Cloning of neuropeptide Y, peptide YY, and peptide Y from sea bass (Dicentrarchus labrax), a marine teleost.
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Amino Acid Sequence↗
Biomedical subjects
D Larhammar
Publications and source records attributed to D Larhammar.
FISH mapping of the porcine NPY5 gene to chromosome 8p11.
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Animals↗
Vertebrate genome evolution and the zebrafish gene map.
In chordate phylogeny, changes in the nervous system, jaws, and appendages transformed meek filter feeders into fearsome predators. Gene duplication is thought to promote such innovation. Vertebrate ancestors probably had single copies of genes now found in multiple copies in vertebrates and gene maps suggest that this occurred by polyploidization. It has been suggested that one genome duplication event occurred before, and one after the divergence of ray-finned and lobe-finned fishes. Holland et al., however, have argued that because various vertebrates have several HOX clusters, two rounds of duplication occurred before the origin of jawed fishes. Such gene-number data, however, do not distinguish between tandem duplications and polyploidization events, nor whether independent duplications occurred in different lineages. To investigate these matters, we mapped 144 zebrafish genes and compared the resulting map with mammalian maps. Comparison revealed large conserved chromosome segments. Because duplicated chromosome segments in zebrafish often correspond with specific chromosome segments in mammals, it is likely that two polyploidization events occurred prior to the divergence of fish and mammal lineages. This zebrafish gene map will facilitate molecular identification of mutated zebrafish genes, which can suggest functions for human genes known only by sequence.
Animals↗
Co-localized neuropeptide Y and GABA have complementary presynaptic effects on sensory synaptic transmission.
We have examined the morphological relationship of neuropeptide Y (NPY) and GABAergic neurons in the lamprey spinal cord, and the physiological effects of NPY and GABA(B) receptor agonists on afferent synaptic transmission. NPY-containing fibres and cell bodies were identified in the dorsal root entry zone. NPY immunoreactive (-ir) fibres made close appositions with primary afferent axons. Co-localization of NPY and GABA-ir was found in the dorsal horn and dorsal column. Fifty-two per cent of NPY-ir profiles showed immunoreactivity to GABA at the ultrastructural level. Electron microscopic analysis showed that NPY-immunoreactivity was present throughout the axoplasm, including over dense core vesicles, whereas GABA-immunoreactivity was mainly found over small synaptic vesicles. Synthetic lamprey NPY, and the related peptide, peptide YY, reduced the amplitude of monosynaptic afferent EPSPs in spinobulbar neurons. NPY had no significant effect on the postsynaptic input resistance or membrane potential, the electrical component of the synaptic potential, or the response to glutamate, but it could reduce the duration of presynaptic action potentials, suggesting that it was acting presynaptically. NPY also reduced the excitability of the spinobulbar neurons, suggesting at least one postsynaptic effect. Because NPY and GABA colocalize, we compared the effects of NPY and the GABA(B) agonist baclofen. Both presynaptically reduced EPSP amplitudes, baclofen having a larger effect and a faster onset and recovery than NPY. The GABA(B) antagonist phaclofen reduced the effect of baclofen, but not that of NPY. We conclude that NPY and GABA are colocalized in terminals in the dorsal spinal cord of the lamprey, and that they have complementary actions in modulating sensory inputs.
Animals↗
XVI. International Union of Pharmacology recommendations for the nomenclature of neuropeptide Y, peptide YY, and pancreatic polypeptide receptors.
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Amino Acid Sequence↗
Multiplicity of neuropeptide Y receptors: cloning of a third distinct subtype in the zebrafish.
Five different receptor subtypes for neuropeptide Y (NPY) have recently been cloned in mammals. We have discovered three distinct subtypes by PCR in the zebrafish, Danio rerio, and describe here one of these called zYc. The protein sequence identity is 46-51% to mammalian subtypes Y1, Y4 and Y6 and to zebrafish Ya, i.e., the same degree of identity as these subtypes display to one another. The identity to zYb is higher, 75%, indicating that zYb and zYc share a more recent ancestor. The zYc receptor binds NPY and PYY (peptide YY) from mammals as well as zebrafish with high affinities and has a Kd of 16 pM for 125I-pPYY. The pharmacological profile is similar to, but distinct-from, mammalian Y1. zYc inhibits cAMP synthesis. This work suggests that NPY has more receptor subtypes than any other peptide that binds to G protein-coupled receptors. Work is in progress to see if the zebrafish receptors are present in mammals.
