| 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. |
- Fällmar, Helena, 1980-, et al.
(författare)
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Neuropeptide Y/peptide YY receptor Y2 duplicate in zebrafish with unique introns displays distinct peptide binding properties
- 2011
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Ingår i: Comparative Biochemistry and Physiology - Part B. - : Elsevier BV. - 1096-4959 .- 1879-1107. ; 160:4, s. 166-173
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- The neuropeptide Y-family peptides and receptors are involved in a broad range of functions including appetite regulation. Both the peptide genes and the receptor genes are known to have duplicated in early vertebrate evolution. The ancestral jawed vertebrate had 7 NPY receptors but the number varies between 4 and 7 in extant vertebrates. Herein we describe the identification of an additional NPY receptor in two fish species, zebrafish and medaka. They cluster together with the Y2 receptors in phylogenetic analyses and seem to be orthologous to each other that is why we have named them Y2-2. Their genes differ from Y2 in having introns in the coding region. Binding studies with zebrafish Y2-2 receptors show that the three endogenous peptides NPY, PYYa and PYYb have similar affinities, 0.15-0.66nM. This is in contrast to the Y2 receptor where they differed considerably from one another. N-terminally truncated NPY binds poorly and the Y2 antagonist BIIE0246 binds well to Y2-2, results that are reversed in comparison to Y2. Zebrafish Y2-2 mRNA was detected by PCR in the intestine and the eye, but not in the brain. In conclusion, we have found a novel Y2-like NPY/PYY receptor that probably arose in early teleost fish evolution.
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| 3. |
- Fällmar, Helena, 1980-
(författare)
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Studies of the Neuropeptide Y Receptor Y2 in Human and Zebrafish
- 2011
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The G-protein coupled receptors (GPCRs) comprise the largest family of receptors in humans and other vertebrates. They are embedded in the cell membrane and are activated by many different signaling molecules. Activation modulates cellular signal transduction pathways and influences many physiological processes. Therefore the GPCRs are important as targets for numerous drugs. The receptors for NPY (neuropeptide Y) belong to GPCRs of Class A (rhodopsin-like). NPY and its related peptides PYY and PP are involved in the regulation of appetite, blood pressure and many other processes. They share a common structure and interact with the receptors Y1, Y2, Y4 and Y5 in mammals, and, in addition, Y7 and Y8 in amphibians and bony fishes. This thesis is focused on the human Y2 receptor, known to reduce appetite, by investigating the importance of thirteen amino acid residues for ligand binding. Mutagenesis followed by functional expression and receptor binding was conducted. During the course of this work several new GPCR crystal structures have been resolved, thereby improving the receptor modeling in papers I-III. The major finding is that even though the Y1 and Y2 receptors have evolved from a common ancestor, their points of ligand interaction differ and have thus changed during evolution. In general, the positions investigated resulted in milder changes in the ligands’ affinities for Y2 compared to Y1. These findings were incorporated in the design of new Y1 and Y2 receptor models, leading to improved understanding of how such divergent receptors, sharing only 30 percent sequence identity, can still interact with the same ligands. Notably, several of the mutations introduced in Y2 resulted in increased affinity. A novel NPY receptor gene named Y2-2 was identified in the genomes of zebrafish and medaka. This brings the number of zebrafish NPY receptors to seven. The binding characteristics of zebrafish Y2-2 differed from zebrafish Y2 mainly in the interaction with NPY13-36 and the antagonist BIIE0246. In conclusion, these results increase our understanding of ligand interactions with GPCRs and will be useful for refinement of ligand-receptor models for future development of receptor subtype-selective drugs.
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| 4. |
- Hansson, J., et al.
(författare)
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Monitoring of kindreds with hereditary predisposition for cutaneous melanoma and dysplastic nevus syndrome: results of a Swedish preventive program
- 2007
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Ingår i: J Clin Oncol. ; 25:19, s. 2819-2824
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Tidskriftsartikel (refereegranskat)abstract
- PURPOSE: To evaluate a program initiated in 1987 by the Swedish Melanoma Study Group aiming to provide preventive surveillance to kindreds with hereditary cutaneous melanoma and dysplastic nevus syndrome. PATIENTS AND METHODS: Overall, 2,080 individuals belonging to 280 melanoma families were followed for 14 years between 1987 and 2001 at 12 participating centers. Data were registered in a central database. RESULTS: Among 1,912 skin lesions excised during follow-up, 41 melanomas were removed in 32 individuals. Of these, 15 (37%) were in situ melanomas and 26 (63%) invasive melanomas. The median tumor thickness of invasive melanomas was 0.5 mm. Ulceration was absent in 24 of 26 invasive melanomas (92%) and 12 (46%) lacked vertical growth phase. Compared with melanomas in the general Swedish population, the melanomas identified in these kindreds during follow-up had better prognostic characteristics. All melanomas except one were diagnosed in families with two or more first-degree relatives with melanoma. Diagnosis of melanoma occurred in three of eight kindreds with germline CDKN2A mutations, supporting that families with such mutations are at increased risk for melanoma development. Of the 32 individuals who developed melanoma during follow-up, 21 (66%) had had at least one previously diagnosed melanoma. CONCLUSION: This study shows that a coordinated program aimed at detecting and offering skin surveillance in kindreds with hereditary cutaneous melanoma results in a low incidence of melanomas during the follow-up period and that the tumors that do arise have favorable prognostic characteristics.
