Association of alpha-dystrobrevin with reorganizing tight junctions.
Alpha-dystrobrevin (alpha-DB) has been described primarily as a cytoplasmic component of the dystrophin-glycoprotein complex in skeletal muscle cells. Isoforms of alpha-DB show different localization in cells and tissues; at basolateral membranes in epithelial cells, dystrobrevins mediate contact with the extracellular matrix, peripheral and transmembrane proteins and the filamentous actin cytoskeleton. Beside their structural role, alpha-DBs are assumed to be important in cell signalling and cell differentiation. We have primarily assessed the role of alpha-DB in two epithelial cell lines (MDCK I, HT 29), which represent different developmental stages and exhibit distinct permeability characteristics. Using a polyclonal anti-alpha-DB antibody, we have investigated its expression, localization and association with tight junction (TJ)- associated proteins (ZO-1, occludin) before and after protein kinase C (PKC) activation with phorbol myristate acetate. Distinct subsets of alpha-DB isoforms were detected in the two cell lines by immunoblotting. In both cell lines there was submembranous localization of alpha-DB both apically and basolaterally, shown with confocal imaging. PKC activation caused a reorganization of TJ, which was parallel to increased localization of alpha-DB to TJ areas, most pronounced in MDCK I cells. Moreover, actin and ZO-1 co-immunoprecipitated with a-DB, as displayed with immunoblotting. Our findings suggest that a-dystrobrevin specifically is associated with the tight junctions during their reorganization.
Sjö
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Division of Medical Microbiology, Department of Molecular and Clinical Medicine, Faculty of Health Sciences, Linköping University, Linköping, 581 85, Sweden. anisj@imk.liu.se
Magnusson
K E
KE
Peterson
K H
KH
D000818:Animals; D018938:Caco-2 Cells; D002460:Cell Line; D004285:Dogs; D049029:Dystrophin-Associated Proteins / Q000096:biosynthesis*; D005455:Fluorescent Antibody Technique; D019073:HT29 Cells; D006801:Humans; D018374:LLC-PK1 Cells; D008565:Membrane Proteins / Q000096:biosynthesis; D018613:Microscopy, Confocal; D009479:Neuropeptides / Q000096:biosynthesis*; D062793:Occludin; D010750:Phosphoproteins / Q000096:biosynthesis; D010766:Phosphorylation; D020033:Protein Isoforms / Q000096:biosynthesis; D013552:Swine; D019108:Tight Junctions / Q000502:physiology*; D062826:Zonula Occludens-1 Protein
C490915:DTNA protein, human; D049029:Dystrophin-Associated Proteins; D008565:Membrane Proteins; D009479:Neuropeptides; C568985:OCLN protein, human; D062793:Occludin; D010750:Phosphoproteins; D020033:Protein Isoforms; C569042:TJP1 protein, human; D062826:Zonula Occludens-1 Protein