A novel crosstalk between Nrf2 and Smad2/3 bridged by two nuanced Keap1 isoforms with their divergent effects on these distinct family transcription factors
- Free Radic Biol Med. 2024 Jan 17:S0891-5849(24)00025-X. doi: 10.1016/j.freeradbiomed.2024.01.025.
- 1. College of Bioengineering and Graduate School, Chongqing University, No. 174 Shazheng Street, Shapingba District, Chongqing 40044, China; Chongqing University Jiangjin Hospital, School of Medicine, Chongqing University, No. 725 Jiangzhou Avenue, Dingshan Street, Jiangjin District, Chongqing 402262, China; The Laboratory of Cell Biochemistry and Topogenetic Regulation, College of Bioengineering and Faculty of Medical Sciences, Chongqing University, No. 174 Shazheng Street, Shapingba District, Chongqing 40044, China.
- 2. College of Bioengineering and Graduate School, Chongqing University, No. 174 Shazheng Street, Shapingba District, Chongqing 40044, China; The Laboratory of Cell Biochemistry and Topogenetic Regulation, College of Bioengineering and Faculty of Medical Sciences, Chongqing University, No. 174 Shazheng Street, Shapingba District, Chongqing 40044, China.
- 3. Chongqing Key Laboratory of Medicinal Resources in the Three Gorges Reservoir Region, School of Biological and Chemical Engineering, Chongqing University of Education, Chongqing 400067, China.
- 4. Laboratory of Neuroscience, Institute of Cognitive Neuroscience and School of Pharmacy, University College London, 29-39 Brunswick Square, London, WC1N 1AX, England, United Kingdom.
- 5. College of Bioengineering and Graduate School, Chongqing University, No. 174 Shazheng Street, Shapingba District, Chongqing 40044, China.
- 6. Chongqing University Jiangjin Hospital, School of Medicine, Chongqing University, No. 725 Jiangzhou Avenue, Dingshan Street, Jiangjin District, Chongqing 402262, China; The Laboratory of Cell Biochemistry and Topogenetic Regulation, College of Bioengineering and Faculty of Medical Sciences, Chongqing University, No. 174 Shazheng Street, Shapingba District, Chongqing 40044, China. Electronic address: [email protected].
The Keap1-Nrf2 signalling to transcriptionally regulate antioxidant response element (ARE)-driven target genes has been accepted as key redox-sensitive pathway governing a vast variety of cellular stresses during healthy survival and disease development. Herein, we identified two nuanced isoforms α and β of Keap1 in HepG2 cells, arising from its first and another in-frame translation starting codons, respectively. In identifying those differential expression genes monitored by Keap1α and/or Keap1β, an unusual interaction of Keap1 with SMAD2/3 was discovered by parsing transcriptome Sequencing, Keap1-interacting protein profiling and relevant immunoprecipitation data. Further examination validated that SMAD2/3 enable physical interaction with Keap1, as well as its isoforms α and β, by both EDGETSD and DLG motifs in the linker regions between their MH1 and MH2 domains, such that the stability of SMAD2/3 and its transcriptional activity are enhanced with their prolonged half-lives and relevant signalling responses from the cytoplasmic to nuclear compartments. The activation of SMAD2/3 by Keap1, Keap1α or Keap1β was much likely contributable to a coordinative or another competitive effect of Nrf2, particularly in distinct Keap1-based cellular responses to its cognate growth factor (i.e. TGF-β1) or redox stress (e.g. stimulated by tBHQ and DTT). Overall, this discovery presents a novel functional bridge crossing the Keap1-Nrf2 redox signalling and the TGF-β1-Smad2/3 pathways so as to coordinately regulate the healthy growth and development.