Role of PHOSPHO1 in Periodontal Development and Function

Zweifler, Laura E.; Ao, Min; Yadav, Manisha; Kuss, Pia; Narisawa, Sonoko; Kolli, Tamara N.; Wimer, Helen F.; Farquharson, Colin; Somerman, M. J.; Millán, José Luis; Foster, Brian L.

doi:10.1177/0022034516640246

Cited by 23 publications

(26 citation statements)

References 34 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…PHOSPHO1 is a phosphatase indicated to be important in matrix vesicle initiated mineralization of bone and mantle dentin [72–77]. In recent studies on periodontal development in Phospho1 −/− mice, we found that while alveolar bone and cellular cementum displayed mineralization defects, acellular cementum development appeared unperturbed and no periodontal dysfunction was evident up to 3 months of age [78]. The implications of down-regulated Phospho1 mRNA remain unclear, though it is intriguing that loss of BSP causes increased expression of Alpl , a critical positive regulator of acellular cementum formation [6, 15, 79].…”

Section: Discussionmentioning

confidence: 99%

Overlapping functions of bone sialoprotein and pyrophosphate regulators in directing cementogenesis

Chavez

Chu

et al. 2017

Bone

Self Cite

View full text Add to dashboard Cite

Although acellular cementum is essential for tooth attachment, factors directing its development and regeneration remain poorly understood. Inorganic pyrophosphate (PPi), a mineralization inhibitor, is a key regulator of cementum formation: tissue-nonspecific alkaline phosphatase (Alpl/TNAP) null mice (increased PPi) feature deficient cementum, while progressive ankylosis protein (Ank/ANK) null mice (decreased PPi) feature increased cementum. Bone sialoprotein (Bsp/BSP) and osteopontin (Spp1/OPN) are multifunctional extracellular matrix components of cementum proposed to have direct and indirect effects on cell activities and mineralization. Studies on dentoalveolar development of Bsp knockout (Bsp−/−) mice revealed severely reduced acellular cementum, however underlying mechanisms remain unclear. The similarity in defective cementum phenotypes between Bsp−/− mice and Alpl−/− mice (the latter featuring elevated PPi and OPN), prompted us to examine whether BSP is operating by modulating PPi-associated genes. Genetic ablation of Bsp caused a 2-fold increase in circulating PPi, altered mRNA expression of Alpl, Spp1, and Ank, and increased OPN protein in the periodontia. Generation of a Bsp knock-out (KO) cementoblast cell line revealed significantly decreased mineralization capacity, 50% increased PPi in culture media, and increased Spp1 and Ank mRNA expression. While addition of 2 μg/ml recombinant BSP altered Spp1, Ank, and Enpp1 expression in cementoblasts, changes resulting from this dose were not dependent on the integrin-binding RGD motif or by genetic ablation of Ank on the Bsp−/− MAPK/ERK signaling pathway. Decreasing PPi mouse background reestablished cementum formation, allowing more than 3-fold increased acellular cementum volume compared to WT. However, deleting Ank did not fully compensate for the absence of BSP. Bsp−/−;Ank−/− double-deficient mice exhibited mean 20–27% reduced cementum thickness and volume compared to Ank−/− mice. From these data, we conclude that the perturbations in PPi metabolism are not solely driving the cementum pathology in Bsp−/− mice, and that PPi is more potent than BSP as a cementum regulator, as shown by the ability to override loss of BSP by lowering PPi. We propose that BSP and PPi work in concert to direct mineralization in cementum and likely other mineralized tissues.

show abstract

Section: Discussionmentioning

confidence: 99%

Overlapping functions of bone sialoprotein and pyrophosphate regulators in directing cementogenesis

Chavez

Chu

et al. 2017

Bone

Self Cite

View full text Add to dashboard Cite

show abstract

“…In situ hybridization (ISH) with antisense Spp1 , Col1a1, Ibsp , Bglap , and Enpp1 probes was performed on deparaffinized histological sections and visualized with fast red dye (Advanced Cell Diagnostics, Newark, CA), using hematoxylin as a counterstain, as previously described [32]. …”

