Hyperosmolality in the form of elevated NaCl but not urea causes DNA damage in murine kidney cells.
This study demonstrates, by using neutral comet assay and pulsed field gel electrophoresis, that hyperosmotic stress causes DNA damage in the form of double strand breaks (dsb). Different solutes increase the rate of DNA dsb to different degrees at identical strengths of hyperosmolality. Hyperosmolality in the form of elevated NaCl (HNa) is most potent in this regard, whereas hyperosmolality in the form of elevated urea (HU) does not cause DNA dsb. The amount of DNA dsb increases significantly as early as 15 min after the onset of HNa. By using neutral comet and DNA ladder assays, we show that this rapid induction of DNA damage is not attributable to apoptosis. We demonstrate that renal inner medullary cells are able to efficiently repair hyperosmotic DNA damage within 48 h after exposure to hyperosmolality. DNA repair correlates with cell survival and is repressed by 25 microM LY294002, an inhibitor of DNA-activated protein kinases. These results strongly suggest that the hyperosmotic stress resistance of renal inner medullary cells is based not only on adaptations that protect cellular proteins from osmotic damage but, in addition, on adaptations that compensate DNA damage and maintain genomic integrity.
Kültz
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Whitney Laboratory, University of Florida, 9505 Ocean Shore Boulevard, St. Augustine, FL 32086, USA. dkkw@whitney.ufl.edu
Chakravarty
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D000818:Animals; D017209:Apoptosis; D002460:Cell Line; D004249:DNA Damage; D004260:DNA Repair; D051747:DNA-Activated Protein Kinase; D004268:DNA-Binding Proteins; D007668:Kidney / Q000166:cytology; D007700:Kinetics; D051379:Mice; D009994:Osmolar Concentration; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D012965:Sodium Chloride / Q000378:metabolism*; D013997:Time Factors; D014508:Urea / Q000378:metabolism*; D014882:Water-Electrolyte Balance / Q000502:physiology*
D004268:DNA-Binding Proteins; D012965:Sodium Chloride; D014508:Urea; D051747:DNA-Activated Protein Kinase; D017346:Protein Serine-Threonine Kinases