The Growth Hormone Receptor (GHR) c.899dupC mutation functions as a dominant negative: Insights into the pathophysiology of intracellular GHR defects

Michael A. Derr, Javier Aisenberg, Peng Fang, Yardena Tenenbaum-Rakover, Ron G. Rosenfeld, Vivian Hwa

Research output: Contribution to journalArticle

19 Scopus citations

Abstract

Context: GH insensitivity (GHI) is a condition characterized by pronounced IGF-I deficiency and severe short stature. We previously identified a novel compound heterozygous GH receptor (GHR) mutation, GHR:p.R229H/c.899dupC, in a patient presenting with GHI. The heterozygous p.R229H (prepeptide) variant was previously associated with GHI despite a lack of adequate functional studies. The novel heterozygous GHR:c.899dupC variant affects the critical JAK2-binding Box 1 region of the GHR intracellular domain; the duplication predicted a frameshift and early protein termination. Objective: The individual and synergistic effect(s) of the p.R229H and c.899dupC mutations onGHR function(s) were evaluated in reconstitution studies. Results: The recombinant human GHR (hGHR):p.R229H variant was readily expressed, and unexpectedly, GH-induced signal transducerandactivator of transcription5b(STAT5b) phosphorylation was comparable to that induced by wild-type hGHR. The truncated, immunodetected hGHR: c.899dupC variant, in contrast, was unresponsive to GH. To mimic a compound heterozygous state, the two variants were coexpressed, and strikingly, the presence of the hGHR:c.899dupC effectively abolished the GH-induced STAT5b activities that were observed with hGHR:p.R229H alone. Furthermore, hGHR:c.899dupC dose-dependently reduced the GH-induced STAT5b activities associated with hGHR:p.R229H. This dominant negative effect was also observed when hGHR:c.899dupC was coexpressed with wild-type hGHR. Conclusion: The p.R229H variant, contrary to an earlier report, appeared to function like wild-type GHR and, therefore, is unlikely to cause GHI. The c.899dupC variant is a novel dominant negative mutation that disrupted normal GHR signaling and is the cause for the GHI phenotype of the reported patient.

Original languageEnglish (US)
Pages (from-to)E1896-E1904
JournalJournal of Clinical Endocrinology and Metabolism
Volume96
Issue number11
DOIs
StatePublished - Nov 1 2011

ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Biochemistry
  • Endocrinology
  • Clinical Biochemistry
  • Biochemistry, medical

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