Evolution and diversity of cadherins and catenins

PCDHGA10 as a Potential Biomarker of Lung Squamous Cell Carcinoma Based on Bioinformatics and Experimental Verification

Procalcitonin gamma subfamily A, 10 (PCDHGA10) is a member of the procalcitonin gamma gene cluster, which is associated with neuronal synapse development. However, there are lack of studies on the role and potential prognostic value of PCDHGA10 in lung squamous cell carcinoma (LUSC). We analyzed the RNAseq data of PCDHGA10 to compare their expression differences. Then survival analysis, tumor microenvironment (TME) analysis, and mutation analysis were carried out. Additionally, we performed gene ontology (GO) and kyoto gene encyclopedia (KEGG) enrichment analyses to explore potential signal pathways. PCDHGA10 protein expression was evaluated using immunohistochemistry (IHC) on tissue microarrays (HLugS180Su02). By microarray analysis and database analysis, we found that PCDHGA10 was significantly highly expressed in LUSC. Sufferers with elevated PCDHGA10 levels exhibited a worse prognosis, according to the survival analysis. The PCDHGA10 mutation was also linked to LUSC patient prognosis. Besides, PCDHGA10 was closely related to tumor immune cell infiltration and immune checkpoints. In conclusion, PCDHGA10 is expected to become a new molecular marker for LUSC.

A novel beta-catenin homologue from the earthworm Eisenia andrei: Identification and characterization during embryonic development, segment regeneration, and immune response

Evolutionarily, Wnt/β-catenin signaling is well-conserved and supports several key cell-biological processes (e.g. adhesion and proliferation). Its crucial component, β-catenin, has been described in several organisms, however, its identification and characterization are notably lacking in annelid earthworms. Here, we report a novel β-catenin homologue from the earthworm Eisenia andrei, termed Ea-β-catenin. The full-length 3253 nt Ea-β-catenin mRNA includes an open reading frame of 2499 nt encoding a putative protein with 833 amino acid residues that comprise 11 classical armadillo-repeat regions. Phylogenetic analysis indicates that Ea-β-catenin shows strong homology with Lophotrochozoan β-catenins. Ubiquitous, but variable expressions of Ea-β-catenin were observed in distinct earthworm tissues. During embryogenesis, Ea-β-catenin mRNA gradually increased from the E1 to E4 developmental stages. Regeneration experiments revealed an inverse correlation between Ea-β-catenin mRNA levels and the rate of EdU+/PY489-β-catenin+ proliferating cells during the second week of the posterior blastema formation. In vitro exposures to poly(I:C) and zymosan significantly increased Ea-β-catenin mRNA levels, while small molecule Wnt-pathway modulators such as LiCl or iCRT14 increased or decreased Ea-β-catenin mRNA expression, and nuclear translocation of PY489-β-catenin, respectively. These novel results pave the way for follow-up studies aimed at characterizing additional members of the Wnt/β-catenin pathway that may be involved in embryonic and/or postembryonic development, as well as innate immunity in earthworms.

Structural basis for regulation of CELSR1 by a compact module in its extracellular region

The Cadherin EGF Laminin G seven-pass G-type receptor subfamily (CELSR/ADGRC) is one of the most conserved among adhesion G protein-coupled receptors and is essential for animal development. The extracellular regions (ECRs) of CELSRs are large with 23 adhesion domains. However, molecular insight into CELSR function is sparsely available. Here, we report the 3.8 Å cryo-EM reconstruction of the mouse CELSR1 ECR and reveal that 14 domains form a compact module mediated by conserved interactions majorly between the CADH9 and C-terminal GAIN domains. In the presence of Ca2+, the CELSR1 ECR forms a dimer species mediated by the cadherin repeats putatively in an antiparallel fashion. Cell-based assays reveal the N-terminal CADH1-8 repeat is required for cell-cell adhesion and the C-terminal CADH9-GAIN compact module can regulate cellular adhesion. Our work provides molecular insight into how one of the largest GPCRs uses defined structural modules to regulate receptor function.

Nanoscale Visualization of Drosophila E-cadherin Ectodomain Fragments and Their Interactions Using DNA Origami Nanoblocks

The adhesive function of cell surface proteins can be visually assessed through direct observation; however, the underlying structures that mediate adhesion typically remain invisible at the nanoscale level. This hinders knowledge on the diversity of molecular architectures responsible for cell-cell adhesion. Drosophila E-cadherin (DE-cadherin), a classical cadherin with a unique domain structure, demonstrates adhesive function; however, it lacks a structural model that explains its adhesion mechanism. Here, we present a novel application of DNA origami technology to create a cell-free, flat environment in which full DE-cadherin ectodomains are anchored using SNAP-tags and biotin-streptavidin interactions. DNA origami was assembled into a 120 nm long block, bearing 5 or 14 biotin:streptavidin sites that were evenly spaced on one lateral face. DE-cadherin ectodomain fragments were attached via biotinylated SNAP-tags. These decorated DNA origami nanoblocks were subjected to transmission electron and high-speed atomic force microscopy, which revealed a hinge-like site that separated the membrane-distal and -proximal portions of the DE-cadherin ectodomain, suggesting a role in mechanical flexibility. We also observed interactions between DE-cadherin ectodomains via their membrane-distal portions on single DNA origami nanoblocks. We reconstituted an adhesion-like process via pairing DNA origami nanoblocks using DE-cadherin ectodomain interactions. Homophilic associations of functional DE-cadherin ectodomains between the paired DNA origami nanoblocks were visualized at the nanoscale, displaying strand-like molecular configurations, likely representing the extracellular cadherin repeats without regular arrays of structural elements. This study introduces a DNA origami-based platform for reconstituting and visualizing cadherin ectodomain interactions, with potential applications for a broader range of adhesion molecules.

Identification of Amino Acid Residues Critical for the Interaction of Fibrin with N-Cadherin

We recently identified N-cadherin as a novel receptor for fibrin and localized complementary binding sites within the fibrin βN-domains and the third and fifth extracellular domains (EC3 and EC5) of N-cadherin. We also hypothesized that the His16 and Arg17 residues of the βN-domains and the (Asp/Glu)-X-(Asp/Glu) motifs present in the EC3 and EC5 domains may play roles in the interaction between fibrin and N-cadherin. The primary objectives of this study were to test these hypotheses and to further clarify the structural basis for this interaction. To test our hypotheses, we first mutated His16 and Arg17 in the recombinant (β15-66)2 fragment, which mimics the dimeric arrangement of the βN-domains in fibrin, using site-directed mutagenesis. The results revealed that the mutations of both His16 and Arg17 are critical for the interaction. Next, we mutated Asp/Glu residues in the three (Asp/Glu)-X-(Asp/Glu) motifs, M1 (Asp-Phe-Glu), M2 (Glu-Ala-Glu), and M3 (Asp-Tyr-Asp), of the fibrin-binding N-cad(3-5) fragment of N-cadherin. The results showed that Asp292 and Glu294 of M1, and Asp468 and Asp470 of M3, are critical for the interaction. Our molecular modeling of the 3D structure of the EC3-EC4-EC5 domains revealed that these residues are located at the interfaces of EC3-EC4 and EC4-EC5 and that some may also be involved in calcium binding. In conclusion, our study identified amino acid residues in the fibrin βN-domains and the EC3 and EC5 domains of N-cadherin that are critical for the interaction of fibrin with N-cadherin and localized the fibrin-binding residues in the 3D structure of N-cadherin.

Molecular Pathways Implicated in the Differentiation and Function of Epididymal Basal Cells

The postnatal development of the epididymis is a complex and poorly understood process. Our recent studies have shown that undifferentiated primitive small columnar cells are stem cells and can differentiate in vitro into basal and principal cells. This process represents a key aspect of early epididymal development. As such, the genes and signaling pathways implicated in the differentiation of stem cells are critical. In the rat, epididymal development has been subdivided into three phases consisting of an undifferentiated epithelium (birth to day 14), differentiation (days 14 to 44), and expansion (day 45 to adult). During this period, changes in gene expression in the epididymis are the most significant, as almost 1500 genes are differentially expressed between epididymides of 7 and 18 days of age. In the adult rat, basal cells appear to represent a quiescent adult stem cell population that can be cultured under 3D conditions and can differentiate into principal cells. Gene expression in basal cells of adults compared with epididymides from day 7 rats reveals approximately 400 genes that are common to both. Analyses of these genes predict multiple signaling pathways and master regulator genes. Their roles in early epididymal development suggest that the process is complex and involves multiple regulators, cell surface factors, signaling pathways, and hormones that are interconnected and which promote the differentiation of epididymal basal cells into other epididymal cell types.

