Spaceflight and bed rest induce loss of bone mass. A number of in vivo and in vitro studies have been conducted to clarify the mechanisms, however, the results have been conflicting. The purpose of this study was to investigate the effects of gravity unloading on proliferation, phenotypes, and apoptosis of normal @entity1 osteoblastic cells in the presence of @entity3873 . We used a vector-averaged gravity condition generated by clinostat rotation to simulate gravity unloading. Clinostat rotation did not affect the cell proliferation. On the first day, the mRNA levels for osteocalcin, @entity3064 , @entity8087 , @entity17894 , @entity5298 , and @entity5299 were reduced by clinostat rotation to 21%, 65%, 62%, 52%, 43%, and 54% of control, respectively. @entity3064 activity was decreased to 75% of control. On the second day, the mRNA levels for osteocalcin and @entity5298 were reduced to 77% and 61% of control, respectively. The decreased @entity17894 mRNA level might be responsible for the reduction for mRNA levels for osteocalcin, @entity5298 , and @entity5299 . Clinostat rotation increased the pro-apoptotic index ( @entity589 / @entity588 ratio) but did not induce apoptosis due to the simultaneous upregulation of the anti-apoptotic @entity9846 . Reduction of osteoblast responsiveness to @entity3873 might be involved in @entity2331 that is induced by gravity unloading.

Suppression of osteoblastic phenotypes and modulation of pro- and anti-apoptotic features in normal XXXX osteoblastic cells under a vector-averaged gravity condition.

@entity1 :: ('9606', 'Species') :: ['human'] @entity8087 :: ('860', 'Gene') :: ['CBFA1'] @entity589 :: ('581', 'Gene') :: ['Bax'] @entity588 :: ('596', 'Gene') :: ['Bcl-2'] @entity9846 :: ('331', 'Gene') :: ['XIAP'] @entity3873 :: ('MESH:D002117', 'Chemical') :: ['1alpha,25-dihydroxyvitamin D3'] @entity5298 :: ('8600', 'Gene') :: ['RANKL'] @entity5299 :: ('690', 'Gene') :: ['OPG'] @entity2331 :: ('MESH:D001851', 'Disease') :: ['osteopenia'] @entity17894 :: ('7421', 'Gene') :: ['VDR'] @entity3064 :: ('470', 'Gene') :: ['ALP']
@entity1 :: (9606,Species) :: ['human']
