Hui Gyu Park1, Matthew G Engel2, Kyle Vogt-Lowell3, Peter Lawrence4, Kumar S Kothapalli5, J Thomas Brenna6. 1. Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853, USA; Dell Pediatric Research Institute, Dell Medical School, The University of Texas at Austin, 1400 Barbara Jordan Blvd, Austin, TX 78723, USA. Electronic address: hi.park@austin.utexas.edu. 2. Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853, USA. Electronic address: mengel1@mail.einstein.yu.edu. 3. Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853, USA. Electronic address: kjv29@cornell.edu. 4. Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853, USA. Electronic address: pl79@ornell.edu. 5. Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853, USA; Dell Pediatric Research Institute, Dell Medical School, The University of Texas at Austin, 1400 Barbara Jordan Blvd, Austin, TX 78723, USA. Electronic address: kkothapalli@utexas.edu. 6. Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853, USA; Dell Pediatric Research Institute, Dell Medical School, The University of Texas at Austin, 1400 Barbara Jordan Blvd, Austin, TX 78723, USA. Electronic address: tbrenna@utexas.edu.
Abstract
INTRODUCTION: In mammals, FADS2 catalyzes "front-end" Δ4-, Δ6-, and Δ8-desaturation of fatty acyl chains, whereas FADS1 has Δ5-desaturase activity. Eighteen and 20-carbon precursors to highly unsaturated n-3 and n-6 fatty acids are the usual substrates for FADS1 and FADS2. Our main objective was to characterize the metabolic fate of oleic acid (OA) due to action of FADS gene products. METHODS: MCF-7 cells were stably transformed with either FADS1 or FADS2 or empty vector. A series of dose-response experiments were conducted with albumin-bound fatty acid substrates (18:1n-9 and 20:1n-9) provided in concentrations up to 100µM. Cells were harvested after 24h, after which FAME were prepared and analyzed by GC-FID and covalent adduct chemical ionization tandem mass spectrometry (CACI-MS/MS). RESULTS: When stably transformed cells were incubated with 18:1n-9, FADS1 and control cells elongated 18:1n-9 → 20:1n-9 (11-20:1), while FADS2 cells Δ6 desaturated, elongated, and then Δ5 desaturated via FADS1 coded activity leading to Mead acid, 9-18:1 → 6,9-18:2 → 8,11-20:2 (20:2n-9) → 6,8,11-20:3 (20:3n-9). Surprisingly, FADS1 cells Δ7 desaturated 11-20:1 → 7,11-20:2, the latter detected at low levels in control and FADS2 cells. Our results imply three pathways operate on 18:1n-9: 1) 18:1n-9 → 18:2n-9 → 20:2n-9 → 20:3n-9; 2) 18:1n-9 → 20:1n-9 → 20:2n-9 → 20:3n-9 and 3) 18:1n-9 → 20:1n-9 → 7,11-20:2. CONCLUSION: Alternative pathways for oleic acid metabolism exist depending on FADS2 or FADS1 activities, we present the first evidence of Δ7 desaturation via the FADS1 gene product.
INTRODUCTION: In mammals, FADS2 catalyzes "front-end" Δ4-, Δ6-, and Δ8-desaturation of fatty acyl chains, whereas FADS1 has Δ5-desaturase activity. Eighteen and 20-carbon precursors to highly unsaturated n-3 and n-6 fatty acids are the usual substrates for FADS1 and FADS2. Our main objective was to characterize the metabolic fate of oleic acid (OA) due to action of FADS gene products. METHODS:MCF-7 cells were stably transformed with either FADS1 or FADS2 or empty vector. A series of dose-response experiments were conducted with albumin-bound fatty acid substrates (18:1n-9 and 20:1n-9) provided in concentrations up to 100µM. Cells were harvested after 24h, after which FAME were prepared and analyzed by GC-FID and covalent adduct chemical ionization tandem mass spectrometry (CACI-MS/MS). RESULTS: When stably transformed cells were incubated with 18:1n-9, FADS1 and control cells elongated 18:1n-9 → 20:1n-9 (11-20:1), while FADS2 cells Δ6 desaturated, elongated, and then Δ5 desaturated via FADS1 coded activity leading to Mead acid, 9-18:1 → 6,9-18:2 → 8,11-20:2 (20:2n-9) → 6,8,11-20:3 (20:3n-9). Surprisingly, FADS1 cells Δ7 desaturated 11-20:1 → 7,11-20:2, the latter detected at low levels in control and FADS2 cells. Our results imply three pathways operate on 18:1n-9: 1) 18:1n-9 → 18:2n-9 → 20:2n-9 → 20:3n-9; 2) 18:1n-9 → 20:1n-9 → 20:2n-9 → 20:3n-9 and 3) 18:1n-9 → 20:1n-9 → 7,11-20:2. CONCLUSION: Alternative pathways for oleic acid metabolism exist depending on FADS2 or FADS1 activities, we present the first evidence of Δ7 desaturation via the FADS1 gene product.
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Authors: Kumar S D Kothapalli; Hui Gyu Park; Xiaoxian Guo; Xuepeng Sun; James Zou; Stephanie S Hyon; Xia Qin; Peter Lawrence; Rinat R Ran-Ressler; Ji Yao Zhang; Zhenglong Gu; J Thomas Brenna Journal: Prostaglandins Leukot Essent Fatty Acids Date: 2018-06-28 Impact factor: 4.006
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