Induction of ERK1/2 and histone H3 phosphorylation within the outer stripe of the outer medulla of the Eker rat by 2,3,5-tris-(glutathion-S-yl)hydroquinone.
2,3,5-tris-(glutathion-S-yl)-hydroquinone (TGHQ), a metabolite of hydroquinone (HQ), generates reactive oxygen species (ROS) in cultured renal epithelial cells and binds to tissue macromolecules within the rat kidney. The potential mechanisms by which TGHQ induces nephrotoxicity and nephrocarcinogenesis have been examined in cell culture models, but less is known concerning the molecular mechanisms of TGHQ-induced nephrotoxicity in vivo. In LLC-PK1 cells, TGHQ induces phosphorylation of both mitogen-activated protein kinase and histone H3, which likely promotes inappropriate chromatin condensation and mitotic catastrophe. Using the Eker (Tsc-2 mutant) rat as a model, we show by immunohistochemistry that TGHQ (7.5 micromol/kg) selectively induces ERK1/2 phosphorylation within the outer stripe of the outer medulla (OSOM) of the kidney. ERK1/2 phosphorylation is time-dependant, occurring as early as 1 h following treatment, and reaching maximal levels by 4 h. Subsequently, ERK1/2 phosphorylation returns to baseline levels by 24 h post treatment. ERK1/2 phosphorylation was confirmed by western blot analysis of OSOM tissue. Increases in histone H3 phosphorylation occurred subsequent to ERK1/2 phosphorylation (8 h), and reached a peak by 24 h, coincident with histological evidence of tissue necrosis. In contrast to studies in cell culture, neither JNK/SAPK nor p38 MAPK phosphorylation were significantly altered after TGHQ administration in vivo, as evidenced by western blot and immunohistochemical analyses. These data indicate that activation of the ERK1/2 pathway precedes overt cytotoxicity and that the signaling pathways activated by TGHQ in vivo and in vitro differ.
Dong
Jing
J
Department of Pharmacology and Toxicology, College of Pharmacy, The University of Arizona Health Sciences Center, Tucson, Arizona 85721, USA.
Everitt
Jeffrey I
JI
Lau
Serrine S
SS
Monks
Terrence J
TJ
D000818:Animals; D015153:Blotting, Western; D004790:Enzyme Induction / Q000187:drug effects; D005978:Glutathione / Q000031:analogs & derivatives* / Q000633:toxicity*; D006657:Histones / Q000378:metabolism*; D006873:Hydroquinones / Q000633:toxicity*; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D007202:Indicators and Reagents; D048031:JNK Mitogen-Activated Protein Kinases / Q000378:metabolism; D007674:Kidney Diseases / Q000139:chemically induced / Q000473:pathology; D007679:Kidney Medulla / Q000378:metabolism*; D048670:MAP Kinase Kinase 4; D008297:Male; D020929:Mitogen-Activated Protein Kinase Kinases / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000096:biosynthesis*; D010766:Phosphorylation; D051381:Rats; D048051:p38 Mitogen-Activated Protein Kinases / Q000378:metabolism
D006657:Histones; D006873:Hydroquinones; D007202:Indicators and Reagents; C078765:2,3,5-(triglutathion-S-yl)hydroquinone; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases; D048670:MAP Kinase Kinase 4; D020929:Mitogen-Activated Protein Kinase Kinases; D005978:Glutathione