Indiana University-Purdue University Indianapolis (IUPUI) / The over-accumulation of glycogen appears as a hallmark in various glycogen
storage diseases (GSDs), including Pompe, Cori, Andersen, and Lafora disease. Glycogen
synthase (GS) is the rate-limiting enzyme for glycogen synthesis. Recent evidence suggests
that suppression of glycogen accumulation represents a potential therapeutic approach for
treating these diseases. Herein, we describe the discovery, characterization, and
development of small molecule inhibitors of GS through a multicomponent study including
biochemical, biophysical, and cellular assays. Adopting an affinity-based fluorescence
polarization assay, we identified a substituted imidazole molecule (H23), as a first-in-class
inhibitor of yeast glycogen synthase 2 (yGsy2) from the 50,000 ChemBridge DIVERSet
library. Structural data derived from X-ray crystallography at 2.85 Å, and enzyme kinetic
data, revealed that H23 bound within the uridine diphosphate glucose binding pocket of
yGsy2. Medicinal chemistry efforts examining over 500 H23 analogs produced structure-activity
relationship (SAR) profiles that led to the identification of potent pyrazole and
isoflavone compounds with low micromolar potency against human glycogen synthase 1
(hGYS1). Notably, several of the isoflavones demonstrated cellular efficacy toward
suppressing glycogen accumulation. In an alternative effort to screen inhibitors directly
against human GS, an activity-based assay was designed using a two-step colorimetric
approach. This assay led to the identification of compounds with submicromolar potency
to hGYS1 from a chemical library comprised of 10,000 compounds. One of the hit
molecules, hexachlorophene, was crystallized bound to the active site of yGsy2. The
structure was determined to 3.15 Å. Additional kinetic, mutagenic, and SAR studies
validated the binding of hexachlorophene in the catalytic pocket and its non-competitive
mode of inhibition. In summary, these two novel assays provided feasible biochemical
platforms for large-scale screening of small molecule modulators of GS. The newly-developed,
potent analogs possess diverse promising scaffolds for drug development
efforts targeting GS activity in GSDs associated with excess glycogen accumulation. / 2021-07-01
| Identifer | oai:union.ndltd.org:IUPUI/oai:scholarworks.iupui.edu:1805/23200 |
| Date | 06 1900 |
| Creators | Tang, Buyun |
| Contributors | Hurley, Thomas D., Roach, Peter J., Georgiadis, Millie M., Johnson, Steven M., Elmendorf, Jeffrey S. |
| Source Sets | Indiana University-Purdue University Indianapolis |
| Language | en_US |
| Detected Language | English |
| Type | Dissertation |
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