E-cadherin bridges cell polarity and spindle orientation to ensure prostate epithelial integrity and prevent carcinogenesis in vivo

Cell division-dependent dissemination following E-cadherin loss underlies initiation of diffuse-type gastric cancer

Loss of the cell-cell adhesion protein E-cadherin underlies the development of diffuse-type gastric cancer (DGC), which is characterized by the gradual accumulation of tumor cells originating from the gastric epithelium in the surrounding stroma. How E-cadherin deficiency drives DGC formation remains elusive. Therefore, we investigated the consequences of E-cadherin loss on gastric epithelial organization utilizing a human gastric organoid model and histological analyses of early-stage DGC lesions. E-cadherin depletion from gastric organoids recapitulates DGC initiation, with progressive loss of a single-layered architecture and detachment of individual cells. We found that E-cadherin deficiency in gastric epithelia does not lead to a general loss of epithelial cohesion but disrupts the spindle orientation machinery. This leads to a loss of planar cell division orientation and, consequently, daughter cells are positioned outside of the gastric epithelial layer. Although basally delaminated cells fail to detach and instead reintegrate into the epithelium, apically mispositioned daughter cells can trigger the gradual loss of the single-layered epithelial architecture. This impaired architecture hampers reintegration of mispositioned daughter cells and enables basally delaminated cells to disseminate into the surrounding matrix. Taken together, our findings describe how E-cadherin deficiency disrupts gastric epithelial architecture through displacement of dividing cells and provide new insights in the onset of DGC. © 2024 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Interplay between the plasma membrane and cell-cell adhesion maintains epithelial identity for correct polarised cell divisions

Polarised epithelial cell divisions represent a fundamental mechanism for tissue maintenance and morphogenesis. Morphological and mechanical changes in the plasma membrane influence the organisation and crosstalk of microtubules and actin at the cell cortex, thereby regulating the mitotic spindle machinery and chromosome segregation. Yet, the precise mechanisms linking plasma membrane remodelling to cell polarity and cortical cytoskeleton dynamics to ensure accurate execution of mitosis in mammalian epithelial cells remain poorly understood. Here, we manipulated the density of mammary epithelial cells in culture, which led to several mitotic defects. Perturbation of cell-cell adhesion formation impairs the dynamics of the plasma membrane, affecting the shape and size of mitotic cells and resulting in defects in mitotic progression and the generation of daughter cells with aberrant architecture. In these conditions, F- actin-astral microtubule crosstalk is impaired, leading to mitotic spindle misassembly and misorientation, which in turn contributes to chromosome mis-segregation. Mechanistically, we identify S100 Ca2+-binding protein A11 (S100A11) as a key membrane-associated regulator that forms a complex with E-cadherin (CDH1) and the leucine-glycine-asparagine repeat protein LGN (also known as GPSM2) to coordinate plasma membrane remodelling with E-cadherin-mediated cell adhesion and LGN-dependent mitotic spindle machinery. Thus, plasma membrane-mediated maintenance of mammalian epithelial cell identity is crucial for correct execution of polarised cell divisions, genome maintenance and safeguarding tissue integrity.

Stroma-specific gene expression signature identifies prostate cancer subtype with high recurrence risk

Current prognostic tools cannot clearly distinguish indolent and aggressive prostate cancer (PC). We hypothesized that analyzing individual contributions of epithelial and stromal components in localized PC (LPC) could improve risk stratification, as stromal subtypes may have been overlooked due to the emphasis on malignant epithelial cells. Hence, we derived molecular subtypes of PC using gene expression analysis of LPC samples from prostatectomy patients (cohort 1, n = 127) and validated these subtypes in two independent prostatectomy cohorts (cohort 2, n = 406, cohort 3, n = 126). Stroma and epithelium-specific signatures were established from laser-capture microdissection data and non-negative matrix factorization was used to identify subtypes based on these signatures. Subtypes were functionally characterized by gene set and cell type enrichment analyses, and survival analysis was conducted. Three epithelial (E1-E3) and three stromal (S1-S3) PC subtypes were identified. While subtyping based on epithelial signatures showed inconsistent associations to biochemical recurrence (BCR), subtyping by stromal signatures was significantly associated with BCR in all three cohorts, with subtype S3 indicating high BCR risk. Subtype S3 exhibited distinct features, including significantly decreased cell-polarity and myogenesis, significantly increased infiltration of M2-polarized macrophages and CD8 + T-cells compared to subtype S1. For patients clinically classified as CAPRA-S intermediate risk, S3 improved prediction of BCR. This study demonstrates the potential of stromal signatures in identification of clinically relevant PC subtypes, and further indicated that stromal characterization may enhance risk stratification in LPC and may be particularly promising in cases with high prognostic ambiguity based on clinical parameters.

Scribble, Lgl1, and myosin IIA interact with α-/β-catenin to maintain epithelial junction integrity

E-cadherin-catenin complex together with the cytoskeleton, builds the core of Adherens junctions (AJs). It has been reported that Scribble stabilizes the coupling of E-cadherin with catenins promoting epithelial cell adhesion, but the mechanism remains unknown. We show that Scribble, Lgl1, and NMII-A reside in a complex with E-cadherin-catenin complex. Depletion of either Scribble or Lgl1 disrupts the localization of E-cadherin-catenin complex to AJs. aPKCζ phosphorylation of Lgl1 regulates AJ localization of Lgl1 and E-cadherin-catenin complexes. Both Scribble and Lgl1 regulate the activation and recruitment of NMII-A at AJs. Finally, Scribble and Lgl1 are downregulated by TGFβ-induced EMT, and their re-expression during EMT impedes its progression. Our results provide insight into the mechanism regulating AJ integrity by Scribble, Lgl1, and NMII-A.

Combined loss of CDH1 and downstream regulatory sequences drive early-onset diffuse gastric cancer and increase penetrance of hereditary diffuse gastric cancer

BACKGROUND

Germline CDH1 pathogenic or likely pathogenic variants cause hereditary diffuse gastric cancer (HDGC). Once a genetic cause is identified, stomachs' and breasts' surveillance and/or prophylactic surgery is offered to asymptomatic CDH1 carriers, which is life-saving. Herein, we characterized an inherited mechanism responsible for extremely early-onset gastric cancer and atypical HDGC high penetrance.

METHODS

Whole-exome sequencing (WES) re-analysis was performed in an unsolved HDGC family. Accessible chromatin and CDH1 promoter interactors were evaluated in normal stomach by ATAC-seq and 4C-seq, and functional analysis was performed using CRISPR-Cas9, RNA-seq and pathway analysis.

