Mutation of plasma membrane Ca2+ ATPase isoform 3 in a family with X-linked congenital cerebellar ataxia impairs Ca2+ homeostasis.
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.
Unit of Molecular Medicine for Neuromuscular and Neurodegenerative Disorders, Department of Neurosciences, Bambino Gesù Children's Hospital, Istituti di Ricovero e Cura a Carattere Scientifico, 00165 Rome, Italy.
Ginevra
G
Zanni
Tito
T
Calì
Vera M
VM
Kalscheuer
Denis
D
Ottolini
Sabina
S
Barresi
Nicolas
N
Lebrun
Luisa
L
Montecchi-Palazzi
Hao
H
Hu
Jamel
J
Chelly
Enrico
E
Bertini
Marisa
M
Brini
Ernesto
E
Carafoli
D000331:Aequorin; D000595:Amino Acid Sequence; D001483:Base Sequence; D015153:Blotting, Western; D002118:Calcium / Q000378:metabolism*; D002524:Cerebellar Ataxia / Q000235:genetics*; D017931:DNA Primers / Q000235:genetics; D040181:Genetic Diseases, X-Linked / Q000235:genetics*; D006367:HeLa Cells; D006706:Homeostasis / Q000235:genetics*; D006801:Humans; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009154:Mutation / Q000235:genetics; D009474:Neurons / Q000378:metabolism*; D010375:Pedigree; D053499:Plasma Membrane Calcium-Transporting ATPases / Q000737:chemistry / Q000235:genetics*; D020033:Protein Isoforms / Q000235:genetics; D017422:Sequence Analysis, DNA
D017931:DNA Primers; D020033:Protein Isoforms; D000331:Aequorin; D053499:Plasma Membrane Calcium-Transporting ATPases; D002118:Calcium