title: TRAF family member-associated NF-κB activator (TANK) induced by RANKL negatively regulates osteoclasts survival and function.
abstract: Osteoclasts are the principle bone-resorbing cells. Precise control of balanced osteoclast activity is indispensable for bone homeostasis. Osteoclast activation mediated by RANK-TRAF6 axis has been clearly identified. However, a negative regulation-machinery in osteoclast remains unclear. TRAF family member-associated NF-κB activator (TANK) is induced by about 10 folds during osteoclastogenesis, according to a genome-wide analysis of gene expression before and after osteoclast maturation, and confirmed by western blot and quantitative RT-PCR. Bone marrow macrophages (BMMs) transduced with lentivirus carrying tank-shRNA were induced to form osteoclast in the presence of RANKL and M-CSF. Tank expression was downregulated by 90% by Tank-shRNA, which is confirmed by western blot. Compared with wild-type (WT) cells, osteoclastogenesis of Tank-silenced BMMs was increased, according to tartrate-resistant acid phosphatase (TRAP) stain on day 5 and day 7. Number of bone resorption pits by Tank-silenced osteoclasts was increased by 176% compared with WT cells, as shown by wheat germ agglutinin (WGA) stain and scanning electronic microscope (SEM) analysis. Survival rate of Tank-silenced mature osteoclast is also increased. However, acid production of Tank-knockdown cells was not changed compared with control cells. IκBα phosphorylation is increased in tank-silenced cells, indicating that TANK may negatively regulate NF-κB activity in osteoclast. In conclusion, Tank, whose expression is increased during osteoclastogenesis, inhibits osteoclast formation, activity and survival, by regulating NF-κB activity and c-FLIP expression. Tank enrolls itself in a negative feedback loop in bone resorption. These results may provide means for therapeutic intervention in diseases of excessive bone resorption.
authors.affiliation: Department of Pathology, University of Alabama at Birmingham, Birmingham AL 35294-2182, USA.
authors.forename: Mengrui
authors.initials: M
authors.lastname: Wu
authors.forename: Yiping
authors.initials: Y
authors.lastname: Wang
authors.forename: Lianfu
authors.initials: L
authors.lastname: Deng
authors.forename: Wei
authors.initials: W
authors.lastname: Chen
authors.forename: Yi-Ping
authors.initials: YP
authors.lastname: Li
mesh_terms: D048868:Adaptor Proteins, Signal Transducing / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D000818:Animals; D001862:Bone Resorption; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein / Q000235:genetics / Q000378:metabolism; D002454:Cell Differentiation; D002470:Cell Survival; D025461:Feedback, Physiological; D005786:Gene Expression Regulation; D020868:Gene Silencing; D051379:Mice; D008810:Mice, Inbred C57BL; D010010:Osteoclasts / Q000166:cytology* / Q000378:metabolism; D053245:RANK Ligand / Q000502:physiology*; D034741:RNA, Small Interfering
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D053446:CASP8 and FADD-Like Apoptosis Regulating Protein; C506387:Cflar protein, mouse; D053245:RANK Ligand; D034741:RNA, Small Interfering; C100814:Tank protein, mouse; C505689:Tnfsf11 protein, mouse
keywords: NF-κB; Osteoclast.; RANKL; TANK