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- Halling Linder, Cecilia, et al.
(author)
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Bone Alkaline Phosphatase and Tartrate-Resistant Acid Phosphatase: Potential Co-regulators of Bone Mineralization
- 2017
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In: Calcified Tissue International. - : SPRINGER. - 0171-967X .- 1432-0827. ; 101:1, s. 92-101
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Journal article (peer-reviewed)abstract
- Phosphorylated osteopontin (OPN) inhibits hydroxyapatite crystal formation and growth, and bone alkaline phosphatase (BALP) promotes extracellular mineralization via the release of inorganic phosphate from the mineralization inhibitor inorganic pyrophosphate (PPi). Tartrate-resistant acid phosphatase (TRAP), produced by osteoclasts, osteoblasts, and osteocytes, exhibits potent phosphatase activity towards OPN; however, its potential capacity as a regulator of mineralization has not previously been addressed. We compared the efficiency of BALP and TRAP towards the endogenous substrates for BALP, i.e., PPi and pyridoxal 5-phosphate (PLP), and their impact on mineralization in vitro via dephosphorylation of bovine milk OPN. TRAP showed higher phosphatase activity towards phosphorylated OPN and PPi compared to BALP, whereas the activity of TRAP and BALP towards PLP was comparable. Bovine milk OPN could be completely dephosphorylated by TRAP, liberating all its 28 phosphates, whereas BALP dephosphorylated at most 10 phosphates. OPN, dephosphorylated by either BALP or TRAP, showed a partially or completely attenuated phosphorylation-dependent inhibitory capacity, respectively, compared to native OPN on the formation of mineralized nodules. Thus, there are phosphorylations in OPN important for inhibition of mineralization that are removed by TRAP but not by BALP. In conclusion, our data indicate that both BALP and TRAP can alleviate the inhibitory effect of OPN on mineralization, suggesting a potential role for TRAP in skeletal mineralization. Further studies are warranted to explore the possible physiological relevance of TRAP in bone mineralization.
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| 2. |
- Perez-Segura, Pedro, et al.
(author)
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BRCA2 gene mutations and coagulation-associated biomarkers
- 2016
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In: Thrombosis and Haemostasis. - 0340-6245. ; 115:2, s. 415-423
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Journal article (peer-reviewed)abstract
- Thromboembolic events are the second cause of death in cancer patients, although the mechanisms underlying this increased thromboembolic risk remain unclear. The aims of this study were to examine whether BRCA2 gene mutations may modify the circulating levels of thrombocoagulation biomarkers and whether breast cancer development may influence changes in such circulating biomarkers. The study was performed in 25 women with mutations in the BRCA2 gene (n=12 breast cancer, n=13 breast cancer-free) and in 13 BRCA2 nonmutant controls. Results revealed that plasma levels of fibrinogen gamma chain isotypes 2 and 3, haptoglobin isotypes 4 and 5, serotransferrin isotypes 3 and 4 and convertase C3/C5 isotypes 4 and 5 were significantly higher in BRCA2 mutation carriers compared to controls. However, plasma levels of vitamin D binding protein isotype 1 and alpha1-antitrypsin isotypes 2, 3 and 4 were significantly decreased in BRCA2 mutation carriers compared to controls. Plasma expression of PF4 and P-selectin was significantly higher in BRCA2 mutations carriers than in controls. BRCA2 truncated mutations conserving a binding region for RAD51 were associated with increased plasma levels of alpha1-antitrypsin isotypes 3 and 4 with respect to women showing BRCA2 mutations that loss the binding RD51 region to BRCA2. Only plasma levels of vitamin D binding protein isotypes 1 and 3 were significantly reduced and alpha 1-antitrypsin isotype 1 was increased in cancer-free BRCA2 mutation carriers compared to BRCA2 mutation carriers with breast cancer. The presence of BRCA2 mutations is associated with increased plasma levels of thrombo-coagulating- related proteins, which are independent to breast cancer development.
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