title: Caspase-2 short isoform interacts with membrane-associated cytoskeleton proteins to inhibit apoptosis.
abstract: Caspase-2 (casp-2) is the most conserved caspase across species, and is one of the initiator caspases activated by various stimuli. The casp-2 gene produces several alternative splicing isoforms. It is believed that the long isoform, casp-2L, promotes apoptosis, whereas the short isoform, casp-2S, inhibits apoptosis. The actual effect of casp-2S on apoptosis is still controversial, however, and the underlying mechanism for casp-2S-mediated apoptosis inhibition is unclear. Here, we analyzed the effects of casp-2S on DNA damage induced apoptosis through "gain-of-function" and "loss-of-function" strategies in ovarian cancer cell lines. We clearly demonstrated that the over-expression of casp-2S inhibited, and the knockdown of casp-2S promoted, the cisplatin-induced apoptosis of ovarian cancer cells. To explore the mechanism by which casp-2S mediates apoptosis inhibition, we analyzed the proteins which interact with casp-2S in cells by using immunoprecipitation (IP) and mass spectrometry. We have identified two cytoskeleton proteins, Fodrin and α-Actinin 4, which interact with FLAG-tagged casp-2S in HeLa cells and confirmed this interaction through reciprocal IP. We further demonstrated that casp-2S (i) is responsible for inhibiting DNA damage-induced cytoplasmic Fodrin cleavage independent of cellular p53 status, and (ii) prevents cisplatin-induced membrane blebbing. Taken together, our data suggests that casp-2S affects cellular apoptosis through its interaction with membrane-associated cytoskeletal Fodrin protein.
authors.affiliation: Department of Radiology, The Ohio State University Wexner Medical Center, Columbus, Ohio, United States of America.
authors.forename: Chunhua
authors.initials: C
authors.lastname: Han
authors.forename: Ran
authors.initials: R
authors.lastname: Zhao
authors.forename: John
authors.initials: J
authors.lastname: Kroger
authors.forename: Meihua
authors.initials: M
authors.lastname: Qu
authors.forename: Altaf A
authors.initials: AA
authors.lastname: Wani
authors.forename: Qi-En
authors.initials: QE
authors.lastname: Wang
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D002352:Carrier Proteins / Q000378:metabolism; D053143:Caspase 2 / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D002945:Cisplatin / Q000494:pharmacology*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D008840:Microfilament Proteins / Q000378:metabolism; D010051:Ovarian Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism; D010053:Ovary / Q000187:drug effects / Q000378:metabolism; D013049:Spectrin
chemical_list: D000970:Antineoplastic Agents; D002352:Carrier Proteins; D053143:Caspase 2; D002945:Cisplatin; D008565:Membrane Proteins; D008840:Microfilament Proteins; D013049:Spectrin