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Frohman LA, Kineman RD. Growth Hormone‐Releasing Hormone: Discovery, Regulation, and Actions. Compr Physiol 2011. [DOI: 10.1002/cphy.cp070508] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Liu D, O'Leary B, Iruthayanathan M, Love-Homan L, Perez-Hernandez N, Olivo HF, Dillon JS. Evaluation of a novel photoactive and biotinylated dehydroepiandrosterone analog. Mol Cell Endocrinol 2010; 328:56-62. [PMID: 20670672 DOI: 10.1016/j.mce.2010.07.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2010] [Revised: 06/23/2010] [Accepted: 07/01/2010] [Indexed: 12/01/2022]
Abstract
To characterize the cell surface receptor for dehydroepiandrosterone (DHEA), we synthesized a DHEA analog containing biotin and benzophenone groups (DHEA-BP-Bt). DHEA-BP-Bt was equipotent with DHEA in competing with [(3)H]DHEA for binding to solubilized plasma membranes of bovine aortic endothelial cells (BAEC). Additionally, DHEA-BP-Bt pre-conjugated to avidin and immobilized on agarose, also inhibited plasma membrane binding of [(3)H]DHEA. Furthermore, DHEA-BP-Bt activated endothelial nitric oxide synthase, similar to DHEA. Confocal micrographs showed that, upon photoirradiation, DHEA-BP-Bt bound to sites on the cell surface of BAEC in a DHEA inhibitable manner. Finally, DHEA-BP-Bt bound specifically to proteins of approximately 55 kDa and 80 kDa, either when live cells were UV irradiated with the analog and plasma membrane proteins separated by SDS-PAGE or in a ligand blot analysis. These data confirm the successful synthesis of a photoactive, biotinylated DHEA analog which is capable of cross-linking to and identifying plasma membrane DHEA binding sites and which will allow us to further purify this receptor.
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Affiliation(s)
- Dongmin Liu
- Research Service, Department of Veterans Affairs Medical Center, Iowa City, IA, USA
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Du AT, Onan D, Dinh DT, Lew MJ, Ziogas J, Aguilar MI, Pattenden LK, Thomas WG. Ligand-supported purification of the urotensin-II receptor. Mol Pharmacol 2010; 78:639-47. [PMID: 20647393 DOI: 10.1124/mol.110.065151] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
A crucial limitation for structural and biophysical analysis of G protein-coupled receptors (GPCRs) is the inherent challenge of purifying and stabilizing these receptors in an active (agonist-bound) conformation. Peptide ligands, such as the vasoactive, cyclic hormone urotensin-II (U-II), may provide new purification tools, via high affinity, pseudo-irreversible binding suitable for ligand-based affinity purification. We show that the U-II receptor (UT) is resistant to desensitization as a result of low phosphorylation and diminished endocytosis. UT also displays an unusual proclivity to remain active with vasoconstriction sustained despite extensive washout of the ligand. To exploit these properties for ligand-supported purification, we modified the U-II ligand by attaching a biotin moiety and spacer arm to the N terminus, creating a novel affinity ligand (Bio-U-II) to interface with streptavidin media. Bio-U-II bound to UT with pharmacological properties analogous to those of the unmodified U-II ligand (high-affinity, pseudo-irreversible binding). The prebinding of Bio-U-II to UT (before exposure to detergent) facilitated specific capture of UT by stabilizing the receptor structure during solubilization with detergent. Solubilization of UT with the most compatible detergent, n-dodecyl β-d-maltoside, was dependent on the critical micelle concentration, and Gα(q/11) protein was copurified with captured Bio-U-II-UT complexes. Furthermore, captured Bio-U-II-UT complexes were resistant to dissociation at elevated temperatures, suggesting that UT is relatively thermostable, making it an ideal candidate for future structural and biophysical studies. This work demonstrates the utility of pseudo-irreversible ligands to support the purification of a GPCR during detergent extraction, resulting in the first successful purification of the UT.
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Affiliation(s)
- Ann T Du
- Department of Biochemistry and Molecular Biology, Monash University, Melbourne, Australia
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Olivo HF, Perez-Hernandez N, Liu D, Iruthayanathan M, O'Leary B, Homan LL, Dillon JS. Synthesis and application of a photoaffinity analog of dehydroepiandrosterone (DHEA). Bioorg Med Chem Lett 2009; 20:1153-5. [PMID: 20031404 DOI: 10.1016/j.bmcl.2009.12.019] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2009] [Revised: 12/01/2009] [Accepted: 12/03/2009] [Indexed: 11/30/2022]
Abstract
We have synthesized an analog of dehydroepiandrosterone (DHEA, 1) containing both a benzophenone (BP) and a biotin (Bt) group (DHEA-BP-Bt, 8). Compound 8 was prepared by functionalization on C-17 of 1. Biocytin was reacted with 4-benzoylbenzoic acid and the product was condensed with 1 containing a diamine-hexane linker. We detected specific protein bands of approximately 55, 80, and 150 kDa by SDS-PAGE analysis of vascular endothelial cell plasma membranes which had been photoirradiated in the presence of 8.
