Transient Proteotoxicity of Bacterial Virulence Factor Pyocyanin in Renal Tubular Epithelial Cells Induces ER-Related Vacuolation and Can Be Efficiently Modulated by Iron Chelators.
Persistent infections of biofilm forming bacteria, such as Pseudomonas aeruginosa, are common among human populations, due to the bacterial resistance to antibiotics and other adaptation strategies, including release of cytotoxic virulent factors such as pigment pyocyanin (PCN). Urinary tract infections harbor P. aeruginosa strains characterized by the highest PCN-producing capacity, yet no information is available on PCN cytotoxicity mechanism in kidney. We report here that renal tubular epithelial cell (RTEC) line NRK-52E responds to PCN treatments with paraptosis-like activity features. Specifically, PCN-treated cells experienced dilation of endoplasmic reticulum (ER) and an extensive development of ER-derived vacuoles after about 8 h. This process was accompanied with hyper-activation of proteotoxic stress-inducible transcription factors Nrf2, ATF6, and HSF-1. The cells could be rescued by withdrawal of PCN from the culture media before the vacuoles burst and cells die of non-programmed necrosis after about 24-30 h. The paraptosis-like activity was abrogated by co-treatment of the cells with metal-chelating antioxidants. A microscopic examination of cells co-treated with PCN and agents aiming at a variety of the cellular stress mediators and pathways have identified iron as a single most significant co-factor of the PCN cytotoxicity in the RTECs. Among biologically relevant metal ions, low micromolar Fe2+specifically mediated anaerobic oxidation of glutathione by PCN, but catechol derivatives and other strong iron complexing agents could inhibit the reaction. Our data suggest that iron chelation could be considered as a supplementary treatment in the PCN-positive infections.
Department of Biochemistry mossinev@missouri.edu.|Experiment Station Chemical Labs, University of Missouri, Columbia, Missouri 65211.
Valeri V
VV
Mossine
Experiment Station Chemical Labs, University of Missouri, Columbia, Missouri 65211.
James K
JK
Waters
Department of Molecular Microbiology and Immunology.|Department of Child Health, University of Missouri, Columbia, Missouri 65211.
Deborah L
DL
Chance
Department of Biochemistry.|Experiment Station Chemical Labs, University of Missouri, Columbia, Missouri 65211.|Department of Child Health, University of Missouri, Columbia, Missouri 65211.
Thomas P
TP
Mawhinney
D051702:Activating Transcription Factor 6 / Q000235:genetics / Q000378:metabolism; D000818:Animals; D002460:Cell Line; D049109:Cell Proliferation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004721:Endoplasmic Reticulum / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D004847:Epithelial Cells / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D005978:Glutathione / Q000378:metabolism; D000076249:Heat Shock Transcription Factors / Q000235:genetics / Q000378:metabolism; D007501:Iron / Q000378:metabolism*; D007502:Iron Chelating Agents / Q000494:pharmacology*; D007684:Kidney Tubules / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D051267:NF-E2-Related Factor 2 / Q000235:genetics / Q000378:metabolism; D009336:Necrosis; D018384:Oxidative Stress / Q000187:drug effects; D011550:Pseudomonas aeruginosa / Q000378:metabolism / Q000472:pathogenicity*; D011710:Pyocyanine / Q000138:chemical synthesis / Q000494:pharmacology*; D051381:Rats; D013997:Time Factors; D056811:Unfolded Protein Response / Q000187:drug effects; D014617:Vacuoles / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D014774:Virulence
C497111:ATF6 protein, human; D051702:Activating Transcription Factor 6; C000619706:HSF1 protein, human; D000076249:Heat Shock Transcription Factors; D007502:Iron Chelating Agents; D051267:NF-E2-Related Factor 2; C495635:NFE2L2 protein, human; D011710:Pyocyanine; D007501:Iron; D005978:Glutathione
Pyocyanin; endoplasmic reticulum stress.; glutathione; iron; proteotoxic stress response; renal tubular epithelial cells