title: FNDC5 could be regulated by leptin in adipose tissue.
abstract: BACKGROUND
  Irisin activates the thermogenic function in adipose tissues. However, little is known on the association between human irisin and different cardiometabolic risk factors. We analyse the influence of morbid obesity on irisin levels and its relation with leptin and different cardiovascular risk factors.
  
  
  METHODS
  We measured the serum irisin level and the fibronectin type III domain containing 5 (FNDC5) expression in adipose tissue from 33 morbidly obese subjects and 12 nonobese subjects. We also studied the effect of leptin on FNDC5 expression.
  
  
  RESULTS
  Serum irisin was higher in the nonobese subjects than in morbidly obese subjects, both before (P = 0·043) and after bariatric surgery (P = 0·042). The variable that best explained the serum irisin levels in a multiple linear regression model was the waist-to-hip ratio (WHR) (R(2) = 0·201) (Beta = -0·357, P = 0·046). Those morbidly obese subjects with android-type obesity had lower serum irisin levels than those with gynecoid-type obesity, both before (P = 0·027) and after bariatric surgery (P = 0·006). Only the percentage change in WHR was associated with serum irisin levels after bariatric surgery (r = -0·529, P = 0·005). FNDC5 expression levels in subcutaneous adipose tissue (SAT) were higher in the nonobese than in the morbidly obese subjects (P = 0·042). In SAT explants from nonobese subjects, leptin (20 and 150 ng/mL) produced a decrease in FNDC5 expression (P = 0·009 and P = 0·037, respectively).
  
  
  CONCLUSIONS
  We showed decreased serum irisin levels in morbidly obese subjects, related mainly to WHR. FNDC5 expression could be regulated by leptin.
authors.affiliation: Unidad de Gestión Clínica de Endocrinología y Nutrición, Instituto de Investigaciones Biomédicas de Málaga (IBIMA), Hospital Regional Universitario, Málaga, Spain.
authors.forename: Carolina
authors.initials: C
authors.lastname: Gutierrez-Repiso
authors.forename: Sara
authors.initials: S
authors.lastname: Garcia-Serrano
authors.forename: Francisca
authors.initials: F
authors.lastname: Rodriguez-Pacheco
authors.forename: Eva
authors.initials: E
authors.lastname: Garcia-Escobar
authors.forename: Juan J
authors.initials: JJ
authors.lastname: Haro-Mora
authors.forename: Juan
authors.initials: J
authors.lastname: Garcia-Arnes
authors.forename: Sergio
authors.initials: S
authors.lastname: Valdes
authors.forename: Montserrat
authors.initials: M
authors.lastname: Gonzalo
authors.forename: Federico
authors.initials: F
authors.lastname: Soriguer
authors.forename: Francisco J
authors.initials: FJ
authors.lastname: Moreno-Ruiz
authors.forename: Alberto
authors.initials: A
authors.lastname: Rodriguez-Cañete
authors.forename: Abelardo
authors.initials: A
authors.lastname: Martinez-Ferriz
authors.forename: Julio S
authors.initials: JS
authors.lastname: Santoyo
authors.forename: Vidal
authors.initials: V
authors.lastname: Perez-Valero
authors.forename: Eduardo
authors.initials: E
authors.lastname: Garcia-Fuentes
mesh_terms: D000328:Adult; D015536:Down-Regulation; D005260:Female; D005353:Fibronectins / Q000378:metabolism*; D044385:GTP-Binding Protein alpha Subunits / Q000378:metabolism; D006801:Humans; D050152:Intra-Abdominal Fat / Q000737:chemistry*; D020738:Leptin / Q000502:physiology*; D008297:Male; D009767:Obesity, Morbid / Q000097:blood*; D012333:RNA, Messenger / Q000378:metabolism; D050151:Subcutaneous Fat / Q000737:chemistry*; D049629:Waist-Hip Ratio
chemical_list: C577593:FNDC5 protein, human; D005353:Fibronectins; D044385:GTP-Binding Protein alpha Subunits; D020738:Leptin; D012333:RNA, Messenger
keywords: Adipose tissue; FNDC5; PCG1-α; irisin; leptin; morbid obesity; waist-to-hip ratio