Chemokines and their receptor are best known for their role in immune surveillance, where they control the migration and activation of leukocytes to resolve physiological abnormalities such as infection and cancer. However, inappropriate regulation of these proteins is associated with an extraordinary number of pathologies including inflammatory disease, atherosclerosis, cancer and AIDS. Thus there is significant interest in understanding how they function in order to develop drugs to block their activities. In recent years, it has become clear that chemokine-induced cell migration is a complex multistep process involving many different interactions, not only of chemokines with chemokine receptors, but also with glycosaminoglycans (GAGs) and with each other through homo- and hetero-oligomerization. GAGs are structurally diverse linear carbohydrates that are often attached to membrane bound protein anchors as proteoglycans. These interactions are involved in locally sequestering chemokines on cell surfaces, preventing diffusion so that chemokines provide directional cues for migrating cells. Other roles for chemokine:GAG interactions include transport across cells, regulation of oligomerization with as yet poorly characterized signaling consequences, and regulation of receptor binding and activation. Since GAG structures are highly diverse, interactions with chemokines may significantly contribute to the specificity and fine tuning of cell migration, well beyond the chemokine:receptor interaction. However, at present, there is little structural information about chemokine:GAG complexes and their precise functional consequences. An overarching hypothesis of this proposal, is that structural plasticity through oligomerization of chemokines on GAGs, or GAG-induced folding of unstructured domains, are mechanisms of functional specificity/diversity, and that through changes in oligomerization or unfolded state structure, a given chemokine may recognize different GAGs. A second hypothesis is that some chemokines dynamically change their structures through homo- and hetero-oligomerization which may control other steps in cell migration in addition to immobilization on GAGs.
Aim 1 involves structural studies of chemokine:GAG complexes to (i) identify GAGs that preferentially recognize specific chemokines and determine the level of specificity;(ii) characterize binding affinities and interaction mechanisms (e.g. oligomerization or folding of unstructured domains);and (iii) determine trans-scale structural information of complexes from small oligomers through larger oligomeric assemblies on flexible GAGs. To complement these studies, in Aim 2, structural information will be correlated with function to probe how dynamic changes in chemokine oligomerization and GAG interactions coordinate discrete sequential steps of cell migration: (i) transcytosis and cell surface presentation on GAGs, (ii) leukocyte arrest (iii) transmigration, and (iv) activation of cellular defense responses. Together these studies will provide novel insight into the regulation of chemokine function through GAG- binding and oligomerization, where structural plasticity is likely to play a significant role.
Chemokines are involved in controlling cell migration in the context of immune system function and development. However, inappropriate chemokine-mediated cell migration and activation contributes to the pathology of many diseases including asthma, rheumatoid arthritis, multiple sclerosis, heart disease, and cancer. Understanding the molecular details of chemokine:receptor and chemokine:GAG interactions, is and will continue, to lead to the identification of new targets and strategies for disease intervention.
|Zheng, Yi; Han, Gye Won; Abagyan, Ruben et al. (2017) Structure of CC Chemokine Receptor 5 with a Potent Chemokine Antagonist Reveals Mechanisms of Chemokine Recognition and Molecular Mimicry by HIV. Immunity 46:1005-1017.e5|
|Gustavsson, Martin; Zheng, Yi; Handel, Tracy M (2016) Production of Chemokine/Chemokine Receptor Complexes for Structural Biophysical Studies. Methods Enzymol 570:233-60|
|Dyer, Douglas P; Salanga, Catherina L; Johns, Scott C et al. (2016) The Anti-inflammatory Protein TSG-6 Regulates Chemokine Function by Inhibiting Chemokine/Glycosaminoglycan Interactions. J Biol Chem 291:12627-40|
|Fox, Jamie C; Tyler, Robert C; Peterson, Francis C et al. (2016) Examination of Glycosaminoglycan Binding Sites on the XCL1 Dimer. Biochemistry 55:1214-25|
|Dyer, Douglas P; Salanga, Catherina L; Volkman, Brian F et al. (2016) The dependence of chemokine-glycosaminoglycan interactions on chemokine oligomerization. Glycobiology 26:312-26|
|Migliorini, Elisa; Thakar, Dhruv; Kühnle, Jens et al. (2015) Cytokines and growth factors cross-link heparan sulfate. Open Biol 5:|
|Kufareva, Irina; Salanga, Catherina L; Handel, Tracy M (2015) Chemokine and chemokine receptor structure and interactions: implications for therapeutic strategies. Immunol Cell Biol 93:372-83|
|Deshauer, Courtney; Morgan, Ashli M; Ryan, Eathen O et al. (2015) Interactions of the Chemokine CCL5/RANTES with Medium-Sized Chondroitin Sulfate Ligands. Structure 23:1066-77|
|Hanes, Melinda S; Salanga, Catherina L; Chowdry, Arnab B et al. (2015) Dual targeting of the chemokine receptors CXCR4 and ACKR3 with novel engineered chemokines. J Biol Chem 290:22385-97|
|Handel, Tracy Marie (2015) The Structure of a CXCR4:Chemokine Complex. Front Immunol 6:282|
Showing the most recent 10 out of 61 publications