Date

2018

Department or Program

Biological Sciences

Primary Wellesley Thesis Advisor

Louise E.O. Darling

Abstract

Regulation of the heart’s rhythm is achieved by the propagation of currents through membrane-localized cardiac ion channels, dysfunction of which can lead to potentially deadly arrhythmias or cardiac arrest. Indeed, mutations in the genes encoding potassium channel alpha subunit proteins hERG and KVLQT1, responsible for producing the pore-forming subunits that carry the delayed rectifier currents IKr and IKs respectively, have been found to underlie the majority of Long QT syndrome cases. hERG and KVLQT1 have been previously shown to undergo dynamic physical interactions, and the two currents exhibit mutual functional downregulation in cells from both transgenic animal models and heterologous cell lines. These interactions are abrogated by cAMP, although cAMP does not directly bind either protein; rather, PKA-mediated phosphorylation is hypothesized to be responsible for regulation of these interactions. Nonetheless, the precise mechanisms regulating hERG-KVLQT1 interactions, as well as their subcellular localization, remain to be elucidated. As such, there is considerable interest in assessing the role of the cAMP/PKA pathway in the trafficking and membrane localization of hERG and KVLQT1. In implementing a biotinylation-based surface protein assay for purification of membrane-localized proteins, we semi-quantified surface expression levels of hERG and KVLQT1 and thus determined the roles played by hERG-KVLQT1 interactions and cAMP in plasma membrane expression of these alpha subunit proteins. Characterizing the endogenous mechanisms regulating hERG and KVLQT1 trafficking has broad clinical implications and may lead to improved therapies.

Available for download on Saturday, May 20, 2023

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