Perilipin expression in human adipose tissue is elevated with obesity.
The perilipins are highly phosphorylated adipocyte proteins that are localized at the surface of the lipid droplet. With activation by protein kinase A, perilipins translocate away from the lipid droplet and allow hormone-sensitive lipase to hydrolyze the adipocyte triglycerides to release nonesterified fatty acids (NEFA). Because of the potential importance of adipocyte lipolysis to obesity and insulin resistance, we measured perilipin protein and mRNA levels in nondiabetic subjects with varying degrees of insulin resistance. By Northern and Western blotting, we could detect perilipin A, but not perilipin B. Perilipin A protein and mRNA levels were quantitated and were highly correlated with each other. There was a significant positive relationship between perilipin expression and obesity (r = 0.55; P < 0.01, perilipin mRNA vs. percent body fat). However, there was no significant relationship between perilipin expression and blood NEFA, nor was there a significant relationship between perilipin expression and insulin resistance, using the insulin sensitivity index derived from the iv glucose tolerance test with minimal modeling. In addition, there was no significant relationship between perilipin and adipocyte or systemic inflammatory markers, such as TNFalpha, IL-6, and adiponectin. Thus, perilipin was elevated in obese subjects, perhaps as a compensatory mechanism to limit basal lipolysis. However, there was no relationship between perilipin and insulin resistance.
Kern
Philip A
PA
Central Arkansas Veterans Healthcare System and Department of Medicine, Division of Endocrinology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA. kernphilipa@uams.edu
Di Gregorio
Gina
G
Lu
Tong
T
Rassouli
Negah
N
Ranganathan
Gouri
G
D000273:Adipose Tissue / Q000502:physiology*; D000328:Adult; D002352:Carrier Proteins; D005260:Female; D015870:Gene Expression; D006801:Humans; D007333:Insulin Resistance; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000378:metabolism / Q000503:physiopathology*; D000070778:Perilipin-1; D010750:Phosphoproteins / Q000235:genetics* / Q000378:metabolism; D010766:Phosphorylation; D012333:RNA, Messenger / Q000032:analysis; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics
D002352:Carrier Proteins; D000070778:Perilipin-1; D010750:Phosphoproteins; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha