G120R, a Human Growth Hormone Antagonist, Shows Zinc-dependent Agonist and Antagonist Activity on Nb2 Cells

Dattani, Mehul; Hindmarsh, Peter C.; Brook, C. G. D.; Robinson, Iain C. A. F.; Kopchick, John J.; Marshall, Nicholas J.

doi:10.1074/jbc.270.16.9222

Cited by 47 publications

(30 citation statements)

References 19 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Further, G120R has been shown to act as an antagonist on human PRLR (32) and also to cause rodent PRLR-mediated proliferation of Nb-2 cells in the presence of Zn 2ϩ (10 M) (33). Zn 2ϩ as a prerequisite for proliferation could possibly be explained with metal ion restoration of the ternary complex of hGH⅐PRLR.…”

Section: Discussionmentioning

confidence: 99%

Crystal Structure of an Antagonist Mutant of Human Growth Hormone, G120R, in Complex with Its Receptor at 2.9 Å Resolution

Sundström¹,

Lundqvist²,

Rödin³

et al. 1996

Journal of Biological Chemistry

View full text Add to dashboard Cite

Human growth hormone binds two receptor molecules and thereby induces signal transduction through receptor dimerization. At high concentrations, growth hormone acts as an antagonist because of a large difference in affinities at the respective binding sites. This antagonist action can be enhanced further by reducing binding in the low affinity binding site. A growth hormone antagonist mutant Gly-120 3 Arg, has been crystallized with its receptor as a 1:1 complex and the crystal structure determined at 2.9 Å resolution. The 1:1 complex is remarkably similar to the native growth hormone-receptor 1:2 complex. A comparison between the two structures reveals only minimal differences in the conformations of the hormone or its receptor in the two complexes, including the angle between the two immunoglobulin-like domains of the receptor. Further, two symmetry-related 1:1 complexes in the crystal form a 2:2 complex with a large solvent inaccessible area between two receptor molecules. In addition, we present here a native human growth hormone-human growth hormone-binding protein 1:2 complex structure at 2.5 Å resolution. One important difference between our structure and the previously published crystal structure at 2.8 Å is revealed. Trp-104 in the receptor, a key residue in the hormone-receptor interaction, has an altered conformation in the low affinity site enabling a favorable hydrogen bond to be formed with Asp-116 of the hormone.

show abstract

Section: Discussionmentioning

confidence: 99%

Crystal Structure of an Antagonist Mutant of Human Growth Hormone, G120R, in Complex with Its Receptor at 2.9 Å Resolution

Sundström¹,

Lundqvist²,

Rödin³

et al. 1996

Journal of Biological Chemistry

View full text Add to dashboard Cite

show abstract

“…As described above, the GHR antagonist, PEGV, competitively blocks the GHRs in all peripheral tissues (45)(46)(47). Thus, the higher the endogenous GH level, the more PEGV is needed to effectively block GH actions (4).…”

Section: How Ghr Antagonists Workmentioning

confidence: 99%

Hypothesis: Extra-hepatic acromegaly: a new paradigm?

Neggers

Kopchick

Jørgensen

et al. 2011

European Journal of Endocrinology

View full text Add to dashboard Cite

Medical treatment of acromegaly with long-acting somatostatin analogs (LA-SMSA) and the GH receptor antagonist, pegvisomant (PEGV), has made it possible to achieve normal serum IGF1 concentrations in a majority of patients with acromegaly. These two compounds, however, impact the GH-IGF1 axis differently, which challenges the traditional biochemical assessment of the therapeutic response. We postulate that LA-SMSA in certain patients normalizes serum IGF1 levels in the presence of elevated GH actions in extra-hepatic tissues. This may result in persistent disease activity for which we propose the term extra-hepatic acromegaly. PEGV, on the other hand, blocks systemic GH actions, which are not necessarily reliably reflected by serum IGF1 levels, and this treatment causes a further elevation of serum GH levels. Medical treatment is therefore difficult to monitor with the traditional biomarkers. Moreover, the different modes of actions of LA-SMSA and PEGV make it attractive to use the two drugs in combination. We believe that it is time to challenge the existing concepts of treatment and monitoring of patients with acromegaly.

show abstract

“…For example, although G129R-hPRL (25)(26)(27) and G120R-hGH (or G120K-hGH) (24,39,48) have been characterized as potent antagonists toward the PRLR in various cell-based assays, both are weak agonists and fail to antagonize WT lactogens in the Nb2 cell proliferation assay (31,39,44). This can be explained by the fact that maximal Nb2 cell proliferation is achieved at very low receptor occupancy (49), as highlighted by immunoblot analyses where maximal activation of signal transducers (e.g.…”

Section: Fig 6 Cell Cycle Analyses On Human Mammary Tumor Epitheliamentioning

confidence: 99%

S179D-Human PRL, a Pseudophosphorylated Human PRL Analog, Is an Agonist and Not an Antagonist

et al. 2001

View full text Add to dashboard Cite

For many years, our group has been involved in the development of human PRL antagonists. In two recent publications, S179D-human PRL, a human PRL analog designed to mimic a putative S179-phosphorylated human PRL, was reported to be a highly potent antagonist of human PRL-induced proliferation and signaling in rat Nb2 cells. We prepared this analog with the aim of testing it in various bioassays involving the homologous, human PRL receptor. In our hands, S179D-human PRL was able to stimulate 1) the proliferation of rat Nb2 cells and of human mammary tumor epithelial cells (T-47D), 2) transcriptional activation of the lactogenic hormone response element-luciferase reporter gene, and 3) activation of the Janus kinase/signal transducer and activator of transcription and MAPK pathways. Using the previously characterized antagonist G129R-human PRL as a control, we failed to observe any evidence for antagonism of S179D-human PRL toward any of the human PRL-induced effects analyzed, including cell proliferation, transcriptional activation, and signaling. In conclusion, our data argue that S179D-human PRL is an agonist displaying slightly reduced affinity and activity due to local alteration of receptor binding site 1, and that the antagonistic properties previously attributed to S179D-human PRL cannot be confirmed in any of the assays analyzed in this study. (Endocrinology 142: 3950 -3963, 2001)

show abstract

G120R, a Human Growth Hormone Antagonist, Shows Zinc-dependent Agonist and Antagonist Activity on Nb2 Cells

Cited by 47 publications

References 19 publications

Crystal Structure of an Antagonist Mutant of Human Growth Hormone, G120R, in Complex with Its Receptor at 2.9 Å Resolution

Crystal Structure of an Antagonist Mutant of Human Growth Hormone, G120R, in Complex with Its Receptor at 2.9 Å Resolution

Hypothesis: Extra-hepatic acromegaly: a new paradigm?

S179D-Human PRL, a Pseudophosphorylated Human PRL Analog, Is an Agonist and Not an Antagonist

Contact Info

Product

Resources

About