Important mitochondrial proteins in human omental adipose tissue show reduced expression in obesity

• We studied mitochondrial protein expression in omental adipocytes of obese patients.
• Mass spectrometry was combined with immunological quantification.
• 76 proteins were found to be differentially expressed in obese vs. normal subjects.
• Four important mitochondrial proteins showed an inverse association with BMI.
• This may explain reduced mitochondrial function in omental adipose tissue in obesity.

Impaired mitochondrial function is important in obesity and the development of insulin resistance and diabetes. The aim of this study was to identify human adipocyte-derived mitochondrial proteins associated with obesity. Mitochondrial proteins from 20 abdominal omental adipose tissue biopsies (13 obese and 7 control subjects) were separated by anion-exchange chromatography coupled to SDS-PAGE. Protein contents were compared and identified by MALDI-TOF-TOF mass spectrometry. Proteins of interest were validated, verified and quantified using immuno dot blot assays in a total of 76 mitochondrial preparations from both obese and non-obese patients. Mass spectrometric comparison of 20 mitochondrial proteomes yielded 62 proteins that were differentially expressed in adipose tissue of obese subjects. The immunological quantification of 12 mitochondrial proteins from 76 omental adipose tissue biopsies revealed four proteins, citrate synthase, HADHA, LETM1 and mitofilin inversely being associated with BMI, and mitofilin being inversely correlated with gender.Biological significanceThe finding that obese human subjects have reduced levels of important mitochondrial proteins in adipocytes of omental adipose tissue as compared to non-obese controls gives new insights in the impairment of mitochondrial function in this specialized compartment of human adipose tissue in obesity and may eventually lead to the definition of valuable obesity markers.

Diagram showing the experimental steps starting with the isolation of adipocytes from human omental adipose tissue to mass spectrometric analysis of mitochondrial proteins.Figure optionsDownload high-quality image (87 K)Download as PowerPoint slide