Research Project
Grant-in-Aid for Scientific Research (B)
ApoE is a major apoprotein of lipoproteins such as VLDL and chiromicron, which is a massive transporter for cholesterol and triglyceride in the circulation. In the CNS apoE secreted by astrocytes also plays important roles in neurite outgrowth, synaptic maintenance and neuronal repair. Although apoE in the CNS is more highly sialylated than plasma apoE, the contribution of O-glycosyl modification with sialic acid residues to the structure and function of apoE is still unknown. To address this, we construct a recombinant adenovirus directing the expression of apoE2, E3, E4 and their mutant forms in order to introduce into glial cells and mcrophages. Expression of apoE and the mutant forms in glial cells and macrophages from apoE-KO mice followed by lectin blot analysis suggested that C-terminal region of apoE contains one major mucin typel O-glycan with sialic acid at Ser290. The interaction of apoE with lipids forms lipoprotein particles, which are subsequently recognized and catabolized by cell-surface lipoprotein receptors. The analysis of knockout mice lacking both of VLDLR and ApoER2 has revealed that VLDLR and ApoER2 function as receptors for reelin, which is involved in the signaling pathway that control neuronal cell positioning. The binding of reelin to the receptors is inhibited by apoE in vitro. To define the function of lipoprotein receptors in lipoprotein metabolism of the CNS, we generated the double KO mice lacking lipoprotein receptors and NPC1, the lack of which is characterized by degeneration of neuronal cells accumulating unesterified cholesterol and sphingolipids in the CNS. An additional defect of NPC1 in VLDLR KO mice led a more severe phenotype in cerebellum development that observed with either alone and other DKO mice, suggesting that defect of NPC1 weakens the function of apoER2 as a reelin receptor.
All 2008 2007 2006 2005
All Journal Article (3 results) (of which Peer Reviewed: 1 results) Presentation (16 results)
Endocrinology 146
Pages: 3286-3294
