Genomes and Genes
Molecular mechanism of omega-3 response
Principal Investigator: JAMES T BRENNA
Abstract: DESCRIPTION (provided by applicant): Omega-3 (?3 or n-3) long chain polyunsaturated fatty acids (LCPUFA, e.g., 22:6n-3, 20:5n-3) are among the most popular dietary supplements used by Americans. Understanding inter-individual response variation requires elucidation of the underlying pathways and the influence of genotypes. LCPUFA biosynthesis is limited by desaturase activity encoded by the fatty acid desaturase gene cluster (FADS1-3, 11q12-13.1). FADS intronic and intergenic SNPs are disproportionately identified as significant in genetic studies (e.g. GWAS). In recent years we showed that all the FADS genes have conserved, highly expressed, and phylogenetically conserved alternative transcripts (AT). A newly described FADS1 AT has desaturase function and new siRNA data show that a specific splicing factor (SF), PTB (hnRNP I) modulates FADS AT abundance. In early 2012, we generated the first Fads3-/- (null) mouse to investigate the as-yet-unknown function of this extensively alternatively spliced gene. AT represent a novel, essential paradigm for omega-3 metabolic control mediated in non-coding regions. Present knowledge of regulatory mechanisms neglecting AT are necessarily incomplete because >95% of human genes produce AT, including the FADS genes. The overall goal is to discover the regulation and function of FADS AT and some of their genetic control via mechanistic investigation. Hypothesis 1: FADS AT are modulated by dietary PUFA and by hormones via splicing factors (SF) in a manner consistent with enhanced catalysis (e.g. FADS1AT1) or inhibition (e.g. FADS3 AT) of desaturation. Hypothesis 2: FADS AT modulation is related to SNPs and haplotypes via splicing factors. Specific Aim 1. Define the transcription start sites (TSS) and UTR of FADS CS and AT. (a) Determine the promoters and full length open reading frames (ORFs) of FADS CS and AT with RNA-Seq using human liver. (b) Determine FADS transcript modulation by ratios of dietary PUFA in mice and by hormones in human cells, thereby establishing AT as intermediate biomarkers for LCPUFA biosynthesis. (c) Develop and implement RNAi of splicing factors and inhibition of their phosphorylation to investigate SF modulation of FADS transcripts, and fatty acid desaturation and composition. Specific Aim 2. Discovery of FADS AT function(s) and modulation. (a) Based on RNA-Seq and RNAi results: (i) Transfect human cells to test for activation or inhibition by specific AT. (ii) Construct vectors for functional studies in human cels, using full length ORF. (b) Characterize the overt and molecular/biochemical phenotype of Fads3 null mice. (c) Investigate the prevalence of human SNPs and haplotypes related to PUFA biosynthesis. Relevance to human health. Understanding of FADS AT regulation, function, and influence on LCPUFA bio- synthesis will enable mechanistic evaluation of interindividual variability in LCPUFA biosynthesis. Human genetic variation and metabolic conditions responsive to omega-3 LCPUFA supplementation will be identified.
Funding Period: 2013-01-01 - 2017-12-31
more information: NIH RePORT
- Effects of low-dose aspirin and fish oil on platelet function and NF-kappaB in adults with diabetes mellitusRobert C Block
Department of Public Health Sciences, The University of Rochester School of Medicine and Dentistry, Rochester, New York, USA
Prostaglandins Leukot Essent Fatty Acids 89:9-18. 2013..Many diabetics are insensitive to aspirin's platelet anti-aggregation effects. The possible modulating effects of co-administration of aspirin and fish oil in subjects with diabetes are poorly characterized...
- Dietary arachidonic acid and docosahexaenoic acid regulate liver fatty acid desaturase (FADS) alternative transcript expression in suckling pigletsVasuki Wijendran
Department of Pediatrics, Massachusetts General Hospital for Children, Harvard Medical School, Boston, MA, USA
Prostaglandins Leukot Essent Fatty Acids 89:345-50. 2013..Further, the data suggest that Fads3 AT7 may have functional significance when dietary supply of ARA and DHA are low during early development. ..
- Effect of sex hormones on n-3 polyunsaturated fatty acid biosynthesis in HepG2 cells and in human primary hepatocytesCharlene M Sibbons
Academic Unit of Human Development and Health, Faculty of Medicine, University of Southampton, Southampton, UK
Prostaglandins Leukot Essent Fatty Acids 90:47-54. 2014..These findings show that progesterone increases n-3 PUFA biosynthesis by up-regulating the mRNA expression of genes involved in this pathway, possibly via changes in the epigenetic regulation of FADS2. ..