Compounded PHOSPHO1/ALPL deficiencies reduce dentin mineralization.

Journal of dental research (2013-05-23)
M D McKee, M C Yadav, B L Foster, M J Somerman, C Farquharson, J L Millán
ABSTRACT

Phosphatases are involved in bone and tooth mineralization, but their mechanisms of action are not completely understood. Tissue-nonspecific alkaline phosphatase (TNAP, ALPL) regulates inhibitory extracellular pyrophosphate through its pyrophosphatase activity to control mineral propagation in the matrix; mice without TNAP lack acellular cementum, and have mineralization defects in dentin, enamel, and bone. PHOSPHO1 is a phosphatase found within membrane-bounded matrix vesicles in mineralized tissues, and double ablation of Alpl and Phospho1 in mice leads to a complete absence of skeletal mineralization. Here, we describe mineralization abnormalities in the teeth of Phospho1(-/-) mice, and in compound knockout mice lacking Phospho1 and one allele of Alpl (Phospho1(-/-);Alpl(+/-) ). In wild-type mice, PHOSPHO1 and TNAP co-localized to odontoblasts at early stages of dentinogenesis, coincident with the early mineralization of mantle dentin. In Phospho1 knockout mice, radiography, micro-computed tomography, histology, and transmission electron microscopy all demonstrated mineralization abnormalities of incisor dentin, with the most remarkable findings being reduced overall mineralization coincident with decreased matrix vesicle mineralization in the Phospho1(-/-) mice, and the almost complete absence of matrix vesicles in the Phospho1(-/-);Alpl(+/-) mice, whose incisors showed a further reduction in mineralization. Results from this study support prominent non-redundant roles for both PHOSPHO1 and TNAP in dentin mineralization.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Phosphatase, Alkaline bovine, recombinant, expressed in Pichia pastoris, ≥4000 units/mg protein
Sigma-Aldrich
Phosphatase, Alkaline shrimp, ≥1,000 DEA units/mL, buffered aqueous glycerol solution, recombinant, expressed in proprietary host
Sigma-Aldrich
Phosphatase, Alkaline from Escherichia coli, lyophilized powder, 30-60 units/mg protein (in glycine buffer)
Sigma-Aldrich
Phosphatase, Alkaline from Escherichia coli, ammonium sulfate suspension, 30-90 units/mg protein (modified Warburg-Christian, in glycine buffer)
Sigma-Aldrich
Phosphatase, Alkaline from Escherichia coli, buffered aqueous glycerol solution, 20-50 units/mg protein (in glycine buffer)
Sigma-Aldrich
Phosphatase, Alkaline from porcine kidney, lyophilized powder, ≥100 DEA units/mg protein
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Phosphatase, Alkaline from bovine intestinal mucosa, buffered aqueous glycerol solution, ≥5,500 DEA units/mg protein
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Phosphatase, Alkaline from bovine intestinal mucosa, BioUltra, buffered aqueous glycerol solution, ≥6,000 DEA units/mg protein
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Phosphatase, Alkaline from calf intestine, buffered aqueous glycerol solution
Sigma-Aldrich
Phosphatase, Alkaline from bovine intestinal mucosa, buffered aqueous glycerol solution, ≥4,000 DEA units/mg protein
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Phosphatase, Alkaline from bovine intestinal mucosa, buffered aqueous solution, ≥2,000 DEA units/mg protein
Sigma-Aldrich
Phosphatase, Alkaline from bovine intestinal mucosa, lyophilized powder, ≥10 DEA units/mg solid
Sigma-Aldrich
Phosphatase, Alkaline from bovine kidney, lyophilized powder, ≥5 units/mg protein (Activity determined in diethanolamine buffer, pH 9.8)