Protein phosphorylation profiling identifies potential mechanisms for direct immunotoxicity.

Area of Science:

• Immunotoxicology
• Cellular Signaling
• Molecular Biology

Background:

• Protein tyrosine kinases (PTKs) are crucial in cellular signaling pathways.
• Chemical toxicants can disrupt cellular processes by modulating PTK activity.
• Understanding chemical-induced immunotoxicity requires identifying affected signaling pathways.

Purpose of the Study:

• To identify common cellular signaling pathways involved in chemical-induced direct immunotoxicity.
• To investigate the effects of immunotoxicants and immunosuppressive drugs on tyrosine kinase signaling.
• To elucidate the mechanism of action of specific immunotoxicants on key signaling nodes.

Main Methods:

• Antibody array-based profiling of 28 receptor tyrosine kinases and 11 signaling nodes in Jurkat T-cells.
• Assessment of chemical effects on protein phosphorylation.
• Flow cytometry and Western blotting to analyze the mTOR-p70S6K-RPS6 pathway.
• Comparison of proteomic data with transcriptomic data.
• CXCL12 chemotaxis assay to confirm effects on leukocyte migration.

Main Results:

• Immunotoxicants and immunosuppressive drugs commonly regulated phosphorylation of ribosomal protein S6 (RPS6), Akt, Src, and p44/42 kinases.
• RPS6 phosphorylation showed the most significant regulation.
• The immunotoxicant TBTO and rapamycin inactivated RPS6 through distinct mechanisms.
• Protein phosphorylation data correlated well with transcriptome data at the pathway level.
• TBTO was found to affect ribosome biogenesis and leukocyte migration.

Conclusions:

• Chemicals can induce immunotoxicity by targeting common signaling pathways, particularly those involving RPS6.
• TBTO impacts cellular processes like ribosome biogenesis and leukocyte migration via distinct molecular mechanisms.
• Integrated analysis of proteomic and transcriptomic data provides insights into chemical toxicity mechanisms.