Caspase cleavage of the Golgi stacking factor GRASP65 is required for Fas/CD95-mediated apoptosis

Abstract

GRASP65 (Golgi reassembly and stacking protein of 65 KDa) is a cis-Golgi protein with roles in Golgi structure, membrane trafficking and cell signalling. It is cleaved by caspase-3 early in apoptosis, promoting Golgi fragmentation. We now show that cleavage is needed for Fas-mediated apoptosis: expression of caspase-resistant GRASP65 protects cells, whereas expression of membrane proximal caspase-cleaved GRASP65 fragments dramatically sensitises cells. GRASP65 coordinates passage through the Golgi apparatus of proteins containing C-terminal hydrophobic motifs, via its tandem PDZ type ‘GRASP' domains. Fas/CD95 contains a C-terminal leucine–valine pairing so its trafficking might be coordinated by GRASP65. Mutagenesis of the Fas/CD95 LV motif reduces the number of cells with Golgi-associated Fas/CD95, and generates a receptor that is more effective at inducing apoptosis; however, siRNA-mediated silencing or expression of mutant GRASP65 constructs do not alter the steady state distribution of Fas/CD95. We also find no evidence for a GRASP65–Fas/CD95 interaction at the molecular level. Instead, we find that the C-terminal fragments of GRASP65 produced following caspase cleavage are targeted to mitochondria, and ectopic expression of these sensitises HeLa cells to Fas ligand. Our data suggest that GRASP65 cleavage promotes Fas/CD95-mediated apoptosis via release of C-terminal fragments that act at the mitochondria, and we identify Bcl-XL as a candidate apoptotic binding partner for GRASP65.

The oncolytic compound LTX-401 targets the Golgi apparatus

“…What this signal might be remains to be clarified. Past studies have shown that Golgi can release ganglioside GD3, 19 BAX 20 and active caspase-2 (ref. 21) among other factors, 22 suggesting that Golgi can trigger cell death through a variety of distinct mechanisms.…”

Molecular Mechanism Underlying Aβ Immunotherapy: Implications for the Toxic Action of Aβ Oligomers

“…As shown in Figure 1, sortilin forms a death signaling receptor with p75 NTR in response to AβOs, inducing p75 NTR -mediated apoptosis via Go, c-Jun N-terminal kinase (JNK), NADPH oxidase, and caspase-3-released caspases [51]. Recently, Sotthibundhu et al have NTR -sortilin death receptors are formed on the neuronal membrane [14], inducing p75 NTR -mediated apoptosis via Go, c-Jun N-terminal kinase 3 (JNK3), caspase-3-released caspases [51].The activated caspase-3 cleaves Beclin1, which attenuates the autophagy, whereas the resulting Beclin1-C causes mitochondria-mediated apoptosis [53][54][55][56][57][58]. Sortilin induces endocytosis of AβOs [14] into lysosomes [65], resulting in lysosomal leakage [12] and the subsequent mitochondrial apoptosis [12].…”

“…Sortilin induces endocytosis of AβOs [14] into lysosomes [65], resulting in lysosomal leakage [12] and the subsequent mitochondrial apoptosis [12]. In addition to the cleavage of Beclin1 [53][54][55][56][57][58], the resulting activated caspase-3 causes the cleavage of tau [61][62][63], followed by tau assembly [64,65] and phosphorylation [11,14,60]. Incomplete chaperone-mediated autophagy of tau [64] also induces the generation of amyloidogenic fragments that can self-assemble and phosphorylated by AβOs leaked from lysosomes.…”

“…NTR signaling and Aβ1-42-induced toxicity in hippocampal neurons in vitro and in cholinergic basal forebrain neurons in vivo [52]. During such apoptotic processes, activated caspases also result in the production of C-terminal fragment of Beclin1 (Beklin1-C) [53,54]. Beclin1 cleavage inactivates the autophagic function of Beclin1, whereas Beklin1-C acquires apoptosisinducing activity by translocating from the cytosol to the mitochondria, accelerating apoptosis probably via the enhancement of the release of cytochrome C [55][56][57].…”

Hormesis, Cell Death, and Regenerative Medicine for Neurodegenerative Diseases

“…The initiator caspases, caspase 8 and caspase 9, are derived from procaspase 8 and procaspase 9, which will activate the effector caspases, such as caspase 3, and caspase 7 (Sivananthan et al 2010). The activated effector caspases then cleave a subset of more than 100 cellular proteins which are important for cell structure, cellular repair, and cell cycle related proteins (Degterev et al 2003), causing arrest of vital cellular functions as well as lethal catabolic reactions (Martins et al 2011;Cheng et al 2010;Tadokoro et al 2010;Boatright et al 2003). In mammals, the caspase-dependent apoptosis is further subcategorized into extrinsic pathway (death receptor pathway) and intrinsic pathway (mitochondria pathway) depending upon the source of the stress signals (Fig.…”