Dissertation
The mechanism of interleukin-5 receptor assembly and activation as determined by fluorescence resonance energy transfer imaging
Doctor of Philosophy (Ph.D.), Drexel University
Aug 2008
DOI:
https://doi.org/10.17918/00007962
Abstract
The hematopoietic cytokine Interleukin-5 (IL-5) orchestrates its functions through binding to a cell surface receptor complex consisting of two transmembrane subunits, a specific ligand binding [alpha] subunit and a signal transducing [beta]c subunit that is shared between IL-3, IL-5, and GM-CSF. The assembly mechanism of the receptor that leads to activation is flot fully understood. In this thesis, fluorescence resonance energy transfer (FRET) imaging is used as a technique to clarify the details of receptor organization and to characterize the physical interactions between IL-5 and its cognate full length receptor subunits within the context of an intact membrane. We find that [beta]c is a preformed homo-oligomer that undergoes hetero-oligomerization and/or further conformational changes upon the binding of IL-5. Additionally, at least two a subunits are present in IL-5· IL-5R[alpha]· [beta]c complexes upon activation. We also find that an intact hetero-oligomeric complex is required to recruit the new [alpha]-chain(s) to the receptor complex. The IL-5 induced recruitment of a new a subunit(s) to the high affinity complex may provide a means of mediating the final intracellular receptor signals. Together these findings support the sequential assembly model of IL-5 receptor activation whereby IL-5 triggers cellular responses by binding first to the specific [alpha] receptor, followed by binding of the ligand-specific a complex to [beta]c; this then leads to conformational changes and/or higher order oligomerization formation of [alpha] and [beta]c. These studies uniquely contribute to the current understanding of the molecular interactions of the IL-5 ligand-receptor system during receptor assembly and activation by presenting new evidence of the intracellular rearrangements of the full length receptor in an intact cellular environment and in response to ligand-binding. These results can help elucidate the structural basis of signal specificity and amplification utilized by Class I cytokine receptors, and may eventually lead to novel therapeutic interventions in pathophysiological signaling by these cytokines.
Metrics
24 File views/ downloads
18 Record Views
Details
- Title
- The mechanism of interleukin-5 receptor assembly and activation as determined by fluorescence resonance energy transfer imaging
- Creators
- Meirav Zaks-Zilberman
- Contributors
- Irwin Chaiken (Advisor) - Drexel University, Drexel University (1970-)Bradford Aldrich Jameson (Advisor) - Drexel University, Drexel University (1970-)
- Awarding Institution
- Drexel University
- Degree Awarded
- Doctor of Philosophy (Ph.D.)
- Publisher
- Drexel University; Philadelphia, Pennsylvania
- Number of pages
- ix, 120 pages, 29 unnumbered pages
- Resource Type
- Dissertation
- Language
- English
- Academic Unit
- Biochemistry and Molecular Biology; College of Medicine; Drexel University
- Other Identifier
- 991021888822204721