Recruitment of adult thymic progenitors is regulated by P-selectin and its ligand PSGL-1.
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.
Rossi
Fabio M V
FM
The Biomedical Research Centre, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada. Fabio@brc.ubc.ca
Corbel
Stephane Y
SY
Merzaban
Jasmeen S
JS
Carlow
Douglas A
DA
Gossens
Klaus
K
Duenas
Jeffrey
J
So
Leslie
L
Yi
Lin
L
Ziltener
Hermann J
HJ
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
D008024:Ligands; D008562:Membrane Glycoproteins; D019007:P-Selectin; C084882:P-selectin ligand protein