Grasp55-/- mice display impaired fat absorption and resistance to high-fat diet-induced obesity.

The Golgi apparatus plays a central role in the intracellular transport of macromolecules. However, molecular mechanisms of Golgi-mediated lipid transport remain poorly understood. Here, we show that genetic inactivation of the Golgi-resident protein GRASP55 in mice reduces whole-body fat mass via impaired intestinal fat absorption and evokes resistance to high-fat diet induced body weight gain. Mechanistic analyses reveal that GRASP55 participates in the Golgi-mediated lipid droplet (LD) targeting of some LD-associated lipases, such as ATGL and MGL, which is required for sustained lipid supply for chylomicron assembly and secretion. Consequently, GRASP55 deficiency leads to reduced chylomicron secretion and abnormally large LD formation in intestinal epithelial cells upon exogenous lipid challenge. Notably, deletion of dGrasp in Drosophila causes similar defects of lipid accumulation in the midgut. These results highlight the importance of the Golgi complex in cellular lipid regulation, which is evolutionary conserved, and uncover potential therapeutic targets for obesity-associated diseases.

Heterosubtypic protective immunity against widely divergent influenza subtypes induced by fusion protein 4sM2 in BALB/c mice.

BACKGROUND: Regular reformulation of currently available vaccines is necessary due to the unpredictable variability of influenza viruses. Therefore, vaccine based on a highly conserved antigen with capability of induction of effective immune responses could be a potential solution. Influenza matrix protein-2 (M2) is highly conserved across influenza subtypes and a promising candidate for a broadly protective influenza vaccine. For the enhancement of broad protection, four tandem copies of consensus M2 gene containing extracellular (ED) and cytoplasmic (CD) without the trans-membrane domain (TM) reconstituted from H1N1, H5N1 and H9N2 influenza viruses were linked and named as 4sM2. The construct was effectively expressed in Escherichia coli, purified and proteins were used to immunize BALB/c mice. Humoral and cell-mediated immune responses were investigated following administration. RESULTS: Mice were intramuscularly immunized with 4sM2 protein 2 times at 2 weeks interval. Two weeks after the last immunization, first humoral and cell mediated immune response specific to sM2 protein were evaluated and the mice were challenged with a lethal dose (10MLD50) of divergent subtypes A/EM/Korea/W149/06(H5N1), A/PR/8/34(H1N1), A/Aquatic bird/Korea/W81/2005(H5N2), A/Aquatic bird/Korea/W44/2005(H7N3), and A/Chicken/Korea/116/2004(H9N2) viruses. The efficacy of 4sM2 was evaluated by determining survival rates, body weights and residual lung viral titers. Our studies demonstrate that the survival of mice immunized with 4sM2 was significantly higher (80-100% survival) than that of unimmunized mice (0% survival). We also examined the long lasting protection against heterosubtype H5N2 virus and found that mice vaccinated with 4sM2 displayed 80% of protection even after 6 months of final vaccination. CONCLUSION: Taken together, these results suggest that prokaryotic expressed multimeric sM2 protein achieved cross protection against lethal infection of divergent influenza subtypes which are lasting for the long time.