Progressive calcification of elastic fibers is typical of Pseudoxanthoma elasticum (PXE), a rare genetic disease due to mutations in the ABCC6 gene.The pathogenesis of mineral- ization is only partially known.1 Previous studies on dermal fibroblasts from PXE patients demonstrated that the calcifica- tion process is associated to impaired carboxylation of matrix- gla-protein that, in its active form, binds to calcium, therefore inhibiting mineralization.2 However, the recent observation that PXE fibroblasts exhibit also a significant upregulation of alka- line phosphatase (TNAP) activity suggested that an abnormal phosphate metabolism may take place within soft connective tis- sues, thus contributing to ectopic calcification.3 To improve the understanding of PXE it was developed a transgenic mouse model by specifically inactivating the Abcc6 gene.4 Consistently, Abcc6-/- mice recapitulate several histopathological findings typ- ical of PXE, including the slow progression of the disease.5 Aim of the present study was to isolate fibroblasts from Abcc6+/+ and Abcc6-/- mice of different ages (i.e. before and after the devel- opment of ectopic calcification) and to investigate proteins con- trolling phosphate levels in the extracellular matrix. Results demonstrate a down-regulation of pyrophosphatase/phosphodi- esterase 1, of progressive ankylosis protein and of osteopontin, whereas bone morphogenetic protein 2 and TNAP activity were up-regulated in fibroblasts from Abcc6-/- animals. These data support the hypothesis that in PXE the unbalanced ratio between factors locally controlling both calcium and phosphate homeostasis are crucial in triggering tissue calcification.

DIFFERENTIALLY EXPRESSED PROTEINS IN FIBROBLASTS FROM Abcc6-/- AND Abcc6+/+ MICE HIGHLIGHT THE ROLE OF A LOCALLY ALTERED PHOSPHATE METABOLISM IN THE OCCURRENCE OF ECTOPIC CALCIFICATION / Bartolomeo, Angelica; Boraldi, Federica; Uitto, J.; Quaglino, Daniela. - In: EUROPEAN JOURNAL OF HISTOCHEMISTRY. - ISSN 1121-760X. - STAMPA. - 57/suppl. 2:(2013), pp. 3-3. ((Intervento presentato al convegno XXXIII Riunione Nazionale SISC tenutosi a Pavia nel 3-4 October.

DIFFERENTIALLY EXPRESSED PROTEINS IN FIBROBLASTS FROM Abcc6-/- AND Abcc6+/+ MICE HIGHLIGHT THE ROLE OF A LOCALLY ALTERED PHOSPHATE METABOLISM IN THE OCCURRENCE OF ECTOPIC CALCIFICATION

BARTOLOMEO, ANGELICA;BORALDI, Federica;QUAGLINO, Daniela
2013

Abstract

Progressive calcification of elastic fibers is typical of Pseudoxanthoma elasticum (PXE), a rare genetic disease due to mutations in the ABCC6 gene.The pathogenesis of mineral- ization is only partially known.1 Previous studies on dermal fibroblasts from PXE patients demonstrated that the calcifica- tion process is associated to impaired carboxylation of matrix- gla-protein that, in its active form, binds to calcium, therefore inhibiting mineralization.2 However, the recent observation that PXE fibroblasts exhibit also a significant upregulation of alka- line phosphatase (TNAP) activity suggested that an abnormal phosphate metabolism may take place within soft connective tis- sues, thus contributing to ectopic calcification.3 To improve the understanding of PXE it was developed a transgenic mouse model by specifically inactivating the Abcc6 gene.4 Consistently, Abcc6-/- mice recapitulate several histopathological findings typ- ical of PXE, including the slow progression of the disease.5 Aim of the present study was to isolate fibroblasts from Abcc6+/+ and Abcc6-/- mice of different ages (i.e. before and after the devel- opment of ectopic calcification) and to investigate proteins con- trolling phosphate levels in the extracellular matrix. Results demonstrate a down-regulation of pyrophosphatase/phosphodi- esterase 1, of progressive ankylosis protein and of osteopontin, whereas bone morphogenetic protein 2 and TNAP activity were up-regulated in fibroblasts from Abcc6-/- animals. These data support the hypothesis that in PXE the unbalanced ratio between factors locally controlling both calcium and phosphate homeostasis are crucial in triggering tissue calcification.
57/suppl. 2
3
3
Bartolomeo, Angelica; Boraldi, Federica; Uitto, J.; Quaglino, Daniela
DIFFERENTIALLY EXPRESSED PROTEINS IN FIBROBLASTS FROM Abcc6-/- AND Abcc6+/+ MICE HIGHLIGHT THE ROLE OF A LOCALLY ALTERED PHOSPHATE METABOLISM IN THE OCCURRENCE OF ECTOPIC CALCIFICATION / Bartolomeo, Angelica; Boraldi, Federica; Uitto, J.; Quaglino, Daniela. - In: EUROPEAN JOURNAL OF HISTOCHEMISTRY. - ISSN 1121-760X. - STAMPA. - 57/suppl. 2:(2013), pp. 3-3. ((Intervento presentato al convegno XXXIII Riunione Nazionale SISC tenutosi a Pavia nel 3-4 October.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11380/1062596
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