The polypyrimidine tract binding protein regulates desaturase alternative splicing and PUFA composition. 2011

Holly T Reardon, and Woo Jung Park, and Jimmy Zhang, and Peter Lawrence, and Kumar S D Kothapalli, and J Thomas Brenna
Division of Nutritional Sciences, Cornell University, Ithaca, NY 14853.

The Δ6 desaturase, encoded by FADS2, plays a crucial role in omega-3 and omega-6 fatty acid synthesis. These fatty acids are essential components of the central nervous system, and they act as precursors for eicosanoid signaling molecules and as direct modulators of gene expression. The polypyrimidine tract binding protein (PTB or hnRNP I) is a splicing factor that regulates alternative pre-mRNA splicing. Here, PTB is shown to bind an exonic splicing silencer element and repress alternative splicing of FADS2 into FADS2 AT1. PTB and FADS2AT1 were inversely correlated in neonatal baboon tissues, implicating PTB as a major regulator of tissue-specific FADS2 splicing. In HepG2 cells, PTB knockdown modulated alternative splicing of FADS2, as well as FADS3, a putative desaturase of unknown function. Omega-3 fatty acids decreased by nearly one half relative to omega-6 fatty acids in PTB knockdown cells compared with controls, with a particularly strong decrease in eicosapentaenoic acid (EPA) concentration and its ratio to arachidonic acid (ARA). This is a rare demonstration of a mechanism specifically altering the cellular omega-3 to omega-6 fatty acid ratio without any change in diet/media. These findings reveal a novel role for PTB, regulating availability of membrane components and eicosanoid precursors for cell signaling.

UI MeSH Term Description Entries
D010215 Papio A genus of the subfamily CERCOPITHECINAE, family CERCOPITHECIDAE, consisting of five named species: PAPIO URSINUS (chacma baboon), PAPIO CYNOCEPHALUS (yellow baboon), PAPIO PAPIO (western baboon), PAPIO ANUBIS (or olive baboon), and PAPIO HAMADRYAS (hamadryas baboon). Members of the Papio genus inhabit open woodland, savannahs, grassland, and rocky hill country. Some authors consider MANDRILLUS a subgenus of Papio. Baboons,Baboons, Savanna,Savanna Baboons,Baboon,Baboon, Savanna,Papios,Savanna Baboon
D011485 Protein Binding The process in which substances, either endogenous or exogenous, bind to proteins, peptides, enzymes, protein precursors, or allied compounds. Specific protein-binding measures are often used as assays in diagnostic assessments. Plasma Protein Binding Capacity,Binding, Protein
D005091 Exons The parts of a transcript of a split GENE remaining after the INTRONS are removed. They are spliced together to become a MESSENGER RNA or other functional RNA. Mini-Exon,Exon,Mini Exon,Mini-Exons
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000818 Animals Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA. Animal,Metazoa,Animalia
D015525 Fatty Acids, Omega-3 A group of unsaturated fatty acids occurring mainly in fish oils, with three double bonds at particular positions in the hydrocarbon chain. N-3 Fatty Acid,Omega-3 Fatty Acid,Omega-3 Fatty Acids,n-3 Fatty Acids,n-3 Oil,n3 Oil,Omega 3 Fatty Acids,n-3 Oils,n-3 PUFA,n-3 Polyunsaturated Fatty Acid,n3 Fatty Acid,n3 Oils,n3 PUFA,n3 Polyunsaturated Fatty Acid,Acid, N-3 Fatty,Acid, Omega-3 Fatty,Fatty Acid, N-3,Fatty Acid, Omega-3,Fatty Acid, n3,N 3 Fatty Acid,Oil, n-3,Oil, n3,Omega 3 Fatty Acid,PUFA, n-3,PUFA, n3,n 3 Fatty Acids,n 3 Oil,n 3 Oils,n 3 PUFA,n 3 Polyunsaturated Fatty Acid
D015854 Up-Regulation A positive regulatory effect on physiological processes at the molecular, cellular, or systemic level. At the molecular level, the major regulatory sites include membrane receptors, genes (GENE EXPRESSION REGULATION), mRNAs (RNA, MESSENGER), and proteins. Receptor Up-Regulation,Upregulation,Up-Regulation (Physiology),Up Regulation
D017398 Alternative Splicing A process whereby multiple RNA transcripts are generated from a single gene. Alternative splicing involves the splicing together of other possible sets of EXONS during the processing of some, but not all, transcripts of the gene. Thus a particular exon may be connected to any one of several alternative exons to form a mature RNA. The alternative forms of mature MESSENGER RNA produce PROTEIN ISOFORMS in which one part of the isoforms is common while the other parts are different. RNA Splicing, Alternative,Splicing, Alternative,Alternate Splicing,Nested Transcripts,Alternate Splicings,Alternative RNA Splicing,Alternative RNA Splicings,Alternative Splicings,Nested Transcript,RNA Splicings, Alternative,Splicing, Alternate,Splicing, Alternative RNA,Splicings, Alternate,Splicings, Alternative,Splicings, Alternative RNA,Transcript, Nested,Transcripts, Nested
D043371 Fatty Acids, Omega-6 FATTY ACIDS which have the first unsaturated bond in the sixth position from the omega carbon. A typical American diet tends to contain substantially more omega-6 than OMEGA-3 FATTY ACIDS. N-6 Fatty Acid,Omega-6 Fatty Acid,Omega-6 Fatty Acids,Fatty Acids, Omega 6,N-6 Fatty Acids,Acid, N-6 Fatty,Acid, Omega-6 Fatty,Acids, N-6 Fatty,Acids, Omega-6 Fatty,Fatty Acid, N-6,Fatty Acid, Omega-6,Fatty Acids, N-6,N 6 Fatty Acid,N 6 Fatty Acids,Omega 6 Fatty Acid,Omega 6 Fatty Acids
D044943 Fatty Acid Desaturases A family of enzymes that catalyze the stereoselective, regioselective, or chemoselective syn-dehydrogenation reactions. They function by a mechanism that is linked directly to reduction of molecular OXYGEN. Acyl CoA Desaturase,Enoyl CoA Reductase,Fatty Acid Desaturase,Fatty Acid Desaturating Enzymes,Acyl CoA Desaturases,Enoyl CoA Reductases,Acid Desaturase, Fatty,CoA Desaturase, Acyl,CoA Reductase, Enoyl,Desaturase, Acyl CoA,Desaturase, Fatty Acid,Desaturases, Fatty Acid,Reductase, Enoyl CoA,Reductases, Enoyl CoA

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