12:00pm - 1:00pm|
Microbiology & Immunology Seminar Series
Gerardo R. Vasta, Ph.D., Professor of Microbiology and Immunology, University of Maryland School of Medicine
Title: "The sweet tooth of innate immunity: Lectins as self/non-self recognition proteins"
Host: Jacques Robert
Seminar Abstract: Although lectins display a limited diversity in recognition, the presence of tandemly arrayed carbohydrate recognition domains (CRDs), of chimeric structures displaying distinct CRDs, of polymorphic genes resulting in multiple isoforms, and in some cases, of a considerable recognition plasticity of their carbohydrate binding sites, significantly expand the lectin ligand-recognition spectrum and lectin functional diversification. In this regard, analysis of structural/functional aspects of F-lectinsthe most recently identified lectin family characterized by a unique CRD sequence motif, a distinctive structural fold, and nominal specificity for L-Fuchas led to a greater understanding of non-self recognition by proteins with tandemly arrayed CRDs. In contrast, galectins were initially considered to bind endogenous ("self") glycans and mediate developmental processes, including cell differentiation and tissue organization or regeneration. In the past few years, numerous studies have described the diverse regulatory effects of galectins on immune homeostasis and cancer. More recently, however, evidence has accumulated to support the notion that galectins also bind exogenous ("non-self") glycans on the surface of potentially pathogenic microbes, parasites, and fungi, suggesting that galectins could function as pattern recognition receptors (PRRs). Galectins, however, can bind similar self/non-self molecular patterns on host and microbial cells. Furthermore, although some galectins can bind and kill bacteria, thereby displaying activity as innate immune recognition and effector factors, it appears that in most cases galectin-mediated recognition favors the potential pathogen rather than the host. Therefore, some galectins do not fit the definition of PRRs, underscoring the significant gaps in our knowledge about the structural and functional diversity, subcellular targeting, localization, and secretion of the galectin repertoire components in any given species, and the host-parasite co-evolutionary processes that have resulted in such interactions.
|Location: ||K-307 (Room 3-6408)|
Posted by: Corrine Aleese, Micro & Immunolgy, 25-Sep-13 10:34am ET