Amino Acid Sequence↗
Complex gene organization of synaptic protein SNAP-25 in Drosophila melanogaster.
The evolutionarily conserved protein SNAP-25 (synaptosome-associated protein 25 kDa (kilodaltons)) is a component of the protein complex involved in the docking and/or fusion of synaptic vesicles in nerve terminals. We report here that the SNAP-25 gene (Snap) in the fruit fly Drosophila melanogaster has a complex organization with eight exons spanning more than 120 kb (kilobases). The exon boundaries coincide with those of the chicken SNAP-25 gene (Bark, 1993). Only a single exon 5 has been found in Drosophila, whereas human, rat, chicken, zebrafish and goldfish have two alternatively spliced versions of this exon. In situ hybridization and immunocytochemistry to whole mount embryos show that SNAP-25 mRNA and protein are detected in stage 14 and later developmental stages, and are mainly localized to the ventral nerve cord. Thus, Snap has an evolutionarily conserved and complex gene organization, and its onset of expression in Drosophila melanogaster correlates with a time in neuronal development when synapses begin to be formed and when other synapse-specific genes are switched on.
Amino Acid Sequence↗
Embryonic expression of the mRNA for the rat homologue of the fusin/CXCR-4 HIV-1 co-receptor.
We have previously cloned a human receptor recently shown to be a cofactor for entry of T-tropic HIV-1 strains into CD4+ cells, now named fusin. Stromal derived factor-1 (SDF-1) is an endogenous ligand for fusin, also called CXCR-4. Here we show the distribution of fusin/CXCR-4 mRNA during ontogeny in the rat. The onset of mRNA expression is around embryonic day 9 and the mRNA expression is high in the thymus as well as proliferative areas of the brain during development. Our results suggest: (1) that fusin/CXCR-4 might have a dual role in both brain development and the immune system; (2) that SDF-1 has a role in brain development or that additional physiological ligands exist for this receptor; (3) co-expression of CD4 and fusin/CXCR-4 may make fetuses susceptible to HIV infection during development.
Animals↗
[125I]Leu31, Pro34-PYY is a high affinity radioligand for rat PP1/Y4 and Y1 receptors: evidence for heterogeneity in pancreatic polypeptide receptors.
Cloned receptors for the PP-fold peptides are subdivided into Y1, Y2, PP1/Y4, Y5 and Y6. NPY and PYY have similar affinity for Y1, Y2, Y5 and Y6 receptors while PP has highest affinity for PP1. Pro34-substituted analogs of NPY and PYY have selectivity for Y1 and Y1-like receptors over Y2 receptors. In the present study, we found the putative Y1-selective radioligand, [125I]Leu31, Pro34-PYY, also binds with high affinity to the rat PP1 receptor in cell lines expressing the receptor. However, in rat brain sections, [125I]Leu31, Pro34-PYY does not appear to bind to the interpeduncular nucleus, a brain region containing a high density of [125I]-bPP binding sites. Therefore, it appears there is additional heterogeneity in receptors recognizing PP.
Animals↗
Differential distribution of glutamic acid decarboxylase-65 and glutamic acid decarboxylase-67 messenger RNAs in the entopeduncular nucleus of the rat.
