Long isoforms of NRF1 negatively regulate adipogenesis via suppression of PPAR gamma expression

• Authors: Peng Xue, China Medical University; Yongyong Hou, China Medical University; Zhuo Zuo, China Medical University; Zhendi Wang, China Medical University; Suping Ren, China Medical University; Jian Dong, ScitoVation LLC; Jingqi Fu, China Medical University; Huihui Wang, China Medical University; Melvin E. Andersen, ScitoVation LLC; Qiang Zhang, Emory University; Yuanyuan Xu, China Medical University; Jingbo Pi, China Medical University
• Journal Title: Redox Biology
• Volume: Volume 30
• Publisher: Elsevier | 2020-02-01, Pages 101414-101414
• Type of Work: Article | Final Publisher PDF
• Publisher DOI: http://doi.org/10.1016/j.redox.2019.101414
• Subjects: Biology, Genetics; Biology, Molecular; Chemistry, Biochemistry
• Keywords: Science & Technology; Life Sciences & Biomedicine; Biochemistry & Molecular Biology; NRF1; Adipogenesis; PPAR gamma; White adipocytes; Bzip transcription factor; Endoplasmic reticulum stress; Antioxidant response; Gene expression; Embryonic; Proteasome; Deficiency; Mouse; Beta; Dimerization

Abstract

Nuclear factor erythroid 2-related factor 1 (NRF1), a ubiquitously expressed CNC-bZIP transcription factor, plays a critical role in white adipocyte (WAC) biology, whereas the underlying mechanisms remain unknown. The mouse Nrf1 gene is transcribed in a number of alternatively spliced forms, resulting in two long protein isoforms (L-NRF1) containing 741 and 742 amino acids (aa) and multiple short isoforms (S-NRF1). Our previous study found that adipocyte-specific knockout of Nrf1 [Nrf1(f)-KO] in mice disturbs the expression of lipolytic genes in adipocytes, leading to adipocyte hypertrophy followed by inflammation, pyroptosis and insulin resistance. In the present study, we found that the stromal vascular fraction (SVF) cells isolated from white adipose tissues (WAT) of Nrf1(f)-KO mice display augmented adipogenesis showing elevated mRNA and protein expression of adipogenic markers and lipid accumulation. In 3T3-L1 cells, stable knockdown (KD) of all or long isoforms of Nrf1 (termed as A-Nrf1-KD and L-Nrf1-KD, respectively) using lentiviral shRNAs resulted in enhanced and accelerated adipogenic differentiation. Conversely, overexpression of L-NRF1-741, but not any of the S-NRF1, substantially attenuated adipogenesis in 3T3-L1 cells. These findings indicate that L-NRF1 might serve as a critical negative regulator of adipogenesis. Mechanistic investigation revealed that L-NRF1 may negatively regulates the transcription of peroxisome proliferator-activated receptor γ (PPARγ), in particular the master regulator of adipogenesis PPARγ2. Taken all together, the findings in the present study provide further evidence for a novel role of NRF1 beyond its participation in cellular antioxidant response and suggest that L-NRF1 is a negative regulator of PPARγ2 expression and thereby can suppress adipogenesis.