| 1. |
- Fällmar, Helena, 1980-, et al.
(författare)
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Identification of positions in the human neuropeptide Y/peptide YY receptor Y2 that contribute to pharmacological differences between receptor subtypes
- 2011
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Ingår i: Neuropeptides. - : Elsevier BV. - 0143-4179 .- 1532-2785. ; 45:4, s. 293-300
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Tidskriftsartikel (refereegranskat)abstract
- The members of the neuropeptide Y (NPY) family are key players in food-intake regulation. In humans this family consists of NPY, peptide YY (PYY) and pancreatic polypeptide (PP) which interact with distinct preference for the four receptors showing very low sequence identity, i.e. Y1, Y2, Y4 and Y5. The binding of similar peptides to these divergent receptors makes them highly interesting for mutagenesis studies. We present here a site-directed mutagenesis study of four amino acid positions in the human Y2 receptor. T(3.40) was selected based on sequence alignments both between subtypes and between species and G(2.68), L(4.60) and Q(6.55) also on previous binding studies of the corresponding positions in the Y1 receptor. The mutated receptors were characterized pharmacologically with the peptide agonists NPY, PYY, PYY(3-36), NPY(13-36) and the non-peptide antagonist BIIE0246. Interestingly, the affinity of NPY and PYY(3-36) increased for the mutants T(3.40)I and Q(6.55)A. Increased affinity was also observed for PYY to Q(6.55)A. PYY(3-36) displayed decreased affinity for G(2.68)N and L(4.60)A whereas binding of NPY(13-36) was unaffected by all mutations. The antagonist BIIE0246 showed decreased affinity for T(3.40)I, L(4.60)A and Q(6.55)A. Although all positions investigated were found important for interaction with at least one of the tested ligands the corresponding positions in hY1 seem to be of greater importance for ligand binding. Furthermore these data indicate that binding of the agonists and the antagonist differs in their points of interaction. The increase in the binding affinity observed may reflect an indirect effect caused by a conformational change of the receptor. These findings will help to improve the structural models of the human NPY receptors.
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| 2. |
- Åkerberg, Helena, et al.
(författare)
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Mutagenesis of human neuropeptide Y/peptide YY receptor Y2 reveals additional differences to Y1 in interactions with highly conserved ligand positions
- 2010
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Ingår i: Regulatory Peptides. - : Elsevier BV. - 0167-0115 .- 1873-1686. ; 163:1-3, s. 120-129
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Tidskriftsartikel (refereegranskat)abstract
- Neuropeptide Y (NPY) and peptide YY (PYY) share similar to 70% of their 36 amino acids and bind to the same three human receptor subtypes, Y1, Y2 and Y5, even though these receptors only share similar to 30% sequence identity Based on our previous investigation of human Y1 we describe here a mutagenesis study of three corresponding positions in human Y2, i e Tyr(2 64), Val(6 58) and Tyr(7 31) Pharmacological characterization was performed with the four peptide agonists PYY, NPY, PYY(3-36) and NPY(13-36) as well as the non-peptide antagonist BIIE0246 Results from mutants where Tyr(2 64) has been substituted by Ala suggest that Tyr(2 64) is involved in the interaction with all investigated ligands whereas position Tyr(7 31) seems to be more important for interaction with the truncated peptide PYY(3-36) than with intact NPY Surprisingly, substitution of Tyr(7 31) with His, the corresponding residue in Y1, resulted in total loss of binding of iodinated porcine PYY The third position. Val(6 58), did not influence binding of any of the ligands. These findings differ from those obtained for Y1 where Ala substitution resulted in lost or changed binding for each of the three positions. Although Tyr(2 64) and Tyr(7 31) in Y2 are involved in ligand binding, their interactions with the peptide ligands seem to be different from the corresponding positions in Y1 This suggests that the receptor-ligand interactions have changed during evolution after Y1 and Y2 arose from a common ancestral receptor.
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| 3. |
- Gruber, Kenneth A, et al.
