Low gravity and integrins in cultured glial cells

We studied the effect of random rotation on the expression of integrins in cultured astrocytes with or without the addition of divalent ions. Some cultures were immediately fixed, others were let to rest and then fixed. Cells were submitted to immunohistochemistry using antibodies to α-tubulin, integrins, Ca^{2 +} ATPase and caspase-7. Labeling of F-actin, TUNEL method and scanning and transmission electron microscopy were also performed. The results showed that within 1 h of random rotation cytoskeleton was disorganized, cell division was impaired, and apoptosis were present. After 1 h, expression of integrins was evident and enhanced by calcium addition. Recovering of cell organization occurred after 1 h of rest. We may infer that prolonged modeled low G, a period of rest and addition of calcium ions stimulate integrins to cluster in focal contacts in order to have enough sticking capacity to adhere to the extra cellular matrix and allow internalization of divalent ions able to protect the inner compartment of the cell.