RESULTS

We identified a germline heterozygous 23 Kb CDH1-TANGO6 deletion in a family with eight diffuse gastric cancers, six before age 30. Atypical HDGC high penetrance and young cancer-onset argued towards a role for the deleted region downstream of CDH1, which we proved to present accessible chromatin, and CDH1 promoter interactors in normal stomach. CRISPR-Cas9 edited cells mimicking the CDH1-TANGO6 deletion display the strongest CDH1 mRNA downregulation, more impacted adhesion-associated, type-I interferon immune-associated and oncogenic signalling pathways, compared to wild-type or CDH1-deleted cells. This finding solved an 18-year family odyssey and engaged carrier family members in a cancer prevention pathway of care.

CONCLUSION

In this work, we demonstrated that regulatory elements lying down-stream of CDH1 are part of a chromatin network that control CDH1 expression and influence cell transcriptome and associated signalling pathways, likely explaining high disease penetrance and very young cancer-onset. This study highlights the importance of incorporating scientific-technological updates and clinical guidelines in routine diagnosis, given their impact in timely genetic diagnosis and disease prevention.

Hereditary Diffuse Gastric Cancer

Hereditary diffuse gastric cancer (HDGC) is a dominantly inherited cancer syndrome characterized by a high incidence of diffuse gastric cancer (DGC) and lobular breast cancer (LBC). HDGC is caused by germline mutations in 2 genes involved in the epithelial adherens junction complex, CDH1 and CTNNA1. We discuss the genetics of HDGC and the variability of its clinical phenotype, in particular the variable penetrance of advanced DGC and LBC, both within and between families. We review the pathology of the disease, the mechanism of tumor initiation, and its natural history. Finally, we describe current best practice for the clinical management of HDGC, including emerging genetic testing criteria for the identification of new families, methods for endoscopic surveillance, the complications associated with prophylactic surgery, postoperative quality of life, and the emerging field of HDGC chemoprevention.

A DLG1-ARHGAP31-CDC42 axis is essential for the intestinal stem cell response to fluctuating niche Wnt signaling

A central factor in the maintenance of tissue integrity is the response of stem cells to variations in the levels of niche signals. In the gut, intestinal stem cells (ISCs) depend on Wnt ligands for self-renewal and proliferation. Transient increases in Wnt signaling promote regeneration after injury or in inflammatory bowel diseases, whereas constitutive activation of this pathway leads to colorectal cancer. Here, we report that Discs large 1 (Dlg1), although dispensable for polarity and cellular turnover during intestinal homeostasis, is required for ISC survival in the context of increased Wnt signaling. RNA sequencing (RNA-seq) and genetic mouse models demonstrated that DLG1 regulates the cellular response to increased canonical Wnt ligands. This occurs via the transcriptional regulation of Arhgap31, a GTPase-activating protein that deactivates CDC42, an effector of the non-canonical Wnt pathway. These findings reveal a DLG1-ARHGAP31-CDC42 axis that is essential for the ISC response to increased niche Wnt signaling.

Scribble and E-cadherin cooperate to control symmetric daughter cell positioning by multiple mechanisms

The fate of the two daughter cells is intimately connected to their positioning, which is in turn regulated by cell junction remodelling and orientation of the mitotic spindle. How multiple cues are integrated to dictate the ultimate positioning of daughters is not clear. Here, we identify novel mechanisms of regulation of daughter positioning in single MCF10A cells. The polarity protein, Scribble cooperates with E-cadherin for sequential roles in daughter positioning. First Scribble stabilises E-cadherin at the mitotic cortex as well as the retraction fibres, to mediate spindle orientation. Second, Scribble re-locates to the junction between the two daughters to allow a new E-cadherin-based-interface to form between them, influencing the width of the nascent daughter-daughter junction and subsequent cell positioning. Thus, E-cadherin and Scribble dynamically relocate to different intracellular sites during cell division to orient the mitotic spindle and control placement of the daughter cells after cell division. This article has an associated First Person interview with the first author of the paper.

Annexin A1 is a polarity cue that directs mitotic spindle orientation during mammalian epithelial morphogenesis

Oriented cell divisions are critical for the formation and maintenance of structured epithelia. Proper mitotic spindle orientation relies on polarised anchoring of force generators to the cell cortex by the evolutionarily conserved protein complex formed by the G_αi subunit of heterotrimeric G proteins, the Leucine-Glycine-Asparagine repeat protein (LGN) and the nuclear mitotic apparatus protein. However, the polarity cues that control cortical patterning of this ternary complex remain largely unknown in mammalian epithelia. Here we identify the membrane-associated protein Annexin A1 (ANXA1) as an interactor of LGN in mammary epithelial cells. Annexin A1 acts independently of G_αi to instruct the accumulation of LGN and nuclear mitotic apparatus protein at the lateral cortex to ensure cortical anchoring of Dynein-Dynactin and astral microtubules and thereby planar alignment of the mitotic spindle. Loss of Annexin A1 randomises mitotic spindle orientation, which in turn disrupts epithelial architecture and luminogenesis in three-dimensional cultures of primary mammary epithelial cells. Our findings establish Annexin A1 as an upstream cortical cue that regulates LGN to direct planar cell divisions during mammalian epithelial morphogenesis.

Automated Immunofluorescence Staining for Analysis of Mitotic Stages and Division Orientation in Brain Sections

Microcephaly often results from mitotic defects in neuronal progenitors, frequently by decreasing proliferation rates or shifting cell fates. During neurogenesis, oriented cell division-the molecular control of mitotic spindle positioning to control the axis of division-represents an important mechanism to balance expansion of the progenitor pool with generating cellular diversity. While mostly studied in the context of cortical development, more recently, spindle orientation has emerged as a key player in the formation of other brain regions such as the cerebellum. Here we describe methods to perform automated dual-color fluorescent immunohistochemistry on murine cerebellar sections using the mitotic markers phospho-Histone H3 and Survivin, and detail analytical and statistical approaches to display and compare division orientation datasets.

Cadherin-mediated adhesion takes control

The formation of a centralised apical membrane initiation site (AMIS) is a key event in epithelial cell polarisation. A recent study by Liang et al demonstrates that AMIS localisation relies on cadherin-mediated cell adhesion.

Understanding the underlying mechanisms governing spindle orientation: How far are we from there?

Proper spindle orientation is essential for cell fate determination and tissue morphogenesis. Recently, accumulating studies have elucidated several factors that regulate spindle orientation, including geometric, internal and external cues. Abnormality in these factors generally leads to defects in the physiological functions of various organs and the development of severe diseases. Herein, we first review models that are commonly used for studying spindle orientation. We then review a conservative heterotrimeric complex critically involved in spindle orientation regulation in different models. Finally, we summarize some cues that affect spindle orientation and explore whether we can establish a model that precisely elucidates the effects of spindle orientation without interfusing other spindle functions. We aim to summarize current models used in spindle orientation studies and discuss whether we can build a model that disturbs spindle orientation alone. This can substantially improve our understanding of how spindle orientation is regulated and provide insights to investigate this complex event.

