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Alpha Catenin
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Masayuki Ozawa – One of the best experts on this subject based on the ideXlab platform.
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Identification of regions of α-Catenin required for desmosome organization in epithelial cells
International journal of molecular medicine, 2005Co-Authors: Tamotsu Taniguchi, Mutsumi Miyazaki, Yayoi Miyashita, Terukatsu Arima, Masayuki OzawaAbstract:Alpha–Catenin, a cadherin-associated protein, links cadherin/beta-Catenin and cadherin/plakoglobin complexes to the actin cytoskeleton. This protein is required for the function of cadherins, cell adhesion molecules. We transfected an Alpha–Catenin-deficient colon carcinoma line, which cannot organize desmosomes, with a series of Alpha–Catenin mutant constructs. We examined the formation of desmosomes in these cells by immunofluorescence staining using anti-desmoglein and anti-desmoplakin antibodies. The results demonstrated that either the middle or the carboxy-terminal region of Alpha–Catenin was required for desmosome formation. Immunoblot analysis revealed that the amounts of desmoglein and desmoplakin did not differ significantly between cells that were capable of forming desmosomes and those that failed to form desmosomes. Cell surface biotinylation revealed that desmoglein was retained intracellularly in cells that could not organize desmosomes. The internal domain binds vinculin and Alpha-actinin, actin-binding proteins, while the carboxy-terminal domain has the ability to bind and bundle actin filaments. These results indicate that the interaction of Alpha–Catenin and actin functions in the assembly of desmosomes in epithelial cells.
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The reduced expression of e-cadherin, Alpha–Catenin and gamma-Catenin but not beta-Catenin in human lung cancer.
Oncology Reports, 1999Co-Authors: Hironobu Toyoyama, Kensuke Nuruki, Hiroki Ogawa, Masayuki Yanagi, Hidehiko Matsumoto, Hiroo Nishijima, Tetsurou Shimotakahara, Takashi Aikou, Masayuki OzawaAbstract:: Cadherins are Ca2+-dependent cell-cell adhesion molecules, and are involved in the formation and maintenance of the histo-architecture. Using a combination of biochemical and immunohistochemical methods, we analyzed the expression of cadherin-Catenin complexes in 37 non-small cell lung carcinomas. In 19 cases, decreased expression of E-cadherin protein was observed. In 12 of them, decreased expression of Alpha–Catenin protein was also observed. Thus, decreased expression of Alpha–Catenin was apparently preceded by decreased expression of E-cadherin. In no cases was decreased expression of beta-Catenin observed. In the 12 cases in which mRNA expression was analyzed by Northern blot analysis, decreased expression of mRNAs for E-cadherin and Alpha–Catenin was observed in 11 and 9 cases, respectively. In cases with reduced E-cadherin and Alpha–Catenin expression, immunohistochemistry revealed two types of staining pattern for the proteins. In the first type, almost all the cells in a tumor were stained weakly (homogeneous pattern). In the second type, different percentages of cells were stained strongly, the rest being almost negative for the staining (heterogeneous pattern).
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Altered cell adhesion activity by pervanadate due to the dissociation of Alpha–Catenin from the E-cadherin.Catenin complex.
The Journal of biological chemistry, 1998Co-Authors: Masayuki Ozawa, Rolf KemlerAbstract:Leukemia cells (K562) that grow as non-adhesive single cells and have no endogenous cadherin were transfected with an E-cadherin expression vector, and cell clones stably expressing E-cadherin on their surface were established. The expression of E-cadherin induced the up-regulation of Catenins, and E-cadherin became associated with Catenins. The transfected cells grew as floating aggregates. Cell aggregation was Ca2+-dependent and was inhibited by E-cadherin antibodies. The aggregates dissociated into single cells on the addition of pervanadate. Pervanadate caused a dramatic augmentation of the phosphorylation of E-cadherin, beta-Catenin, and gamma-Catenin (plakoglobin), but Alpha–Catenin was not detectably phosphorylated. After pervanadate treatment, beta-Catenin and gamma-Catenin migrated more slowly on gel electrophoresis, suggesting changes in their conformations due to eventual changes in their phosphorylation levels. In the treated cells, a significant amount of Alpha–Catenin was dissociated from the E-cadherin.Catenin complex. Aggregates of cells expressing an E-cadherin chimeric molecule covalently linked with Alpha–Catenin were not dissociated on pervanadate treatment, supporting the idea that the dissociation of Alpha–Catenin from the complex underlies the observed E-cadherin dysfunction.
Akira Nagafuchi – One of the best experts on this subject based on the ideXlab platform.
