Myeloid-related protein-14 is a p38 MAPK substrate in human neutrophils.

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Citation

Lominadze G, Rane MJ, Merchant M, Cai J, Ward RA, McLeish KR

Myeloid-related protein-14 is a p38 MAPK substrate in human neutrophils.

J Immunol. 2005 Jun 1;174(11):7257-67.

PubMed ID
15905572 [ View in PubMed
]
Abstract

The targets of the p38 MAPK pathway that mediate neutrophil functional responses are largely unknown. To identify p38 MAPK targets, a proteomic approach was applied in which recombinant active p38 MAPK and [(32)P]ATP were added to lysates from unstimulated human neutrophils. Proteins were separated by two-dimensional gel electrophoresis, and phosphoproteins were visualized by autoradiography and identified by MALDI-TOF. Myeloid-related protein-14 (MRP-14) was identified as a candidate p38 MAPK substrate. MRP-14 phosphorylation by p38 MAPK was confirmed by an in vitro kinase reaction using purified MRP-14/MRP-8 complexes. The site of MRP-14 phosphorylation by p38 MAPK was identified by tandem mass spectrometry and site-directed mutagenesis to be Thr(113). MRP-14 phosphorylation by p38 MAPK in intact neutrophils was confirmed by [(32)P]orthophosphate loading, followed by fMLP stimulation in the presence and absence of a p38 MAPK inhibitor, SB203580. Confocal microscopy of Triton X-100 permeabilized neutrophils showed that a small amount of MRP-14 was associated with cortical F-actin in unstimulated cells. fMLP stimulation resulted in a p38 MAPK-dependent increase in MRP-14 staining at the base of lamellipodia. By immunoblot analysis, MRP-14 was present in plasma membrane/secretory vesicle fractions and gelatinase and specific granules, but not in azurophil granules. The amount of MRP-14 associated with plasma membrane/secretory vesicle and gelatinase granule fractions increased after fMLP stimulation in a p38 MAPK-dependent manner. Direct phosphorylation of the MRP-14/MRP-8 complex by p38 MAPK increased actin binding in vitro by 2-fold. These results indicate that MRP-14 is a potential mediator of p38 MAPK-dependent functional responses in human neutrophils.

DrugBank Data that Cites this Article

Polypeptides
NameUniProt ID
Mitogen-activated protein kinase 14Q16539Details
Protein S100-A9P06702Details