title: Alpha-dystroglycan is involved in positive selection of thymocytes by participating in immunological synapse formation.
abstract: Alpha-dystroglycan has been proved to be involved in lymphocyte activation by participating in immunological synapse (IS) formation. Considering the existence of IS formation in thymic development, we questioned whether alpha-dystroglycan was expressed in thymus and influenced thymic development. In this study, we demonstrated that alpha-dystroglycan was expressed on fetal thymocytes, especially on double-positive (DP, CD4(+)CD8(+)) cells. Blocking alpha-dystroglycan by treatment of fetal thymus organ culture (FTOC) with anti-alpha-dystroglycan antibody IIH6C4 decreased the number of DP cells compared with nontreated or isotype antibody controls. Down-regulation of alpha-dystroglycan by retroviruses carrying antisense cDNA of dystroglycan in reaggregate thymus organ culture (RTOC) further confirmed these results. Enhanced apoptosis of DP cells was observed after blocking alpha-dystroglycan. Interestingly, we found that blocking alpha-dystroglycan reduced IS formation between DP cells and thymic epithelial cells. Furthermore, blocking alpha-dystroglycan up-regulated CD95/CD95L expression and reduced Bcl-2 expression on DP cells in the developing thymus. Finally, the increase in the apoptosis of DP cells was associated with a consequent decrease in the positive selection, as indicated by the reduction of both ERK phosphorylation in DP cells and single-positive (SP, CD4(+) or CD8(+)) cell outcome. Altogether, these results indicated that alpha-dystroglycan was involved in positive selection of thymocytes by participating in the IS formation.
authors.affiliation: Department of Immunology, Shanghai Medical College of Fudan University, 138 Yixueyuan Rd., Shanghai 200032, China.
authors.forename: Yanping
authors.initials: Y
authors.lastname: Gong
authors.forename: Ruihua
authors.initials: R
authors.lastname: Zhang
authors.forename: Jinping
authors.initials: J
authors.lastname: Zhang
authors.forename: Lin
authors.initials: L
authors.lastname: Xu
authors.forename: Feng
authors.initials: F
authors.lastname: Zhang
authors.forename: Wei
authors.initials: W
authors.lastname: Xu
authors.forename: Ying
authors.initials: Y
authors.lastname: Wang
authors.forename: Yiwei
authors.initials: Y
authors.lastname: Chu
authors.forename: Sidong
authors.initials: S
authors.lastname: Xiong
mesh_terms: D000818:Animals; D017209:Apoptosis; D015704:CD4 Antigens / Q000096:biosynthesis; D016827:CD8 Antigens / Q000096:biosynthesis; D049030:Dystroglycans / Q000096:biosynthesis / Q000502:physiology*; D053222:Fas Ligand Protein / Q000502:physiology; D008213:Lymphocyte Activation / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D009924:Organ Culture Techniques; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000502:physiology; D016176:T-Lymphocyte Subsets / Q000276:immunology* / Q000378:metabolism; D013950:Thymus Gland / Q000196:embryology; D019014:fas Receptor / Q000502:physiology
chemical_list: D015704:CD4 Antigens; D016827:CD8 Antigens; D053222:Fas Ligand Protein; D019253:Proto-Oncogene Proteins c-bcl-2; D019014:fas Receptor; D049030:Dystroglycans