Differential stimulation of prostaglandin G/H synthase-2 in osteocytes and other osteogenic cells by pulsating fluid flow.
Mechanical stress produces flow of fluid in the osteocytic lacunar-canalicular network, which is likely the physiological signal for the adaptive response of bone. We compared the induction of prostaglandin G/H synthase-2 (PGHS-2) by pulsating fluid flow (PFF) and serum in osteocytes, osteoblasts, and periosteal fibroblasts, isolated from 18-day-old fetal chicken calvariae. A serum-deprived mixed population of primarily osteocytes and osteoblasts responded to serum with a two- to threefold induction of PGHS-2 mRNA. Serum stimulated PGHS-2-derived PGE(2) release from osteoblasts and osteocytes but not from periosteal fibroblasts as NS-398, a PGHS-2 blocker, inhibited PGE(2) release from osteocytes and osteoblasts with 65%, but not that from periosteal fibroblasts. On the other hand PFF (0.7 Pa, 5 Hz) stimulated (3 fold) PGHS-2 mRNA only in OCY. The related PGE(2) response could be completely inhibited by NS-398. We conclude that osteocytes have a higher intrinsic sensitivity for loading-derived fluid flow than osteoblasts or periosteal fibroblasts.
Westbroek
I
I
Department of Molecular Cell Biology, Leiden University Medical Center, Leiden, The Netherlands. I.Westbroek@lumc.nl
Ajubi
N E
NE
Alblas
M J
MJ
Semeins
C M
CM
Klein-Nulend
J
J
Burger
E H
EH
Nijweide
P J
PJ
D000818:Animals; D002478:Cells, Cultured; D002642:Chick Embryo; D051546:Cyclooxygenase 2; D004789:Enzyme Activation; D004790:Enzyme Induction; D005347:Fibroblasts / Q000378:metabolism; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D010006:Osteoblasts / Q000378:metabolism; D010011:Osteocytes / Q000201:enzymology*; D011451:Prostaglandin-Endoperoxide Synthases / Q000235:genetics / Q000378:metabolism*; D011673:Pulsatile Flow / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism
D007527:Isoenzymes; D012333:RNA, Messenger; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases