title: No effect of weight loss on LINE-1 methylation levels in peripheral blood leukocytes from postmenopausal overweight women.
abstract: OBJECTIVE
  Obesity and weight-loss are associated with methylation patterns in specific genes, but their effect on Long Interspersed Nuclear Elements (LINE-1) methylation, a measure of global methylation is largely unknown.
  
  
  METHODS
  Three hundred overweight/obese post-menopausal women (50-75 years) were part of a completed, 1-year randomized controlled trial, comparing independent and combined effects of a reduced-calorie weight-loss diet, and exercise program, versus control. DNA was extracted from peripheral blood leukocytes collected at baseline and 12-months, and LINE-1 methylation analyzed by pyrosequencing. Mean changes between groups using generalized estimating equations and examined effects of weight-loss on LINE-1 methylation using stratified analyses (gained weight/no weight-loss [N = 84]; <5% [N = 45]; 5%-10% [N = 45]; >10% of baseline weight-loss [N = 126]) within each arm, adjusted by blood cell counts were compared. Associations between LINE-1 methylation and previously measured biomarkers, and anthropometrics were also examined.
  
  
  RESULTS
  No significant difference in LINE-1 methylation levels was detected in any intervention group versus controls. The magnitude of weight-loss was not associated with LINE-1 methylation at 12-months. There were no associations between baseline characteristics of participants, or previously measured biomarkers, and LINE-1 methylation.
  
  
  CONCLUSIONS
  Our results suggest that lifestyle changes sufficient to significantly reduce weight over 12-months may not change LINE-1 DNA methylation levels.
authors.affiliation: Epidemiology Program, Public Health Sciences, Fred Hutchinson Cancer Research Center, Seattle, WA, 98109, USA.
authors.forename: Catherine
authors.initials: C
authors.lastname: Duggan
authors.forename: Liren
authors.initials: L
authors.lastname: Xiao
authors.forename: Mary Beth
authors.initials: MB
authors.lastname: Terry
authors.forename: Anne
authors.initials: A
authors.lastname: McTiernan
mesh_terms: D000368:Aged; D001835:Body Weight; D019175:DNA Methylation; D002149:Energy Intake; D005081:Exercise Therapy; D005260:Female; D006801:Humans; D007962:Leukocytes / Q000378:metabolism*; D020084:Long Interspersed Nucleotide Elements / Q000235:genetics*; D008875:Middle Aged; D050177:Overweight / Q000097:blood / Q000235:genetics / Q000628:therapy*; D017698:Postmenopause / Q000097:blood / Q000235:genetics; D015431:Weight Loss / Q000235:genetics*; D061217:Weight Reduction Programs