The interleukin-7 (IL-7) signaling pathway plays essential roles in modeling the extracellular matrix and the development and homeostasis of B and T cells. Aberrant IL-7 signaling has been implicated in severe combined immunodeficiency, autoimmune conditions, and cancers. The IL-7 signal is triggered when soluble IL-7 interacts with two cell surface cytokine receptors, interleukin-7 receptor (IL-7R) and the common gamma- chain. In the previous funding period, we determined the structural, energetic, and cell biological features of the interaction of IL-7 with IL-7R. In this funding period, we will dissect the moleculr mechanisms of the interactions of IL-7 with glycosaminoglycans (e.g. heparin/heparin sulfate) and the common gamma-chain receptor with IL-7 and IL-7R. Preliminary studies of these interactions reveal the formation of unexpected non- activating complexes, either unique to IL-7 signaling or unidentified for the other common gamma-chain family members. Specifically, glycosaminoglycan binding induces dimer formation of IL-7, and common gamma- chain receptor can bind to IL-7 independent of IL-7R and to IL-7R independent of IL-7. Further studies will include three-dimensional x-ray crystallographic structures of the non-activating IL-7/GAG, IL-7/common gamma-chain, IL-7R/common gamma-chain complexes, as well as the activating IL-7/IL-7R/common gamma- chain ternary complex. The binding determinants of these epitopes also will be determined using site-directed scanning mutagenesis and various biophysical methods, including isothermal titration calorimetry and surface plasmon resonance. The structural and biophysical studies of non-activating and activating complexes ultimately will be used to develop models that explain normal and aberrant IL-7 signaling mechanisms and generate novel protein reagents and therapeutics that treat the numerous diseases associated with impaired IL-7 signaling.

Public Health Relevance

This research proposal focuses on dissecting the structural, biophysical, and functional mechanisms of glycosaminoglycans and the common gamma-chain cytokine receptor in the IL-7 signaling pathway and the development of novel interleukin-7 variants to enhance or suppress this critical signaling pathway.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
High Priority, Short Term Project Award (R56)
Project #
2R56AI072142-08A1
Application #
8727130
Study Section
Cellular and Molecular Immunology - A Study Section (CMIA)
Program Officer
Leitner, Wolfgang W
Project Start
2006-12-01
Project End
2014-08-31
Budget Start
2013-09-03
Budget End
2014-08-31
Support Year
8
Fiscal Year
2013
Total Cost
$357,200
Indirect Cost
$122,200
Name
University of Maryland College Park
Department
Miscellaneous
Type
Other Domestic Higher Education
DUNS #
790934285
City
College Park
State
MD
Country
United States
Zip Code
20742