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Drosophila melanogaster has emerged as an ideal system for studying the networks that control tissue development and homeostasis and, given the similarity of the pathways involved, controlled and uncontrolled growth in mammalian systems. The signaling pathways used in patterning the Drosophila wing disc are well known and result in the emergence of interaction of these pathways with the Hippo signaling pathway, which plays a central role in controlling cell proliferation and apoptosis. Mechanical effects are another major factor in the control of growth, but far less is known about how they exert their control. Herein, we develop a mathematical model that integrates the mechanical interactions between cells, which occur via adherens and tight junctions, with the intracellular actin network and the Hippo pathway so as to better understand cell-autonomous and non-autonomous control of growth in response to mechanical forces.

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High glucose levels are associated with changes in macrophage polarisation and evidence indicates that the sustained or even short-term high glucose levels modulate inflammatory responses in macrophages. However, the mechanism by which macrophages can sense the changes in glucose levels are not clearly understood. We find that high glucose levels rapidly increase the α-E catenin protein level in RAW264.7 macrophages. We also find an attenuation of glucose-induced increase in α-E catenin when hexosamine biosynthesis (HB) pathway is inhibited either with glutamine depletion or with the drugs azaserine and tunicamycin. This indicates the involvement of HB pathway in this process. Then, we investigated the potential role of α-E catenin in glucose-induced macrophage polarisation. We find that the reduction in α-E catenin level using siRNA attenuates the glucose-induced changes of both IL-1ß and IL-12 mRNA levels under LPS-stimulated condition but does not affect TNF-α expression. Together this indicates that α-E catenin can sense the changes in glucose levels in macrophages via HB pathway and also can modulate the glucose-induced gene expression of inflammatory markers such as IL-1ß and IL-12. This identifies a new part of the mechanism by which macrophages are able to respond to changes in glucose levels.

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The recent finding that ß-catenin levels play an important rate-limiting role in processes regulating insulin secretion lead us to investigate whether its binding partner α-catenin also plays a role in this process. We find that levels of both α-E-catenin and α-N-catenin are rapidly up-regulated as levels of glucose are increased in rat clonal ß-cell models INS-1E and INS-832/3. Lowering in levels of either α-catenin isoform using siRNA resulted in significant increases in glucose stimulated insulin secretion (GSIS) and this effect was attenuated when ß-catenin levels were lowered indicating these proteins have opposing effects on insulin release. This effect of α-catenin knockdown on GSIS was not due to increases in insulin expression but was associated with increases in calcium influx into cells. Moreover, simultaneous depletion of α-E catenin and α-N catenin decreased the actin polymerisation to a similar degree as latrunculin treatment and inhibition of ARP 2/3 mediated actin branching with CK666 attenuated the α-catenin depletion effect on GSIS. This suggests α-catenin mediated actin remodelling may be involved in the regulation of insulin secretion. Together this indicates that α-catenin and ß-catenin can play opposing roles in regulating insulin secretion, with some degree of functional redundancy in roles of α-E-catenin and α-N-catenin. The finding that, at least in ß-cell models, the levels of each can be regulated in the longer term by glucose also provides a potential mechanism by which sustained changes in glucose levels might impact on the magnitude of GSIS.

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In healthy individuals, any rise in blood glucose levels is rapidly countered by the release of insulin from the ß-cells of the pancreas which in turn promotes the uptake and storage of the glucose in peripheral tissues. The ß-cells possess exquisite mechanisms regulating the secretion of insulin to ensure that the correct amount of insulin is released. These mechanisms involve tight control of the movement of insulin containing secretory vesicles within the ß-cells, initially preventing most vesicles being able to move to the plasma membrane. Elevated glucose levels trigger an influx of Ca2+ that allows fusion of the small number of insulin containing vesicles that are pre-docked at the plasma membrane but glucose also stimulates processes that allow other insulin containing vesicles located further in the cell to move to and fuse with the plasma membrane. The mechanisms controlling these processes are complex and not fully understood but it is clear that the interaction of the ß-cells with other ß-cells in the islets is very important for their ability to develop the appropriate machinery for proper regulation of insulin secretion. Emerging evidence indicates one factor that is key for this is the formation of homotypic cadherin mediated adherens junctions between ß-cells. Here, we review the evidence for this and discuss the mechanisms by which these adherens junctions might regulate insulin vesicle trafficking as well as the implications this has for understanding the dysregulation of insulin secretion seen in pathogenic states.