Insights Into Mechanisms of Oriented Division From Studies in 3D Cellular Models

In multicellular organisms, epithelial cells are key elements of tissue organization. In developing tissues, cellular proliferation and differentiation are under the tight regulation of morphogenetic programs, that ensure the correct organ formation and functioning. In these processes, mitotic rates and division orientation are crucial in regulating the velocity and the timing of the forming tissue. Division orientation, specified by mitotic spindle placement with respect to epithelial apico-basal polarity, controls not only the partitioning of cellular components but also the positioning of the daughter cells within the tissue, and hence the contacts that daughter cells retain with the surrounding microenvironment. Daughter cells positioning is important to determine signal sensing and fate, and therefore the final function of the developing organ. In this review, we will discuss recent discoveries regarding the mechanistics of planar divisions in mammalian epithelial cells, summarizing technologies and model systems used to study oriented cell divisions in vitro such as three-dimensional cysts of immortalized cells and intestinal organoids. We also highlight how misorientation is corrected in vivo and in vitro, and how it might contribute to the onset of pathological conditions.

Diffuse gastric cancer: Emerging mechanisms of tumor initiation and progression

Gastric cancer is globally the fourth leading cause of cancer-related deaths. Patients with diffuse-type gastric cancer (DGC) particularly have a poor prognosis that only marginally improved over the last decades, as conventional chemotherapies are frequently ineffective and specific therapies are unavailable. Early-stage DGC is characterized by intramucosal lesions of discohesive cells, which can be present for many years before the emergence of advanced DGC consisting of highly proliferative and invasive cells. The mechanisms underlying the key steps of DGC development and transition to aggressive tumors are starting to emerge. Novel mouse- and organoid models for DGC, together with multi-omic analyses of DGC tumors, revealed contributions of both tumor cell-intrinsic alterations and gradual changes in the tumor microenvironment to DGC progression. In this review, we will discuss how these recent findings are leading towards an understanding of the cellular and molecular mechanisms responsible for DGC initiation and malignancy, which may provide opportunities for targeted therapies.

MicroRNA Profile Alterations in Parathyroid Carcinoma: Latest Updates and Perspectives

Simple Summary

Despite the considerable development of diagnostic tools, distinguishing between benign and malignant parathyroid tumors poses a significant diagnostic challenge. Epigenetic regulations, including noncoding microRNAs (miRNAs), have recently emerged as a new and promising source of biomarkers. MiRNAs are post-transcriptional regulators of gene expression. These tissue-specific molecules are known to be deregulated between cancer and normal cells. This review delineates changes in miRNA expression in parathyroid carcinoma (PC), advancing our understanding of PC tumorigenesis and emphasizing, at the same time, that miRNAs can be further exploited for diagnostic and therapeutic purposes.

Abstract

Parathyroid tumors are a genetically heterogenous group with a significant variability in clinical features. Due to a lack of specific signs and symptoms and uncertain histopathological criteria, parathyroid carcinomas (PCs) are challenging to diagnose, both before and after surgery. There is a great interest in searching for accurate molecular biomarkers for early detection, disease monitoring, and clinical management. Due to improvements in molecular pathology, the latest studies have reported that PC tumorigenesis is strongly linked to the epigenetic regulation of gene expression. MicroRNA (miRNA) profiling may serve as a helpful adjunct in distinguishing parathyroid adenoma (PAd) from PC and provide further insight into regulatory pathways involved in PTH release and parathyroid tumorigenesis. So far, only a few studies have attempted to show the miRNA signature for PC, and very few overlaps could be found between these relatively similar studies. A global miRNA downregulation was detected in PC compared with normal glands among differentially expressed miRNAs. This review summarizes changes in miRNA expression in PC and discusses the future research directions in this area.

The Transcription Factors Zeb1 and Snail Induce Cell Malignancy and Cancer Stem Cell Phenotype in Prostate Cells, Increasing Androgen Synthesis Capacity and Therapy Resistance

Prostate cancer (PCa) incidence has increased during the last decades, becoming one of the leading causes of death by cancer in men worldwide. During an extended period of prostate cancer, malignant cells are androgen-sensitive being testosterone the main responsible for tumor growth. Accordingly, treatments blocking production and action of testosterone are mostly used. However, during disease progression, PCa cells become androgen insensitive producing a castration-resistant stage with a worse prognosis. Overcoming castration-resistant prostate cancer (CRPC) has become a great challenge in the management of this disease. In the search for molecular pathways leading to therapy resistance, the epithelial-mesenchymal transition (EMT), and particularly the transcription factors zinc finger E-box-binding homeobox 1 (Zeb1) and zinc finger protein SNAI1 (Snail), master genes of the EMT, have shown to have pivotal roles. Also, the discovery that cancer stem cells (CSCs) can be generated de novo from their non-CSCs counterpart has led to the question whereas these EMT transcription factors could be implicated in this dynamic conversion between non-CSC and CSC. In this review, we analyze evidence supporting the idea that Zeb1 and Snail induce cell malignancy and cancer stem cell phenotype in prostate cells, increasing androgen synthesis capacity and therapy resistance.

Discovery of AL-GDa62 as a Potential Synthetic Lethal Lead for the Treatment of Gastric Cancer

Diffuse gastric cancer and lobular breast cancer are aggressive malignancies that are frequently associated with inactivating mutations in the tumor suppressor gene CDH1. Synthetic lethal (SL) vulnerabilities arising from CDH1 dysfunction represent attractive targets for drug development. Recently, SLEC-11 (1) emerged as a SL lead in E-cadherin-deficient cells. Here, we describe our efforts to optimize 1. Overall, 63 analogues were synthesized and tested for their SL activity toward isogenic mammary epithelial CDH1-deficient cells (MCF10A-CDH1^-/-). Among the 26 compounds with greater cytotoxicity, AL-GDa62 (3) was four-times more potent and more selective than 1 with an EC₅₀ ratio of 1.6. Furthermore, 3 preferentially induced apoptosis in CDH1^-/- cells, and Cdh1^-/- mammary and gastric organoids were significantly more sensitive to 3 at low micromolar concentrations. Thermal proteome profiling of treated MCF10A-CDH1^-/- cell protein lysates revealed that 3 specifically inhibits TCOF1, ARPC5, and UBC9. In vitro, 3 inhibited SUMOylation at low micromolar concentrations.

