Mutation of plasma membrane Ca2+ ATPase isoform 3 in a family with X-linked congenital cerebellar ataxia impairs Ca2+ homeostasis

Proc Natl Acad Sci U S A. 2012 Sep 4;109(36):14514-9. doi: 10.1073/pnas.1207488109. Epub 2012 Aug 21.

Abstract

Ca(2+) in neurons is vital to processes such as neurotransmission, neurotoxicity, synaptic development, and gene expression. Disruption of Ca(2+) homeostasis occurs in brain aging and in neurodegenerative disorders. Membrane transporters, among them the calmodulin (CaM)-activated plasma membrane Ca(2+) ATPases (PMCAs) that extrude Ca(2+) from the cell, play a key role in neuronal Ca(2+) homeostasis. Using X-exome sequencing we have identified a missense mutation (G1107D) in the CaM-binding domain of isoform 3 of the PMCAs in a family with X-linked congenital cerebellar ataxia. PMCA3 is highly expressed in the cerebellum, particularly in the presynaptic terminals of parallel fibers-Purkinje neurons. To study the effects of the mutation on Ca(2+) extrusion by the pump, model cells (HeLa) were cotransfected with expression plasmids encoding its mutant or wild-type (wt) variants and with the Ca(2+)-sensing probe aequorin. The mutation reduced the ability of the PMCA3 pump to control the cellular homeostasis of Ca(2+). It significantly slowed the return to baseline of the Ca(2+) transient induced by an inositol-trisphosphate (InsP(3))-linked plasma membrane agonist. It also compromised the ability of the pump to oppose the influx of Ca(2+) through the plasma membrane capacitative channels.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Aequorin
  • Amino Acid Sequence
  • Base Sequence
  • Blotting, Western
  • Calcium / metabolism*
  • Cerebellar Ataxia / genetics*
  • DNA Primers / genetics
  • Genetic Diseases, X-Linked / genetics*
  • HeLa Cells
  • Homeostasis / genetics*
  • Humans
  • Models, Molecular*
  • Molecular Sequence Data
  • Mutagenesis, Site-Directed
  • Mutation / genetics
  • Neurons / metabolism*
  • Pedigree
  • Plasma Membrane Calcium-Transporting ATPases / chemistry
  • Plasma Membrane Calcium-Transporting ATPases / genetics*
  • Protein Isoforms / genetics
  • Sequence Analysis, DNA

Substances

  • DNA Primers
  • Protein Isoforms
  • Aequorin
  • Plasma Membrane Calcium-Transporting ATPases
  • Calcium