Overexpression of cyclin A in human HeLa cells ind

Authors: Ron Balczon

Publish Date: 2014/03/14

Volume: 110, Issue: 6, Pages: 381-392

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Abstract

The combination of hydroxyurea HU and caffeine has been used for inducing kinetochore dissociation from mitotic chromosomes and for causing centrosome/spindle pole amplification However these effects on microtubule organizing centers MTOCs are limited to certain cell types It was reasoned that if the biochemical differences in MTOC behavior between cells following HU treatment could be identified then critical information concerning the regulation of these organelles would be obtained During these studies it was determined that cells from hamster rat and deer could be induced to enter mitosis with dissociated kinetochores and to synthesize centrosomes during arrest with HU while cells from human and mouse could not Comparisons between human HeLa cells and CHO cells determined that cyclin A levels were depressed in HeLa cells relative to CHO cells following HU addition Overexpression of cyclin A in HeLa cells converted them to a cell type capable of detaching kinetochores from mitotic chromosomes Ultrastructural analyses determined that the detached human kinetochores exhibited a normal platelike morphology and appeared capable of associating with microtubules In addition HeLa cells overexpressing cyclin A also overproduced spindle poles during HU arrest demonstrating that cyclin A activity also is important for centrosome replication during interphase In summary elevated cyclin A levels are important for the capacity of cells to be driven into mitosis by caffeine addition for the ability of cells to progress to mitosis with detached kinetochores and for centrosome/spindle pole replication

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