Date of Award

Spring 2023

Document Type

Restricted Thesis

Terms of Use

© 2023 Quynn C. Hotan. All rights reserved. Access to this work is restricted to users within the Swarthmore College network and may only be used for non-commercial, educational, and research purposes. Sharing with users outside of the Swarthmore College network is expressly prohibited. For all other uses, including reproduction and distribution, please contact the copyright holder.

Degree Name

Bachelor of Arts

Department

Chemistry & Biochemistry

First Advisor

Daniela Fera

Abstract

The mitogen-activated protein kinase (MAPK), otherwise known as the ERK, pathway is a signal transduction pathway known to be critical for the regulation of cellular proliferation, differentiation, and apoptosis, among other cellular processes. This pathway consists of several key proteins: Ras, Raf, MEK, and ERK. Aberrant activation of the ERK pathway is often linked to uncontrolled cell growth and is implicated in carcinogenesis. Inhibitors of Raf and MEK have previously shown potential in negating the detrimental effects of MAPK upregulation; however, these inhibitors are limited by the incurrence of resistance. In an effort to overcome drug resistance, recent efforts have turned towards targeting novel protein-protein interactions and developing combination therapies. Thus, understanding interactions between downstream targets of the MEK pathway, MEK and ERK, will provide additional insights into the therapeutic implications of the ERK pathway. Currently, a structure of the MEK-ERK complex has yet to be solved which limits efforts to design inhibitors targeting the MEK-ERK interface.

Previous studies conducted on MEK-ERK interactions have largely focused on their protein-protein interactions near the activation loop due to the nature of MEK’s function as a kinase that phosphorylates ERK. However, evidence suggests that MEK and ERK can also interact at another region on the opposite face of the activation loop known as the MEK-ERK docking site. To identify important residues for MEK-ERK docking site interactions, we mutated MEK and ERK residues near the MEK-ERK docking site using MEK1 and ERK2 constructs. Circular dichroism, biolayer interferometry, co-elutions and phosphorylation assays were performed to determine the effects of the mutations on protein folding, binding, complexation, and activity, respectively. Several MEK and ERK mutants tested showed altered binding and activity compared to wildtype. Further characterization of this region will generate additional insight into MEK-ERK interactions and provide a structural basis to current design efforts for MEK-ERK inhibitors.

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