High interleukin-3 concentrations prime murine myeloid progenitor cells towards granulocytic differentiation

Impaired differentiation a key feature of many hematopoietic malignancies. To decipher the molecular processes underlying malignant transformation, it is important to understand the mechanisms regulating hematopoietic differentiation. Cell lines derived from transformed hematopoietic progenitors or from leukemia patients have proven to be valuable model systems for mechanistic investigations of hematopoiesis. In the present work, we investigated the cell-intrinsic differentiation capacity of the interleukin 3 (IL-3) dependent murine myeloid progenitor cell line 32D. We demonstrated that 32D cells have a cell-intrinsic granulocytic differentiation potential which requires the presence of high IL-3 concentrations in order to induce granulocytic priming. We also show that 32D cells still proliferate at comparable rates but lack granulocytic priming in the presence of intermediate IL-3 concentrations. This phenotypic plasticity is fully reversible and entirely depends on the IL-3 concentrations present in the culture media. RNA-seq analysis revealed that, among other myeloid genes, the expression of Csf3r is strongly induced exclusively in the presence of high IL-3 concentrations, likely explaining the granulocytic differentiation in response to G-CSF treatment. Together, our work provides detailed cellular and molecular insights into the phenotypic plasticity of 32D cells driven by different IL-3 concentrations and suggest culture conditions for different experimental set ups. Key points 32D cells represent a murine myeloid cell line with endogenous granulocytic differentiation potential. 32D cells present molecular and functional plasticity depending on their culture conditions. High IL-3 culture conditions prime 32D cells towards the granulocytic lineage. Low IL-3 culture conditions lead to a reversible loss of the granulocytic differentiation potential of 32D cells while fully maintaining their proliferative activity.