共查询到20条相似文献,搜索用时 15 毫秒
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Hiroyuki Kaiya Tsukasa Mori Mikiya Miyazato Kenji Kangawa 《Comparative biochemistry and physiology. Part A, Molecular & integrative physiology》2009,153(4):438-450
Ghrelin, a GH-releasing and appetite-regulating peptide that is released from the stomach is an endogenous ligand for growth hormone secretagogue-receptor (GHS-R). Two types of GHS-R are accepted to be present, a functional GHS-R1a and GHS-R1b with unknown function. In this study, we identified cDNA that encodes protein with close sequence similarity to GHS-R and exon–intron organization of the GHS-R genes in rainbow trout, Oncorhynchus mykiss. Two variants of GHS-R1a proteins with 387-amino acids, namely DQTA/LN-type and ERAT/IS-type, were identified. In 3'-RACE PCR and genomic PCR, we also identified three GHS-R1b orthologs that are consisted of 297- or 300-amino acids with different amino acid sequence at the C-terminus, in addition to the DQTA/LN-type and ERAT/IS-type variations. Genomic PCR revealed that the genes are composed of two exons separated by an intron, and that two GHS-R1a and three GHS-R1b variants are generated by three distinct genes. GHS-R1a and GHSR-1b mRNA were predominantly expressed in the pituitary, followed by the brain. Identified DQTA/LN-type or ERAT/IS-type GHS-R1a cDNA was transfected into mammalian cells, and intracellular calcium ion mobilization assay was carried out. However, we did not find any response to rat ghrelin and a homologous ligand, des-VRQ trout ghrelin, of either receptor in vitro. We found that unexpected mRNA splicing had occurred in the transfected cells, suggesting that the full-length, functional receptor protein might not be generated in the cells. Gene structure and characterization of protein sequence identified in this study were closely similar to other GHS-R, but to conclude that it is a GHS-R for rainbow trout, further study is required to confirm activation of GHS-R1a by ghrelin or GHS. Thus we designated the identified receptor proteins in this study as GHS-R-like receptor (GHSR-LR). 相似文献
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生长激素促释放剂受体配体的研究进展 总被引:2,自引:0,他引:2
生长激素促释放剂是一种合成的小分子化合物,它通过生长激素促释放剂受体而起作用,该受体是一种新的G蛋白偶联受体。以前曾认为生长激素促释放剂受体是一种孤儿受体,直到近年来从人和鼠的胃中鉴定到Ghrelin的存在,而改变了这种看法。Ghrelin是包含28个氨基酸残基的肽,在3号位的丝氨酸位点有辛酰化基团。该肽是在X/A样细胞分泌颗粒中发现的,Ghrelin的发现表明促垂体分泌生长激素可能不止受到来自下丘脑的生长激素释放激素的调节,同时还可能受到来自胃和下丘脑的Ghrelin的调节。 相似文献
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Petersenn S 《Hormone research》2002,58(Z3):56-61
The pulsatile release of growth hormone (GH) by the anterior pituitary is stimulated by small synthetic molecules termed GH secretagogues (GHS). The receptor for GHS (GHS-R) belongs to the family of G-protein-coupled receptors. An endogenous specific ligand of 28 amino acids has recently been purified from rat stomach, it has been termed 'ghrelin'. Ghrelin demonstrates potent and reproducible GH-releasing activity, as well as significant prolactin-, ACTH- and cortisol-releasing activity. However, its major physiological relevance may relate to energy homeostasis. Peripheral daily administration of ghrelin caused weight gain by reducing fat utilization in mice and rats. In man, intravenous ghrelin was shown to stimulate food intake. The pathophysiological role and the potential clinical use of ghrelin are reviewed. 相似文献
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F Chen Z Selinger P Marks G Belinsky A H Tashjian 《Biochemical and biophysical research communications》2001,285(3):742-750