The entopeduncular nucleus is one of the major output nuclei of the basal ganglia, with topographically organized projections to both motor and limbic structures. Neurons of the entopeduncular nucleus use GABA as the principal transmitter, and glutamic acid decarboxylase (the GABA synthetic enzyme) is widely distributed throughout the region. Previous studies have shown that glutamate decarboxylase exists in two forms (glutamic acid decarboxylase-65 and glutamic acid decarboxylase-67), and that the messenger RNAs for these different enzymes are widely distributed in rat brain. The purpose of the present experiment was to describe the distribution of glutamic acid decarboxylase-65 and glutamic decarboxylase-67 messenger RNAs throughout the entopeduncular nucleus using recently developed oligodeoxynucleotide probes and in situ hybridization histochemical methods. In agreement with previous studies, northern analysis of rat brain poly(A)+ messenger RNA preparations showed that the glutamic acid decarboxylase-65 and glutamic acid decarboxylase-67 probes used in the present study hybridized to messenger RNAs of approximately 5.7 and 3.7 kb, respectively. Film autoradiographic analysis revealed large region-dependent, isoform-specific differences in the levels of expression of the two messenger RNAs, with glutamic acid decarboxylase-65 messenger RNA predominating in rostral and medial regions of the entopeduncular nucleus and glutamic acid decarboxylase-67 messenger RNA most abundant in the caudal region. Cellular analysis showed that these region-dependent differences in labelling were due to differences in the relative amounts of glutamic acid decarboxylase-65 and glutamic acid decarboxylase-67 messenger RNAs expressed per cell rather than the number of cells expressing each form of glutamic acid decarboxylase messenger RNA. The differences in the distribution of glutamic acid decarboxylase-65 and glutamic acid decarboxylase-67 messenger RNAs are closely related to the organization of limbic and motor circuits of the entopeduncular nucleus, suggesting that GABAergic transmission through the limbic pathway is regulated predominantly by glutamic acid decarboxylase-65, whereas glutamic acid decarboxylase-67 is of principal importance in the motor pathway. These data provide additional evidence that the neurons of the limbic and motor subregions of the entopeduncular nucleus are neurochemically distinct.
Animals↗
Cloning and characterization of a novel neuropeptide Y receptor subtype in the zebrafish.
Neuropeptide Y (NPY), peptide YY (PYY), and pancreatic polypeptide (PP) form a family of structurally related peptides. As we have previously isolated clones for NPY and PYY from the zebrafish (Danio rerio), we wished to clone the receptors for these peptides to allow correlation of ligand and receptor distribution. We describe here the cloning and functional expression of a receptor with equally high identity to the NPY-Y1 receptor as to the recently cloned Y4/PP1 and Y6 receptors with an overall amino acid sequence identity of approximately 50%. Furthermore, the zebrafish receptor gene lacks the intron present in the coding region in vertebrate Y1 genes. These features strongly suggest that the zebrafish receptor represents a separate subtype. Hence, we have named it zYb for zebrafish Y-receptor b. (We have also discovered a unique receptor called zYa.) The zYb receptor has a binding profile that is reminiscent of Y1 with affinities for NPY and PYY in the low picomolar range, whereas affinities for Y2-selective ligands are considerably lower. It couples to adenylyl cyclase by inhibiting cAMP synthesis. Receptor mRNA was detected by reverse transcription polymerase chain reaction (RT-PCR) in brain, eye, and intestine. The binding profile and amino acid identity show that the zebrafish zYb receptor is related to Y1 but represents a distinct subtype that is likely to be present also in mammals.
Amino Acid Sequence↗
The neuropeptide Y Y1 receptor selective radioligand, [125I][Leu31,Pro34]peptide YY, is also a high affinity radioligand for human pancreatic polypeptide 1 receptors.
A number of receptors for the pancreatic polypeptide-fold peptides are proposed based on findings from pharmacology and molecular biology studies. Neuropeptide Y and peptide YY have similar affinity for neuropeptide Y Y1 and neuropeptide Y Y2 while pancreatic polypeptide has highest affinity for pancreatic polypeptide 1. Pro34-substituted analogs of neuropeptide Y and peptide YY have selectivity for neuropeptide Y Y1 over neuropeptide Y Y2 receptors. In the present study, we found that one such 'neuropeptide Y Y1-selective' radioligand, [125I][Leu31,Pro34]peptide YY, also binds with high affinity to the pancreatic polypeptide 1 receptor. Therefore, caution needs to be exercised when using Pro34-analogs to define the neuropeptide Y Y1 receptor in vivo and using tissue preparations.
Cell Line↗
Structural diversity of receptors for neuropeptide Y, peptide YY and pancreatic polypeptide.
