Suppressive effect of alpha2 Heremans-Schmid glycoprotein on in vitro calcification of osteogenesis.
BACKGROUND
alpha(2) Heremans-Schmid glycoprotein (alpha(2)HS glycoprotein) is predominantly found in bone. To date, we have investigated plasma alpha(2)HS levels in immature babies and neonates as well as the histological distribution in various neonatal tissues in order to clarify its physiological significance. In an effort to understand the physiological function of alpha(2)HS glycoprotein in bones, we studied the effects of alpha(2)HS glycoprotein in cultured osteogenesis model using rat marrow cells.


METHODS
We added different concentrations of alpha(2)HS glycoprotein to cultured marrow cells, including osteoblasts in the presence of dexamethasone, in an attempt to elucidate the effects of alpha(2)HS glycoprotein on osteoblast growth and bone calcification in vitro.


RESULTS
The results showed that total DNA content was significantly increased with 0.2-20 nM (f.c.) alpha(2)HS glycoprotein, but was neither suppressed nor increased with 200 nM (f.c.) alpha(2)HS glycoprotein. Although ALP activity increased with 0.2 or 2 nM (f.c.) alpha(2)HS glycoprotein, it decreased with 20 or 200 nM (f.c.) alpha(2)HS glycoprotein. While 0.2 nM (f.c.) alpha(2)HS glycoprotein had no effect on calcium or osteocalcin content, 2 nM (f.c.) alpha(2)HS glycoprotein decreased both calcium content and osteocalcin content by about half, and no calcium or osteocalcin was observed with 20 or 200 nM (f.c.). Calcium staining of cultured marrow cells revealed that the number of stained cell tubercles decreased in a concentration-dependent manner.


CONCLUSIONS
These findings suggest that alpha(2)HS glycoprotein regulates the growth of osteoblasts and acts as an inhibitory factor in the regulation of bone calcification.
Division of Neonatal Intensive Care, Center of Perinatal Medicine, Nara Medical University Hospital, Japan.
Yuji
Y
Yoshida
Yukihiro
Y
Takahashi
Takafumi
T
Yoshikawa
Akitaka
A
Nonomura
Akira
A
Yoshioka
D000818:Animals; D001798:Blood Proteins / Q000494:pharmacology / Q000502:physiology*; D002113:Calcification, Physiologic / Q000187:drug effects / Q000502:physiology*; D002478:Cells, Cultured; D008297:Male; D010012:Osteogenesis / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D060749:alpha-2-HS-Glycoprotein
D001798:Blood Proteins; D060749:alpha-2-HS-Glycoprotein