(författare)
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Neuropeptide Y and gamma-melanocyte stimulating hormone (gamma-MSH) share a common pressor mechanism of action
- 2009
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Ingår i: Endocrine. - : Springer Science and Business Media LLC. - 1355-008X .- 1559-0100. ; 35:3, s. 312-324
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Tidskriftsartikel (refereegranskat)abstract
- Central circuits known to regulate food intake and energy expenditure also affect central cardiovascular regulation. For example, both the melanocortin and neuropeptide Y (NPY) peptide families, known to regulate food intake, also produce central hypertensive effects. Members of both families share a similar C-terminal amino acid residue sequence, RF(Y) amide, a sequence distinct from that required for melanocortin receptor binding. A recently delineated family of RFamide receptors recognizes both of these C-terminal motifs. We now present evidence that an antagonist with Y1 and RFamide receptor activity, BIBO3304, will attenuate the central cardiovascular effects of both gamma-melanocyte stimulating hormone (gamma-MSH) and NPY. The use of synthetic melanocortin and NPY peptide analogs excluded an interaction with melanocortin or Y family receptors. We suggest that the anatomical convergence of NPY and melanocortin neurons on cardiovascular control centers may have pathophysiological implications through a common or similar RFamide receptor(s), much as they converge on other nuclei to coordinately control energy homeostasis.
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| 4. |
- Sjödin, Paula, et al.
(författare)
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Re-evaluation of receptor–ligand interactions of the human neuropeptide Y receptor Y1 : a site-directed mutagenesis study
- 2006
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Ingår i: Biochemical Journal. - 0264-6021 .- 1470-8728. ; 1:393, s. 161-169
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Tidskriftsartikel (refereegranskat)abstract
- Interactions of the human NPY (neuropeptide Y) receptor Y1 with the two endogenous agonists NPY and peptide YY and two non-peptide antagonists were investigated using site-directed mutagenesis at 17 positions. The present study was triggered by contradictions among previously published reports and conclusions that seemed inconsistent with sequence comparisons across species and receptor subtypes. Our results show that Asp287, at the border between TM (transmembrane) region 6 and EL3 (extracellular loop 3) influences peptide binding, while two aspartic residues in EL2 do not, in agreement with some previous studies but in disagreement with others. A hydrophobic pocket of the Y1 receptor consisting of Tyr100 (TM2), Phe286 (TM6) and His298 (EL3) has been proposed to interact with the amidated C-terminus of NPY, a theory that is unsupported by sequence comparisons between Y1, Y2 and Y5. Nevertheless, our results confirm that these amino acid residues are critical for peptide binding, but probably interact with NPY differently than proposed previously. Studies with the Y1-selective antagonist SR120819A identified a new site of interaction at Asn116 in TM3. Position Phe173 in TM4 is also important for binding of this antagonist. In contrast with previous reports, we found that Phe173 is not crucial for the binding of BIBP3226, another selective Y1 receptor antagonist. Also, we found that position Thr212 (TM5) is important for binding of both antagonists. Our mutagenesis results and our three-dimensional model of the receptor based on the high-resolution structure of bovine rhodopsin suggest new interactions for agonist as well as antagonist binding to the Y1 receptor.
