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Delayed, asynchronous, and reversible T-lineage specification induced by Notch/Delta signaling
Tom N Taghon1, Elizabeth-Sharon David, Juan Carlos Zúñiga-Pflücker
1Division of Biology, California Institute of Technology, Pasadena, California 91125, USA.
Genes & Development
|April 19, 2005
Summary
Notch signaling is necessary but not sufficient for T-cell development. Hematopoietic stem cells require delayed Notch/Delta signaling for T-lineage specification, allowing for potential B-cell differentiation.
Area of Science:
- Developmental biology
- Immunology
- Stem cell biology
Background:
- Notch/Delta signaling is crucial for T-cell development.
- The precise timing and sufficiency of Notch signaling in lineage commitment remain unclear.
Purpose of the Study:
- To investigate the temporal dynamics of Notch/Delta signaling in T-lineage specification.
- To determine if Notch signaling alone is sufficient for T-cell commitment.
Main Methods:
- Utilized the OP9-DL1 co-culture system for controlled Notch/Delta signaling.
- Employed clonal switch-culture analysis to track lineage potential.
- Monitored gene expression of lineage-specific transcription factors.
Main Results:
- Pluripotent progenitors showed delayed and asynchronous T-lineage specification and B-lineage inhibition upon Notch signaling.
- Progenitors required over 3 days to initiate T- or B-lineage differentiation.
- Lineage-specific gene expression was reversible, indicating plasticity.
- Notch target genes were induced similarly in both slow and rapid responders.
Conclusions:
- Notch/Delta signaling is necessary but not sufficient for T-cell lineage specification and commitment.
- This signaling pathway may maintain uncommitted progenitors, challenging binary-choice models of hematopoiesis.