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Browsing by Author "Sussel, Lori"
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Item Regulation of β-cell death by ADP-ribosylhydrolase ARH3 via lipid signaling in insulitis(Springer Nature, 2024-02-21) Sarkar, Soumyadeep; Deiter, Cailin; Kyle, Jennifer E.; Guney, Michelle A.; Sarbaugh, Dylan; Yin, Ruichuan; Li, Xiangtang; Cui, Yi; Ramos‑Rodriguez, Mireia; Nicora, Carrie D.; Syed, Farooq; Juan‑Mateu, Jonas; Muralidharan, Charanya; Pasquali, Lorenzo; Evans‑Molina, Carmella; Eizirik, Decio L.; Webb‑Robertson, Bobbie‑Jo M.; Burnum‑Johnson, Kristin; Orr, Galya; Laskin, Julia; Metz, Thomas O.; Mirmira, Raghavendra G.; Sussel, Lori; Ansong, Charles; Nakayasu, Ernesto S.; Pediatrics, School of MedicineBackground: Lipids are regulators of insulitis and β-cell death in type 1 diabetes development, but the underlying mechanisms are poorly understood. Here, we investigated how the islet lipid composition and downstream signaling regulate β-cell death. Methods: We performed lipidomics using three models of insulitis: human islets and EndoC-βH1 β cells treated with the pro-inflammatory cytokines interlukine-1β and interferon-γ, and islets from pre-diabetic non-obese mice. We also performed mass spectrometry and fluorescence imaging to determine the localization of lipids and enzyme in islets. RNAi, apoptotic assay, and qPCR were performed to determine the role of a specific factor in lipid-mediated cytokine signaling. Results: Across all three models, lipidomic analyses showed a consistent increase of lysophosphatidylcholine species and phosphatidylcholines with polyunsaturated fatty acids and a reduction of triacylglycerol species. Imaging assays showed that phosphatidylcholines with polyunsaturated fatty acids and their hydrolyzing enzyme phospholipase PLA2G6 are enriched in islets. In downstream signaling, omega-3 fatty acids reduce cytokine-induced β-cell death by improving the expression of ADP-ribosylhydrolase ARH3. The mechanism involves omega-3 fatty acid-mediated reduction of the histone methylation polycomb complex PRC2 component Suz12, upregulating the expression of Arh3, which in turn decreases cell apoptosis. Conclusions: Our data provide insights into the change of lipidomics landscape in β cells during insulitis and identify a protective mechanism by omega-3 fatty acids.Item β-cell failure in type 2 diabetes: postulated mechanisms and prospects for prevention and treatment(Endocrine Society, 2014-06) Halban, Philippe A.; Polonsky, Kenneth S.; Bowden, Donald W.; Hawkins, Meredith A.; Ling, Charlotte; Mather, Kieren J.; Powers, Alvin C.; Rhodes, Christopher J.; Sussel, Lori; Weir, Gordon C.; Medicine, School of MedicineOBJECTIVE: This article examines the foundation of β-cell failure in type 2 diabetes (T2D) and suggests areas for future research on the underlying mechanisms that may lead to improved prevention and treatment. RESEARCH DESIGN AND METHODS: A group of experts participated in a conference on 14-16 October 2013 cosponsored by the Endocrine Society and the American Diabetes Association. A writing group prepared this summary and recommendations. RESULTS: The writing group based this article on conference presentations, discussion, and debate. Topics covered include genetic predisposition, foundations of β-cell failure, natural history of β-cell failure, and impact of therapeutic interventions. CONCLUSIONS: β-Cell failure is central to the development and progression of T2D. It antedates and predicts diabetes onset and progression, is in part genetically determined, and often can be identified with accuracy even though current tests are cumbersome and not well standardized. Multiple pathways underlie decreased β-cell function and mass, some of which may be shared and may also be a consequence of processes that initially caused dysfunction. Goals for future research include to 1) impact the natural history of β-cell failure; 2) identify and characterize genetic loci for T2D; 3) target β-cell signaling, metabolic, and genetic pathways to improve function/mass; 4) develop alternative sources of β-cells for cell-based therapy; 5) focus on metabolic environment to provide indirect benefit to β-cells; 6) improve understanding of the physiology of responses to bypass surgery; and 7) identify circulating factors and neuronal circuits underlying the axis of communication between the brain and β-cells.