title: Effect of space flight on the frequency of micronuclei and expression of stress-responsive proteins in cultured mammalian cells.
abstract: Results of past space experiments suggest that the biological effect of space radiation could be enhanced under microgravity in some cases, especially in insects. To examine if such a synergistic effect of radiation and microgravity also exists in human cells, frequencies of chromosome instability and cellular levels of several stress-responsive proteins were analyzed in cultured human and rodent cells after space flight. Human (MCF7 and AT2KY), mouse (m5S) and hamster (SHE) cell lines were loaded on the Space Shuttle Discovery (STS-95 mission) and grown during a 9-day mission. After landing, the micronuclei resulting from abnormal nuclear division and accumulation of stress-responsive proteins such as p53 and mitogen-activated protein kinases (MAPKs), which are involved in radiation-induced signal transduction cascades, were analyzed. The frequencies of micronuclei in all the four mammalian cell strains tested were not significantly different between flight and ground control samples. Also, the cellular amounts of p53, p21 (WAF1/SDI1/CIP1) and activated (phosphorylated) forms of three distinct MAPKs in MCF7 and m5S cells of flight samples were similar to those of ground control samples. These results indicated that any effect of space radiation, microgravity, or combination of both were not detectable, at least under the present experimental conditions.
authors.affiliation: Radiation Biology Center, Kyoto University, Yoshida-konoecho, Sakyo-ku, Kyoto 606-8501, Japan. ikenaga7@f6.dion.ne.jp
authors.forename: Mituo
authors.initials: M
authors.lastname: Ikenaga
authors.forename: Jun
authors.initials: J
authors.lastname: Hirayama
authors.forename: Tomohisa
authors.initials: T
authors.lastname: Kato
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Kitao
authors.forename: Zhen-Bo
authors.initials: ZB
authors.lastname: Han
authors.forename: Kanji
authors.initials: K
authors.lastname: Ishizaki
authors.forename: Kimiko
authors.initials: K
authors.lastname: Nishizawa
authors.forename: Fumio
authors.initials: F
authors.lastname: Suzuki
authors.forename: Thomas F
authors.initials: TF
authors.lastname: Cannon
authors.forename: Keiji
authors.initials: K
authors.lastname: Fukui
authors.forename: Toru
authors.initials: T
authors.lastname: Shimazu
authors.forename: Shigeki
authors.initials: S
authors.lastname: Kamigaichi
authors.forename: Noriaki
authors.initials: N
authors.lastname: Ishioka
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Matsumiya
mesh_terms: D000818:Animals; D002460:Cell Line; D002467:Cell Nucleus / Q000378:metabolism*; D006224:Cricetinae; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins / Q000378:metabolism*; D004789:Enzyme Activation; D006801:Humans; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010766:Phosphorylation; D013026:Space Flight; D013312:Stress, Physiological / Q000378:metabolism*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*
chemical_list: C493956:CDKN1A protein, human; C493957:Cdkn1a protein, mouse; D050759:Cyclin-Dependent Kinase Inhibitor p21; D016213:Cyclins; D016159:Tumor Suppressor Protein p53; D020928:Mitogen-Activated Protein Kinases