The NPY (neuropeptide Y) family of neuroendocrine peptides consists of NPY, PYY (peptide YY) and PP (pancreatic polypeptide). Several receptors have been characterized pharmacologically of which three have now been cloned. All three belong to the superfamily of receptors that couple to G proteins and all three cause inhibition of cAMP accumulation. Receptor subtypes Y1 and Y2 bind both NPY and PYY. Surprisingly, Y1 and Y2 share only 31% overall sequence identity, the lowest percentage reported for receptors that bind the same peptide ligand. Nevertheless, each subtype is 94% identical between human and rat, suggesting a slow rate of change. These observations suggest that Y1 and Y2 started to diverge from one another very long ago, possibly before the origin of vertebrates. The PP receptor, called PP1 or Y4, is 42% identical to the Y1 receptor (57% in the transmembrane regions) and is one of the most rapidly evolving receptors with only 75% overall identity between man and rat. Interestingly, this receptor's preferred ligand, PP, also evolves extremely rapidly. The PP receptor also differs between man and rat in tissue distribution and binding properties. The Y1 and PP receptors bind to both termini of their ligands whereas Y2 mainly interacts with the C-terminal part. Thus, within the same family there are highly conserved receptors and peptide ligands as well as one rapidly evolving receptor and ligand.
Amino Acid Sequence↗
The cloned rat pancreatic polypeptide receptor exhibits profound differences to the orthologous receptor.
Pancreatic polypeptide (PP) is produced in the islets of Langerhans and released in response to meals. It belongs to a family of peptides that also includes neuropeptide Y and peptide YY. In the present communication, we describe a rat receptor with high affinity for PP, therefore named PP1. Clones for the PP1 receptor were obtained by PCR using sequence information for the neuropeptide Y receptor Y1 from several species. The PP1 receptor has 46% overall amino acid sequence identity to the rat Y1 receptor and 56% identity in the transmembrane regions. The PP1 receptor displays a pharmacological profile that is distinct from previously described neuropeptide Y-family receptors. In competition with iodinated bovine PP, it binds rat PP with an affinity (K(i)) of 0.017 nM, while the affinities for peptide YY and neuropeptide Y are substantially lower with K(i) values of 162 and 192 nM, respectively. In stably transfected CHO cells, the PP1 receptor inhibits forskolin-stimulated cAMP synthesis. Northern blot hybridizations to a panel of mRNAs detected transcripts in testis and lung. A faint band was seen in colon and total brain. In contrast, the human receptor is expressed primarily in colon and small intestine. Whereas rat and human PP1 bind PP with the same affinity, the rat receptor has much lower affinity than its human ortholog for peptide YY and neuropeptide Y. Interestingly, the amino acid sequence identity between rat and human PP1 is only 75%. Thus, the sequence, the tissue distribution, and the binding profile of the PP1 receptor differ considerably between rat and human.
Amino Acid Sequence↗
Lack of biological significance in the 'linguistic features' of noncoding DNA--a quantitative analysis.
Recently, the application of two statistical methods (related to Zipf's distribution and Shannon's redundancy), called 'linguistic' tests, to the primary structure of DNA sequences of living organisms has excited considerable interest. Of particular importance is the claim that noncoding DNA sequences in eukaryotes display specific 'linguistic' features, being reminiscent of natural languages. Furthermore, this implies that noncoding regions of DNA may carry some new, thus far unknown, biological information which is revealed by these tests. In this paper these claims are tested quantitatively. With the aid of computer simulations of natural DNA sequences, and by applying the same 'linguistic' tests to both natural and artificial sequences, we investigate in detail the reasons of the appearance of the claimed 'linguistic' features and the associated differences between coding and noncoding DNAs. The presented results show quantitatively that the 'linguistic' tests failed to reveal any new biological information in (noncoding or coding) DNA.
Base Composition↗
Evolution of neuropeptide Y, peptide YY and pancreatic polypeptide.
