Studies with a growth hormone antagonist and dual-fluorescent confocal microscopy demonstrate that the full-length human growth hormone receptor, but not the truncated isoform, is very rapidly internalized independent of Jak2-Stat5 signaling
| Autor: | Sue Justice, M. Maamra, Sigward Von Laue, Joëlle Finidori, Richard J. Ross, Sylvie Simon, Jonathan Webster, Steven K. Dower |
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| Rok vydání: | 1999 |
| Předmět: |
Gene isoform
medicine.medical_specialty Growth-hormone-releasing hormone receptor education Golgi Apparatus Growth hormone receptor Biology Biochemistry law.invention Confocal microscopy law Internal medicine medicine Humans Protein Isoforms Receptor Molecular Biology Microscopy Confocal Human Growth Hormone Antagonist Cell Biology Receptors Somatotropin Endocrinology Microscopy Fluorescence Hormone receptor hormones hormone substitutes and hormone antagonists Hormone |
| Zdroj: | The Journal of biological chemistry. 274(21) |
| ISSN: | 0021-9258 |
| Popis: | We have investigated trafficking of two negative regulators of growth hormone receptor (GHR) signaling: a human, truncated receptor, GHR1-279, and a GH antagonist, B2036. Fluorescent-labeled growth hormone (GH) was rapidly internalized by the full-length GHR, with80% of the hormone internalized within 5 min of exposure to GH. In contrast,5% of labeled GH was internalized by cells expressing truncated GHR1-279. Using another truncated receptor, GHR1-317 fused to enhanced green fluorescent protein (EGFP), we have exploited fluorescence energy transfer to monitor the trafficking of ligand-receptor complexes. The data confirmed that internalization of this truncated receptor is very inefficient. It was possible to visualize the truncated GHR1-317-EGFP packaged in the endoplasmic reticulum, its rapid movement in membrane bound vesicles to the Golgi apparatus, and subsequent transport to the cell membrane. The GH antagonist, B2036, blocked Jak2-Stat5-mediated GHR signaling but was internalized with a similar time course to native GH.1) demonstrate the rapid internalization of GH when studied under physiological conditions; 2) confirm the hypothesis that internalization of cytoplasmic domain truncated human GHRs is very inefficient, which explains their dominant negative action; and 3) show that the antagonist action of B2036 is independent of receptor internalization. |
| Databáze: | OpenAIRE |
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