Influence of collagen gel on the orientation of epithelial cell polarity: follicle formation from isolated thyroid cells and from preformed monolayers.

Abstract

The influence of collagen gels on the orientation of the polarity of epithelial thyroid cells in culture was studied under four different conditions . (a) Isolated cells cultured on the surface of a collagen gel formed a monolayer. The apical pole was in contact with the culture medium and the basal membrane was attached to the substratum .(b) Isolated cells embedded inside the gel organized within 8 d into follicles . The basal pole was in contact with collagen and the apical pole was oriented towards the interior of the follicular lumen .(c) Cells were first organized into floating vesicles, structures in which the apical surface is in contact with the culture medium, and the vesicles were embedded inside the collagen gel . After 3 d, cell polarity was inverted, the apical pole being oriented towards the cavity encompassed by cells . Vesicles had been transformed into follicles.(d) Monolayers formed on collagen gels as in a were overlaid with a second layer of collagen, which was polymerized in contact with the apical cell surface. A disorganization of the continuous pavement occurred within 24 h; cells attached to the upper layer of collagen and reorganized into follicles in the collagen sandwich within 4-8 d .A similar process occurred when the monolayer was grown on plastic and overlaid with collagen, or grown on collagen and covered with small pieces of glass cover slips. No reorganization was observed between two glass surfaces .In conclusion, first, a basal pole was always formed in the area of contact between the cell membrane and an adhesive surface and, second, the interaction of a preformed apical pole with an adhesive surface was not compatible with the stability of this domain of the plasma membrane . The interaction of the cell membrane with extracellular components having adhesive properties appears to be a determinant factor in the orientation and stabilization of epithelial cell polarity .The formation of a polarized epithelial cell monolayer involves two types of events : (a) the formation of intercellular junctions, the most typical for epithelia being the tight junction (14, 36) ; and (b) cell polarization by an asymmetrical distribution of membrane components between the apical and basolateral domains (8,21) and by a polar distribution of intracellular

Fine structural aspects of follicle-like cavity formation from dispersed porcine thyroid cells cultured in a collagen substrate.

“…The inverted thyroid follicles cultured inside collagen gel revert to normal follicles (CHAMBARD et al, 1981(CHAMBARD et al, , 1984, or form compact spheroids with small lumina (GARBI et al, 1986). In all cases, including our results, the cell surfaces in contact with collagen lose microvilli and turn basal.…”

“…The cell surface which is in contact with collagen shows characteristics of the basal pole, as CHAMBARD et al (1981) reported. RoDRIGUEZ-BoULAN and his co-workers (1983) reported that the cell-collagen contact triggers the polarized budding of viruses when Madin-Darby canine kidney (MDCK) cells are infected with enveloped viruses such as influenza and vesicular stomatitis viruses.…”

“…1) When the follicle epithelial cells of the thyroid isolated by enzymatic treatment were cultured on a plastic culture dish, they form, within 2-3 days of culture , a monolayer of flattened polygonal cells as reported by CHAMBARD et al (1981) (Fig. 1).…”

Identification of thyroglobulin domain(s) involved in cell-surface binding and endocytosis

“…Porcine thyroid cells were isolated from fresh thyroid glands by discontinuous trypsin-EGTA treatment (Chambard et al 1981). Inside-out follicles were obtained as described previously (Espanet et al 1992, Giraud et al 1997.…”

Fine structural aspects of inverted follicles in cultured porcine thyroids.

“…All these studies have succeeded in making reversed follicles by digestion of interfollicular connective tissue elements, which are considered to be an important factor in keeping cell polarity. CHAMBARD et al (1981) reported that the interaction of the cell membrane with extracellular components having adhesive properties appears to be a determinant factor in the orientation and stabilization of epithelial cell polarity.…”