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| 5. |
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| 6. |
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| 7. |
- Lundell, Ingrid, et al.
(författare)
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Internalization studies of chimeric neuropeptide Y receptors Y1 and Y2 suggest complex interactions between cytoplasmic domains
- 2011
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Ingår i: Regulatory Peptides. - : Elsevier BV. - 0167-0115 .- 1873-1686. ; 168:1-3, s. 50-58
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Tidskriftsartikel (refereegranskat)abstract
- Agonist stimulation readily internalizes neuropeptide Y receptor Y1 while there are contradictory results for the Y2 receptor. In order to explore putative functional differences between the Y1 and Y2 receptors we generated reciprocal chimeras by swapping the third intracellular loop, the carboxy terminus or both between human Y1 and Y2. Internalization was studied in a quantitative radioligand binding assay with removal of surface-bound ligand in an acidic-wash procedure. The internalization assay revealed a lower degree of internalization as well as slower kinetics for the Y2 receptor. Generally, reciprocal exchange of receptor segments did not convey properties of the donor receptor but tended to enhance internalization. Surprisingly, insertion of the Y2 carboxy terminus into Y1 gave almost complete internalization (92%), rather than reduced internalization, while the insertion of both segments resulted in internalization equal to the native Y1 receptor. These findings were confirmed by fluorescence microscopy of immuno-stained receptors tagged with a C-terminal FLAG epitope. However, after exposure to high agonist concentrations (100 nM) Y2 was internalized. Studies of Y2 and the closely related Y7 receptor confirmed low internalization for Y2 from chicken and teleost fishes as well as Y7 from two teleosts. The conservation across species of low internalization at physiological concentrations suggests that this is an ancient feature and of vital importance for Y2 function. We propose that amino acid motifs in the third intracellular loop as well as the C terminus of both Y1 and Y2 are able to drive agonist-promoted internalization and that there may be constraining motifs in the Y2 receptor.
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| 8. |
- Sundström, Görel, et al.
(författare)
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Characterization of the neuropeptide Y system in the frog Silurana tropicalis (Pipidae) : three peptides and six receptor subtypes
- 2012
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Ingår i: General and Comparative Endocrinology. - : Elsevier BV. - 0016-6480 .- 1095-6840. ; 177:3, s. 322-331
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Tidskriftsartikel (refereegranskat)abstract
- Neuropeptide Y and its related peptides PYY and PP (pancreatic polypeptide) are involved in feeding behavior, regulation of the pituitary and the gastrointestinal tract, and numerous other functions. The peptides act on a family of G-protein coupled receptors with 4-7 members in jawed vertebrates. We describe here the NPY system of the Western clawed frog Silurana (Xenopus) tropicalis. Three peptides, NPY, PYY and PP, were identified together with six receptors, namely subtypes Y1, Y2, Y4, Y5, Y7 and Y8. Thus, this frog has all but one of the ancestral seven gnathostome NPY-family receptors, in contrast to mammals which have lost 2-3 of the receptors. Expression levels of mRNA for the peptide and receptor genes were analyzed in a panel of 19 frog tissues using reverse transcriptase quantitative PCR. The peptide mRNAs had broad distribution with highest expression in skin, blood and small intestine. NPY mRNA was present in the three brain regions investigated, but PYY and PP mRNAs were not detectable in any of these. All receptor mRNAs had similar expression profiles with high expression in skin, blood, muscle and heart. Three of the receptors, Y5, Y7 and Y8, could be functionally expressed in HEK-293 cells and characterized with binding studies using the three frog peptides. PYY had the highest affinity for all three receptors (K(i) 0.042-0.34 nM). Also NPY and PP bound to the Y8 receptor with high affinity (0.14 and 0.50 nM). The low affinity of NPY for the Y5 receptor (100-fold lower than PYY) differs from mammals and chicken. This may suggest a less important role of NPY on Y5 in appetite stimulation in the frog compared with amniotes. In conclusion, our characterization of the NPY system in S. tropicalis with its six receptors demonstrates not only greater complexity than in mammals but also some interesting differences in ligand-receptor preferences.
