title: Redox-sensing release of human thioredoxin from T lymphocytes with negative feedback loops.
abstract: Thioredoxin (TRX) is released from various types of mammalian cells despite no typical secretory signal sequence. We show here that a redox-active site in TRX is essential for its release from T lymphocytes in response to H2O2 and extracellular TRX regulates its own H2O2-induced release. Human T cell leukemia virus type I-transformed T lymphocytes constitutively release a large amount of TRX. The level of TRX release is augmented upon the addition of H2O2, but suppressed upon the addition of N-acetylcysteine. In the culture supernatant of a Jurkat transfectant expressing the tagged TRX-wild type (WT), the tagged TRX protein is rapidly released at 1 h and kept at a constant level until 6 h after the addition of H2O2. In contrast, another type of transfectant expressing the tagged TRX mutant (C32S/C35S; CS) fails to release the protein. H2O2-induced release of TRX from the transfectant is inhibited by the presence of rTRX-WT in a dose-dependent manner. Preincubation of the transfectant with rTRX-WT for 1 h at 37 degrees C, but not 0 degrees C, results in a significant suppression of the TRX release, reactive oxygen species, and caspase-3 activity induced by H2O2, respectively. Confocal microscopy and Western blot analysis show that extracellular rTRX-WT added to the culture does not obviously enter T lymphocytes until 24 h. These results collectively suggest that the oxidative stress-induced TRX release from T lymphocytes depends on a redox-sensitive event and may be regulated by negative feedback loops using reactive oxygen species-mediated signal transductions.
authors.affiliation: Department of Biological Responses, Institute for Virus Research, Kyoto University, Kyoto, Japan.
authors.forename: Norihiko
authors.initials: N
authors.lastname: Kondo
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Ishii
authors.forename: Yong-Won
authors.initials: YW
authors.lastname: Kwon
authors.forename: Masaki
authors.initials: M
authors.lastname: Tanito
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Horita
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Nishinaka
authors.forename: Hajime
authors.initials: H
authors.lastname: Nakamura
authors.forename: Junji
authors.initials: J
authors.lastname: Yodoi
mesh_terms: D017209:Apoptosis / Q000235:genetics / Q000502:physiology; D001665:Binding Sites / Q000235:genetics / Q000502:physiology; D002461:Cell Line, Transformed; D045604:Extracellular Fluid / Q000378:metabolism / Q000502:physiology; D025461:Feedback, Physiological / Q000235:genetics / Q000502:physiology*; D015368:Human T-lymphotropic virus 1 / Q000502:physiology; D006801:Humans; D006861:Hydrogen Peroxide / Q000037:antagonists & inhibitors / Q000494:pharmacology; D019169:Jurkat Cells; D010084:Oxidation-Reduction; D018384:Oxidative Stress / Q000235:genetics / Q000502:physiology; D011994:Recombinant Proteins / Q000494:pharmacology; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology; D013601:T-Lymphocytes / Q000187:drug effects / Q000378:metabolism*; D013879:Thioredoxins / Q000235:genetics / Q000378:metabolism*; D014162:Transfection
chemical_list: D011994:Recombinant Proteins; D013879:Thioredoxins; D006861:Hydrogen Peroxide