Fluorescence Microscopy-An Outline of Hardware, Biological Handling, and Fluorophore Considerations

Fluorescence microscopy has become a critical tool for researchers to understand biological processes at the cellular level. Micrographs from fixed and live-cell imaging procedures feature in a plethora of scientific articles for the field of cell biology, but the complexities of fluorescence microscopy as an imaging tool can sometimes be overlooked or misunderstood. This review seeks to cover the three fundamental considerations when designing fluorescence microscopy experiments: (1) hardware availability; (2) amenability of biological models to fluorescence microscopy; and (3) suitability of imaging agents for intended applications. This review will help equip the reader to make judicious decisions when designing fluorescence microscopy experiments that deliver high-resolution and informative images for cell biology.

Modulation of E-Cadherin and N-Cadherin by ovarian steroids and embryonic stimuli

Endometrium is a dynamic tissue that undergoes extensive remodelling to attain a receptive state which is further modulated in presence of an embryo for successful initiation of pregnancy. Cadherins are the proteins of the junctional complex of which E-cadherin (E-Cad) is crucial for maintaining epithelial cell state and integrity of the epithelial barrier; gain of N-cadherin (N-Cad) in epithelial cells leads to epithelial to mesenchymal transition (EMT). In the present study, we investigated the expression of E-Cad and N-Cad in the mouse endometrial luminal epithelium and its modulation by estrogen, progesterone, and embryonic stimuli. We observed that E-Cad is diffusely expressed in the luminal epithelium of mouse endometrium during the estrus stage and upon estrogen treatment. It is apico-laterally and basolaterally sorted at the diestrus stage and in response to the combined treatment of estrogen and progesterone. In 3D spheroids of human endometrial epithelial cells, combined treatment with estrogen and progesterone led to lateral sorting of E-Cad without any effects on its mRNA levels. at the time of embryo implantation, there is loss of E-Cad along with the gain of N-Cad and SNAIL expression suggestive of EMT in the luminal epithelium. This EMT is possibly driven by embryonic stimuli as treatment with estrogen and progesterone did not lead to the gain of N-Cad expression in the mouse endometrium in vivo or in human endometrial epithelial cells in vitro. In conclusion, the present study demonstrates that steroid hormones directly affect E-Cad sorting in the endometrial epithelium which undergo EMT in response to embryonic stimuli.

Oxyresveratrol inhibits human colon cancer cell migration through regulating epithelial-mesenchymal transition and microRNA

The major cause of death in colorectal cancer (CRC) patients is metastasis. Moreover, lots of studies have emphasized that the epithelial-mesenchymal transition (EMT) is a pivotal step in metastasis. Both transforming growth factor beta (TGF-β) and dysregulation of microRNAs (miRNAs) can induce or regulate EMT, promoting the loss of intercellular adhesion and increased motility of cancer cells. Therefore, it is necessary to prevent or inhibit the metastasis of colorectal cancer. Relatively little is known about the anti-metastatic effect of oxyresveratrol (OXY), a natural derivative of resveratrol (RES), compared to RES. Accordingly, RES was used as the positive control to investigate the effects of OXY on colon cancer cell migration. The results showed that OXY could significantly inhibit cell migration (67.17% ± 0.04, 64.89% ± 0.04) compared to RES (84.6% ± 0.07, 76.34% ± 0.08) in HCT116 cells and TGF-β-induced HT-29 cells, respectively, via Snail/E-cadherin expression. In addition, OXY improved EMT-related miRNA expression through, for example, lowering the levels of miR-3687 and miR-301a-3p while upregulating miR-3612 in TGF-β-induced HT-29 cells. In conclusion, OXY inhibits human colon cancer cell migration by regulating EMT and miRNAs. Based on these findings, it can be stated that OXY promotes anti-metastatic properties in CRC.

Spindle positioning and its impact on vertebrate tissue architecture and cell fate

In multicellular systems, oriented cell divisions are essential for morphogenesis and homeostasis as they determine the position of daughter cells within the tissue and also, in many cases, their fate. Early studies in invertebrates led to the identification of conserved core mechanisms of mitotic spindle positioning centred on the Gαi-LGN-NuMA-dynein complex. In recent years, much has been learnt about the way this complex functions in vertebrate cells. In particular, studies addressed how the Gαi-LGN-NuMA-dynein complex dynamically crosstalks with astral microtubules and the actin cytoskeleton, and how it is regulated to orient the spindle according to cellular and tissue-wide cues. We have also begun to understand how dynein motors and actin regulators interact with mechanosensitive adhesion molecules sensing extracellular mechanical stimuli, such as cadherins and integrins, and with signalling pathways so as to respond to extracellular cues instructing the orientation of the division axis in vivo. In this Review, with the focus on epithelial tissues, we discuss the molecular mechanisms of mitotic spindle orientation in vertebrate cells, and how this machinery is regulated by epithelial cues and extracellular signals to maintain tissue cohesiveness during mitosis. We also outline recent knowledge of how spindle orientation impacts tissue architecture in epithelia and its emerging links to the regulation of cell fate decisions. Finally, we describe how defective spindle orientation can be corrected or its effects eliminated in tissues under physiological conditions, and the pathological implications associated with spindle misorientation.

Three-dimensional geometry controls division symmetry in stem cell colonies

Proper control of division orientation and symmetry, largely determined by spindle positioning, is essential to development and homeostasis. Spindle positioning has been extensively studied in cells dividing in two-dimensional (2D) environments and in epithelial tissues, where proteins such as NuMA (also known as NUMA1) orient division along the interphase long axis of the cell. However, little is known about how cells control spindle positioning in three-dimensional (3D) environments, such as early mammalian embryos and a variety of adult tissues. Here, we use mouse embryonic stem cells (ESCs), which grow in 3D colonies, as a model to investigate division in 3D. We observe that, at the periphery of 3D colonies, ESCs display high spindle mobility and divide asymmetrically. Our data suggest that enhanced spindle movements are due to unequal distribution of the cell-cell junction protein E-cadherin between future daughter cells. Interestingly, when cells progress towards differentiation, division becomes more symmetric, with more elongated shapes in metaphase and enhanced cortical NuMA recruitment in anaphase. Altogether, this study suggests that in 3D contexts, the geometry of the cell and its contacts with neighbors control division orientation and symmetry. This article has an associated First Person interview with the first author of the paper.

(S,R)3-(4-Hydroxyphenyl)-4,5-Dihydro-5-Isoxazole Acetic Acid Methyl Ester Inhibits Epithelial-to-Mesenchymal Transition through TGF-β/Smad4 Axis in Nasopharyngeal Carcinoma

BACKGROUND

Macrophage migration inhibitory factor (MIF), originally reported as an inflammation regulating molecule, is elevated in various cancer cells, which may promote carcinogenesis. Meanwhile, ISO-1 is a potent small molecular inhibitor of MIF, which has not been investigated in nasopharyngeal carcinoma (NPC); hence the impact of ISO-1 on NPC cells remains to be illustrated.

