SFEBES2014 Oral Communications Young Endocrinologists prize session (6 abstracts)
A loss-of-function mutation in the prolactin receptor causes familial hyperprolactinaemia
Caroline Gorvin 1 , Paul Newey 1 , Stephen Cleland 2 , Christian Willberg 3 , Marcus Bridge 4 , Mohammed Azharuddin 5 , Russell Drummond 5 , Anton van der Merwe 4 , Paul Klenerman 3 , Chas Bountra 6 & Rajesh Thakker 1
1Academic Endocrine Unit, Oxford Centre for Diabetes, Endocrinology and Metabolism, Oxford, UK; 2Hampshire Hospitals Foundation Trust, Hampshire, UK; 3Peter Medawar Building for Pathogen Research, Nuffield Department of Medicine, University of Oxford, Oxford, UK; 4Sir William Dunn School of Pathology, Oxford Molecular Pathology Institute, University of Oxford, Oxford, UK; 5Glasgow Royal Infirmary, Glasgow, UK; 6Structural Genomics Consortium, University of Oxford, Oxford, UK.
The prolactin receptor (PRLR) is a member of the class I cytokine receptor family that signals predominantly through the JAK2–STAT5 pathway. To date, PRLR mutations have not been established to be associated with any disorders. Here, we report a PRLR mutation (His188Arg) that caused familial hyperprolactinaemia in three sisters, two of whom presented with oligomenorrhea and one with infertility. The hyperprolactinaemia was not associated with pituitary tumours, which were sought for using MRI, or mutations of the multiple endocrine neoplasia type I (MEN1) or aryl-hydrocarbon-interacting protein (AIP) genes. We therefore hypothesised that the familial hyperprolactinaemia may be due to either abnormalities of the prolactin gene, with secretion of biologically inactive forms of prolactin, or prolactin insensitivity due to a PRLR mutation. DNA sequence analysis of leukocyte DNA did not identify any prolactin gene abnormalities, but revealed a heterozygous missense (His188Arg) mutation, involving an evolutionarily conserved residue in all three hyperprolactinaemic sisters. The functional effects of this mutation were investigated by expression in HEK293 cells and use of phosphorylation and STAT5 amplified luminescence proximity homogeneous (AlphaScreen) assays, as well as a STAT5-dependent gene expression assay that utilised a cytokine-inducible Src homology 2 domain containing protein (CISH) luciferase reporter. The PRLR Arg188 mutant abolished phosphorylation of JAK2 and STAT5 proteins, and STAT5 phosphorylation was demonstrated to be absent at all time-points (0–60 min) and prolactin concentrations (0–1000 ng/ml) when compared to the WT His188 PRLR. In addition, the PRLR Arg188 mutant abolished CISH reporter expression when compared to WT. Moreover, co-transfection of WT and mutant constructs also resulted in a reduction of CISH reporter expression, consistent with a loss-of-function, and a likely dominant-negative action of the mutant PRLR. Thus, our studies have identified that a loss-of-function PRLR germline mutation that results in prolactin insensitivity is a cause of familial hyperprolactinaemia.
Volume 34
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Endocrine Abstracts
ISSN 1470-3947 (print) | ISSN 1479-6848 (online)
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