Compositions and methods for regulating receptor clustering

Abstract

The invention relates to isolated complexes comprising one or more galectin associated with a Mgat5 modified glycan or polylactosamine modified glycan, and isolated lectin-Mgt5 modified glycan lattice comprising an array of mulitvalent interactions among lectins, Mgat5 modified glycans, polylactosamine modified glycans, and/or glycoproteins. Methods for evaluating a test compound for its ability to regulate receptor clustering through glycans on cell surfaces; and methods for regulating receptor clustering on cell surfaces comprising altering glycans on the cell surface associated with receptor clustering are also disclosed.

1 . An isolated lectin-Mgat5 modified glycan lattice comprising an array of multivalent interactions among lectins, Mgat5 modified glycans, polylactosamine modified glycans, and/or glycoproteins that are associated with receptor clustering. 
     
     
         2 . An isolated lectin-Mgat5 modified glycan lattice as claimed in  claim 1  wherein the Mgt5 modified glycans and polylactosamine modified glycans are part of glycoproteins of receptors. 
     
     
         3 . A method for evaluating a compound for its ability to regulate receptor clustering through a lectin-Mgat5 modified glycan lattice, the method comprising (a) mixing a lectin-Mgat5 modified glycan lattice as claimed in  claim 1 , or a lectin and one or more of a Mgat5 modified glycan and polylactosamine modified glycan, and a test compound, under conditions which maintain the lattice or permit the formation of complexes between the lectin and one or more of the Mgat5 modified glycan and polylactosamine modified glycan; and (b) removing and/or detecting lectin-Mgat5 modified glycan lattice, complexes, lectin, Mgat5 modified glycan, or polylactosamine modified glycan. 
     
     
         4 . A method as claimed in  claim 3 , wherein the lectin-Mgat5 modified glycan lattice is a galectin-Mgat5 modified glycan lattice and the lectin is a galectin. 
     
     
         5 . A method for (i) regulating receptor clustering on cell surfaces or (ii) treating or preventing a condition associated with decreased or increased receptor clustering or a receptor clustering defect in a subject, the method comprising altering glycans associated with receptor clustering. 
     
     
         6 . A method as claimed in  claim 5 , wherein the receptor is selected from the group consisting of a receptor that stimulates immune reactions T cell receptor, Ig receptor, B cell receptor, NK receptor, a member of the HER family of transmembrane receptor tyrosine kinases, a cadherin receptor, an interleukin (IL) receptor, TNFγ receptor, and an integrin. 
     
     
         7 . A method as claimed in  claim 5 . wherein the glycans are altered by modulating one or more glycosyltransferase enzyme involved in the synthesis of the glycans 
     
     
         8 . A method as claimed in  claim 7 , wherein the glycans are Mgat5 modified glycans and the glycosyltransferase is Mgat5. 
     
     
         9 . A method as claimed in  claim 7 , wherein the glycans are polylactosamine modified glycans and the glycosyltransferase is Mgat5. 
     
     
         10 . A method for regulating receptor clustering on cell surfaces comprising modulating Mgat5 activity, the amount of Mgat5 modified glycans, polylactosamine modified glycans, or THE lectin-Mgat5 modified glycan lattice as claimed in  claim 1 , or the amount of binding or interaction of one or more components of the lectin-Mgat5 modified glycan lattice. 
     
     
         11 . A method as claimed in  claim 5 , the method comprising increasing the amount of Mgat5 modified glycans, polylactosamine modified glycans, or lectin-Mgat5 modified glycan lattice on the cell surface. 
     
     
         12 . A method for restricting T cell receptor recruitment in response to an agonist or increasing T cell activation threshold comprising increasing Mgat5 modified glycans, polylactosamine modified glycans, or the galectin-Mgat5 modified glycan lattice as claimed in  claim 1  on the surface of the cells, or enhancing the interaction between one or more components of the galectin-Mgat5 modified glycan lattice. 
     
     
         13 . A method as claimed in  claim 12 , wherein the glycans or lattice are increased by increasing the amount or activity of one or more glycosyltransferase enzyme. 
     
     
         14 . A method as claimed in  claim 5  which is for increasing receptor clustering on a cell surface by decreasing the amount of Mgat5 modified glycans, polylactosamine modified glycans, or lectin-Mgat5 modified glycan lattice on the cell surface. 
     
     
         15 . A method for lowering T cell activation threshold to agonists or enhancing T cell receptor clustering comprising decreasing Mgat5 modified glycans, polylactosamine modified glycans, or galectin-Mgat5 modified glycan lattice on the surface of the T cells, or dissociating galectin from such glyeans or lattice thereby lowering the T cell activation threshold. 
     
     
         16 . A method as claimed in  claim 15 , wherein the glycans or lattice are decreased by decreasing the amount of or activity of a glycosyltransferase. 
     
     
         17 . A method for treating or preventing a condition associated with decreased or increased receptor clustering, or a receptor clustering defect, comprising modulating Mgat5 activity, the amount of Mgat5 modified glycans, polylactosamine modified glycans, or lectin-Mgat5 modified glycan lattice, or the amount of binding or interaction of one or more components of the lectin-MgatV modified glycan lattice as claimed in  claim 1 . 
     
     
         18 . A method for treating or preventing an autoimmune disease in a subject comprising reducing T cell receptor clustering in the subject by increasing the amount of Mgat5 modified glycans, polylactosamine modified glycans, and/or the lectin-Mgat5 modified glycan lattice as claimed in  claim 1  on the surface of T cells of the subject. 
     
     
         19 . A method of diagnosing and monitoring conditions characterized by an abnormality in receptor clustering comprising assaying for Mgat5 modified glycans, the polylactosamine modified glycans, lectin-Mgat5 modified glycan lattice as claimed in  claim 1 , or alterations in such glycans or lattice, compared to a control. 
     
     
         20 . A method of diagnosing and monitoring conditions characterized by an abnormality or defect of receptor clustering involving the interaction of a galectin and Mgat5 modified glycan or polylactosamine modified glycan comprising determining the presence of one or more complex as claimed in  claim 1 , a Mgat5 modified glycan, a polylactosamine modified glycan, or one or more of an altered Mgat5 modified glycan, polylactosamine modified glycan, or a galectin-Mgat5 modified glycan lattice.