Microtubules tune mechanotransduction through NOX2 and TRPV4 to decrease sclerostin abundance in osteocytes

James S. Lyons, Humberto C. Joca, Robert A. Law, Katrina M. Williams, Jaclyn P. Kerr, Guoli Shi, Ramzi J. Khairallah, Stuart S. Martin, K Konstantopoulos, Christopher W. Ward, Joseph P. Stains

Research output: Contribution to journalArticle

Abstract

The adaptation of the skeleton to its mechanical environment is orchestrated by mechanosensitive osteocytes, largely by regulating the abundance of sclerostin, a secreted inhibitor of bone formation. We defined a microtubuledependent mechanotransduction pathway that linked fluid shear stress to reactive oxygen species (ROS) and calcium (Ca2+) signals that led to a reduction in sclerostin abundance in cultured osteocytes. We demonstrated that microtubules stabilized by detyrosination, a reversible posttranslational modification of polymerized a-tubulin, determined the stiffness of the cytoskeleton, which set the mechanoresponsive range of cultured osteocytes to fluid shear stress. We showed that fluid shear stress through the microtubule network activated NADPH oxidase 2 (NOX2)-generated ROS that target the Ca2+ channel TRPV4 to elicit Ca2+ influx. Furthermore, tuning the abundance of detyrosinated tubulin affected cytoskeletal stiffness to define the mechanoresponsive range of cultured osteocytes to fluid shear stress. Finally, we demonstrated that NOX2-ROS elicited Ca2+ signals that activated the kinase CaMKII to decrease the abundance of sclerostin protein. Together, these discoveries may identify potentially druggable targets for regulating osteocyte mechanotransduction to affect bone quality.

Original languageEnglish (US)
Article numbereaan5748
JournalScience Signaling
Volume10
Issue number506
DOIs
StatePublished - Nov 21 2017

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Biology
  • Cell Biology

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    Lyons, J. S., Joca, H. C., Law, R. A., Williams, K. M., Kerr, J. P., Shi, G., Khairallah, R. J., Martin, S. S., Konstantopoulos, K., Ward, C. W., & Stains, J. P. (2017). Microtubules tune mechanotransduction through NOX2 and TRPV4 to decrease sclerostin abundance in osteocytes. Science Signaling, 10(506), [eaan5748]. https://doi.org/10.1126/scisignal.aan5748