Upregulation of Mlxipl induced by cJun in the spinal dorsal horn after peripheral nerve injury counteracts mechanical allodynia by inhibiting neuroinflammation

Aging (Albany NY). 2020 Jun 9;12(11):11004-11024. doi: 10.18632/aging.103313. Epub 2020 Jun 9.

Abstract

Mlxipl regulates glucose metabolism, lipogenesis and tumorigenesis and has a wide-ranging impact on human health and disease. However, the role of Mlxipl in neuropathic pain remains unknown. In this study, we found that Mlxipl was increased in the ipsilateral L4-L6 spinal dorsal horn after Spared Nerve Injury surgery. Knockdown of Mlxipl in the ipsilateral L4-L6 spinal dorsal horn by intraspinal microinjection aggravated Spared Nerve Injury-induced mechanical allodynia and inflammation in the spinal dorsal horn, on the contrary, overexpression of Mlxipl inhibited mechanical allodynia and inflammation. Subsequently, the rat Mlxipl promoter was analyzed using bioinformatics methods to predict the upstream transcription factor cJun. Luciferase assays and ChIP-qPCR confirmed that cJun bound to the promoter of Mlxipl and enhanced its expression. Finally, we demonstrated that Mlxipl inhibited the inflammatory responses of lipopolysaccharide-induced microglia and that Mlxipl was regulated by the transcription factor cJun. These findings suggested that cJun-induced Mlxipl upregulation in the spinal dorsal horn after peripheral nerve injury provided a protective mechanism for the development and progression of neuropathic pain by inhibiting microglial-derived neuroinflammation. Targeting Mlxipl in the spinal dorsal horn might represent an effective strategy for the treatment of neuropathic pain.

Keywords: Mlxipl; cJun; mechanical allodynia; microglia; neuroinflammation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / genetics
  • Basic Helix-Loop-Helix Leucine Zipper Transcription Factors / metabolism*
  • Gene Expression Regulation
  • Gene Knockdown Techniques
  • Hyperalgesia / metabolism*
  • Male
  • Microglia / metabolism
  • Neuralgia / metabolism*
  • Peripheral Nerve Injuries / metabolism*
  • Promoter Regions, Genetic
  • Proto-Oncogene Proteins c-jun / genetics
  • Proto-Oncogene Proteins c-jun / metabolism*
  • Rats
  • Rats, Sprague-Dawley
  • Spinal Cord Dorsal Horn / drug effects
  • Spinal Cord Dorsal Horn / metabolism*
  • Up-Regulation

Substances

  • Basic Helix-Loop-Helix Leucine Zipper Transcription Factors
  • Mlxipl protein, rat
  • Proto-Oncogene Proteins c-jun