Molecular interactions of EphA4, growth hormone receptor, Janus kinase 2, and signal transducer and activator of transcription 5B

GH receptor (GHR) and prolactin (PRL) receptor (PRLR) are structurally similar cytokine receptor superfamily members that are highly conserved among species. GH has growth-promoting and metabolic effects in various tissues in vertebrates, including humans. PRL is essential for regulation of lactation in mammals. Recent studies indicate that breast tissue bears GHR and PRLR and that both GH and PRL may impact development or behavior of breast cancer cells. An important facet of human GH (hGH) and human PRL (hPRL) biology is that although hPRL interacts only with hPRLR, hGH binds well to both hGHR and hPRLR. Presently, we investigated potential signaling effects of both hormones in the estrogen receptor- and progesterone receptor-positive human T47D breast cancer cell line. We found that this cell type expresses ample GHR and PRLR and responds well to both hGH and hPRL, as evidenced by activation of the Janus kinase 2/signal transducer and activator of transcription 5 pathway. Immunoprecipitation studies revealed specific GHR-PRLR association in these cells that was acutely enhanced by GH treatment. Although GH caused formation of disulfide-linked and chemically cross-linked GHR dimers in T47D cells, GH preferentially induced tyrosine phosphorylation of PRLR rather than GHR. Notably, both a GHR-specific ligand antagonist (B2036) and a GHR-specific antagonist monoclonal antibody (anti-GHRext-mAb) failed to inhibit GH-induced signal transducer and activator of transcription 5 activation. In contrast, although the non-GHR-specific GH antagonist (G120R) and the PRL antagonist (G129R) individually only partially inhibited GH-induced activation, combined treatment with these two antagonists conferred greater inhibition than either alone. These data indicate that endogenous GHR and PRLR associate (possibly as a GHR-PRLR heterodimer) in human breast cancer cells and that GH signaling in these cells is largely mediated by the PRLR in the context of both PRLR-PRLR homodimers and GHR-PRLR heterodimers, broadening our understanding of how these related hormones and their related receptors may function in physiology and pathophysiology.

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Growth Hormone Stimulates Hepatic Expression of Bovine Growth Hormone Receptor Messenger Ribonucleic Acid through Signal Transducer and Activator of Transcription 5 Activation of a Major Growth Hormone Receptor Gene Promoter

Endocrinology ◽

10.1210/en.2006-1738 ◽

2007 ◽

Vol 148 (7) ◽

pp. 3307-3315 ◽

Cited By ~ 20

Author(s):

Honglin Jiang ◽

Ying Wang ◽

Miaozong Wu ◽

Zhiliang Gu ◽

Stuart J. Frank ◽

...

Keyword(s):

Growth Hormone ◽

Binding Site ◽

Hormone Receptor ◽

Growth Hormone Receptor ◽

Bovine Liver ◽

Signal Transducer ◽

Sequence Element ◽

Hepatic Expression ◽

Mrna Variant ◽

Igf I

The objective of this study was to determine whether and how GH regulates hepatic expression of GH receptor (GHR) mRNA in cattle. Ribonuclease protection assays revealed that injection of GH in a slow-release formula increased both hepatic GHR and IGF-I mRNAs 1 wk after the injection. The increases in GHR and IGF-I mRNAs were highly correlated. Western blot analysis showed that the injection also increased liver GHR protein level. In cattle and other mammals, hepatic GHR mRNA is expressed as variants that differ in the 5′-untranslated region due to the use of different promoters in transcription and/or alternative splicing. We found that GH increased the expression of the liver-specific GHR mRNA variant GHR1A without affecting the other two major GHR mRNA variants in the bovine liver, GHR1B and GHR1C. In transient transfection analyses, GH could robustly activate reporter gene expression from a 2.7-kb GHR1A promoter, suggesting that GH augmentation of GHR1A mRNA expression in the liver is at least partially mediated at the transcriptional level. Additional transfection analyses of serially 5′-truncated fragments of this promoter narrowed the GH-responsive sequence element down to a 210-bp region that contained a putative signal transducer and activator of transcription 5 (STAT5) binding site. EMSAs demonstrated that this putative STAT5 binding site was able to bind to STAT5b protein. In cotransfection assays, deletion of this putative STAT5 binding site abolished most of the GH response of the GHR1A promoter. Like 1-wk GH action, 6-h (i.e. short-term) GH action also increased liver expression of GHR1A and total GHR mRNAs in cattle. These observations together suggest that GH directly stimulates the expression of one GHR mRNA variant, GHR1A, through binding STAT5 to its promoter, thereby increasing GHR mRNA and protein expression in the bovine liver.

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Laron syndrome – A case Report

JMS SKIMS ◽

10.33883/jms.v20i2.204 ◽

2017 ◽

Vol 20 (2) ◽

pp. 104-106

Author(s):

Javaid Ahmad Bhat ◽

Moomin Hussain Bhat ◽

Hilal Bhat ◽

Mona Sood ◽

Shariq Rashid Masoodi

Keyword(s):

Growth Hormone ◽

Case Report ◽

Hormone Receptor ◽

Growth Hormone Receptor ◽

Genetic Disorder ◽

Female Child ◽

Receptor Signaling ◽

Laron Syndrome ◽

Rare Genetic Disorder ◽

Igf I

Background : Laron & colleagues (1966) reported a rare genetic disorder in Israliei Jewish sublings which was characterized by insensitivity to growth hormone due to abnormality in growth hormone receptor or post receptor signaling pathway.Case Report: We hereby report a case of a 5 year old female child who presented to us with features similar to Laron syndrome. The diagnosis was made & confirmed by various Lab. investigations like low IGF-I levels and managed accordingly. JMS 2017; 20 (2):104-106

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