Characterization of phosphoproteome of HepG2 cells infected by Klebsiella pneumonia NTUH-K2044 and its capsular polysaccharide.
Date Issued
2009
Date
2009
Author(s)
Sue, Jui-Wen
Abstract
Klebsiella pneumoniae, an enterobacterium, is a gram-negative strain of bacteria that belongs to enterobacteriae. K. pneumoniae is responsible for most cases of hospital-acquired pneumonia, The bacteriae often causes severe pyogenic liver abscess （PLA） that is accompanied with metastatic meningitis or endophthalmitis recently. However, it remains obscure how K. pneumoniae may become virulent in human host and result in liver abscess. It is tentative to suggest that its toxicity rises from its remarkable mucoviscosity, which is modulated by the level of external capsule polysaccharides (CPS). It is possible that once K. pneumoniae attains hypermuscosity, it could not be targeted by immune cells, and thereby leads to severe consequences.n our study, we intend to find the missing link between the CPS of K. pneumonia and PLA pathogenesis by investigating the level and extent of protein phosphorylation in the infected HepG2 cells. We use a virulent strain K. pneumonia NTUH-K2044 which was isolated from a PLA patient in Taiwan, and a hepatoma cell line HepG2 as experiment model. When HepG2 was infected by K. pneumonia NTUH-K2044, the expression of phosphotyrosine protein was immediately upregulated. While HepG2 was infected by CPS extracted from K. pneumonia NTUH-K2044, phosphotyrosine proteins increased to optimum in 150 min. After K. pneumonia NTUH-K2044 infection for 6 hours, HepG2 died. We used a flow cytometry to identify whether cells died of apoptosis. The result showed that the DNA of cells was intact, we speculated, therefore, that cells apoptosis were activated via other pathways.hosphorylation of proteins plays an important role in cellular process by modulating protein function and transmitting signals within cellular pathways and networks. To identify the phosphoproteins involve in the CPS infection, we use S/MS to study the phosphoproteome of infected HepG2. Because the signal intensity phosphoserine and phosphothreonine protein was too high and put a cover over phosphotyrosin in MS/MS analysis, there was no remarkable proteins found in in-gel digestion.
Subjects
Klebsiella pneumoniae
capsule polysaccharide
liver abscess
phosphoproteome
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