title: Processing and activation of pro-interleukin-16 by caspase-3.
abstract: Interleukin-16, a proinflammatory cytokine produced in CD8(+) lymphocytes, is synthesized as a precursor protein (pro-IL-16). It is postulated that the C-terminal region of pro-IL-16 is cleaved, releasing bioactive IL-16. To characterize IL-16 cleavage, we transfected COS cells with a cDNA encoding a approximately 50-kDa form of pro-IL-16. Transfected COS cells released a approximately 20-kDa IL-16 cleavage product shown to consist of the 121 C-terminal residues of pro-IL-16 by immunoblotting and amino acid sequencing. Cleaved IL-16, but not pro-IL-16, exhibited lymphocyte chemoattractant activity. A C-terminal approximately 20-kDa IL-16 polypeptide was also released when pro-IL-16 was treated with concanavalin A-stimulated CD8(+) lymphocyte lysate. Cleavage occurred after an Asp, suggesting involvement of a caspase (interleukin-1beta-converting enzyme/CED-3) family protease. Using recombinant caspases and granzyme B, we determined that pro-IL-16 cleavage is mediated only by caspase-3. Relevance to pro-IL-16 processing in primary lymphocytes was supported by identifying the p20 subunit of activated caspase-3 in stimulated CD8(+) lymphocytes and by inhibition of CD8(+) lymphocyte lysate-mediated cleavage with Ac-DEVD-CHO. Pro-IL-16 is a substrate for caspase-3, and cleavage by this enzyme releases biologically active IL-16 from its inactive precursor.
authors.affiliation: Pulmonary Center, Boston University School of Medicine, Boston, Massachusetts 02118, USA. yzhang@bupula.bu.edu
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.forename: D M
authors.initials: DM
authors.lastname: Center
authors.forename: D M
authors.initials: DM
authors.lastname: Wu
authors.forename: W W
authors.initials: WW
authors.lastname: Cruikshank
authors.forename: J
authors.initials: J
authors.lastname: Yuan
authors.forename: D W
authors.initials: DW
authors.lastname: Andrews
authors.forename: H
authors.initials: H
authors.lastname: Kornfeld
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D016282:Aspartic Acid Endopeptidases / Q000378:metabolism; D018414:CD8-Positive T-Lymphocytes / Q000187:drug effects / Q000378:metabolism; D019556:COS Cells; D053148:Caspase 3; D020169:Caspases; D003208:Concanavalin A / Q000494:pharmacology; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D006868:Hydrolysis; D019410:Interleukin-16 / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D011498:Protein Precursors / Q000737:chemistry / Q000378:metabolism*; D011499:Protein Processing, Post-Translational; D011994:Recombinant Proteins / Q000737:chemistry / Q000378:metabolism
chemical_list: D019410:Interleukin-16; D011498:Protein Precursors; D011994:Recombinant Proteins; D003208:Concanavalin A; D053148:Caspase 3; D020169:Caspases; D003546:Cysteine Endopeptidases; D016282:Aspartic Acid Endopeptidases