The apical sodium-dependent bile acid transporter (ASBT) plays a key role in the enterohepatic recycling of bile salts, cholesterol homeostasis, and serves as a molecular target for hypercholesterolemic agents. Although the transporter sequence is known, there is controversy about its membrane topology and very little is known about ASBT structure-function and ligand binding domains. The proposed research will focus on the structural biology of ASBT. Using a novel approach that combines molecular and computational biology our long-term goal is to delineate the three-dimensional structure, ligand-binding domains, and cellular transport mechanism of ASBT. The following specific aims will be addressed: (1) define the membrane topology of ASBT using a series of topology scanning approaches; (2) Construct a comprehensive structural and predictive model of ASBT that can correlate structural point mutations to changes in ligand affinity and transport; (3) Define the functional regions of ASBT by site-directed mutagenesis; we have developed a computer-assisted site-directed mutagenesis approach to probe ASBT protein for amino acid residues implicated in ligand and sodium interactions; (4) Determine the ligand binding domains of ASBT by mass spectrometry; we will employ selective photoaffinity labels to determine ligand-binding peptide sequences. Information gained by these studies will significantly increase our understanding of the structural interactions that drive bile acid transport and further our structural knowledge of solute carrier proteins in general. Additionally, it may aid future development of specific therapeutic strategies against hypercholesterolemia and related cardiovascular diseases.

Agency
National Institute of Health (NIH)
Institute
National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK)
Type
Research Project (R01)
Project #
5R01DK061425-04
Application #
7046704
Study Section
Pharmacology A Study Section (PHRA)
Program Officer
Serrano, Jose
Project Start
2003-05-01
Project End
2008-02-29
Budget Start
2006-03-01
Budget End
2007-02-28
Support Year
4
Fiscal Year
2006
Total Cost
$238,541
Indirect Cost
Name
University of Maryland Baltimore
Department
Pharmacology
Type
Schools of Pharmacy
DUNS #
188435911
City
Baltimore
State
MD
Country
United States
Zip Code
21201
Chothe, Paresh P; Czuba, Lindsay C; Moore, Robyn H et al. (2018) Human bile acid transporter ASBT (SLC10A2) forms functional non-covalent homodimers and higher order oligomers. Biochim Biophys Acta Biomembr 1860:645-653
Czuba, Lindsay C; Hillgren, Kathleen M; Swaan, Peter W (2018) Post-translational modifications of transporters. Pharmacol Ther 192:88-99
Shiffka, Stephanie J; Kane, Maureen A; Swaan, Peter W (2017) Planar bile acids in health and disease. Biochim Biophys Acta Biomembr 1859:2269-2276
Welch, Matthew A; Köck, Kathleen; Urban, Thomas J et al. (2015) Toward predicting drug-induced liver injury: parallel computational approaches to identify multidrug resistance protein 4 and bile salt export pump inhibitors. Drug Metab Dispos 43:725-34
Lynch, Caitlin; Pan, Yongmei; Li, Linhao et al. (2014) Activation of the constitutive androstane receptor inhibits gluconeogenesis without affecting lipogenesis or fatty acid synthesis in human hepatocytes. Toxicol Appl Pharmacol 279:33-42
Moore, Robyn H; Chothe, Paresh; Swaan, Peter W (2013) Transmembrane domain V plays a stabilizing role in the function of human bile acid transporter SLC10A2. Biochemistry 52:5117-24
Lynch, Caitlin; Pan, Yongmei; Li, Linhao et al. (2013) Identification of novel activators of constitutive androstane receptor from FDA-approved drugs by integrated computational and biological approaches. Pharm Res 30:489-501
Sabit, Hairat; Mallajosyula, Sairam S; MacKerell Jr, Alexander D et al. (2013) Transmembrane domain II of the human bile acid transporter SLC10A2 coordinates sodium translocation. J Biol Chem 288:32394-404
Claro da Silva, Tatiana; Polli, James E; Swaan, Peter W (2013) The solute carrier family 10 (SLC10): beyond bile acid transport. Mol Aspects Med 34:252-69
González, Pablo M; Hussainzada, Naissan; Swaan, Peter W et al. (2012) Putative irreversible inhibitors of the human sodium-dependent bile acid transporter (hASBT; SLC10A2) support the role of transmembrane domain 7 in substrate binding/translocation. Pharm Res 29:1821-31

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