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Extracellular calcium chronically induced human osteoblasts effects: Specific modulation of osteocalcin and collagen type XV
Author(s) -
Gabusi Elena,
Manferdini Cristina,
Grassi Francesco,
Piacentini Anna,
Cattini Luca,
Filardo Giuseppe,
Lambertini Elisabetta,
Piva Roberta,
Zini Nicoletta,
Facchini Andrea,
Lisignoli Gina
Publication year - 2012
Publication title -
journal of cellular physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.529
H-Index - 174
eISSN - 1097-4652
pISSN - 0021-9541
DOI - 10.1002/jcp.24001
Subject(s) - osteocalcin , bone sialoprotein , osteoblast , extracellular , microbiology and biotechnology , chemistry , type i collagen , alkaline phosphatase , runx2 , calcium , endocrinology , cell growth , intracellular , medicine , biology , biochemistry , in vitro , organic chemistry , enzyme
Fluctuation in extracellular calcium (Ca 2+ ) concentration occurs during bone remodeling. Free ionized Ca 2+ plays a critical role in regulating osteoblast functions. We analyzed the effects of different concentrations of free ionized Ca 2+ (0.5, 1.3, and 2.6 mM) on human osteoblasts and we evaluated osteoblastic phenotype (marker expression and cell morphology) and functions (osteogenic differentiation, cell proliferation, and cell signaling). Our data show human osteoblasts that chronically stimulated with 0.5, 1.3, or 2.6 mM Ca 2+ significantly increase intracellular content of alkaline phosphatase, collagen type I, osteocalcin, and bone sialoprotein, whereas collagen type XV was down‐modulated and RUNX2 expression was not affected. We also found a Ca 2+ concentration‐dependent increase in osteogenic differentiation and cell proliferation, associated to an increase of signaling protein PLCβ1 and p‐ERK. Human osteoblast morphology was affected by Ca 2+ as seen by the presence of numerous nucleoli, cells in mitosis, cell junctions, and an increased number of vacuoles. In conclusion, our data show a clear phenotypical and functional effect of extracellular Ca 2+ on human osteoblasts and support the hypothesis of a direct role of this cation in the bone remodeling processes. J. Cell. Physiol. 227: 3151–3161, 2012. © 2011 Wiley Periodicals, Inc.