HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Schnell, F. J. Articles by Kersh, G. J. Search for Related Content PubMed PubMed Citation Articles by Schnell, F. J. Articles by Kersh, G. J.

Early Growth Response Gene 1 Provides Negative Feedback to Inhibit Entry of Progenitor Cells into the Thymus¹

Department of Pathology and Laboratory Medicine, Emory University School of Medicine, Atlanta, GA 30322

The size of the thymus can be greatly influenced by changes in the small number of early progenitors in the thymus. However, it is not known whether thymic cellularity feeds back to regulate the recruitment, survival, and expansion of progenitors. The transcription factor early growth response gene 1 (Egr1) has been implicated in controlling proliferation and survival in many cell types. We have previously shown that mice deficient in Egr1 have increased thymic cellularity. We now show that Egr1 regulates a negative feedback signal that controls the entry of cells into the thymus. Egr1-deficient mice have higher percentages of early T lineage progenitors in the thymus, yet Egr1-deficient mice have normal numbers of myelolymphoid progenitors in the bone marrow, and Egr1-deficient thymocytes show normal rates of apoptosis and proliferation at all stages of development. Evidence from mixed bone marrow chimeras shows that the ability of Egr1 to control progenitor recruitment is mediated by bone marrow-derived cells, but is not cell autonomous. Furthermore, Egr1-deficient thymuses have increased P-selectin expression. The data suggest that Egr1 mediates a feedback mechanism whereby the number of resident double negative thymocytes controls the entry of new progenitors into the thymus by regulating P-selectin expression on thymic endothelial cells.

This article has been cited by other articles:

				K. Gossens, S. Naus, S. Y. Corbel, S. Lin, F. M.V. Rossi, J. Kast, and H. J. Ziltener Thymic progenitor homing and lymphocyte homeostasis are linked via S1P-controlled expression of thymic P-selectin/CCL25 J. Exp. Med., April 13, 2009; 206(4): 761 - 778. [Abstract] [Full Text] [PDF]

				J. G. Cyster Settling the thymus: immigration requirements J. Exp. Med., April 13, 2009; 206(4): 731 - 734. [Abstract] [Full Text] [PDF]

				F. J. Schnell, N. Alberts-Grill, and B. D. Evavold CD8+ T Cell Responses to a Viral Escape Mutant Epitope: Active Suppression via Altered SHP-1 Activity J. Immunol., February 15, 2009; 182(4): 1829 - 1835. [Abstract] [Full Text] [PDF]