BID regulates AIF-mediated caspase-independent necroptosis by promoting BAX activation

Abstract

Alkylating DNA-damage agents such as N-methyl-N 0 -nitro-N 0 -nitrosoguanidine (MNNG) trigger necroptosis, a newly defined form of programmed cell death (PCD) managed by receptor interacting protein kinases. This caspase-independent mode of cell death involves the sequential activation of poly(ADP-ribose) polymerase-1 (PARP-1), calpains, BAX and AIF, which redistributes from mitochondria to the nucleus to promote chromatinolysis. We have previously demonstrated that the BAX-mediated mitochondrial release of AIF is a critical step in MNNG-mediated necroptosis. However, the mechanism regulating BAX activation in this PCD is poorly understood. Employing mouse embryonic knockout cells, we reveal that BID controls BAX activation in AIF-mediated necroptosis. Indeed, BID is a link between calpains and BAX in this mode of cell death. Therefore, even if PARP-1 and calpains are activated after MNNG treatment, BID genetic ablation abolishes both BAX activation and necroptosis. These PCD defects are reversed by reintroducing the BID-wt cDNA into the BID À/À cells. We also demonstrate that, after MNNG treatment, BID is directly processed into tBID by calpains. In this way, calpain non-cleavable BID proteins (BID-G70A or BID-D68-71) are unable to promote BAX activation and necroptosis. Once processed, tBID localizes in the mitochondria of MNNG-treated cells, where it can facilitate BAX activation and PCD. Altogether, our data reveal that, as in caspase-dependent apoptosis, BH3-only proteins are key regulators of caspase-independent necroptosis. Cell Death and Differentiation (2012) 19, 245-256; doi:10.1038/cdd.2011.91; published online 8 July 2011When and how a cell dies is one of the essential questions to understand the biology of the cell. A cell is considered dead when the integrity of its plasma membrane is compromised, when its fragments are engulfed by an adjacent or a professional cell or when its components, including the nucleus, are fragmented. It is more complicated to outline how a cell could die. Historically, two major types of cell death have been distinguished: apoptosis, a controlled or programmed cell death (PCD), and necrosis, an uncontrolled or accidental death. 1 Cell biologists have particularly focused their attention on apoptotic PCD, helping to characterize it at both genetic and biochemical levels. 2 Fascinatingly, the use of apoptotic inhibitors or cells that are deficient in key apoptotic molecules has revealed the existence of new PCD pathways. As a consequence, active forms of cell death started to be referred to as caspase-dependent or caspase-independent. 3 More recently, it has been accepted that necrosis is more than an unregulated type of death. Indeed, a cell can use different mechanisms/pathways with underlying apoptotic or necrotic features to accomplish its proper demise. 4 The analysis of the tumor necrosis factor (TNF) signaling path has shed new light on the existence of PCD pathways with necrotic features. When TNF binds its receptor, two ways can be engaged: (i) caspase-dependent a...

Novel Mitochondrial Targets for Neuroprotection

“…A limited extent or duration of elevated Ca 2 + may not result in the extent of bioenergetic impairment necessary for evoking acute cell death but can promote caspaseindependent apoptosis through calpain-mediated mitochondrial release of apoptosis inducing factor (AIF) (Polster et al, 2005). Calpains can also cleave inactive BH3 domain-only proteins, forming active peptides, e.g., truncated Bid (tBid), which bind to proapoptotic and antiapoptotic proteins, e.g., Bax and Bcl2, resulting in outer membrane permeabilization and release of cytochrome c, AIF, and other proteins that trigger either caspase-dependent or caspase-independent programmed cell death (Krajewska et al, 2004;Cabon et al, 2012). A greater mitochondrial insult, which leads to delayed neuronal Ca 2 + deregulation, is more apt to induce rapid necrosis, particularly when PTP opening causes irreversible mitochondrial inner membrane depolarization and osmotic mitochondrial lysis (Pivovarova and Andrews, 2010).…”

Cordycepol C Induces Caspase-Independent Apoptosis in Human Hepatocellular Carcinoma HepG2 Cells

“…Bax was also found to be indispensable for AIF-mediated cell death. 13,14) On the contrary, the antiapoptotic molecules such as Bcl-2 and Bcl-xL can be activated to prevent the conformational change and oligomerization of Bax and Bak. 44,45) In this study, we found cordycepol C could induce the disruption of Δψ m and the translocation of Bax from cytoplasm to mitochondria (Fig.…”

“…8,12,13,16,45,46) AIF can induce chromatin condensation and cleavage of DNA into high molecular weight fragments (50-300 kb), while endonuclease G can produce oligonucleosomal DNA fragments. 8,16) Our results revealed that cordycepol C induced the release of AIF and Endo G from the mitochondria and their translocation to the nucleus in a time-dependent manner (Fig.…”

“…11,12) The proapoptotic Bcl-2 family member Bax is activated by Bid and plays an indispensable role in AIF-mediated programmed necrosis. 13,14) Meanwhile, endonuclease G (Endo G), a nuclease, also translocates into the nucleus and cleaves chromatin DNA into nucleosomal fragments in apoptotic cells. [15][16][17] Endo G induces DNA degradation through a caspase-independent pathway, in a manner similar to AIF.…”

Hormesis, Cell Death, and Regenerative Medicine for Neurodegenerative Diseases

“…2) (Patterson et al 2000;Wabnitz et al 2010;Lee et al 2010). The key regulators of caspase-independent apoptosis are located on the mitochondria membranes, whose integrity (mitochondrial outer membrane permeabilization (MOMP)) is regulated by multiple proteins and processes, including Bcl-2 family members (Esposti 2010), BH3-only proteins (Cabon et al 2012), tumor suppressor protein P53 (Galluzzi et al 2008a;Galluzzi et al 2011), Protein kinase Cs (AllenPetersen et al 2010;Paoletti et al 2010), epigenetic perturbations (Yelamanchili et al 2010;Tenedini et al 2010;Sancho-Pelluz et al 2010;Lei et al 2010;Lanzillotta et al 2010), and cell cycle perturbations ( Fig. 2) (Mitchell et al 2010).…”