title: Caspase proteolysis of desmin produces a dominant-negative inhibitor of intermediate filaments and promotes apoptosis.
abstract: Caspase cleavage of key cytoskeletal proteins, including several intermediate filament proteins, triggers the dramatic disassembly of the cytoskeleton that characterizes apoptosis. Here we describe the muscle-specific intermediate filament protein desmin as a novel caspase substrate. Desmin is cleaved selectively at a conserved Asp residue in its L1-L2 linker domain (VEMD downward arrow M(264)) by caspase-6 in vitro and in myogenic cells undergoing apoptosis. We demonstrate that caspase cleavage of desmin at Asp(263) has important functional consequences, including the production of an amino-terminal cleavage product, N-desmin, which is unable to assemble into intermediate filaments, instead forming large intracellular aggregates. Moreover, N-desmin functions as a dominant-negative inhibitor of filament assembly, both for desmin and the structurally related intermediate filament protein vimentin. We also show that stable expression of a caspase cleavage-resistant desmin D263E mutant partially protects cells from tumor necrosis factor-alpha-induced apoptosis. Taken together, these results indicate that caspase proteolysis of desmin at Asp(263) produces a dominant-negative inhibitor of intermediate filaments and actively participates in the execution of apoptosis. In addition, these findings provide further evidence that the intermediate filament cytoskeleton has been targeted systematically for degradation during apoptosis.
authors.affiliation: Division of Endocrinology, Metabolism, and Molecular Medicine, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, Illinois 60611, USA.
authors.forename: Feng
authors.initials: F
authors.lastname: Chen
authors.forename: Roger
authors.initials: R
authors.lastname: Chang
authors.forename: Marcus
authors.initials: M
authors.lastname: Trivedi
authors.forename: Yassemi
authors.initials: Y
authors.lastname: Capetanaki
authors.forename: Vincent L
authors.initials: VL
authors.lastname: Cryns
mesh_terms: D000818:Animals; D017209:Apoptosis; D001224:Aspartic Acid; D053178:Caspase 6; D020169:Caspases / Q000378:metabolism*; D002460:Cell Line; D003893:Desmin / Q000378:metabolism*; D019084:Fluorescent Antibody Technique, Indirect; D005799:Genes, Dominant; D006801:Humans; D015151:Immunoblotting; D051379:Mice; D016297:Mutagenesis, Site-Directed; D010957:Plasmids / Q000378:metabolism; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D051381:Rats; D013997:Time Factors; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism
chemical_list: D003893:Desmin; D014409:Tumor Necrosis Factor-alpha; D001224:Aspartic Acid; C505514:CASP6 protein, human; C505516:Casp6 protein, mouse; C505518:Casp6 protein, rat; D053178:Caspase 6; D020169:Caspases