OBJECTIVE

This study intended to explore the biological function of ISO-1 in NPC cells in vitro and prove a possibility of ISO-1 being a novel agent in NPC treatments.

METHODS

Gene expression of MIF in Head and Neck squamous cell carcinoma were obtained from The Cancer Genome Atlas (TCGA) database. Nasal pharyngeal tissues were collected from adult patients undergoing nasopharyngeal biopsy for MIF level detection. Proliferation of NPC cell lines 5-8B and 6-10B was studied using Cell Counting Kit-8 (CCK-8) assay and plate-colony-formation assay, apoptosis was determined by flow cytometry and TUNEL staining, migration and invasion capacities were measured by wound-healing assay and transwell assay, all to explore the function of ISO-1 in NPC cells in vitro. Epithelial-to-mesenchymal transition (EMT) level of NPC cells was determined by Western blot analysis and immunofluorescence assay.

RESULTS

Transcript level of MIF was significantly higher in head and neck squamous cell carcinoma. Protein MIF was overexpressed in human NPC tissues compared to non-cancerous ones, and its expression could be compromised by ISO-1 in vitro. 100μM ISO-1 significantly hindered NPC cells migration and invasion capacities in vitro but acted relatively poorly on proliferation and apoptosis. Immunofluorescence assay and Western blotting implied a down-regulated EMT level through TGF-β/Smad4 axis in ISO-1 treated NPC cells compared to the vehicle.

CONCLUSION

This study indicated that MIF antagonist ISO-1 holds impact on NPC progression by influencing the migration and invasion of NPC cells ISO-1 inhibits the EMT process of NPC cells through TGF-β/Smad4 axis, supporting that prudent application of ISO-1 may be a potential adjuvant treatment for NPC.

BZD9L1 sirtuin inhibitor: Identification of key molecular targets and their biological functions in HCT 116 colorectal cancer cells

BZD9L1 was previously described as a SIRT1/2 inhibitor with anti-cancer activities in colorectal cancer (CRC), either as a standalone chemotherapy or in combination with 5-fluorouracil. BZD9L1 was reported to induce apoptosis in CRC cells; however, the network of intracellular pathways and crosstalk between molecular players mediated by BZD9L1 is not fully understood. This study aimed to uncover the mechanisms involved in BZD9L1-mediated cytotoxicity based on previous and new findings for the prediction and identification of related pathways and key molecular players. BZD9L1-regulated candidate targets (RCTs) were identified using a range of molecular, cell-based and biochemical techniques on the HCT 116 cell line. BZD9L1 regulated major cancer pathways including Notch, p53, cell cycle, NFκB, Myc/MAX, and MAPK/ERK signalling pathways. BZD9L1 also induced reactive oxygen species (ROS), regulated apoptosis-related proteins, and altered cell polarity and adhesion profiles. In silico analyses revealed that most RCTs were interconnected, and were involved in the modulation of catalytic activity, metabolism and transcription regulation, response to cytokines, and apoptosis signalling pathways. These RCTs were implicated in p53-dependent apoptosis pathway. This study provides the first assessment of possible associations of molecular players underlying the cytotoxic activity of BZD9L1, and establishes the links between RCTs and apoptosis through the p53 pathway.

Mechanoregulation of PDZ Proteins, An Emerging Function

Mechanical forces have emerged as essential regulators of cell organization, proliferation, migration, and polarity to regulate cellular and tissue homeostasis. Changes in forces or loss of the cellular response to them can result in abnormal embryonic development and diseases. Over the past two decades, many efforts have been put in deciphering the molecular mechanisms that convert forces into biochemical signals, allowing for the identification of many mechanotransducer proteins. Here we discuss how PDZ proteins are emerging as new mechanotransducer proteins by altering their conformations or localizations upon force loads, leading to the formation of macromolecular modules tethering the cell membrane to the actin cytoskeleton.

Expression of Acute Phase Protein, Glial Fibrillary Acidic Protein, Epithelial Cadherin, and S100 Protein in Brain Tissues from Natural Cases of Ovine Encephalitic Listeriosis

Listeriosis is a disease that is induced by infection with the Gram-positive bacterium Listeria monocytogenes. Much is still unknown about the pathogenesis of encephalitic listeriosis. We aimed to identify the contribution of glial fibrillary acidic protein (GFAP), epithelial cadherin (E-cadherin), S100, and acute-phase proteins (APPs) in pathogenesis, clinical and preclinical diagnosis of natural cases of encephalitic listeriosis. Of 1,325 Ossimi sheep, 64 were suspected of having listeriosis from 2018 to 2020. Prospective cohort evaluation of clinical and postmortem findings was performed, in addition to bacterial isolation, the measurement of APPs in serum and cerebrospinal fluid (CSF), and the histopathological and immunohistochemical evaluation of GFAP, S100, and E-cadherin. Infected sheep showed nervous symptoms ranging from neck stretching to complete paralysis. APPs were significantly increased in the CSF of both clinically and preclinically diseased animals; however, serum APPs were only significantly increased in clinically diseased animals. Histopathological evaluation revealed microabscesses, meningoencephalitis, and perivascular cuffing of the brainstem of infected sheep. Immunohistochemical investigations revealed strong expression of GFAP and S100 in necrotic areas and negative expression of E-cadherin. The measurement of CSF APPs could be useful in the preclinical diagnosis of sheep listeriosis. GFAP and S100 proteins could be involved in the pathogenesis of listeriosis; however, E-cadherin does not appear to be involved.

Scrib module proteins: Control of epithelial architecture and planar spindle orientation

The Scrib module proteins, Scrib, Dlg, and Lgl, are conserved regulators of cell polarity in diverse biological contexts. Originally discovered as neoplastic tumor suppressors in the fruit fly Drosophila melanogaster, disruption of Scrib module components leads to tumorigenesis in mammalian epithelia and is associated with human cancers. With multiple protein interacting domains, Scrib module proteins function as determinants of basolateral identity in epithelial cells with apical-basal polarity while acting as signaling platform scaffold proteins. Recent studies have further revealed novel roles of the Scrib module in the control of epithelial architecture, ranging from polarity establishment and tricellular junction formation to planar spindle orientation during cell division. This review updates the current understanding of the molecular nature and physiological functions of the Scrib module with a focus on in vivo studies, providing a framework for how these protein dynamics affect the processes of epithelial organization.

E-cadherin expression is inversely correlated with aging and inflammation in the prostate

INTRODUCTION AND OBJECTIVE

Benign prostatic hyperplasia (BPH) is a prostatic disease that is significantly associated with aging. However, it is not well understood how aging contributes to BPH pathogenesis. Several factors associated with an increased risk of BPH are also associated with increasing age, including chronic inflammation and declining epithelial barrier function. Thus, this study explored the potential associations between aging, loss of adherens junction protein E-cadherin and the presence of inflammatory mediators in prostate tissue specimens from healthy young donor and BPH patients.