Despite attempts in several laboratories, it has been difficult to prepare antiserum to the thyrotropin-releasing hormone receptor (TRHR). We have prepared a polyclonal anti-rat TRHR antiserum by immunization of rabbits with a synthetic peptide corresponding to the C-terminus of the TRHR. The specificity of the antiserum was assessed by enzyme-linked immunosorbent assay. The affinity-purified antibody recognized a major broad band at 50-60 kDa and a minor broad band at 100-120 kDa in Western blot analysis of membrane proteins from TRHR-transfected, but not control, HEK293t cells. Binding to both bands was abolished by preincubation with the immunizing peptide but not control peptide. The approach was repeated with rat pituitary F4C1 cells, which lack endogenous TRHRs; membranes from F4C1 cells transfected with TRHR cDNA, but not control cells, showed specific binding by Western blot. Using laser confocal microscopy, the TRHR was visualized on the plasma membrane of transfected, but not control, F4C1 cells. Similar confocal findings were observed in TRHR-transfected HEK293t cells. Within 5 min after TRH addition, the TRHR signal translocated from the plasma membrane to the cytoplasm of F4C1 cells transfected with TRHR cDNA. Ten minutes after TRH addition, the TRHR signal formed aggregates in the cytoplasm. Thirty minutes after TRH treatment, both cytoplasmic and plasma membrane localizations were observed, suggesting recycling of some TRHRs back to the plasma membrane. These observations are consistent with our previous findings using an epitope-tagged TRHR. In conclusion, we have prepared an antiserum that recognizes the native TRHR by Western blot analysis and confocal microscopy. 相似文献
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Endocrine and non-endocrine actions of ghrelin 总被引:5,自引:0,他引:5
Ghrelin is a 28-amino-acid peptide predominantly produced by the stomach. Substantially lower amounts were detected in bowel, pancreas, kidneys, the immune system, placenta, testes, pituitary, and hypothalamus. Ghrelin displays strong growth hormone (GH)-releasing action mediated by the activation of the so-called GH secretagogue (GHS) receptor (GHS-R) type 1a. GHS-R are concentrated in the hypothalamus-pituitary unit but are also distributed in other central and peripheral tissues. Apart from the potent GH-releasing action, ghrelin has other actions including stimulation of lactotroph and corticotroph function, influence on the pituitary gonadal axis, stimulation of appetite, control of energy balance, influence on sleep and behavior, control of gastric motility and acid secretion, influence on exocrine and endocrine pancreatic function as well as on glucose metabolism, cardiovascular actions and modulation of proliferation of neoplastic cells, as well as of the immune system. The discovery of ghrelin opened many new perspectives of research in neuroendocrinology and metabolism, and even also in other fields of internal medicine as gastroenterology, immunology, oncology and cardiology. The possibility that ghrelin and/or GHS analogs, acting as either agonists or antagonists on different activities, might have clinical impact is obviously suggested and is receiving great attention. 相似文献
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Schweppe RE Melton AA Brodsky KS Aveline LD Resing KA Ahn NG Gutierrez-Hartmann A 《The Journal of biological chemistry》2003,278(19):16863-16872
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Kageyama H Funahashi H Hirayama M Takenoya F Kita T Kato S Sakurai J Lee EY Inoue S Date Y Nakazato M Kangawa K Shioda S 《Regulatory peptides》2005,126(1-2):67-71
Ghrelin, a novel peptide isolated from stomach tissue of rats and humans, has been identified as the endogenous ligand for the growth hormone secretagogue receptor (GHS-R). In addition to its secretion from the stomach, ghrelin is also expressed in the hypothalamic arcuate nucleus, intestine, kidney, placenta, and pancreas. GHS-R mRNA, on the other hand, is expressed in the hypothalamus, pituitary, heart, lung, liver, pancreas, stomach, intestine, and adipose tissue. Ghrelin is considered to have important roles in feeding regulation and energy metabolism as well as in the release of growth hormone (GH). Recent physiological experiments on the pancreas have shown that ghrelin regulates insulin secretion. However, sites of action of ghrelin in the pancreas are yet to be identified. In this study, to gain insight into the role of ghrelin in rat pancreatic islets, we used immunohistochemistry to determine the localization of ghrelin and GHS-R in islet cells. Double fluorescence immunohistochemistry revealed that weak GHS-R-like immunoreactivity was found in B cells containing insulin. GHS-R immunoreactivity overlapped that of glucagon-like immunoreactive cells. Moreover, both ghrelin and GHS-R-like immunoreactivities were detected mostly in the same cells in the periphery of the islets of Langerhans. These observations suggest that ghrelin is synthesized and secreted from A cells, and acts back on A cells in an autocrine and/or paracrine manner. In addition, ghrelin may act on B cells via GHS-R to regulate insulin secretion. 相似文献
