C/EBPγ regulates wound repair and EGF receptor signaling.

We aimed at identifying novel regulators of skin wound healing (WH), in an epidermal scratch WH assay, by a small interfering RNA (siRNA) silencing approach. Several transcription factors have been previously reported to affect wound repair. We here show that gene silencing of the transcription factor CAAT enhancer-binding protein γ (C/EBPγ), STAT3, REL, RELA, RELB, SP1, and NFkB impaired WH in vitro, in keratinocytes, whereas E2F and CREBBP silencing accelerated the WH process. We further characterized C/EBPγ, as its silencing yielded the maximal impairment (52.2 ± 12.5%) of scratch wounding (SW). We found that C/EBPγ silencing inhibited both EGF- and serum-induced keratinocyte migration, whereas C/EBPγ overexpression enhanced cell migration to EGF and to serum via the EGFR. Further, C/EBPγ silencing impaired scratch-induced Y1068 and Y1173 EGFR phosphorylation, as well as Y118 paxillin phosphorylation, key molecules regulating cell migration and epidermal WH. Moreover, C/EBPγ levels were induced in keratinocytes, following both SW and EGF stimulation. C/EBPγ siRNA silencing in vivo impaired WH at 3, 5, 7, and 14 days following excisional wounding in mice inhibited both re-epithelialization and granulation tissue formation, and induced a decrease of arteriole number. In conclusion, we here report that C/EBPγ positively regulates wound repair both in vitro and in vivo, at least in part, by affecting EGFR signaling.