Gene expression fluctuations in murine hematopoietic stem cells with cell cycle progression

Area of Science:

• Hematology
• Stem Cell Biology
• Molecular Biology

Background:

• Marrow hematopoietic stem cells (HSCs) are crucial for blood formation and exhibit dynamic properties.
• Traditional hierarchical models of HSC regulation are being challenged by evolving data on phenotype lability.

Purpose of the Study:

• To investigate mRNA expression in murine HSCs during cell cycle progression.
• To explore the phenotypic plasticity of HSCs in response to cytokine stimulation.

Main Methods:

• Isolated murine lineage negative Sca-1 positive (LSK) stem cells.
• Analyzed mRNA expression of cell surface epitopes and transcription regulators.
• Induced cell cycle transit in vitro using specific cytokines (IL-3, IL-6, IL-11, steel factor).

Main Results:

• LSK stem cells expressed a broad range of markers and transcription factors at isolation.
• Cytokine-induced cell cycle progression led to reversible changes in the expression of certain genes (e.g., Sca-1, Mac-1, c-fms, c-mpl).
• Other genes (e.g., CD34, c-kit, Gata-2) maintained stable expression despite cell cycle transit.

Conclusions:

• Murine HSCs display significant and reversible phenotypic lability in gene expression with cell cycle transit.
• These findings support a continuum model for stem cell regulation, extending it to include cell cycle-dependent reversible gene expression.
• Phenotypic plasticity is a key feature of HSC regulation, influenced by cell cycle dynamics and cytokine signaling.