Abstract:

Lecithin:retinol acyltransferase (LRAT) is a key enzyme in vitamin A metabolism that helps maintain vitamin A storage, enables vision, and regulates the visual cycle. By converting all-trans-retinol into all-trans-retinyl esters, LRAT supports the regeneration of the visual chromophore in the retinal pigment epithelium and enables the liver to store vitamin A for use throughout the body. Excessive or dysregulated retinoid metabolism can contribute to the accumulation of toxic retinoid byproducts implicated in retinal degenerative diseases such as Stargardt disease and age-related macular degeneration. Although LRAT represents a compelling target for modulating retinoid flux, the chemical tools available to investigate its activity are limited, and the structural determinants governing inhibitor recognition are not completely understood.

My dissertation addresses these gaps through an integrated study investigating the chemical inhibition, structure-function relationships, and therapeutic potential of LRAT.  This work describes the design, synthesis, and biochemical evaluation of a homologous series of retinoid- and apo-carotenal-derived haloacetates and haloacetamides to investigate how polyene length, electrophile reactivity, and terminal linkage identity influence LRAT inhibition.  Inhibitory activity is evaluated using bovine retinal pigment epithelium tissue and purified recombinant truncated LRAT to assess compound potency. Mass spectrometry is employed to characterize inhibitor-induced modifications of LRAT’s catalytic cysteine, providing mechanistic validation of inhibitor-target interactions. These findings establish relationships between chemical structure and inhibitory activity providing a foundation for improved molecular probes to study LRAT function and its therapeutic potential in disorders associated with dysregulated retinoid metabolism.

The outcomes of these investigations expands the chemical tools available for studying LRAT, clarifying the structural features that govern its inhibition, and establishes a foundation for future strategies to modulate retinoid metabolism in health and disease.