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Yunxia Wang Charles S. Bockman Sandor Lovas Peter W. Abel Richard F. Murphy J. Michael Conlon 《Journal of neurochemistry》1993,61(4):1231-1235
Abstract: γ-Preprotachykinin mRNA is the most abundant tachykinin mRNA in rat tissues, but the pathway of posttranslational processing of its translation product is unknown. An antiserum was raised against the synthetic peptide Asp-Ala-Gly-His-Gly-Gln-lle-Ser-His [neuropeptide γ-(1-9)-peptide, equivalent to γ-preprotachykinin-(72-80)-peptide], that showed <1% reactivity with intact neuropeptide γ and other tachykinins. Neuropeptide γ-(1-9)-peptide was detected by radioimmunoassay in relatively high concentrations in extracts of regions of rat brain and gastrointestinal tract. These concentrations correlated with (r = 0.99), but were significantly (p < 0.05) less than, the concentrations of neurokinin A-like immunoreactivity. The neuropeptide γ-(1-9)-like immunoreactivity in an extract of rat brain was eluted from a reverse-phase HPLC column in a single fraction with the same retention time as synthetic neuropeptide γ-(1 -9)-peptide. The synthetic peptide did not contract or relax isolated rat trachea, superior mesenteric artery, stomach fundus, or ileum, and the peptide did not affect the ability of neuropeptide 7 to contract the rat fundus. It is concluded that, in rat tissues, Lys70 -Arg71 in 7-preprotachykinin is a major site of posttranslational processing, but the resulting product, neuropeptide γ-(1-9)-peptide, is neither an agonist nor an antagonist at the neurokinin-2 (NK-2) receptor. 相似文献
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Mondal MS Date Y Yamaguchi H Toshinai K Tsuruta T Kangawa K Nakazato M 《Regulatory peptides》2005,126(1-2):55-59
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High molecular weight forms of basic fibroblast growth factor recognized by a new anti-bFGF antibody 总被引:3,自引:0,他引:3
An antibody against basic fibroblasts growth factor (bFGF) was raised using purified bovine pituitary bFGF. Western blot analysis revealed immunoreactive bands at 18, 24, 30-33 and 46 kDa in immunoaffinity purified extracts of pituitary and adrenal gland using this antibody. A similar staining pattern was obtained with ovary extracts with the exception of the missing 18 kDa band. A second anti-bFGF antibody raised against a synthetic peptide comprising the 24 N-terminal amino acids of bFGF reacted with the 18 kDa and the 46 kDa band of immunoaffinity purified ovary and adrenal gland extracts. 相似文献
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D'Este L Casini A Kimura S Bellier JP Ito E Kimura H Renda TG 《Neurochemistry international》2011,58(5):605-611
Immunohistochemical techniques were used to study the distribution of cholinergic neurons containing choline acetyltransferase of the common type (cChAT), the synthetic enzyme of acetylcholine, in the central nervous system of the slug Limax maximus and Limax valentianus. Because the antiserum applied here was raised against a recombinant protein encoded by exons 7 and 8 of the rat gene for ChAT, three methods were used in order to validate antibody specificity for the Limax counterpart enzyme. Western blot combined with ChAT activity assay following native gel electrophoresis and immunoprecipitation analysis both indicated that immunoreactive Limax brain molecules were capable of synthesizing acetylcholine. Western blot after denatured gel electrophoresis of Limax brain extracts revealed a single band of about 67kDa. All findings obtained with these three methods clearly indicated that the antiserum effectively recognized Limax cChAT. 1400 neuronal cell bodies positive for cChAT, mainly small to medium-sized, were found in various brain regions in the buccal, cerebral, pleural, parietal, visceral and pedal ganglia. cChAT immunoreactive nerve fibers were distributed extensively in the neuropil, connectives and commissures of these central ganglia. The map of cChAT-positive cells provided here are valuable for understanding the cholinergic mechanism in the slug brain, as well as giving an important hint to clarifying the mechanisms of learning and memory in higher vertebrates including humans. 相似文献