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| 5. |
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| 6. |
- Åkerberg, Helena, 1978-
(författare)
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Functional Studies of the Neuropeptide Y System : Receptor-Ligand Interaction and Regulation of Food Intake
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The members of the mammalian neuropeptide Y family, i.e. the peptides neuropeptide Y (NPY), peptide YY (PYY) and pancreatic polypeptide (PP), are all involved in regulation of food intake. In human and most other mammals they act via receptors Y1, Y2, Y4 and Y5. NPY is released in the hypothalamus and is one of the strongest appetite-stimulating neurotransmitters whereas PP and PYY are secreted from gut endocrine cells after meals and function as appetite-reducing hormones. This thesis describes studies of the NPY system at both the molecular and the physiological level. The first part describes two investigations of receptor-ligand interactions with the human Y1 and Y2 receptors. The results clarify the importance of several amino-acid residues of the human Y1 receptor. Three amino acids previously suggested by others to form a binding pocket for the carboxy-terminus of the peptide were confirmed to be crucial for interaction with peptide ligands. However, they were found to be too distantly located from each other to be able to form a binding pocket. Further investigation of the three corresponding positions in the human Y2 receptor showed that only one of the positions was important for interaction with full-length peptides. The results indicate overlapping but, surprisingly, non-identical binding of the different peptides to human Y1 and Y2 receptors, despite the fact that the two receptors share a common ancestor. The second part of the thesis describes an investigation of the effect of PP on food intake in six beagle dogs and a test for personality characteristics in dogs (TFPC). Treatment with physiological doses of PP decreased both the appetitive and the consummatory drive but had no effect on the amount food consumed. The TFPC protocol was used to map individual behavioral differences in a population of sixteen beagle dogs. The test, which included several situations that may appear in an experimental study, revealed considerable inter-individual differences in behavioral responses despite the fact that the dogs were born and housed in the same animal facility in constant controlled conditions. These results demonstrate that PP can influence food intake in distantly related mammals and emphasize the importance of considering differences in personality in experimental animals.
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| 7. |
- Åkerberg, Helena, et al.
(författare)
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Peripheral administration of pancreatic polypeptide inhibits components of food- intake behavior in dogs
- 2010
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Ingår i: Peptides. - : Elsevier BV. - 0196-9781 .- 1873-5169. ; 31:6, s. 1055-1061
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Tidskriftsartikel (refereegranskat)abstract
- Pancreatic polypeptide (PP) belongs to the neuropeptide Y (NPY) family of peptides and is released from pancreatic F cells postprandially. PP functions as a peptide hormone and has been associated with decreased food intake in humans and rodents. Our study describes the effects of PP on feeding behavior in dogs, whose mammalian order (Carnivora) is more distantly related to primates and rodents than these are to each other. Furthermore, obesity is becoming more prevalent in dogs which makes knowledge about their appetite regulation highly relevant. Repeated peripheral administration of physiological doses of PP (three injections of 30 pmol/kg each that were administered within 30 min) to six male beagle dogs prolonged the median time spent eating three servings of food by 19% but resulted in no reduction of food intake. In addition, PP decreased the duration of food-seeking behavior after the first serving by 71%. Thus, a physiological dose of PP seems to decrease both the appetitive and the consummatory drive in dogs.
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| 8. |
- Åkerberg, Helena, et al.
(författare)
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Test for personality characteristics in dogs used in research
- 2012
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Ingår i: Journal of Veterinary Behavior. - : Elsevier BV. - 1558-7878 .- 1878-7517. ; 7:6, s. 327-338
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Tidskriftsartikel (refereegranskat)abstract
- The great variation in morphological phenotypes displayed by dogs offers not only excellent opportunities for genetic analyses but also a challenge regarding between-breed and even within-breed variation. Also, behavioral responses may vary between individuals, and are to be taken into account in experimental situations. To our knowledge, no standardized test for scoring personality characteristics (TFPC) in dogs maintained for research under controlled conditions has yet been developed. The present article describes a protocol consisting of 9 test situations that are likely to arise in experimental contexts. The intent was to establish an easy-to-use standardized test protocol. Sixteen beagles were used, all housed in constant and controlled conditions. The results revealed considerable individual differences in response to certain stimuli. The largest within-group variation was found when being caged; the responses varied from passivity to escape attempts (score range: 2-5 in a 5-step scale). Substantial variation was also seen in locomotion and food consumption after exposure to stress (score range: 1-5 in a 5-step scale). In a new environment, the females showed more frequent changes in attention (focusing) compared with males (P < 0.01). There was an age-related reaction to sudden sounds (Spearman r sp = -0.52, P < 0.05). We also describe application of the TFPC to a study of food intake in response to pancreatic polypeptide performed with 6 of the male dogs. A within-group rank-order procedure was used, and interesting correlations between personality characteristics and food intake behavior were identified. We discuss how the TFPC may contribute to improvement of experimental studies in dogs.
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