The neuropeptide Y family of peptides consists of neuropeptide Y (NPY), which is expressed in the central and peripheral nervous systems, and peptide YY (PYY) and pancreatic polypeptide (PP) which are gut endocrine peptides. All three peptides are 36 amino acids long and act on G-protein-coupled receptors. NPY and PYY are present in all vertebrates, whereas PP probably arose as a copy of PYY in an early tetrapod ancestor. NPY is one of the most conserved peptides during evolution and no gnathostome (jawed) species differs from the ancestral gnathostome sequence at more than five positions. PYY is more variable, particularly in mammals which have nine differences to the gnathostome ancestor. PP may be the most rapidly evolving neuroendocrine peptide among tetrapods with only 50% identity between mammals, birds, and amphibians. Ancestral gnathostome NPY and PYY seem to have differed at only four positions, suggesting that the gene duplication occurred shortly before the appearance of the gnathostomes. The two peptides differ from one another at 9-12 positions in tetrapod species and share at least two receptor subtypes in mammals. In bony and cartilaginous fishes, NPY and PYY have only 5-6 differences which, together with more extensive neuronal localization of PYY, indicate an even greater functional overlap between the two peptides in these animal groups. The emergence of sequence information for several receptor subtypes from various species will shed additional light on the evolution of the functions of the NPY-family peptides.
Amino Acid Sequence↗
Characterization of the peptide binding requirements for the cloned human pancreatic polypeptide-preferring receptor.
Traditionally, neuropeptide Y (NPY) receptors have been divided into Y1 and Y2 subtypes based on peptide pharmacology and synaptic localization. Other receptor subtypes have been proposed based on preferences for NPY, peptide YY (PYY), or pancreatic polypeptide (PP). Recently, we discovered a novel human member of this receptor family exhibiting high affinity for PP and PYY. In the current study, we expressed a DNA clone encoding this human PP-preferring receptor [hPP1 (or Y4)] in Chinese hamster ovary cells and performed a peptide structure-activity study. [125I]pPYY bound to homogenates of hPP1-Chinese hamster ovary cells with a Kd of 0.064 +/- 0.006 nM and a Bmax of 244 +/- 12 fmol/mg protein. Human PP inhibited binding with a Ki of 0.023 nM, whereas human PYY (Ki = 0.31 nM) and human NPY Ki = 12 nM) were significantly less potent. Rat, porcine, and bovine PP inhibited binding with similar affinities to human PP, whereas avian PP was substantially less potent (Ki = 1 nM). Deletion of the first four amino acids reduced the affinity of bovine PP to 1 nM. Carboxyl-terminal fragments of NPY and PYY also had reduced potency compared with the native peptides. In addition, deletion of Tyr36-amide produced a substantial reduction in affinity. Pro34-substituted NPY and PYY had modestly increased affinity compared with the native peptides, although Gln34-bPP had similar affinity compared with bovine PP. The carboxyl-terminally derived Y1 antagonist 1229U91 was a very potent (Ki = 0.042 nM) inhibitor of binding to hPP1. Thus, the carboxyl-terminal region of PP seems to be the most important part of the peptide for high affinity binding to hPP1. A few key residues (amino acids 2 and 3) in the amino-terminal region of PP contribute to the high affinity of the native peptide. Thus, features required for peptide recognition by the hPP1 receptor seem to be distinct from the Y1 and Y2 receptor.
Amino Acid Sequence↗
Cloning of a human receptor of the NPY receptor family with high affinity for pancreatic polypeptide and peptide YY.
Neuropeptide Y (NPY), peptide YY (PYY), and pancreatic polypeptide (PP) are structurally related peptides found in all higher vertebrates. NPY is expressed exclusively in neurons, whereas PYY and PP are produced primarily in gut endocrine cells. Several receptor subtypes have been identified pharmacologically, but only the NPY/PYY receptor of subtype Y1 has been cloned. This is a heptahelix receptor that couples to G proteins. We utilized Y1 sequence information from several species to clone a novel human receptor with 43% amino acid sequence identity to human Y1 and 53% identity in the transmembrane regions. The novel receptor displays a pharmacological profile that distinguishes it from all previously described NPY family receptors. It binds PP with an affinity (Ki) of 13.8 pM, PYY with 1.44 nM, and NPY with 9.9 nM. Because these data may identify the receptor as primarily a PP receptor, we have named it PP1. In stably transfected Chinese hamster ovary cells the PP1 receptor inhibits forskolin-stimulated cAMP synthesis. Northern hybridization detected mRNA in colon, small intestine, pancreas, and prostate. As all three peptides are present in the gut through either endocrine release or innervation, all three peptides may be physiological ligands to the novel NPY family receptor PP1.
Amino Acid Sequence↗