Developmental expression of SLC26A4 (Pendrin) during amelogenesis in developing rodent teeth

• Published in: European journal of oral sciences 2011-12, Vol.119 (Suppl 1), p.185-192
• Main Authors: Bronckers, Antonius LJJ, Guo, Jing, Zandieh-Doulabi, Behrouz, Bervoets, Theodore J, Lyaruu, Donacian M., Li, Xiangming, Wangemann, Philine, DenBesten, Pamela
• Format: Article
• Language: English
• ISSN: 0909-8836; 1600-0722
• DOI: 10.1111/j.1600-0722.2011.00901.x

Ameloblasts need to regulate pH during formation of enamel crystals, a process that generates protons. Solute carrier family 26A member 4 (SLC26A4, or pendrin) is an anion exchanger for chloride, bicarbonate, iodine and formate. It is expressed in apical membranes of ion-transporting epithelia in kidney, inner ear and thyroid where it regulates luminal pH and fluid transport. We hypothesized that maturation ameloblasts express SLC26A4 to neutralize acidification of enamel fluid in forming enamel. In rodents, secretory and maturation ameloblasts were immunopositive for SLC26A4. Staining was particularly strong in apical membranes of maturation ameloblasts facing forming enamel. RT-PCR confirmed the presence of mRNA transcripts for Slc26a4 in enamel organs. SLC26A4 immunostaining was also found in mineralizing connective tissues including odontoblasts, osteoblasts, osteocytes, osteoclasts, bone lining cells, cellular cementoblasts and cementocytes. However, Slc26a4- null mutant mice had no overt dental phenotype. The presence of SLC26A4 in apical plasma membranes of maturation ameloblasts is consistent with a potential function as pH regulator. SLC26A4 does not appear critical for ameloblast functioning and is likely compensated by other pH regulators.