Mutual adhesion of Lactobacillus spp. to intestinal cells: A review of perspectives on surface layer proteins and cell surface receptors

The bacterial ability to adhere and colonize in the gut is a key prerequisite to become a probiotic. Lactobacillus spp. surface layer proteins (SLPs) play an important role for such functions in the human body. Interestingly, all SLPs in spite of their structural variation promote adhesion and colonization. A clear understanding about the binding sites of SLPs with the host and their binding modes would help to precisely reveal the process of Lactobacillus spp.-host interaction. Therefore, in this paper, we have sorted out the Lactobacillus spp. SLPs and their adhesion sites in human intestinal cells. Such SLPs included surface layer protein, motif proteins, binding proteins and moonlighting proteins, while enterocyte adhesion receptors included transmembrane glycoproteins and extracellular matrix proteins. We also summarized the tools to assess the adhesion by Lactobacillus spp. Finally, we recommended that three-dimensional cell models and intestinal microarrays could be major tools for assessing adhesion in the future.

Classical cadherins evolutionary constraints in primates is associated with their expression in the central nervous system

Classical cadherins (CDH) comprise a family of single-pass transmembrane glycoproteins that contribute to tissue morphogenesis by regulating cell-cell adhesion, cytoskeletal dynamics, and cell signaling. CDH are grouped into type I (CDH 1, 2, 3, 4 and 15) and type II (CDH 5, 6, 7, 8, 9, 10, 11, 12, 18, 20, 22 and 24), based on the folding of the cadherin binding domain involved in trans-dimer formation. CDH are exclusively found in metazoans, and the origin and expansion of the gene family coincide with the emergence of multicellularity and vertebrates respectively. This study examined the evolutionary changes of CDH orthologs in primates and the factors that influence selective pressure to investigate the varying constraints exerted among CDH. Pairwise comparisons of the number of amino acid substitutions and of the ratio of non-synonymous substitutions per non-synonymous sites (dN) over synonymous substitutions per synonymous sites (dS), show that CDH2, CDH4, and most type II CDH have been under significantly higher negative selective pressure as compared to CDH1, CDH3, CDH5 and CDH19. Evaluation of gene essentiality as determined by the effect of germline deletion on animal viability, morphogenic phenotype, and reproductive fitness, show no correlation with the with extent of negative selection observed on CDH. Spearman's correlation analysis shows a positive correlation between CDH expression levels (E) in mouse and human tissues and their rate of evolution (R), as observed in most proteins expressed on the cell surface. However, CDH expression in the CNS show a significant E-R negative correlation, indicating that the strong negative selection exerted on CDH2, CDH4, and most type II CDH is associated with their expression in the CNS. CDH participate in a variety of cellular processes in the CNS including neuronal migration and functional assembly of neural circuits, which could profoundly influence animal fitness. Therefore, our findings suggest that the unusually high negative selective pressure exerted on CDH2, CDH4 and most type II CDH is due to their role in CNS formation and function and may have contributed to shape the evolution of the CNS in primates.

Neurotensin modulates ovarian vascular permeability via adherens junctions

Neurotensin (NTS) is a 13-amino acid peptide which is highly expressed in the mammalian ovary in response to the luteinizing hormone surge. Antibody neutralization of NTS in the ovulatory follicle of the cynomolgus macaque impairs ovulation and induces follicular vascular dysregulation, with excessive pooling of red blood cells in the follicle antrum. We hypothesize that NTS is an essential intrafollicular regulator of vascular permeability. In the present study, follicle injection of the NTS receptor antagonist SR142948 also resulted in vascular dysregulation. To measure vascular permeability changes in vitro, primary macaque ovarian microvascular endothelial cells (mOMECs) were enriched from follicle aspirates and studied in vitro. When treated with NTS, permeability of mOMECs decreased. RNA sequencing (RNA-Seq) of mOMECs revealed high mRNA expression of the permeability-regulating adherens junction proteins N-cadherin (CDH2) and K-cadherin (CDH6). Immunofluorescent detection of CDH2 and CDH6 confirmed expression and localized these cadherins to the cell-cell boundaries, consistent with function as components of adherens junctions. mOMECs did not express detectable levels of the typical vascular endothelial cadherin, VE-cadherin (CDH5) as determined by RNA-Seq, qPCR, western blot, and immunofluorescence. Knockdown of CDH2 or CDH6 via siRNA abrogated the NTS effect on mOMEC permeability. Collectively, these data suggest that NTS plays an ovulation-critical role in vascular permeability maintenance, and that CDH2 and CDH6 are involved in the permeability modulating effect of NTS on the ovarian microvasculature. NTS can be added to a growing number of angiogenic regulators which are critical for successful ovulation.

Structure of the extracellular region of the adhesion GPCR CELSR1 reveals a compact module which regulates G protein-coupling

Cadherin EGF Laminin G seven-pass G-type receptors (CELSRs or ADGRCs) are conserved adhesion G protein-coupled receptors which are essential for animal development. CELSRs have extracellular regions (ECRs) containing 23 adhesion domains which couple adhesion to intracellular signaling. However, molecular-level insight into CELSR function is sparsely available. We report the 4.3 Å cryo-EM reconstruction of the mCELSR1 ECR with 13 domains resolved in the structure. These domains form a compact module mediated by interdomain interactions with contact between the N- and C-terminal domains. We show the mCELSR1 ECR forms an extended species in the presence of Ca 2+ , which we propose represents the antiparallel cadherin repeat dimer. Using assays for adhesion and G protein-coupling, we assign the N-terminal CADH1-8 module as necessary for cell adhesion and we show the C-terminal CAHD9-GAIN module regulates signaling. Our work provides important molecular context to the literature on CELSR function and opens the door towards further mechanistic studies.

Identification of Neural (N)-Cadherin as a Novel Endothelial Cell Receptor for Fibrin and Localization of the Complementary Binding Sites

Based on the high structural homology between vascular endothelial (VE)-cadherin and neural (N)-cadherin, we hypothesized that fibrin, which is known to interact with VE-cadherin and promote angiogenesis through this interaction, may also interact with N-cadherin. To test this hypothesis, we prepared fibrin and its plasmin-produced and recombinant fragments covering practically all parts of the fibrin molecule. We also prepared the soluble extracellular portion of N-cadherin (sN-cadherin), which includes all five extracellular N-cadherin domains, and studied its interaction with fibrinogen, fibrin, and the aforementioned fibrin fragments using two independent methods, ELISA and SPR. The experiments confirmed our hypothesis, revealing that fibrin interacts with sN-cadherin with high affinity. Furthermore, the experiments localized the N-cadherin binding site within the fibrin βN-domains. Notably, the recombinant dimeric (β15-66)2 fragment, corresponding to these domains and mimicking their dimeric arrangement in fibrin, preserved the N-cadherin-binding properties of fibrin. To localize the fibrin binding site within N-cadherin, we performed ELISA and SPR experiments with (β15-66)2 and recombinant N-cadherin fragments representing its individual extracellular domains and combinations thereof. The results obtained indicate that the interaction of fibrin with N-cadherin occurs through the third and fifth extracellular domains of the latter. This is in contrast to our previous study, which revealed that fibrin interacts only with the third extracellular domain of VE-cadherin. In conclusion, our study identified N-cadherin as a novel receptor for fibrin and localized complementary binding sites within both fibrin and N-cadherin. The pathophysiological role of this interaction remains to be established.

Structural basis of molecular recognition among classical cadherins mediating cell adhesion

Cadherins are type-I membrane glycoproteins that primarily participate in calcium-dependent cell adhesion and homotypic cell sorting in various stages of embryonic development. Besides their crucial role in cellular and physiological processes, increasing studies highlight their involvement in pathophysiological functions ranging from cancer progression and metastasis to being entry receptors for pathogens. Cadherins mediate these cellular processes through homophilic, as well as heterophilic interactions (within and outside the superfamily) by their membrane distal ectodomains. This review provides an in-depth structural perspective of molecular recognition among type-I and type-II classical cadherins. Furthermore, this review offers structural insights into different dimeric assemblies like the 'strand-swap dimer' and 'X-dimer' as well as mechanisms relating these dimer forms like 'two-step adhesion' and 'encounter complex'. Alongside providing structural details, this review connects structural studies to bond mechanics merging crystallographic and single-molecule force spectroscopic findings. Finally, the review discusses the recent discoveries on dimeric intermediates that uncover prospects of further research beyond two-step adhesion.

