Programmed necrotic cell death induced by complement involves a Bid-dependent pathway.
The membrane attack complex (MAC) of the complement system induces a necrotic-type cell death. Earlier findings suggested that Bcl-2 protects cells from MAC-induced necrosis. Here we examined the involvement of Bid, a proapoptotic protein, in MAC-induced cytotoxicity. Bid knockout (Bid-/-) mouse embryonic fibroblasts (MEF) and primary fibroblasts were damaged by complement but to a significantly lower extent than wild-type (WT) fibroblasts. Bid silencing with small interfering RNA duplexes led to elevated resistance of mouse fibroblasts, human K562, and Jurkat cells to lysis by complement. Bid-/- MEF were also resistant to toxic doses of streptolysin O, melittin, and A23187. Analysis of complement protein deposition on fibroblasts demonstrated that less complement C3 and C9 bound to Bid-/- than to WT cells, even though expression of the membrane complement inhibitors Crry and CD59 was relatively reduced on Bid-/- cells. Bid was rapidly cleaved in WT MEF subjected to lytic doses of MAC. Pretreatment of the cells with the pan-caspase inhibitor z-Val-Ala-Asp(OMe)-fluoromethylketone reduced Bid cleavage and cell lysis. These results indicate that complement MAC activates two cell death pathways, one involving caspases and Bid and one that is Bid-independent.
Ziporen
Lea
L
Department of Cell and Developmental Biology, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel.
Donin
Natalie
N
Shmushkovich
Taisia
T
Gross
Atan
A
Fishelson
Zvi
Z
D000818:Animals; D000831:Animals, Newborn; D051023:BH3 Interacting Domain Death Agonist Protein / Q000172:deficiency / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D020169:Caspases / Q000378:metabolism; D016923:Cell Death / Q000276:immunology; D002461:Cell Line, Transformed; D002478:Cells, Cultured; D015938:Complement Membrane Attack Complex / Q000502:physiology*; D005347:Fibroblasts / Q000276:immunology / Q000378:metabolism / Q000473:pathology; D006801:Humans; D007113:Immunity, Innate / Q000235:genetics; D019169:Jurkat Cells; D020014:K562 Cells; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D009336:Necrosis; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology*
D051023:BH3 Interacting Domain Death Agonist Protein; C494814:BID protein, human; D015938:Complement Membrane Attack Complex; D020169:Caspases