Asrij/OCIAD1 expression delineates functionally distinct hematopoietic stem cells in the bone marrow

Area of Science:

• Hematology
• Stem Cell Biology
• Mitochondrial Biology

Background:

• Hematopoietic stem cells (HSCs) in bone marrow (BM) exhibit significant molecular and functional heterogeneity.
• Understanding intrinsic factors driving HSC diversity is crucial for targeted HSC enrichment and predictable differentiation outcomes.
• The mitochondrial protein Asrij/OCIAD1 is a known regulator of hematopoietic homeostasis.

Purpose of the Study:

• To investigate the role of Asrij expression levels in governing HSC heterogeneity and function.
• To develop a novel reporter mouse model for live isolation of HSCs based on Asrij expression.
• To elucidate how Asrij impacts HSC quiescence, self-renewal, and differentiation potential.

Main Methods:

• Generation of a novel Asrij-mNeonGreen (mNG) knock-in reporter mouse using CRISPR-Cas9 technology.
• Isolation of live HSCs based on heterogeneous Asrij expression levels.
• Ex vivo culture, transplantation assays, and transcriptomic analysis of Asrij-expressing HSCs.

Main Results:

• Asrij expression is heterogeneous within the HSC population, with Asrijlow HSCs showing enhanced self-renewal and quiescence.
• Asrijhigh HSCs are primed for differentiation and exhibit hallmarks of HSC activation.
• Asrijlow HSCs demonstrated superior reconstitution capacity in BM HSPC and myeloid compartments.
• The Asrij-mNG reporter mouse accurately reflects endogenous Asrij expression and enables cell isolation.

Conclusions:

• Asrij protein levels are a key determinant of HSC functional diversity, influencing quiescence, self-renewal, and differentiation.
• The Asrij-mNG reporter mouse serves as a valuable tool for studying the molecular basis of HSC functional heterogeneity.
• This research provides insights into mechanisms controlling HSC pool diversity for potential therapeutic applications.