Single molecule imaging of the initial steps of EGFR activation in Mammalian cells

Abstract: The epidermal growth factor receptor (EGFR) is a receptor tyrosine kinase that undergoes ligand mediated dimerization and activation. EGFRs regulate physiological processes such as cell migration, differentiation and proliferation, but their aberrant activation plays a pivotal role in cancer and neurodegenerative disease development. In resting cells, EGFRs are present as a population of inactive monomers and predimers that are laterally mobile and expressed uniformly across the cell surface. Ligand binding rapidly shifts the inactive monomer population to receptor dimers. Besides an increase in dimers, clusters of immobile EGF receptors have been observed shortly after activation. It remains unclear however, to what extent dimerization and clustering depend on one another, their role in receptor phosphorylation, and the intracellular proteins and endocytic compartments involved in facilitating their formation.

In the present work, the current model for EGFR activation is extended to include the role of EGFR predimers and clusters in receptor signaling. With a highly efficient fluorescent protein labeling approach, we image and track the majority of GFP-labeled EGF receptors at the plasma membrane of a living cell on a single molecule (SM) level. The focus on SM imaging of dynamic EGFR interactions affords in addition to determining diffusion coefficients of receptors, the quantification of their aggregation behavior in real time. The direct observation of EGFR interactions along with the use of several EGFR mutations and pharmacological inhibitors have led to three core findings in this work; (i) EGFR diffusion on the plasma membrane is tightly linked to its activation, where activated receptors have lower diffusion coefficients than unliganded receptors, (ii) EGF induced redistribution of EGFRs into clusters requires an active kinase domain and receptor clustering is non-essential for short-term receptor activation, and (iii) endocytic adaptor proteins provide a scaffold facilitating ligand-induced EGFR clustering. Ultimately, a better understanding of EGFR activation can aid the development of pharmacological targets for down-regulating aberrant EGFR activation

Object Details

• Location: Deutsche Nationalbibliothek Frankfurt am Main
• Extent: Online-Ressource
• Language: Englisch
• Notes: Universität Freiburg, Dissertation, 2017

Classification and Topics

• Classification: Biowissenschaften, Biologie

Contributors, Places and Time

• Event: Veröffentlichung
• (where): Freiburg
• (who): Universität
• (when): 2017
• Creator: Tahvildar Khazaneh, Shima
• Contributor: Ulbrich, Maximilian ; Weber, Wilfried ; Albert-Ludwigs-Universität Freiburg. Fakultät für Biologie ; Albert-Ludwigs-Universität Freiburg. Centre for Biological Signalling Studies ; Albert-Ludwigs-Universität Freiburg. Fakultät für Biologie

Further information

• DOI: 10.6094/UNIFR/12692
• URN: urn:nbn:de:bsz:25-freidok-126929
• Rights: Kein Open Access; Der Zugriff auf das Objekt ist unbeschränkt möglich.
• Last update: 25.03.2025, 1:42 PM CET