title: Recruitment of adult thymic progenitors is regulated by P-selectin and its ligand PSGL-1.
abstract: The molecular mechanisms that direct the migration of early T lymphocyte progenitors to the thymus are unknown. We show here that P-selectin is expressed by thymic endothelium and that lymphoid progenitors in bone marrow and thymus bind P-selectin. Parabiosis, competitive thymus reconstitution and short-term homing assays indicated that P-selectin and its ligand PSGL-1 are functionally important components of the thymic homing process. Accordingly, thymi of mice lacking PSGL-1 contained fewer early thymic progenitors and had increased empty niches for prothymocytes compared with wild-type mice. Furthermore, the number of resident thymic progenitors controls thymic expression of P-selectin, suggesting that regulation of P-selectin expression by a thymic 'niche occupancy sensor' may be used to direct progenitor access.
authors.affiliation: The Biomedical Research Centre, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada. Fabio@brc.ubc.ca
authors.forename: Fabio M V
authors.initials: FM
authors.lastname: Rossi
authors.forename: Stephane Y
authors.initials: SY
authors.lastname: Corbel
authors.forename: Jasmeen S
authors.initials: JS
authors.lastname: Merzaban
authors.forename: Douglas A
authors.initials: DA
authors.lastname: Carlow
authors.forename: Klaus
authors.initials: K
authors.lastname: Gossens
authors.forename: Jeffrey
authors.initials: J
authors.lastname: Duenas
authors.forename: Leslie
authors.initials: L
authors.lastname: So
authors.forename: Lin
authors.initials: L
authors.lastname: Yi
authors.forename: Hermann J
authors.initials: HJ
authors.lastname: Ziltener
mesh_terms: D000818:Animals; D002465:Cell Movement; D004727:Endothelium / Q000276:immunology / Q000378:metabolism; D006412:Hematopoietic Stem Cells / Q000166:cytology* / Q000276:immunology / Q000378:metabolism*; D066298:In Vitro Techniques; D008024:Ligands; D008562:Membrane Glycoproteins / Q000172:deficiency / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D019007:P-Selectin / Q000235:genetics / Q000378:metabolism*; D013601:T-Lymphocytes / Q000166:cytology* / Q000276:immunology / Q000378:metabolism*; D013950:Thymus Gland / Q000166:cytology / Q000276:immunology / Q000378:metabolism
chemical_list: D008024:Ligands; D008562:Membrane Glycoproteins; D019007:P-Selectin; C084882:P-selectin ligand protein