In vitro gene signature of cultured adult keratinocytes stimulated by all trans retinoic acid (atRA) and/or Poly I:C

How developmental programs reactivate in regeneration is a fundamental question in biology. We addressed this question through the study of Wound Induced Hair follicle Neogenesis (WIHN), an adult organogenesis model where stem cells regenerate entirely new hair follicles de novo following deep wounding. The exact mechanism is uncertain. Here we show that self-noncoding dsRNA activates the anti-viral receptor TLR3 to induce intrinsic retinoic acid (RA) synthesis in a gradient that predicts new hair follicle formation after wounding in mice. Additionally, in humans, rejuvenation lasers induce gene expression signatures for dsRNA and RA, with measurable increases in intrinsic RA synthesis. These results demonstrate a novel stimulus for retinoic acid synthesis by non-coding dsRNA, relevant to their broad functions in development and immunity. Hand keratinocytes were treated with atRA (0.1 uM) and/or Poly I:C (0.1 ug/ml). RNA was extracted and sent for microarray analysis Keratinocytes were isolated from one source of human hand (dorsal palm). Cells were cultured in KGM-GOLD (Keratincoytes growth media from Lonza) supplemented with ROCK inhibitor (10 uM; Y-27632) and treated with atRA (0.1 uM) for 2 days and Poly I:C (0.1 ug/ml) for 3 days. Total RNAs were extracted from the three treatments plus one control and sent for microarray analysis