Activation of extracellular-signal regulated kinase (ERK1/2) by fluid shear is Ca2+- and ATP-dependent in MC3T3-E1 osteoblasts

Dawei Liu, Damian C Genetos, Ying Shao, Derik J. Geist, Jiliang Li, Hua Zhu Ke, Charles H. Turner, Randall L. Duncan

Research output: Contribution to journalArticle

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Abstract

To determine the role of Ca2+ signaling in activation of the Mitogen-Activated Protein Kinase (MAPK) pathway, we subjected MC3T3-E1 pre-osteoblastic cells to inhibitors of Ca2+ signaling during application of fluid shear stress (FSS). FSS only activated ERK1/2, rapidly inducing phosphorylation within 5 min of the onset of shear. Phosphorylation of ERK1/2 (pERK1/2) was significantly reduced when Cai2+ was chelated with BAPTA or when Ca2+ was removed from the flow media. Inhibition of both the L-type voltage-sensitive Ca2+ channel and the mechanosensitive cation-selective channel blocked FSS-induced pERK1/2. Inhibition of phospholipase C with U73122 significantly reduced pERK1/2. This inhibition did not result from blockage of intracellular Ca2+ release, but a loss of PKC activation. Recent data suggests a role of ATP release and purinergic receptor activation in mechanotransduction. Apyrase-mediated hydrolysis of extracellular ATP completely blocked FSS-induced phosphorylation of ERK1/2, while the addition of exogenous ATP to static cells mimicked the effects of FSS on pERK1/2. Two P2 receptors, P2Y2 and P2X7, have been associated with the anabolic responses of bone to mechanical loading. Using both iRNA techniques and primary osteoblasts isolated from P2X7 knockout mice, we found that the P2X7, but not the P2Y2, purinergic receptor was involved in ERK1/2 activation under FSS. These data suggest that FSS-induced ERK1/2 phosphorylation requires Ca2+-dependent ATP release, however both increased Cai2+ and PKC activation are needed for complete activation. Further, this ATP-dependent ERK1/2 phosphorylation is mediated through P2X7, but not P2Y2, purinergic receptors.

Original languageEnglish (US)
Pages (from-to)644-652
Number of pages9
JournalBone
Volume42
Issue number4
DOIs
StatePublished - Apr 2008

Fingerprint

Mitogen-Activated Protein Kinase 1
Osteoblasts
Adenosine Triphosphate
Phosphorylation
Purinergic P2Y2 Receptors
Purinergic P2X7 Receptors
Apyrase
Purinergic P2 Receptors
Purinergic Receptors
Type C Phospholipases
Mitogen-Activated Protein Kinases
Knockout Mice
Cations
Hydrolysis
Bone and Bones

Keywords

  • ATP
  • Calcium channel
  • Fluid shear stress
  • Osteoblast
  • Purinergic

ASJC Scopus subject areas

  • Physiology
  • Hematology

Cite this

Activation of extracellular-signal regulated kinase (ERK1/2) by fluid shear is Ca2+- and ATP-dependent in MC3T3-E1 osteoblasts. / Liu, Dawei; Genetos, Damian C; Shao, Ying; Geist, Derik J.; Li, Jiliang; Ke, Hua Zhu; Turner, Charles H.; Duncan, Randall L.

In: Bone, Vol. 42, No. 4, 04.2008, p. 644-652.

Research output: Contribution to journalArticle

Liu, Dawei ; Genetos, Damian C ; Shao, Ying ; Geist, Derik J. ; Li, Jiliang ; Ke, Hua Zhu ; Turner, Charles H. ; Duncan, Randall L. / Activation of extracellular-signal regulated kinase (ERK1/2) by fluid shear is Ca2+- and ATP-dependent in MC3T3-E1 osteoblasts. In: Bone. 2008 ; Vol. 42, No. 4. pp. 644-652.
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AU - Shao, Ying

AU - Geist, Derik J.

AU - Li, Jiliang

AU - Ke, Hua Zhu

AU - Turner, Charles H.

AU - Duncan, Randall L.

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