glandular tissues. Strikingly, an ezrin truncation (E3) which consists approximately of amino acids 238-586 was found strongly expressed in all sentinel lymph node metastases. Moreover, an N-terminal ezrin fragment (E4) that consists approximately of amino acids 1-273 was identified in sentinel lymph node metastases as well.

CONCLUSIONS

We show for the first time the existence of tissue-dependent specific ezrin truncations. The distinguished strong Western blot staining of ezrin E3 in sentinel lymph node metastases underlines its capability to substantiate the occurrence of lymph node (micro)metastases in breast cancer patients.

Neural Stem Cell Death Mechanisms Induced by Amyloid Beta

Background and Purpose

Amyloid beta (Aβ) is the main component of amyloid plaques, which are deposited in the brains of patients with Alzheimer's disease (AD). Biochemical and animal studies support the central role of Aβ in AD pathogenesis. Despite several investigations focused on the pathogenic mechanisms of Aβ, it is still unclear how Aβ accumulates in the central nervous system and subsequently initiates the disease at the cellular level. In this study, we investigated the pathogenic mechanisms of Aβ using proteomics and antibody microarrays.

Methods

To evaluate the effect of Aβ on neural stem cells (NSCs), we treated primary cultured cortical NSCs with several doses of Aβ for 48 h. A 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide assay, trypan blue staining, and bromodeoxyuridine cell proliferation assay were performed. We detected several intracellular proteins that may be associated with Aβ by proteomics and Western blotting analysis.

Results

Various viability tests showed that Aβ decreased NSCs viability and cell proliferation in a concentration-dependent manner. Aβ treatment significantly decreased lactate dehydrogenase B, high-mobility group box 1, aldolase C, Ezrin, and survival signals including phosphorylated phosphoinositide 3-kinase, Akt, and glycogen synthase kinase-3β.

Conclusions

These results suggest that several factors determined by proteomics and Western blot hold the clue to Aβ pathogenesis. Further studies are required to investigate the role of these factors.

Ezrin directly interacts with AQP2 and promotes its endocytosis

The water channel aquaporin-2 (AQP2) is a major regulator of water homeostasis in response to vasopressin (VP). Dynamic trafficking of AQP2 relies on its close interaction with trafficking machinery proteins and the actin cytoskeleton. Here, we report the identification of ezrin, an actin-binding protein from the ezrin/radixin/moesin (ERM) family as an AQP2-interacting protein. Ezrin was first detected in a co-immunoprecipitation (co-IP) complex using an anti-AQP2 antibody in a proteomic analysis. Immunofluorescence staining revealed the co-expression of ezrin and AQP2 in collecting duct principal cells, and VP treatment caused redistribution of both proteins to the apical membrane. The ezrin-AQP2 interaction was confirmed by co-IP experiments with an anti-ezrin antibody, and by pulldown assays using purified full-length and FERM domain-containing recombinant ezrin. By using purified recombinant proteins, we showed that ezrin directly interacts with AQP2 C-terminus through its N-terminal FERM domain. Knocking down ezrin expression with shRNA resulted in increased membrane accumulation of AQP2 and reduced AQP2 endocytosis. Therefore, through direct interaction with AQP2, ezrin facilitates AQP2 endocytosis, thus linking the dynamic actin cytoskeleton network with AQP2 trafficking.