Distinct isoforms of Nrf1 diversely regulate different subsets of its cognate target genes.

ABSTRACT: The single Nrf1 gene has capability to be differentially transcripted alongside with alternative mRNA-splicing and subsequent translation through different initiation signals so as to yield distinct lengths of polypeptide isoforms. Amongst them, three of the most representatives are Nrf1?, Nrf1? and Nrf1?, but the putative specific contribution of each isoform to regulating ARE-driven target genes remains unknown. To address this, we have herein established three cell lines on the base of the Flp-In T-REx system, which are allowed for the tetracycline-inducibly stable expression of Nrf1?, Nrf1? and Nrf1?. Consequently, the RNA-Sequencing results have demonstrated that a vast majority of differentially expressed genes (i.e. >90% DEGs detected) were dominantly up-regulated by Nrf1? and/or Nrf1? following induction by tetracycline. By contrast, the other DEGs regulated by Nrf1? were far less than those regulated by Nrf1?/? (i.e. ~11% of Nrf1? and ~7% of Nrf1?). However, further transcriptomic analysis revealed that the tetracycline-induced expression of Nrf1? significantly increased the percentage of down-regulated genes in total DEGs. These statistical data were further validated by quantitative real-time PCR. The experimental results indicate that distinct Nrf1 isoforms make diverse and even opposing contributions to regulating different subsets of target genes, such as those encoding 26S proteasomal subunits and others involved in various biological processes and functions. Collectively, Nrf1? acts as a major dominant-negative inhibitor competitively against Nrf1?/? activity, such that a number of DEGs regulated by Nrf1?/? are counteracted by Nrf1?.

SUBMITTER: Wang M 

PROVIDER: S-EPMC6393581 | biostudies-literature | 2019 Feb

REPOSITORIES: biostudies-literature