Fluid shear stress induction of COX-2 protein and prostaglandin release in cultured MC3T3-E1 osteoblasts does not require intact microfilaments or microtubules.
Cultured osteoblasts express three major types of cytoskeleton: actin microfilaments, microtubules, and intermediate filaments. The cytoskeletal network is thought to play an important role in the transmission and conversion of a mechanical stimulus into a biochemical response. To examine a role for the three different cytoskeletal networks in fluid shear stress-induced signaling in osteoblasts, we individually disrupted actin microfilaments, micro-tubules, and intermediate filaments in MC3T3-E1 osteoblasts with multiple pharmacological agents. We subjected these cells to 90 min of laminar fluid shear stress (10 dyn/cm(2)) and compared the PGE(2) and PGI(2) release and induction of cyclooxygenase-2 protein to control cells with intact cytoskeletons. Disruption of actin microfilaments, microtubules, or intermediate filaments in MC3T3-E1 cells did not prevent a significant fluid shear stress-induced release of PGE(2) or PGI(2). Furthermore, disruption of actin microfilaments or microtubules did not prevent a significant fluid shear stress-induced increase in cyclooxygenase-2 protein levels. Disruption of intermediate filaments with acrylamide did prevent the fluid shear stress-induced increase in cyclooxygenase-2 but also prevented a PGE(2)-induced increase in cyclooxygenase-2. Thus none of the three major cytoskeletal networks are required for fluid shear stress-induced prostaglandin release. Furthermore, although neither actin microfilaments nor microtubules are required for fluid shear stress-induced increase in cyclooxygenase-2 levels, the role of intermediate filaments in regulation of cyclooxygenase-2 expression is less clear.
Norvell
Suzanne M
SM
Department of Cellular and Integrative Physiology, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
Ponik
Suzanne M
SM
Bowen
Deidre K
DK
Gerard
Rita
R
Pavalko
Fredrick M
FM
D008841:Actin Cytoskeleton / Q000378:metabolism*; D000818:Animals; D002478:Cells, Cultured; D051546:Cyclooxygenase 2; D007527:Isoenzymes / Q000096:biosynthesis* / Q000235:genetics; D051379:Mice; D008870:Microtubules / Q000378:metabolism*; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism*; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis* / Q000235:genetics; D011453:Prostaglandins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D033081:Shear Strength
D007527:Isoenzymes; D011453:Prostaglandins; D051546:Cyclooxygenase 2; D011451:Prostaglandin-Endoperoxide Synthases