Lipocalin Laboratory

Members

• Hermann Krabichler technician
• Petra Merschak technician
• Anna Moussavi, student
• Alexandra Pipal Ph.D.
• Bernhard Redl Ph.D., Associate Prof.
• Tamara Staudinger, student
• Linda Teufel M.Sc., Ph.D., Postdoc
• Hans Zwerger, student

Projects

Structure and Function of Lipocalins and their Cellular Receptors

(project leader: Bernhard Redl)

Our group investigates structural and functional features of human lipocalins. The protein superfamily of ãlipocalinsÒ consists of small, mainly secretory proteins defined on the basis of conserved amino acid sequence motifs and their common structure. Functionally, they were found to be important extracellular carriers of lipophilic compounds in vertebrates, invertebrates, plants, and bacteria. There is increasing evidence that this group of proteins is involved in a variety of physiological processes including retinoid, fatty acid, and pheromone signaling; immunomodulation; inflammation; detoxification; modulation of growth and metabolism; tissue development; apoptosis; and even behavior processes. Whereas the structural basis of lipocalin-ligand binding is now well understood, there is a major lack of knowledge regarding the mechanisms by which lipocalins exert their biological effects. This is mainly due to the fact that only limited data are available on lipocalin receptors and lipocalin-receptor interactions, although it is well accepted that many, if not all, of these proteins are able to bind to specific cell receptors.

Current research projects of our lab focus on the following subjects: Identification of cellular lipocalin receptors, characterization of the molecular mechanism of the receptor-ligand interaction and the biological processes beyond receptor binding. - Evaluation of novel functions of lipocalins in innate immunity and allergy.

Methods

• Standard molecular biological techniques (cloning of genes, expression of recombinant proteins in bacterial and eucaryotic cells, reporter gene assays).
• Phage display technology.
• Standard biochemical techniques (protein purification, ligand binding assays).
• Standard methods in molecular biology, e.g. molecular cloning techniques; RT-PCR; site-directed mutagenesis; expression of homologous and heterologous recombinant proteins in filamentous fungi and mammalian cells, in insect cells by the Baculovirus-expression system.
• Biochemical methods: purification of recombinant proteins, chromatography, metabolic labeling.
• Immunological methods: immunoprecipitation, ELISA, Western blot technique, fluorescence staining.

Selected Publications

1. Redl B., Holzfeind P. and Lottspeich F. (1992) cDNA cloning and sequencing reveals human tear prealbumin to be a member of the lipophilic-ligand carrier protein superfamily. J. Biol. Chem. 267, 20282-20287.
2. Redl B., Wojnar P., Ellemunter H. and Feichtinger H. (1998) Identification of a lipocalin in mucosal glands of the human tracheobronchial tree and its enhanced secretion in cystic fibrosis. Lab. Invest. 78, 1121-1129.
3. Redl B., Merschak P., Abt B. and Wojnar P. (1999) Phage display reveals a novel interaction of human lipocalin LCN1 and thioredoxin which is relevant for ligand binding. FEBS Lett. 460, 182-186.
4. Redl B. (2000) Human Tear Lipocalin. Biochim. Biophys. Acta 1482, 241-248.
5. Lechner M., Wojnar P. and Redl B. (2001) Human tear lipocalin acts as an oxidative-stress-induced scavenger of potentially harmful lipid peroxidation products in a cell culture system. Biochem J., 356, 129-135.
6. Wojnar P., Lechner M., Merschak P. and Redl B. (2001) Molecular cloning of a novel Lipocalin-1 interacting human cell membrane receptor (LIMR) using phage-display. J. Biol. Chem., 276(23), 20206-20212.
7. Wojnar P., van't Hof W., Merschak P., Lechner M. and Redl B. (2001) The N-terminal part of recombinant human Tear Lipocalin/von Ebner's gland protein confers cysteine proteinase inhibition depending on the presence of the entire cystatin-like motifs. Biol. Chem., 382(10), 1515-1520.
8. Wojnar P., Dirnhofer S., Ladurner P., Berger P. and Redl B. (2002) Human Lipocalin-1, a potential physiological scavenger of lipophilic compounds, is produced by corticotrophs of the pituitary gland. J. Histochem. Cytochem., 50(3), 433-435.
9. Petra Wojnar, Markus Lechner, and Bernhard Redl (2003). Antisense downregulation of the lipocalin-interacting-membrane-receptor expression inhibits cellular internalization of Lipocalin-1 in human NT2 cells. J. Biol. Chem, 278, 16209-16215.
10. Breustedt D.A., Korndoerfer I.P., Redl B. and Skerra A. (2005) The 1.8 A crystal structure of human tear lipocalin reveals an extended branched cavity with capacity for multiple ligands. J. Biol. Chem. 280, 484-493
11. Fluckinger M., Haas H., Merschak P., Glasgow BJ. and Redl B. (2004) Human Tear Lipocalin exhibits antimicrobial activity by scavenging of microbial siderophores. Antimicrob. Agents Chemoth. 48, 3367-3372.
12. Saaren-Sepp H., Jauhiainen M., Tervo T., Redl B., Kinnunen P. and Holopainen J. (2005). Interaction of purified Tear Lipocalin with lipid membranes. Invest. Ophth.Vis. Sci., 46, 3649-3656
13. Burke B.J., Redondo C., Redl B. and Findlay J.B.C. (2006). Lipocalin Receptors: Into the Spotlight. In: Lipocalins, ed. Akerstroem B., Borregaard N., Flower, D.R. and Salier J-P., pp. 157-166, Landes Bioscience, USA
14. Gasymov O.K., Abduragimov A.R., Merschak P., Redl B. and Glasgow B.J. (2007) Oligomeric State of Lipocalin-1 (LCN-1) by Multiangle Laser Light Scattering and Fluorescence Anisotropy Decay. BBA-Proteins and Proteomics 1774, 1307-1315
15. Fluckinger M., Merschak P., Hermann M., Haertle T. and Redl B. (2008) Lipocalin-interacting-membrane-receptor (LIMR) mediates cellular internalization of beta-lactoglobulin. BBA-Biomembranes 1787, 342-347.