Section: Methodsmentioning

confidence: 99%

Osteopontin regulates dentin and alveolar bone development and mineralization

Foster

Salmon

et al. 2018

Bone

Self Cite

101

View full text Add to dashboard Cite

The periodontal complex is essential for tooth attachment and function and includes the mineralized tissues, cementum and alveolar bone, separated by the unmineralized periodontal ligament (PDL). To gain insights into factors regulating cementum-PDL and bone-PDL borders and protecting against ectopic calcification within the PDL, we employed a proteomic approach to analyze PDL tissue from progressive ankylosis knock-out (Ank) mice, featuring reduced PP, rapid cementogenesis, and excessive acellular cementum. Using this approach, we identified the matrix protein osteopontin (Spp1/OPN) as an elevated factor of interest in Ank mouse molar PDL. We studied the role of OPN in dental and periodontal development and function. During tooth development in wild-type (WT) mice, Spp1 mRNA was transiently expressed by cementoblasts and strongly by alveolar bone osteoblasts. Developmental analysis from 14 to 240days postnatal (dpn) indicated normal histological structures in Spp1 comparable to WT control mice. Microcomputed tomography (micro-CT) analysis at 30 and 90dpn revealed significantly increased volumes and tissue mineral densities of Spp1 mouse dentin and alveolar bone, while pulp and PDL volumes were decreased and tissue densities were increased. However, acellular cementum growth was unaltered in Spp1 mice. Quantitative PCR of periodontal-derived mRNA failed to identify potential local compensators influencing cementum in Spp1 vs. WT mice at 26dpn. We genetically deleted Spp1 on the Ank mouse background to determine whether increased Spp1/OPN was regulating periodontal tissues when the PDL space is challenged by hypercementosis in Ank mice. Ank; Spp1 double deficient mice did not exhibit greater hypercementosis than that in Ank mice. Based on these data, we conclude that OPN has a non-redundant role regulating formation and mineralization of dentin and bone, influences tissue properties of PDL and pulp, but does not control acellular cementum apposition. These findings may inform therapies targeted at controlling soft tissue calcification.

show abstract

“…Animals were sacrificed in accordance with guidelines of the Animal Care and Use Committee at the Sanford Burnham Prebys Medical Discovery Institute and National Institutes of Health (NIH). Breeding, genotyping, and characterization of Phospho1 −/− mice has been described previously (Yadav et al, 2011 ; Zweifler et al, 2016 ). Eleven mandibles each from control and Phospho1 −/− mice were chosen for histology and microscopy studies.…”

Section: Methodsmentioning

confidence: 99%

Intravesicular Phosphatase PHOSPHO1 Function in Enamel Mineralization and Prism Formation

Pandya

Rosene

Farquharson³

et al. 2017

Front. Physiol.

View full text Add to dashboard Cite

The transport of mineral ions from the enamel organ-associated blood vessels to the developing enamel crystals involves complex cargo packaging and carriage mechanisms across several cell layers, including the ameloblast layer and the stratum intermedium. Previous studies have established PHOSPHO1 as a matrix vesicle membrane-associated phosphatase that interacts with matrix vesicles molecules phosphoethanolamine and phosphocholine to initiate apatite crystal formation inside of matrix vesicles in bone. In the present study, we sought to determine the function of Phospho1 during amelogenesis. PHOSPHO1 protein localization during amelogenesis was verified using immunohistochemistry, with positive signals in the enamel layer, ameloblast Tomes' processes, and in the walls of ameloblast secretory vesicles. These ameloblast secretory vesicle walls were also labeled for amelogenin and the exosomal protein marker HSP70 using immunohistochemistry. Furthermore, PHOSPHO1 presence in the enamel organ was confirmed by Western blot. Phospho1−/− mice lacked sharp incisal tips, featured a significant 25% increase in total enamel volume, and demonstrated a significant 2-fold reduction in silver grain density of von Kossa stained ground sections indicative of reduced mineralization in the enamel layer when compared to wild-type mice (p < 0.001). Scanning electron micrographs of Phospho1−/− mouse enamel revealed a loss of the prominent enamel prism “picket fence” structure, a loss of parallel crystal organization within prisms, and a 1.56-fold increase in enamel prism width (p < 0.0001). Finally, EDS elemental analysis demonstrated a significant decrease in phosphate incorporation in the enamel layer when compared to controls (p < 0.05). Together, these data establish that the matrix vesicle membrane-associated phosphatase PHOSPHO1 is essential for physiological enamel mineralization. Our findings also suggest that intracellular ameloblast secretory vesicles have unexpected compositional similarities with the extracellular matrix vesicles of bone, dentin, and cementum in terms of vesicle membrane composition and intravesicular ion assembly.

show abstract

Role of PHOSPHO1 in Periodontal Development and Function

Cited by 23 publications

References 34 publications

Overlapping functions of bone sialoprotein and pyrophosphate regulators in directing cementogenesis

Overlapping functions of bone sialoprotein and pyrophosphate regulators in directing cementogenesis

Osteopontin regulates dentin and alveolar bone development and mineralization

Intravesicular Phosphatase PHOSPHO1 Function in Enamel Mineralization and Prism Formation

Contact Info

Product

Resources

About