Comparative Proteomic Analysis of Gallbladder Bile Proteins Related to Cholesterol Gallstones

Diancai Zhang,Zhibin Xu,Liying Wang,Jianbin Xiang,Feng Zhou,Xiliang Zha,Duan Cai,Lidong Sun,Antonio Moschetta

doi:10.1371/journal.pone.0054489

Abstract

BackgroundNucleation of cholesterol monohydrate crystals following the aggregation and fusion of cholesterol-enriched vesicles is a critical procedure in the formation of cholesterol gallstone. Biliary proteins play important roles in the process. It is inefficient to screen pro-nucleating or anti-nucleating proteins with routine physiochemical techniques, by which we discovered several pro-nucleating proteins.Methodology/Principal FindingsBased on comparative proteomic technologies, we investigated the differentially expressed proteins between the cholesterol gallstone and control groups, and between the vesicular phase and micellar phase. There are 401±75 spots detected on the cholesterol gallstone group and 389±94 spots on the control group gels, 120±24 spots detected on vesicular phase and 198±37 on micellar phase gels, and accordingly 22 and 8 differentially expressed proteins were identified successfully, respectively. Three of them, HSA, Profilin and Retinol Binding Protein, were validated by Western blot.Conclusion/SignificanceSome of the identified proteins are in good agreement with proteins reported to be involved in the gallstone formation before. The information from this study might provide some important clues to uncover the key proteins involved in the formation of cholesterol gallstone.

Highlights

Gallstone disease is one of the most prevalent gastrointestinal diseases with a substantial burden to health care systems that is supposed to increase in aged populations at risk [1,2,3]
The cholesterol can be dissolved in gallbladder bile mainly due to distinct carriers: mixed micelles consisting of bile salts, phospholipids and cholesterol and vesicles containing phospholipids and cholesterol [6]
Sample Preparation and SDS-PAGE Profiles Gallbladder bile is a complex system mainly composed of water, inorganic ions, conjugated bile salts, phospholipids, cholesterol, bilirubin and proteins

Summary

Introduction

Gallstone disease is one of the most prevalent gastrointestinal diseases with a substantial burden to health care systems that is supposed to increase in aged populations at risk [1,2,3]. Etiology and pathogenesis of cholesterol gallstones are still not well defined, but three mechanisms are of major importance, cholesterol supersaturation, gallbladder hypomotility and kinetic, pro-nucleating or anti-nucleating factors [1,5]. The multifactorial pathogenesis of cholesterol gallstone has been widely accepted, and the relative significance of various factors remains to be clarified. It is widely accepted that nucleated cholesterol originates from cholesterol-enriched vesicles [7]. The characterization of proteins associated with vesicles or mixed micelles in bile is of particular interest, since these might affect the solubility of cholesterol and following the formation of cholesterol gallstone. Nucleation of cholesterol monohydrate crystals following the aggregation and fusion of cholesterol-enriched vesicles is a critical procedure in the formation of cholesterol gallstone. It is inefficient to screen pro-nucleating or anti-nucleating proteins with routine physiochemical techniques, by which we discovered several pro-nucleating proteins

Methods

Results

Conclusion