METHODS

Serial prostate sections from a cohort of five donors aged 15-26 years and 13 BPH patients aged 50-77 years were immunostained with E-cadherin, COX-2, CD4, CD8, CD20 and CD68. E-cadherin and COX-2 H-Scores and the number of inflammatory cells were calculated for the same area in donor, normal adjacent prostate to BPH (NAP) and BPH specimens. Quantification and statistical correlation analyses were performed for comparisons between groups.

RESULTS

E-cadherin was decreased in aged NAP tissues and in BPH compared to young donor tissue. E-cadherin was inversely correlated with age and infiltration of inflammatory cells in NAP compared to young healthy donor prostate. Stromal COX-2 was positively correlated with age and inflammation. E-cadherin was further down-regulated in BPH, while COX-2 H-Scores were not significantly altered in BPH compared to NAP.

CONCLUSIONS

These findings suggest that aging is associated with down-regulation of E-cadherin and up-regulation of stromal COX-2 immunostaining in the prostate. E-cadherin immunostaining was inversely associated with age and inflammation, while stromal COX-2 immunostaining was positively associated with age and inflammation in the prostate. These findings suggest that the prostate epithelial barrier is altered and inflammation is increased with age in the prostate. These changes are further exacerbated in BPH, and may be involved in BPH pathogenesis.

Prostate-Specific Deletion of Cdh1 Induces Murine Prostatic Inflammation and Bladder Overactivity

Benign prostatic hyperplasia (BPH) is an age-related debilitating prostatic disease that is frequently associated with prostatic inflammation and bothersome lower urinary tract symptoms (LUTS). Animal models have shown that formalin- and bacterial-induced prostatic inflammation can induce bladder dysfunction; however, the underlying mechanisms contributing to prostatic inflammation in BPH and bladder dysfunction are not clear. We previously reported that E-cadherin expression in BPH is downregulated in hyperplastic nodules compared with expression in adjacent normal tissues. Here, we explored the potential consequences of prostatic E-cadherin downregulation on the prostate and bladder in vivo using an inducible murine model of prostate luminal epithelial-specific deletion of Cdh1. The prostate-specific antigen (PSA)-CreERT2 transgenic mouse strain expressing tamoxifen-inducible CreERT2 recombinase driven by a 6-kb human PSA promoter/enhancer was crossed with the B6.129-Cdh1tm2Kem/J mouse to generate bigenic PSA-CreERT2/Cdh1-/- mice. Deletion of E-cadherin was induced by transient administration of tamoxifen when mice reached sexual maturity (7 weeks of age). At 21 to 23 weeks of age, the prostate, bladder, and prostatic urethra were examined histologically, and bladder function was assessed using void spot assays and cystometry. Mice with Cdh1 deletion had increased prostatic inflammation, prostatic epithelial hyperplasia, and stromal changes at 21 to 23 weeks of age, as well as changes in bladder voiding function compared with age-matched controls. Thus, loss of E-cadherin in the murine prostate could result in prostatic defects that are characteristic of BPH and LUTS, suggesting that E-cadherin downregulation could be a driving force in human BPH development and progression.

RAS-mediated suppression of PAR3 and its effects on SCC initiation and tissue architecture occur independently of hyperplasia

Proper epithelial development and homeostasis depends on strict control of oriented cell division. Current evidence shows that this process is regulated by intrinsic polarity factors and external spatial cues. Owing to the lack of an appropriate model system that can recapitulate the architecture of the skin, deregulation of spindle orientation in human epithelial carcinoma has never been investigated. Here, using an inducible model of human squamous cell carcinoma (SCC), we demonstrate that RAS-dependent suppression of PAR3 (encoded by PARD3) accelerates epithelial disorganization during early tumorigenesis. Diminished PAR3 led to loss of E-cadherin-mediated cell adhesion, which in turn contributed to misoriented cell division. Pharmacological inhibition of the MAPK pathway downstream of RAS activation reversed the defects in PAR3 expression, E-cadherin-mediated cell adhesion and mitotic spindle orientation. Thus, temporal analysis of human neoplasia provides a powerful approach to study cellular and molecular transformations during early oncogenesis, which allowed identification of PAR3 as a critical regulator of tissue architecture during initial human SCC development.

Wwox Deficiency Causes Downregulation of Prosurvival ERK Signaling and Abnormal Homeostatic Responses in Mouse Skin

Deficiency of tumor suppressor WW domain-containing oxidoreductase (WWOX) in humans and animals leads to growth retardation and premature death during postnatal developmental stages. Skin integrity is essential for organism survival due to its protection against dehydration and hypothermia. Our previous report demonstrated that human epidermal suprabasal cells express WWOX protein, and the expression is gradually increased toward the superficial differentiated cells prior to cornification. Here, we investigated whether abnormal skin development and homeostasis occur under Wwox deficiency that may correlate with early death. We determined that keratinocyte proliferation and differentiation were decreased, while apoptosis was increased in Wwox^–/– mouse epidermis and primary keratinocyte cultures and WWOX-knockdown human HaCaT cells. Without WWOX, progenitor cells in hair follicle junctional zone underwent massive proliferation in early postnatal developmental stages and the stem/progenitor cell pools were depleted at postnatal day 21. These events lead to significantly decreased epidermal thickness, dehydration state, and delayed hair development in Wwox^–/– mouse skin, which is associated with downregulation of prosurvival MEK/ERK signaling in Wwox^–/– keratinocytes. Moreover, Wwox depletion results in substantial downregulation of dermal collagen contents in mice. Notably, Wwox^–/– mice exhibit severe loss of subcutaneous adipose tissue and significant hypothermia. Collectively, our knockout mouse model supports the validity of WWOX in assisting epidermal and adipose homeostasis, and the involvement of prosurvival ERK pathway in the homeostatic responses regulated by WWOX.

Molecular tracing of prostate cancer lethality

Prostate cancer is diagnosed mostly in men over the age of 50 years, and has favorable 5-year survival rates due to early cancer detection and availability of curative surgical management. However, progression to metastasis and emergence of therapeutic resistance are responsible for the majority of prostate cancer mortalities. Recent advancement in sequencing technologies and computational capabilities have improved the ability to organize and analyze large data, thus enabling the identification of novel biomarkers for survival, metastatic progression and patient prognosis. Large-scale sequencing studies have also uncovered genetic and epigenetic signatures associated with prostate cancer molecular subtypes, supporting the development of personalized targeted-therapies. However, the current state of mainstream prostate cancer management does not take full advantage of the personalized diagnostic and treatment modalities available. This review focuses on interrogating biomarkers of prostate cancer progression, including gene signatures that correspond to the acquisition of tumor lethality and those of predictive and prognostic value in progression to advanced disease, and suggest how we can use our knowledge of biomarkers and molecular subtypes to improve patient treatment and survival outcomes.

