AT-hook proteins stimulate induction of senescence markers triggered by 5-bromodeoxyuridine in mammalian cells.
5-Bromodeoxyuridine (BrdU) induces a phenomenon similar to cellular senescence in mammalian cells. To address an underlying molecular mechanism in this phenomenon, we assessed the role of AT-hook proteins that bind to the minor grooves of specific AT-rich sequences. We expressed DsRed-tagged HMGI, MATH2, and MATH20 proteins in HeLa cells in a doxycycline dependent manner. Modest expression of these proteins revealed no apparent effect on the cells although high levels of expression were toxic to the cells. In contrast, their modest expression in the presence of low concentrations of BrdU similarly and dose-dependently induced senescence markers examined, although the same concentrations of BrdU alone showed no obvious effect. In both cases, DsRed fluorescence was mainly observed as foci or intense dots on Hoechst 33342-staining regions. These distribution patterns were not changed by addition of BrdU. Since AT-hook domains can displace chromatin compacting proteins pre-bound on AT-rich sequences, these results suggest that chromatin unpacking is one of the factors stimulating expression of the senescence markers in human cells.
Satou
Wataru
W
Kihara Institute for Biological Research and Graduate School of Integrated Science, Yokohama City University, Maioka-cho 641-12, Yokohama 244-0813, Japan.
Suzuki
Toshikazu
T
Noguchi
Takeharu
T
Ogino
Hideki
H
Fujii
Michihiko
M
Ayusawa
Dai
D
D024761:AT-Hook Motifs; D015415:Biomarkers / Q000032:analysis; D015152:Blotting, Northern; D001973:Bromodeoxyuridine / Q000494:pharmacology*; D002455:Cell Division / Q000187:drug effects; D016922:Cellular Senescence / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D025741:HMGA1a Protein / Q000235:genetics / Q000378:metabolism*; D006367:HeLa Cells; D006801:Humans; D011485:Protein Binding; D014162:Transfection
D015415:Biomarkers; D025741:HMGA1a Protein; D001973:Bromodeoxyuridine