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Cadherin complexes mediate cell-cell adhesion and are crucial for embryonic development. Besides their structural function, cadherin complexes also transduce tension across the junction-actomyosin axis into proportional biochemical responses. Central to this mechanotransduction is the stretching of the cadherin-F-actin-linker α-catenin, which opens its central domain for binding to effectors such as vinculin. Mechanical unfolding of α-catenin leads to force-dependent reinforcement of cadherin-based junctions as studied in cell culture. The importance of cadherin mechanotransduction for embryonic development has not been studied yet. Here we used TALEN-mediated gene disruption to perturb endogenous αE-catenin in zebrafish development. Zygotic α-catenin mutants fail to maintain their epithelial barrier, resulting in tissue rupturing. We then specifically disrupted mechanotransduction, while maintaining cadherin adhesion, by expressing an αE-catenin construct in which the mechanosensitive domain was perturbed. Expression of either wild-type or mechano-defective α-catenin fully rescues barrier function in α-catenin mutants; however, expression of mechano-defective α-catenin also induces convergence and extension defects. Specifically, the polarization of cadherin-dependent, lamellipodia-driven cell migration of the lateral mesoderm was lost. These results indicate that cadherin mechanotransduction is crucial for proper zebrafish morphogenesis, and uncover one of the essential processes affected by its perturbation.

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α-Catenin is the primary link between the cadherin·catenin complex and the actin cytoskeleton. Mammalian αE-catenin is allosterically regulated: the monomer binds the ß-catenin·cadherin complex, whereas the homodimer does not bind ß-catenin but interacts with F-actin. As part of the cadherin·catenin complex, αE-catenin requires force to bind F-actin strongly. It is not known whether these properties are conserved across the mammalian α-catenin family. Here we show that αT (testes)-catenin, a protein unique to amniotes that is expressed predominantly in the heart, is a constitutive actin-binding α-catenin. We demonstrate that αT-catenin is primarily a monomer in solution and that αT-catenin monomer binds F-actin in cosedimentation assays as strongly as αE-catenin homodimer. The ß-catenin·αT-catenin heterocomplex also binds F-actin with high affinity unlike the ß-catenin·αE-catenin complex, indicating that αT-catenin can directly link the cadherin·catenin complex to the actin cytoskeleton. Finally, we show that a mutation in αT-catenin linked to arrhythmogenic right ventricular cardiomyopathy, V94D, promotes homodimerization, blocks ß-catenin binding, and in cardiomyocytes disrupts localization at cell-cell contacts. Together, our data demonstrate that αT-catenin is a constitutively active actin-binding protein that can physically couple the cadherin·catenin complex to F-actin in the absence of tension. We speculate that these properties are optimized to meet the demands of cardiomyocyte adhesion.

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The aim of this study was to provide insight into how curcumin reduces colon inflammation in the Mdr1a(-/-) mouse model of human inflammatory bowel disease using a combined transcriptomics and proteomics approach. Mdr1a(-/-) and FVB control mice were randomly assigned to an AIN-76A (control) diet or AIN-76A+0.2% curcumin. At 21 or 24weeks of age, colonic histological injury score (HIS) was determined, colon mRNA transcript levels were assessed using microarrays and colon protein expression was measured using 2D gel electrophoresis and LCMS protein identification. Colonic HIS of Mdr1a(-/-) mice fed the AIN-76A diet was higher (P<.001) than FVB mice fed the same diet; the curcumin-supplemented diet reduced colonic HIS (P<.05) in Mdr1a(-/-) mice. Microarray and proteomics analyses combined with new data analysis tools, such as the Ingenuity Pathways Analysis regulator effects analysis, showed that curcumin's antiinflammatory activity in Mdr1a(-/-) mouse colon may be mediated by activation of α-catenin, which has not previously been reported. We also show evidence to support curcumin's action via multiple molecular pathways including reduced immune response, increased xenobiotic metabolism, resolution of inflammation through decreased neutrophil migration and increased barrier remodeling. Key transcription factors and other regulatory molecules (ERK, FN1, TNFSF12 and PI3K complex) activated in inflammation were down-regulated by dietary intervention with curcumin.

