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09:04
Detection of Neu1 Sialidase Activity in Regulating TOLL-like Receptor Activation
Published on: September 7, 2010
New vistas on TLR9 activation
1Institute of Medical Microbiology, Immunology and Hygiene, Technical University Munich, Munich, Germany. h.wagner@lrz.tum.de
European Journal of Immunology
|September 29, 2011
Summary
Toll-like receptor 9 (TLR9) undergoes cleavage in macrophages, a process not affected by inhibitory oligonucleotides. This cleavage impacts CpG-ligand binding and differential activation by various CpG-oligodeoxynucleotides (ODNs).
Area of Science:
- Immunology
- Molecular Biology
Background:
- Toll-like receptor 9 (TLR9) is crucial for innate immunity, recognizing microbial DNA.
- TLR9 trafficking from the endoplasmic reticulum (ER) to endolysosomal compartments is essential for its function.
- The transmembrane protein UNC93B1 facilitates TLR9 ER export.
Purpose of the Study:
- To investigate the proteolytic cleavage of TLR9.
- To elucidate the role of TLR9 cleavage in CpG-oligodeoxynucleotide (ODN) binding and activation.
- To explain the differential activation efficiency of phosphorothioated (PS) and phosphorodiester (PD) CpG-ODNs.
Main Methods:
- Analysis of TLR9 cleavage in RAW 264.7 macrophages.
- Assessment of inhibitory oligonucleotide (IN-ODN) effects on TLR9 cleavage and CpG-ligand binding.
- Comparison of activation by PS- and PD-CpG-ODNs.
Main Results:
- TLR9 ectodomain (TLR9ecto) is proteolytically cleaved after trafficking.
- Cleaved TLR9 is detected in resting RAW 264.7 macrophages.
- IN-ODNs do not influence TLR9 cleavage but inhibit CpG-ligand binding to the C-terminal fragment.
- Differences in PS- and PD-CpG-ODN activation efficiency are observed.
Conclusions:
- TLR9 cleavage is a post-trafficking event that influences ligand interaction.
- The proposed model explains differential CpG-ODN binding and activation based on their chemical backbone.
- Understanding TLR9 processing is key to developing targeted immunotherapies.
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