MicroRNAs regulate human adipocyte lipolysis: effects of miR-145 are linked to TNF-α

PLoS One. 2014 Jan 24;9(1):e86800. doi: 10.1371/journal.pone.0086800. eCollection 2014.

Abstract

MicroRNAs (miRNAs) are small non-coding RNAs that regulate gene expression and have multiple effects in various tissues including adipose inflammation, a condition characterized by increased local release of the pro-lipolytic cytokine tumor necrosis factor-alpha (TNF-α). Whether miRNAs regulate adipocyte lipolysis is unknown. We set out to determine whether miRNAs affect adipocyte lipolysis in human fat cells. To this end, eleven miRNAs known to be present in human adipose tissue were over-expressed in human in vitro differentiated adipocytes followed by assessments of TNF-α and glycerol levels in conditioned media after 48 h. Three miRNAs (miR-145, -26a and let-7d) modulated both parameters in parallel. However, while miR-26a and let-7d decreased, miR-145 increased both glycerol release and TNF-α secretion. Further studies were focused therefore on miR-145 since this was the only stimulator of lipolysis and TNF-α secretion. Time-course analysis demonstrated that miR-145 over-expression up-regulated TNF-α expression/secretion followed by increased glycerol release. Increase in TNF-α production by miR-145 was mediated via activation of p65, a member of the NF-κB complex. In addition, miR-145 down-regulated the expression of the protease ADAM17, resulting in an increased fraction of membrane bound TNF-α, which is the more biologically active form of TNF-α. MiR-145 overexpression also increased the phosphorylation of activating serine residues in hormone sensitive lipase and decreased the mRNA expression of phosphodiesterase 3B, effects which are also observed upon TNF-α treatment in human adipocytes. We conclude that miR-145 regulates adipocyte lipolysis via multiple mechanisms involving increased production and processing of TNF-α in fat cells.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ADAM Proteins / antagonists & inhibitors
  • ADAM Proteins / genetics
  • ADAM Proteins / metabolism
  • ADAM17 Protein
  • Adipocytes / cytology
  • Adipocytes / drug effects
  • Adipocytes / metabolism*
  • Adipose Tissue / cytology
  • Adipose Tissue / drug effects
  • Adipose Tissue / metabolism
  • Cyclic Nucleotide Phosphodiesterases, Type 3 / genetics
  • Cyclic Nucleotide Phosphodiesterases, Type 3 / metabolism
  • Female
  • Gene Expression Regulation*
  • Glycerol / metabolism
  • Humans
  • Lipolysis / genetics*
  • Male
  • MicroRNAs / genetics*
  • MicroRNAs / metabolism
  • Primary Cell Culture
  • Signal Transduction
  • Sterol Esterase / genetics
  • Sterol Esterase / metabolism
  • Transcription Factor RelA / agonists
  • Transcription Factor RelA / genetics
  • Transcription Factor RelA / metabolism
  • Transfection
  • Tumor Necrosis Factor-alpha / genetics*
  • Tumor Necrosis Factor-alpha / metabolism
  • Tumor Necrosis Factor-alpha / pharmacology

Substances

  • MIRN145 microRNA, human
  • MIRN26A microRNA, human
  • MicroRNAs
  • Transcription Factor RelA
  • Tumor Necrosis Factor-alpha
  • mirnlet7 microRNA, human
  • Sterol Esterase
  • Cyclic Nucleotide Phosphodiesterases, Type 3
  • ADAM Proteins
  • ADAM17 Protein
  • ADAM17 protein, human
  • Glycerol

Grants and funding

This work was supported by several grants from Swedish Research Council, The Swedish Diabetes Foundation, the Diabetes Program at Karolinska Institute, the Swedish Cancer Foundation, Diabetes Wellness, the Swedish Society of Medicine, Tore Nilsson Foundation, Foundation for Gamla Tjänarinnor and EASD/Lilly program and Novo Nordisk Foundation. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.