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Redox amplification of apoptosis by caspase-dependent cleavage of glutaredoxin 1 and S-glutathionylation of Fas.

Anathy V, Aesif SW, Guala AS, Havermans M, Reynaert NL, Ho YS, Budd RC, Janssen-Heininger YM - J. Cell Biol. (2009)

Bottom Line: In this study, we demonstrate that stimulation with Fas ligand (FasL) induces S-glutathionylation of Fas at cysteine 294 independently of nicotinamide adenine dinucleotide phosphate reduced oxidase-induced ROS.As a result, death-inducing signaling complex formation is also increased, and subsequent activation of caspase-8 and -3 is augmented.These results define a novel redox-based mechanism to propagate Fas-dependent apoptosis.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, University of Vermont, Burlington, VT 05405, USA.

ABSTRACT
Reactive oxygen species (ROS) increase ligation of Fas (CD95), a receptor important for regulation of programmed cell death. Glutathionylation of reactive cysteines represents an oxidative modification that can be reversed by glutaredoxins (Grxs). The goal of this study was to determine whether Fas is redox regulated under physiological conditions. In this study, we demonstrate that stimulation with Fas ligand (FasL) induces S-glutathionylation of Fas at cysteine 294 independently of nicotinamide adenine dinucleotide phosphate reduced oxidase-induced ROS. Instead, Fas is S-glutathionylated after caspase-dependent degradation of Grx1, increasing subsequent caspase activation and apoptosis. Conversely, overexpression of Grx1 attenuates S-glutathionylation of Fas and partially protects against FasL-induced apoptosis. Redox-mediated Fas modification promotes its aggregation and recruitment into lipid rafts and enhances binding of FasL. As a result, death-inducing signaling complex formation is also increased, and subsequent activation of caspase-8 and -3 is augmented. These results define a novel redox-based mechanism to propagate Fas-dependent apoptosis.

