CD23 shedding: requirements for substrate recognition and inhibition by dipeptide hydroxamic acids
R J Mayer1, P L Flamberg, S R Katchur
1GlaxoSmithKline Pharmaceuticals, Department of Immunology, King of Prussia, PA 19406, USA. ruth_j_mayer@sbphrd.com
Summary
The low affinity IgE receptor (CD23) is cleaved from cell surfaces, impacting IgE synthesis. Selective inhibitors potently block this CD23 processing, offering therapeutic potential.
Area of Science:
- Immunology
- Molecular Biology
- Biochemistry
Background:
- CD23, the low-affinity IgE receptor (FcεRII), is a Type II extracellular protein expressed on B cells, monocytes, and macrophages.
- Cleavage of CD23 from the cell surface generates soluble fragments involved in regulating IgE synthesis.
- CD23 processing is mediated by a metalloprotease, similar to the cleavage of other cell surface molecules like TNF-alpha.
Purpose of the Study:
- To investigate the biochemical mechanisms of CD23 cleavage from the cell surface.
- To identify factors influencing CD23 processing, including sequence and domain effects.
- To discover and characterize inhibitors of CD23 processing.
Main Methods:
- Biochemical characterization of CD23 cleavage activity.
- Analysis of specific CD23 mutants to determine cleavage determinants.
- Screening and identification of selective dipeptide hydroxamic acid inhibitors.
Main Results:
- Both local sequence and distal domains of CD23 influence its cleavage.
- Selective dipeptide hydroxamic acid inhibitors were identified.
- These inhibitors demonstrated potent and selective inhibition of CD23 processing.
Conclusions:
- CD23 processing is a regulated event influenced by its molecular structure.
- The identified inhibitors represent a promising strategy for targeting CD23-mediated processes.
- Inhibiting CD23 processing may offer a novel approach for modulating IgE synthesis and related conditions.
