Identification of the primary caspase 3 cleavage site in alpha II-spectrin during apoptosis

• Published in: Apoptosis (London) Vol. 8; no. 4; pp. 353 - 361
• Main Authors: WILLIAMS, S. T, SMITH, A. N, CIANCI, C. D, MORROW, J. S, BROWN, T. L
• Format: Journal Article
• Language: English
• Published: Heidelberg Springer 01-08-2003; Springer Nature B.V
• Subjects: Amino acids; Animals; Apoptosis; Apoptosis - physiology; B-Lymphocytes - metabolism; Base Sequence; Biological and medical sciences; Caspase 3; Caspases - metabolism; Cell Line; Cells; Dactinomycin - metabolism; DNA Fragmentation; Fundamental and applied biological sciences. Psychology; Humans; In Situ Nick-End Labeling; Molecular and cellular biology; Mutagenesis, Site-Directed; Nucleic Acid Synthesis Inhibitors - metabolism; Protein Isoforms - metabolism; Sjogren's Syndrome; Spectrin - metabolism; Genetics
• ISSN: 1360-8185; 1573-675X
• DOI: 10.1023/A:1024168901003

Alpha II-spectrin is one of the major proteins responsible for maintaining the cytoskeletal integrity of the cell. The caspase 3-mediated cleavage of alpha II-spectrin during apoptotic cell death may play an important role in altering membrane stability and the formation of apoptotic bodies. In this study, we identified the primary caspase 3 cleavage site in alpha II-spectrin. We found that the transcriptional inhibitor, actinomycin D, induced caspase 3 activation and that caspase 3 activation is coincident with the cleavage of alpha II-spectrin protein at a primary cleavage site. Deletion analysis and site directed mutagenesis identified the primary cleavage site in alpha II spectrin at amino acid 1185 (DETD). The primary caspase 3 cleavage site in alpha II spectrin is conserved in immature and mature B cells. Our results indicate that alpha II-spectrin is initially cleaved at a caspase 3 consensus site and this primary event likely alters the structural conformation of the protein exposing subsequent cleavage sites and altering cytoskeletal integrity. Identification of the primary cleavage site for caspase 3 may help to elucidate the role of alpha II-spectrin in membrane stability and apoptosis as well as provide new insights into alpha II-spectrin autoantibody formation associated with the autoimmune disease, Sjögren's syndrome.