| First Author | Ohama T | Year | 2010 |
| Journal | J Biol Chem | Volume | 285 |
| Issue | 12 | Pages | 8711-8 |
| PubMed ID | 20100830 | Mgi Jnum | J:162276 |
| Mgi Id | MGI:4818541 | Doi | 10.1074/jbc.M109.099788 |
| Citation | Ohama T, et al. (2010) Endotoxin conditioning induces VCP/p97-mediated and inducible nitric-oxide synthase-dependent Tyr284 nitration in protein phosphatase 2A. J Biol Chem 285(12):8711-8 |
| abstractText | Endotoxins activate Toll-like receptors and reprogram cells to be refractory to secondary exposure. Here we found that activation of different Toll-like receptors elicited a time- and dose-dependent increase in the levels of the protein phosphatase 2A catalytic subunit (PP2Ac) but not its partner A subunit. We purified the lipopolysaccharide-induced form of PP2A by chromatography plus immunoprecipitation and used mass spectrometry to identify VCP/p97 as a novel partner for PP2Ac. Endogenous VCP/p97 and PP2Ac were co-immunoprecipitated from primary murine macrophages and human lymphocytes. GST-VCP/p97 bound purified PP2A in pulldown assays, showing direct protein-protein interaction. Endotoxin conditioning of macrophages induced formation of 3-nitrotyrosine in the PP2Ac associated with VCP/p97, a response severely reduced in macrophages from iNOS knock-out mice. The reaction of purified PP2A with peroxynitrite dissociated the A subunit, and 3-nitro-Tyr(284) was identified in PP2Ac by mass spectrometry. Myc-PP2Ac (Y284F) expressed in cells was resistant to peroxynitrite-induced nitration and reduction of A subunit binding. Transient expression of either VCP/p97 or PP2Ac was sufficient to elevate levels of the dual specificity phosphatase DUSP1, reduce p38 MAPK activation, and suppress tumor necrosis factor-alpha release. We propose that VCP/p97-mediated Tyr nitration of PP2A increases the levels of phosphatases PP2A and DUSP1 to contribute to the refractory response of conditioned cells. |
