title: Dominant negative MCP-1 blocks human osteoclast differentiation.
abstract: Human osteoclasts were differentiated using receptor activator of NFκB ligand (RANKL) and macrophage colony stimulating factor (M-CSF) from colony forming unit-granulocyte macrophage (CFU-GM) precursors of the myeloid lineage grown from umbilical cord blood. Gene expression profiling using quantitative polymerase chain reaction (Q-PCR) showed more than 1,000-fold induction of chemokine MCP-1 within 24 h of RANKL treatment. MCP-1 mRNA content exceeds that of other assayed chemokines (CCL1, 3, 4, and 5) at all time points up to day 14 of treatment. MCP-1 induction preceded peak induction of calcium signaling activator calmodulin 1 (CALM1) and transcription factors JUN and FOS, which were at 3 days. Key osteoclast related transcription factors NFATc1 and NFATc2 showed peak induction at 7 days, while marker genes for osteoclast function cathepsin K and tartrate resistance acid phosphatase (TRAP) were maximally induced at 14 days, corresponding with mature osteoclast function. To test whether the early and substantial peak in MCP-1 expression is part of human osteoclast differentiation events, a dominant negative inhibitor of MCP-1 (7ND) was added simultaneously with RANKL and M-CSF, resulting in blockade of CALM1, JUN and NFATc2 induction and strong inhibition of human osteoclast differentiation. These data show that a cascade of gene expression leading to osteoclast differentiation depends on intact early MCP-1 induction and signaling in human osteoclasts.
authors.affiliation: School of Medical Science, Griffith University Gold Coast Campus, Parklands Drive, Southport, Queensland, 4215, Australia.
authors.forename: Nigel A
authors.initials: NA
authors.lastname: Morrison
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Day
authors.forename: Geoff C
authors.initials: GC
authors.lastname: Nicholson
mesh_terms: D002147:Calmodulin / Q000096:biosynthesis; D002454:Cell Differentiation / Q000235:genetics*; D002478:Cells, Cultured; D018932:Chemokine CCL2 / Q000235:genetics / Q000378:metabolism*; D020869:Gene Expression Profiling; D018507:Gene Expression Regulation, Developmental; D006801:Humans; D010010:Osteoclasts / Q000166:cytology*; D053245:RANK Ligand / Q000235:genetics; D015398:Signal Transduction / Q000235:genetics*; D014470:Umbilical Cord / Q000166:cytology
chemical_list: C111835:CCL2 protein, human; D002147:Calmodulin; D018932:Chemokine CCL2; D053245:RANK Ligand; C505688:TNFSF11 protein, human
keywords: 7ND; CALMODULIN; CFU-GM; CHEMOKINE MCP-1 NFAT; HUMAN OSTEOCLAST; INHIBITION; JUN; MYELOID