Figure 3.
δ-Opioid receptor (DOPr) overexpression and activation impairs keratinocyte differentiation. Cells were grown to confluence and differentiation induced by removal of growth factors under the influence of methionine5 (Met)-enkephalin for up to 10 days. Differentiation marker gene expression was analyzed by quantitative real-time PCR. Data are represented after normalization to RPL13a expression as mean ±SEM (n=3 keratin intermediate filament (KRT10), n=4 KRT1, n=5 involucrin (IVL), loricrin (LOR), and filaggrin (FLG)). Expression levels of (a) KRT10, (b) KRT1, (c) IVL, (d) LOR, and (e) FLG are shown after normalization to vehicle-treated control cells. Two-way analysis of variance, ***P<0.001, **P<0.01, and *P<0.05. (f, g) Whole-cell lysates from confluent cultures (day 0) and day 1, 4, and 7 of differentiation with and without addition of 100 nM Met-enkephalin (f) or SNC80 (g) were analyzed by immunoblot for KRT10 and KRT1 expression, with equal loading verified by glyceraldehyde-3-phosphate dehydrogenase (GAPDH). GFP, green fluorescent protein.