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FasL induces caspase-dependent cleavage of Grx1 and increases PSSG as well as S-glutathionylation of Fas. (A) Immunoblot analysis of cleaved caspase-8 (p18) and -3 fragments (p17 and p19) in C10 cells treated with FasL + M2 as described in Fig. 1 in the presence or absence of 10 µM ZVAD-FMK. The bottom panel shows total cellular content of Grx1. Note that expression of the pro form of caspase-8 remains unchanged during the course of the experiment. (B) Evaluation of the interaction between Grx1 and caspase-8 or -3 in cells. C10 cells were exposed to FasL + M2 as described in Fig. 1 A, and Grx1 was immunoprecipitated (IP) at the indicated times for the evaluation of association with active caspase-8 or -3 fragments via Western blotting. The bottom panel represents a Grx1 immunoblot. Lanes on the right represent lysates from cells treated with FasL + M2 for 2 h but were subjected to IgG IP as a reagent control. All samples were run on the same gel, and the lanes were cut and reassembled for consistency. The bottom panels represent total content of proteins in whole cell lysates (WCL) that were used as the input for IP. Note that expression of the pro form of caspase-8 remains unchanged during the course of the experiment. Black line indicates that intervening lanes have been spliced out. (C) In vitro assessment of cleavage of Grx1 by caspase-8 or -3. 200 ng recombinant hGrx1 was incubated with 200 U active caspase-8 or -3. At the indicated times, samples were prepared for immunoblot analysis of hGrx1. Fragmented hGrx1 product is ∼8 kD in size. Incubation of heat-inactivated caspase-8 and -3 with hGrx1 for 4 h largely prevented the formation of cleaved fragment (0 h). (D) Increases in overall PSSG are a response to ligation of Fas and are caspase dependent. Cells were incubated as described in A. ZVAD-FMK or vehicle was added to cells 2 h before ligation of Fas as well as 2 h after ligation. Lysates were resolved by nonreducing SDS-PAGE. Antiglutathione antibody was used to detect PSSG on immunoblots. The bottom panel shows total Fas content. (E) Caspase-dependent S-glutathionylation of Fas. C10 cells were incubated with FasL + M2 for 0.5, 1, or 2 h in the presence or absence of ZVAD-FMK. Cell lysates were subjected to nonreducing IP (−DTT) using antiglutathione antibody to IP S-glutathionylated proteins (IP: PSSG) before detection of Fas via Western blotting. As a reagent control to reduce S-glutathionylated proteins before IP, samples were incubated with 50 mM DTT (+DTT). The bottom panel represents Fas content in cell lysates. (F) S-glutathionylation of Fas requires the presence of caspase-8. C10 cells were transfected with control (Ctr) siRNA or caspase-8 (C8)–specific siRNA and 48 h later were incubated with FasL + M2 for 2 or 4 h. The top lane shows assessment of S-glutathionylation of Fas via IP of S-glutathionylated proteins using antiglutathione antibody (IP: PSSG) under nonreducing conditions (−DTT) before detection of Fas via Western blotting. As a reagent control to reduce S-glutathionylated proteins before IP, samples were incubated with 50 mM DTT (+DTT). The bottom panels show total content of Fas, procaspase-8, cleaved caspase-8, cleaved caspase-3, and Grx1 in whole cell lysates. (G) Assessment of caspase-dependent degradation of Grx1 and S-glutathionylation of Fas in NIH 3T3 cells after ligation of Fas. Cells were treated with 500 ng/ml FasL + 1 µg/ml M2 for 1, 2, or 4 h in the presence or absence of ZVAD-FMK. S-glutathionylated proteins were immunoprecipitated as described in E before detection of Fas via Western blotting. The bottom panel represents Fas content, cleaved caspase-3, and Grx1 content in whole cell lysates.
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fig2: FasL induces caspase-dependent cleavage of Grx1 and increases PSSG as well as S-glutathionylation of Fas. (A) Immunoblot analysis of cleaved caspase-8 (p18) and -3 fragments (p17 and p19) in C10 cells treated with FasL + M2 as described in Fig. 1 in the presence or absence of 10 µM ZVAD-FMK. The bottom panel shows total cellular content of Grx1. Note that expression of the pro form of caspase-8 remains unchanged during the course of the experiment. (B) Evaluation of the interaction between Grx1 and caspase-8 or -3 in cells. C10 cells were exposed to FasL + M2 as described in Fig. 1 A, and Grx1 was immunoprecipitated (IP) at the indicated times for the evaluation of association with active caspase-8 or -3 fragments via Western blotting. The bottom panel represents a Grx1 immunoblot. Lanes on the right represent lysates from cells treated with FasL + M2 for 2 h but were subjected to IgG IP as a reagent control. All samples were run on the same gel, and the lanes were cut and reassembled for consistency. The bottom panels represent total content of proteins in whole cell lysates (WCL) that were used as the input for IP. Note that expression of the pro form of caspase-8 remains unchanged during the course of the experiment. Black line indicates that intervening lanes have been spliced out. (C) In vitro assessment of cleavage of Grx1 by caspase-8 or -3. 200 ng recombinant hGrx1 was incubated with 200 U active caspase-8 or -3. At the indicated times, samples were prepared for immunoblot analysis of hGrx1. Fragmented hGrx1 product is ∼8 kD in size. Incubation of heat-inactivated caspase-8 and -3 with hGrx1 for 4 h largely prevented the formation of cleaved fragment (0 h). (D) Increases in overall PSSG are a response to ligation of Fas and are caspase dependent. Cells were incubated as described in A. ZVAD-FMK or vehicle was added to cells 2 h before ligation of Fas as well as 2 h after ligation. Lysates were resolved by nonreducing SDS-PAGE. Antiglutathione antibody was used to detect PSSG on immunoblots. The bottom panel shows total Fas content. (E) Caspase-dependent S-glutathionylation of Fas. C10 cells were incubated with FasL + M2 for 0.5, 1, or 2 h in the presence or absence of ZVAD-FMK. Cell lysates were subjected to nonreducing IP (−DTT) using antiglutathione antibody to IP S-glutathionylated proteins (IP: PSSG) before detection of Fas via Western blotting. As a reagent control to reduce S-glutathionylated proteins before IP, samples were incubated with 50 mM DTT (+DTT). The bottom panel represents Fas content in cell lysates. (F) S-glutathionylation of Fas requires the presence of caspase-8. C10 cells were transfected with control (Ctr) siRNA or caspase-8 (C8)–specific siRNA and 48 h later were incubated with FasL + M2 for 2 or 4 h. The top lane shows assessment of S-glutathionylation of Fas via IP of S-glutathionylated proteins using antiglutathione antibody (IP: PSSG) under nonreducing conditions (−DTT) before detection of Fas via Western blotting. As a reagent control to reduce S-glutathionylated proteins before IP, samples were incubated with 50 mM DTT (+DTT). The bottom panels show total content of Fas, procaspase-8, cleaved caspase-8, cleaved caspase-3, and Grx1 in whole cell lysates. (G) Assessment of caspase-dependent degradation of Grx1 and S-glutathionylation of Fas in NIH 3T3 cells after ligation of Fas. Cells were treated with 500 ng/ml FasL + 1 µg/ml M2 for 1, 2, or 4 h in the presence or absence of ZVAD-FMK. S-glutathionylated proteins were immunoprecipitated as described in E before detection of Fas via Western blotting. The bottom panel represents Fas content, cleaved caspase-3, and Grx1 content in whole cell lysates.

