Characterization of Ca2+-dependent and -independent aggregation mechanisms among mouse cerebellar cells.
To gain insight into the cellular and molecular mechanisms underlying cell interactions in the early postnatal mouse cerebellum, Ca2+-dependent and -independent aggregation mechanisms were characterized using single cell suspensions under conditions that allow discrimination between the two mechanisms. When cerebellar cells were derived from newborn to 10-day-old mouse cerebellum, both mechanisms were active and showed no major change in activity during this time period. Mg2+ could not replace Ca2+ in the Ca2+-dependent mechanism. In contrast to the Ca2+-independent mechanisms, the Ca2+-dependent mechanism was inactive at low temperatures, suggesting a necessity for molecular rearrangement within the surface membrane during aggregation. Neuraminidase, chondroitinase, heparinase or hyaluronidase treatment of cells did not influence the aggregation of cells under Ca2+-dependent and -independent conditions. Chondroitin sulfate inhibited and hyaluronic acid stimulated the Ca2+-dependent mechanism, whereas chondroitin sulfate only slightly and hyaluronic acid strongly inhibited the Ca2+-independent one. Dextran sulfate slightly inhibited both mechanisms, whereas heparin and fucoidan, a complex sulfated carbohydrate, did not influence cell aggregation, while they strongly inhibited attachment of cells to laminin. The polycation poly-L-lysine slightly stimulated the Ca2+-independent mechanism, but inhibited the Ca2+-dependent one. Interestingly, chondroitin sulfate and hyaluronic acid strongly stimulated cell aggregation under conditions where both mechanisms were almost destroyed or inactive. Dextran sulfate showed only a small effect under these conditions. These observations indicate that different molecular mechanisms are active in cell-cell versus cell-extracellular matrix interactions and suggest a hitherto unknown complexity in molecular mechanisms during early postnatal cerebellar development.
Fischer
G
G
Department of Neurobiology, University of Heidelberg, F.R.G.
Schachner
M
M
D000375:Aging; D000818:Animals; D002118:Calcium / Q000494:pharmacology*; D002448:Cell Adhesion; D002449:Cell Aggregation / Q000187:drug effects*; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology / Q000187:drug effects / Q000254:growth & development*; D006025:Glycosaminoglycans / Q000494:pharmacology; D007700:Kinetics; D007797:Laminin / Q000502:physiology; D008274:Magnesium / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D009439:Neuraminidase / Q000494:pharmacology; D000509:alpha-Fetoproteins / Q000494:pharmacology
D006025:Glycosaminoglycans; D007797:Laminin; D000509:alpha-Fetoproteins; D009439:Neuraminidase; D008274:Magnesium; D002118:Calcium