Proteolysis of Fodrin (Non-erythroid Spectrin) during Apoptosis

Abstract

Several recent studies have implicated proteases as important triggers of apoptosis. Thus far, substrates that are cleaved during apoptosis have been elusive. In this report we demonstrate that cleavage of alpha-fodrin (non-erythroid spectrin) accompanies apoptosis, induced by activation via the CD3/T cell receptor complex in a murine T cell hybridoma, ligation of the Fas (CD95) molecule on a human T cell lymphoma line and other Fas-expressing cells, or treatment of cells with staurosporine, dexamethasone, or synthetic ceramide. Furthermore, inhibition of activation-induced apoptosis by pretreatment of T hybridoma cells with antisense oligonucleotides directed against c-myc also inhibited fodrin proteolysis, confirming that this cleavage process is tightly coupled to apoptosis. Fodrin cleavage during apoptosis may have implications for the membrane blebbing seen during this process.

Caspase 8 Activity in Membrane Blebs After Anti-Fas Ligation

“…One type occurs in lymphoid cells and hepatocytes after Fas cross-linking and is blocked by caspase inhibitors. In this case (11,12), caspase 3-mediated fodrin cleavage has been proposed as a mechanism (13,14). A second type of apoptotic blebbing, seen in fibroblasts, PC12 cells, and COS cells, is resistant to caspase inhibitors and is regulated by myosin L chain phosphorylation (15).…”

Changes in nuclear morphology during apoptosis correlate with vimentin cleavage by different caspases located either upstream or downstream of Bcl‐2 action

“…As a control experiment, Jurkat cells were treated first with either the calpain inhibitor, TLCK or TPCK. Although activation of calpain during apoptosis has been observed (Sarin et al 1993;Martin et al 1995), these noncaspase inhibitors showed little inhibition of vimentin cleavage. These results suggest that vimentin is cleaved either by a caspase or by a protease which is activated by a caspase.…”

Caspases: the executioners of apoptosis

“…α-Fodrin, an abundant membrane-associated cytoskeletal protein, is rapidly and specifically cleaved during CD95-and TNF-induced apoptosis, and this appears to be related to the membrane blebbing. Initially it was proposed that fodrin is cleaved by calpain I [127], but the cleavage is probably due to a caspase [128,129]. Fodrin contains several potential caspase cleavage sites, including a DETD S site only nine amino acids away from the proposed calpain cleavage site, which may have led to the initial confusion [128].…”

“…Cleavage of important cytoskeletal proteins, including actin [124,125], Gas2 [126] and fodrin (non-erythroid spectrin) [127][128][129], during apoptosis may induce cell shrinkage and membrane blebbing, and alter cell survival signalling systems. α-Fodrin, an abundant membrane-associated cytoskeletal protein, is rapidly and specifically cleaved during CD95-and TNF-induced apoptosis, and this appears to be related to the membrane blebbing.…”