Osaka University

About: Osaka University is a education organization based out in Osaka, Japan. It is known for research contribution in the topics: Laser & Catalysis. The organization has 83778 authors who have published 185669 publications receiving 5158122 citations. The organization is also known as: Ōsaka daigaku.

Regulation of Cell–Cell Adhesion by Rac and Rho Small G Proteins in MDCK Cells

Abstract: The Rho small G protein family, consisting of the Rho, Rac, and Cdc42 subfamilies, regulates various cell functions, such as cell shape change, cell motility, and cytokinesis, through reorganization of the actin cytoskeleton We show here that the Rac and Rho subfamilies furthermore regulate cell–cell adhesion We prepared MDCK cell lines stably expressing each of dominant active mutants of RhoA (sMDCK-RhoDA), Rac1 (sMDCK-RacDA), and Cdc42 (sMDCK-Cdc42DA) and dominant negative mutants of Rac1 (sMDCK-RacDN) and Cdc42 (sMDCK-Cdc42DN) and analyzed cell adhesion in these cell lines The actin filaments at the cell–cell adhesion sites markedly increased in sMDCK-RacDA cells, whereas they apparently decreased in sMDCK-RacDN cells, compared with those in wild-type MDCK cells Both E-cadherin and β-catenin, adherens junctional proteins, at the cell–cell adhesion sites also increased in sMDCK-RacDA cells, whereas both of them decreased in sMDCK-RacDN cells The detergent solubility assay indicated that the amount of detergent-insoluble E-cadherin increased in sMDCK-RacDA cells, whereas it slightly decreased in sMDCK-RacDN cells, compared with that in wild-type MDCK cells In sMDCK-RhoDA, -Cdc42DA, and -Cdc42DN cells, neither of these proteins at the cell–cell adhesion sites was apparently affected ZO-1, a tight junctional protein, was not apparently affected in any of the transformant cell lines Electron microscopic analysis revealed that sMDCK-RacDA cells tightly made contact with each other throughout the lateral membranes, whereas wild-type MDCK and sMDCK-RacDN cells tightly and linearly made contact at the apical area of the lateral membranes These results suggest that the Rac subfamily regulates the formation of the cadherin-based cell– cell adhesion Microinjection of C3 into wild-type MDCK cells inhibited the formation of both the cadherin-based cell–cell adhesion and the tight junction, but microinjection of C3 into sMDCK-RacDA cells showed little effect on the localization of the actin filaments and E-cadherin at the cell–cell adhesion sites These results suggest that the Rho subfamily is necessary for the formation of both the cadherin-based cell– cell adhesion and the tight junction, but not essential for the Rac subfamily-regulated, cadherin-based cell– cell adhesion

Bidentate Directing Groups: An Efficient Tool in C-H Bond Functionalization Chemistry for the Expedient Construction of C-C Bonds.

Abstract: During the past decades, synthetic organic chemistry discovered that directing group assisted C–H activation is a key tool for the expedient and siteselective construction of C–C bonds. Among the v...

LDV measurements of an air-solid two-phase flow in a vertical pipe

Abstract: Measurements of air and solid-particle velocities were made in a vertical pipe two-phase flow by the use of a laser-Doppler velocimeter (LDV). Five kinds of plastic particles, diameters of which ranged from about 3 mm to 200 μm, were transported in a vertical pipe of 30 mm inner diameter. It was found that, the smaller the particle size, the flatter was the mean air velocity distribution for the same mass flow ratio of solids to air. Large particles increased air turbulence throughout the pipe section, while small particles reduced it. Both effects of promotion and suppression of turbulence were observed at the same time in the presence of particles of medium size, that is, the turbulence was increased around the pipe centre and reduced near the wall. The frequency spectrum of air turbulence normalized by the turbulence intensity was not changed by the large particles. In the presence of the small particles, the higher-frequency parts of the spectrum increased.

An adipocyte-derived plasma protein, adiponectin, adheres to injured vascular walls.

Abstract: Adipose tissue secretes a variety of proteins into the bloodstream. We have previously reported a novel cDNA, apM1 (adipose most abundant gene transcript 1), which is specifically and abundantly expressed in adipose tissue [1]. Primary structure analysis predicted that the apM1 gene product possesses significant homology to collagens VIII, X and complement factor C1q, and we named it adiponectin. In the current study, we analyzed characteristics of adiponectin in vitro and in vivo. Adiponectin protein was proved to be secreted into the medium when the cDNA was transfected to COS cells. Anti-adiponectin cross-reactivities were abundantly detected in the human plasma. In solid-phase binding assays, adiponectin specifically bound to collagen types I, III and V, which are present in vascular intima. Immunohistochemical analysis revealed that adiponectin was detected in the walls of the catheter-injured vessels but not in the intact vascular walls. These data suggest that adiponectin is a plasma protein produced by adipose tissue and accumulates in vascular walls when the endothelial barrier is injured.

Nectin and afadin: novel organizers of intercellular junctions.

Abstract: The cadherin superfamily plays key roles in intercellular adhesion. An emerging intercellular adhesion system, consisting of nectin and afadin, also has roles in organization of a variety of intercellular junctions either in cooperation with, or independently of, cadherin. Nectin is a Ca(2+)-independent immunoglobulin-like intercellular adhesion molecule, and afadin is a nectin- and actin-filament-binding protein that connects nectin to the actin cytoskeleton. This novel intercellular adhesion system has roles in the organization of E-cadherin-based adherens junctions and claudin-based tight junctions in epithelial cells. The adhesion system is furthermore involved in the formation of synapses in neurons and the organization of heterotypic junctions between Sertoli cells and spermatids in the testis.