Telophase correction refines division orientation in stratified epithelia

During organogenesis, precise control of spindle orientation balances proliferation and differentiation. In the developing murine epidermis, planar and perpendicular divisions yield symmetric and asymmetric fate outcomes, respectively. Classically, division axis specification involves centrosome migration and spindle rotation, events occurring early in mitosis. Here, we identify a novel orientation mechanism which corrects erroneous anaphase orientations during telophase. The directionality of reorientation correlates with the maintenance or loss of basal contact by the apical daughter. While the scaffolding protein LGN is known to determine initial spindle positioning, we show that LGN also functions during telophase to reorient oblique divisions toward perpendicular. The fidelity of telophase correction also relies on the tension-sensitive adherens junction proteins vinculin, α-E-catenin, and afadin. Failure of this corrective mechanism impacts tissue architecture, as persistent oblique divisions induce precocious, sustained differentiation. The division orientation plasticity provided by telophase correction may enable progenitors to adapt to local tissue needs.

E-Cadherin Downregulation is Mediated by Promoter Methylation in Canine Prostate Cancer

E-cadherin is a transmembrane glycoprotein responsible for cell-to-cell adhesion, and its loss has been associated with metastasis development. Although E-cadherin downregulation was previously reported in canine prostate cancer (PC), the mechanism involved in this process is unclear. It is well established that dogs, besides humans, spontaneously develop PC with high frequency; therefore, canine PC is an interesting model to study human PC. In human PC, CDH1 methylation has been associated with E-cadherin downregulation. However, no previous studies have described the methylation pattern of CDH1 promoter in canine PC. Herein, we evaluated the E-cadherin protein and gene expression in canine PC compared to normal tissues. DNA methylation pattern was investigated as a regulatory mechanism of CDH1 silencing. Our cohort is composed of 20 normal prostates, 20 proliferative inflammatory atrophy (PIA) lesions, 20 PC, and 11 metastases from 60 dogs. The E-cadherin protein expression was assessed by immunohistochemistry and western blotting and gene expression by qPCR. Bisulfite- pyrosequencing assay was performed to investigate the CDH1 promoter methylation pattern. Membranous E-cadherin expression was observed in all prostatic tissues. A higher number of E-cadherin negative cells was detected more frequently in PC compared to normal and PIA samples. High-grade PC showed a diffuse membranous positive immunostaining. Furthermore, PC patients with a higher number of E-cadherin negative cells presented shorter survival time and higher Gleason scores. Western blotting and qPCR assays confirmed the immunohistochemical results, showing lower E-cadherin protein and gene expression levels in PC compared to normal samples. We identified CDH1 promoter hypermethylation in PIA and PC samples. An in vitro assay with two canine prostate cancer cells (PC1 and PC2 cell lines) was performed to confirm the methylation as a regulatory mechanism of E-cadherin expression. PC1 cell line presented CDH1 hypermethylation and after 5-Aza-dC treatment, a decreased CDH1 methylation and increased gene expression levels were observed. Positive E-cadherin cells were massively found in metastases (mean of 90.6%). In conclusion, low levels of E-cadherin protein, gene downregulation and CDH1 hypermethylation was detected in canine PC. However, in metastatic foci occur E-cadherin re-expression confirming its relevance in these processes.

The comprehensive role of E-cadherin in maintaining prostatic epithelial integrity during oncogenic transformation and tumor progression

E-cadherin complexes with the actin cytoskeleton via cytoplasmic catenins and maintains the functional characteristics and integrity of the epithelia in normal epithelial tissues. Lost expression of E-cadherin disrupts this complex resulting in loss of cell polarity, epithelial denudation and increased epithelial permeability in a variety of tissues. Decreased expression of E-cadherin has also been observed in invasive and metastatic human tumors. In this study, we investigated the effect of E-cadherin loss in prostatic epithelium using newly developed genetically engineered mouse models. Deletion of E-cadherin in prostatic luminal epithelial cells with modified probasin promoter driven Cre (PB-Cre4) induced the development of mouse prostatic intraepithelial neoplasia (PIN). An increase in levels of cytoplasmic and nuclear β-catenin appeared in E-cadherin deleted atypical cells within PIN lesions. Using various experimental approaches, we further demonstrated that the knockdown of E-cadherin expression elevated free cytoplasmic and nuclear β-catenin and enhanced androgen-induced transcription and cell growth. Intriguingly, pathological changes representing prostatic epithelial cell denudation and increased apoptosis accompanied the above PIN lesions. The essential role of E-cadherin in maintaining prostatic epithelial integrity and organization was further demonstrated using organoid culture approaches. To directly assess the role of loss of E-cadherin in prostate tumor progression, we generated a new mouse model with bigenic Cdh1 and Pten deletion in prostate epithelium. Early onset, aggressive tumor phenotypes presented in the compound mice. Strikingly, goblet cell metaplasia was observed, intermixed within prostatic tumor lesions of the compound mice. This study provides multiple lines of novel evidence demonstrating a comprehensive role of E-cadherin in maintaining epithelial integrity during the course of prostate oncogenic transformation, tumor initiation and progression.

The biological significance of E-cadherin in maintaining prostatic epithelial integrity and related molecular mechanisms are still unclear. In this study, using mouse genetic tools, we directly address this important and unresolved question. Conditional deletion of E-cadherin in mouse prostatic epithelia resulted in prostatic intraepithelial neoplasia (PIN) development but no prostatic tumor formation. Both in vivo and in vitro data showed that loss of E-cadherin modulates the cellular localization of β-catenin, elevates its cytoplasmic and nuclear levels, and enhances its activity in transcription and cell proliferation. Intriguingly, in addition to PIN lesions, increased epithelial denudation and cell apoptosis also appeared within PIN lesions. This implicates that although lost E-cadherin is sufficient to introduce oncogenic transformation in prostatic epithelia, it also induces cell apoptosis and disrupts epithelial structure, preventing atypical PIN cells from progressing to tumor cells. Simultaneous deletion of Pten, a tumor suppressor, and E-cadherin in prostatic epithelia resulted in early onset, invasive prostatic tumors with admixture of goblet cells. These results demonstrate a critical role of E-cadherin in promoting prostatic tumor transdifferentiation and progression. This study further elucidates the dynamic role of E-cadherin in maintaining prostatic epithelial integrity during tumor initiation and progression.

