Correction of Hypophosphatasia-Associated Mineralization Deficiencies In Vitro by Phosphate/Pyrophosphate Modulation in Periodontal Ligament Cells

Autor(es)

Rodrigues, Thaisangela L. ^[1] ; Foster, Brian L. ^{[2, 3]} ; Silverio, Karina G. ^[1] ; Martins, Luciane ^[1] ; Casati, Marcio Z. ^[1] ; Sallum, Enilson A. ^[1] ; Somerman, Martha J. ^{[2, 3]} ; Nociti, Jr., Francisco H. ^{[2, 1]}

Afiliação do(s) autor(es)

^[1] Univ Estadual Campinas, Dept Prosthodont & Periodont, Div Periodont, Sch Dent, Sao Paulo - Brazil

^[2] Univ Washington, Sch Dent, Dept Periodont, Seattle, WA 98195 - USA

^[3] Univ Washington, Sch Dent, Dept Oral Biol, Seattle, WA 98195 - USA

• Tipo de documento: Artigo Científico
• Fonte: Journal of Periodontology; v. 83, n. 5, p. 653-663, MAY 2012.
• Citações Web of Science: 5

Resumo

Background: Mutations in the liver/bone/kidney alkaline phosphatase (ALPL) gene in hypophosphatasia (HPP) reduce the function of tissue non-specific alkaline phosphatase (ALP), resulting in increased pyrophosphate (PPi) and a severe deficiency in acellular cementum. We hypothesize that exogenous phosphate (P-i) would rescue the in vitro mineralization capacity of periodontal ligament (PDL) cells harvested from HPP-diagnosed patients, by correcting the P-i/PPi ratio and modulating expression of genes involved with P-i/PPi metabolism. Methods: Ex vivo and in vitro analyses were used to identify mechanisms involved in HPP-associated PDL/tooth root deficiencies. Constitutive expression of PPi-associated genes was contrasted in PDL versus pulp tissues obtained from healthy individuals. Primary PDL cell cultures from patients with HPP (monozygotic twin males) were established to assay ALP activity, in vitro mineralization, and gene expression. Exogenous P-i was provided to correct the P-i/PPi ratio. Results: PDL tissues obtained from healthy individuals featured higher basal expression of key PPi regulators, genes ALPL, progressive ankylosis protein (ANKH), and ectonucleotide pyrophosphatase/phosphodiesterase 1 (ENPP1), versus paired pulp tissues. A novel ALPL mutation was identified in the twin patients with HPP enrolled in this study. Compared to controls, HPP-PDL cells exhibited significantly reduced ALP and mineralizing capacity, which were rescued by addition of 1 mM P-i. Dysregulated expression of PPi regulatory genes ALPL, ANKH, and ENPP1 was also corrected by adding P-i, although other matrix markers evaluated in our study remained downregulated. Conclusion: These findings underscore the importance of controlling the P-i/PPi ratio toward development of a functional periodontal apparatus and support P-i/PPi imbalance as the etiology of HPP-associated cementum defects. J Periodontol 2012;83:653-663. (AU)

• Processo FAPESP: 08/00534-7 - Análise diferencial da regulação de genes associados ao metabolismo do fosfato de células da polpa e ligamento periodontal em indivíduos saudáveis e com hipofosfatasia
• Beneficiário: Márcio Zaffalon Casati
• Modalidade de apoio: Auxílio à Pesquisa - Regular
• Processo FAPESP: 07/08192-5 - Análise diferencial da regulação de genes associados ao metabolismo do fosfato de células da polpa e ligamento periodontal em indivíduos saudáveis e com hipofosfatasia
• Beneficiário: Thaisângela Rodrigues Lopes e Silva Gomes
• Modalidade de apoio: Bolsas no Brasil - Doutorado