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Affiliation(s)
- Horacio F Olivo
- Division of Medicinal and Natural Products Chemistry, College of Pharmacy, University of Iowa, Iowa City, IA 52242, USA.
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Boulanger L, Girard N, Strecko J, Gaudreau P. Characterization of a growth hormone-releasing hormone binding site in the rat renal medulla. Peptides 2002; 23:1187-94. [PMID: 12126750 DOI: 10.1016/s0196-9781(02)00029-3] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Receptor binding analysis was performed in the renal medulla from 2-month-old rats, an extrapituitary tissue containing the highest level of GHRH receptor mRNA. At 4 degrees C, in the presence of a cocktail of protease inhibitors, binding of [125I-Tyr(10)]hGHRH (1-44)NH(2) to medullary homogenates was specific, time-dependent, reversible and saturable (K(d): 28 nM; B(max): 30 fmol/mgprot.). In these experimental conditions, no change of binding parameters could be detected in the course of aging. The structure-affinity profile was different in the two tissues and chemical cross-linking revealed the presence of 65-, 55- and 38-kDa 125I-GHRH-labeled complexes in the renal medulla compared to 65-, 47- and 28-kDa radioactive complexes in the anterior pituitary. It is suggested that GHRH binding sites, and possibly the receptor, may be different in the two tissues.
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Affiliation(s)
- Luce Boulanger
- Laboratory of Neuroendocrinology of Aging, Department of Medicine, CHUM Research Center, Notre-Dame Hospital, University of Montreal, 1560 East Sherbrooke Street, Que., H2L 4M1, Montreal, Canada
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Boulanger L, Girard N, Strecko J, Gaudreau P. Characterization of a growth hormone-releasing hormone binding site in the rat renal medulla. Peptides 2002; 23:43-50. [PMID: 11814616 DOI: 10.1016/s0196-9781(01)00577-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
Abstract
Receptor binding analysis was performed in the renal medulla from 2-month-old rats, an extrapituitary tissue containing the highest level of GHRH receptor mRNA. At 4 degrees C, in the presence of a cocktail of protease inhibitors, binding of [125I-Tyr(10)]hGHRH NH(2) to medullary homogenates was specific, time-dependent, reversible and saturable (K(d): 28 nM; B(max): 30 fmol/mg prot.). In these experimental conditions, no change of binding parameters could be detected in the course of aging. The structure-affinity profile was different in the two tissues and chemical cross-linking revealed the presence of 65-, 55- and 38-kDa 125I-GHRH-labeled complexes in the renal medulla compared to 65-, 47- and 28-kDa radioactive complexes in the anterior pituitary. It is suggested that GHRH binding sites, and possibly the receptor, may be different in the two tissues.
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Affiliation(s)
- Luce Boulanger
- Laboratory of Neuroendocrinology of Aging, CHUM Research Center, Notre-Dame Hospital and Department of Medicine, University of Montreal, Montreal, Quebec, Canada
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Horikawa R, Gaylinn BD, Lyons CE, Thorner MO. Molecular cloning of ovine and bovine growth hormone-releasing hormone receptors: the ovine receptor is C-terminally truncated. Endocrinology 2001; 142:2660-8. [PMID: 11356717 DOI: 10.1210/endo.142.6.8210] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
To provide information about species differences in GH-releasing hormone (GHRH) receptors useful for studies of receptor-ligand binding properties and receptor function, we have cloned the ovine and bovine pituitary GHRH receptors (GHRHRs). The ovine receptor (oGHRHR) was cloned from a pituitary complementary DNA library and encodes a protein that is similar to that of porcine, human, rat, and mouse with, respectively, 84.3, 80.7, 75.9, and 74.0% amino acid identity. Surprisingly, oGHRHR has a 16 amino acid truncation at its carboxyl-terminal end when compared with GHRHRs from other known mammals. RT-PCR using pooled pituitary RNA from a different population of sheep could detect only truncated receptor. Bovine GHRHR (bGHRHR) was cloned by RT-PCR and shows 92.5% amino acid sequence identity with oGHRHR, but has no truncation. Genomic sequencing of the appropriate region of goat receptor intron 13 showed that the caprine receptor shares the same truncation seen in sheep. Photoaffinity cross-linking of GHRH to ovine and bovine pituitary membranes confirms that the native ovine pituitary GHRHR protein is smaller by the amount predicted by the cloned sequences. The truncation did not affect GHRH binding as oGHRHR, bGHRHR, human GHRHR, and human GHRHR, which was truncated by site-directed mutagenesis to match the oGHRHR, all showed comparable GHRH binding affinity when expressed in transfected cell lines. In contrast, the ovine and truncated human receptors demonstrated enhanced sensitivity for GHRH stimulation of cAMP (lowered ED(50)) relative to hGHRHR and bGHRHR. This suggests that this C-terminal domain acts to inhibit cAMP signaling possibly through a role in receptor down regulation.
