Changes in some cytoskeletal proteins during neuroblastoma cell differentiation.

After in vitro microtubule assembly of mouse neuroblastoma crude extracts, six protein species migrate in the tubulin region of two-dimensional electrophoregrams. The evolution of these forms after morphological cell differentiation of the clone NIE115 shows two major modifications. Form 5 decreased drastically while form 6 increases during neurite formation. Peptide mapping analysis reveals that forms 5 and 6 are vimentin, a component of intermediate filaments, and beta-tubulin subunit, respectively. Sodium butyrate treatment of NIE115 cells or serum starvation of NIA103 cells, conditions blocking cell division and failing to induce morphological differentiation, prevent any modifications in the relative proportion of these proteins. It is concluded that the changes in the distribution of the tubulin isoforms and vimentin are directly related to neurite formation.

Evidence for ionic coupling between MDCK cells at non-confluent and confluent stages of culture.

The possibility of current flow between epithelial cells (MDCK) has been evaluated using intracellular electrophysiological techniques. We report here that a significant electrotonic coupling was found in this material at all ages of culture. This observation contrasts with previous reports that confluent MDCK are not ionically coupled and lack gap junctions. Alternative mechanisms for such coupling are considered, with emphasis on the role of tight junctions, should the absence of gap junctions be confirmed.

[Morphological differentiation of neuroblastoma by 1 methyl cyclohexane carboxylic acid (CCA) and some C1 derivatives]. / Différenciation morphologique du neuroblastome par l'acide 1 méthyl cyclohexane carboxylique (CCA) et certains dérivés en C1.

We describe the induction of neuroblastoma morphological differentiation by 1 methyl cyclohexane carboxylic acid (CCA) and by some C1 derivatives of CCA. This induction proceeds in a medium which allows, in the absence of inducer, a normal growth of neuroblastoma cells and contains 7.5% fetal Calf serum. In order to establish a clear-dose response relationship and to compare the relative potencies of different drugs, the morphological changes were assessed by examining "long neurite-bearing cells".

Potential pathogenic role of cell-surface polypeptides, cross-reactive with DNA, in systemic lupus erythematosus.

The authors report their studies on the cross-reactivity of certain anti-DNA antibodies with polypeptides expressed on the membrane of different cell types. These lupus associated membrane proteins (LAMPs) could play an important role in the pathophysiology of systemic lupus erythematosus (SLE) since anti-LAMP antibodies have been found in renal eluates of MRL/lpr/lpr mice and in the serum of patients with active SLE.