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α-Catenin-independent Recruitment of ZO-1 to Nectin-based Cell-Cell Adhesion Sites through Afadin
Molecular biology of the cell, 2001Co-Authors: Shigekazu Yokoyama, Morito Monden, Akira Nagafuchi, Kouichi Tachibana, Hiroyuki Nakanishi, Yasunori Yamamoto, Kenji Irie, Kenji Mandai, Yoshimi TakaiAbstract:ZO-1 is an actin filament (F-actin)-binding protein that localizes to tight junctions and connects claudin to the actin cytoskeleton in epithelial cells. In nonepithelial cells that have no tight junctions, ZO-1 localizes to adherens junctions (AJs) and may connect cadherin to the actin cytoskeleton indirectly through beta- and Alpha–Catenins as one of many F-actin-binding proteins. Nectin is an immunoglobulin-like adhesion molecule that localizes to AJs and is associated with the actin cytoskeleton through afadin, an F-actin-binding protein. Ponsin is an afadin- and vinculin-binding protein that also localizes to AJs. The nectin-afadin complex has a potency to recruit the E-cadherin-beta-Catenin complex through Alpha–Catenin in a manner independent of ponsin. By the use of cadherin-deficient L cell lines stably expressing various components of the cadherin-Catenin and nectin-afadin systems, and Alpha–Catenin-deficient F9 cell lines, we examined here whether nectin recruits ZO-1 to nectin-based cell-cell adhesion sites. Nectin showed a potency to recruit not only Alpha–Catenin but also ZO-1 to nectin-based cell-cell adhesion sites. This recruitment of ZO-1 was dependent on afadin but independent of Alpha–Catenin and ponsin. These results indicate that ZO-1 localizes to cadherin-based AJs through interactions not only with Alpha–Catenin but also with the nectin-afadin system.
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Co-expression of E-cadherin and α-Catenin molecules in colorectal cancer
Surgery today, 1999Co-Authors: Tatsushi Kitagawa, Shoichiro Tsukita, Akira Nagafuchi, Koichi Matsumoto, Hiroshi SuzukiAbstract:Immunohistochemical staining for epithelial (E)-cadherin and Alpha–Catenin was performed using frozen sections taken from fresh operative specimens, by the avidin-biotin-peroxidase complex method. Tumors were classified into three types according to the expression modality. Cancer cells with expression at the cell-cell boundaries were defined as normal; when the expression was positive, but not concentrated at the cell-cell boundaries, they were defined as cytoplasmic; and when the tumor showed no staining, they were defined as lost. The relationship between these three expression types and the clinicopathological features of colorectal cancer was investigated. In all 50 normal mucosa samples, E-cadherin and Alpha–Catenin were coexpressed normally. The expression type of E-cadherin and Alpha–Catenin was normal in 11 and 13 of the cancer tissue specimens, respectively, cytoplasmic in 26 and 29, respectively, and lost in 13 and 8, respectively. Cytoplasmic or lost expression was observed in cancer demonstrating an advanced clinical stage (E-cadherin, P = 0.0065; Alpha–Catenin, P = 0.0069), advanced tumor penetration (P = 0.0003, P = 0.0001), undifferentiated tumor histology (P = 0.0196, P = 0.0343), widespread lymph node involvement (P = 0.0204, P = 0.0340), and liver metastasis (P = 0.0063, P = 0.0299). In conclusion, the expression type of E-cadherin is significantly correlated to that of Alpha–Catenin, and the loss of their expression indicates the metastatic potentiality of colorectal cancer.
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dynamics of connexins e cadherin and Alpha Catenin on cell membranes during gap junction formation
Journal of Cell Science, 1997Co-Authors: Kazushi Fujimoto, Shoichiro Tsukita, Akira Nagafuchi, Akio Kuraoka, Akiko Ohokuma, Yosaburo ShibataAbstract:We examined the dynamics of connexins, E-cadherin and Alpha–Catenin during gap-junction disassembly and assembly in regeneration hepatocytes by immunofluorescence microscopy, and immunogold-electron microscopy using SDS-digested freeze-replicas. The present findings suggest that during the disappearance of gap junctions most of the gap junction plaques are broken up into smaller aggregates, and then the gap junction proteins may be removed from the cell membrane, but some of the connexons or connexins remain dispersed in the plane of membrane as pure morphologically indistinguishable intramembrane proteins. Double-immunogold electron microscopy using a polyclonal antibody for connexins and a monoclonal antibody for E-cadherin or Alpha–Catenin revealed co-localization of these molecules at cell-to-cell contact sites during the reappearance of gap junction plaques. This implies that, at least in regenerating hepatocytes, the cadherin-Catenin complex-mediated cell-to-cell contact sites act as foci for gap junction formation. In addition, connexin-immunoreactivity was also observed along tight junctional strands, suggesting that the gap junction may also form along the tight junctions.
