Appetite-boosting property of pro-melanin-concentrating hormone(131-165) (neuropeptide-glutamic acid-isoleucine) is associated with proteolytic resistance.
Melanin-concentrating hormone (MCH) is a cyclic neuropeptide, with a major role in stimulation of feeding behavior in mammals. MCH signals in the brain occur via two seven-transmembrane G protein-coupled receptors, namely MCH1 (SLC-1, MCH(1), MCH-R1, or MCH-1R) and MCH2 (SLT, MCH(2), MCH-R2, or MCH-2R). In this study, we demonstrate that the pro-MCH(131-165) peptide neuropeptide-glutamic acid-isoleucine (NEI)-MCH is more potent than MCH in stimulating feeding in the rat. Using rat MCH1-expressed human embryonic kidney 293 cells, we show that NEI-MCH exhibits 5-fold less affinity in a binding assay and 2-fold less potency in a cAMP assay than MCH. A similar 7- to 8-fold shift in potency was observed in a Ca(2+)(i) assay using rat MCH1 or human MCH2-transfected Chinese hamster ovary cell models. This demonstrates that NEI-MCH is not a better agonist than MCH at either of the MCH receptors. Then, we compared the proteolysis resistance of MCH and NEI-MCH to rat brain membrane homogenates and purified proteases. Kinetics of peptide degradation using brain extracts indicated a t(1/2) of 34.8 min for MCH and 78.5 min for NEI-MCH with a specific pattern of cleavage of MCH but not NEI-MCH by exo- and endo-proteases. Furthermore, MCH was found highly susceptible to degradation by aminopeptidase M and endopeptidase 24.11, whereas NEI-MCH was fully resistant to proteolysis by these enzymes. Therefore, our results strongly suggest that reduced susceptibility to proteases of NEI-MCH compared with MCH account for its enhanced activity in feeding behavior. NEI-MCH represents therefore the first MCH natural functional "superagonist" so far described.
Institut de Pharmacologie Moléculaire et Cellulaire-Centre National de la Recherche Scientifique, Unité Mixte de Recherche 6097, 660 route des Lucioles-Sophia-Antipolis, 06560 Valbonne, France.
Laurence
L
Maulon-Feraille
Odile
O
Della Zuana
Thomas
T
Suply
Carole
C
Rovere-Jovene
Valérie
V
Audinot
Nigel
N
Levens
Jean A
JA
Boutin
Jacques
J
Duhault
Jean-Louis
JL
Nahon
D000595:Amino Acid Sequence; D000818:Animals; D019167:Appetite Stimulants / Q000008:administration & dosage / Q000494:pharmacology*; D016466:CHO Cells; D020013:Calcium Signaling / Q000187:drug effects / Q000502:physiology; D002460:Cell Line; D002552:Cerebral Ventricles / Q000187:drug effects / Q000502:physiology*; D006224:Cricetinae; D000242:Cyclic AMP / Q000494:pharmacology; D005247:Feeding Behavior / Q000187:drug effects*; D006801:Humans; D007028:Hypothalamic Hormones / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*; D007276:Injections, Intraventricular; D007668:Kidney; D007700:Kinetics; D008297:Male; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000008:administration & dosage / Q000494:pharmacology*; D011498:Protein Precursors / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D014162:Transfection
D019167:Appetite Stimulants; D007028:Hypothalamic Hormones; D010446:Peptide Fragments; D011498:Protein Precursors; C059991:melanin-concentrating hormone precursors; D000242:Cyclic AMP