Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
10803075 | Biochimica et Biophysica Acta (BBA) - Molecular Cell Research | 2008 | 10 Pages |
Abstract
Leptin, a hormone produced by adipose tissue, regulates energy balance in the hypothalamus and is involved in fertility, immune response and carcinogenesis. The existence of disorders related to leptin deficit and leptin overabundance calls for the development of drugs activating or inhibiting the leptin receptor (ObR). We synthesized four proposed receptor-binding leptin fragments (sites I, IIa and IIb, III), their reportedly antagonist analogs, and a peptide chimera composed of the two discontinuous site II arms. To assess the pharmacological utility of leptin fragments, we studied the peptides' ability to stimulate the growth of ObR-positive and ObR-negative cells. The combined site II construct and site III derivatives selectively reversed leptin-induced growth of ObR-positive cells at mid-nanomolar concentrations. However, these peptides appeared to be partial agonists/antagonists as they activated cell growth in the absence of exogenous leptin. A designer site III analog, featuring non-natural amino acids at terminal positions to decrease proteolysis and a blood-brain barrier (BBB) penetration-enhancing carbohydrate moiety, proved to be full agonist to ObR, i.e., stimulated proliferation of different ObR-positive but not ObR-negative cells in the presence or absence of leptin. This glycopeptide bound to isolated ObR on solid-phase assays and activated ERK-1/2 signaling in ObR-positive MCF-7 cells at 100-500Â nM concentrations. The glycopeptide was stable in mouse serum, readily crossed endothelial/astrocyte cell layers in a cellular BBB model, and was distributed into the brain of Balb/c mice after intraperitoneal administration. These characteristics suggest a potential pharmaceutical utility of the designer site III glycopeptide in leptin-deficient diseases.
Keywords
ATCCsodium dodecyl sulfate – polyacrylamide gel electrophoresisTris-buffered saline containing 0.1% Tween 20PI-3KObRFMOCERK 1/2GSKTBSTPKCPLCRP-HPLCTFASfMPBSTPeptidomimeticDMEMHRPCRHJanus kinaseBSADulbecco's modified Eagle's mediumbovine serum albuminSTATTrifluoroacetic acidSDS-PAGEanalysis of varianceANOVAEnzyme-linked immunosorbent assayELISAstandard errorCNSBlood–brain barrierBBBcentral nervous systemSignalingNeurohormoneGranulocyte-colony stimulating factorVascular endothelial growth factorVascular Endothelial Growth Factor (VEGF)G-CSFphospholipase Cphosphoinositide 3 kinaseMALDI-MSSignal transducer and activator of transcriptionAmerican Type Culture CollectionSerum-free mediumAntibodySerum stabilityHorseradish peroxidaseProtein kinase CJAKreversed-phase high performance liquid chromatographyextracellular signal-regulated kinases 1 and 2glycogen synthase kinaseLeptin receptor
Related Topics
Life Sciences
Biochemistry, Genetics and Molecular Biology
Biochemistry
Authors
Laszlo Jr., Marianna Terrasi, Sandra Cascio, Marco Cassone, Giovanni Abbadessa, Francesco De Pascali, Laura Scolaro, Daniel Knappe, Maciej Stawikowski, Predrag Cudic, John D. Wade, Ralf Hoffmann, Eva Surmacz,