Related Experiment Video
Updated: Aug 9, 2026

A RANKL-based Osteoclast Culture Assay of Mouse Bone Marrow to Investigate the Role of mTORC1 in Osteoclast Formation
Published on: March 15, 2018
Rho-A is critical for osteoclast podosome organization, motility, and bone resorption
M A Chellaiah1, N Soga, S Swanson
1Renal Division, Barnes-Jewish Hospital, Howard Hughes Medical Institute, St. Louis, Missouri 63110, USA.
Abstract:
Rho plays a regulatory role in the formation of actin stress fibers and focal adhesions, and it is also involved in integrin-mediated signaling events. To study the role of Rho in alpha(v)beta(3)/gelsolin-dependent signaling, the HIV-Tat peptide, hemagglutinin (HA)-tagged Rho(Val-14) (constitutively active) and Rho(Asn-19) (dominant negative) were transduced into avian osteoclasts. Protein transduction by HA-Tat was highly efficient, and 90-100% of the cells were transduced with HA-tagged proteins. We demonstrate here that Rho(Val-14) transduction (100 nM) stimulated gelsolin-associated phosphatidylinositol 3-kinase activity, podosome assembly, stress fiber formation, osteoclast motility, and bone resorption, mimicking osteoclast stimulation by osteopontin/alpha(v)beta(3.) The effects of Rho(Val-14) transduction stimulation was time-dependent. C3 exoenzyme blocked the effects of Rho(Val-14) and induced podosome disassembly, loss of motility, and inhibition of bone resorption. Transduction of Rho(Asn-19) produced podosome disassembly, and blocked osteopontin stimulation. These data demonstrate that integrin-dependent activation of phosphoinositide synthesis, actin stress fiber formation, podosome reorganization for osteoclast motility, and bone resorption require Rho stimulation.
Related Concept Videos
Bone Remodeling
Rab Proteins
Rab proteins switch between a cytosolic, GDP-bound inactive state and a membrane-anchored, GTP-bound active state. By themselves, Rabs show slow rates of GDP/GTP exchange and GTP hydrolysis. Thus, Rab proteins are considered...
Cell Polarization by Rho Proteins
Osteoclasts in Bone Remodeling
Small GTPases - Ras and Rho
Three regulatory proteins control their activity:
Hormones and Bone Tissue
Hormones That Influence Osteoblasts and/or Maintain the Matrix
Several hormones are necessary for controlling bone growth and maintaining the bone matrix. The pituitary gland secretes growth hormone (GH), which, as its name implies, controls bone growth. This happens in several ways: first, it triggers chondrocyte...