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MESH Headings
- Amino Acid Sequence
- Animals
- Cattle/genetics
- Cloning, Molecular
- Cross-Linking Reagents
- Cyclic AMP/metabolism
- DNA, Complementary/chemistry
- DNA, Complementary/isolation & purification
- Growth Hormone-Releasing Hormone/metabolism
- Growth Hormone-Releasing Hormone/pharmacology
- Humans
- Molecular Sequence Data
- Photoaffinity Labels
- Receptors, Neuropeptide/chemistry
- Receptors, Neuropeptide/genetics
- Receptors, Neuropeptide/metabolism
- Receptors, Pituitary Hormone-Regulating Hormone/chemistry
- Receptors, Pituitary Hormone-Regulating Hormone/genetics
- Receptors, Pituitary Hormone-Regulating Hormone/metabolism
- Reverse Transcriptase Polymerase Chain Reaction
- Sequence Alignment
- Sequence Analysis, DNA
- Sheep/genetics
- Signal Transduction
- Species Specificity
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Affiliation(s)
- R Horikawa
- Division of Endocrinology and Metabolism, Department of Medicine, University of Virginia Health System, Charlottesville, Virginia 22908, USA.
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Elliott JT, Hoekstra WJ, Derian CK, Addo MF, Maryanoff BE, Ahern DG, Prestwich GD. Tritiated photoactivatable analogs of the native human thrombin receptor (PAR-1) agonist peptide, SFLLRN-NH2. THE JOURNAL OF PEPTIDE RESEARCH : OFFICIAL JOURNAL OF THE AMERICAN PEPTIDE SOCIETY 2001; 57:494-506. [PMID: 11437953 DOI: 10.1034/j.1399-3011.2001.00857.x] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Six photoactivatable analogs of the human thrombin receptor activating peptide (TRAP), SFLLRN-NH2, were synthesized by substituting the photoactive amino acid, p-benzoylphenylalanine (Bpa), into each position of the peptide sequence. Platelet aggregation assays indicated that the peptides with Bpa substitutions at positions 3 to 6 retained agonist activity. These peptides were prepared in tritiated form as potential thrombin receptor photoaffinity labels. The [3H]Bpa-containing analogs were constructed by resynthesizing the peptides with the amino acid, 4-benzoyl-2',5'-dibromophenylalanine (Br2Bpa), and subjecting the purified peptides to Pd-catalyzed tritiodebromination. The radiochemical yields for the reductive tritiation were < 2% for peptides with [3H]Bpa in the third and fourth positions, and between 7 and 16% for the peptides with substitutions at the fifth and sixth positions. The low yields were due to over-reduction of the Bpa carbonyl group and nonspecific degradation during reductive tritiation. This report describes the first use of Br2Bpa for the preparation of tritiated photoactivatable peptides.
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Affiliation(s)
- J T Elliott
- Department of Physiology and Biophysics, The University of at Stony Brook, Stony Brook, New York, USA
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Petersenn S, Schulte HM. Structure and function of the growth-hormone-releasing hormone receptor. VITAMINS AND HORMONES 2000; 59:35-69. [PMID: 10714236 DOI: 10.1016/s0083-6729(00)59003-7] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Growth-hormone-releasing hormone (GHRH) stimulates growth hormone (GH) secretion and GH synthesis and is also thought to cause somatotroph proliferation. Specific high-affinity binding sites for GHRH have been demonstrated on pituitary membranes using iodinated GHRH analogs. The complementary DNA encoding for the human GHRH receptor (GHRH-R) was recently cloned. The open reading frame was shown to extend 1269 bp and thus to encode a protein of 423 amino acids with a predicted molecular weight of 47 kDa. Expression is restricted to specific tissues. Analysis of the genomic structure revealed that the human GHRH-R gene spans 15 kb and consists of 13 exons. The 5'-flanking region of the human GHRH-R gene was recently characterized. Transcriptional regulation of the GHRH-R is discussed in this review. Mechanisms of signal transduction for control of GH transcription and secretion are presented. Furthermore, the role of the GHRH-R in proliferation and differentiation of the somatotrophic pituitary cell as well as in disease is examined.
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Affiliation(s)
- S Petersenn
- IHF Institute for Hormone and Fertility Research, University of Hamburg, Germany
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