Notch target Hes5 ensures appropriate Notch induced T- versus B-cell choices in the thymus.
Notch signaling establishes boundaries in the thymus by inducing T-cell commitment and inhibiting a B-cell choice. Here, we show a significant 1.6-fold increased generation of B-cell precursors in thymuses from mice deficient for Notch target Hes5 compared with wild-type littermates. We further show that culture of bone marrow-derived progenitors with increasing densities of purified immobilized Notch ligand (Delta1(ext-IgG)) induced increased expression of Notch targets Hes1 and Hes5, and that although Hes5-deficient progenitors responded appropriately to high densities of ligand, they misread intermediate and low densities. Together, our results suggest that to ensure an appropriate outcome in the thymus in response to a lower threshold of induced Notch signaling, induction of the additional target Hes5 is required.
Clinical Research Division, Fred Hutchinson Cancer Research Center, 1100 Fairview Avenue N., Seattle, WA 98109, USA. bvarnumf@fhcrc.org
Barbara
B
Varnum-Finney
Mari H
MH
Dallas
Keizo
K
Kato
Irwin D
ID
Bernstein
D000818:Animals; D001402:B-Lymphocytes / Q000166:cytology*; D051792:Basic Helix-Loop-Helix Proteins / Q000235:genetics / Q000378:metabolism*; D002452:Cell Count; D005786:Gene Expression Regulation; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins; D008024:Ligands; D008565:Membrane Proteins / Q000378:metabolism; D051379:Mice; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051880:Receptors, Notch / Q000378:metabolism*; D012097:Repressor Proteins / Q000235:genetics / Q000378:metabolism*; D013234:Stem Cells / Q000166:cytology; D016176:T-Lymphocyte Subsets / Q000166:cytology; D013601:T-Lymphocytes / Q000166:cytology*; D013950:Thymus Gland / Q000166:cytology*
D051792:Basic Helix-Loop-Helix Proteins; D047908:Intracellular Signaling Peptides and Proteins; D008024:Ligands; D008565:Membrane Proteins; D012333:RNA, Messenger; D051880:Receptors, Notch; D012097:Repressor Proteins; C489685:Hes5 protein, mouse; C064045:delta protein