title: Rap1A regulates generation of T regulatory cells via LFA-1-dependent and LFA-1-independent mechanisms.
abstract: The small GTPase Rap1A has a critical role in regulating cell-matrix and cell-cell adhesion. In T lymphocytes, Rap1A mediates LFA-1 activation and LFA-1-mediated adhesion. LFA-1 reduces the threshold of TCR signals for low affinity ligands. Previously, we determined that mice expressing constitutively active Rap1A on T cells have increased frequency of CD103(+) T regulatory cells (Treg). We hypothesized that Rap1A-GTP might affect the differentiation of Treg by regulating LFA-1 activation. Using Foxp3-GFP-KI, LFA-1-KO and Rap1A-GTP-Tg mice we determined that Rap1A has an active role in the development of thymic Treg but LFA-1 is not mandatory for this function. Rap1A is also involved in the generation of peripheral Treg and this effect is mediated via LFA-1-dependent and LFA-1-independent mechanisms. Identification of the signaling pathways via which Rap1-GTP contributes to the differentiation of Treg will provide new insights to the function of Rap1A and to designing targeted approaches for generation of Treg for therapeutic applications.
authors.affiliation: Department of Hematology-Oncology and Cancer Biology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, MA 02215, USA.
authors.forename: Lequn
authors.initials: L
authors.lastname: Li
authors.forename: Jin sub
authors.initials: Js
authors.lastname: Kim
authors.forename: Vassiliki A
authors.initials: VA
authors.lastname: Boussiotis
mesh_terms: D019264:Adoptive Transfer; D000818:Animals; D017252:CD3 Complex / Q000276:immunology; D015496:CD4-Positive T-Lymphocytes / Q000166:cytology / Q000187:drug effects / Q000276:immunology / Q000378:metabolism; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D002452:Cell Count; D002454:Cell Differentiation / Q000187:drug effects / Q000276:immunology*; D049109:Cell Proliferation / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000235:genetics; D051858:Forkhead Transcription Factors / Q000235:genetics / Q000378:metabolism; D008198:Lymph Nodes / Q000166:cytology / Q000276:immunology; D008213:Lymphocyte Activation / Q000276:immunology; D016169:Lymphocyte Function-Associated Antigen-1 / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D013154:Spleen / Q000166:cytology / Q000276:immunology; D050378:T-Lymphocytes, Regulatory / Q000166:cytology* / Q000276:immunology* / Q000378:metabolism; D013950:Thymus Gland / Q000166:cytology / Q000276:immunology; D016212:Transforming Growth Factor beta / Q000494:pharmacology; D020827:rap1 GTP-Binding Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D017252:CD3 Complex; D004268:DNA-Binding Proteins; D051858:Forkhead Transcription Factors; C498833:Foxp3 protein, mouse; D016169:Lymphocyte Function-Associated Antigen-1; C499308:Rag2 protein, mouse; D016212:Transforming Growth Factor beta; D020827:rap1 GTP-Binding Proteins