Related Experiment Videos
Zymosan-triggered tyrosine phosphorylation in mouse bone-marrow-derived macrophages is enhanced by respiratory-burst
S P Green1, J A Hamilton, W A Phillips
1University of Melbourne, Department of Medicine, Royal Melbourne Hospital, Parkville, Australia.
Abstract:
We have investigated the relationship between tyrosine phosphorylation and respiratory-burst activity in mouse bone-marrow-derived macrophages (BMM). We demonstrate that zymosan, an agent known to trigger the macrophage respiratory burst, also triggers the activation of tyrosine kinase activity, resulting in rapid tyrosine phosphorylation on numerous proteins, and provide evidence for the role of tyrosine phosphorylation in the triggering of the BMM respiratory burst. Agents, such as tumour necrosis factor alpha (TNF alpha), interferon-gamma (IFN-gamma) or lipopolysaccharide (LPS), which prime the macrophage for an enhanced zymosan-triggered respiratory burst, increase tyrosine phosphorylation triggered by zymosan. The zymosan-triggered tyrosine phosphorylation and respiratory-burst activity were partially suppressed by the tyrosine kinase inhibitors alpha-cyano-3-ethoxy-4-hydroxy-5-phenylmethylcinnamide (ST638) and herbimycin A. In addition, pre-exposure of BMM to vanadate, a phosphotyrosine phosphatase inhibitor, greatly enhanced the ability of zymosan to induce tyrosine phosphorylation and trigger the respiratory burst. These data highlight the importance of the balance between tyrosine kinase and phosphotyrosine phosphatase activity in determining the ultimate level of tyrosine phosphorylation in BMM and suggest that zymosan-triggered tyrosine phosphorylation is an important biochemical signal for triggering of the respiratory burst.
Insights
Tyrosine phosphorylation is crucial for triggering the macrophage respiratory burst. Inhibiting tyrosine kinases suppressed this activity, while inhibiting phosphatases enhanced it, highlighting a key regulatory balance.
Area of Science:
- Immunology
- Cellular Biology
- Biochemistry
Background:
- The macrophage respiratory burst is a critical defense mechanism.
- Tyrosine phosphorylation plays a role in various cellular signaling pathways.
Purpose of the Study:
- To investigate the link between tyrosine phosphorylation and respiratory burst activity in mouse bone-marrow-derived macrophages (BMM).
- To elucidate the role of tyrosine kinase and phosphotyrosine phosphatase activity in regulating this process.
Main Methods:
- Stimulation of BMM with zymosan to trigger respiratory burst.
- Assessment of tyrosine kinase activity and protein tyrosine phosphorylation.
- Use of tyrosine kinase inhibitors (ST638, herbimycin A) and a phosphotyrosine phosphatase inhibitor (vanadate).
Main Results:
- Zymosan activates tyrosine kinase activity, leading to rapid tyrosine phosphorylation and triggering the respiratory burst.
- Priming agents (TNF-α, IFN-γ, LPS) enhance zymosan-induced tyrosine phosphorylation and respiratory burst.
- Tyrosine kinase inhibitors partially suppressed zymosan-triggered activity, while vanadate enhanced it.
Conclusions:
- Tyrosine phosphorylation is a key biochemical signal for triggering the macrophage respiratory burst.
- The balance between tyrosine kinase and phosphotyrosine phosphatase activity is critical for regulating tyrosine phosphorylation levels in BMM.
- These findings offer insights into the molecular mechanisms underlying macrophage activation.