title: Galectin-1 tunes TCR binding and signal transduction to regulate CD8 burst size.
abstract: T cell burst size is regulated by the duration of TCR engagement and balanced control of Ag-induced activation, expansion, and apoptosis. We found that galectin-1-deficient CD8 T cells undergo greater cell division in response to TCR stimulation, with fewer dividing cells undergoing apoptosis. TCR-induced ERK signaling was sustained in activated galectin-1-deficient CD8 T cells and antagonized by recombinant galectin-1, indicating galectin-1 modulates TCR feed-forward/feedback loops involved in signal discrimination and procession. Furthermore, recombinant galectin-1 antagonized binding of agonist tetramers to the TCR on activated OT-1 T cells. Finally, galectin-1 produced by activated Ag-specific CD8 T cells negatively regulated burst size and TCR avidity in vivo. Therefore, galectin-1, inducibly expressed by activated CD8 T cells, functions as an autocrine negative regulator of peripheral CD8 T cell TCR binding, signal transduction, and burst size. Together with recent findings demonstrating that gal-1 promotes binding of agonist tetramers to the TCR of OT-1 thymocytes, these studies identify galectin-1 as a tuner of TCR binding, signaling, and functional fate determination that can differentially specify outcome, depending on the developmental and activation stage of the T cell.
authors.affiliation: Department of Microbiology, Immunology, and Molecular Genetics, University of California, Los Angeles, CA 90095-1570, USA.
authors.forename: Scot D
authors.initials: SD
authors.lastname: Liu
authors.forename: Tamar
authors.initials: T
authors.lastname: Tomassian
authors.forename: Kevin W
authors.initials: KW
authors.lastname: Bruhn
authors.forename: Jeff F
authors.initials: JF
authors.lastname: Miller
authors.forename: Françoise
authors.initials: F
authors.lastname: Poirier
authors.forename: M Carrie
authors.initials: MC
authors.lastname: Miceli
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000235:genetics / Q000276:immunology; D019898:Autocrine Communication / Q000276:immunology; D018414:CD8-Positive T-Lymphocytes / Q000166:cytology* / Q000276:immunology* / Q000378:metabolism / Q000637:transplantation; D002454:Cell Differentiation / Q000235:genetics / Q000276:immunology; D002455:Cell Division / Q000235:genetics / Q000276:immunology; D049109:Cell Proliferation; D015536:Down-Regulation / Q000235:genetics / Q000276:immunology; D005260:Female; D037483:Galectin 1 / Q000096:biosynthesis / Q000172:deficiency / Q000235:genetics / Q000502:physiology*; D008213:Lymphocyte Activation / Q000235:genetics / Q000276:immunology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D011485:Protein Binding / Q000235:genetics / Q000276:immunology; D011948:Receptors, Antigen, T-Cell / Q000037:antagonists & inhibitors / Q000172:deficiency / Q000378:metabolism* / Q000502:physiology; D015398:Signal Transduction / Q000235:genetics / Q000276:immunology*
chemical_list: D037483:Galectin 1; D011948:Receptors, Antigen, T-Cell