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Design and characterization of a fluorescent ghrelin analog for imaging the growth hormone secretagogue receptor 1a
- Source :
- Regulatory Peptides. 172:69-76
- Publication Year :
- 2011
- Publisher :
- Elsevier BV, 2011.
-
Abstract
- 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.
- Subjects :
- Growth-hormone-releasing hormone receptor
Physiology
Clinical Biochemistry
Growth hormone secretagogue receptor
CHO Cells
Biology
Biochemistry
Mice
03 medical and health sciences
Cellular and Molecular Neuroscience
0302 clinical medicine
Endocrinology
Thyrotropin-releasing hormone receptor
Cricetinae
Enzyme-linked receptor
Animals
5-HT5A receptor
Receptors, Ghrelin
Glucagon-like peptide 1 receptor
030304 developmental biology
Insulin-like growth factor 1 receptor
Mitogen-Activated Protein Kinase 1
0303 health sciences
Mitogen-Activated Protein Kinase 3
Myocardium
digestive, oral, and skin physiology
Ghrelin
3. Good health
Mice, Inbred C57BL
Female
Fluorescein-5-isothiocyanate
hormones, hormone substitutes, and hormone antagonists
030217 neurology & neurosurgery
Subjects
Details
- ISSN :
- 01670115
- Volume :
- 172
- Database :
- OpenAIRE
- Journal :
- Regulatory Peptides
- Accession number :
- edsair.doi.dedup.....2575aeebce14f7f9ca4b67b09f14ed3e