Hsp90 induces increased genomic instability toward DNA-damaging agents by tuning down RAD53 transcription.
It is well documented that elevated body temperature causes tumors to regress upon radiotherapy. However, how hyperthermia induces DNA damage sensitivity is not clear. We show that a transient heat shock and particularly the concomitant induction of Hsp90 lead to increased genomic instability under DNA-damaging conditions. Using Saccharomyces cerevisiae as a model eukaryote, we demonstrate that elevated levels of Hsp90 attenuate efficient DNA damage signaling and dictate preferential use of the potentially mutagenic double-strand break repair pathway. We show that under normal physiological conditions, Hsp90 negatively regulates RAD53 transcription to suppress DNA damage checkpoint activation. However, under DNA damaging conditions, RAD53 is derepressed, and the increased level of Rad53p triggers an efficient DNA damage response. A higher abundance of Hsp90 causes increased transcriptional repression on RAD53 in a dose-dependent manner, which could not be fully derepressed even in the presence of DNA damage. Accordingly, cells behave like a rad53 loss-of-function mutant and show reduced NHEJ efficiency, with a drastic failure to up-regulate RAD51 expression and manifestly faster accumulation of CLN1 and CLN2 in DNA-damaged G1, cells leading to premature release from checkpoint arrest. We further demonstrate that Rad53 overexpression is able to rescue all of the aforementioned deleterious effects caused by Hsp90 overproduction.
Department of Biotechnology and Bioinformatics, University of Hyderabad, Hyderabad 500046, India.
Nidhi
N
Khurana
Department of Biotechnology and Bioinformatics, University of Hyderabad, Hyderabad 500046, India.
Shyamasree
S
Laskar
Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad 500046, India.
Mrinal K
MK
Bhattacharyya
Department of Biotechnology and Bioinformatics, University of Hyderabad, Hyderabad 500046, India sdeb70@gmail.com.
Sunanda
S
Bhattacharyya
D002453:Cell Cycle / Q000235:genetics; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D064447:Checkpoint Kinase 2 / Q000235:genetics / Q000378:metabolism*; D016213:Cyclins / Q000378:metabolism; D004247:DNA / Q000378:metabolism; D004249:DNA Damage; D004260:DNA Repair; D005334:Fever / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal / Q000235:genetics; D042822:Genomic Instability / Q000502:physiology; D018841:HSP90 Heat-Shock Proteins / Q000235:genetics / Q000378:metabolism*; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D051135:Rad51 Recombinase / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D015533:Transcriptional Activation
C082719:CLN1 protein, S cerevisiae; C082721:CLN2 protein, S cerevisiae; D018797:Cell Cycle Proteins; D016213:Cyclins; C074510:HSP82 protein, S cerevisiae; D018841:HSP90 Heat-Shock Proteins; D029701:Saccharomyces cerevisiae Proteins; D004247:DNA; D011494:Protein Kinases; D064447:Checkpoint Kinase 2; D017346:Protein Serine-Threonine Kinases; C067022:RAD53 protein, S cerevisiae; C495151:RAD51 protein, S cerevisiae; D051135:Rad51 Recombinase