Mentions: Engagement of Fas causes a rapid activation of caspase-8 and -3 (Hengartner, 2000). Sequence analysis of murine Grx1 suggested that amino acids 43–46 (EFVD) and 56–59 (AIQD) may be putative cleavage sites of caspase-8 and -3, both of which have predicted affinity toward glutamic and aspartic acid residues (Fig. S1, available at http://www.jcb.org/cgi/content/full/jcb.200807019/DC1; Earnshaw et al., 1999). This raised the possibility that upon ligation of Fas, Grx1 was degraded in a caspase-dependent fashion. Indeed, pretreatment of cells with a generic caspase inhibitor, ZVAD-FMK, effectively blocked FasL-induced cleavage of caspase-8 and -3 and completely prevented FasL-induced degradation of Grx1 (Fig. 2 A). Immunoprecipitation (IP) of Grx1 followed by immunoblot analysis of cleaved caspase-8 and -3 demonstrated an association between active caspases and Grx1 in cells after ligation of Fas, whereas in control cells, these associations were not observed (Fig. 2 B). Incubation of recombinant Grx1 with active caspase-8 or -3 in vitro led to the formation of a fragment of ∼8 kD, which was more apparent in response to caspase-3 as compared with caspase-8 (Fig. 2 C). Consistent with the protection against Grx1 degradation (Fig. 2 A), pretreatment of cells with ZVAD-FMK prevented the formation of detectable levels of PSSG after FasL stimulation (Fig. 2 D). Based on our observations that proteins that were S-glutathionylated upon stimulation of cells with FasL comigrated with Fas, we speculated that Fas itself could be a target for S-glutathionylation. Lysates from FasL-treated cells were immunoprecipitated using an antiglutathione antibody followed by detection of Fas by immunoblotting. After FasL stimulation, Fas-SSG (S-glutathionylated Fas) was detectable as early as 1 h after Fas ligation with further increases apparent after 2 h (Fig. 2 E). To confirm the specificity of the immunoreactivity, the S-glutathionylated proteins were reduced with 50 mM DTT. As expected, samples treated with DTT (Fig. 2 E, +DTT) before IP showed no immunoreactivity for Fas, demonstrating the PSSG-specific IP of Fas in response to stimulation with FasL (Fig. 2 E). Lastly, pretreatment of cells with ZVAD-FMK before FasL resulted in no detectable Fas-SSG (Fig. 2 E), which is consistent with the absence of PSSG in cells exposed to ZVAD-FMK within this time frame (Fig. 2 D). To corroborate the requirement of caspases in the degradation of Grx1 and accumulation of Fas-SSG, we treated lung epithelial cells with control or caspase-8–specific siRNA. Results shown in Fig. 2 F demonstrate that FasL-induced degradation of Grx1 and accumulation of Fas-SSG were largely absent in cells with markedly lowered caspase-8 content. Caspase-dependent degradation of Grx1 and accumulation of Fas-SSG were also readily apparent in NIH 3T3 cells (Fig. 2 G), demonstrating that these redox changes occur in cell types other than lung epithelial cells. Lastly, incubation of cells with staurosporine did not cause S-glutathionylation of Fas nor marked degradation of Grx1 despite causing robust cleavage of caspase-3 (Fig. S1 B), suggesting that activation of caspases by other agonists is insufficient to cause the formation of Fas-SSG. In aggregate, these findings demonstrate that after stimulation of cells with FasL, caspase-dependent degradation of Grx1 occurs in association with increases in Fas-SSG. Our data also suggest that caspase activation is necessary but may not be sufficient for degradation of Grx1.


