| Description: | sirtuin1 (SIRT1), an NAD-dependent deacetylase, to be a direct target of miR-211 - the most significantly downregulated microRNA in lesional epidermis. Inhibition of SIRT1 with EX-527 downregulated keratin 10 and involucrin, suggesting that SIRT1 promotes keratinocyte differentiation. Overexpression of miR-211 mimic led to a significant increase in γ-H2AX positivity and cyclobutane pyrimidine dimer (CPD) formation, hallmarks of UVB-mediated DNA damage. These effects could be ameliorated by the addition of resveratrol, a SIRT1 activator. Furthermore, a long noncoding RNA, MALAT1, was identified as a negative upstream regulator of miR-211. Overexpression of MALAT1 resulted in increased expression of SIRT1 and a concomitant removal of UVB-induced CPDs in primary keratinocytes. |