GSBS Dissertations and Theses

ORCID ID

0000-0003-3931-5555

Approval Date

12-21-2017

Document Type

Doctoral Dissertation

Academic Program

Biochemistry and Molecular Pharmacology

Department

Biochemistry and Molecular Pharmacology

First Thesis Advisor

Anthony Carruthers

Keywords

glucose transport, membrane transport, molecular docking, competitive inhibition, facilitated diffusion, ligand binding, GLUT1 inhibition, membrane transport protein, WZB117, BAY-876, dietary flavonoids

Abstract

The glucose transport protein, GLUT1, is highly expressed in rapidly proliferating cells, including cancer cells, while decreased GLUT1 levels are found in diseases such as GLUT1 deficiency syndrome and Alzheimer’s. There is increased interest in developing GLUT1 inhibitors as novel anticancer therapeutics, and the discovery of compounds that directly stimulate GLUT1 function. This work investigates how small molecules stimulate and/or inhibit GLUT1-mediated glucose transport, either directly or through the AMPK pathway.

Using sugar transport assays and docking analyses to explore Ligand–GLUT1 interactions and specificity of binding, we show that: 1) Ligands inhibit GLUT1 by competing with glucose for binding to the exofacial or endofacial sugar binding sites; 2) Subsaturating inhibitor concentrations stimulate sugar uptake; 3) Ligands inhibit GLUT1–, GLUT3– and GLUT4–mediated sugar uptake in HEK293 cells; and 4) Inclusion of a benzonitrile head group on endofacial GLUT1 inhibitors confers greater inhibitory potency.

Furthermore, we investigated AMPK-regulated GLUT1 trafficking in cultured blood-brain barrier endothelial cells, and show that inhibition of GLUT1 internalization is not responsible for increased cell surface levels of GLUT1 observed with AMPK activation in these cells.

This study provides a framework for screening candidate GLUT1 inhibitors for specificity, and for optimizing drug design and delivery. Our data on transport stimulation at low inhibitor concentrations support the idea that GLUT1 functions as a cooperative oligomer of allosteric alternating access subunits.

DOI

10.13028/M2R69F

Rights and Permissions

Licensed under a Creative Commons license

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution-Noncommercial 4.0 License

Available for download on Saturday, January 26, 2019

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