Proteomic of lipid rafts in the exocrine pancreas from diet-induced obese rats

In the present work, we induced obesity in rats with high-energy-starch diet and studied exocrine pancreas response. The zymogen granule (ZG) or purified plasma membrane (PM) from the exocrine pancreas was used for the isolation of the detergent-resistant membranes (DRMs). Based on high content of cholesterol, GM1, the bile salt dependent lipase (BSDL), and GP2 enrichment, the low-density fractions were defined as lipid rafts. Additionally, the rafts vesicles were determined by immunogold labeling with anti BSDL. By combining MALDI-TOF/MS and nano-LC ESI Q-TOF MS/MS proteomic identification we have selected 33 proteins from the lipid rafts which were classified into at least four functional families. Our data suggest that the acinar PM from the diet-induced obesity rats may be organized into lipid rafts, and characterization of rafts proteome can contribute to improve our understanding of food digestion under obesity. The exocrine pancreas is the major source of enzymes responsible for food digestion in the small intestine and its enzymatic adaptations to the diet composition has been reported [1]. Digestive enzymes in the acinar cells are stored in membrane vesicles called zymogen granules (ZGs). While the ZGs formation has been well-studied, their fusion to the PM and the regulation of digestive enzymes secretion from the apical acinar cells remain poorly understood. Our recent understanding of cell membranes suggest that the PM may be organized into heterogeneous functional microdomains and one of such microdomains known as lipid rafts are enriched in glycosphingolipids/ cholesterol and specific proteins [2]. The lipid rafts have been isolated from several mammalian cells, mostly by their resistance to non-ionic detergent extraction and buoyancy on gradient ultracentrifugation. Studies from our group and others have shown that these methods performed with caution remain to be one of efficient approach to isolate and study the compositions of lipid rafts [3]. It was reported that ZGs and GP2 interact with the lipid raft 0006-291X/$-see front matter Ó