Redox amplification of apoptosis by caspase-dependent cleavage of glutaredoxin 1 and S-glutathionylation of Fas.

Anathy V, Aesif SW, Guala AS, Havermans M, Reynaert NL, Ho YS, Budd RC, Janssen-Heininger YM - J. Cell Biol. (2009)

FasL induces caspase-dependent cleavage of Grx1 and increases PSSG as well as S-glutathionylation of Fas. (A) Immunoblot analysis of cleaved caspase-8 (p18) and -3 fragments (p17 and p19) in C10 cells treated with FasL + M2 as described in Fig. 1 in the presence or absence of 10 µM ZVAD-FMK. The bottom panel shows total cellular content of Grx1. Note that expression of the pro form of caspase-8 remains unchanged during the course of the experiment. (B) Evaluation of the interaction between Grx1 and caspase-8 or -3 in cells. C10 cells were exposed to FasL + M2 as described in Fig. 1 A, and Grx1 was immunoprecipitated (IP) at the indicated times for the evaluation of association with active caspase-8 or -3 fragments via Western blotting. The bottom panel represents a Grx1 immunoblot. Lanes on the right represent lysates from cells treated with FasL + M2 for 2 h but were subjected to IgG IP as a reagent control. All samples were run on the same gel, and the lanes were cut and reassembled for consistency. The bottom panels represent total content of proteins in whole cell lysates (WCL) that were used as the input for IP. Note that expression of the pro form of caspase-8 remains unchanged during the course of the experiment. Black line indicates that intervening lanes have been spliced out. (C) In vitro assessment of cleavage of Grx1 by caspase-8 or -3. 200 ng recombinant hGrx1 was incubated with 200 U active caspase-8 or -3. At the indicated times, samples were prepared for immunoblot analysis of hGrx1. Fragmented hGrx1 product is ∼8 kD in size. Incubation of heat-inactivated caspase-8 and -3 with hGrx1 for 4 h largely prevented the formation of cleaved fragment (0 h). (D) Increases in overall PSSG are a response to ligation of Fas and are caspase dependent. Cells were incubated as described in A. ZVAD-FMK or vehicle was added to cells 2 h before ligation of Fas as well as 2 h after ligation. Lysates were resolved by nonreducing SDS-PAGE. Antiglutathione antibody was used to detect PSSG on immunoblots. The bottom panel shows total Fas content. (E) Caspase-dependent S-glutathionylation of Fas. C10 cells were incubated with FasL + M2 for 0.5, 1, or 2 h in the presence or absence of ZVAD-FMK. Cell lysates were subjected to nonreducing IP (−DTT) using antiglutathione antibody to IP S-glutathionylated proteins (IP: PSSG) before detection of Fas via Western blotting. As a reagent control to reduce S-glutathionylated proteins before IP, samples were incubated with 50 mM DTT (+DTT). The bottom panel represents Fas content in cell lysates. (F) S-glutathionylation of Fas requires the presence of caspase-8. C10 cells were transfected with control (Ctr) siRNA or caspase-8 (C8)–specific siRNA and 48 h later were incubated with FasL + M2 for 2 or 4 h. The top lane shows assessment of S-glutathionylation of Fas via IP of S-glutathionylated proteins using antiglutathione antibody (IP: PSSG) under nonreducing conditions (−DTT) before detection of Fas via Western blotting. As a reagent control to reduce S-glutathionylated proteins before IP, samples were incubated with 50 mM DTT (+DTT). The bottom panels show total content of Fas, procaspase-8, cleaved caspase-8, cleaved caspase-3, and Grx1 in whole cell lysates. (G) Assessment of caspase-dependent degradation of Grx1 and S-glutathionylation of Fas in NIH 3T3 cells after ligation of Fas. Cells were treated with 500 ng/ml FasL + 1 µg/ml M2 for 1, 2, or 4 h in the presence or absence of ZVAD-FMK. S-glutathionylated proteins were immunoprecipitated as described in E before detection of Fas via Western blotting. The bottom panel represents Fas content, cleaved caspase-3, and Grx1 content in whole cell lysates.
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fig2: FasL induces caspase-dependent cleavage of Grx1 and increases PSSG as well as S-glutathionylation of Fas. (A) Immunoblot analysis of cleaved caspase-8 (p18) and -3 fragments (p17 and p19) in C10 cells treated with FasL + M2 as described in Fig. 1 in the presence or absence of 10 µM ZVAD-FMK. The bottom panel shows total cellular content of Grx1. Note that expression of the pro form of caspase-8 remains unchanged during the course of the experiment. (B) Evaluation of the interaction between Grx1 and caspase-8 or -3 in cells. C10 cells were exposed to FasL + M2 as described in Fig. 1 A, and Grx1 was immunoprecipitated (IP) at the indicated times for the evaluation of association with active caspase-8 or -3 fragments via Western blotting. The bottom panel represents a Grx1 immunoblot. Lanes on the right represent lysates from cells treated with FasL + M2 for 2 h but were subjected to IgG IP as a reagent control. All samples were run on the same gel, and the lanes were cut and reassembled for consistency. The bottom panels represent total content of proteins in whole cell lysates (WCL) that were used as the input for IP. Note that expression of the pro form of caspase-8 remains unchanged during the course of the experiment. Black line indicates that intervening lanes have been spliced out. (C) In vitro assessment of cleavage of Grx1 by caspase-8 or -3. 