Department of Biological Chemistry & Molecular Pharmacology
tel: (617) 713-8200; fax: (617) 713-8232
Adhesion Receptors of the Immune System
Integrins are the most sophisticated adhesion molecules known. Like many surface molecules, integrins can transmit signals into cells. However, integrins also transmit "inside-out signals." Other receptors transmit signals that impinge on the cytoplasmic and transmembrane domains of integrins. In less than a second, these signals are transmitted to integrin extracellular domains, which undergo conformational movements that enable ligand binding. Thus, integrins can rapidly stabilize contacts between lymphocytes and antigen-presenting cells, and between leukocytes in the bloodstream and endothelium at sites of inflammation. Integrins also mediate cell migration within the body, which involves highly regulated interactions with the actin cytoskeleton and extracellular ligands.
We are developing a three-dimensional picture of integrins and their ligands, to understand how they bind to one another, the moving parts of the integrin machines and how they are linked together, and the connections to other signaling molecules.
The lab also focuses on selectins and a4 integrins that have a unique function in the vasculature. Their receptor-ligand interactions mediate rolling of leukocytes on endothelium, an adhesive modality that enables surveillance for signs of inflammation. We are characterizing the molecular and cellular properties that enable such a transient form of adhesion under the high forces experienced by cells in blood vessels.
Whenever possible, we make connections between basic research and disease. These include inherited defects of integrins in leukocyte adhesion deficiency, ICAM-1 as the cellular receptor for rhinovirus, and SDF-1 as the natural ligand for the HIV coreceptor CXCR4. Our work may lead to clinical treatments for autoimmune and vascular diseases.
Yalamanchili, P., Lu, C., Oxvig, C., Springer, T.A. (2000). Folding and function of I-domain deleted Mac-1 and LFA-1. J. Biol. Chem. 275:21877.
Zang, Q., Lu, C., Huang, C., Takagi, J. and Springer, T.A. (2000). The top of the I-like domain of the integrin LFA-1 b subunit contacts the a subunit b-propeller domain near b-sheet 3. J. Biol. Chem. 275:22202.
Huang, C., Zang, Q., Takagi, J., and Springer, T. A. (2000). Structural and functional studies with antibodies to the integrin b2 subunit: A model for the I-like domain. J. Biol. Chem. 275:21514.
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