Epigenetic regulation in lung cancer

Lung cancer is indeed a major cause of cancer-related deaths worldwide. The development of tumors involves a complex interplay of genetic, epigenetic, and environmental factors. Epigenetic mechanisms, including DNA methylation (DNAm), histone modifications, and microRNA expression, play a crucial role in this process. Changes in DNAm patterns can lead to the silencing of important genes involved in cellular functions, contributing to the development and progression of lung cancer. MicroRNAs and exosomes have also emerged as reliable biomarkers for lung cancer. They can provide valuable information about early diagnosis and treatment assessment. In particular, abnormal hypermethylation of gene promoters and its effects on tumorigenesis, as well as its roles in the Wnt signaling pathway, have been extensively studied. Epigenetic drugs have shown promise in the treatment of lung cancer. These drugs target the aberrant epigenetic modifications that are involved in the development and progression of the disease. Several factors have been identified as drug targets in non-small cell lung cancer. Recently, combination therapy has been discussed as a successful strategy for overcoming drug resistance. Overall, understanding the role of epigenetic mechanisms and their targeting through drugs is an important area of research in lung cancer treatment.

LY6/PLAUR domain containing 3 (LYPD3) maintains melanoma cell stemness and mediates an immunosuppressive microenvironment

BACKGROUND

Malignant melanoma is a highly heterogeneous skin cancer with the highest mortality rate among dermatological cancers. Catenins form functional networks in the nucleus to regulate gene expression and determine cell fate. Dysregulation of catenin expression correlates with the malignant characteristics of the tumor. We aimed to investigate the regulatory mechanisms of catenins in melanoma and to further define the function of catenin-related molecular signaling in the tumor microenvironment.

METHODS

In this study, a bioinformatics approach combined with experimental validation was used to explore the potential tumor biology mechanisms of catenin-related signaling.

RESULTS

Melanoma patients can be divided into two catenin clusters. Patients defined by high Junction Plakoglobin (JUP), Plakophilin 1 (PKP1), Plakophilin 3 (PKP3) levels (C2) had shorter survival time than other patients (C1). We demonstrated that JUP regulates Anterior Gradient 2 (AGR2)/LY6/PLAUR Domain Containing 3 (LYPD3) to maintain melanoma stemness and promotes glycolysis. We also found that LYPD3 was co-expressed with S100A9 and associated with immunosuppressive tumor microenvironment (TME).

CONCLUSION

The JUP/AGR2/LYPD3 signaling axis plays an important role in the malignant features of melanoma. Targeting the JUP/AGR2/LYPD3 signaling axis can help develop promising drugs.

Classical cadherins in the testis: how are they regulated?

Cadherins (CDH) are crucial intercellular adhesion molecules, contributing to morphogenesis and creating tissue barriers by regulating cells' movement, clustering and differentiation. In the testis, classical cadherins such as CDH1, CDH2 and CDH3 are critical to gonadogenesis by promoting the migration and the subsequent clustering of primordial germ cells with somatic cells. While CDH2 is present in both Sertoli and germ cells in rodents, CDH1 is primarily detected in undifferentiated spermatogonia. As for CDH3, its expression is mainly found in germ and pre-Sertoli cells in developing gonads until the establishment of the blood-testis barrier (BTB). This barrier is made of Sertoli cells forming intercellular junctional complexes. The restructuring of the BTB allows the movement of early spermatocytes toward the apical compartment as they differentiate during a process called spermatogenesis. CDH2 is among many junctional proteins participating in this process and is regulated by several pathways. While cytokines promote the disassembly of the BTB by enhancing junctional protein endocytosis for degradation, testosterone facilitates the assembly of the BTB by increasing the recycling of endocytosed junctional proteins. Mitogen-activated protein kinases (MAPKs) are also mediators of the BTB kinetics in many chemically induced damages in the testis. In addition to regulating Sertoli cell functions, follicle stimulating hormone can also regulate the expression of CDH2. In this review, we discuss the current knowledge on regulatory mechanisms of cadherin localisation and expression in the testis.

Expect the unexpected: conventional and unconventional roles for cadherins in collective cell migration

Migrating cell collectives navigate complex tissue environments both during normal development and in pathological contexts such as tumor invasion and metastasis. To do this, cells in collectives must stay together but also communicate information across the group. The cadherin superfamily of proteins mediates junctional adhesions between cells, but also serve many essential functions in collective cell migration. Besides keeping migrating cell collectives cohesive, cadherins help follower cells maintain their attachment to leader cells, transfer information about front-rear polarity among the cohort, sense and respond to changes in the tissue environment, and promote intracellular signaling, in addition to other cellular behaviors. In this review, we highlight recent studies that reveal diverse but critical roles for both classical and atypical cadherins in collective cell migration, specifically focusing on four in vivo model systems in development: the Drosophila border cells, zebrafish mesendodermal cells, Drosophila follicle rotation, and Xenopus neural crest cells.

Protocadherin 20 maintains intestinal barrier function to protect against Crohn's disease by targeting ATF6

BACKGROUND

Intestinal barrier dysfunction plays a central role in the pathological onset of Crohn's disease. We identify the cadherin superfamily member protocadherin 20 (PCDH20) as a crucial factor in Crohn's disease. Here we describe the function of PCDH20 and its mechanisms in gut homeostasis, barrier integrity, and Crohn's disease development.

RESULTS

PCDH20 mRNA and protein expression is significantly downregulated in the colonic epithelium of Crohn's disease patients and mice with induced colitis compared with controls. In mice, intestinal-specific Pcdh20 knockout causes defects in enterocyte proliferation and differentiation, while causing morphological abnormalities. Specifically, the deletion disrupts barrier integrity by unzipping adherens junctions via β-catenin regulation and p120-catenin phosphorylation, thus aggravating colitis in DSS- and TNBS-induced colitis mouse models. Furthermore, we identify activating transcription factor 6 (ATF6), a key chaperone of endoplasmic reticulum stress, as a functional downstream effector of PCDH20. By administering a selective ATF6 activator, the impairment of intestinal barrier integrity and dysregulation of CHOP/β-catenin/p-p120-catenin pathway was reversed in Pcdh20-ablated mice with colitis and PCDH20-deficient colonic cell lines.

CONCLUSIONS

PCDH20 is an essential factor in maintaining intestinal epithelial homeostasis and barrier integrity. Specifically, PCDH20 helps to protect against colitis by tightening adherens junctions through the ATF6/CHOP/β-catenin/p-p120-catenin axis.

The computational capabilities of many-to-many protein interaction networks

Many biological circuits comprise sets of protein variants that interact with one another in a many-to-many, or promiscuous, fashion. These architectures can provide powerful computational capabilities that are especially critical in multicellular organisms. Understanding the principles of biochemical computations in these circuits could allow more precise control of cellular behaviors. However, these systems are inherently difficult to analyze, due to their large number of interacting molecular components, partial redundancies, and cell context dependence. Here, we discuss recent experimental and theoretical advances that are beginning to reveal how promiscuous circuits compute, what roles those computations play in natural biological contexts, and how promiscuous architectures can be applied for the design of synthetic multicellular behaviors.

Paritaprevir ameliorates experimental acute lung injury in vitro and in vivo

Paritaprevir is a potent inhibitor of the NS3/4A protease used to treat chronic hepatitis C virus infection. However, its therapeutic effect on acute lung injury (ALI) remains to be elucidated. In this study, we investigated the effect of paritaprevir on a lipopolysaccharide (LPS)-induced two-hit rat ALI model. The anti-ALI mechanism of paritaprevir was also studied in human pulmonary microvascular endothelial (HM) cells following LPS-induced injury in vitro. Administration of 30 mg/kg paritaprevir for 3 days protected rats from LPS-induced ALI, as reflected by the changes in the lung coefficient (from 0.75 to 0.64) and lung pathology scores (from 5.17 to 5.20). Furthermore, the levels of the protective adhesion protein VE-cadherin and tight junction protein claudin-5 increased, and the cytoplasmic p-FOX-O1 and nuclear β-catenin and FOX-O1 levels decreased. Similar effects were observed in vitro with LPS-treated HM cells, including decreased nuclear β-catenin and FOX-O1 levels and higher VE-cadherin and claudin-5 levels. Moreover, β-catenin inhibition resulted in higher p-FOX-O1 levels in the cytoplasm. These results suggested that paritaprevir could alleviate experimental ALI via the β-catenin/p-Akt/ FOX-O1 signaling pathway.

