A Radiation-Induced Inhibitor of Chromosome Condensation and Nuclear Envelope Breakdown in HeLa Cells

• Published in: Radiation research 1992-11, Vol.132 (2), p.158-161
• Main Authors: Mikkelsen, R. B., Gentry, C.
• Format: Article
• Language: English
• Subjects: Animals; Caffeine - pharmacology; Cell cycle; Cell Cycle - radiation effects; Cell extracts; Cell Nucleus - physiology; Cell Nucleus - radiation effects; Chromosomes; Chromosomes, Human - radiation effects; Condensation; Cyclins; G2 Phase - drug effects; G2 Phase - radiation effects; HeLa Cells; Humans; Interphase; Irradiation; Kinetics; Mitosis; Mitosis - radiation effects; Nuclear Envelope - radiation effects; Nuclear Envelope - ultrastructure; Nuclear membrane; Oocytes - physiology; Oocytes - radiation effects; Space life sciences; Symposium: The Molecular Basis for Radiation Effects on Cell Progression through the Cell Cycle; Xenopus
• ISSN: 0033-7587; 1938-5404
• DOI: 10.2307/3578521

An in vitro microscopic assay for mitosis-inducing activity in mitotic HeLa cells was developed and used to demonstrate that cells irradiated and arrested in G2 phase of the cell cycle contain an inhibitor of mitosis. This assay system has a number of advantages over other assays including the use of autologous components (HeLa nuclei and mitotic cell extracts) in contrast to the microinjection method with Xenopus oocytes and without the requirements for microinjection expertise and Xenopus oocytes. The radiation-inducible inhibitor was detected at the lowest radiation dose tested (2 Gy) with maximal activity achieved within 30 min after radiation. Inhibitor activity decayed with time after radiation (2 Gy) with no activity detected at 6 h even though the cells remained in G2 phase, suggesting that either synthesis or activation of additional components is necessary for recovery from G2 arrest. The inhibitor activity was not detected in irradiated cells treated with caffeine to induce premature recovery from G2 arrest.