PMCA4 (ATP2B4) mutation in familial spastic paraplegia causes delay in intracellular calcium extrusion

Philip Wing Lok Ho, Shirley Yin Yu Pang, Miaoxin Li, Zero Ho Man Tse, Michelle Hiu Wai Kung, Pak Chung Sham, Shu Leong Ho

Research output: Journal article publicationJournal articleAcademic researchpeer-review

27 Citations (Scopus)

Abstract

Background: Familial spastic paraplegia (FSP) is a heterogeneous group of disorders characterized primarily by progressive lower limb spasticity and weakness. More than 50 disease loci have been described with different modes of inheritance. Recently, we described a novel missense mutation (c.803G>A, p.R268Q) in the plasma membrane calcium ATPase (PMCA4, or ATP2B4) gene in a Chinese family with autosomal dominant FSP. Further to this finding, here we describe the functional effect of this mutation. Methods: As PMCA4 removes cytosolic calcium, we measured transient changes and the time-dependent decay of cytosolic calcium level as visualized by using fura-2 fluorescent dye with confocal microscopy in human SH-SY5Y neuroblastoma cells overexpressing either wild-type or R268Q mutant PMCA4. Results: Overexpressing both wild-type and R268Q PMCA4 significantly reduced maximum calcium surge after KCl-induced depolarization as compared with vector control cells. However, cells overexpressing mutant PMCA4 protein demonstrated significantly higher level of calcium surge when compared with wild-type. Furthermore, the steady-state cytosolic calcium concentration in these mutant cells remained markedly higher than the wild-type after SERCA inhibition by thapsigargin. Conclusion: Our result showed that p.R268Q mutation in PMCA4 resulted in functional changes in calcium homeostasis in human neuronal cells. This suggests that calcium dysregulation may be associated with the pathogenesis of FSP.

Original languageEnglish
Pages (from-to)1-6
Number of pages6
JournalBrain and Behavior
Volume5
Issue number4
DOIs
Publication statusPublished - 1 Apr 2015
Externally publishedYes

Keywords

  • PMCA
  • ATP2B4
  • Calcium transient
  • Familial spastic paraplegia
  • Neurodegeneration

ASJC Scopus subject areas

  • Behavioral Neuroscience

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