2 research outputs found
Carbonylated Plasma Proteins As Potential Biomarkers of Obesity Induced Type 2 Diabetes Mellitus
Protein
carbonylation is a common nonenzymatic oxidative post-translational
modification, which is often considered as biomarker of oxidative
stress. Recent evidence links protein carbonylation also to obesity
and type 2 diabetes mellitus (T2DM), though the protein targets of
carbonylation in human plasma have not been identified. In this study,
we profiled carbonylated proteins in plasma samples obtained from
lean individuals and obese patients with or without T2DM. The plasma
samples were digested with trypsin, carbonyl groups were derivatized
with O-(biotinylcarbazoylmethyl)hydroxylamine, enriched by avidin
affinity chromatography, and analyzed by RPC-MS/MS. Signals of potentially
modified peptides were targeted in a second LC-MS/MS analysis to retrieve
the peptide sequence and the modified residues. A total of 158 unique
carbonylated proteins were identified, of which 52 were detected in
plasma samples of all three groups. Interestingly, 36 carbonylated
proteins were detected only in obese patients with T2DM, whereas 18
were detected in both nondiabetic groups. The carbonylated proteins
originated mostly from liver, plasma, platelet, and endothelium. Functionally,
they were mainly involved in cell adhesion, signaling, angiogenesis,
and cytoskeletal remodeling. Among the identified carbonylated proteins
were several candidates, such as VEGFR-2, MMP-1, argin, MKK4, and
compliment C5, already connected before to diabetes, obesity and metabolic
diseases
Defining the Human Adipose Tissue Proteome To Reveal Metabolic Alterations in Obesity
White adipose tissue (WAT) has a
major role in the progression
of obesity. Here, we combined data from RNA-Seq and antibody-based
immunohistochemistry to describe the normal physiology of human WAT
obtained from three female subjects and explored WAT-specific genes
by comparing WAT to 26 other major human tissues. Using the protein
evidence in WAT, we validated the content of a genome-scale metabolic
model for adipocytes. We employed this high-quality model for
the analysis of subcutaneous adipose tissue (SAT) gene expression
data obtained from subjects included in the Swedish Obese Subjects
Sib Pair study to reveal molecular differences between lean and obese
individuals. We integrated SAT gene expression and plasma metabolomics
data, investigated the contribution of the metabolic differences in
the mitochondria of SAT to the occurrence of obesity, and eventually
identified cytosolic branched-chain amino acid (BCAA) transaminase
1 as a potential target that can be used for drug development. We
observed decreased glutaminolysis and alterations in the BCAAs metabolism
in SAT of obese subjects compared to lean subjects. We also provided
mechanistic explanations for the changes in the plasma level of BCAAs,
glutamate, pyruvate, and α-ketoglutarate in obese subjects.
Finally, we validated a subset of our model-based predictions in 20
SAT samples obtained from 10 lean and 10 obese male and female subjects