IgGFc-binding protein and MUC2 mucin produced by colonic goblet-like cells spatially interact non-covalently and regulate wound healing

The colonic mucus bilayer is the first line of innate host defense that at the same time houses and nourishes the commensal microbiota. The major components of mucus secreted by goblet cells are MUC2 mucin and the mucus-associated protein, FCGBP (IgGFc-binding protein). In this study, we determine if FCGBP and MUC2 mucin were biosynthesized and interacted together to spatially enhance the structural integrity of secreted mucus and its role in epithelial barrier function. MUC2 and FCGBP were coordinately regulated temporally in goblet-like cells and in response to a mucus secretagogue but not in CRISPR-Cas9 gene-edited MUC2 KO cells. Whereas ~85% of MUC2 was colocalized with FCGBP in mucin granules, ~50% of FCGBP was diffusely distributed in the cytoplasm of goblet-like cells. STRING-db v11 analysis of the mucin granule proteome revealed no protein-protein interaction between MUC2 and FCGBP. However, FCGBP interacted with other mucus-associated proteins. FCGBP and MUC2 interacted via N-linked glycans and were non-covalently bound in secreted mucus with cleaved low molecular weight FCGBP fragments. In MUC2 KO, cytoplasmic FCGBP was significantly increased and diffusely distributed in wounded cells that healed by enhanced proliferation and migration within 2 days, whereas, in WT cells, MUC2 and FCGBP were highly polarized at the wound margin which impeded wound closure by 6 days. In DSS colitis, restitution and healed lesions in Muc2^+/+ but not Muc2^-/- littermates, were accompanied by a rapid increase in Fcgbp mRNA and delayed protein expression at 12- and 15-days post DSS, implicating a potential novel endogenous protective role for FCGBP in wound healing to maintain epithelial barrier function.

Interacting bactofilins impact cell shape of the MreB-less multicellular Rhodomicrobium vannielii

Most non-spherical bacteria rely on the actin-like MreB cytoskeleton to control synthesis of a cell-shaping and primarily rod-like cell wall. Diverging from simple rod shape generally requires accessory cytoskeletal elements, which locally interfere with the MreB-guided cell wall synthesis. Conserved and widespread representatives of this accessory cytoskeleton are bactofilins that polymerize into static, non-polar bundles of filaments. Intriguingly, many species of the Actinobacteria and Rhizobiales manage to grow rod-like without MreB by tip extension, yet some of them still possess bactofilin genes, whose function in cell morphogenesis is unknown. An intricate representative of these tip-growing bacteria is Rhodomicrobium vannielii; a member of the hitherto genetically not tractable and poorly studied Hyphomicrobiaceae within the MreB-less Rhizobiales order. R. vannielii displays complex asymmetric cell shapes and differentiation patterns including filamentous hyphae to produce offspring and to build dendritic multicellular arrays. Here, we introduce techniques to genetically access R. vannielii, and we elucidate the role of bactofilins in its sophisticated morphogenesis. By targeted mutagenesis and fluorescence microscopy, protein interaction studies and peptidoglycan incorporation analysis we show that the R. vannielii bactofilins are associated with the hyphal growth zones and that one of them is essential to form proper hyphae. Another paralog is suggested to represent a novel hybrid and co-polymerizing bactofilin. Notably, we present R. vannielii as a powerful new model to understand prokaryotic cell development and control of multipolar cell growth in the absence of the conserved cytoskeletal element, MreB.

Chemical factors induce aggregative multicellularity in a close unicellular relative of animals

Regulated cellular aggregation is an essential process for development and healing in many animal tissues. In some animals and a few distantly related unicellular species, cellular aggregation is regulated by diffusible chemical cues. However, it is unclear whether regulated cellular aggregation was part of the life cycles of the first multicellular animals and/or their unicellular ancestors. To fill this gap, we investigated the triggers of cellular aggregation in one of animals' closest unicellular living relatives-the filasterean Capsaspora owczarzaki. We discovered that Capsaspora aggregation is induced by chemical cues, as observed in some of the earliest branching animals and other unicellular species. Specifically, we found that calcium ions and lipids present in lipoproteins function together to induce aggregation of viable Capsaspora cells. We also found that this multicellular stage is reversible as depletion of the cues triggers disaggregation, which can be overcome upon reinduction. Our finding demonstrates that chemically regulated aggregation is important across diverse members of the holozoan clade. Therefore, this phenotype was plausibly integral to the life cycles of the unicellular ancestors of animals.

Antiparallel dimer structure of CELSR cadherin in solution revealed by high-speed atomic force microscopy

Cadherin EGF LAG seven-pass G-type receptors (CELSR) cadherins, members of the cadherin superfamily, and adhesion G-protein-coupled receptors, play a vital role in cell-cell adhesion. The mutual binding of the extracellular domains (ectodomains) of CELSR cadherins between cells is crucial for tissue formation, including the establishment of planar cell polarity, which directs the proper patterning of cells. CELSR cadherins possess nine cadherin ectodomains (EC1-EC9) and noncadherin ectodomains. However, the structural and functional mechanisms of the binding mode of CELSR cadherins have not been determined. In this study, we investigated the binding mode of CELSR cadherins using single-molecule fluorescence microscopy, high-speed atomic force microscopy (HS-AFM), and bead aggregation assay. The fluorescence microscopy analysis results indicated that the trans-dimer of the CELSR cadherin constitutes the essential adhesive unit between cells. HS-AFM analysis and bead aggregation assay results demonstrated that EC1-EC8 entirely overlap and twist to form antiparallel dimer conformations and that the binding of EC1-EC4 is sufficient to sustain bead aggregation. The interaction mechanism of CELSR cadherin may elucidate the variation of the binding mechanism within the cadherin superfamily and physiological role of CELSR cadherins in relation to planar cell polarity.

Kazrin promotes dynein/dynactin-dependent traffic from early to recycling endosomes

Kazrin is a protein widely expressed in vertebrates whose depletion causes a myriad of developmental defects, in part derived from altered cell adhesion and migration, as well as failure to undergo epidermal to mesenchymal transition. However, the primary molecular role of kazrin, which might contribute to all these functions, has not been elucidated yet. We previously identified one of its isoforms, kazrin C, as a protein that potently inhibits clathrin-mediated endocytosis when overexpressed. We now generated kazrin knock-out mouse embryonic fibroblasts to investigate its endocytic function. We found that kazrin depletion delays juxtanuclear enrichment of internalized material, indicating a role in endocytic traffic from early to recycling endosomes. Consistently, we found that the C-terminal domain of kazrin C, predicted to be an intrinsically disordered region, directly interacts with several early endosome (EE) components, and that kazrin depletion impairs retrograde motility of these organelles. Further, we noticed that the N-terminus of kazrin C shares homology with dynein/dynactin adaptors and that it directly interacts with the dynactin complex and the dynein light intermediate chain 1. Altogether, the data indicate that one of the primary kazrin functions is to facilitate endocytic recycling by promoting dynein/dynactin-dependent transport of EEs or EE-derived transport intermediates to the recycling endosomes.

Proteomics of the dentate gyrus reveals semantic dementia specific molecular pathology

Semantic dementia (SD) is a clinical subtype of frontotemporal dementia consistent with the neuropathological diagnosis frontotemporal lobar degeneration (FTLD) TDP type C, with characteristic round TDP-43 protein inclusions in the dentate gyrus. Despite this striking clinicopathological concordance, the pathogenic mechanisms are largely unexplained forestalling the development of targeted therapeutics. To address this, we carried out laser capture microdissection of the dentate gyrus of 15 SD patients and 17 non-demented controls, and assessed relative protein abundance changes by label-free quantitative mass spectrometry. To identify SD specific proteins, we compared our results to eight other FTLD and Alzheimer's disease (AD) proteomic datasets of cortical brain tissue, parallel with functional enrichment analyses and protein-protein interactions (PPI). Of the total 5,354 quantified proteins, 151 showed differential abundance in SD patients (adjusted P-value < 0.01). Seventy-nine proteins were considered potentially SD specific as these were not detected, or demonstrated insignificant or opposite change in FTLD/AD. Functional enrichment indicated an overrepresentation of pathways related to the immune response, metabolic processes, and cell-junction assembly. PPI analysis highlighted a cluster of interacting proteins associated with adherens junction and cadherin binding, the cadherin-catenin complex. Multiple proteins in this complex showed significant upregulation in SD, including β-catenin (CTNNB1), γ-catenin (JUP), and N-cadherin (CDH2), which were not observed in other neurodegenerative proteomic studies, and hence may resemble SD specific involvement. A trend of upregulation of all three proteins was observed by immunoblotting of whole hippocampus tissue, albeit only significant for N-cadherin. In summary, we discovered a specific increase of cell adhesion proteins in SD constituting the cadherin-catenin complex at the synaptic membrane, essential for synaptic signaling. Although further investigation and validation are warranted, we anticipate that these findings will help unravel the disease processes underlying SD.

