serum factors induced the nuclear location of annexin v in the human osteosarcoma cell line (mg-63)

calcium-binding proteins play essential roles in the cell. one important class of calcium-binding proteins is the annexin family. this is a family of 13 proteins, which binds to phospholipids in a calcium-dependent manner. osteosarcoma cell line (mg-63) is a transformed cell that has many characteristics of the differentiated cell, such as a considerable serum dependency in its growth rate. using specific antibodies against each annexin and immunoflurescence microscopy, the location and relocation of the annexin v was determined by some serum factors. serum starvation of mg-63 cells increases their doubling time from 24 hours to 4 days. cells grown in serum contain high levels of annexin v in the cell nucleus whereas in the absence of serum results in loss of nuclear annexin v in about 75% of the cells. refeeding cells with medium containing 10% serum restore annexin v to the nuclei within 5 hours. charcoal-treated serum cannot allow annexin v to return to the nucleus. inhibition of protein synthesis with cycloheximide does not prevent the serum-induced return of annexin v to the nuclei. however, treatment of cells with genistein at a concentration specific for inhibition of tyrosine kinases (200 m) inhibits the relocation of annexin v from cytoplasm to the nucleus. thus, the cellular location of the annexin v depends on the growth state of the cells. it can be altered by the movement of this protein between the cytosol and the nucleus.