title: TCRbeta enhancer activation in early and late lymphoid progenitors.
abstract: An earlier report from our laboratory indicates that the activation of the T cell receptor (TCR) beta enhancer (Ebeta) is not always an indicator of T lineage potential in bone marrow-resident pre-lymphocytes. In order to more precisely investigate the consequences of Ebeta activation in lymphopoiesis, a genetic reporter animal, in which the expression of green fluorescent protein (GFP) is controlled by Ebeta, was used to examine two well-defined lymphopotent populations. Adoptive transfer experiments suggest that primitive lymphoid precursor populations (specifically, hematopoietic stem cells) consist of two discrete-populations discernible by Ebeta-GFP activation, although the two populations display no overt differences in lineage potential. In contrast, subsets of more differentiated pre-lymphocytes (specifically, common lymphoid progenitors), while also discernible by Ebeta-GFP activation, display different capacities for reconstituting lymphoid compartments. Interestingly, late lymphoid progenitors containing inactive Ebeta elements generated both T and B cells in vivo, in accord with the original description of this population; however, progenitors containing active Ebeta elements displayed an unexpected bias toward the B lineage. Our findings suggest that Ebeta activation is an indicator of B lineage specification in late, but not early lymphoid precursors.
authors.affiliation: Department of Microbiology and Immunology, Louisiana State University Health Sciences Center, 1501 Kings Highway, Shreveport, LA 71130, USA.
authors.forename: Hillary H
authors.initials: HH
authors.lastname: Norris
authors.forename: Aaron J
authors.initials: AJ
authors.lastname: Martin
authors.forename: Lonnie P
authors.initials: LP
authors.lastname: Lybarger
authors.forename: Hanne
authors.initials: H
authors.lastname: Andersen
authors.forename: Deborah C
authors.initials: DC
authors.lastname: Chervenak
authors.forename: Robert
authors.initials: R
authors.lastname: Chervenak
mesh_terms: D000818:Animals; D001854:Bone Marrow Cells / Q000166:cytology; D002452:Cell Count; D002454:Cell Differentiation; D019070:Cell Lineage / Q000235:genetics*; D004742:Enhancer Elements, Genetic / Q000235:genetics*; D005786:Gene Expression Regulation / Q000235:genetics*; D017930:Genes, Reporter / Q000235:genetics; D006412:Hematopoietic Stem Cells / Q000378:metabolism; D054503:Lymphoid Progenitor Cells / Q000166:cytology / Q000276:immunology* / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D016693:Receptors, Antigen, T-Cell, alpha-beta / Q000235:genetics* / Q000276:immunology* / Q000378:metabolism; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013154:Spleen / Q000276:immunology / Q000378:metabolism; D013997:Time Factors; D014158:Transcription, Genetic / Q000235:genetics
chemical_list: D016693:Receptors, Antigen, T-Cell, alpha-beta; D011994:Recombinant Proteins