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DNA cleavage and Trp53 differentially affect SINE transcription
Author(s) -
Hagan Christy R.,
Rudin Charles M.
Publication year - 2007
Publication title -
genes, chromosomes and cancer
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.754
H-Index - 119
eISSN - 1098-2264
pISSN - 1045-2257
DOI - 10.1002/gcc.20406
Subject(s) - biology , dna damage , transcription (linguistics) , etoposide , sine , genome instability , downregulation and upregulation , alu element , dna , topoisomerase , microbiology and biotechnology , genetics , gene , genome , human genome , linguistics , philosophy , geometry , mathematics , chemotherapy
Among the cellular responses observed following treatment with DNA‐damaging agents is the activation of Short Interspersed Elements (SINEs; retrotransposable genetic elements that comprise over 10% of the human genome). By placing a human SINE (the Alu element) into murine cells, we have previously shown that DNA‐damaging agents such as etoposide can induce both upregulation of SINE transcript levels and SINE retrotransposition. A similarly cytotoxic (but not genotoxic) exposure to vincristine was not associated with SINE activation. Here we demonstrate that multiple other genotoxic exposures are associated with upregulation of SINE transcript levels. By comparing the effects of similarly cytotoxic doses of the topoisomerase II inhibitors etoposide and merbarone, we confirm that DNA strand breakage is specifically associated with SINE induction. By evaluating transcription rate and RNA stability, we demonstrate that SINE induction by genotoxic exposure is associated with transcriptional induction and not with transcript stabilization. Finally we demonstrate that SINE induction by genotoxic stress is mediated by a Trp53‐independent pathway, and in fact that Trp53 plays an inhibitory role in attenuating the transcriptional induction of SINE elements following exposure to a genotoxic agent. Together these data support a model in which initial DNA damage can trigger genomic instability due to SINE activation, a response which may be amplified in cancer cells lacking functional TP53. © 2006 Wiley‐Liss, Inc.