title: Intracellular events are responsible for the differential expression of fibronectin on the fibroblast surface during chick embryo development.
abstract: We previously showed that differences in the adhesive behaviour of fibroblasts obtained from 8-day-old (8-day CEF) and 16-day-old chick embryos (16-day CEF) were not due to alterations of cell surface fibronectin receptors. Herein we show that fibronectin (FN) was expressed more rapidly on the 8-day CEF surface (30 min) than on the 16-day CEF surface (60 min). In order to elucidate the mechanism responsible for these differences in the expression of cell surface FN we investigated the biosynthesis and the post-translational modifications of FN in 8- and 16-day CEF. Pulse-chase experiments revealed that FN was processed more slowly to an endo-beta-N-acetylglucosaminidase H (endo H)-resistant form in 16-day CEF than in 8-day CEF, whereas the kinetic of FN biosynthesis was similar in both cell populations. This difference was not related to a differential retention of FN in endoplasmic reticulum (ER) as determined after saponin-permeabilization. These results suggested that the rate-limiting step in the transport of FN to the cell surface in 16-day cells occurred between the ER and the medial part of the Golgi apparatus. It seems that the delay in the processing of endo H-resistant N-glycans was sufficient to account for differences between 8- and 16-day CEF in the rate of surface expression of FN and CEF adhesion to a plastic substratum.
authors.affiliation: INSERM U 180, U.F.R. Biomédicale des Saints-Pères, Paris, France.
authors.forename: J
authors.initials: J
authors.lastname: Botti
authors.forename: E
authors.initials: E
authors.lastname: Gouet
authors.forename: M
authors.initials: M
authors.lastname: Aubery
authors.forename: P
authors.initials: P
authors.lastname: Codogno
mesh_terms: D000818:Animals; D002448:Cell Adhesion / Q000502:physiology; D002462:Cell Membrane / Q000378:metabolism; D002478:Cells, Cultured; D002642:Chick Embryo; D004591:Electrophoresis, Polyacrylamide Gel; D004721:Endoplasmic Reticulum / Q000378:metabolism; D005347:Fibroblasts / Q000166:cytology / Q000378:metabolism*; D005353:Fibronectins / Q000096:biosynthesis / Q000378:metabolism*; D006056:Golgi Apparatus / Q000378:metabolism; D006596:Hexosaminidases / Q000378:metabolism; D007700:Kinetics; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase; D011233:Precipitin Tests; D012503:Saponins / Q000494:pharmacology
chemical_list: D005353:Fibronectins; D012503:Saponins; D006596:Hexosaminidases; D017038:Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase