Soluble receptor (DcR3) and cellular inhibitor of apoptosis-2 (cIAP-2) protect human cytotrophoblast cells against LIGHT-mediated apoptosis.
LIGHT (tumor necrosis factor superfamily 14) is among the powerful apoptosis-inducing cytokines synthesized in human placentas. Here, we investigated mechanisms protecting cytotrophoblast (CTB) cells from LIGHT-mediated apoptosis. Viability assays and caspase-3 immunoblots using recombinant LIGHT were done to establish that CTB cells purified from term placentas resist LIGHT-induced apoptosis. Although the cells were also resistant to killing by another placental cytokine, interferon-gamma (IFN-gamma), a combination of the two induced apoptosis. Killing was prevented by DcR3-Fc fragment but not control human-Fc fragment, showing that apoptosis occurs via the LIGHT pathway and that soluble receptors provide protection. Next, two cellular inhibitors of apoptosis expressed in CTB cells, cellular inhibitor of apoptosis (cIAP)-1 and cIAP-2, were investigated for protection. Cellular IAP-1 was unchanged after stimulation with LIGHT whereas cIAP-2 mRNA and protein were elevated. The increase was abrogated by treating CTB cells with LIGHT + IFN-gamma, implying a central role for cIAP-2 in preventing LIGHT-mediated apoptosis and an ability of IFN-gamma to overcome cIAP-2 protection. Definitive evidence was provided in experiments that showed that cIAP-2 anti-sense morpholinos permit LIGHT to induce apoptosis in HT-29 cells. In summary, the data are consistent with the postulate that placental CTB cells are protected from LIGHT-mediated apoptosis by both soluble receptor, DcR3, and cIAP-2.
Gill
Ryan M
RM
Department of Pathology and Laboratory Medicine, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, KS 66160-7400, USA.
Hunt
Joan S
JS
D017209:Apoptosis / Q000187:drug effects / Q000502:physiology*; D020169:Caspases / Q000378:metabolism; D002470:Cell Survival; D004357:Drug Synergism; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D019073:HT29 Cells; D006801:Humans; D007371:Interferon-gamma / Q000494:pharmacology; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D008954:Models, Biological; D016376:Oligonucleotides, Antisense / Q000494:pharmacology; D010446:Peptide Fragments / Q000378:metabolism; D010920:Placenta / Q000166:cytology; D011247:Pregnancy; D011506:Proteins / Q000032:analysis / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis / Q000378:metabolism; D018124:Receptors, Tumor Necrosis Factor / Q000737:chemistry / Q000378:metabolism*; D011994:Recombinant Proteins / Q000378:metabolism / Q000494:pharmacology; D012995:Solubility; D014327:Trophoblasts / Q000166:cytology / Q000378:metabolism*; D053326:Tumor Necrosis Factor Ligand Superfamily Member 14; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology
D008565:Membrane Proteins; D016376:Oligonucleotides, Antisense; D010446:Peptide Fragments; D011506:Proteins; D012333:RNA, Messenger; D018124:Receptors, Tumor Necrosis Factor; D011994:Recombinant Proteins; C505914:TNFSF14 protein, human; D053326:Tumor Necrosis Factor Ligand Superfamily Member 14; D014409:Tumor Necrosis Factor-alpha; D007371:Interferon-gamma; D020169:Caspases