Mouse neutrophilic granulocytes express mRNA encoding the macrophage colony-stimulating factor receptor (CSF-1R) as well as many other macrophage-specific transcripts and can transdifferentiate into macrophages in vitro in response to CSF-1.
The differentiation of macrophages from their progenitors is controlled by macrophage colony-stimulating factor (CSF-1), which binds to a receptor (CSF-1R) encoded by the c-fms proto-oncogene. We have previously used the promoter region of the CSF-1R gene to direct expression of an enhanced green fluorescent protein (EGFP) reporter gene to resident macrophage populations in transgenic mice. In this paper, we show that the EGFP reporter is also expressed in all granulocytes detected with the Gr-1 antibody, which binds to Ly-6C and Ly-6G or with a Ly-6G-specific antibody. Transgene expression reflects the presence of CSF-1R mRNA but not CSF-1R protein. The same pattern is observed with the macrophage-specific F4/80 marker. Based on these findings, we performed a comparative array profiling of highly purified granulocytes and macrophages. The patterns of mRNA expression differed predominantly through granulocyte-specific expression of a small subset of transcription factors (Egr1, HoxB7, STAT3), known abundant granulocyte proteins (e.g., S100A8, S100A9, neutrophil elastase), and specific receptors (fMLP, G-CSF). These findings suggested that appropriate stimuli might mediate rapid interconversion of the major myeloid cell types, for example, in inflammation. In keeping with this hypothesis, we showed that purified Ly-6G-positive granulocytes express CSF-1R after overnight culture and can subsequently differentiate to form F4/80-positive macrophages in response to CSF-1.
Sasmono
R Tedjo
RT
CRC for Chronic Inflammatory Diseases and ARC Special Research Centre for Functional and Applied Genomics, Institute for Molecular Bioscience, The University of Queensland, St. Lucia, Australia.
Ehrnsperger
Achim
A
Cronau
Stephen L
SL
Ravasi
Timothy
T
Kandane
Rangi
R
Hickey
Michael J
MJ
Cook
Andrew D
AD
Himes
S Roy
SR
Hamilton
John A
JA
Hume
David A
DA
D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects*; D002478:Cells, Cultured; D020869:Gene Expression Profiling; D006098:Granulocytes / Q000166:cytology* / Q000378:metabolism*; D016173:Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D008264:Macrophages / Q000166:cytology*; D051379:Mice; D009504:Neutrophils / Q000166:cytology; D012333:RNA, Messenger / Q000032:analysis; D016186:Receptor, Macrophage Colony-Stimulating Factor / Q000235:genetics*
D012333:RNA, Messenger; D016173:Macrophage Colony-Stimulating Factor; D016186:Receptor, Macrophage Colony-Stimulating Factor