| Mitogen activated protein kinase (MAPK) signal system is the main signal transduction system in mammalian cells. It transduces varied signals from extracell into nucleus, and regulates gene expressing, thus induces reactions of the cell to stimulations. p38 MAPK pathway is one of the important branch of MAPK. p38 was discovered and named in 1993 because of its molecule weight, there was a band at 38kD when researchers studied on tyrosine phosphorylation of protein induced by LPS. Han J cloned p38 gene in 1994 and studied on its structure and functions, then they found that p38 is a member of MAPK superfamily of mammalian. Studies indicate that p38 plays an important role on many physiological and pathological processes including inflammation, stress response, cell survival, apoptosis, proliferation, cell cycle and ischemia/reperfusion. Activation of p38 MAPK participate not only in regulating response of inflammation and stress, expressing transcriptional factor genes, reforming cytoskeleton, but also in multifarious disease courses of infection, ischemia/reperfusion injury, cardiac muscle hypertrophy, neurological disease, trauma recovery, structure rebuilding, and soon.p38 has comprehensive and complicated biological functions, leads researchers to study on its signal transduction mechanism. Revealing themechanism of p38 signal transduction, it will be a great help to clarify the pathological mechanism of lethal diseases such as endotoxic shock, and provide new ideas on screen drugs for these diseases.Intracellular signals transduce through cascade amplification effects consisting of a series of biochemical events mainly including protein phosphorylation, protein-protein interaction, signal complexes formation and gene expression inducing and/or inhibiting, thus cause functional changes in cell proliferation, differentiation and cell cycle. Consequently studying on the role of biological signal molecule complexes on signal transduction passway, especially complexes of protein-protein interaction, attracts many researchers' attention. Confirming each signal molecule and composition of certain complex in these signal transduction pathways, will give a comprehensive cognition of the complicated signal network system consist of many signal molecules. Recognizing proteins interacted with p38 will help us understand protein molecule composition of p38 MAPK pathway and find new relationships between some proteins and p38.Development of the techniques on biological mass-spectrum (MS) and proteomics, and efficient use of both with other biochemical methods made it easier to separate and identify trace amounts of protein. It is possible to study protein signal molecule deeply by such strong advancement. In this study, through combining MS with coimmunoprecipitation methods efficiently, we get protein complexes coimmunoprecipitated with p38 from agarose beads. Then we separate them by SDS-PAGE, and identify proteins with MS at last, thus we get protein profile interacting with p38.This method is proved to be simple and efficiency. Protein extract from tissures of endotoxic shock animal model induced by LPS or shock model induced by blood loss and control team pass through affinity column full of purified His-tagged p38, then proteins interacting with p38 can be co-precipitated with agarose beads. After separated by SDS-PAGE, the protein bands were cut, digested by trypsin, and identified by MALDI-TOF MS. Two proteins were found in lung extract of shock model changedsignificantly virs control, one is C-reactive protein (CRP), the other is endogenous p38 mitogen activated protein kinase. At the same time, there are two protein bands changed in heart extract of shock model, one is ATP synthase alpha chain, and the other is hemoglobin beta chain.We further observed the localization and expression of CRP in endothelial cell (EC). CRP was mainly distributed in EC cellular cortex under normal condition, with uniform fluorescence staining and smooth membrane edge, and the nuclear area has weak uniform staining. EC...
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