RRC ID 2057
Author Himeji D, Horiuchi T, Tsukamoto H, Hayashi K, Watanabe T, Harada M.
Title Characterization of caspase-8L: a novel isoform of caspase-8 that behaves as an inhibitor of the caspase cascade.
Journal Blood
Abstract Caspase-8 (Fas-associating protein with death domain-like interleukin-1beta- converting enzyme [FLICE]/MACH/Mch5) belongs to a family of cysteine proteases presumed to be the apex of the apoptotic signaling pathways. We recently reported the presence of a novel isoform of caspase-8, named caspase-8L, generated by the alternative splicing of human caspase-8 gene, from human peripheral blood lymphocytes by reverse transcriptase-polymerase chain reaction. We herein report a functional analysis of caspase-8L in the Fas-mediated apoptotic pathway. Caspase-8L is missing the catalytic site of caspase-8 but retains 2 N-terminal repeats of the death-effector domain. The caspase-8L messenger RNA was detected in various tissues but not in any cell lines examined. In human peripheral blood lymphocytes, caspase-8L was strongly suggested to be expressed at the protein level. In MCF-7 cells, caspase-8L transfection itself did not affect cell viability but instead inhibited the apoptosis induced by the cotransfection of caspase-8 in a dominant negative manner. Moreover, Fas-mediated apoptosis was inhibited in caspase-8L-transfected Jurkat cells, which were associated with a reduction in the caspase-8 catalytic activity. In vitro binding assays demonstrated that caspase-8L bound to FADD (Fas-associating protein with death domain) and caspase-8a and blocked the binding of caspase-8 to FADD. In in vivo binding assays, transfected caspase-8L bound to endogenous FADD. Thus, caspase-8L acts as an inhibitor of caspase-8 by interfering with the binding of caspase-8 to FADD and is involved in the regulation of Fas-mediated apoptosis.
Volume 99(11)
Pages 4070-8
Published 2002-6-1
PMID 12010809
MeSH Amino Acid Sequence Animals Apoptosis Breast Neoplasms COS Cells Caspase 8 Caspase 9 Caspase Inhibitors* Caspases / chemistry Caspases / genetics* Caspases / metabolism Cercopithecus aethiops Cloning, Molecular DNA, Complementary Female Genetic Vectors Humans Isoenzymes / chemistry Isoenzymes / genetics Isoenzymes / metabolism Lymphocytes / cytology Lymphocytes / enzymology Lymphocytes / immunology Molecular Sequence Data Protein Biosynthesis Recombinant Proteins / chemistry Recombinant Proteins / metabolism Reverse Transcriptase Polymerase Chain Reaction Sequence Alignment Sequence Homology, Amino Acid Transcription, Genetic Tumor Cells, Cultured fas Receptor / immunology
IF 16.601
Times Cited 51
DNA material pAxCAhFADD (RDB02007)