title: FADD null mouse embryonic fibroblasts undergo apoptosis after photosensitization with the silicon phthalocyanine Pc 4.
abstract: Oxidative stress, such as photodynamic therapy with the silicon phthalocyanine Pc 4 (Pc 4-PDT), can induce apoptosis and tumor necrosis factor alpha (TNF) production. TNF receptors, as well as other death receptors, have been implicated in stress-induced apoptosis. To assess directly the role of FADD, a death receptor-associated protein, in induction of apoptosis post-Pc 4-PDT, embryonic fibroblasts from FADD knock out (k/o) and wild-type (wt) mice were used. Pc 4-PDT induced casp-3 activation and apoptosis in both cell types. In the presence of zVAD, a pancaspase inhibitor, Pc 4-PDT-induced apoptosis was abrogated in both cell lines. Fumonisin B1 (FB), an inhibitor of ceramide synthase, had no effect on apoptosis after Pc 4-PDT in either cell line. Similar to Pc 4-PDT, exogenous C6-ceramide bypassed FADD deficiency and induced zVAD-sensitive apoptosis. In contrast to Pc 4 photosensitization, TNF did not induce either apoptosis or ceramide accumulation in FADD k/o cells. In the absence of FADD deficiency, TNF-induced apoptosis was zVAD-sensitive and FB-insensitive. Induced ceramide levels remained elevated after cotreatment with TNF and zVAD in FADD wt cells. Taken together, these data provide genetic evidence for a lack of FADD requirement in Pc 4-PDT- or C6-ceramide-induced apoptosis. FB-sensitive ceramide production accompanies, but does not suffice, for apoptosis after Pc 4 photosensitization or TNF.
authors.affiliation: Faculty of Science, University of Zagreb, Croatia.
authors.forename: B
authors.initials: B
authors.lastname: Nagy
authors.forename: W C
authors.initials: WC
authors.lastname: Yeh
authors.forename: T W
authors.initials: TW
authors.lastname: Mak
authors.forename: S M
authors.initials: SM
authors.lastname: Chiu
authors.forename: D
authors.initials: D
authors.lastname: Separovic
mesh_terms: D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D017209:Apoptosis; D002264:Carboxylic Acids / Q000494:pharmacology; D002352:Carrier Proteins / Q000235:genetics* / Q000502:physiology*; D053148:Caspase 3; D020169:Caspases / Q000378:metabolism; D002518:Ceramides / Q000378:metabolism; D003513:Cycloheximide / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004307:Dose-Response Relationship, Radiation; D004789:Enzyme Activation; D053200:Fas-Associated Death Domain Protein; D005347:Fibroblasts / Q000473:pathology*; D037341:Fumonisins; D020287:In Situ Nick-End Labeling; D007211:Indoles / Q000494:pharmacology*; D008027:Light; D051379:Mice; D018345:Mice, Knockout; D008954:Models, Biological; D017646:Organosilicon Compounds / Q000494:pharmacology*; D018384:Oxidative Stress; D010088:Oxidoreductases / Q000037:antagonists & inhibitors; D010100:Oxygen / Q000378:metabolism; D017319:Photosensitizing Agents / Q000494:pharmacology*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D012821:Silanes; D013997:Time Factors; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D002264:Carboxylic Acids; D002352:Carrier Proteins; D002518:Ceramides; C505534:Fadd protein, mouse; D053200:Fas-Associated Death Domain Protein; D037341:Fumonisins; D007211:Indoles; D017646:Organosilicon Compounds; D017319:Photosensitizing Agents; D011500:Protein Synthesis Inhibitors; D012821:Silanes; D014409:Tumor Necrosis Factor-alpha; C082854:silicon phthalocyanine; C056933:fumonisin B1; C052464:bis(tri-n-hexylsiloxy)(2,3-naphthalocyaninato)silicon; D003513:Cycloheximide; D010088:Oxidoreductases; C108138:dihydroceramide desaturase; C505409:Casp3 protein, mouse; D053148:Caspase 3; D020169:Caspases; D010100:Oxygen