200 ng recombinant hGrx1 was incubated with 200 U active caspase-8 or -3. At the indicated times, samples were prepared for immunoblot analysis of hGrx1. Fragmented hGrx1 product is ∼8 kD in size. Incubation of heat-inactivated caspase-8 and -3 with hGrx1 for 4 h largely prevented the formation of cleaved fragment (0 h). (D) Increases in overall PSSG are a response to ligation of Fas and are caspase dependent. Cells were incubated as described in A. ZVAD-FMK or vehicle was added to cells 2 h before ligation of Fas as well as 2 h after ligation. Lysates were resolved by nonreducing SDS-PAGE. Antiglutathione antibody was used to detect PSSG on immunoblots. The bottom panel shows total Fas content. (E) Caspase-dependent S-glutathionylation of Fas. C10 cells were incubated with FasL + M2 for 0.5, 1, or 2 h in the presence or absence of ZVAD-FMK. Cell lysates were subjected to nonreducing IP (−DTT) using antiglutathione antibody to IP S-glutathionylated proteins (IP: PSSG) before detection of Fas via Western blotting. As a reagent control to reduce S-glutathionylated proteins before IP, samples were incubated with 50 mM DTT (+DTT). The bottom panel represents Fas content in cell lysates. (F) S-glutathionylation of Fas requires the presence of caspase-8. C10 cells were transfected with control (Ctr) siRNA or caspase-8 (C8)–specific siRNA and 48 h later were incubated with FasL + M2 for 2 or 4 h. The top lane shows assessment of S-glutathionylation of Fas via IP of S-glutathionylated proteins using antiglutathione antibody (IP: PSSG) under nonreducing conditions (−DTT) before detection of Fas via Western blotting. As a reagent control to reduce S-glutathionylated proteins before IP, samples were incubated with 50 mM DTT (+DTT). The bottom panels show total content of Fas, procaspase-8, cleaved caspase-8, cleaved caspase-3, and Grx1 in whole cell lysates. (G) Assessment of caspase-dependent degradation of Grx1 and S-glutathionylation of Fas in NIH 3T3 cells after ligation of Fas. Cells were treated with 500 ng/ml FasL + 1 µg/ml M2 for 1, 2, or 4 h in the presence or absence of ZVAD-FMK. S-glutathionylated proteins were immunoprecipitated as described in E before detection of Fas via Western blotting. The bottom panel represents Fas content, cleaved caspase-3, and Grx1 content in whole cell lysates.
Mentions: Engagement of Fas causes a rapid activation of caspase-8 and -3 (Hengartner, 2000). Sequence analysis of murine Grx1 suggested that amino acids 43–46 (EFVD) and 56–59 (AIQD) may be putative cleavage sites of caspase-8 and -3, both of which have predicted affinity toward glutamic and aspartic acid residues (Fig. S1, available at http://www.jcb.org/cgi/content/full/jcb.200807019/DC1; Earnshaw et al., 1999). This raised the possibility that upon ligation of Fas, Grx1 was degraded in a caspase-dependent fashion. Indeed, pretreatment of cells with a generic caspase inhibitor, ZVAD-FMK, effectively blocked FasL-induced cleavage of caspase-8 and -3 and completely prevented FasL-induced degradation of Grx1 (Fig. 2 A). Immunoprecipitation (IP) of Grx1 followed by immunoblot analysis of cleaved caspase-8 and -3 demonstrated an association between active caspases and Grx1 in cells after ligation of Fas, whereas in control cells, these associations were not observed (Fig. 2 B). Incubation of recombinant Grx1 with active caspase-8 or -3 in vitro led to the formation of a fragment of ∼8 kD, which was more apparent in response to caspase-3 as compared with caspase-8 (Fig. 2 C). Consistent with the protection against Grx1 degradation (Fig. 2 A), pretreatment of cells with ZVAD-FMK prevented the formation of detectable levels of PSSG after FasL stimulation (Fig. 2 D). Based on our observations that proteins that were S-glutathionylated upon stimulation of cells with FasL comigrated with Fas, we speculated that Fas itself could be a target for S-glutathionylation. Lysates from FasL-treated cells were immunoprecipitated using an antiglutathione antibody followed by detection of Fas by immunoblotting. After FasL stimulation, Fas-SSG (S-glutathionylated Fas) was detectable as early as 1 h after Fas ligation with further increases apparent after 2 h (Fig. 2 E). To confirm the specificity of the immunoreactivity, the S-glutathionylated proteins were reduced with 50 mM DTT. As expected, samples treated with DTT (Fig. 2 E, +DTT) before IP showed no immunoreactivity for Fas, demonstrating the PSSG-specific IP of Fas in response to stimulation with FasL (Fig. 2 E). Lastly, pretreatment of cells with ZVAD-FMK before FasL resulted in no detectable Fas-SSG (Fig. 2 E), which is consistent with the absence of PSSG in cells exposed to ZVAD-FMK within this time frame (Fig. 2 D). To corroborate the requirement of caspases in the degradation of Grx1 and accumulation of Fas-SSG, we treated lung epithelial cells with control or caspase-8–specific siRNA. Results shown in Fig. 2 F demonstrate that FasL-induced degradation of Grx1 and accumulation of Fas-SSG were largely absent in cells with markedly lowered caspase-8 content. Caspase-dependent degradation of Grx1 and accumulation of Fas-SSG were also readily apparent in NIH 3T3 cells (Fig. 2 G), demonstrating that these redox changes occur in cell types other than lung epithelial cells. Lastly, incubation of cells with staurosporine did not cause S-glutathionylation of Fas nor marked degradation of Grx1 despite causing robust cleavage of caspase-3 (Fig. S1 B), suggesting that activation of caspases by other agonists is insufficient to cause the formation of Fas-SSG. In aggregate, these findings demonstrate that after stimulation of cells with FasL, caspase-dependent degradation of Grx1 occurs in association with increases in Fas-SSG. Our data also suggest that caspase activation is necessary but may not be sufficient for degradation of Grx1.

