This article has been accepted for publication and undergone full peer review but has not been through the copyediting, typesetting, pagination and proofreading process, which may lead to differences between this version and the Version of Record. Please cite this article as doi: [10.1002/jcb.24691]
Osteoblast adhesion dynamics: A possible role for ROS and LMW-PTP†
© 2013 Wiley Periodicals, Inc.
- Accepted manuscript online: 14 OCT 2013 02:46AM EST
- Manuscript Accepted: 7 OCT 2013
- Manuscript Revised: 16 SEP 2013
- Manuscript Received: 23 MAR 2012
- Cited By
Reactive oxygen species (ROS) modulate a variety of intracellular events, but their role in osteoblast adhesion and spreading remains unclear. ROS is a very-known physiological modulators of Protein Tyrosine Phosphatases activities, mainly to Low Molecular Weight Protein Tyrosine Phosphatase (LMW-PTP) activity. As this biological mechanism is not clear in osteoblast adhesion, we decided to investigate ROS levels and phosphorylations of FAK and Src, identifying these proteins as potential substrates to LMW-PTP activity. Our results showed that during osteoblast adhesion/spreading (30 minutes and 2 hours of seeding) the intracellular ROS content (hydrogen peroxide) is finely regulated by an effective anti-oxidant system [catalase and Superoxide Dismutase (SOD) activities were evaluated]. During the first 30 min of adhesion, there was an increase in ROS production and a concomitant increase in Focal Adhesion Kinase (FAK) activity after its phosphorylation at Tyrosine 397 (Y397). Moreover, after 2 h there was a decrease in ROS content and FAK phosphorylation. There was no significant change in LMW-PTP expression at 30 min or 2 h. In order to validate our hypothesis that LMW-PTP is able to control FAK activity by modulating its phosphorylation status, we decided to overexpress and silence LMW-PTP in this context. Our results showed that FAK phosphorylation at Y397 was increased and decreased in osteoblasts with silenced or overexpressed LMW-PTP, respectively. Together, these data show that ROS modulate FAK phosphorylation by an indirect way, suggesting that a LMW-PTP/FAK supra-molecular complex is involved in transient responses during osteoblast adhesion and spreading. J. Cell. Biochem. © 2013 Wiley Periodicals, Inc.