SOCS2 Inhibits Mitochondrial Fatty Acid Oxidation via Suppressing LepR/JAK2/AMPK Signaling Pathway in Mouse Adipocytes

Oxid Med Cell Longev. 2020 Jul 13:2020:3742542. doi: 10.1155/2020/3742542. eCollection 2020.

Abstract

Suppressor of cytokine signaling 2 (SOCS2) plays an important role in fat deposition, skeletal muscle, central nervous system development, and mitochondria biogenesis. Nevertheless, the regulatory mechanisms of SOCS2 on mitochondrial fatty acid oxidation (FAO) remain unclear. Leptin could inhibit food intake and increase thermogenesis through leptin receptor (LepR), which was present in the hypothalamus and certain peripheral organs, including adipose tissue. With strong interest, we focused on the connection between leptin and SOCS2 and their effect on FAO in adipocytes. In our study, we found that the mRNA level of SOCS2 and the protein levels of PGC-1α, CPT-1b, FAT, and p-ACC were elevated by leptin in the inguinal adipose tissue of mice. On the contrary, the protein levels of FABP4, FATP1, and FAS were declined. The genes related to fatty acid oxidation such as PGC-1α, NRF-1, TFAM, CPT-1b, AOX1, COX2, and UCP2 were attenuated by SOCS2, but elevated by leptin. Moreover, fatty acid oxidation enzyme MCAD, LCAD, and Cyt C levels were reduced in response to SOCS2. These reductions correspond well with the reduced release of free fatty acid and the reduction of mitochondrial complexes I and III by SOCS2. Furthermore, JAK2/AMPK pathway-specific inhibitors could block the mitochondrial FAO; hence, this pathway was implied to have a potential impact on FAO. Together, these studies suggested that SOCS2 had a negative effect on mitochondrial fatty acid oxidation, and the LepR/JAK2/AMPK pathway played a crucial role in this process.

MeSH terms

  • AMP-Activated Protein Kinase Kinases
  • Adipocytes / metabolism*
  • Animals
  • Electron Transport Complex I / metabolism
  • Electron Transport Complex III / metabolism
  • Fatty Acids / metabolism*
  • Janus Kinase 2 / metabolism*
  • Leptin / metabolism
  • Leptin / pharmacology
  • Male
  • Mice
  • Mitochondria / drug effects
  • Mitochondria / metabolism*
  • Oxidation-Reduction
  • Protein Kinases / metabolism
  • Receptors, Leptin / metabolism*
  • Signal Transduction / drug effects
  • Suppressor of Cytokine Signaling Proteins / metabolism*

Substances

  • Fatty Acids
  • Leptin
  • Receptors, Leptin
  • Socs2 protein, mouse
  • Suppressor of Cytokine Signaling Proteins
  • leptin receptor, mouse
  • Protein Kinases
  • Jak2 protein, mouse
  • Janus Kinase 2
  • AMP-Activated Protein Kinase Kinases
  • Electron Transport Complex I
  • Electron Transport Complex III