Fig. 4

dsRNA induces ALDH1A2/A3 for RA synthesis and accumulation. a RA and Poly (I:C) (0.1 µg per ml) synergistically induce ALDH1A2 and A3 transcription, but not A1 as detected by qRT-PCR in human scalp keratinocytes. (n = 3 independent experiments, *P < 0.05, paired Student t-test). Western blot staining shows ALDH1A3 induced by RA and Poly (I:C) (n = 2). b Genetic (left; siRNA) or chemical (right; DEAB compound) inhibition of ALDH1A2/A3 decrease the ability of Poly (I:C) (0.1 µg per ml) to induce KRT15 and KRT19 in human scalp keratinocytes as detected by western blotting (n = 2 independent experiments). c Genetic inhibition of ALDH1A2/A3 in human keratinocytes reduces RA synthesis in presence of Poly (I:C) (0.5 µg per ml) (n = 3 independent experiments, *P < 0.05, one-way ANOVA). d TLR3 and its downstream mediators are required for stimulation of ALDH1A3 in human scalp keratinocytes (n = 3 independent experiments). e Expression of Aldh1a2 and Aldh1a3 in WT mice during wound healing (n = 3–4 independent animals, *P < 0.05, unpaired Student t-test). f Aldh1a3 but not Aldh1a2 is induced in wild type mice by Poly (I:C) (50 µl; 5 µg per mouse) in early wounds; neither is induced in the Tlr3^−/− mice as detected by qRT-PCR (n = 3 independent animals, *P < 0.05, paired Student t-test). g Schematic of sampling procedure (top). Before morphogenesis, the center (C; high future regeneration) of the wound has more RA than the edge (E; lower future regeneration) and accumulates more RA in response to Poly (I:C) (50 µl; 5 µg per mouse) in wild type (left) but not Tlr3^−/− mice (right) as measured by LC-MS/MS (right; n = 4 independent animals, *P < 0.05, paired Student t-test). White solid box indicates wounded area and red dashed lines signify center region of wound-healed skin. h Before morphogenesis, the center of the wound expresses more Aldh1a3, Krt15, and Krt19 than the edge in WT mice (n = 3 independent animals). i Increased RA pathway proteins in proteomic analysis of the C vs. E of the wounded skin prior to morphogenesis (n = 3 independent animals). * Indicates factors for RA pathway. Data are means ± SEM