title: A fragment of the Escherichia coli ClpB heat-shock protein is a micromolar melanocortin 1 receptor agonist.
abstract: The melanocortin system consists of five receptor subtypes (MC1-5R), endogenous agonists derived from the proopiomelanocortin gene transcript, and the antagonists agouti and agouti-related protein. The Escherichia coli heat shock protein ClpB has previously been described as an antigen mimetic to the endogenous melanocortin agonist α-MSH. Herein, we investigated if a fragment of the ClpB protein could directly signal through the melanocortin receptors. We synthesized a complementary fragment of the ClpB protein that partially aligned with α-MSH. Pharmacological assessment of this fragment resulted in no antagonist activity at the MC3R or the MC4R and no agonist activity at the MC4R. Partial receptor activation was observed for the MC3R and MC5R at 100 μM concentrations. This fragment was shown to be a full micromolar MC1R agonist and may serve as a template for future research into selective MC1R ligands.
authors.affiliation: Department of Medicinal Chemistry, University of Minnesota, 308 Harvard Street SE, Minneapolis, MN 55455, USA.
authors.forename: Mark D
authors.initials: MD
authors.lastname: Ericson
authors.affiliation: Department of Medicinal Chemistry, University of Minnesota, 308 Harvard Street SE, Minneapolis, MN 55455, USA.
authors.forename: Sathya M
authors.initials: SM
authors.lastname: Schnell
authors.affiliation: Department of Medicinal Chemistry, University of Minnesota, 308 Harvard Street SE, Minneapolis, MN 55455, USA.
authors.forename: Katie T
authors.initials: KT
authors.lastname: Freeman
authors.affiliation: Department of Medicinal Chemistry, University of Minnesota, 308 Harvard Street SE, Minneapolis, MN 55455, USA. Electronic address: chaskell@umn.edu.
authors.forename: Carrie
authors.initials: C
authors.lastname: Haskell-Luevano
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D049071:Endopeptidase Clp; D004926:Escherichia coli; D029968:Escherichia coli Proteins / Q000138:chemical synthesis / Q000494:pharmacology*; D057809:HEK293 Cells; D006360:Heat-Shock Proteins / Q000138:chemical synthesis / Q000494:pharmacology*; D006801:Humans; D008024:Ligands; D051379:Mice; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000494:pharmacology*; D044102:Receptor, Melanocortin, Type 1 / Q000819:agonists*
chemical_list: C000608576:ClpB(535-548); D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins; D008024:Ligands; D010446:Peptide Fragments; D044102:Receptor, Melanocortin, Type 1; D049071:Endopeptidase Clp; C069775:ClpB protein, E coli
keywords: AlphaScreen® cAMP assay; ClpB heat shock protein; Melanocortin receptors; NDP-MSH; α-MSH