Bottom Line: In this study, we demonstrate that stimulation with Fas ligand (FasL) induces S-glutathionylation of Fas at cysteine 294 independently of nicotinamide adenine dinucleotide phosphate reduced oxidase-induced ROS.As a result, death-inducing signaling complex formation is also increased, and subsequent activation of caspase-8 and -3 is augmented.These results define a novel redox-based mechanism to propagate Fas-dependent apoptosis.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology, University of Vermont, Burlington, VT 05405, USA.

ABSTRACT
Reactive oxygen species (ROS) increase ligation of Fas (CD95), a receptor important for regulation of programmed cell death. Glutathionylation of reactive cysteines represents an oxidative modification that can be reversed by glutaredoxins (Grxs). The goal of this study was to determine whether Fas is redox regulated under physiological conditions. In this study, we demonstrate that stimulation with Fas ligand (FasL) induces S-glutathionylation of Fas at cysteine 294 independently of nicotinamide adenine dinucleotide phosphate reduced oxidase-induced ROS. Instead, Fas is S-glutathionylated after caspase-dependent degradation of Grx1, increasing subsequent caspase activation and apoptosis. Conversely, overexpression of Grx1 attenuates S-glutathionylation of Fas and partially protects against FasL-induced apoptosis. Redox-mediated Fas modification promotes its aggregation and recruitment into lipid rafts and enhances binding of FasL. As a result, death-inducing signaling complex formation is also increased, and subsequent activation of caspase-8 and -3 is augmented. These results define a novel redox-based mechanism to propagate Fas-dependent apoptosis.

Show MeSH
Related in: MedlinePlus