Tacke, RobertHilgendorf, IngoGarner, HannahWaterborg, ClairePark, KiwonNowyhed, HebaHanna, Richard N.Wu, RunpeiSwirski, FilipGeissmann, FredericHedrick, Catherine C.2015-08-032015Tacke, R., I. Hilgendorf, H. Garner, C. Waterborg, K. Park, H. Nowyhed, R. N. Hanna, et al. 2015. “The transcription factor NR4A1 is essential for the development of a novel macrophage subset in the thymus.” Scientific Reports 5 (1): 10055. doi:10.1038/srep10055. http://dx.doi.org/10.1038/srep10055.2045-2322http://nrs.harvard.edu/urn-3:HUL.InstRepos:17820866Tissue macrophages function to maintain homeostasis and regulate immune responses. While tissue macrophages derive from one of a small number of progenitor programs, the transcriptional requirements for site-specific macrophage subset development are more complex. We have identified a new tissue macrophage subset in the thymus and have discovered that its development is dependent on transcription factor NR4A1. Functionally, we find that NR4A1-dependent macrophages are critically important for clearance of apoptotic thymocytes. These macrophages are largely reduced or absent in mice lacking NR4A1, and Nr4a1-deficient mice have impaired thymocyte engulfment and clearance. Thus, NR4A1 functions as a master transcription factor for the development of this novel thymus-specific macrophage subset.en-USJournal Article2015-08-0310.1038/srep10055