Osteocalcin promotes differentiation of osteoclast progenitors from murine long‐term bone marrow cultures

Abstract

Murine long-term bone marrow cultures (LTBMCs) were used to generate hematopoietic cells free from marrow stromal cells. These progenitor cells were treated with GM-CSF (5 U/ml) with or without rat bone osteocalcin or rat serum albumin in either alpha-MEM with 2% heat-inactivated horse serum alone (alpha) or supplemented with 10% L-cell-conditioned medium (as a source of M-CSF) (L10). Few substrate-attached cells survived in basal alpha medium, but when treated with L10 medium or GM-CSF, they survived and proliferated. Osteocalcin did not significantly affect survival or proliferation. Subcultures of cells treated with GM-CSF had large numbers of multinucleated cells, more than half of which were tartrate-resistant acid phosphatase-positive (TRAP). Osteocalcin further promoted the development of TRAP-positive multinucleated cells; a dose of 0.7 microgram/ml osteocalcin promoted osteoclastic differentiation by 60%. Using a novel microphotometric assay, we detected significantly more tartrate-resistant acid phosphatase activity in the osteocalcin plus GM-CSF group (75.6 +/- 14.2) than in GM-CSF alone (53.3 +/- 7.3). In the absence of M-CSF, GM-CSF stimulated tartrate-resistant acid phosphatase activity, but osteocalcin did not have an additional effect. These studies indicate that osteocalcin promotes osteoclastic differentiation of a stromal-free subpopulation of hematopoietic progenitors in the presence of GM-CSF and L-cell-conditioned medium. These results are consistent with the hypothesis that this bone-matrix constituent plays a role in bone resorption.

O‐phospho‐L‐serine modified calcium phosphate cements – material properties, in vitro and in vivo investigations

“…collagen type I) and non-collagenous bone matrix proteins, like osteocalcin (OC), bone sialoprotein (BSP), osteopontin (OPN) or growth factors like bone morphogenetic proteins (BMP) to modify the cements [10][11][12][13][14][15]. These compounds are known to be very effective in stimulating bone cell activity and bone healing [16][17][18][19][20][21][22]. Furthermore, these molecules are able to support a bone like HAP morphology [21][22][23][24][25][26][27], mostly because of specific peptide sequences and functional substituents like phosphate and carboxylic groups.…”

New Insights into the Complexation of Lead(II) by 1,4,7,10‐Tetrakis(carbamoylmethyl)‐1,4,7,10‐tetraazacyclododecane (DOTAM): Structural, Thermodynamic, and Kinetic Studies

“…[5,[7][8][9] Besides anemia, lead-induced enzymatic inhibition causes a range of other pathologies. One can quote, for example, the replacement of calcium by lead in synaptogamin [5,10] or osteocalcin (bone Gla protein), [11][12][13] which induces nervous system aftereffects or delays osseous growth, respectively.…”

Structural Evidence of a Fourth Gla Residue in Fish Osteocalcin: Biological Implications,

“…Several studies also suggested a role for osteocalcin as a matrix signal for the recruitment and differentiation of osteoclasts (18)(19)(20)(21). However, the understanding of the physiological function of osteocalcin was substantially advanced when a model for osteocalcin gene deficient mice was generated through mouse genetics (22).…”