Rho-A is critical for osteoclast podosome organization, motility, and bone resorption.
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.
Chellaiah
M A
MA
Renal Division, Barnes-Jewish Hospital, Howard Hughes Medical Institute, St. Louis, Missouri 63110, USA.
Soga
N
N
Swanson
S
S
McAllister
S
S
Alvarez
U
U
Wang
D
D
Dowdy
S F
SF
Hruska
K A
KA
D036002:ADP Ribose Transferases / Q000378:metabolism; D000199:Actins / Q000378:metabolism; D019943:Amino Acid Substitution; D000818:Animals; D001862:Bone Resorption; D001905:Botulinum Toxins; D002465:Cell Movement; D002478:Cells, Cultured; D002645:Chickens; D003599:Cytoskeleton / Q000378:metabolism; D005260:Female; D018260:Gelsolin / Q000378:metabolism; D016297:Mutagenesis, Site-Directed; D010010:Osteoclasts / Q000648:ultrastructure*; D053495:Osteopontin; D012795:Sialoglycoproteins / Q000494:pharmacology; D015398:Signal Transduction; D020742:rhoA GTP-Binding Protein / Q000235:genetics / Q000502:physiology*
D000199:Actins; D018260:Gelsolin; D012795:Sialoglycoproteins; D053495:Osteopontin; D036002:ADP Ribose Transferases; C063007:exoenzyme C3, Clostridium botulinum; D001905:Botulinum Toxins; D020742:rhoA GTP-Binding Protein