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Ultraviolet light attenuates heat-inducible gene expression
L Qiu1, J F Welk, D A Jurivich
1Department of Veteran Affairs, VA Chicago Health Care System, Illinois, USA.
Journal of Cellular Physiology
|September 1, 1997
Summary
Ultraviolet light (UV) disrupts the heat shock response by affecting heat shock factor 1 (HSF1) phosphorylation. This UV-induced stress response uncouples heat shock gene expression, with implications for cellular stress mechanisms.
Area of Science:
- Cellular stress response
- Molecular biology
- Biochemistry
Background:
- Ultraviolet light (UV) activates transcription factors like NF-kB and AP-1.
- The impact of UV on heat shock factor 1 (HSF1) and its role in stress gene expression remains largely unknown.
Purpose of the Study:
- To investigate the effect of UV radiation on HSF1 activity and the heat shock response.
- To elucidate the molecular mechanisms underlying UV-induced uncoupling of thermal stress gene expression.
Main Methods:
- Analysis of UV-treated HeLa cells and fibroblasts.
- Assessing HSF1 DNA binding, multimerization, and nuclear translocation.
- Investigating HSF1 phosphorylation patterns using phosphopeptide mapping.
- Evaluating the role of MAP kinase pathways and antioxidants like N-acetyl cysteine.
Main Results:
- UV exposure weakly induced HSF1 DNA binding but significantly attenuated heat-inducible gene expression.
- UV-induced hyperphosphorylation of monomeric HSF1 was observed, distinct from heat-induced phosphorylation.
- Antioxidant treatment partially restored heat shock gene expression.
- MAP kinase pathway inhibitors did not prevent UV-induced HSF1 phosphorylation.
Conclusions:
- UV radiation uncouples the heat shock response, potentially through phosphorylation of monomeric HSF1.
- The mechanism involves steps beyond those typically associated with heat shock factor activation.
- Further research is needed to fully understand UV's impact on HSF1 and cellular stress pathways.