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Objective To detect the expressions of Numb and α-catenin in the gastric cancer and matched normal gastric mucosa,and to analyze their relationship with clinicopathological factors of gastric cancer and explore their roles in gastric carcinogenesis and progression.Methods Immunohistochemical method was used to detect the expressions of Numb and α-catenin in 109 cases of tumor specimens and 97 cases of matched normal gastric mucosa.The correlations between Numb,α-catenin and clinicopathological factors were analyzed.Results The positive rates of Numb and α-catenin in gastric cancer were significantly lower than those in normal gastric mucosa (60.6％ ∶ 100.0％,x2 =48.361,P =0.000;76.1％ ∶ 100.0％,x2 =26.480,P=0.000).The expression of Numb protein was correlated with Lauren type (x2 =17.018,P =0.000) and tubular adenocarcinoma differentiation (x2 =17.586,P =0.000).The expression of α-catenin protein was correlated with Borrmann type (x2 =6.700,P =0.035),Lauren type (x2 =11.098,P =0.001),tubular adenocarcinoma differentiation (x2 =8.203,P =0.017) and lymph node metastasis (x2 =6.402,P =0.011).The expressions of Numb and α-catenin were statistically correlated in 109 cases of gastric cancer (rk =0.184,P =0.028).Conclusion Compared with normal gastric mucosa,both Numb and α-catenin expressions are down-regulated and the two expressions are correlated in gastric cancer.Numb and α-catenin may be involved in the regulation of histological differentiation of gastric cancer by certain passages,Numb protein may be adjusted by α-catenin pathway which is involved in Wnt-β-catenin pathway,and thus plays an important role in promoting cell proliferation,invasion and metastasis in human gastric cancer.

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Signaling via the Rho GTPases provides crucial regulation of numerous cell polarization events, including apicobasal (AB) polarity, polarized cell migration, polarized cell division and neuronal polarity. Here we review the relationships between the Rho family GTPases and epithelial AB polarization events, focusing on the 3 best-characterized members: Rho, Rac and Cdc42. We discuss a multitude of processes that are important for AB polarization, including lumen formation, apical membrane specification, cell-cell junction assembly and maintenance, as well as tissue polarity. Our discussions aim to highlight the immensely complex regulatory mechanisms that encompass Rho GTPase signaling during AB polarization. More specifically, in this review we discuss several emerging common themes, that include: 1) the need for Rho GTPase activities to be carefully balanced in both a spatial and temporal manner through a multitude of mechanisms; 2) the existence of signaling feedback loops and crosstalk to create robust cellular responses; and 3) the frequent multifunctionality that exists among AB polarity regulators. Regarding this latter theme, we provide further discussion of the potential plasticity of the cell polarity machinery and as a result the possible implications for human disease.

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Poly-ADP-ribose (PAR) is a polymer of up to 400 ADP-ribose units synthesized by poly-ADP-ribose-polymerases (PARPs) and degraded by poly-ADP-ribose-glycohydrolase (PARG). Nuclear PAR modulates chromatin compaction, affecting nuclear functions (gene expression, DNA repair). Diverse defined PARP cytoplasmic allocation patterns contrast with the yet still imprecise PAR distribution and still unclear functions. Based on previous evidence from other models, we hypothesized that PAR could be present in epithelial cells where cadherin-based adherens junctions are linked with the actin cytoskeleton (constituting the adhesion belt). In the present work, we have examined through immunofluorescence and confocal microscopy, the subcellular localization of PAR in an epithelial monkey kidney cell line (VERO). PAR was distinguished colocalizing with actin and vinculin in the epithelial belt, a location that has not been previously reported. Actin filaments disruption with cytochalasin D was paralleled by PAR belt disruption. Conversely, PARP inhibitors 3-aminobenzamide, PJ34 or XAV 939, affected PAR belt synthesis, actin distribution, cell shape and adhesion. Extracellular calcium chelation displayed similar effects. Our results demonstrate the existence of PAR in a novel subcellular localization. An initial interpretation of all the available evidence points towards TNKS-1 as the most probable PAR belt architect, although TNKS-2 involvement cannot be discarded. Forthcoming research will test this hypothesis as well as explore the existence of the PAR belt in other epithelial cells and deepen into its functional implications.

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α-Catenin (α-cat) is an actin-binding protein required for cell-cell cohesion. Although this adhesive function for α-cat is well appreciated, cells contain a substantial amount of nonjunctional α-cat that may be used for other functions. We show that α-cat is a nuclear protein that can interact with ß-catenin (ß-cat) and T-cell factor (TCF) and that the nuclear accumulation of α-cat depends on ß-cat. Using overexpression, knockdown, and chromatin immunoprecipitation approaches, we show that α-cat attenuates Wnt/ß-cat-responsive genes in a manner that is downstream of ß-cat/TCF loading on promoters. Both ß-cat- and actin-binding domains of α-cat are required to inhibit Wnt signaling. A nuclear-targeted form of α-cat induces the formation of nuclear filamentous actin, whereas cells lacking α-cat show altered nuclear actin properties. Formation of nuclear actin filaments correlates with reduced RNA synthesis and altered chromatin organization. Conversely, nuclear extracts made from cells lacking α-cat show enhanced general transcription in vitro, an activity that can be partially rescued by restoring the C-terminal actin-binding region of α-cat. These data demonstrate that α-cat may limit gene expression by affecting nuclear actin organization.