Shoichiro Tsukita – One of the best experts on this subject based on the ideXlab platform.
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Co-expression of E-cadherin and α-Catenin molecules in colorectal cancer
Surgery today, 1999Co-Authors: Tatsushi Kitagawa, Shoichiro Tsukita, Akira Nagafuchi, Koichi Matsumoto, Hiroshi SuzukiAbstract:Immunohistochemical staining for epithelial (E)-cadherin and Alpha–Catenin was performed using frozen sections taken from fresh operative specimens, by the avidin-biotin-peroxidase complex method. Tumors were classified into three types according to the expression modality. Cancer cells with expression at the cell-cell boundaries were defined as normal; when the expression was positive, but not concentrated at the cell-cell boundaries, they were defined as cytoplasmic; and when the tumor showed no staining, they were defined as lost. The relationship between these three expression types and the clinicopathological features of colorectal cancer was investigated. In all 50 normal mucosa samples, E-cadherin and Alpha–Catenin were coexpressed normally. The expression type of E-cadherin and Alpha–Catenin was normal in 11 and 13 of the cancer tissue specimens, respectively, cytoplasmic in 26 and 29, respectively, and lost in 13 and 8, respectively. Cytoplasmic or lost expression was observed in cancer demonstrating an advanced clinical stage (E-cadherin, P = 0.0065; Alpha–Catenin, P = 0.0069), advanced tumor penetration (P = 0.0003, P = 0.0001), undifferentiated tumor histology (P = 0.0196, P = 0.0343), widespread lymph node involvement (P = 0.0204, P = 0.0340), and liver metastasis (P = 0.0063, P = 0.0299). In conclusion, the expression type of E-cadherin is significantly correlated to that of Alpha–Catenin, and the loss of their expression indicates the metastatic potentiality of colorectal cancer.
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Expression of E-Cadherin and α-Catenin in Patients with Colorectal Carcinoma: Correlation with Cancer Invasion and Metastasis
American journal of clinical pathology, 1999Co-Authors: Junji Gofuku, Hitoshi Shiozaki, Shigeo Matsui, Shoichiro Tsukita, Shigeyuki Tamura, Masatoshi Inoue, Yuichiro Doki, Toshimasa Tsujinaka, Nobuteru Kikkawa, Morito MondenAbstract:Cadherins form complexes with groups of cytoplasmic proteins, such as Alpha-, beta-, and gamma-Catenins, that link the cadherin molecule to the cytoskeleton. In this study, we conducted an immunohistochemical investigation of E-cadherin and Alpha–Catenin expression in 100 tissue samples obtained from colorectal cancer patients undergoing surgical treatment. Reduced expression of Alpha–Catenin was observed in 56 (56%) of the cases and found to be significantly correlated with the depth of invasion of the patients’ colorectal cancer and its metastasis to lymph nodes and liver. In contrast, E-cadherin expression was reduced in 29 (29%) of the cases and was not significantly correlated with either depth of invasion or metastasis. Although the levels of expression of these proteins were positively correlated, coexpression pattern analysis showed that invasion and metastasis were correlated with a reduction of Alpha–Catenin expression regardless of the status of E-cadherin staining. Thus, to predict tumor invasion and metastasis in colorectal adenocarcinoma, it is useful to investigate not just the expression of E-cadherin but also the expression of Alpha–Catenin.
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dynamics of connexins e cadherin and Alpha Catenin on cell membranes during gap junction formation
Journal of Cell Science, 1997Co-Authors: Kazushi Fujimoto, Shoichiro Tsukita, Akira Nagafuchi, Akio Kuraoka, Akiko Ohokuma, Yosaburo ShibataAbstract:We examined the dynamics of connexins, E-cadherin and Alpha–Catenin during gap-junction disassembly and assembly in regeneration hepatocytes by immunofluorescence microscopy, and immunogold-electron microscopy using SDS-digested freeze-replicas. The present findings suggest that during the disappearance of gap junctions most of the gap junction plaques are broken up into smaller aggregates, and then the gap junction proteins may be removed from the cell membrane, but some of the connexons or connexins remain dispersed in the plane of membrane as pure morphologically indistinguishable intramembrane proteins. Double-immunogold electron microscopy using a polyclonal antibody for connexins and a monoclonal antibody for E-cadherin or Alpha–Catenin revealed co-localization of these molecules at cell-to-cell contact sites during the reappearance of gap junction plaques. This implies that, at least in regenerating hepatocytes, the cadherin-Catenin complex-mediated cell-to-cell contact sites act as foci for gap junction formation. In addition, connexin-immunoreactivity was also observed along tight junctional strands, suggesting that the gap junction may also form along the tight junctions.