Mechanism of toxic action of fluoride in dental fluorosis: whether trimeric G proteins participate in the disturbance of intracellular transport of secretory ameloblast exposed to fluoride |
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Authors: | Saburou Matsuo Ken-ichi Kiyomiya Masaru Kurebe |
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Institution: | (1) Department of Toxicology, School of Veterinary Medicine, Osaka Prefecture University, 1-1 Gakuen-cho, Sakai, Osaka 599-8531, Japan Fax: +81-722-54-9918; Tel.:+81-722-54-9894 e-mail: matsuos@jyui.vet.osakafu-u.ac.jp, JP |
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Abstract: | In enamel fluorosis model rats treated with sodium fluoride, secretory ameloblasts of incisor tooth germs exhibited disruption
of intracellular trafficking. We examined whether heterotrimeric G proteins participated in the disruption of vesicular trafficking
of the secretory ameloblast exposed to fluoride, using immunoblotting and pertussis toxin (IAP)-induced adenosyl diphosphate
(ADP)-ribosylation for membrane fractions of the cell. Immunoblotting of crude membranes, post supernatants of the ameloblast,
with anti-Gi3/o and anti-Gs antibodies showed that Gi3 or Go proteins existed in the secretory ameloblast, but Gs protein did not. Immunoblotting of the subcellular membrane fractions indicated that the Gi3 or Go proteins were located in the Golgi membrane, but were not in the rough endoplasmic reticulum (rER) membrane. Autoradiograph
of IAP-induced ADP-ribosylation, however, showed the existence of IAP-sensitive G proteins both in rER and Golgi membranes.
Fluoride treatment decreased the G proteins bound to both membranes. These findings indicate that different G proteins, both
of which are IAP-sensitive, are present in the rER and Golgi apparatus, and suggest that these G proteins participate in the
disturbance of intracellular transport of the secretory ameloblast exposed to fluoride.
Received: 24 June 1998 / Accepted: 8 September 1998 |
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Keywords: | Heterotrimeric G protein Vesicle trafficking Fluoride Ameloblast Mottled enamel |
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