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| 9. |
- Wallin Lundell, Inger, et al.
(författare)
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Posttraumatic stress among women after induced abortion : a Swedish multi-centre cohort study
- 2013
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Ingår i: BMC Women's Health. - : BioMed Central. - 1472-6874. ; 13, s. Article Number: 52-
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Tidskriftsartikel (refereegranskat)abstract
- Background: Induced abortion is a common medical intervention. Whether psychological sequelae might follow induced abortion has long been a subject of concern among researchers and little is known about the relationship between posttraumatic stress disorder (PTSD) and induced abortion. Thus, the aim of the study was to assess the prevalence of PTSD and posttraumatic stress symptoms (PTSS) before and at three and six months after induced abortion, and to describe the characteristics of the women who developed PTSD or PTSS after the abortion. Methods: This multi-centre cohort study included six departments of Obstetrics and Gynaecology in Sweden. The study included 1457 women who requested an induced abortion, among whom 742 women responded at the three-month follow-up and 641 women at the six-month follow-up. The Screen Questionnaire-Posttraumatic Stress Disorder (SQ-PTSD) was used for research diagnoses of PTSD and PTSS, and anxiety and depressive symptoms were evaluated by the Hospital Anxiety and Depression Scale (HADS). Measurements were made at the first visit and at three and six months after the abortion. The 95% confidence intervals for the prevalence of lifetime or ongoing PTSD and PTSS were calculated using the normal approximation. The chi-square test and the Student's t-test were used to compare data between groups. Results: The prevalence of ongoing PTSD and PTSS before the abortion was 4.3% and 23.5%, respectively, concomitant with high levels of anxiety and depression. At three months the corresponding rates were 2.0% and 4.6%, at six months 1.9% and 6.1%, respectively. Dropouts had higher rates of PTSD and PTSS. Fifty-one women developed PTSD or PTSS during the observation period. They were young, less well educated, needed counselling, and had high levels of anxiety and depressive symptoms. During the observation period 57 women had trauma experiences, among whom 11 developed PTSD or PTSS and reported a traumatic experience in relation to the abortion. Conclusion: Few women developed PTSD or PTSS after the abortion. The majority did so because of trauma experiences unrelated to the induced abortion. Concomitant symptoms of depression and anxiety call for clinical alertness and support.
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| 10. |
- Wallin Lundell, Inger, et al.
(författare)
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The prevalence of posttraumatic stress among women requesting induced abortion
- 2013
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Ingår i: European journal of contraception & reproductive health care. - : Informa Healthcare. - 1362-5187 .- 1473-0782. ; 18:6, s. 480-488
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Tidskriftsartikel (refereegranskat)abstract
- Objectives To describe the prevalence and pattern of traumatic experiences, to assess the prevalence of posttraumatic stress disorder (PTSD) and posttraumatic stress symptoms (PTSS), to identify risk factors for PTSD and PTSS, and to analyse the association of PTSD and PTSS with concomitant anxiety and depressive symptoms in women requesting induced abortion. less thanbrgreater than less thanbrgreater thanMethods A Swedish multi-centre study of women requesting an induced abortion. The Screen Questionnaire - Posttraumatic Stress Disorder was used for research diagnoses of PTSD and PTSS. Anxiety and depressive symptoms were evaluated by the Hospital Anxiety and Depression Scale (HADS). less thanbrgreater than less thanbrgreater thanResults Of the 1514 respondents, almost half reported traumatic experiences. Lifetime-and point prevalence of PTSD were 7% (95% confi dence interval [CI]: 5.8-8.5) and 4% (95% CI: 3.1-5.2), respectively. The prevalence of PTSS was 23% (95% CI: 21.1-25.4). Women who reported symptoms of anxiety or depression when requesting abortion were more likely to have ongoing PTSD or PTSS. Also single-living women and smokers displayed higher rates of ongoing PTSD. less thanbrgreater than less thanbrgreater thanConclusions Although PTSD is rare among women who request an induced abortion, a relatively high proportion suffers from PTSS. Abortion seeking women with trauma experiences and existing or preexisting mental disorders need more consideration and alertness when counselled for termination.
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