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Sridharan GV, D'Alessandro M, Bale SS, Bhagat V, Gagnon H, Asara JM, Uygun K, Yarmush ML, Saeidi N. Multi-omic network-based interrogation of rat liver metabolism following gastric bypass surgery featuring SWATH proteomics. TECHNOLOGY 2017; 5:139-184. [PMID: 29780857 PMCID: PMC5956888 DOI: 10.1142/s233954781750008x] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/08/2023]
Abstract
Morbidly obese patients often elect for Roux-en-Y gastric bypass (RYGB), a form of bariatric surgery that triggers a remarkable 30% reduction in excess body weight and reversal of insulin resistance for those who are type II diabetic. A more complete understanding of the underlying molecular mechanisms that drive the complex metabolic reprogramming post-RYGB could lead to innovative non-invasive therapeutics that mimic the beneficial effects of the surgery, namely weight loss, achievement of glycemic control, or reversal of non-alcoholic steatohepatitis (NASH). To facilitate these discoveries, we hereby demonstrate the first multi-omic interrogation of a rodent RYGB model to reveal tissue-specific pathway modules implicated in the control of body weight regulation and energy homeostasis. In this study, we focus on and evaluate liver metabolism three months following RYGB in rats using both SWATH proteomics, a burgeoning label free approach using high resolution mass spectrometry to quantify protein levels in biological samples, as well as MRM metabolomics. The SWATH analysis enabled the quantification of 1378 proteins in liver tissue extracts, of which we report the significant down-regulation of Thrsp and Acot13 in RYGB as putative targets of lipid metabolism for weight loss. Furthermore, we develop a computational graph-based metabolic network module detection algorithm for the discovery of non-canonical pathways, or sub-networks, enriched with significantly elevated or depleted metabolites and proteins in RYGB-treated rat livers. The analysis revealed a network connection between the depleted protein Baat and the depleted metabolite taurine, corroborating the clinical observation that taurine-conjugated bile acid levels are perturbed post-RYGB.
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Affiliation(s)
- Gautham Vivek Sridharan
- Center for Engineering in Medicine, Harvard Medical School - Massachusetts General Hospital, 51 Blossom Street, Boston, MA 02114, USA
| | - Matthew D'Alessandro
- Center for Engineering in Medicine, Harvard Medical School - Massachusetts General Hospital, 51 Blossom Street, Boston, MA 02114, USA
| | - Shyam Sundhar Bale
- Center for Engineering in Medicine, Harvard Medical School - Massachusetts General Hospital, 51 Blossom Street, Boston, MA 02114, USA
| | - Vicky Bhagat
- Warren Alpert Medical School of Brown University, 222 Richmond St., Providence, RI 02903, USA
| | - Hugo Gagnon
- Phenoswitch Bioscience, 3001 12e Avenue N, Sherbrooke, QC J1H 5N4, Canada
| | - John M Asara
- Beth Israel Deaconness Medical Center, 3 Blackfan Circle Rm 425, Boston, MA 02115, USA
| | - Korkut Uygun
- Center for Engineering in Medicine, Harvard Medical School - Massachusetts General Hospital, 51 Blossom Street, Boston, MA 02114, USA
| | - Martin L Yarmush
- Center for Engineering in Medicine, Harvard Medical School - Massachusetts General Hospital, 51 Blossom Street, Boston, MA 02114, USA
| | - Nima Saeidi
- Center for Engineering in Medicine, Harvard Medical School - Massachusetts General Hospital, 51 Blossom Street, Boston, MA 02114, USA
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McIntosh AL, Senthivinayagam S, Moon KC, Gupta S, Lwande JS, Murphy CC, Storey SM, Atshaves BP. Direct interaction of Plin2 with lipids on the surface of lipid droplets: a live cell FRET analysis. Am J Physiol Cell Physiol 2012; 303:C728-42. [PMID: 22744009 DOI: 10.1152/ajpcell.00448.2011] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Abstract
Despite increasing awareness of the health risks associated with excess lipid storage in cells and tissues, knowledge of events governing lipid exchange at the surface of lipid droplets remains unclear. To address this issue, fluorescence resonance energy transfer (FRET) was performed to examine live cell interactions of Plin2 with lipids involved in maintaining lipid droplet structure and function. FRET efficiencies (E) between CFP-labeled Plin2 and fluorescently labeled phosphatidylcholine, sphingomyelin, stearic acid, and cholesterol were quantitated on a pixel-by-pixel basis to generate FRET image maps that specified areas with high E (>60%) in lipid droplets. The mean E and the distance R between the probes indicated a high yield of energy transfer and demonstrated molecular distances on the order of 44-57 Å, in keeping with direct molecular contact. In contrast, FRET between CFP-Plin2 and Nile red was not detected, indicating that the CFP-Plin2/Nile red interaction was beyond FRET proximity (>100 Å). An examination of the effect of Plin2 on cellular metabolism revealed that triacylglycerol, fatty acid, and cholesteryl ester content increased while diacylglycerol remained constant in CFP-Plin2-overexpressing cells. Total phospholipids also increased, reflecting increased phosphatidylcholine and sphingomyelin. Consistent with these results, expression levels of enzymes involved in triacylglycerol, cholesteryl ester, and phospholipid synthesis were significantly upregulated in CFP-Plin2-expressing cells while those associated with lipolysis either decreased or were unaffected. Taken together, these data show for the first time that Plin2 interacts directly with lipids on the surface of lipid droplets and influences levels of key enzymes and lipids involved in maintaining lipid droplet structure and function.
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Affiliation(s)
- Avery L McIntosh
- Dept. of Biochemistry and Molecular Biology, Michigan State Univ., East Lansing, MI 48824, USA
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