OBJECTIVE: FSP27 KO mice showed enhanced expression of mitochondrial genes, 
increased mitochondrial activity and smaller lipid droplets. Here, we aimed to 
investigate lipid droplet protein (CIDEC/FSP27 and perilipinA (PLIN1)) gene 
expression in human adipose tissue in association with obesity, insulin 
resistance and mitochondrial gene expression.
DESIGN AND SUBJECTS: In cohort 1, CIDEC/FSP27, PLIN1, adipogenic (FASN, ACACA, 
PPARG, GLUT4) and mitochondrial (PPARGC1A, PPARGC1B, TFAM, MT-CO3) gene 
expression were analyzed in 171 adipose tissue samples (88 visceral adipose 
tissue (VAT) and 83 subcutaneous adipose tissue (SAT) depots) and in a time 
course experiment in human subcutaneous and visceral preadipocytes using 
real-time PCR. In cohort 2, the effects of bariatric surgery-induced weight loss 
were also evaluated in six caucasian morbidly obese women. Additionally, in 
cohort 2 FSP27 and PLIN1 protein levels were measured using western blotting.
RESULTS: CIDEC/FSP27 (1.03±0.52 vs 0.49±0.23 relative gene expression unit 
(R.U.), P<0.0001) and PLIN1 (1.32±0.82 vs 0.63±0.42 R.U., P<0.0001) gene were 
significantly more expressed in SAT than in VAT. In VAT, CIDEC/FSP27 and PLIN1 
gene expression decreased with body mass index, percent fat mass, fasting 
glucose, fasting insulin, HOMA and were positively associated with adipogenic 
(PPARG, GLUT4, FASN and ACACA) and mitochondrial biogenesis (PPARGC1A, PPARGC1B, 
TFAM and MT-CO3)-related genes. Mitochondrial gene expression increased during 
adipocyte differentiation in parallel to FSP27 and PLIN1 and other adipogenic 
genes. After bariatric surgery-induced weight loss, PLIN1 and CIDEC/FSP27 gene 
and protein expression in SAT increased significantly in parallel to adipogenic 
and mitochondrial genes.
CONCLUSION: These findings suggest a positive functional interaction between 
CIDEC/FSP27, PLIN1 and mitochondrial biogenesis-related genes in human adipose 
tissue.