Mitochondria are essential for synthesising ATP required for cellular metabolism. In response to changes in their cellular environment, mitochondria are able to alter their morphology and abundance through the balance of fusion and fission events. The aim of this study was to profile the expression of mitochondrial genes in the abdominal subcutaneous (AbSc) adipose tissue (AT) of lean, obese and Type 2 Diabetes Mellitus (T2DM) individuals and determine if bariatric surgery could modulate this gene expression.
Methods: AbSc AT from 12 Caucasian women, aged 3860 yrs with T2DM and BMI >35 kg/m2, who underwent restrictive or malabsorptive bariatric surgery was collected at the time of surgery and 30 days post-surgery by biopsy. AbSc AT from two control groups of non-diabetic females was also included in the study; overweight/obese: n=11 with BMI>27.5 kg/m2, aged 3560 and lean, n=6 with BMI<25.0 kg/m2 aged 4050. Expression of genes was measured by qRT-PCR.
Results: Overweight/obese individuals had a higher expression profile of both fission (DRP1; 3 fold and Fis1 1.3 fold) and fusion genes (MFN2; 1.5 fold, OPA1; 7 fold and FOXC2; 2 fold) compared to lean (n=11, P<0.05). With the exception of DRP1 and FOXC2 (2 fold higher and lower respectively), pre-bariatric T2DM subjects had a gene expression profile similar to that of lean individuals. Following bariatric surgery, expression of both fusion (FOXC2, MFN2 and OPA1) and fission genes (DRP1 and FIS1) (n=12, P<0.05) significantly increased.
Conclusions: This study highlights differences in the expression profile of genes regulating mitochondrial fusion and fission in AT between lean, obese and T2DM individuals. Expression of both genes regulating fusion and fission processes were higher in AT of obese compared to lean subjects. Following bariatric surgery, the expression of these genes was up-regulated in the AT. Future studies examining the effects of 15% weight-loss are planned.
Declaration of interest: There is no conflict of interest that could be perceived as prejudicing the impartiality of the research reported.
Funding: No specific grant from any funding agency in the public, commercial or not-for-profit sector.