Colin D. Funk

Bio: Colin D. Funk is an academic researcher from Queen's University. The author has contributed to research in topics: Leukotriene & Complementary DNA. The author has an hindex of 69, co-authored 189 publications receiving 19946 citations. Previous affiliations of Colin D. Funk include Washington University in St. Louis & Vanderbilt University Medical Center.

Prostaglandins and Leukotrienes: Advances in Eicosanoid Biology

Abstract: Prostaglandins and leukotrienes are potent eicosanoid lipid mediators derived from phospholipase-released arachidonic acid that are involved in numerous homeostatic biological functions and inflammation. They are generated by cyclooxygenase isozymes and 5-lipoxygenase, respectively, and their biosynthesis and actions are blocked by clinically relevant nonsteroidal anti-inflammatory drugs, the newer generation coxibs (selective inhibitors of cyclooxygenase-2), and leukotriene modifiers. The prime mode of prostaglandin and leukotriene action is through specific G protein-coupled receptors, many of which have been cloned recently, thus enabling specific receptor agonist and antagonist development. Important insights into the mechanisms of inflammatory responses, pain, and fever have been gleaned from our current understanding of eicosanoid biology.

Interleukin-4-dependent production of PPAR-γ ligands in macrophages by 12/15-lipoxygenase

Abstract: The peroxisome proliferator-activated receptor-gamma (PPAR-gamma) is a ligand-dependent nuclear receptor that has been implicated in the modulation of critical aspects of development and homeostasis, including adipocyte differentiation, glucose metabolism and macrophage development and function. PPAR-gamma is activated by a range of synthetic and naturally occurring substances, including antidiabetic thiazolidinediones, polyunsaturated fatty acids, 15-deoxy-delta prostaglandin J2 and components of oxidized low-density lipoprotein, such as 13-hydroxyoctadecadienoic acid (13-HODE) and 15-hydroxyeicosatetraenoic acid (15-HETE). However, the identities of endogenous ligands for PPAR-gamma and their means of production in vivo have not been established. In monocytes and macrophages, 13-HODE and 15-HETE can be generated from linoleic and arachidonic acids, respectively, by a 12/15-lipoxygenase that is upregulated by the TH2-derived cytokine interleukin-4. Here we show that interleukin-4 also induces the expression of PPAR-gamma and provide evidence that the coordinate induction of PPAR-gamma and 12/15-lipoxygenase mediates interleukin-4-dependent transcription of the CD36 gene in macrophages. These findings reveal a physiological role of 12/15-lipoxygenase in the generation of endogenous ligands for PPAR-gamma, and suggest a paradigm for the regulation of nuclear receptor function by cytokines.

Lipoxygenase and leukotriene pathways: biochemistry, biology, and roles in disease.

Abstract: 4. Biosynthesis of Leukotrienes 5869 4.1. Discovery of the Leukotriene Pathway and a Common Unstable Intermediate 5869 4.2. Conversion of Arachidonic Acid into Leukotriene A4 (LTA4) Is a Two-Step Concerted Reaction Catalyzed by a Single Lipoxygenase 5869 4.3. Structural Elucidation of Slow-Reacting Substance of Anaphylaxis, A Mixture of Leukotrienes 5870 5. Enzymes and Proteins in Leukotriene Biosynthesis 5870 5.1. Cytosolic Phospholipase A2α (cPLA2α) 5870 5.1.1. Molecular Properties and Regulation of cPLA2α 5870 5.1.2. Crystal Structure and Catalytic Mechanism of cPLA2α 5871 5.2. 5-Lipoxygenase (5-LO) 5871 5.2.1. Cellular Expression of 5-LO 5871 5.2.2. Regulation of 5-LO Gene (ALOX5) Transcription 5872 5.2.3. Naturally Occurring Mutations in the Gene Promoter of 5-LO 5872 5.2.4. Allosteric and Post-translational Regulation of 5-LO 5872 5.2.5. Structure function relationships in 5-LO 5872 5.2.6. Crystal Structure of 5-LO 5872 5.3. 5-Lipoxygenase-Activating Protein (FLAP) 5873 5.3.1. FLAP Is Critical for Cellular 5-LO Activity 5873 5.3.2. Effects of FLAP on Leukotriene Production 5873 5.3.3. FLAP Gene (ALOX5AP) and Regulation of Expression 5874 5.3.4. Crystal Structure of FLAP 5874 5.4. LTA4 Hydrolase 5874 5.4.1. LTA4 Hydrolase Is a Substrate-Selective and Suicide-Inactivated Epoxide Hydrolase 5874 5.4.2. LTA4 Hydrolase Is Bifunctional and Belongs to the M1 Family of Zinc Metallopeptidases 5874 5.4.3. LTA4 Hydrolase Cleaves the Chemotactic Pro-Gly-Pro, a Role for the Aminopeptidase Activity during Resolution of Inflammation 5875 5.4.4. Crystal Structure of LTA4 Hydrolase 5875 5.4.5. Mechanism of the Epoxide Hydrolase Reaction 5876 5.4.6. Mechanism of the Aminopeptidase Activity 5876 5.4.7. Two Catalytic Activities Exerted via Specific but Overlapping Active Sites 5877 5.5. LTC4 Synthase 5877 5.5.1. Molecular Properties of LTC4 Synthase 5877 5.5.2. LTC4 Synthase Is a Member of the MAPEG Superfamily of IntegralMembraneProteins 5877 5.5.3. Gene Structure and Regulation of LTC4 Synthase Expression 5877 5.5.4. Crystal Structure of LTC4 Synthase 5877 5.5.5. Catalytic Mechanism of LTC4 Synthase 5878 6. Intracellular Protein Trafficking and Compartmentalization of Leukotriene Biosynthesis 5878 6.1. Translocation of cPLA2α 5878 6.2. Translocation of 5-LO and Association with FLAP on the Nuclear Envelope 5879 6.2.1. 5-LO in the Nucleoplasm 5879 6.2.2. Organization of a Leukotriene Biosynthetic Complex in the Nuclear Membrane 5879 6.3. Leukotriene Biosynthesis in Lipid Bodies and Actions on Extracellular Granules 5879