Cell polarity signalling at the birth of multicellularity: What can we learn from the first animals

The innovation of multicellularity has driven the unparalleled evolution of animals (Metazoa). But how is a multicellular organism formed and how is its architecture maintained faithfully? The defining properties and rules required for the establishment of the architecture of multicellular organisms include the development of adhesive cell interactions, orientation of division axis, and the ability to reposition daughter cells over long distances. Central to all these properties is the ability to generate asymmetry (polarity), coordinated by a highly conserved set of proteins known as cell polarity regulators. The cell polarity complexes, Scribble, Par and Crumbs, are considered to be a metazoan innovation with apicobasal polarity and adherens junctions both believed to be present in all animals. A better understanding of the fundamental mechanisms regulating cell polarity and tissue architecture should provide key insights into the development and regeneration of all animals including humans. Here we review what is currently known about cell polarity and its control in the most basal metazoans, and how these first examples of multicellular life can inform us about the core mechanisms of tissue organisation and repair, and ultimately diseases of tissue organisation, such as cancer.

Cell sorting in vitro and in vivo: How are cadherins involved?

Animal tissues are composed of heterogenous cells, and their sorting into different compartments of the tissue is a pivotal process for organogenesis. Cells accomplish sorting by themselves-it is well known that singly dispersed cells can self-organize into tissue-like structures in vitro. Cell sorting is regulated by both biochemical and physical mechanisms. Adhesive proteins connect cells together, selecting particular partners through their specific binding properties, while physical forces, such as cell-cortical tension, control the cohesiveness between cells and in turn cell assembly patterns in mechanical ways. These processes cooperate in determining the overall cell sorting behavior. This article focuses on the 'cadherin' family of adhesion molecules as a biochemical component of cell-cell interactions, addressing how they regulate cell sorting by themselves or by cooperating with other factors. New ideas beyond the classical models of cell sorting are also discussed.

A Common Variant in the CDK8 Gene Is Associated with Sporadic Pituitary Adenomas in the Portuguese Population: A Case-Control Study

The majority of pituitary adenomas occur in a sporadic context, and in the absence of known genetic predisposition. Three common variants at the NEBL (rs2359536), PCDH15 (rs10763170) and CDK8 (rs17083838) loci were previously associated with sporadic pituitary adenomas in the Han Chinese population, but these findings have not yet been replicated in any other population. The aim of this case-control study was to assess if these variants are associated with susceptibility to sporadic pituitary adenomas in the Portuguese population. Genotype and allele frequencies were determined in 570 cases and in 546 controls. The CDK8 rs17083838 minor allele (A allele) was significantly associated with sporadic pituitary adenomas, under an additive (odds ratio (OR) 1.73, 95% confidence interval (CI) 1.19–2.50, p = 0.004) and dominant (OR 1.82, 95% CI 1.24–2.68, p = 0.002) inheritance model. The NEBL rs2359536 and PCDH15 rs10763170 variants were not associated with the overall risk for the disease, although a borderline significant association was observed between the PCDH15 rs10763170 minor allele (T allele) and somatotrophinomas (dominant model, OR 1.55, 95% CI 1.02–2.35, p = 0.035). These findings suggest that the CDK8 rs17083838 variant, and possibly the PCDH15 rs10763170 variant, may increase susceptibility to sporadic pituitary adenomas in the Portuguese population.

Protocadherin Gamma C3 (PCDHGC3) Is Strongly Expressed in Glioblastoma and Its High Expression Is Associated with Longer Progression-Free Survival of Patients

Protocadherins (PCDHs) belong to the cadherin superfamily and represent the largest subgroup of calcium-dependent adhesion molecules. In the genome, most PCDHs are arranged in three clusters, α, β, and γ on chromosome 5q31. PCDHs are highly expressed in the central nervous system (CNS). Several PCDHs have tumor suppressor functions, but their individual role in primary brain tumors has not yet been elucidated. Here, we examined the mRNA expression of PCDHGC3, a member of the PCDHγ cluster, in non-cancerous brain tissue and in gliomas of different World Health Organization (WHO) grades and correlated it with the clinical data of the patients. We generated a PCDHGC3 knockout U343 cell line and examined its growth rate and migration in a wound healing assay. We showed that PCDHGC3 mRNA and protein were significantly overexpressed in glioma tissue compared to a non-cancerous brain specimen. This could be confirmed in glioma cell lines. High PCDHGC3 mRNA expression correlated with longer progression-free survival (PFS) in glioma patients. PCDHGC3 knockout in U343 resulted in a slower growth rate but a significantly faster migration rate in the wound healing assay and decreased the expression of several genes involved in WNT signaling. PCDHGC3 expression should therefore be further investigated as a PFS-marker in gliomas. However, more studies are needed to elucidate the molecular mechanisms underlying the PCDHGC3 effects.

β-cells retain a pool of insulin-containing secretory vesicles regulated by adherens junctions and the cadherin binding protein p120 catenin

The β-cells of the islets of Langerhans are the sole producers of insulin in the human body. In response to rising glucose levels, insulin-containing vesicles inside β-cells fuse with the plasma membrane and release their cargo. However, the mechanisms regulating this process are only partly understood. Previous evidence indicated reductions in α-catenin elevate insulin release, while reductions in β-catenin decrease insulin release. α- and β-catenin contribute to cellular regulation in a range of ways but one is as members of the adherens junction complex and these contribute to the development of cell polarity in b-cells. Therefore, we investigated the effects of adherens junctions on insulin release. We show in INS-1E β-cells knockdown of either E- or N-cadherin had only small effects on insulin secretion, but simultaneous knockout of both cadherins resulted in a significant increase in basal insulin release to the same level as glucose-stimulated release. This double knockdown also significantly attenuated levels of p120 catenin, a cadherin binding partner involved in regulating cadherin turnover. Conversely, reducing p120 catenin levels with siRNA destabilized both E- and N-cadherin, and this was also associated with an increase in levels of insulin secreted from INS-1E cells. Furthermore, there were also changes in these cells consistent with higher insulin release, namely reductions in levels of F-actin and increased intracellular free Ca²⁺ levels in response to KCl-induced membrane depolarization. Taken together, these data provide evidence that adherens junctions play important roles in retaining a pool of insulin secretory vesicles within the cell and establish a role for p120 catenin in regulating this process.

Role of CDH23 as a prognostic biomarker and its relationship with immune infiltration in acute myeloid leukemia

Background

Cadherin-23 (CDH23) plays an important role in intercellular adhesion and is involved in the progression of several types of cancer. However, the biological functions and effect of CDH23 expression on the prognosis of patients with acute myeloid leukemia (AML) are unexplored. Herein, we aim to characterize the role and molecular functions of CDH23 in AML.

Methods

We downloaded the transcriptomic profiles and clinical data from the Cancer Genome Atlas and Beat AML trial. The expression level of CDH23 was assessed using Gene Expression Profiling Interactive Analysis (GEPIA). Kaplan-Meier survival analysis was used to assess prognostic value of CDH23. Correlation and biological function analyses were performed using LinkedOmics and GeneMANIA. Relationship of CDH23 with immune infiltration level was determined using Tumor Immune Estimation Resource (TIMER).

Results

We found that the CDH23 expression was aberrantly upregulated in patients with AML and could be used as an independent risk factor of overall survival using Cox multivariate analysis. Notably, we observed a negative correlation between CDH23 expression and immune cell infiltration abundance by calculating the immune and stromal scores. In addition, functional enrichment analysis established that CDH23 plays a crucial role in tumor immunity.

Conclusions

Our findings indicate that upregulated CDH23 expression corresponds to decreased overall survival of patients with AML. CDH23 may be involved in mediating tumor immune environment, and this highlights the potential of CDH23 as a therapeutic target in AML.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-022-09532-1.

