The beta 4 integrin subunit is expressed in mouse fibroblasts and modulated by transforming growth factor-beta 1.
Integrin beta 4 subunit is present in association with alpha 6 chain on both normal and transformed epithelial cells. Recently alpha 6 beta 4 heterodimer was found on the endothelium of medium-sized blood vessels and on immature thymocytes. In this report we show, by Northern blotting, indirect immunofluorescence, immunoprecipitation, and Western blotting, that beta 4 subunit is expressed also on cells of mesenchymal origin such as fibroblasts, myoblasts, and myotubes. Increased expression of alpha 6 beta 4 has been related to the aggressive metastatic phenotype of human and murine carcinomas. The transforming growth factor beta 1 (TGF-beta 1) has been found to modulate the expression of several integrins and intracellular matrix proteins, as well as to stimulate cell invasion and metastatic potential. To evaluate whether alpha 6 beta 4 expression is modulated by TGF-beta 1, we transfected 3T3 fibroblasts with an expression vector carrying the human TGF-beta 1 cDNA driven by the SV40 early promoter. We observed by indirect immunofluorescence a modification in the subcellular distribution of beta 4 subunit, which acquires a perinuclear localization. This finding suggests this integrin subunit correlates with the cytoskeletal reorganization induced by TGF-beta 1.
Scardigli
R
R
Molecular Oncogenesis Laboratory, Regina Elena Cancer Institute, C.R.S, Rome, Italy.
Soddu
S
S
Falcioni
R
R
Crescenzi
M
M
Cimino
L
L
Sacchi
A
A
D016475:3T3 Cells / Q000737:chemistry / Q000187:drug effects / Q000502:physiology; D000818:Animals; D000918:Antibody Specificity; D015703:Antigens, CD / Q000235:genetics* / Q000276:immunology; D001345:Autoradiography; D019084:Fluorescent Antibody Technique, Indirect; D015870:Gene Expression / Q000187:drug effects / Q000502:physiology; D039663:Integrin beta4; D016023:Integrins / Q000235:genetics*; D051379:Mice; D008807:Mice, Inbred BALB C; D011506:Proteins / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000494:pharmacology*
D015703:Antigens, CD; D039663:Integrin beta4; D016023:Integrins; D011506:Proteins; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta