Notch3/Jagged1 circuitry reinforces notch signaling and sustains T-ALL

Area of Science:

• Oncology
• Molecular Biology
• Cell Signaling

Background:

• Deregulated Notch signaling is implicated in T-cell acute lymphoblastic leukemia (T-ALL).
• The interplay between Notch3 receptor and Jagged1 ligand in T-ALL pathogenesis requires further elucidation.

Purpose of the Study:

• To investigate the direct relationship between Notch3 receptor and Jagged1 ligand in T-ALL.
• To elucidate the mechanism of Jagged1 processing and its role in Notch signaling in T-ALL.

Main Methods:

• Utilized human cell lines and a mouse model of T-ALL.
• Investigated Jagged1 as a Notch3 signaling target gene.
• Analyzed Jagged1 processing in Notch3-IC-overexpressing T lymphoma cells.
• Assessed the impact of Jagged1 extracellular domain release on Notch signaling.

Main Results:

• Identified Jagged1 as a novel Notch3 signaling target gene, leading to aberrant cis-expression.
• Demonstrated constitutive processing of Jagged1 in T lymphoma cells, involving raft-association and proteolytic cleavage.
• Showed that Jagged1 intracellular domain enhances Notch signaling and its own transcription (autocrine effect).
• Revealed that soluble Jagged1 extracellular domain activates Notch signaling in adjacent cells (paracrine effect).
• Established a Notch3/Jagged1 auto-sustaining loop promoting lymphoma cell survival, proliferation, and invasion.
• Correlated high Jagged1 expression with adverse prognosis in T-ALL patients.

Conclusions:

• The Notch3/Jagged1 axis forms a critical auto-sustaining loop in T-ALL.
• This loop drives T-ALL progression and is associated with poor patient prognosis.
• Targeting the Notch3/Jagged1 interaction may offer therapeutic strategies for T-ALL.