The role of polarisation of circulating tumour cells in cancer metastasis

Metastasis is the spread of cancer cells from a primary tumour to a distant site of the body. Metastasising tumour cells have to survive and readjust to different environments, such as heterogeneous solid tissues and liquid phase in lymph- or blood circulation, which they achieve through a high degree of plasticity that renders them adaptable to varying conditions. One defining characteristic of the metastatic process is the transition of tumour cells between different polarised phenotypes, ranging from differentiated epithelial polarity to migratory front-rear polarity. Here, we review the polarisation types adopted by tumour cells during the metastatic process and describe the recently discovered single-cell polarity in liquid phase observed in circulating tumour cells. We propose that single-cell polarity constitutes a mode of polarisation of the cell cortex that is uncoupled from the intracellular polarisation machinery, which distinguishes single-cell polarity from other types of polarity identified so far. We discuss how single-cell polarity can contribute to tumour metastasis and the therapeutic potential of this new discovery.

Eph signaling in mitotic spindle orientation: what´s your angle here?

The orientation of the mitotic spindle is a crucial process during development and adult tissue homeostasis and multiple mechanisms have been shown to intrinsically regulate this process. However, much less is known about the extrinsic cues involved in modulating spindle orientation. We have recently uncovered a novel function of Eph intercellular signaling in regulating spindle alignment by ultimately ensuring the correct cortical distribution of central components within the intrinsic spindle orientation machinery. Here, we comment on these results, novel questions that they open and potential additional research to address in the future.

Cell shape and intercellular adhesion regulate mitotic spindle orientation

Cell division orientation plays an essential role in tissue morphogenesis and cell fate decision. Recent studies showed that either cell shape or adhesion geometry can regulate the orientation of mitotic spindles and thereby the cell division orientation. However, how they together regulate the spindle orientation remains largely unclear. In this work, we use a general computational model to investigate the competitive mechanism of determining the spindle orientation between cell shape and intercellular adhesion in epithelial cells. We find the spindle orientation is dominated by the intercellular adhesion when the cell shape anisotropy is small, but dominated by the cell shape when the shape anisotropy is large. A strong adhesion and moderate adhesive size can ensure the planar division of epithelial cells with large apico-basal elongation. We also find the spindle orientation could be perpendicular to the adhesive region when only one side of the cell is adhered to an E-cadherin-coated matrix. But after the cell is compressed, the spindle orientation is governed by the cell shape and the spindle will be parallel to the adhesive region when the cell shape anisotropy is large. Finally, we demonstrate the competition between cell shape and tricellular junctions can also effectively regulate the spindle orientation.

Role of adherens junctions and apical-basal polarity of neural stem/progenitor cells in the pathogenesis of neurodevelopmental disorders: a novel perspective on congenital Zika syndrome

Radial glial cells (RGCs) are the neural stem/progenitor cells (NSPCs) that give rise to most of neurons and glial cells that constitute the adult central nervous system. A hallmark of RGCs is their polarization along the apical-basal axis. They extend a long basal process that contacts the pial surface and a short apical process to the ventricular surface. Adherens junctions (AJs) are organized as belt-like structures at the most-apical lateral plasma membrane of the apical processes. These junctional complexes anchor RGCs to each other and allow the recruitment of cytoplasmic proteins that act as apical-basal determinants. It has been proposed that disruption of AJs underlies the onset of different neurodevelopmental disorders. In fact, studies performed in different animal models indicate that loss of function of AJs-related proteins in NSPCs can disrupt cell polarity, imbalance proliferation and/or differentiation rates and increase cell death, which, in turn, lead to disruption of the cytoarchitecture of the ventricular zone, protrusion of non-polarized cells into the ventricles, cortical thinning, and ventriculomegaly/hydrocephalus, among other neuropathological findings. Recent Zika virus (ZIKV) outbreaks and the high comorbidity of ZIKV infection with congenital neurodevelopmental defects have led to the World Health Organization to declare a public emergency of international concern. Thus, noteworthy advances have been made in clinical and experimental ZIKV research. This review summarizes the current knowledge regarding the function of AJs in normal and pathological corticogenesis and focuses on the neuropathological and cellular mechanisms involved in congenital ZIKV syndrome, highlighting the potential role of cell-to-cell junctions between NSPCs in the etiopathogenesis of such syndrome.

The interaction between CASK and the tumour suppressor Dlg1 regulates mitotic spindle orientation in mammalian epithelia

Oriented cell divisions are important for the formation of normal epithelial structures. Dlg1, a tumour suppressor, is required for mitotic spindle orientation in Drosophila epithelia and chick neuroepithelia, but how Dlg1 is localised to the membrane and its importance in mammalian epithelia are unknown. We show that Dlg1 is required in non-transformed mammalian epithelial cells for oriented cell divisions and normal lumen formation. We demonstrate that the MAGUK protein CASK, a membrane-associated scaffold, is the factor responsible for Dlg1 membrane localisation during spindle orientation, thereby identifying a new cellular function for CASK. Depletion of CASK leads to misoriented divisions in 3D, and to the formation of multilumen structures in cultured kidney and breast epithelial cells. Blocking the CASK-Dlg1 interaction with an interfering peptide, or by deletion of the CASK-interaction domain of Dlg1, disrupts spindle orientation and causes multilumen formation. We show that the CASK-Dlg1 interaction is important for localisation of the canonical LGN-NuMA complex known to be required for spindle orientation. These results establish the importance of the CASK-Dlg1 interaction in oriented cell division and epithelial integrity.This article has an associated First Person interview with the first author of the paper.

Division orientation: disentangling shape and mechanical forces

Oriented cell divisions are essential for the generation of cell diversity and for tissue shaping during morphogenesis. Cells in tissues are mechanically linked to their neighbors, upon which they impose, and from which they experience, physical force. Recent work in multiple systems has revealed that tissue-level physical forces can influence the orientation of cell division. A long-standing question is whether forces are communicated to the spindle orienting machinery via cell shape or directly via mechanosensing intracellular machinery. In this article, we review the current evidence from diverse model systems that show spindles are oriented by tissue-level physical forces and evaluate current models and molecular mechanisms proposed to explain how the spindle orientation machinery responds to extrinsic force.

Scribble: A master scaffold in polarity, adhesion, synaptogenesis, and proliferation

Key events ranging from cell polarity to proliferation regulation to neuronal signaling rely on the assembly of multiprotein adhesion or signaling complexes at particular subcellular sites. Multidomain scaffolding proteins nucleate assembly and direct localization of these complexes, and the protein Scribble and its relatives in the LAP protein family provide a paradigm for this. Scribble was originally identified because of its role in apical-basal polarity and epithelial integrity in Drosophila melanogaster It is now clear that Scribble acts to assemble and position diverse multiprotein complexes in processes ranging from planar polarity to adhesion to oriented cell division to synaptogenesis. Here, we explore what we have learned about the mechanisms of action of Scribble in the context of its multiple known interacting partners and discuss how this knowledge opens new questions about the full range of Scribble protein partners and their structural and signaling roles.