Ca2+ transport and signalling in enamel cells. (13th October 2016)

• Record Type: Journal Article
• Authors: Nurbaeva, Meerim K.; Eckstein, Miriam; Feske, Stefan; Lacruz, Rodrigo S.
• Is Part Of: Journal of physiology. Volume 595:Number 10(2017)
• Page Start: 3015
• Page End: 3039
• Publication Date: 2016-10-13
• Subjects: calcium -- calcium channel -- calcium regulation -- calcium signalling -- calcium transport; Physiology -- Periodicals; 612.005
• DOI: 10.1113/JP272775
• Languages: English
• ISSNs: 0022-3751

Abstract

Abstract : Generalized model for Ca 2+ transport in dental enamel cells (ameloblasts). Ca 2+ is transported across a semipermeable cell barrier to reach the growing enamel crystals. Recently, store‐operated Ca 2+ entry has been implicated as a key Ca 2+ influx system, with inositol receptors probably involved in Ca 2+ release. SERCA2 is the most prominent refilling pump of the endoplasmic reticulum lumen. Extrusion involves the exchangers NCKX4 and two NCXs. Plasma membrane Ca 2+ ‐ATPases (PMCAs) are also involved. The full cellular machinery used by ameloblasts to modulate Ca 2+ transport and signalling is discussed. Abstract: Dental enamel is one of the most remarkable examples of matrix‐mediated biomineralization. Enamel crystals form de novo in a rich extracellular environment in a stage‐dependent manner producing complex microstructural patterns that are visually stunning. This process is orchestrated by specialized epithelial cells known as ameloblasts which themselves undergo striking morphological changes, switching function from a secretory role to a cell primarily engaged in ionic transport. Ameloblasts are supported by a host of cell types which combined represent the enamel organ. Fully mineralized enamel is the hardest tissue found in vertebrates owing its properties partly to the unique mixture of ionic species represented and their highly organized assembly in the crystal lattice. Among the main elements found in enamel, Ca 2+ is the most abundant ion, yet how ameloblasts modulate Ca 2+ dynamics remains poorly known. This review describes previously proposed models for passive and active Ca 2+ transport, the intracellular Ca 2+ buffering systems expressed in ameloblasts and provides an up‐dated view of current models concerning Ca 2+ influx and extrusion mechanisms, where most of the recent advances have been made. We also advance a new model for Ca 2+ transport by the enamel organ.