Role of polyamines during chromosome condensation of mammalian cells.

The objective of the present study was to investigate the role of polyamines in the process of chromosome condensation. The phenomenon of premature chromosome condensation (PCC) involving fusion between mitotic and interphase cells was used as the assay system. The factors present in the mitotic cells would bring about the breakdown of the nuclear membrane and condensation of the interphase chromatin into chromosomes, similar to that which occurs during the initiation of mitosis. Alpha-difluoromethyl ornithine (DFMO), a specific irreversible inhibitor of ornithine decarboxylase was used to deplete both mitotic and interphase cells of polyamines. The results indicate that the polyamine depleted mitotic cells have a diminished ability to induce PCC. This inhibition could easily be reversed by exogenous addition of polyamines at the time of fusion. Furthermore, exogenously added polyamines hastened the entry of exponentially growing cells into mitosis. These observations suggest an essential role for polyamines during the process of chromosome condensation of mammalian cells.