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Masayuki Ozawa – One of the best experts on this subject based on the ideXlab platform.

  • Identification of regions of α-Catenin required for desmosome organization in epithelial cells
    International journal of molecular medicine, 2005
    Co-Authors: Tamotsu Taniguchi, Mutsumi Miyazaki, Yayoi Miyashita, Terukatsu Arima, Masayuki Ozawa

    Abstract:

    AlphaCatenin, 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 AlphaCatenin-deficient colon carcinoma line, which cannot organize desmosomes, with a series of AlphaCatenin 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 AlphaCatenin 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 AlphaCatenin and actin functions in the assembly of desmosomes in epithelial cells.

  • The reduced expression of e-cadherin, AlphaCatenin and gamma-Catenin but not beta-Catenin in human lung cancer.
    Oncology Reports, 1999
    Co-Authors: Hironobu Toyoyama, Kensuke Nuruki, Hiroki Ogawa, Masayuki Yanagi, Hidehiko Matsumoto, Hiroo Nishijima, Tetsurou Shimotakahara, Takashi Aikou, Masayuki Ozawa

    Abstract:

    : 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 AlphaCatenin protein was also observed. Thus, decreased expression of AlphaCatenin 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 AlphaCatenin was observed in 11 and 9 cases, respectively. In cases with reduced E-cadherin and AlphaCatenin 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).

  • Altered cell adhesion activity by pervanadate due to the dissociation of AlphaCatenin from the E-cadherin.Catenin complex.
    The Journal of biological chemistry, 1998
    Co-Authors: Masayuki Ozawa, Rolf Kemler

    Abstract:

    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 AlphaCatenin 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 AlphaCatenin was dissociated from the E-cadherin.Catenin complex. Aggregates of cells expressing an E-cadherin chimeric molecule covalently linked with AlphaCatenin were not dissociated on pervanadate treatment, supporting the idea that the dissociation of AlphaCatenin from the complex underlies the observed E-cadherin dysfunction.

Akira Nagafuchi – One of the best experts on this subject based on the ideXlab platform.

  • α-Catenin-independent Recruitment of ZO-1 to Nectin-based Cell-Cell Adhesion Sites through Afadin
    Molecular biology of the cell, 2001
    Co-Authors: Shigekazu Yokoyama, Morito Monden, Akira Nagafuchi, Kouichi Tachibana, Hiroyuki Nakanishi, Yasunori Yamamoto, Kenji Irie, Kenji Mandai, Yoshimi Takai

    Abstract:

    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 AlphaCatenins 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 AlphaCatenin 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 AlphaCatenin-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 AlphaCatenin but also ZO-1 to nectin-based cell-cell adhesion sites. This recruitment of ZO-1 was dependent on afadin but independent of AlphaCatenin and ponsin. These results indicate that ZO-1 localizes to cadherin-based AJs through interactions not only with AlphaCatenin but also with the nectin-afadin system.

  • Co-expression of E-cadherin and α-Catenin molecules in colorectal cancer
    Surgery today, 1999
    Co-Authors: Tatsushi Kitagawa, Shoichiro Tsukita, Akira Nagafuchi, Koichi Matsumoto, Hiroshi Suzuki

    Abstract:

    Immunohistochemical staining for epithelial (E)-cadherin and AlphaCatenin 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 AlphaCatenin were coexpressed normally. The expression type of E-cadherin and AlphaCatenin 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; AlphaCatenin, 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 AlphaCatenin, and the loss of their expression indicates the metastatic potentiality of colorectal cancer.

  • dynamics of connexins e cadherin and Alpha Catenin on cell membranes during gap junction formation
    Journal of Cell Science, 1997
    Co-Authors: Kazushi Fujimoto, Shoichiro Tsukita, Akira Nagafuchi, Akio Kuraoka, Akiko Ohokuma, Yosaburo Shibata

    Abstract:

    We examined the dynamics of connexins, E-cadherin and AlphaCatenin 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 AlphaCatenin 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.

  • Co-expression of E-cadherin and α-Catenin molecules in colorectal cancer
    Surgery today, 1999
    Co-Authors: Tatsushi Kitagawa, Shoichiro Tsukita, Akira Nagafuchi, Koichi Matsumoto, Hiroshi Suzuki

    Abstract:

    Immunohistochemical staining for epithelial (E)-cadherin and AlphaCatenin 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 AlphaCatenin were coexpressed normally. The expression type of E-cadherin and AlphaCatenin 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; AlphaCatenin, 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 AlphaCatenin, and the loss of their expression indicates the metastatic potentiality of colorectal cancer.

  • Expression of E-Cadherin and α-Catenin in Patients with Colorectal Carcinoma: Correlation with Cancer Invasion and Metastasis
    American journal of clinical pathology, 1999
    Co-Authors: Junji Gofuku, Hitoshi Shiozaki, Shigeo Matsui, Shoichiro Tsukita, Shigeyuki Tamura, Masatoshi Inoue, Yuichiro Doki, Toshimasa Tsujinaka, Nobuteru Kikkawa, Morito Monden

    Abstract:

    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 AlphaCatenin expression in 100 tissue samples obtained from colorectal cancer patients undergoing surgical treatment. Reduced expression of AlphaCatenin 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 AlphaCatenin 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 AlphaCatenin.

  • dynamics of connexins e cadherin and Alpha Catenin on cell membranes during gap junction formation
    Journal of Cell Science, 1997
    Co-Authors: Kazushi Fujimoto, Shoichiro Tsukita, Akira Nagafuchi, Akio Kuraoka, Akiko Ohokuma, Yosaburo Shibata

    Abstract:

    We examined the dynamics of connexins, E-cadherin and AlphaCatenin 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 AlphaCatenin 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.