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Processing and activation of pro-interleukin-16 by caspase-3
1Pulmonary Center, Boston University School of Medicine, Boston, Massachusetts 02118, USA. yzhang@bupula.bu.edu
The Journal of Biological Chemistry
|February 14, 1998
Summary
Interleukin-16 (IL-16) is processed from its precursor by caspase-3, releasing bioactive IL-16. This cleavage, occurring in CD8(+) lymphocytes, generates the active cytokine responsible for lymphocyte chemoattraction.
Area of Science:
- Immunology
- Molecular Biology
- Cell Biology
Background:
- Interleukin-16 (IL-16) is a proinflammatory cytokine produced by CD8(+) lymphocytes.
- IL-16 is synthesized as an inactive precursor protein (pro-IL-16).
- Bioactive IL-16 is thought to be released by cleavage of the pro-IL-16 C-terminal region.
Purpose of the Study:
- To characterize the cleavage of pro-IL-16.
- To identify the specific protease responsible for pro-IL-16 processing.
- To confirm the biological activity of cleaved IL-16.
Main Methods:
- Transfection of COS cells with pro-IL-16 cDNA.
- Immunoblotting and amino acid sequencing to identify cleavage products.
- Treatment of pro-IL-16 with lymphocyte lysates and recombinant proteases (caspases, granzyme B).
- Detection of activated caspase-3 in stimulated CD8(+) lymphocytes.
Main Results:
- A ~20-kDa IL-16 cleavage product, comprising the 121 C-terminal residues, was released from transfected cells.
- Cleaved IL-16, but not pro-IL-16, demonstrated lymphocyte chemoattractant activity.
- Pro-IL-16 cleavage was mediated exclusively by caspase-3.
- Activated caspase-3 was identified in stimulated CD8(+) lymphocytes, and cleavage was inhibited by a caspase-3 inhibitor.
Conclusions:
- Pro-IL-16 is a substrate for caspase-3.
- Caspase-3 cleavage releases biologically active IL-16 from its inactive precursor.
- This mechanism is relevant to pro-IL-16 processing in primary lymphocytes.