Yeast and mammalian two-hybrid systems for studying protein-protein interactions. Blood Coagul Fibrinolysis. 2007;383:215-225. [PMID: 18217688 DOI: 10.1097/MBC.0b013e3282f9b17f]

Impact of sustained virus elimination on natural anticoagulant activity in patients with chronic viral hepatitis C

Previous studies have reported reduced synthesis of various hemostatic factors in patients with chronic liver disease. Whether changes in plasma levels of these proteins reflect recovered liver synthetic function following virological eradication therapy has not been approved yet. The aim of the study was to determine the impact of sustained viral suppression achieved with pegylated interferon alpha and ribavirin on hemostatic parameters including natural anticoagulants in patients with chronic hepatitis C. The following coagulation screening tests were obtained in thirty patients with chronic viral hepatitis C before and after completion of antiviral treatment: activated partial thromboplastin time, prothrombin time, plasma fibrinogen and natural anticoagulant proteins antithrombin III, protein C (PC) and total protein S (PS) activity. Only patients who achieved durable virus suppression were included. The mean PC and PS levels were significantly lower in patients with chronic viral hepatitis C before antiviral therapy than in healthy controls (79.04 ± 16.19 % vs. 109.92 ± 21.33% and 54.04 ± 16.11% vs. 87.60 ± 8.15%, respectively; (p<0.001). Mean levels of PC exhibited a significant increase by 14.69 % after the completion of antiviral treatment (93.73 ± 14.18%, p<0.001) as well as PS levels, which significantly increased by 21.46% (75.50 ± 15.43, p<0.001) when compared with pre-treatment values. No remarkable fluctuations in other hemostatic parameters were noted. Protein C and protein S are sensitive markers of hepatocyte synthetic impairment and are valuable markers in monitoring the efficacy of antiviral treatment in chronic hepatitis C patients. Larger studies are needed to confirm our results.

Effects of Pegylated Interferon α on Fibrinolytic Parameters in Patients With Chronic Hepatitis C

Interferon (IFN) interacts with endothelial cells and modulates the functions of these cells. In our study, we aimed to determine the effects of treatment with pegylated IFN-α (peg-IFN-α) on fibrinolytic parameters in patients with chronic hepatitis C. Fifteen patients with chronic hepatitis C were treated with peg-IFN-α once per week plus daily oral ribavirin. Euglobulin lysis time (ELT), plasma levels of d-dimer, tissue-type plasminogen activator (t-PA), plasminogen activator inhibitor 1 (PAI-1), and thrombin activatable fibrinolysis inhibitor (TAFI) were determined before treatment, 2 weeks, 1 month, and 3 months after the initiation of the treatment. Plasma levels of t-PA increased significantly 1 month and 3 months after the treatment ( P < .05). The PAI-1 and TAFI levels in 2 weeks, 1 month and 3 months after treatment were not statistically different as compared with pretreatment levels ( P > .05) No significant difference in plasma d-dimer levels was observed during peg-IFN-α treatment ( P > .05). There was a significant decrease in ELT 1 month and 3 months after the treatment ( P < .05). Our results indicated that treatment with peg-IFN-α may be associated with enhanced fibrinolysis,

Interaction between fibrinogen alpha chain and the whole S protein of hepatitis B virus

AIM: To screen the proteins interacting with the whole S protein of hepatitis B virus (HBV) from hepatocyte cDNA library by yeast two-hybrid system, and to validate interacting behavior between fibrinogen alpha chain and the whole S protein by reverse yeast two-hybrid.

METHODS: The whole S gene of HBV was cloned into yeast expression vector pDEST32 to construct a bait plasmid, which was verified by Western blot. The bait plasmid and prey plasmids inserted liver cDNA fragments were cotransformed into yeast cells MaV203 by Liac-mediated transformation. Diploid yeasts were plated on synthetic dropout nutrient medium to screen positive colonies. After extracting and sequencing of prey plasmids from positive colonies, the inserted sequences were bioinformatically analyzed. For reverse yeast two-hybrid, the bait plasmid expressing partial fibrinogen alpha chain and four prey plasmids expressing the whole S protein mutants were re-combined. The reconstituted bait plasmid was cotransformed into yeast cells MaV203 with the four prey plasmids, respectively. Diploid yeasts were plated on synthetic dropout nutrient medium and X-gal assay was performed to validate the interacting behavior.

RESULTS: By yeast two-hybrid technique, prey plasmids that were inserted partial gene coding 266-644 amino acid of fibrinogen alpha chain had a positive reaction with bait plasmid coding the whole S protein of HBV. By reverse yeast two-hybrid, fibrinogen alpha chain protein interacted with the four whole S protein mutants. The protein binding domain of the whole S protein might be the leading 268 amino acids.

CONCLUSION: Fibrinogen alpha chain protein may bind the whole S protein of HBV. The interacting domain is in the 266-644 amino acids of fibrinogen alpha chain and the frontal 268 amino acids of the whole S protein, respectively.