Stat3 and CCAAT enhancer–binding protein β (C/ebpβ) activate Fanconi C gene transcription during emergency granulopoiesis

Interferon consensus sequence-binding protein (Icsbp) is required for terminating emergency granulopoiesis, an episodic event responsible for granulocyte production in response to infections and a key component of the innate immune response. Icsbp inhibits expression of Stat3 and C/ebpβ, transcription factors essential for initiating and sustaining granulopoiesis, and activates transcription of Fanconi C (FANCC); a DNA repair protein. In prior studies, we noted accelerated bone marrow failure in Fancc-/- mice undergoing multiple episodes of emergency granulopoiesis, associated with apoptosis of bone marrow cells with unrepaired DNA damage. Additionally, we found increased expression of Fanconi C and F proteins during emergency granulopoiesis. These findings suggest that Icsbp protects the bone marrow from DNA damage by increasing activity of the Fanconi DNA repair pathway, but the mechanisms for FANCC activation during initiation of emergency granulopoiesis are unclear. In the current study, we observed that Stat3 and C/ebpβ activate FANCC transcription and contribute to DNA repair. Our finding indicate that FancC expression is increased during Stat3- and C/ebpβ-induced initiation of emergency granulopoiesis by these transcription factors, and is maintained through termination by Icsbp. Our work reveals that Stat3- and C/ebpβ-mediate FancC expression as a critical component for initiating and sustaining the key innate immune responses.