An aromatic region to induce a switch between agonism and inverse agonism at the ghrelin receptor

TY - JOUR

T1 - An aromatic region to induce a switch between agonism and inverse agonism at the ghrelin receptor

AU - Els, Sylvia

AU - Schild, Enrico

AU - Petersen, Pia Steen

AU - Kilian, Tom-Marten

AU - Mokrosinski, Jacek

AU - Frimurer, Thomas M

AU - Chollet, Constance

AU - Schwartz, Thue W

AU - Holst, Birgitte

AU - Beck-Sickinger, Annette G

PY - 2012/9/13

Y1 - 2012/9/13

N2 - The ghrelin receptor displays a high constitutive activity suggested to be involved in the regulation of appetite and food intake. Here, we have created peptides with small changes in the core binding motif -wFw- of the hexapeptide KwFwLL-NH(2) that can swap the peptide behavior from inverse agonism to agonism, indicating the importance of this sequence. Introduction of β-(3-benzothienyl)-d-alanine (d-Bth), 3,3-diphenyl-d-alanine (d-Dip) and 1-naphthyl-d-alanine (d-1-Nal) at position 2 resulted in highly potent and efficient inverse agonists, whereas the substitution of d-tryptophane at position 4 with 1-naphthyl-d-alanine (d-1-Nal) and 2-naphthyl-d-alanine (d-2-Nal) induces agonism in functional assays. Competitive binding studies showed a high affinity of the inverse agonist K-(d-1-Nal)-FwLL-NH(2) at the ghrelin receptor. Moreover, mutagenesis studies of the receptor revealed key positions for the switch between inverse agonist and agonist response. Hence, only minor changes in the peptide sequence can decide between agonism and inverse agonism and have a major impact on the biological activity.

AB - The ghrelin receptor displays a high constitutive activity suggested to be involved in the regulation of appetite and food intake. Here, we have created peptides with small changes in the core binding motif -wFw- of the hexapeptide KwFwLL-NH(2) that can swap the peptide behavior from inverse agonism to agonism, indicating the importance of this sequence. Introduction of β-(3-benzothienyl)-d-alanine (d-Bth), 3,3-diphenyl-d-alanine (d-Dip) and 1-naphthyl-d-alanine (d-1-Nal) at position 2 resulted in highly potent and efficient inverse agonists, whereas the substitution of d-tryptophane at position 4 with 1-naphthyl-d-alanine (d-1-Nal) and 2-naphthyl-d-alanine (d-2-Nal) induces agonism in functional assays. Competitive binding studies showed a high affinity of the inverse agonist K-(d-1-Nal)-FwLL-NH(2) at the ghrelin receptor. Moreover, mutagenesis studies of the receptor revealed key positions for the switch between inverse agonist and agonist response. Hence, only minor changes in the peptide sequence can decide between agonism and inverse agonism and have a major impact on the biological activity.

KW - Animals

KW - COS Cells

KW - Cercopithecus aethiops

KW - Feeding Behavior

KW - Humans

KW - Models, Molecular

KW - Mutagenesis

KW - Oligopeptides

KW - Rats

KW - Receptors, Ghrelin

U2 - 10.1021/jm300414b

DO - 10.1021/jm300414b

M3 - Journal article

C2 - 22920150

SN - 0022-2623

VL - 55

SP - 7437

EP - 7449

JO - Journal of Medicinal Chemistry

JF - Journal of Medicinal Chemistry

IS - 17

ER -