Membrane Proteome Analysis of Cerulein-Stimulated Pancreatic Acinar Cells: Implication for Early Event of Acute Pancreatitis

BACKGROUND/AIMS: Cerulein pancreatitis is similar to human edematous pancreatitis with dysregulation of the production and secretion of digestive enzymes, edema formation, cytoplasmic vacuolization and the death of acinar cells. We hypothesized that membrane proteins may be altered as the early event during the induction of acute pancreatitis. Present study aims to determine the differentially expressed proteins in the membranes of cerulein-treated pancreatic acinar cells. METHODS: Pancreatic acinar AR42J cells were treated with 10(-8) M cerulein for 1 hour. Membrane proteins were isolated from the cells and separated by two-dimensional electrophoresis using pH gradients of 5-8. Membrane proteins were identified by matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) analysis of the peptide digests. The differentially expressed proteins, whose expression levels were more or less than three-fold in cerulein-treated cells, were analyzed. RESULTS: Two differentially expressed proteins (mannan-binding lectin-associated serine protease-2, heat shock protein 60) were up-regulated while four proteins (protein disulfide isomerase, gamma-actin, isocitrate dehydrogenase 3, seven in absentia homolog 1A) were down-regulated by cerulein treatment in pancreatic acinar cells. These proteins are related to cell signaling, oxidative stress, and cytoskeleton arrangement. CONCLUSIONS: Oxidative stress may induce cerulein-induced cell injury and disturbances in defense mechanism in pancreatic acinar cells.

Profiling Membrane Proteome of Macrophages by One-dimensional PAGE and Liquid Chromatography-Tandem Mass Spectrometry / 中国生物工程杂志

Macrophages are involved in many important biological processes and membrane proteins are the key effector molecules for their functions. However, membrane proteins are difficult to analyze by 2-DE based method because of their intrinsic tendency to self-aggregate during the first dimension separation (IEF). To circumvent the obstacle hampering membrane protein analysis, we combined one-dimensional SDS-PAGE with capillary liquid chromatography-tandem mass spectrometry (LC-MS/MS). Using this technique, we identified 458 GO annotated membrane proteins with extremely high confidence, including most known markers of peritoneal macrophages (e.g., CD11b, F4/80, CD14, CD18, CD86, CD44, CD16 and Toll-like receptor). Thirteen other CD antigens and 18 Ras-related small GTPase were also identified. In addition to those known macrophage membrane proteins, a significant number of novel proteins have also been identified. This research provides a valuable data set of macrophage membrane proteins, thus allowing for more comprehensive study of membrane proteins and a better understanding of the function mechanisms of macrophages in many biological processes.

Identification of Leukemia Surface Proteins Using a Proteomic Technique

BACKGROUND: Numerous cell surface proteins of leukemia cells such as CD33 and CD52 have been identified as diagnostic and therapeutic targets. Thus the profiling of the cell surface proteome and proteins restricted to specific leukemia(s) can provide a way to identify novel targets for leukemia diagnosis and therapy. However, there is a lack of data pertaining to the comprehensive analysis of surface membrane proteins because there are few effective strategies for profiling surface membrane proteomes. METHODS: We report on the application of quantitative proteomic techniques that incorporate affinity-capture and purification on monomeric avidin columns to identify all biotinylated cell surface proteins from leukemia cell lines. RESULTS: An analysis of a subset of biotinylated proteins among the different human leukemia cell lines using matrix-assisted laser desorption ionization and tandem mass spectrometry identified, among others, some widely expressed proteins in leukemia cells, such as CD11a, CD11c, CD18, CD31, CD44, and CD147, as well as a set of proteins identified as chaperone proteins, including HSP90, GRP78, GRP75, HSP70, HSP60 and protein disulfide isomerases. On the basis of their known functional roles, several of these proteins may participate in the progression of leukemogenesis and should be considered as potential markers of leukemia. CONCLUSION: Comprehensive profiling of the leukemia cell surface proteome provides an effective approach for the identification of commonly occurring proteins as well as proteins with restricted expression patterns to a specific cell line.