Sphingolipids are key mediators and regulators of cell signaling pathways. Our studies have focused on the actions of two classes of sphingolipids represented by glycosphingolipids (GSLs) and sphingosine-1-phosphate (S1P). Our work is aimed at defining the normal functions of these sphingolipids and understanding their roles in disease processes. GSLs are found in the outer leaflet of the plasma membrane and are concentrated in specialized signaling structures. They are particularly abundant in neuronal cells in the form of gangliosides (sialic acid containing GSLs). Through genetic disruption of genes that encode synthetic enzymes for GSLs, we have created a series of mice that express limited glycosphingolipid structures. We are using these mice to discover the functions of GSLs. When the cellular machinery responsible for GSL degradation is defective, GSL storage diseases result in which profound neurodegeneration occurs. Examples are Tay-Sachs, Sandhoff and Gaucher diseases. S1P is a signaling molecule that is crucial for the regulation of several diverse cellular events, including cell survival, growth, differentiation and calcium mobilization. Recently, numerous studies on S1P have demonstrated its importance in the development of the cardiovascular system and immunity through a family of G protein-coupled receptors (GPCRs), designated S1P1-5. 1. We have shown that S1P also plays a key role in neural development, probably mediated by the S1P1 receptor. We found that simultaneous disruption of the two known sphingosine kinase genes in mice results in a deficiency of S1P, which disturbed angiogenesis and caused neural tube closure defects, followed by embryonic lethality. Dramatic increases in apoptosis and decreases in mitosis were seen in the developing nervous systems of these mutant embryos. Thus, S1P joins a growing list of signaling molecules, such as vascular endothelial growth factor, which regulate the functionally intertwined pathways of angiogenesis and neurogenesis. Our findings not only provide new biological insights into S1P signaling, but also suggest that exploitation of this pathway could lead to the development of novel therapeutic approaches for neurological disease. 2. We have now established a Ugcg allele in mice flanked by loxP sites (floxed). When cre recombinase was expressed in the nervous system under the Nestin promoter, the floxed gene underwent recombination, resulting in a substantial reduction of Ugcg expression and of glycosphingolipid ganglio-series levels. The mice lacking Ugcg in the nervous system show a striking loss of Purkinje cells and abnormal neurologic behavior. The floxed Ugcg allele will facilitate the analysis of the function of glycosphingolipids in normal physiology and in diseases such as diabetes and cancer.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Intramural Research (Z01)
Project #
1Z01DK056000-07
Application #
7153394
Study Section
(GDDB)
Project Start
Project End
Budget Start
Budget End
Support Year
7
Fiscal Year
2005
Total Cost
Indirect Cost
Name
U.S. National Inst Diabetes/Digst/Kidney
Department
Type
DUNS #
City
State
Country
United States
Zip Code
Olivera, Ana; Urtz, Nicole; Mizugishi, Kiyomi et al. (2006) IgE-dependent activation of sphingosine kinases 1 and 2 and secretion of sphingosine 1-phosphate requires Fyn kinase and contributes to mast cell responses. J Biol Chem 281:2515-25
Venkataraman, Krishnan; Thangada, Shobha; Michaud, Jason et al. (2006) Extracellular export of sphingosine kinase-1a contributes to the vascular S1P gradient. Biochem J 397:461-71
Michaud, Jason; Kohno, Masataka; Proia, Richard L et al. (2006) Normal acute and chronic inflammatory responses in sphingosine kinase 1 knockout mice. FEBS Lett 580:4607-12
Kohno, Masataka; Momoi, Michiko; Oo, Myat Lin et al. (2006) Intracellular role for sphingosine kinase 1 in intestinal adenoma cell proliferation. Mol Cell Biol 26:7211-23
Kono, Mari; Dreier, Jennifer L; Ellis, Jessica M et al. (2006) Neutral ceramidase encoded by the Asah2 gene is essential for the intestinal degradation of sphingolipids. J Biol Chem 281:7324-31
Lo, Charles G; Xu, Ying; Proia, Richard L et al. (2005) Cyclical modulation of sphingosine-1-phosphate receptor 1 surface expression during lymphocyte recirculation and relationship to lymphoid organ transit. J Exp Med 201:291-301
Osawa, Yosuke; Hannun, Yusuf A; Proia, Richard L et al. (2005) Roles of AKT and sphingosine kinase in the antiapoptotic effects of bile duct ligation in mouse liver. Hepatology 42:1320-8
Wu, Yun-Ping; Mizukami, Hiroki; Matsuda, Junko et al. (2005) Apoptosis accompanied by up-regulation of TNF-alpha death pathway genes in the brain of Niemann-Pick type C disease. Mol Genet Metab 84:9-17
Sandhoff, Roger; Geyer, Rudolf; Jennemann, Richard et al. (2005) Novel class of glycosphingolipids involved in male fertility. J Biol Chem 280:27310-8
Fujitani, Masashi; Kawai, Hiromichi; Proia, Richard L et al. (2005) Binding of soluble myelin-associated glycoprotein to specific gangliosides induces the association of p75NTR to lipid rafts and signal transduction. J Neurochem 94:15-21

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