title: Identification, characterization, and epitope mapping of human monoclonal antibody J19 that specifically recognizes activated integrin α4β7.
abstract: Integrin α(4)β(7) is a lymphocyte homing receptor that mediates both rolling and firm adhesion of lymphocytes on vascular endothelium, two of the critical steps in lymphocyte migration and tissue-specific homing. The rolling and firm adhesions of lymphocytes rely on the dynamic shift between the inactive and active states of integrin α(4)β(7), which is associated with the conformational rearrangement of integrin molecules. Activation-specific antibodies, which specifically recognize the activated integrins, have been used as powerful tools in integrin studies, whereas there is no well characterized activation-specific antibody to integrin α(4)β(7). Here, we report the identification, characterization, and epitope mapping of an activation-specific human mAb J19 against integrin α(4)β(7). J19 was discovered by screening a human single-chain variable fragment phage library using an activated α(4)β(7) mutant as target. J19 IgG specifically bound to the high affinity α(4)β(7) induced by Mn(2+), DTT, ADP, or CXCL12, but not to the low affinity integrin. Moreover, J19 IgG did not interfere with α(4)β(7)-MAdCAM-1 interaction. The epitope of J19 IgG was mapped to Ser-331, Ala-332, and Ala-333 of β(7) I domain and a seven-residue segment from 184 to 190 of α(4) β-propeller domain, which are buried in low affinity integrin with bent conformation and only exposed in the high affinity extended conformation. Taken together, J19 is a potentially powerful tool for both studies on α(4)β(7) activation mechanism and development of novel therapeutics targeting the activated lymphocyte expressing high affinity α(4)β(7).
authors.affiliation: State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200031, China.
authors.forename: JunPeng
authors.initials: J
authors.lastname: Qi
authors.forename: Kun
authors.initials: K
authors.lastname: Zhang
authors.forename: Qiao
authors.initials: Q
authors.lastname: Zhang
authors.forename: Yi
authors.initials: Y
authors.lastname: Sun
authors.forename: Ting
authors.initials: T
authors.lastname: Fu
authors.forename: GuoHui
authors.initials: G
authors.lastname: Li
authors.forename: JianFeng
authors.initials: J
authors.lastname: Chen
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000276:immunology* / Q000378:metabolism; D000918:Antibody Specificity / Q000276:immunology*; D018604:Epitope Mapping / Q000379:methods*; D000939:Epitopes / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D005434:Flow Cytometry; D057809:HEK293 Cells; D006801:Humans; D007074:Immunoglobulin G / Q000737:chemistry / Q000276:immunology / Q000378:metabolism; D016023:Integrins / Q000737:chemistry / Q000235:genetics / Q000276:immunology*; D020014:K562 Cells; D051379:Mice; D008856:Microscopy, Fluorescence; D008958:Models, Molecular; D009154:Mutation; D019151:Peptide Library; D011134:Polysaccharides / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D055503:Protein Multimerization; D017434:Protein Structure, Tertiary; D051381:Rats; D057127:Single-Chain Antibodies / Q000235:genetics / Q000276:immunology / Q000378:metabolism
chemical_list: D000911:Antibodies, Monoclonal; D000939:Epitopes; D007074:Immunoglobulin G; D016023:Integrins; D019151:Peptide Library; D011134:Polysaccharides; D057127:Single-Chain Antibodies; C071777:integrin alpha4beta7