Emerging Cnidarian Models for the Study of Epithelial Polarity

Epithelial tissues are vital to the function of most organs, providing critical functions such as secretion, protection, and absorption. Cells within an epithelial layer must coordinate to create functionally distinct apical, lateral, and basal surfaces in order to maintain proper organ function and organism viability. This is accomplished through the careful targeting of polarity factors to their respective locations within the cell, as well as the strategic placement of post-mitotic cells within the epithelium during tissue morphogenesis. The process of establishing and maintaining epithelial tissue integrity is conserved across many species, as important polarity factors and spindle orientation mechanisms can be found in many phyla. However, most of the information gathered about these processes and players has been investigated in bilaterian organisms such as C. elegans, Drosophila, and vertebrate species. This review discusses the advances made in the field of epithelial polarity establishment from more basal organisms, and the advantages to utilizing these simpler models. An increasing number of cnidarian model organisms have been sequenced in recent years, such as Hydra vulgaris and Nematostella vectensis. It is now feasible to investigate how polarity is established and maintained in basal organisms to gain an understanding of the most basal requirements for epithelial tissue morphogenesis.

Elastic versus brittle mechanical responses predicted for dimeric cadherin complexes

Cadherins are a superfamily of adhesion proteins involved in a variety of biological processes that include the formation of intercellular contacts, the maintenance of tissue integrity, and the development of neuronal circuits. These transmembrane proteins are characterized by ectodomains composed of a variable number of extracellular cadherin (EC) repeats that are similar but not identical in sequence and fold. E-cadherin, along with desmoglein and desmocollin proteins, are three classical-type cadherins that have slightly curved ectodomains and engage in homophilic and heterophilic interactions through an exchange of conserved tryptophan residues in their N-terminal EC1 repeat. In contrast, clustered protocadherins are straighter than classical cadherins and interact through an antiparallel homophilic binding interface that involves overlapped EC1 to EC4 repeats. Here we present molecular dynamics simulations that model the adhesive domains of these cadherins using available crystal structures, with systems encompassing up to 2.8 million atoms. Simulations of complete classical cadherin ectodomain dimers predict a two-phased elastic response to force in which these complexes first softly unbend and then stiffen to unbind without unfolding. Simulated α, β, and γ clustered protocadherin homodimers lack a two-phased elastic response, are brittle and stiffer than classical cadherins and exhibit complex unbinding pathways that in some cases involve transient intermediates. We propose that these distinct mechanical responses are important for function, with classical cadherin ectodomains acting as molecular shock absorbers and with stiffer clustered protocadherin ectodomains facilitating overlap that favors binding specificity over mechanical resilience. Overall, our simulations provide insights into the molecular mechanics of single cadherin dimers relevant in the formation of cellular junctions essential for tissue function.

Potential Therapeutic Applications of N-Cadherin Antagonists and Agonists

This review focuses on the cell adhesion molecule (CAM), known as neural (N)-cadherin (CDH2). The molecular basis of N-cadherin-mediated intercellular adhesion is discussed, as well as the intracellular signaling pathways regulated by this CAM. N-cadherin antagonists and agonists are then described, and several potential therapeutic applications of these intercellular adhesion modulators are considered. The usefulness of N-cadherin antagonists in treating fibrotic diseases and cancer, as well as manipulating vascular function are emphasized. Biomaterials incorporating N-cadherin modulators for tissue regeneration are also presented. N-cadherin antagonists and agonists have potential for broad utility in the treatment of numerous maladies.

Origin and Evolution of the Multifaceted Adherens Junction Component Plekha7

Plekha7 is a key adherens junction component involved in numerous functions in mammalian cells. Plekha7 is the most studied member of the PLEKHA protein family, which includes eight members with diverse functions. However, the evolutionary history of Plekha7 remains unexplored. Here, we outline the phylogeny and identify the origins of this gene and its paralogs. We show that Plekha7, together with Plekha4, Plekha5, and Plekha6, belong to a subfamily that we name PLEKHA4/5/6/7. This subfamily is distinct from the other Plekha proteins, which form two additional separate subfamilies, namely PLEKHA1/2 and PLEKHA3/8. Sequence, phylogenetic, exon-intron organization, and syntenic analyses reveal that the PLEKHA4/5/6/7 subfamily is represented by a single gene in invertebrates, which remained single in the last common ancestor of all chordates and underwent gene duplications distinctly in jawless and jawed vertebrates. In the latter species, a first round of gene duplications gave rise to the Plekha4/7 and Plekha5/6 pairs and a second round to the four extant members of the subfamily. These observations are consistent with the 1R/2R hypothesis of vertebrate genome evolution. Plekha7 and Plekha5 also exist in two copies in ray-finned fishes, due to the Teleostei-specific whole genome duplication. Similarities between the vertebrate Plekha4/5/6/7 members and non-chordate sequences are restricted to their N-terminal PH domains, whereas similarities across the remaining protein molecule are only sporadically found among few invertebrate species and are limited to the coiled-coil and extreme C-terminal ends. The vertebrate Plekha4/5/6/7 proteins contain extensive intrinsically disordered domains, which are topologically and structurally conserved in all chordates, but not in non-chordate invertebrates. In summary, our study sheds light on the origins and evolution of Plekha7 and the PLEKHA4/5/6/7 subfamily and unveils new critical information suitable for future functional studies of this still understudied group of proteins.

PFOI stimulates the motility of T24 bladder cancer cells: Possible involvement and activation of lncRNA malat1

Perfluorinated iodine alkanes (PFIs) can serve as an important raw materials for the synthesis of various perfluorinated chemical products through telomerization reaction. The estrogenic effects of PFIs have been reported previously by some in vitro and in vivo screening assays. To explore the potential epigenetic toxicity of PFIs, activation of lncRNAs was screened, and the cell motility changes induced by perfluorooctyl iodide (PFOI) were analyzed in this study. High metastatic bladder cell line (T24) was used to investigate the cellular migration function affected by PFOI. PFOI exposure significantly induced the upregulation of lncRNA anril, thorlnc, hotairm1, meg3, and malat1. The migration and invasion of T24 cells were also enhanced upon PFOI exposure. The transcription level of matrix metalloenzyme genes, epidermal growth factors, cytoskeleton genes, and the upstream factors involved in cell motility pathways were examined to illustrate possible mechanisms. Additionally, the basic role of malat1 in cellular motility was investigated by lncRNA knockdown and migration assays. The knockdown of malat1 inhibited the cellular motility induced by PFOI. The levels of MMP-2/-9 genes were also down-regulated by the treatment of si-malat1. Overall, the perturbation of cytoskeleton genes (E-cadherin/N-cadherin) may account for the impact on the motility of T24 cells. Our studies indicate that perfluorinated chemicals might regulate the lncRNAs, thus promoting the metastasis of the tumor cells.

Mesalazine initiates an anti-oncogenic β-catenin / MUCDHL negative feed-back loop in colon cancer cells by cell-specific mechanisms

Chronic inflammation associated with intestinal architecture and barrier disruption puts patients with inflammatory bowel disease (IBD) at increased risk of developing colorectal cancer (CRC). Widely used to reduce flares of intestinal inflammation, 5-aminosalicylic acid derivatives (5-ASAs) such as mesalazine appear to also exert more direct mucosal healing and chemopreventive activities against CRC. The mechanisms underlying these activities are poorly understood and may involve the up-regulation of the cadherin-related gene MUCDHL (CDHR5). This atypical cadherin is emerging as a new actor of intestinal homeostasis and opposes colon tumorigenesis. Here, we showed that mesalazine increase mRNA levels of MUCDHL and of other genes involved in the intestinal barrier function in most intestinal cell lines. In addition, using gain / loss of function experiments (agonists, plasmid or siRNAs transfections), luciferase reporter genes and chromatin immunoprecipitation, we thoroughly investigated the molecular mechanisms triggered by mesalazine that lead to the up-regulation of MUCDHL expression. We found that basal transcription of MUCDHL in different CRC cell lines is regulated positively by CDX2 and negatively by β-catenin through a negative feed-back loop. However, mesalazine-stimulation of MUCDHL transcription is controlled by cell-specific mechanisms, involving either enhanced activation of CDX2 and PPAR-γ or repression of the β-catenin inhibitory effect. This work highlights the importance of the cellular and molecular context in the activity of mesalazine and suggests that its efficacy against CRC depends on the genetic alterations of transformed cells.

