Junctional modulation in mouse embryonal carcinoma cells by Fab fragments of rabbit anti-embryonal carcinoma cell serum.

Abstract

Mouse embryonal carcinoma P-CC4 cells are connected by extensive gap and tight junctions. When the cells are incubated in a medium containing Fab fragments against embryonal carcinoma F9 cells, they round up and a process of junctional removal is initiated. In particular, gap junctions are internalized and after 30 hr of incubation with the anti-F9 Fab fragments both tight and gap junctions are no longer present at the cell surface; however, the cells are still in contact by means of small attachment sites. Early stages of embryonic differentiation seem to be dependent upon relative position of individual blastomeres within the cleaving embryo and upon formation of microenvironmental domains (1-3). It is not known how positional information becomes operative. It is likely that developmental patterns are set by the acquisition of cell surface adhesion properties and by the assembly-modulation, at the right time, of intercellular junctions controlling both the metabolic cooperation between cells and the traffic of metabolites and ions along the paracellular routes of permeation (1-6). The formation of specific attachment sites and junctions accompanies the compaction of blastomeres at the eight-cell stage, which in turn triggers future segregation of presumptive cell types (2). The assumption that the surface features of the blastomere are crucial for compaction is also supported by the observation that this morphogenetic event in mouse preimplanted embryo may be prevented by the addition of Fab fragments from rabbit antiserum to embryonal carcinoma F9 cells (7,8). Anti-F9 Fab fragments can induce reversible decompaction when added to embryos up to the older morulae stage (8), and can block the metabolic coupling in embryonal carcinoma cell lines that are in mutual cooperation (7-9).The purpose of the present paper is to investigate whether anti-F9 Fab fragments are capable of modulating the junctional assemblies in the PCC4 embryonal carcinoma cell line in which "gap" and "tight" junctions are usually abundant. We have found that the addition of anti-F9 Fab fragments results in the loss of tight junctions and internalization of gap junctions. Further assembly of the same types of junctions is blocked after a 30-hr treatment of the cells with anti-F9 Fab fragments. MATERIALS AND METHODSThe embryonal carcinoma cell line PCC4/AzaR1 has been described (10). Rabbit anti-F9 serum, rabbit antiserum against embryonic mouse liver cells, and Fab preparations were produced according to the techniques described (8).Incubation with Anti-F9 Fab Fragments and Control Experiments. PCC4 cells growing in Dulbecco's modified Eagle's medium containing 15% fetal calf serum were suspended in phosphate-buffered saline. After dissociation, the cells were plated on Costar cluster plates in the same culture medium and allowed to grow for either 5 hr or 24 hr to the same final cell density. The anti-F9 Fab fragments (final concentration of 220 ,ug/ml) were added at these times, and the cells were allowed to grow in the presence of...

Fate of intercellular junctions in isolated adult rat cardiac cells.

“…Enclosed gap junctional structures have been observed in other tissues after dissociation (cf. Larsen, 1977Larsen, , 1983, in dissociated carcinoma cells (Dunia et al, 1979), and during differentiation (cf. Ginzberg and Gilula, 1979), and have been similarly interpreted as repCirculation Research/Vol.…”

Rapid rounding of human epidermoid carcinoma cells A-431 induced by epidermal growth factor

“…Cells grown in monolayer culture may become rounded in response to a wide variety of substances . These include hormones, cyclic nucleotides (23,28,29,31,43), proteases (12,32,36), and antisera raised against membrane proteins (13,41,42). In addition, cells normally round up during mitosis.…”

Isolation and characterization of peanut agglutinin‐resistant embryonal carcinoma cell‐surface variants

“…Antisera that react specifically with embryonic cells inhibit compaction of the blastomeres in the 8-16 cell mouse embryo (Kemler et al, 1977;Ducibella, 1980). One of these antisera also inhibits aggregation of embryonal carcinoma (EC) cells (Dunia et al, 1979), as does a mannose-containing oligosaccharide that binds to an uncharacterized endogenous lectin on these cells (Grabel et al, 1979). Although these observations suggest that the molecules recognized by the inhibitors mediate cell recognition andor adhesiveness, other interpretations are possible.…”