Fluoride induces endoplasmic reticulum stress in ameloblasts responsible for dental enamel formation

Kaori Kubota, Daniel H. Lee, Masahiro Tsuchiya, Conan S. Young, Eric T. Everett, Esperanza Martinez Mier, Malcolm L. Snead, Linh Nguyen, Fumihiko Urano, John D. Bartlett

Research output: Contribution to journalArticle

120 Citations (Scopus)

Abstract

The mechanism of how fluoride causes fluorosis remains unknown. Exposure to fluoride can inhibit protein synthesis, and this may also occur by agents that cause endoplasmic reticulum (ER) stress. When translated proteins fail to fold properly or become misfolded, ER stress response genes are induced that together comprise the unfolded protein response. Because ameloblasts are responsible for dental enamel formation, we used an ameloblast-derived cell line (LS8) to characterize specific responses to fluoride treatment. LS8 cells were growth-inhibited by as little as 1.9-3.8 ppm fluoride, whereas higher doses induced ER stress and caspase-mediated DNA fragmentation. Growth arrest and DNA damage-inducible proteins (GADD153/CHOP, GADD45α), binding protein (BiP/glucose-responsive protein 78 (GRP78), the non-secreted form of carbonic anhydrase VI (CA-VI), and active X-box-binding protein-1 (Xbp-1) were all induced significantly after exposure to 38 ppm fluoride. Unexpectedly, DNA fragmentation increased when GADD153 expression was inhibited by short interfering RNA treatment but remained unaffected by transient GADD153 overexpression. Analysis of control and GADD153-/- embryonic fibroblasts demonstrated that caspase-3 mediated the increased DNA fragmentation observed in the GADD153 null cells. We also demonstrate that mouse incisor ameloblasts are sensitive to the toxic effects of high dose fluoride in drinking water. Activated Ire1 initiates an ER stress response pathway, and mouse ameloblasts were shown to express activated Ire1. Ire1 levels appeared induced by fluoride treatment, indicating that ER stress may play a role in dental fluorosis. Low dose fluoride, such as that present in fluoridated drinking water, did not induce ER stress.

Original languageEnglish (US)
Pages (from-to)23194-23202
Number of pages9
JournalJournal of Biological Chemistry
Volume280
Issue number24
DOIs
StatePublished - Jun 17 2005

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Ameloblasts
Endoplasmic Reticulum Stress
Enamels
Dental Enamel
Fluorides
DNA Fragmentation
DNA
Drinking Water
Carrier Proteins
Proteins
Transcription Factor CHOP
Dental Fluorosis
Unfolded Protein Response
Null Lymphocytes
Poisons
Cell growth
Incisor
Fibroblasts
Growth
Caspases

ASJC Scopus subject areas

  • Biochemistry

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Fluoride induces endoplasmic reticulum stress in ameloblasts responsible for dental enamel formation. / Kubota, Kaori; Lee, Daniel H.; Tsuchiya, Masahiro; Young, Conan S.; Everett, Eric T.; Martinez Mier, Esperanza; Snead, Malcolm L.; Nguyen, Linh; Urano, Fumihiko; Bartlett, John D.

In: Journal of Biological Chemistry, Vol. 280, No. 24, 17.06.2005, p. 23194-23202.

Research output: Contribution to journalArticle

Kubota, K, Lee, DH, Tsuchiya, M, Young, CS, Everett, ET, Martinez Mier, E, Snead, ML, Nguyen, L, Urano, F & Bartlett, JD 2005, 'Fluoride induces endoplasmic reticulum stress in ameloblasts responsible for dental enamel formation', Journal of Biological Chemistry, vol. 280, no. 24, pp. 23194-23202. https://doi.org/10.1074/jbc.M503288200
Kubota, Kaori ; Lee, Daniel H. ; Tsuchiya, Masahiro ; Young, Conan S. ; Everett, Eric T. ; Martinez Mier, Esperanza ; Snead, Malcolm L. ; Nguyen, Linh ; Urano, Fumihiko ; Bartlett, John D. / Fluoride induces endoplasmic reticulum stress in ameloblasts responsible for dental enamel formation. In: Journal of Biological Chemistry. 2005 ; Vol. 280, No. 24. pp. 23194-23202.
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AU - Martinez Mier, Esperanza

AU - Snead, Malcolm L.

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AU - Urano, Fumihiko

AU - Bartlett, John D.

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