The objective of the proposed research is to undertake a detailed analysis of an underinvestigated class of proteins: the phosphatidylinositol (PtdIns/ phosphatidylcholine (PtdCho) transfer proteins (PITPs). To this end, we will primarily employ the prototypical member of the Sec14-superfamily and its five yeast paralogs as experimental models. Our data indicate that the yeast PITP (Sec14) is an essential factor that operates at the interface of phospholipid metabolism and Golgi/endosomal membrane trafficking functions. The proposed studies will test specific hypotheses that relate to: (i) how the Sec14-like ?nanoreactor? proteins bind and exchange their lipid ligands, (ii) the mechanisms by which non-canonical Sec14-like proteins regulate specific steps of lipid metabolism in yeast, and (iii) how the oxysterol binding protein (OSBP)- related Kes1 works against Sec14-dependent PtdIns-4-phosphate signaling in regulating Golgi/endosomal membrane trafficking and how this lipid binding protein antagonism is played out in control of cell cycle progression through the G1 phase of the cell cycle. These studies will clarify key unanswered questions regarding the mechanism of function of the Sec14 itself, the mechanisms by which Sec14-like proteins couple lipid metabolism to PtdIns kinase signaling, and more global ramifications of PITP functional interactions with the oxysterol binding protein family members (ORPs). The available evidence suggests that PITPs and ORPs play central, and previously unrecognized, roles in lipid-mediated signal transduction processes that interface with such diverse cellular processes as membrane trafficking, basic lipid metabolism and cell cycle. A growing number of inherited neurodegenerative diseases, and diseases of proliferative disorders (e.g. cancer), are attributed to insufficiencies in PITPs and other Sec14-like proteins. Thus, the proposed studies will provide new and fundamental information that bears directly on molecular mechanisms by which PITPs, and Kes1-like OSBPs, regulate and organize signal transduction in eukaryotes and protect mammals from diseases of deranged cell proliferation and neurodegeneration.

Public Health Relevance

Neurodegenerative disorders and cancer are two examples of pathological states where deficiencies in cellular signaling processes result in human disease. The former are a result of premature cell death, while the latter results from inappropriate cell growth. The proposed studies will help define the mechanisms by which lipid signaling pathways are regulated by a novel class of proteins ? the Sec14- like PITPs. Since the pathways to be studied are of direct relevance to neurodegenerative diseases and cancer, it is hoped the new and fundamental information that will derive from these studies will instruct development of new therapies for these disorders.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM044530-27
Application #
9613820
Study Section
Membrane Biology and Protein Processing Study Section (MBPP)
Program Officer
Flicker, Paula F
Project Start
1991-07-01
Project End
2020-12-31
Budget Start
2019-01-01
Budget End
2019-12-31
Support Year
27
Fiscal Year
2019
Total Cost
Indirect Cost
Name
Texas A&M University
Department
Other Basic Sciences
Type
Schools of Medicine
DUNS #
835607441
City
College Station
State
TX
Country
United States
Zip Code
77845
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