Hydrogen peroxide inhibition of nuclear protein import is mediated by the mitogen-activated protein kinase, ERK2.
H(2)O(2) alters gene expression in many cell types. Alterations in nuclear import of transcription factors or similar key proteins may be responsible for these changes. To investigate this possibility, a cytosolic nuclear import cocktail was treated with varying ¿H(2)O(2) and used in import assays. H(2)O(2) caused a dose- and time-dependent inhibition of import at concentrations as low as 100 microM. Catalase reversed this effect. H(2)O(2) treatment of permeablized cells did not affect import, suggesting that H(2)O(2) was acting on a cytosolic factor. Treatment of import cocktail with two different free radical generating systems had no effect, but treatment of permeablized cells inhibited import, suggesting H(2)O(2) works via a distinct process from hydroxyl or superoxide radicals. Pretreatment of import cocktail with genistein reversed the effect of H(2)O(2) on import. Western blotting revealed that H(2)O(2) activated ERK2. The specific MEK1/2 inhibitor, PD98059, completely blocked the effects of H(2)O(2) on import. Activated ERK2 mimicked H(2)O(2)'s effect on import. Immunocytochemistry revealed that H(2)O(2) treatment of whole cells increased cytosolic Ran/TC4 levels, an effect reversible by catalase or PD98059. These data demonstrate that H(2)O(2) inhibits nuclear protein import and that this effect is mediated by mitogen-activated protein (MAP) kinase activation, possibly by altering Ran/TC4 function.
Czubryt
M P
MP
Cell Biology Laboratory, Division of Stroke and Vascular Disease, St. Boniface General Hospital Research Centre and the Department of Physiology, University of Manitoba, Winnipeg, Manitoba, Canada R2H 2A6.
Austria
J A
JA
Pierce
G N
GN
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D001896:Boron Compounds / Q000378:metabolism; D002478:Cells, Cultured; D004789:Enzyme Activation; D005456:Fluorescent Dyes / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism* / Q000494:pharmacology; D008297:Male; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D009131:Muscle, Smooth, Vascular / Q000166:cytology; D009687:Nuclear Proteins / Q000378:metabolism*; D010084:Oxidation-Reduction; D011817:Rabbits; D051381:Rats; D017207:Rats, Sprague-Dawley; D012710:Serum Albumin, Bovine / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism; D020931:ran GTP-Binding Protein / Q000378:metabolism
C095489:4,4-difluoro-4-bora-3a,4a-diaza-s-indacene; D001896:Boron Compounds; D005456:Fluorescent Dyes; D009687:Nuclear Proteins; D013481:Superoxides; D012710:Serum Albumin, Bovine; D006861:Hydrogen Peroxide; D019950:Mitogen-Activated Protein Kinase 1; D020931:ran GTP-Binding Protein