Cadherin-12 Regulates Neurite Outgrowth Through the PKA/Rac1/Cdc42 Pathway in Cortical Neurons

Cadherins play an important role in tissue homeostasis, as they are responsible for cell-cell adhesion during embryogenesis, tissue morphogenesis, and differentiation. In this study, we identified Cadherin-12 (CDH12), which encodes a type II classical cadherin, as a gene that promotes neurite outgrowth in an in vitro model of neurons with differentiated intrinsic growth ability. First, the effects of CDH12 on neurons were evaluated via RNA interference, and the results indicated that the knockdown of CDH12 expression restrained the axon extension of E18 neurons. The transcriptome profile of neurons with or without siCDH12 treatment revealed a set of pathways positively correlated with the effect of CDH12 on neurite outgrowth. We further revealed that CDH12 affected Rac1/Cdc42 phosphorylation in a PKA-dependent manner after testing using H-89 and 8-Bromo-cAMP sodium salt. Moreover, we investigated the expression of CDH12 in the brain, spinal cord, and dorsal root ganglia (DRG) during development using immunofluorescence staining. After that, we explored the effects of CDH12 on neurite outgrowth in vivo. A zebrafish model of CDH12 knockdown was established using the NgAgo-gDNA system, and the vital role of CDH12 in peripheral neurogenesis was determined. In summary, our study is the first to report the effect of CDH12 on axonal extension in vitro and in vivo, and we provide a preliminary explanation for this mechanism.

MicroRNA-200c/429 mediated regulation of Zeb1 augments N-Cadherin in mouse cardiac mesenchymal cells

Cardiac mesenchymal cells (CMCs) are a promising cell type that showed therapeutic potential in heart failure models. The analysis of the underlying mechanisms by which the CMCs improve cardiac function is on track. This study aimed to investigate the expression of N-Cadherin, a transmembrane protein that enhances cell adhesion, and recently gained attention for differentiation and augmentation of stem cell function. The mouse CMCs were isolated and analyzed for the mesenchymal markers using flow cytometry. Quantitative real-time polymerase chain reaction (qRT-PCR) and western blot analysis were used to assess the expression of N-Cadherin along with its counteracting molecule E-Cadherin and their regulator Zeb1 in CMCs and dermal fibroblast. The expression level of miR-200c and miR-429 was analyzed using miRNA assays. Transient transfection of miR-200c followed by qRT-PCR, western blot analysis, and immunostaining was done in CMCs to analyze the expression of Zeb1, N-Cadherin, and E-Cadherin. Flow cytometry analysis showed that CMCs possess mesenchymal markers and absence for hematopoietic and immune cell markers. Increased expression of N-Cadherin and Zeb1 in CMCs was observed in CMCs at both RNA and protein levels compared to fibroblast. We found significant downregulation of miR-200c and miR-429 in CMCs. The ectopic expression of miR-200c in CMCs significantly downregulated Zeb1 and N-Cadherin expression. Our findings suggest that the significant downregulation of miR-200c/429 in CMCs maintains the expression of N-Cadherin, which may be important for its functional integrity.

Quantitative proteomics revealed the molecular characteristics of distinct types of granulated somatotroph adenomas

PURPOSE

Somatotroph adenomas are obviously heterogeneous in clinical characteristics, imaging performance, pathological diagnosis and therapeutic effect. The heterogeneity of the tumors, especially for SG and DG type adenomas, have attracted great interest in identifying the specific pathological markers and therapeutic targets of them. However, previous analyses of the molecular characteristics of the subtypes of somatotroph adenomas were performed at genomic and transcriptome level. The proteomic differences between the two subtypes of somatotroph adenomas are still unknown.

METHODS

Tumor samples were surgically removed from 10 sporadic pituitary somatotroph adenoma patients and grouped according to the pathological type. Tandem mass tag (TMT)-based quantitative proteomic analysis was employed to analyze the proteomic differences between SG and DG tumors.

RESULTS

In total, 228 differentially expressed proteins were identified between SG adenomas and DG adenomas. They were enriched mainly in extracellular matrix (ECM)-receptor interaction, leukocyte transendothelial migration, arrhythmogenic right ventricular cardiomyopathy and DNA replication pathways. Protein-protein interaction (PPI) network analysis indicated that Cadherin-1 and Catenin beta-1 were the most important key proteins in the differences between SG and DG adenomas. Immunohistochemistry (IHC) confirmed the expression levels of the key proteins.

CONCLUSIONS

This study provides large-scale proteome molecular characteristics of distinct granulation subtypes of somatotroph adenomas. Compared with DG adenomas, The differential protein of SG adenomas mostly enrich in invasive and proliferative functions and pathways at the proteomic level. Cadherin-1 and Catenin beta-1 play key roles in the different biological characteristics of the two tumor subtypes.

Collagens I and V differently regulate the proliferation and adhesion of rat islet INS-1 cells through the integrin β1/E-cadherin/β-catenin pathway

Extracellular matrix (ECM) plays an important role in tissue repair, cell proliferation, and differentiation. Our previous study showed that collagen I and collagen V differently regulate the proliferation of rat pancreatic β cells (INS-1 cells) through opposite influences on the nuclear translocation of β-catenin. In this study, we investigated the β-catenin pathway in INS-1 cells on dishes coated with collagen I or V. We found that nuclear translocation of the transcription factor Yes-associated protein (YAP) was enhanced by collagen I and suppressed by collagen V, but had no effect on INS-1 cell proliferation. Morphologically, INS-1 cells on collagen V-coated dishes showed stronger cell-to-cell adhesion, while the cells on collagen I-coated dishes showed weaker cell-to-cell adhesion in comparison with the cells on non-coated dishes. E-cadherin played an inhibitory role in the proliferation of INS-1 cells cultured on collagen I or collagen V coated dishes via regulation of the nuclear translocation of β-catenin. Integrin β1 was enhanced with collagen I, while it was repressed with collagen V. The integrin β1 pathway positively regulated the cell proliferation. Inhibition of integrin β1 pathway restored the protein level of E-cadherin and inhibited the nuclear translocation of β-catenin in the cells on collagen I-coated dishes, but no effect was observed in the cells on collagen V-coated dishes. In conclusion, collagen I enhances the proliferation of INS-1 cells via the integrin β1 and E-cadherin/β-catenin signaling pathway. In INS-1 cells on collagen V-coated dishes, both integrin β1 and E-cadherin/β-catenin signal pathways are involved in the inhibition of proliferation.

A complete Protocadherin-19 ectodomain model for evaluating epilepsy-causing mutations and potential protein interaction sites

Cadherin superfamily members play a critical role in differential adhesion during neurodevelopment, and their disruption has been linked to several neurodevelopmental disorders. Mutations in protocadherin-19 (PCDH19), a member of the δ-protocadherin subfamily of cadherins, cause a unique form of epilepsy called PCDH19 clustering epilepsy. While PCDH19 and other non-clustered δ-protocadherins form multimers with other members of the cadherin superfamily to alter adhesiveness, the specific protein surfaces responsible for these interactions are unknown. Only portions of the PCDH19 extracellular domain structure had been solved previously. Here, we present a structure of the missing segment from zebrafish Protocadherin-19 (Pcdh19) and create a complete ectodomain model. This model shows the structural environment for 97% of disease-causing missense mutations and reveals two potential surfaces for intermolecular interactions that could modify Pcdh19's adhesive strength and specificity.

Structural variability and dynamics in the ectodomain of an ancestral-type classical cadherin revealed by AFM imaging

Type III cadherin represents the ancestral form of classical cadherin in bilaterian metazoans. Drosophila possesses type III and type IVa cadherins, known as DN- and DE-cadherins, respectively. Mature DN- and DE-cadherins have 15 and 7 extracellular cadherin domain (EC) repeats, respectively, with DN-cadherin EC6–EC11 homologous to DE-cadherin EC1–EC6. These EC repeats contain predicted complete or partial Ca²⁺-free inter-EC linkers that potentially contribute to adhesion. Comparative structure–function studies of DN- and DE-cadherins may help us understand the ancestral and derived states of classical cadherin-mediated adhesion mechanisms. Here, using bead aggregation assays, we found that DN-cadherin EC1–EC11 and DE-cadherin EC1–EC6 exhibit Ca²⁺-dependent adhesive properties. Using high-speed atomic force microscopy (HS-AFM) imaging in solution, we show that both DN- and DE-cadherin ectodomains share a common morphological framework consisting of a strand-like and a globule-like portion. Furthermore, the DN-cadherin EC repeats are highly variable, flexible in morphology and have at least three bendable sites, one of which is located in EC6–EC11 and can act as a flexible hinge. Our findings provide insights into diversification of classical cadherin-mediated adhesion mechanisms.

This article has an associated First Person interview with the first author of the paper.