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INTRODUCTION: Cell adhesion molecules (CAM) are required for maintaining a normal epithelial phenotype, and abnormalities in CAM expression have been related to cancer progression, including bladder urothelial carcinomas. There is only one study that correlates E-cadherin and α-, β- and γ-catenin expression with prognosis of upper tract urothelial carcinomas. Our aim is to study the pattern of immune expression of these CAMs in urothelial carcinomas from the renal pelvis and ureter in patients who have been treated surgically. Our goal is to correlate these expression levels and characteristics with well-known prognostic parameters for disease-free survival. MATERIALS AND METHODS: We evaluated specimens from 20 patients with urothelial carcinomas of the renal pelvis and ureter who were treated with nephroureterectomy or ureterectomy between June 1997 and January 2007. CAM expression was evaluated by immunohistochemistry in a tissue microarray and correlated with histopathological characteristics and patient outcomes after a mean follow-up of 55 months. RESULTS: We observed a relationship between E-cadherin expression and disease recurrence. Disease recurrence occurred in 87.5% of patients with strong E-cadherin expression. Only 50.0% of patients with moderate expression and 0% of patients with weak or no expression of E-cadherin had disease recurrence (p = 0.014). There was also a difference in disease-free survival. Patients with strong E-cadherin expression had a mean disease-free survival rate of 49.1 months, compared to 83.9 months for patients with moderate expression (p = 0.011). Additionally, an absence of α-catenin expression was associated with tumors that were larger than 3 cm (p = 0.003). CONCLUSIONS: We demonstrated for the first time that immune expression of E-cadherin is related to tumor recurrence and disease-free survival rates, and the absence of α-catenin expression is related to tumor size in upper tract urothelial carcinomas.

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PURPOSE: Among the cell adhesion molecules, alpha-catenin and E-cadherin play an important part in maintaining normal cell structure. The change in expression of cell adhesion molecules affects the invasion and metastasis of a tumor and the prognosis for patients. In this study, we evaluated the relationship between the expression of cell adhesion molecules and the histopathologic characteristics of stage III colon cancer. METHODS: The relationship between the immunohistochemical expression of cell adhesion molecules and tumor progression were statistically analyzed in 40 patients with stage III colon cancer. RESULTS: There were no statistically significant correlations between loss of membranous alpha-catenin and E-cadherin expressions and such variables as histologic differentiation and lymph node disease based on the criteria of the American Joint Committee on Cancer (AJCC). A significant correlation, however, existed between depth of mural invasion and loss of expressions of both alpha-catenin and E-cadherin (P=0.001 and P=0.002, respectively). Expressions of both alpha-catenin and E-cadherin were also significantly decreased in patients showing liver metastases during follow-up (P=0.019 and P=0.015, respectively). CONCLUSION: Immunohistochemical analyses of alpha-catenin and E-cadherin expressions may be available as predictors for distant metastasis, especially in stage III colon cancer. Such analyses may also help to identify appropriate therapeutic strategies and the need for intensive follow-up in patients with stage III colon cancer.

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Objective To elucidate the expression pattern of E-cadherin/catenin adhesion complex and its association with pathologic features in nasopharyngeal carcinoma(NPC).Methods Fifty-two non-keratinizing NPC specimens with adjacent non-neoplastic mucosa were examined for E-cadherin,?-CATenin,?-CATenin.Results Abnormal expression rate of E-cadherin,?-catenin and ?-catenin in NPCs were 48.1%(25/52),32.7%(17/52) and 34.6%(18/52),respectively,whereas all adjacent non-neoplastic tissues normally expressed these proteins.Difference of expression of E-cadherin,?-catenin and ?-catenin between tumor tissues and non-cancerous tissues was statistically significant(P