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Rat ghrelin stimulates growth hormone and prolactin release in the tilapia,Oreochromis mossambicus 总被引:3,自引:0,他引:3
Recently, ghrelin (Ghr), a new peptide which specifically stimulates growth hormone (GH) release from the pituitary, was identified in the rat and human stomach. Ghrelin has been shown to stimulate GH release by acting through a growth hormone secretagogue (GHS) receptor in the rat. The present study describes the in vitro effect of rat Ghr on the release of GH and two forms of prolactin (PRL(177) and PRL(188)) in the tilapia, Oreochromis mossambicus. Rat Ghr stimulated the release of GH in a dose-related manner after 8 and 24 hr of incubation. Rat Ghr also significantly stimulated the release of PRL(177) and PRL(188) in a dose-related manner after 24 hr. Rat Ghr had no effect on the pituitary content of GH or PRL(188), but significantly increased PRL(177) content. These results show for the first time that rat Ghr significantly stimulates GH and PRL release in teleosts, and suggest that Ghr and a GHS receptor are present in fish. 相似文献
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Ghrelin--not just another stomach hormone 总被引:14,自引:0,他引:14
Growth hormone (GH) secretagogues (GHSs) are non-natural, synthetic substances that stimulate GH secretion via a G-protein-coupled receptor called the GHS-receptor (GHS-R). The natural ligand for the GHS-R has been identified recently; it is called ghrelin. Ghrelin and its receptor show a widespread distribution in the body; the greatest expression of ghrelin is in stomach endocrine cells. Administration of exogenous ghrelin has been shown to stimulate pituitary GH secretion, appetite, body growth and fat deposition. Ghrelin was probably designed to be a major anabolic hormone. Ghrelin also exerts several other activities in the stomach. The findings that ghrelin is produced in mucosal endocrine cells of the stomach and intestine, and that ghrelin is measurable in the general circulation indicate its hormonal nature. A maximal expression of ghrelin in the stomach suggests that there is a gastrointestinal hypothalamic-pituitary axis that influences GH secretion, body growth and appetite that is responsive to nutritional and caloric intakes. 相似文献
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Ghrelin is a 28-amino acid peptide hormone produced in the stomach. It binds to the growth hormone secretagogue receptor 1a (GHS-R1a), a class A G-protein-coupled receptor. In the present study, we describe the design, synthesis and characterization of a truncated, 18-amino acid analog of ghrelin conjugated to a fluorescent molecule, fluorocein isothiocyanate (FITC), through the addition of a lysine at its C terminus ([Dpr(octanoyl)(3), Lys(fluorescein)(19)]ghrelin(1-19)). Receptor binding affinity of this novel fluorescein-ghrelin(1-18) was similar to that of wild-type ghrelin and a synthetic GHS-R1a ligand, hexarelin. Live cell imaging in CHO/GHS-R1a cells demonstrated cell surface receptor labeling and internalization, and agonist activity of fluorescein-ghrelin(1-18) was confirmed by increased phosphorylation of ERK1/2. We also show that GHS-R1a protein is expressed primarily in the heart when compared to all other organs, suggesting high receptor density in the left ventricle. Finally, we demonstrate that fluorescein-ghrelin(1-18) binds specifically to heart tissue in situ, and its binding is displaced by both wt ghrelin and hexarelin. We have therefore developed a novel imaging probe, fluorescein-ghrelin(1-18), that can be used to image GHS-R1a in situ, for the purposes of investigating mechanisms of receptor trafficking or pharmacological agents that target GHS-R1a. 相似文献
