Evaluation of the biological activity of a growth hormone (GH) mutant (R77C) and its impact on GH responsiveness and stature

Petkovic, Vibor; Besson, Amélie; Thevis, Mario; Lochmatter, Didier; Eblé, Andrée; Flück, Christa E; Mullis, Primus E (2007). Evaluation of the biological activity of a growth hormone (GH) mutant (R77C) and its impact on GH responsiveness and stature. Journal of clinical endocrinology and metabolism, 92(8), pp. 2893-901. Chevy Chase, Md.: Endocrine Society 10.1210/jc.2006-2238

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CONTEXT AND OBJECTIVE: A single missense mutation in the GH-1 gene converting codon 77 from arginine (R) to cysteine (C) yields a mutant GH-R77C peptide, which was described as natural GH antagonist. DESIGN, SETTING, AND PATIENTS: Heterozygosity for GH-R77C/wt-GH was identified in a Syrian family. The index patient, a boy, was referred for assessment of his short stature (-2.5 SD score) and partial GH insensitivity was diagnosed. His mother and grandfather were also carrying the same mutation and showed partial GH insensitivity with modest short stature. INTERVENTIONS AND RESULTS: Functional characterization of the GH-R77C was performed through studies of GH receptor binding and activation of Janus kinase 2/Stat5 pathway. No differences in the binding affinity and bioactivity between wt-GH and GH-R77C were found. Similarly, cell viability and proliferation after expression of both GH peptides in AtT-20 cells were identical. Quantitative confocal microscopy analysis revealed no significant difference in the extent of subcellular colocalization between wt-GH and GH-R77C with endoplasmic reticulum, Golgi, or secretory vesicles. Furthermore studies demonstrated a reduced capability of GH-R77C to induce GHR/GHBP gene transcription rate when compared with wt-GH. CONCLUSION: Reduced GH receptor/GH-binding protein expression might be a possible cause for the partial GH insensitivity with delay in growth and pubertal development found in our patients. In addition, this group of patients deserves further attention because they could represent a distinct clinical entity underlining that an altered GH peptide may also have a direct impact on GHR/GHBP gene expression causing partial GH insensitivity.

Item Type:

Journal Article (Further Contribution)

Division/Institute:

04 Faculty of Medicine > Department of Gynaecology, Paediatrics and Endocrinology (DFKE) > Clinic of Paediatric Medicine

UniBE Contributor:

Pegiazoglou, Ioannis; Lochmatter, Didier; Flück, Christa and Mullis, Primus-Eugen

ISSN:

0021-972X

ISBN:

17519310

Publisher:

Endocrine Society

Language:

English

Submitter:

Factscience Import

Date Deposited:

04 Oct 2013 14:55

Last Modified:

04 May 2014 23:16

Publisher DOI:

10.1210/jc.2006-2238

PubMed ID:

17519310

Web of Science ID:

000248570600011

URI:

https://boris.unibe.ch/id/eprint/23414 (FactScience: 41749)

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