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OBJECTIVE: To evaluate the correlation of the expression of E-cadherin, alpha-catenin, beta-catenin and the clinicopathological features in endometrial cancer (EC) and atypical complex endometrial hyperplasia (ACEH). METHODS: Immunohistochemical (IHC) staining of E-cadherin, alpha-catenin, beta-catenin was performed in tissues of 6 ACEHs, 44 endometrioid ECs. We analyzed the correlation of the expression of IHC staining with the prognostic factors according to tumor stage of ACEH and EC, histopathologic grade, and myometrial invasion. RESULTS: According to tumor stage, reduced E-cadherin expression and abnormal alpha-catenin expression were observed more frequently in advanced stage (reduced E-cadherin: ACEH 0%, stage I-II 47.2%, stage III-IV 62.5%, p=0.050; abnormal alpha-catenin: ACEH 0%, stage I-II 27.8%, stage III-IV 62.5%, p=0.035). All of the IHC staining showed no correlation with the depth of myometrial invasion but showed correlation with presence of myometrial invasion (reduced E-cadherin: invasion(-) 14.3%, invasion(+) 66.7%, p =0.001; abnormal alpha-catenin: invasion(-) 7.1%, invasion (+) 46.0%, p=0.010; abnormal beta-catenin: invasion(-) 7.1%, invasion(+) 63.0%, p=0.000). According to histological differentiation only abnormal beta-catenin expression shows relationship with histopathologic grade (grade 1:23.1%, grade 2:60%, grade 3:62.5%, p=0.039). CONCLUSION: Expression of E-cadherin and alpha-catenin showed significantly more reduced expression in EC than in ACEH, and more reduced expression in advanced stage, myometrial invasion and high histopathologic grade. And alpha-catenin showed more frequent abnormal expression in advanced stage, myometrial invasion and beta-catenin showed more frequent in myometrial invasion, high histopathologic grade significantly. These results suggests that the expression of E-cadherin and alpha-catenin, beta-catenin in EC and ACEH could be related to prognosis of the tumor.

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PURPOSE: E-cadherin plays a crucial role in cell-cell adhesion in epithelial tissues. The function of E-cadherin is thought to be regulated by its associated cytoplasmic proteins including alpha-catenin. Recent studies have shown a correlation between decreased E-cadherin and alpha-catenin expression and tumor invasion and metastasis. METHODS: We conducted an immunohistochemical staining of epithelial (E)-cadherin and alpha-catenin expression in 129 tissue samples taken from colorectal cancer patients undergoing surgical treatment by the avidin-biotin-peroxidase complex method. We classified tumors into three types according to the expression modality. Cancer cells with strong expression at the cell-cell boundaries were defined as two positive (++);, when the expression was positive, but not concentrated at the cell-cell boundaries and weak, they were defined as one positive (+);, and when the tumor showed no staining, they were defined as negative (-). The relationships between these three expression types and the clinicopathological features of colorectal cancer were investigated. RESULTS: The expression type of E-cadherin and alpha-catenin was two positive (++) in 5 and 20 of the cancer tissue specimens, one positive (+) in 66 and 56, and negative (-) in 58 (45%) and 53 (41.1%). Negative expression of E-cadherin and alpha-catenin were significantly correlated with tumor differentiation, Dukes'stage, and lymph node metastasis of the colorectal cancer patients (P<0.05). CONCLUSION: The expression type of E-cadherin is signifi-cantly corretated to that of alpha-catenin, and the loss of their expression indicates the invasion and metastasis of colorectal cancer. To predict tumor invasion and metastasis in colorectal carcinoma, it is useful to investigate both the expression of E-cadherin and of alpha-catenin.

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The E-cadherin, alpha-catenin, and beta-catenin expressions were immunohistochemically investigated in paraffin-embedded materials of 80 cases of colorectal adenocarcinomas. The staining similar to normal colorectal mucosa with preserved strong membranous staining pattern was considered normal or preserved expression. The X2 test was used to analyse the statistical correlation of cadherin/catenin expression with clinicopathologic parameters and the Breslow test for the correlation with survival length. Normal colorectal mucosa showed strong membranous expression of cadherin/catenin complex. The reduced E-cadherin, alpha-catenin, and beta-catenin expression were found in 53/80 (66.3%), 46/80 (57.5%), and 44/80 (55.5%) cases of colorectal cancers examined, respectively. There were significant correlations between E- cadherin and alpha -catenin (p=0.035), and between alpha-catenin and beta-catenin (p=0.013). The reduced E-cadherin expression was associated with histologic dedifferentiation, tumor depth, lymph node metastasis, clinical stage (p<0.05), poor clinical outcome in stage II (p=0.016) and the reduced alpha-catenin expression with lymph node metastasis and clinical stage (p<0.05). Reduced expression of two or more proteins was correlated with lymph node matastasis, histologic dedifferentiation, clinical stage, and survival (p<0.05). The present study demonstrates a significant down-regulation of E-cadherin and alpha-catenin expression in colorectal cancer is associated with tumor invasiveness, histologic dedifferentiation, lymph node metastasis, and clinical stage. These results suggest that E-cadherin and alpha-catenin may be useful markers of invasiveness, lymph node metastatic potential, and clinical stage and of value as prognostic markers in the earlier stage. Further studies are needed to confirm the prognostic value of these cadherin/catenin complex.

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