Differential expression of proteins in rat plasma exposed to benzene

Cytoskeletal proteins: shaping progression of hepatitis C virus-induced liver disease

Hepatitis C virus (HCV) infection, which results in chronic hepatitis C (CHC) in most patients (70-85%), is a major cause of liver disease and remains a major therapeutic challenge. The mechanisms determining liver damage and the key factors that lead to a high rate of CHC remain imperfectly understood. The precise role of cytoskeletal (CS) proteins in HCV infection remains to be determined. Some studies including our recent study have demonstrated that changes occur in the expression of CS proteins in HCV-infected hepatocytes. A variety of host proteins interact with HCV proteins. Association between CS and HCV proteins may have implications in future design of CS protein-targeted therapy for the treatment for HCV infection. This chapter will focus on the interaction between host CS and viral proteins to signify the importance of this event in HCV entry, replication and transportation.

iTRAQ-based proteomic profiling of human serum reveals down-regulation of platelet basic protein and apolipoprotein B100 in patients with hematotoxicity induced by chronic occupational benzene exposure

Benzene is an important industrial chemical and an environmental contaminant, but the pathogenesis of hematotoxicity induced by chronic occupational benzene exposure (HCOBE) remains to be elucidated. To gain an insight into the molecular mechanisms and developmental biomarkers for HCOBE, isobaric tags for relative and absolute quantitation (iTRAQ) combined with two-dimensional liquid chromatography-tandem mass spectrometry (2D-LC-MS/MS) were utilized. Identification and quantitation of differentially expressed proteins between HCOBE cases and healthy control were thus made. Expressions of selected proteins were confirmed by western blot and further validated by ELISA. A total of 159 unique proteins were identified (≥95% confidence), and relative expression data were obtained for 141 of these in 3 iTRAQ experiments, with fifty proteins found to be in common among 3 iTRAQ experiments. Plasminogen (PLG) was found to be significantly up-regulated, whereas platelet basic protein (PBP) and apolipoprotein B100 (APOB100) were significantly down-regulated in the serum of HCOBE cases. Additionally, the altered proteins were associated with the molecular functions of binding, catalytic activity, enzyme regulator activity and transporter activity, and involved in biological processes of apoptosis, developmental and immune system process, as well as response to stimulus. Furthermore, differential expressions of PLG, PBP and APOB100 were confirmed by western blot, and the clinical relevance of PBP and APOB100 with HCOBE was validated by ELISA. Overall, our results showed that lowered expression of PBP and APOB100 proteins served as potential biomarkers of HCOBE, and may play roles in the benzene-induced immunosuppressive effects and disorders in lipid metabolism.

Effect of fungal polysaccharides on the modulation of plasma proteins in streptozotocin-induced diabetic rats

To search out novel biomarkers for monitoring diabetes prognosis, we examined the effect of hypoglycemic fungal exopolysaccharides (EPS) on the differential levels of plasma proteins in streptozotocin-induced diabetic rats. The orally administrated EPS exhibited an excellent hypoglycemic effect, lowering the average plasma glucose level, and increasing insulin secretion in diabetic rats. The 2-DE analysis of rat plasma demonstrated that about 500 visualized spots were differentially regulated, of which 20 spots were identified as principal diabetes-associated proteins. The distinct effect of diabetes induction on the pattern of rat plasma proteins includes the down-regulation of albumin, apolipoprotein E (Apo E), alpha1-inhibitor-3, fetuin beta, Gc-globulin, hemopexin, vitronectin, and transthyretin (TTR) monomer, and the up-regulation of Apo A-I, Apo A-IV, ceruloplasmin, alpha1-antitrypsin, serine protease inhibitor III, and transferrin. Those protein levels were interestingly restored to those of healthy rats by EPS treatment, although the order of magnitude of the changes differed widely. Two proteins of interest showed distinct differential expression with opposite trends: TTR tetramer was significantly down-regulated and immunoglobulin (Ig) kappa light chain was significantly up-regulated upon diabetes induction, both of which were also normalized to those of healthy groups after EPS treatment.

Proteome analysis of human liver carcinoma Huh7 cells harboring hepatitis C virus subgenomic replicon

Chronic infection by hepatitis C virus (HCV) is closely correlated with serious liver diseases. Although considerable progress has been made during recent years, the mechanism of replication and pathogenesis of HCV infection are still elusive. We have applied proteomic techniques in this work to globally analyze the protein expression profiles of a human liver cell lines Huh7 in absence and presence of HCV replication, aiming at elucidating the components of HCV replication and the cellular responses to HCV replication. The protein mixtures of three subcellular fractions from Huh7 and Huh7-HCV were separated by 2-DE under various pH gradients. Differentially expressed spots were identified by MALDI-TOF MS, followed by database searching. A total of 179 comparative proteins were identified unambiguously, including proteins associated with host cytoskeleton, intracellular traffic, oxidative and ER stress, proteasome degradation, translation, apoptosis, proliferation, etc. Host proteins known to interact with HCV proteins, such as HSP27, alpha-actinin, nucleolin and eukaryotic initiation factor 4A-I, were elevated in Huh7-HCV cells. Our study provides the global information of proteomic alteration of Huh7 cells in the presence of HCV replication and the clues for further understanding of the mechanism of HCV replication and pathogenesis.