Autosomal dominant hypocalcemia caused by a novel mutation in the loop 2 region of the human calcium receptor extracellular domain

Jianxin Hu, Stefano Mora, Giacomo Colussi, Maria Carla Proverbio, Kendra A. Jones, Laura Bolzoni, Maria E. De Ferrari, Giovanni Civati, Allen M. Spiegel

Research output: Contribution to journalArticle

22 Citations (Scopus)

Abstract

We report a novel missense mutation N124K in the extracellular calcium receptor (CaR) identified in two related subjects with the phenotypic features of autosomal dominant hypocalcemia (ADH). Expression of the N124K mutant receptor created by site-directed mutagenesis and transfected into HEK-293 cells was comparable with that of the wild-type (WT) receptor and two other mutant receptors N118K and L125P identified in subjects with ADH. Functional characterization by the extracellular Ca2+ ion ([Ca2+]0)-stimulated phosphoinositide (PI) hydrolysis in transfected HEK-293 cells showed that the N124K mutant receptor was left-shifted in Ca2+ sensitivity. This biochemical gain-of-function is comparable with that seen in other missense mutations of the CaR identified in subjects with ADH. We tested a series of missense substitutions (R, Q, E, and G) in addition to K for N124 and found that only the N124K mutation and to a much lesser extent N124R caused a left shift in Ca2+ sensitivity. Thus, a specific substitution, not merely a mutation of the N124 residue, is required for receptor activation. The N124K mutation is one of eight naturally occurring mutations in subjects with ADH identified in a short segment A116-C129 of the CaR extracellular domain (ECD). We present a hypothesis to explain receptor activation by mutations in this region based on the recently described three-dimensional structure of the related metabotropic glutamate type 1 receptor (mGluR1).

Original languageEnglish (US)
Pages (from-to)1461-1469
Number of pages9
JournalJournal of Bone and Mineral Research
Volume17
Issue number8
StatePublished - 2002
Externally publishedYes

Fingerprint

Calcium-Sensing Receptors
Mutation
HEK293 Cells
Missense Mutation
Phosphatidylinositols
Site-Directed Mutagenesis
Hydrolysis
Familial Hypercalciuric Hypocalcemia
Ions

Keywords

  • Autosomal dominant hypocalcemia
  • Extracellular domain
  • Human calcium receptor
  • Hypoparathyroidism
  • Mutation

ASJC Scopus subject areas

  • Surgery

Cite this

Autosomal dominant hypocalcemia caused by a novel mutation in the loop 2 region of the human calcium receptor extracellular domain. / Hu, Jianxin; Mora, Stefano; Colussi, Giacomo; Proverbio, Maria Carla; Jones, Kendra A.; Bolzoni, Laura; De Ferrari, Maria E.; Civati, Giovanni; Spiegel, Allen M.

In: Journal of Bone and Mineral Research, Vol. 17, No. 8, 2002, p. 1461-1469.

Research output: Contribution to journalArticle

Hu, J, Mora, S, Colussi, G, Proverbio, MC, Jones, KA, Bolzoni, L, De Ferrari, ME, Civati, G & Spiegel, AM 2002, 'Autosomal dominant hypocalcemia caused by a novel mutation in the loop 2 region of the human calcium receptor extracellular domain', Journal of Bone and Mineral Research, vol. 17, no. 8, pp. 1461-1469.
Hu, Jianxin ; Mora, Stefano ; Colussi, Giacomo ; Proverbio, Maria Carla ; Jones, Kendra A. ; Bolzoni, Laura ; De Ferrari, Maria E. ; Civati, Giovanni ; Spiegel, Allen M. / Autosomal dominant hypocalcemia caused by a novel mutation in the loop 2 region of the human calcium receptor extracellular domain. In: Journal of Bone and Mineral Research. 2002 ; Vol. 17, No. 8. pp. 1461-1469.
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