Lipidomics in Cell Regulation

1. Lipidomics in Cell Regulation Lars I Hellgren Associate Professor February 24th, 2012

2. Learning objectives Afterthislectureyoushouldbeable to: -Describe the major types of lipids - Describe the mainfunctions of lipids in the cell - Describe at leasttwomechanisms of action by whichlipidsregulatecell-metabolism or cell- development

3. Outline • Why must webother- Relation betweenlipid – patterns and human disease • What is a lipid– Differerentlipid types. • How doeslipidsaffectcellularregulation? • Effects in membranes • Direct effects on enzymes • Effectsthroughlipid receptors • Lipidpathways Whatdetermines the lipidome? • Interpretting the lipidome

4. Lipids and Human Health • Cardiovasculardiseases– Stronglylinked to levels of differentfattyacids and lipidmetabolism in the arteries, in the blood and in the heart • Insulin resistance/ Type-2 diabetes – Stronglylinked to concentration of certainlipids and lipidmetabolism in skeletal muscles, adipose tissue, the liver and insulin producingb-cells in the pancreas • Severalrheumaticdiseases– Stronglylinked to the concentration of certainfattyacids • Many cancer forms – Stronglylinked to the metabolism of sphingolipids, such as ceramide and sphingosine-1-P

5. Lipids – someexamples Phosphoglyceride Fattyacids Triacylglycerol R = fattyacids Ganglioside GM2

6. So, what´s a lipid ? Someexamples from the literature • ”Naturallyoccurringcompounds, which have in common a readysolubility in organic solvents and lowsolubiltiy in water” • ”Hydrophobic or amphipathic small moleculesthatmayoriginateentirely or in part by carbanion-basedcondensations of thioesters (fattyacids, polyketides, etc.) and/or by carbocation-basedcondensations of isoprene units (prenols, sterols, etc.)” Fahyet al. (J. Lipid Res., 46, 839-862 (2005)) • ”Lipidsarefattyacids and their derivatives, and substancesrelatedbiosynthetically or functionally to thesecompounds. ” Bill Cristie on www.lipidlibrary.co.uk

7. Lipids – someexamples Glycerophospholipids Fattyacids Triacylglycerol R = fattyacids Ganglioside GM2

8. Major Types of Lipids Glycerophospholipids Fattyacids Sphingolipids Sterols Sphingosine Ceramide cholesterol Sphingomyelin cholesterolesters Glycosphingolipids

9. Lipidstructures – Fattyacids • Most abundant: C14 – C24 • 0 – 6 double bonds • saturated, monounsaturated, polyunsaturated • Only minute amounts are free. • Normally constitutents of other lipids; triacylglycerols, phosphoglycerides, sphingolipidsetc • Certain FA are important regulators of gene-transcription in glucose and lipid metabolism • FA – metabolites are important signalling molecules involved in: • Induction and resultion of inflammation (f. ex. prostaglandins and resolvins) • Appetite regulation (endocannabinoids) C16:0 C18:1 Arachidonicacid (C20:4; n-6) Docosahexaenoicacid (DHA) (C20:4; n-6)

10. Lipidstructures – Glycerophospholipids • Major lipid component of membranes • Varying polar headgroups and fatty acid chains • Variation in headgroup and fatty acid chains alter their properties  altered membrane properties • Some phosphoglyceride are directly modulating enzyme activity, f ex phosphpatidylserine and Proteinkinase C of the classical type

11. Glycerophospholipids-variation in structure 30 – 35 differentfattyacidsarecommonlyidentified in glycerophospholipids

12. Lipidfunctions in cellbiology The biologicalmembrane • Defines the cell and the cell organelles • Semipermeable – efflux and influx of polar molecules are controlled • Is the basis for energy metabolism – proton-gradients • Ensure a stable cellular environment • Provides a 2-D space for efficient chemical reaction • The lipids creates an optimal environment for protein function in the membrane  More than 300 lipid species are found in the plasma membrane

13. Lipidfunctions in cellbiology Regulation of gene-transcription • Transcriptionalregulation of genes in glucose and fat metabolismarepartlycontrolled by lipidlevelsthroughlipid-activatedtranscription factors Example of lipidregulatedtranscription factors: The family of PeroxisomeProliferatorActivated- Receptors (PPAR) Binding of polyunsaturatedfattyacids, or structuresderived from polyunsaturatedfattyacidsarerequired for theiractivation. Picture from Cuzzòcrea , 2006

14. Lipidfunctions in cellbiology Lipidsignalling – Lipidsareimportantintra- and extracellularsignallingmolecules Prostaglandin and leukotriensynthesis (Eicosanoids) Somelipidsignallingmolecules • Eicosanoids • Resolvins, Neuroprotectins • Diacylglycerol • Ceramide • Sphingosine-1-phosphate • Ceramide-1-phosphate • Phosphoinosotides • etc, etc Inflammation Vasoconstriction Gasticmucosalsecretion …. Plateletaggregation bloodclotting ….

15. Lipidfunctions in cellbiology Lipidsignalling Example2: The ceramide / Sphingosine-1-P Rheostat Sphingosine Ceramide: Cell cycle arrest Terminal differentation Apoptosis Sphingosine-1-phosphate: Cell proliferation Prevent differentiation Sphingomyelin: Membrane lipid

16. Lipidfunctions in cellbiology Lipidsignallingthroughdirectlipid protein interactions Examples: Protein kinase C – activated by diacylglycerol or ceramide (some types) Phosphoinositide Dependent Kinase– Activatedtrough binding to the membranelipidphosphatidylinositol-tris- phosphate Clinicalimplications:

17. Insulin receptor IRS-1 PDK-1 PKB PI-3 K Effects of DAG and ceramide on insulin signalling DAG PKCθ Serine phosphorylation inhibits the interaction with the insulin-receptor Phosphorylation threonin34 inhibits the binding to PIP3 in the plasma membrane Dephosphorylation of serin473 deactivates PKB Ceramid PKC PP2A Powell et al (2003). Mol. Cell Biology. 23:7794-7808; Stratford et al (2004) J. Biol . Chem. 279:36608-15; Kim et al (2004) J. Clinical Inv. 114:823-827

18. Fatty acid metabolism Acetyl-CoA ACC FFA FFA Mitochondria FAS b-oxidation ACS CPT I Acyl-CoA GPAT Acyl-Carnithin Palmitoyl-CoA Lyso-phosphatidate Palmital SPT Phosphatidate Sphingosine 1-P Diacylglycerol Phosphoglycerides Sphingosine FFA Ceramide DGAT Neutral glycolipids Sphingomyelin Gangliosides Triacylglycerol Lars I. Hellgren SBE-Symposium 2008

19. Lipidomics Lipidcomposition Transcriptomes of lipidmetabolism Pathwayfluxes ”Downstream” effects of lipidchanges Data integration Models of howlipidomic alterations areinvolved in diseasepathologies New therapies

20. The human plasma lipidome Quehenberger O et al. J. Lipid Res. 2010;51:3299-3305

21. Examples on lipids, genes and pathway data http://www.lipidmaps.org