Differentially regulated miRNAs in skin fibroblasts with constitutively active Nrf2

The NRF2 transcription factor is a key regulator of the cellular antioxidant response, and pharmacological NRF2 activation is a promising strategy for the prevention of age-related diseases. Here we show, however, that genetic activation of Nrf2 in skin fibroblasts leads to the production of a matrisome, which is similar to aged skin and characterized by reduced synthesis and deposition of selected matrix proteins, including the major skin collagens. Mechanistically, the production of an aging matrisome results from Nrf2-mediated overexpression of microRNAs (miRs), which directly suppress collagen expression independently of myofibroblast differentiation. This is functionally important, as Nrf2 activation in fibroblasts caused structural abnormalities of the dermal ECM and increased the susceptibility to skin tearing, similar to aged skin. Activation of endogenous NRF2 was observed in human skin from elderly individuals in vitro and in vivo. These data implicate a key role for activated NRF2 in controlling age-related molecular and biomechanical skin alterations. Overall design: Primary fibroblasts were isolated and cultured from the skin of newborn transgenic mice with Cre-recombinase expressed in fibroblasts (Col1a2Cre). Fibroblasts from 3 mice with Cre plus a constitutively active Nrf2 (caNrf2) mutant and 3 mice with Cre only (ctrl) were used. Fibroblasts were allowed to proliferate in culture for 6 days to allow for sufficient numbers for miRNA sequencing. Total RNA was isolated from cells followed by miRNA-seq analysis.