title: Fine-tuned iron availability is essential to achieve optimal adipocyte differentiation and mitochondrial biogenesis.
abstract: OBJECTIVE
  Adipose tissue from obese and insulin-resistant individuals showed altered expression of several iron-related genes in a recent study, suggesting that iron might have an important role in adipogenesis. To investigate this possible role, we aimed to characterise the effects of iron on adipocyte differentiation.
  
  
  METHODS
  Intracellular iron deficiency was achieved using two independent approaches: deferoxamine administration (20 and 100 μmol/l) and transferrin knockdown (TF KD). The effects of added FeSO4, holo-transferrin and palmitate were studied during human and 3T3-L1 adipocyte differentiation. Finally, the relationship between iron-related and mitochondrial-related genes was investigated in human adipose tissue.
  
  
  RESULTS
  Most adipose tissue iron-related genes were predominantly expressed in adipocytes compared with stromal vascular cells. Of note, transferrin gene and protein expression increased significantly during adipocyte differentiation. Both deferoxamine and TF KD severely blunted adipocyte differentiation in parallel with increased inflammatory mRNAs. These effects were reversed in a dose-dependent manner after iron supplementation. Palmitate administration also led to a state of functional intracellular iron deficiency, with decreased Tf gene expression and iron uptake during adipocyte differentiation, which was reversed with transferrin co-treatment. On the other hand, iron in excess impaired differentiation, but this antiadipogenic effect was less pronounced than under iron chelation. Of interest, expression of several genes involved in mitochondrial biogenesis occurred in parallel with expression of iron-related genes both during adipogenesis and in human adipose tissue.
  
  
  CONCLUSIONS
  Precise and fine-tuned iron availability is essential to achieve optimal adipocyte differentiation, possibly modulating adipocyte mitochondrial biogenesis.
authors: Department of Diabetes, Endocrinology and Nutrition, Institut d'Investigació Biomèdica de Girona (IdIBGi), Hospital of Girona 'Dr Josep Trueta', Girona, Spain.
authors: José María
authors: JM
authors: Moreno-Navarrete
authors: Francisco
authors: F
authors: Ortega
authors: María
authors: M
authors: Moreno
authors: Wifredo
authors: W
authors: Ricart
authors: José Manuel
authors: JM
authors: Fernández-Real
mesh_terms: D041721:3T3-L1 Cells; D017667:Adipocytes / Q000166:cytology* / Q000378:metabolism; D050156:Adipogenesis / Q000235:genetics / Q000502:physiology; D000273:Adipose Tissue / Q000378:metabolism*; D000818:Animals; D002454:Cell Differentiation / Q000235:genetics / Q000502:physiology; D002478:Cells, Cultured; D006801:Humans; D051379:Mice; D063269:Mitochondrial Turnover / Q000235:genetics / Q000502:physiology*