PMCA Ca2+ clearance in dental enamel cells depends on the magnitude of cytosolic Ca2+

Guilherme Henrique Souza Bomfim, Marta Giacomello, Rodrigo S. Lacruz

Research output: Contribution to journalArticlepeer-review

Abstract

Enamel formation (amelogenesis) is a two-step process whereby crystals partially grow during the secretory stage followed by a significant growth expansion during the maturation stage concurrent with an increase in vectorial Ca2+ transport. This requires tight regulation of cytosolic Ca2+ (cCa2+) concentration in the enamel forming ameloblasts by controlling Ca2+ influx (entry) and Ca2+ extrusion (clearance). Gene and protein expression studies suggest that the plasma membrane Ca2+-ATPases (PMCA1-4) are likely involved in cCa2+ extrusion in ameloblasts, yet no functional analysis of these pumps has been reported nor whether their activity changes across amelogenesis. PMCAs have high Ca2+ affinity and low Ca2+ clearance which may be a limiting factor in their contribution to enamel formation as maturation stage ameloblasts handle high Ca2+ loads. We analyzed PMCA function in rat secretory and maturation ameloblasts by blocking or potentiating these pumps. Low/moderate elevations in cCa2+ measured using the Ca2+ probe Fura-2-AM show that secretory ameloblasts clear Ca2+ faster than maturation stage cells through PMCAs. This process was completely inhibited by an external alkaline (pH 9.0) solution or was significantly delayed by the PMCA blockers vanadate and caloxin 1b1. Eliciting higher cCa2+ transients via the activation of the ORAI1 Ca2+ channel showed that the PMCAs of maturation ameloblasts were more efficient. Inhibiting PMCAs decreased the rate of Ca2+ influx via ORAI1 but potentiation with forskolin had no effect. Our findings suggest that PMCAs are functional Ca2+ pumps during amelogenesis regulating cCa2+ upon low and/or moderate Ca2+ stimulus in secretory stage, thus participating in amelogenesis.

Original languageEnglish (US)
Article numbere22679
JournalFASEB Journal
Volume37
Issue number1
DOIs
StatePublished - Jan 2023

Keywords

  • ameloblasts
  • Ca clearance
  • Ca signaling
  • enamel cells
  • PMCA

ASJC Scopus subject areas

  • Biotechnology
  • Biochemistry
  • Molecular Biology
  • Genetics

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