Growth hormone (GH)-releasing hormone increases the expression of the dominant-negative GH isoform in cases of isolated GH deficiency due to GH splice-site mutations

Petkovic, Vibor; Godi, Michela; Lochmatter, Didier; Eblé, Andrée; Flück, Christa E; Robinson, Iain C; Mullis, Primus E (2010). Growth hormone (GH)-releasing hormone increases the expression of the dominant-negative GH isoform in cases of isolated GH deficiency due to GH splice-site mutations. Endocrinology, 151(6), pp. 2650-8. Chevy Chase, Md.: Endocrine Society 10.1210/en.2009-1280

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An autosomal dominant form of isolated GH deficiency (IGHD II) can result from heterozygous splice site mutations that weaken recognition of exon 3 leading to aberrant splicing of GH-1 transcripts and production of a dominant-negative 17.5-kDa GH isoform. Previous studies suggested that the extent of missplicing varies with different mutations and the level of GH expression and/or secretion. To study this, wt-hGH and/or different hGH-splice site mutants (GH-IVS+2, GH-IVS+6, GH-ISE+28) were transfected in rat pituitary cells expressing human GHRH receptor (GC-GHRHR). Upon GHRH stimulation, GC-GHRHR cells coexpressing wt-hGH and each of the mutants displayed reduced hGH secretion and intracellular GH content when compared with cells expressing only wt-hGH, confirming the dominant-negative effect of 17.5-kDa isoform on the secretion of 22-kDa GH. Furthermore, increased amount of 17.5-kDa isoform produced after GHRH stimulation in cells expressing GH-splice site mutants reduced production of endogenous rat GH, which was not observed after GHRH-induced increase in wt-hGH. In conclusion, our results support the hypothesis that after GHRH stimulation, the severity of IGHD II depends on the position of splice site mutation leading to the production of increasing amounts of 17.5-kDa protein, which reduces the storage and secretion of wt-GH in the most severely affected cases. Due to the absence of GH and IGF-I-negative feedback in IGHD II, a chronic up-regulation of GHRH would lead to an increased stimulatory drive to somatotrophs to produce more 17.5-kDa GH from the severest mutant alleles, thereby accelerating autodestruction of somatotrophs in a vicious cycle.

Item Type:

Journal Article (Original Article)

Division/Institute:

04 Faculty of Medicine > Department of Gynaecology, Paediatrics and Endocrinology (DFKE) > Clinic of Paediatric Medicine
04 Faculty of Medicine > Pre-clinic Human Medicine > BioMedical Research (DBMR) > Unit Childrens Hospital > Forschungsgruppe Endokrinologie / Diabetologie / Metabolik (Pädiatrie)

UniBE Contributor:

Petkovic, Vibor; Lochmatter, Didier; Eblé, Andrée; Flück, Christa and Mullis, Primus-Eugen

ISSN:

0013-7227

Publisher:

Endocrine Society

Language:

English

Submitter:

Factscience Import

Date Deposited:

04 Oct 2013 14:07

Last Modified:

06 Dec 2013 13:19

Publisher DOI:

10.1210/en.2009-1280

PubMed ID:

20351314

Web of Science ID:

000277948800027

URI:

https://boris.unibe.ch/id/eprint/161 (FactScience: 196590)

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