Fate Decision Between Group 3 Innate Lymphoid and Conventional NK Cell Lineages by Notch Signaling in Human...

Area of Science:

• Immunology
• Cell Biology
• Hematopoiesis

Background:

• The role of Notch signaling in human innate lymphoid cell (ILC) differentiation remains largely undefined.
• Interleukins 7 (IL-7) and 15 (IL-15) are known to promote the differentiation of natural cytotoxicity receptor (NCR)+ group 3 ILCs (NCR+ILC3s) and conventional NK (cNK) cells from hematopoietic progenitor cells (HPCs).
• Understanding Notch's function is crucial for elucidating ILC and NK cell lineage commitment.

Purpose of the Study:

• To investigate the specific functions of Notch signaling in the differentiation of NCR+ILC3s and cNK cells from distinct human HPC subpopulations.
• To analyze the impact of Notch signaling on cell fate decisions at different maturational stages of human HPCs.
• To identify the molecular mechanisms underlying Notch's role in ILC and cNK cell lineage commitment.

Main Methods:

• Analysis of Notch signaling functions in human peripheral blood HPC subpopulations using limiting dilution and clonal assays.
• High-throughput flow cytometry was employed to assess cell differentiation and potential.
• Inhibition of Notch signaling using antibodies targeting Notch1 and Notch2.

Main Results:

• Notch signaling, combined with IL-7, induced NCR+ILC3 differentiation from CD45RA+Flt-3-c-Kitlow HPCs, while suppressing IL-15-dependent cNK cell generation.
• Notch signaling promoted the generation of earliest thymic progenitor-like cells from CD45RA-Flt-3+c-Kithigh HPCs, preserving cNK/T cell potential but losing NCR+ILC3 potential.
• Both Notch1 and Notch2 signaling were implicated in the fate decision of innate lymphocyte-committed HPCs and the generation of progenitor-like cells.

Conclusions:

• Notch signaling exhibits countervailing functions in the fate decision between NCR+ILC3 and cNK cell lineages at different human HPC maturational stages.
• Notch signaling plays a pivotal role in the transcriptional control required for human NCR+ILC3 commitment, partly by inducing IL-7 receptor expression.
• These findings highlight Notch's critical regulatory role in innate lymphoid cell development and lineage commitment.