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Aline Moulin Luc Brunel Damien Boeglin Luc Demange Johanne Ryan Céline M’Kadmi Séverine Denoyelle Jean Martinez Jean-Alain Fehrentz 《Amino acids》2013,44(2):301-314
Ghrelin is a 28-residue peptide acylated with an n-octanoyl group on the Ser 3 residue, predominantly produced by the stomach. Ghrelin displays strong growth hormone (GH) releasing activity, which is mediated by the activation of the so-called GH secretagogue receptor type 1a (GHS-R1a). Given the wide spectrum of biological activities of Ghrelin in neuroendocrine and metabolic pathways, many research groups, including our group, developed synthetic peptide, and nonpeptide GHS-R1a ligands, acting as agonists, partial agonists, antagonists, or inverse agonists. In this highlight article, we will focus on the discovery of a GHS-R1a antagonist compound, JMV 2959, which has been extensively studied in different in vitro and in vivo models. We will first describe the peptidomimetic approach that led us to discover this compound. Then we will review the results obtained with this compound in different studies in the fields of food intake and obesity, addictive behaviors, hyperactivity and retinopathy. 相似文献
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Morozumi N Hanada T Habara H Yamaki A Furuya M Nakatsuka T Inomata N Minamitake Y Ohsuye K Kangawa K 《Peptides》2011,32(5):1001-1007
Ghrelin is an endogenous ligand for growth hormone secretagogue receptor 1a (GHS-R1a), and consists of 28 amino acid residues with octanoyl modification at Ser3. The previous studies have revealed that N-terminal part of ghrelin including modified Ser3 is the active core for the activation of GHS-R1a. On the other hand, the role of C-terminal (8-28) region in ghrelin has not been clarified yet. In the present study, we prepared human ghrelin, C-terminal truncated ghrelin derivatives and anamorelin, a small molecular GHS compound which supposedly mimics the N-terminal active core, and examined GHS-R1a agonist activity in vitro, pharmacokinetic (PK) profile and growth hormone (GH) releasing activity in rats. All compounds demonstrated potent GHS-R1a agonist activities in vitro. Although the lack of C-terminal two amino acids did not modify PK profile and GH releasing activity, the deletion of C-terminal 8 and 20 amino acids affected them, and ghrelin(1-7)-Lys-NH2 exhibited very short plasma half-life and low GH releasing activity in vivo. In rat plasma, ghrelin(1-7)-Lys-NH2 was degraded more rapidly than ghrelin, suggesting that C-terminal part of ghrelin protected octanoylation of Ser3 from plasma esterases. Subdiaphragmatic vagotomy significantly attenuated GH response to ghrelin but not to anamorelin. These results suggest that the C-terminal part of ghrelin has an important role in the biological activity in vivo. We also found that ghrelin stimulated GH release mainly via a vagal nerve pathway but anamorelin augmented GH release possibly by directly acting on brain in rats. 相似文献
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T Endo M Ikeda M Ohmori E Anzai K Haraguchi T Onaya 《Biochemical and biophysical research communications》1992,187(2):887-893
We have produced rabbit antibody against a synthetic peptide corresponding to N-terminal region of the extracellular domain of human thyrotropin receptor (hTSH-R) (N peptide, aminoacid residues 29-57). Western blot analysis revealed that N-peptide antibody recognized recombinant hTSH-R stably expressing in CHO-K1 cells as a mol. wt. about 104 kDa regardless in the presence or absence of disulfide-reducing agent. The band was not detected in untransfected CHO-K1 cells and no band was also stained by the antibody absorbed with N-peptide. In a reducing condition, the antibody also bound the rat receptor from FRTL5 cells as the same molecular size (104 kDa). These results clearly indicate that TSH-R is composed of a single subunit and that two subunit model for the TSH-R may reflect artifactual proteolytic cleavage of the receptor during membrane preparation. 相似文献