Increased levels of UV-induced protease activity in human UVAP-1 cells exposed to gravity-changing stress: involvement of E-64-sensitive proteases in suppression of UV mutagenicity

Authors

  • Shunji Takahashi,

    1. Department of Environmental Biochemistry, Graduate School of Medicine, Chiba University, Inohana 1-8-1, Chuoku, Chiba 260-8670, Japan
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  • Hong-Chang Zhang,

    1. Department of Environmental Biochemistry, Graduate School of Medicine, Chiba University, Inohana 1-8-1, Chuoku, Chiba 260-8670, Japan
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  • Ritsuko Hasegawa,

    1. Department of Environmental Biochemistry, Graduate School of Medicine, Chiba University, Inohana 1-8-1, Chuoku, Chiba 260-8670, Japan
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  • Kiyonobu Karata,

    1. Department of Environmental Biochemistry, Graduate School of Medicine, Chiba University, Inohana 1-8-1, Chuoku, Chiba 260-8670, Japan
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  • Kazuko Kita,

    1. Department of Environmental Biochemistry, Graduate School of Medicine, Chiba University, Inohana 1-8-1, Chuoku, Chiba 260-8670, Japan
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  • Chieko Wano,

    1. Department of Environmental Biochemistry, Graduate School of Medicine, Chiba University, Inohana 1-8-1, Chuoku, Chiba 260-8670, Japan
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  • Yoshitaka Yamaguchi,

    1. Department of Plastic and Reconstructive Surgery, Graduate School of Medicine, Chiba University, Inohana 1-8-1, Chuoku, Chiba 260-8670, Japan
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  • Shigeru Sugaya,

    1. Department of Environmental Biochemistry, Graduate School of Medicine, Chiba University, Inohana 1-8-1, Chuoku, Chiba 260-8670, Japan
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  • Jun Nomura,

    1. Department of Environmental Biochemistry, Graduate School of Medicine, Chiba University, Inohana 1-8-1, Chuoku, Chiba 260-8670, Japan
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  • Masaharu Ichinose,

    1. Department of Plastic and Reconstructive Surgery, Graduate School of Medicine, Chiba University, Inohana 1-8-1, Chuoku, Chiba 260-8670, Japan
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  • Nobuo Suzuki

    Corresponding author
    1. Department of Environmental Biochemistry, Graduate School of Medicine, Chiba University, Inohana 1-8-1, Chuoku, Chiba 260-8670, Japan
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Corresponding author. Tel.: +81-43-226-2041; fax: +81-43-226-2041 nobuo@med.m.chiba-u.ac.jp

Abstract

Under the 1 G condition, the increase in antipain-sensitive protease activity promptly after UV (mainly 254 nm wavelength) irradiation in cultured human cells is detected and found to be one of the intriguing events involved in suppression of cell mutability. It was found that two cell lines, RSa and its variant UVAP-1 cells are applicable; the former is hypermutable and not susceptible to protease activation, while the latter is hypomutable and susceptible. In the present study it was investigated whether the increase in protease activity by UV irradiation is also observed in hypomutable human UVAP-1 cells exposed to gravity-changing stress and whether the increase is involved in suppression of UV mutagenicity. Exposure of human UVAP-1 cells to gravity-changing stress such as free-fall and parabolic flight prior to UV irradiation resulted in a pronounced increase in protease activity, but not to hypergravity conditions (2 and 10 G) prior to UV irradiation. To characterize the proteases, components of lysates from the cells exposed to free-fall prior to UV irradiation were fractionated by high performance liquid chromatography, indicating two separate fractions with highly increased levels of E-64-sensitive protease activity. In the cells treated with E-64 during their exposure to free-fall, K-ras codon 12 base substitution mutation was detected after UV irradiation, although the mutation was not detected after UV irradiation alone. Thus, the increase in E-64-sensitive protease activity may be involved in the suppression of UV mutagenicity in UVAP-1 cells exposed to free-fall.

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