Phosphoprotein affinity profiling--a novel method for screening regulators of lipopolysaccharide signaling pathway / 南方医科大学学报

ABSTRACT

<p><b>OBJECTIVE</b>To To establish a method of phosphoprotein affinity profiling for identifying phosphoproteomic differences between Thp-1 cells with or without lipopolysaccharide (LPS) stimulation, aiming to screen potential regulators involved in LPS pathway.</p><p><b>METHODS</b>Thp-1 cells were stimulated with 100 ng/ml PMA for 48 h to induce differentiation into mature macrophages, which, after culture for another 48 h in the absence of PMA, were either treated with 100 ng/ml LPS for 30 min or left untreated. After desalting procedure with ultrafiltration, the phosphoproteins enriched by phosphoprotein metal affinity column (PMAC) of both groups were run on 2-D electrophoresis to find the spots with different phosphorylation status. Finally, some of these spots were identified by mass spectrometry (MS) and subsequent bioinformatic analysis.</p><p><b>RESULTS</b>Compared to untreated Thp-1 cells, LPS stimulated Thp-1 cells showed 29 spots with reproducible alterations on the 2-D map, including 8 representing up-regulated spots, 7 new spots, 10 down-regulated spots, and 4 absent spots. The newly emerged and absent protein spots were subjected to MS analysis, and 4 of them were identified to be involved in various cellular processes such as proteolysis, signal transduction and protein folding. Among these, phosphorylation of proteasome C2 subunit was dramatically up-regulated in LPS-stimulated cells, as was consistent with previous reports; the phosphorylation of Z-DNA-binding protein 1 has not been reported so far and needs further confirmation.</p><p><b>CONCLUSION</b>Phosphoprotein affinity profiling is an attractive method for screening novel regulators involved in LPS signaling pathways and can be widely used in systemic study of signal transduction.</p>