![]() Fatty liver disease is increasingly considered a major threat to metabolic health in overweight populations.ĭespite the general appreciation of the unhealthy consequences of a fatty liver, the factors that contribute to hepatic fat accumulation in humans are still far from understood and mainly rely on studies performed in animal models. Furthermore, a fatty liver also increases the risk for hypertriglyceridemia, cardiovascular disease, and nonalcoholic steatohepatitis (NASH) ( 5– 7). In fact, after the introduction and the widespread use of this technique, evidence has accumulated that, in humans, increased intrahepatic lipid content (IHL content) is a very common condition, which strongly increases the risk to develop type 2 diabetes mellitus (T2DM) ( 3, 4). Proton magnetic resonance spectroscopy ( 1H-MRS) has offered the opportunity to noninvasively detect intraorgan lipids in nonadipose tissue, such as liver and muscle, so-called ectopic fat ( 1, 2). The ge-HSQC can be used to noninvasively reveal the contribution of dietary fat to the development of hepatic steatosis over time. Thus, a substantial part of the liver fat can originate directly from storage of meal-derived fat. Approximately 1.5% of the tracer was retained in the liver after 6 hours, and retention was similar in both groups ( P = 0.92). Postprandial retention of orally administered 13C-labeled fatty acids was significant ( P < 0.01). Here, we investigated the use of 1-dimensional gradient enhanced heteronuclear single quantum coherence (ge-HSQC) spectroscopy for the in vivo detection of hepatic 1H-lipid signals after a single high-fat meal with 13C-labeled fatty acids in 5 lean and 6 obese subjects. Successful implementation of such methodology, however, is challenging due to low sensitivity of 13C-magnetic resonance spectroscopy ( 13C-MRS). The low (1.1%) natural abundance (NA) of carbon-13 ( 13C) allows use of 13C-enriched lipids for in vivo MR studies. Dietary fat retention is one of the pathways that may lead to fatty liver. Although extensively studied in a preclinical setting, the lack of noninvasive methodologies hampers our understanding of which pathways promote hepatic fat accumulation in humans. Fatty liver increases the risk for insulin resistance, cardiovascular disease, and nonalcoholic steatohepatitis (NASH). © 2022 Federation of European Biochemical Societies.The prevalence of fatty liver reaches alarming proportions. NMR T-cell activation conformational change molecular dynamics protein-protein interaction. Notably, in addition to its major conformation, we detected a minor conformation of nSH2 in the CD28 bound state that may explain the allosteric conformational change in the BC loop. Our MD simulations largely explained the NMR results and the structural dynamics of nSH2 and CD28 in both bound and unbound states. Further, using 19 F- and 31 P-labelled CD28 phosphopeptide, we analysed the structural dynamics of CD28 and demonstrated that the aromatic ring of the pY residue fluctuated between multiple conformations upon nSH2 binding. The conformational stabilisation of the C-terminal region correlated with the regulation of PI3K catalytic function. NMR relaxation experiments showed a conformational exchange associated with CD28 binding in these regions. Chemical shift perturbation experiments revealed allosteric changes at the BC loop and the C-terminal region of nSH2 upon CD28 binding. First, we assigned the backbone signals of nSH2 on 1 H- 15 N heteronuclear single quantum coherence spectra in the absence or presence of the CD28 phosphopeptide, SDpYMNMTPRRPG. ![]() Here, we analysed the interaction between the N-terminal SH2 domain (nSH2) of the regulatory subunit in phosphoinositide 3-kinase (PI3K) and the cytoplasmic region of the T-cell co-receptor, CD28, using NMR and molecular dynamics (MD) simulations. Src homology 2 (SH2) domains are commonly found in adapter proteins involved in signal transduction and specifically bind to consensus motifs of proteins containing phosphorylated tyrosine (pY). Protein conformational changes with fluctuations are fundamental aspects of protein-protein interactions (PPIs) understanding these motions is required for the rational design of PPI-regulating compounds. ![]()
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