title: Chemokine and chemokine receptor expression during colony stimulating factor-1-induced osteoclast differentiation in the toothless osteopetrotic rat: a key role for CCL9 (MIP-1gamma) in osteoclastogenesis in vivo and in vitro.
abstract: Osteoclasts differentiate from hematopoietic precursors under systemic and local controls. Chemokines and receptors direct leukocyte traffic throughout the body and may help regulate site-specific bone resorption. We investigated bone gene expression in vivo during rapid osteoclast differentiation induced by colony-stimulating factor 1 (CSF-1) in Csf1-null toothless (tl/tl) rats. Long-bone RNA from CSF-1-treated tl/tl rats was analyzed by high-density microarray over a time course. TRAP (tartrate-resistant acid phosphatase)-positive osteoclasts appeared on day 2, peaked on day 4, and decreased slightly on day 6, as marrow space was expanding. TRAP and cathepsin K mRNA paralleled the cell counts. We examined all chemokine and receptor mRNAs on the arrays. CCL9 was strongly induced and peaked on day 2, as did its receptor, CCR1, and regulatory receptors c-Fms (CSF-1 receptor) and RANK (receptor activator of nuclear factor kappaB). Other chemokines and receptors showed little or no significant changes. In situ hybridization and immunohistochemistry revealed CCL9 in small, immature osteoclasts on day 2 and in mature cells at later times. Anti-CCL9 antibody inhibited osteoclast differentiation in culture and significantly suppressed the osteoclast response in CSF-1-treated tl/tl rats. While various chemokines have been implicated in osteoclastogenesis in vitro, this first systematic analysis of chemokines and receptors during osteoclast differentiation in vivo highlights the key role of CCL9 in this process.
authors.affiliation: Dept of Cell Biology, University of Massachusetts Medical School, Worcester, MA 01655, USA.
authors.forename: Meiheng
authors.initials: M
authors.lastname: Yang
authors.forename: Geneviève
authors.initials: G
authors.lastname: Mailhot
authors.forename: Carole A
authors.initials: CA
authors.lastname: MacKay
authors.forename: April
authors.initials: A
authors.lastname: Mason-Savas
authors.forename: Justin
authors.initials: J
authors.lastname: Aubin
authors.forename: Paul R
authors.initials: PR
authors.lastname: Odgren
mesh_terms: D000818:Animals; D056657:Cathepsin K; D002403:Cathepsins / Q000235:genetics; D002454:Cell Differentiation / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D019742:Chemokines, CC / Q000235:genetics* / Q000502:physiology*; D020869:Gene Expression Profiling; D006023:Glycoproteins / Q000235:genetics; D016173:Macrophage Colony-Stimulating Factor / Q000494:pharmacology*; D019402:Macrophage Inflammatory Proteins / Q000502:physiology*; D010010:Osteoclasts / Q000166:cytology*; D010022:Osteopetrosis; D053244:Osteoprotegerin; D012313:RNA / Q000032:analysis; D051381:Rats; D011919:Rats, Inbred Strains; D016186:Receptor, Macrophage Colony-Stimulating Factor / Q000235:genetics; D054389:Receptors, CCR1; D019707:Receptors, Chemokine / Q000235:genetics*; D018160:Receptors, Cytoplasmic and Nuclear / Q000235:genetics; D018124:Receptors, Tumor Necrosis Factor / Q000235:genetics
chemical_list: C510551:CCL9 protein, rat; C515302:Ccr1 protein, rat; D019742:Chemokines, CC; D006023:Glycoproteins; D019402:Macrophage Inflammatory Proteins; D053244:Osteoprotegerin; D054389:Receptors, CCR1; D019707:Receptors, Chemokine; D018160:Receptors, Cytoplasmic and Nuclear; D018124:Receptors, Tumor Necrosis Factor; C506032:Tnfrsf11b protein, rat; D012313:RNA; D016173:Macrophage Colony-Stimulating Factor; D016186:Receptor, Macrophage Colony-Stimulating Factor; D002403:Cathepsins; D056657:Cathepsin K; C534133:Ctsk protein, rat