scholarly journals Identification of Molecular Phenotypes and Biased Signaling Induced by Naturally Occurring Mutations of the Human Calcium-Sensing Receptor

Endocrinology ◽  
2012 ◽  
Vol 153 (9) ◽  
pp. 4304-4316 ◽  
Author(s):  
Katie Leach ◽  
Adriel Wen ◽  
Anna E. Davey ◽  
Patrick M. Sexton ◽  
Arthur D Conigrave ◽  
...  

More than 200 naturally occurring mutations have been identified in the human CaSR, which have been linked to diseases involving dysregulation of extracellular Ca2+ homeostasis. These mutations have classically been termed “loss-” or “gain-of-function” mutations, which is an oversimplification given that amino acid changes can alter numerous molecular properties of a receptor. We thus sought to characterize the effects of 21 clinically relevant mutations, the majority located in the heptahelical domains and extracellular loop regions of the CaSR, using flow cytometry to measure cell surface receptor expression levels, and measurements of intracellular Ca2+ mobilization and ERK1/2 phosphorylation to monitor receptor signaling. We identified distinct molecular phenotypes caused by these naturally occurring amino acid substitutions, which included combinations of loss- and gain-of-expression and changes in intrinsic signaling capacity. Importantly, we also identified biased signaling in the response of the CaSR to different mutations across the two pathways, indicating that some mutations resulted in receptor conformations that differentially altered receptor-coupling preferences. These findings have important implications for understanding the causes of diseases linked to the CaSR. A full appreciation of the molecular effects of these amino acid changes may enable the development of therapeutics that specifically target the molecular determinant of impairment in the receptor.

2019 ◽  
Vol 2019 (4) ◽  
Author(s):  
Anthony P. Davenport ◽  
Birgitte Holst ◽  
Matthias Kleinz ◽  
Janet J. Maguire ◽  
Bjørn B. Sivertsen

The ghrelin receptor (nomenclature as agreed by the NC-IUPHAR Subcommittee for the Ghrelin receptor [18]) is activated by a 28 amino-acid peptide originally isolated from rat stomach, where it is cleaved from a 117 amino-acid precursor (GHRL, Q9UBU3). The human gene encoding the precursor peptide has 83% sequence homology to rat prepro-ghrelin, although the mature peptides from rat and human differ by only two amino acids [70]. Alternative splicing results in the formation of a second peptide, [des-Gln14]ghrelin with equipotent biological activity [48]. A unique post-translational modification (octanoylation of Ser3, catalysed by ghrelin Ο-acyltransferase (MBOAT4, Q96T53) [127] occurs in both peptides, essential for full activity in binding to ghrelin receptors in the hypothalamus and pituitary, and for the release of growth hormone from the pituitary [56]. Structure activity studies showed the first five N-terminal amino acids to be the minimum required for binding [4], and receptor mutagenesis has indicated overlap of the ghrelin binding site with those for small molecule agonists and allosteric modulators of ghrelin function [43]. In cell systems, the ghrelin receptor is constitutively active [44], but this is abolished by a naturally occurring mutation (A204E) that results in decreased cell surface receptor expression and is associated with familial short stature [88].


2018 ◽  
Vol 19 (10) ◽  
pp. 2912 ◽  
Author(s):  
Girdhari Rijal ◽  
Jing Wang ◽  
Ilhan Yu ◽  
David Gang ◽  
Roland Chen ◽  
...  

Porcine mammary fatty tissues represent an abundant source of natural biomaterial for generation of breast-specific extracellular matrix (ECM). Here we report the extraction of total ECM proteins from pig breast fatty tissues, the fabrication of hydrogel and porous scaffolds from the extracted ECM proteins, the structural properties of the scaffolds (tissue matrix scaffold, TMS), and the applications of the hydrogel in human mammary epithelial cell spatial cultures for cell surface receptor expression, metabolomics characterization, acini formation, proliferation, migration between different scaffolding compartments, and in vivo tumor formation. This model system provides an additional option for studying human breast diseases such as breast cancer.


Immunology ◽  
2018 ◽  
Vol 156 (2) ◽  
pp. 136-146 ◽  
Author(s):  
Diana M. Elizondo ◽  
Temesgen E. Andargie ◽  
Naomi L. Haddock ◽  
Thomas A. Boddie ◽  
Michael W. Lipscomb

Blood ◽  
1986 ◽  
Vol 67 (6) ◽  
pp. 1631-1638 ◽  
Author(s):  
KM Shannon ◽  
JW Larrick ◽  
SA Fulcher ◽  
KB Burck ◽  
J Pacely ◽  
...  

Abstract The relative requirements of colonies derived from erythroid (BFU-E) and myeloid (CFU-c) progenitors for transferrin were examined using monoclonal antibodies directed against the transferrin molecule (TF-6) or its cell surface receptor (TFR-A12, TFR1–2B). Growth of erythroid bursts was profoundly reduced at concentrations of all three antibodies that had no effect on CFU-c-derived colonies. When TFR1–2B was layered over cultures established one to seven days previously, further burst development was inhibited, and degeneration of early erythroid colonies was observed. Addition of erythropoietin augmented transferrin receptor expression on cells harvested after 1 to 2 weeks in culture and analyzed by flow cytometry. Recombinant human erythropoietin gave results comparable to those obtained in experiments using human urinary erythropoietin. Analysis of erythroblasts plucked directly from culture plates confirmed the presence of transferrin receptors on BFU-E-derived colonies. Thymidine incorporation was maximal early in the second week of culture and coincided with high transferrin receptor expression. These data demonstrate that transferrin must be available into the second week of culture to support the growth and differentiation of BFU- E-derived erythroid bursts, that the generation of erythroid colonies from BFU-E is more dependent on transferrin than myeloid colony formation from CFU-c, and that erythropoietin modulates the expression of transferrin receptors on growing bursts.


Nature ◽  
1991 ◽  
Vol 352 (6337) ◽  
pp. 729-731 ◽  
Author(s):  
Hao Wang ◽  
Michael P. Kavanaugh ◽  
R. Alan North ◽  
David Kabat

2000 ◽  
Vol 48 (10) ◽  
pp. 569-578 ◽  
Author(s):  
Marina Y. Pushkareva ◽  
Sharon L. Wannberg ◽  
Andrew S. Janoff ◽  
Eric Mayhew

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