Although originally considered mysterious and 'sphinx-like', glycosphingolipids (GSLs) and related sphingolipid (SL) metabolites have emerged as key bioactive signaling molecules and organizers of membrane micro- domains, playing vital roles in normal (cell development, differentiation, apoptosis, autophagy) and pathogenic membrane-related processes (bacterial &viral infections, oncogenesis, genetic lipid storage diseases). However, critical issues persist regarding exactly how lipid compositional changes involving both SLs and non- SL lipids: i) alter the membrane physical environment;ii) control SL lateral organization and surface accessi- bility;iii) regulate the translocation and functionality of peripheral, amphitropic membrane proteins with affinity for SLs. Our goal is to address these key issues by defining the functional regulation of a novel lipid transfer protein family that selectively transfers SLs between membranes using a unique lipid-binding conformational fold (GLTP-fold) and a new membrane interaction motif for peripheral, amphitropic proteins. The objective of this renewal application, which builds on our progress and exciting new Prelim. Data, is to move the field forward by accomplishing the following Aims: 1) Map Key Regions of GLTP-folds that Control Selectivity for Different Types of Sphingolipids;2) Characterize Novel Membrane Interaction Motif of GLTP-folds;3) Determine How Lipid-Sphingolipid Lateral Packing Interactions within Membranes Regulate GLTP-fold Action;4) Determine How Human GLTP Up-Regulation Induces Cell Death Processes. We are particularly well prepared to undertake the proposed research because we achieved the first successful cloning of GLTP as well as the first three-dimensional structure of GLTP, establishing the GLTP-fold as unique among lipid binding/transfer proteins, as the prototype for the new GLTP superfamily, and as having a novel membrane interaction domain among peripheral amphitropic proteins. We also have developed the means to quantita- tively assess lateral elastic interactions of GSLs with each other and with other membrane lipids while achieving nanoscale resolution into lipid lateral mixing, enabling fundamental insights into the structural features of sphingolipids that control interaction with GLTP. Because of our progress, the complementary expertise within our research team, and the historic success of our collaborators, the total research environment is especially conducive for achieving the new aims proposed herein. It is our expectation that our new discovery of a human GLTP-fold that binds/transfers ceramide-1-phosphate will not only strongly under- score the importance of GLTP-folds in human cells, but that the new knowledge will have the added significant outcome of enabling production of 'designer GLTP-folds'with highly focused selectivity for specific glycolipid/sphingolipid types by point mutation. This new knowledge is expected to provide a foundation for biotechnological use of the GLTP-fold in exciting and innovative ways, such as introducing specific GSL antigens into cells to help achieve targeted destruction of diseased cells via immunotherapeutic means.

Public Health Relevance

The new knowledge gained by the research proposed herein is expected to provide the foundation for using glycolipid transfer proteins in new and innovative ways, such as introducing specific GSL antigens into cancer cells to help achieve targeted destruction of diseased cells via immunotherapeutic as well as for triggering self- destruction of diseased cells by programmed cell death processes.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM045928-19
Application #
8309152
Study Section
Biochemistry and Biophysics of Membranes Study Section (BBM)
Program Officer
Chin, Jean
Project Start
1992-05-01
Project End
2015-06-30
Budget Start
2012-07-01
Budget End
2013-06-30
Support Year
19
Fiscal Year
2012
Total Cost
$381,250
Indirect Cost
$131,250
Name
University of Minnesota Twin Cities
Department
None
Type
Organized Research Units
DUNS #
555917996
City
Minneapolis
State
MN
Country
United States
Zip Code
55455
Zhai, Xiuhong; Boldyrev, Ivan A; Mizuno, Nancy K et al. (2014) Nanoscale packing differences in sphingomyelin and phosphatidylcholine revealed by BODIPY fluorescence in monolayers: physiological implications. Langmuir 30:3154-64
Simanshu, Dhirendra K; Zhai, Xiuhong; Munch, David et al. (2014) Arabidopsis accelerated cell death 11, ACD11, is a ceramide-1-phosphate transfer protein and intermediary regulator of phytoceramide levels. Cell Rep 6:388-99
Samygina, Valeria R; Ochoa-Lizarralde, Borja; Popov, Alexander N et al. (2013) Structural insights into lipid-dependent reversible dimerization of human GLTP. Acta Crystallogr D Biol Crystallogr 69:603-16
Simanshu, Dhirendra K; Kamlekar, Ravi Kanth; Wijesinghe, Dayanjan S et al. (2013) Non-vesicular trafficking by a ceramide-1-phosphate transfer protein regulates eicosanoids. Nature 500:463-7
Zhai, Xiuhong; Momsen, William E; Malakhov, Dmitry A et al. (2013) GLTP-fold interaction with planar phosphatidylcholine surfaces is synergistically stimulated by phosphatidic acid and phosphatidylethanolamine. J Lipid Res 54:1103-13
Kamlekar, Ravi Kanth; Simanshu, Dhirendra K; Gao, Yong-guang et al. (2013) The glycolipid transfer protein (GLTP) domain of phosphoinositol 4-phosphate adaptor protein-2 (FAPP2): structure drives preference for simple neutral glycosphingolipids. Biochim Biophys Acta 1831:417-27
Gao, Yongguang; Chung, Taeowan; Zou, Xianqiong et al. (2011) Human glycolipid transfer protein (GLTP) expression modulates cell shape. PLoS One 6:e19990
Kenoth, Roopa; Kamlekar, Ravi Kanth; Simanshu, Dhirendra K et al. (2011) Conformational folding and stability of the HET-C2 glycolipid transfer protein fold: does a molten globule-like state regulate activity? Biochemistry 50:5163-71
Samygina, Valeria R; Popov, Alexander N; Cabo-Bilbao, Aintzane et al. (2011) Enhanced selectivity for sulfatide by engineered human glycolipid transfer protein. Structure 19:1644-54
Kamlekar, Ravi Kanth; Gao, Yongguang; Kenoth, Roopa et al. (2010) Human GLTP: Three distinct functions for the three tryptophans in a novel peripheral amphitropic fold. Biophys J 99:2626-35

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