Human platelet/erythroleukemia cell prostaglandin G/H synthase: cDNA cloning, expression, and gene chromosomal assignment.

Abstract: Platelets metabolize arachidonic acid to thromboxane A2, a potent platelet aggregator and vasoconstrictor compound. The first step of this transformation is catalyzed by prostaglandin (PG) G/H synthase, a target site for nonsteroidal antiinflammatory drugs. We have isolated the cDNA for both human platelet and human erythroleukemia cell PGG/H synthase using the polymerase chain reaction and conventional screening procedures. The cDNA encoding the full-length protein was expressed in COS-M6 cells. Microsomal fractions from transfected cells produced prostaglandin endoperoxide-derived products which were inhibited by indomethacin and aspirin. Mutagenesis of the serine residue at position 529, the putative aspirin acetylation site, to an asparagine reduced cyclooxygenase activity to barely detectable levels, an effect observed previously with the expressed sheep vesicular gland enzyme. Platelet-derived growth factor and phorbol ester differentially regulated the expression of PGG/H synthase mRNA levels in th...

In situ click chemistry generation of cyclooxygenase-2 inhibitors

Abstract: Cyclooxygenase-2 isozyme is a promising anti-inflammatory drug target, and overexpression of this enzyme is also associated with several cancers and neurodegenerative diseases. The amino-acid sequence and structural similarity between inducible cyclooxygenase-2 and housekeeping cyclooxygenase-1 isoforms present a significant challenge to design selective cyclooxygenase-2 inhibitors. Herein, we describe the use of the cyclooxygenase-2 active site as a reaction vessel for the in situ generation of its own highly specific inhibitors. Multi-component competitive-binding studies confirmed that the cyclooxygenase-2 isozyme can judiciously select most appropriate chemical building blocks from a pool of chemicals to build its own highly potent inhibitor. Herein, with the use of kinetic target-guided synthesis, also termed as in situ click chemistry, we describe the discovery of two highly potent and selective cyclooxygenase-2 isozyme inhibitors. The in vivo anti-inflammatory activity of these two novel small molecules is significantly higher than that of widely used selective cyclooxygenase-2 inhibitors. Traditional inflammation and pain relief drugs target both cyclooxygenase 1 and 2 (COX-1 and COX-2), causing severe side effects. Here, the authors use in situ click chemistry to develop COX-2 specific inhibitors with high in vivo anti-inflammatory activity.

Alternative activation of macrophages

Abstract: The classical pathway of interferon-gamma-dependent activation of macrophages by T helper 1 (T(H)1)-type responses is a well-established feature of cellular immunity to infection with intracellular pathogens, such as Mycobacterium tuberculosis and HIV. The concept of an alternative pathway of macrophage activation by the T(H)2-type cytokines interleukin-4 (IL-4) and IL-13 has gained credence in the past decade, to account for a distinctive macrophage phenotype that is consistent with a different role in humoral immunity and repair. In this review, I assess the evidence in favour of alternative macrophage activation in the light of macrophage heterogeneity, and define its limits and relevance to a range of immune and inflammatory conditions.

The Free Radical Theory of Aging Matures

Abstract: Beckman, Kenneth B., and Bruce N. Ames. The Free Radical Theory of Aging Matures. Physiol. Rev. 78: 547–581, 1998. — The free radical theory of aging, conceived in 1956, has turned 40 and is rapidl...

A new regulatory motif in cell-cycle control causing specific inhibition of cyclin D/CDK4

Abstract: The division cycle of eukaryotic cells is regulated by a family of protein kinases known as the cyclin-dependent kinases (CDKs). The sequential activation of individual members of this family and their consequent phosphorylation of critical substrates promotes orderly progression through the cell cycle. The complexes formed by CDK4 and the D-type cyclins have been strongly implicated in the control of cell proliferation during the G1 phase. CDK4 exists, in part, as a multi-protein complex with a D-type cyclin, proliferating cell nuclear antigen and a protein, p21 (refs 7-9). CDK4 associates separately with a protein of M(r) 16K, particularly in cells lacking a functional retinoblastoma protein. Here we report the isolation of a human p16 complementary DNA and demonstrate that p16 binds to CDK4 and inhibits the catalytic activity of the CDK4/cyclin D enzymes. p16 seems to act in a regulatory feedback circuit with CDK4, D-type cyclins and retinoblastoma protein.