Summary: Atomic force microscopy imaging reveals that the ectodomain of an ancestral-type classical cadherin has a flexibly bendable strand-like portion responsible for homophilic adhesion.

A catenin of the plakophilin-subfamily, Pkp3, responds to canonical-Wnt pathway components and signals

Vertebrate beta-catenin plays a key role as a transducer of canonical-Wnt signals. We earlier reported that, similar to beta-catenin, the cytoplasmic signaling pool of p120-catenin-isoform1 is stabilized in response to canonical-Wnt signals. To obtain a yet broader view of the Wnt-pathway's impact upon catenin proteins, we focused upon plakophilin3 (plakophilin-3; Pkp3) as a representative of the plakophilin-catenin subfamily. Promoting tissue integrity, the plakophilins assist in linking desmosomal cadherins to intermediate filaments at desmosome junctions, and in common with other catenins they perform additional functions including in the nucleus. In this report, we test whether canonical-Wnt pathway components modulate Pkp3 protein levels. We find that in common with beta-catenin and p120-catenin-isoform1, Pkp3 is stabilized in the presence of a Wnt-ligand or a dominant-active form of the LRP6 receptor. Pkp3's levels are conversely lowered upon expressing destruction-complex components such as GSK3β and Axin, and in further likeness to beta-catenin and p120-isoform1, Pkp3 associates with GSK3beta and Axin. Finally, we note that Pkp3-catenin trans-localizes into the nucleus in response to Wnt-ligand and its exogenous expression stimulates an accepted Wnt reporter. These findings fit an expanded model where context-dependent Wnt-signals or pathway components modulate Pkp3-catenin levels. Future studies will be needed to assess potential gene regulatory, cell adhesive, or cytoskeletal effects.

The Chemistry and Biology of Ferroptosis

Ferroptosis is a recently described form of cell death driven by iron-dependent lipid peroxidation. This type of cell death was first observed in response to treatment of tumor cells with a small-molecule chemical probe named erastin. Most subsequent advances in understanding the mechanisms governing ferroptosis involved the use of genetic screens and small-molecule probes. We describe herein the utility and limitations of chemical probes that have been used to analyze and perturb ferroptosis, as well as mechanistic studies of ferroptosis that benefitted from the use of these probes and genetic screens. We also suggest probes for ferroptosis and highlight mechanistic questions surrounding this form of cell death that will be a high priority for exploration in the future.

Cadherins in early neural development

During early neural development, changes in signalling inform the expression of transcription factors that in turn instruct changes in cell identity. At the same time, switches in adhesion molecule expression result in cellular rearrangements that define the morphology of the emerging neural tube. It is becoming increasingly clear that these two processes influence each other; adhesion molecules do not simply operate downstream of or in parallel with changes in cell identity but rather actively feed into cell fate decisions. Why are differentiation and adhesion so tightly linked? It is now over 60 years since Conrad Waddington noted the remarkable "Constancy of the Wild Type" (Waddington in Nature 183: 1654-1655, 1959) yet we still do not fully understand the mechanisms that make development so reproducible. Conversely, we do not understand why directed differentiation of cells in a dish is sometimes unpredictable and difficult to control. It has long been suggested that cells make decisions as 'local cooperatives' rather than as individuals (Gurdon in Nature 336: 772-774, 1988; Lander in Cell 144: 955-969, 2011). Given that the cadherin family of adhesion molecules can simultaneously influence morphogenesis and signalling, it is tempting to speculate that they may help coordinate cell fate decisions between neighbouring cells in the embryo to ensure fidelity of patterning, and that the uncoupling of these processes in a culture dish might underlie some of the problems with controlling cell fate decisions ex-vivo. Here we review the expression and function of cadherins during early neural development and discuss how and why they might modulate signalling and differentiation as neural tissues are formed.

Ferroptosis: mechanisms, biology and role in disease

The research field of ferroptosis has seen exponential growth over the past few years, since the term was coined in 2012. This unique modality of cell death, driven by iron-dependent phospholipid peroxidation, is regulated by multiple cellular metabolic pathways, including redox homeostasis, iron handling, mitochondrial activity and metabolism of amino acids, lipids and sugars, in addition to various signalling pathways relevant to disease. Numerous organ injuries and degenerative pathologies are driven by ferroptosis. Intriguingly, therapy-resistant cancer cells, particularly those in the mesenchymal state and prone to metastasis, are exquisitely vulnerable to ferroptosis. As such, pharmacological modulation of ferroptosis, via both its induction and its inhibition, holds great potential for the treatment of drug-resistant cancers, ischaemic organ injuries and other degenerative diseases linked to extensive lipid peroxidation. In this Review, we provide a critical analysis of the current molecular mechanisms and regulatory networks of ferroptosis, the potential physiological functions of ferroptosis in tumour suppression and immune surveillance, and its pathological roles, together with a potential for therapeutic targeting. Importantly, as in all rapidly evolving research areas, challenges exist due to misconceptions and inappropriate experimental methods. This Review also aims to address these issues and to provide practical guidelines for enhancing reproducibility and reliability in studies of ferroptosis. Finally, we discuss important concepts and pressing questions that should be the focus of future ferroptosis research.

Differential Spatiotemporal Expression of Type I and Type II Cadherins Associated With the Segmentation of the Central Nervous System and Formation of Brain Nuclei in the Developing Mouse

Type I and type II classical cadherins comprise a family of cell adhesion molecules that regulate cell sorting and tissue separation by forming specific homo and heterophilic bonds. Factors that affect cadherin-mediated cell-cell adhesion include cadherin binding affinity and expression level. This study examines the expression pattern of type I cadherins (Cdh1, Cdh2, Cdh3, and Cdh4), type II cadherins (Cdh6, Cdh7, Cdh8, Cdh9, Cdh10, Cdh11, Cdh12, Cdh18, Cdh20, and Cdh24), and the atypical cadherin 13 (Cdh13) during distinct morphogenetic events in the developing mouse central nervous system from embryonic day 11.5 to postnatal day 56. Cadherin mRNA expression levels obtained from in situ hybridization experiments carried out at the Allen Institute for Brain Science (https://alleninstitute.org/) were retrieved from the Allen Developing Mouse Brain Atlas. Cdh2 is the most abundantly expressed type I cadherin throughout development, while Cdh1, Cdh3, and Cdh4 are expressed at low levels. Type II cadherins show a dynamic pattern of expression that varies between neuroanatomical structures and developmental ages. Atypical Cdh13 expression pattern correlates with Cdh2 in abundancy and localization. Analyses of cadherin-mediated relative adhesion estimated from their expression level and binding affinity show substantial differences in adhesive properties between regions of the neural tube associated with the segmentation along the anterior–posterior axis. Differences in relative adhesion were also observed between brain nuclei in the developing subpallium (basal ganglia), suggesting that differential cell adhesion contributes to the segregation of neuronal pools. In the adult cerebral cortex, type II cadherins Cdh6, Cdh8, Cdh10, and Cdh12 are abundant in intermediate layers, while Cdh11 shows a gradated expression from the deeper layer 6 to the superficial layer 1, and Cdh9, Cdh18, and Cdh24 are more abundant in the deeper layers. Person’s correlation analyses of cadherins mRNA expression patterns between areas and layers of the cerebral cortex and the nuclei of the subpallium show significant correlations between certain cortical areas and the basal ganglia. The study shows that differential cadherin expression and cadherin-mediated adhesion are associated with a wide range of morphogenetic events in the developing central nervous system including the organization of neurons into layers, the segregation of neurons into nuclei, and the formation of neuronal circuits.

Genome-wide signatures of mammalian skin covering evolution

Animal body coverings provide protection and allow for adaptation to environmental pressures such as heat, ultraviolet radiation, water loss, and mechanical forces. Here, using a comparative genomics analysis of 39 mammal species spanning three skin covering types (hairless, scaly and spiny), we found some genes (e.g., UVRAG, POLH, and XPC) involved in skin inflammation, skin innate immunity, and ultraviolet radiation damage repair were under selection in hairless ocean mammals (e.g., whales and manatees). These signatures might be associated with a high risk of skin diseases from pathogens and ultraviolet radiation. Moreover, the genomes from three spiny mammal species shared convergent genomic regions (EPHB2, EPHA4, and NIN) and unique positively selected genes (FZD6, INVS, and CDC42) involved in skin cell polarity, which might be related to the development of spines. In scaly mammals, the shared convergent genomic regions (e.g., FREM2) were associated with the integrity of the skin epithelium and epidermal adhesion. This study identifies potential convergent genomic features among distantly related mammals with the same skin covering type.