Calcium-dependent oxidation of thioredoxin during cellular growth initiation.
The fraction of cell thiol proteins in the oxidized disulfide form were quantified during mitogen-induced HaCaT keratinocyte growth initiation. Oxidized thioredoxin increased from 11 +/- 1.2% in resting cells to 80 and 61% 2 min after addition of bradykinin or EGF. Thioredoxin oxidation was transient returning toward normal values by 20 min. The disulfide forms of other cellular proteins rose in parallel with thioredoxin oxidation. The oxidation of thioredoxin depended on a rise in cytosolic calcium. It was prevented by preloading cells with BAPTA, a Ca(2+) chelator and induced by addition of Ca(2+)-ionophore A23187 or of thapsigargin. In cell extracts, thioredoxin reductase was inhibited by micromolar calcium. The rise in cytosolic Ca(2+) led to a concomitant burst of H(2)O(2) formation. The oxidizing intracellular milieu suggests that redox regulation actively participates in the growth initiation cascade. The role of peroxiredoxins and ASK 1 cascade activation are discussed in this context.
Gitler
Carlos
C
Department of Biological Chemistry, Weizmann Institute of Science, Rehovot, 76100, Israel. bmgitler@wicc.weizmann.ac.il
Zarmi
Batia
B
Kalef
Edna
E
Meller
Ruth
R
Zor
Uriel
U
Goldman
Rachel
R
D001920:Bradykinin / Q000494:pharmacology; D002118:Calcium / Q000378:metabolism* / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D002460:Cell Line; D002614:Chelating Agents / Q000494:pharmacology; D003600:Cytosol / Q000378:metabolism; D004220:Disulfides / Q000032:analysis / Q000378:metabolism; D004815:Epidermal Growth Factor / Q000494:pharmacology; D019803:Glutathione Disulfide / Q000737:chemistry; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism; D007476:Ionophores / Q000494:pharmacology; D015603:Keratinocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008934:Mitogens / Q000494:pharmacology; D010084:Oxidation-Reduction; D013347:Subcellular Fractions / Q000737:chemistry / Q000378:metabolism; D013438:Sulfhydryl Compounds / Q000378:metabolism; D013880:Thioredoxin-Disulfide Reductase / Q000037:antagonists & inhibitors / Q000378:metabolism; D013879:Thioredoxins / Q000378:metabolism*
D002614:Chelating Agents; D004220:Disulfides; D007476:Ionophores; D008934:Mitogens; D013438:Sulfhydryl Compounds; D013879:Thioredoxins; D004815:Epidermal Growth Factor; D006861:Hydrogen Peroxide; D013880:Thioredoxin-Disulfide Reductase; D001920:Bradykinin; D002118:Calcium; D019803:Glutathione Disulfide