title: CytokineRegulation and the signaling mechanism of osteoclast inhibitory peptide-1 (OIP-1/hSca) to inhibit osteoclast formation.
abstract: The osteoclast (OCL) is the primary bone resorbing cell. OCL formation and activity is regulated by local factors produced in the bone microenvironment. We recently identified OCL inhibitory peptide-1 (OIP-1/ hSca) as a novel inhibitor of OCL formation and bone resorption that is produced by OCLs. OIP-1 is a glycosylphosphatidyl-inositol (GPI)-linked membrane protein (16 kDa) related to the mouse Ly-6 family of hematopoietic proteins. OIP-1 mRNA is expressed in human OCL precursors, granulocyte-macrophage colony-forming unit (GM-CFU), bone marrow cells, and osteoblast cells. We used cycle-dependent reverse transcriptase-polymerase chain reaction (RT-PCR) analysis, which further demonstrated that interferon-gamma (IFN-gamma) strongly enhanced OIP-1/hSca mRNA expression in bone marrow cells and GM-CFU. Similarly, interleukin (IL)-1beta also enhanced OIP-1 mRNA expression in GM-CFU. To determine the participation of OIP-1 in IFN-gamma inhibition of OCL formation, we tested the capacity of a neutralizing antibody specific to OIP-1 c-peptide to inhibit IFN-gamma's effects on OCL-like cell differentiation of mouse macrophages, RAW 264.7 cells. Anti-OIP-1 c-peptide specific antibody partially neutralized IFN-gamma inhibition of OCL differentiation. Furthermore, OIP-1 inhibited phospho-c-Jun (p-c-Jun) kinase activity in RAW 264.7 cells. However, OIP-1/hSca did not affect NF-kappaB activation in these cells. Western blot analysis further demonstrated that OIP-1 significantly decreased TNF receptor associated factor 2 (TRAF-2) expression in RAW 264.7 cells. However, OIP-1 had no effect on TRAF-6 expression in these cells. These data show that IFN-gamma enhances OIP-1/hSca expression in OCL precursors, GM-CFU, and that OIP-1 inhibits OCL formation through suppression of TRAF-2 and p-c-Jun kinase activity.
authors.affiliation: Department of Medicine/Hematology, University of Texas Health Science Center, San Antonio, Texas, USA.
authors.forename: Masanori
authors.initials: M
authors.lastname: Koide
authors.forename: Hidefumi
authors.initials: H
authors.lastname: Maeda
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Roccisana
authors.forename: Noriaki
authors.initials: N
authors.lastname: Kawanabe
authors.forename: Sakamuri V
authors.initials: SV
authors.lastname: Reddy
mesh_terms: D000074183:ATPases Associated with Diverse Cellular Activities; D048868:Adaptor Proteins, Signal Transducing; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D002460:Cell Line; D016207:Cytokines / Q000502:physiology*; D017931:DNA Primers; D024202:Electrophoretic Mobility Shift Assay; D006801:Humans; D048031:JNK Mitogen-Activated Protein Kinases; D060588:LIM Domain Proteins; D051379:Mice; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D010010:Osteoclasts / Q000166:cytology* / Q000201:enzymology / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex; D011506:Proteins / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction; D047992:TNF Receptor-Associated Factor 2; D014157:Transcription Factors
chemical_list: D048868:Adaptor Proteins, Signal Transducing; D016207:Cytokines; D017931:DNA Primers; D060588:LIM Domain Proteins; C092282:PSMC5 protein, human; D011506:Proteins; D012333:RNA, Messenger; D047992:TNF Receptor-Associated Factor 2; D014157:Transcription Factors; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D046988:Proteasome Endopeptidase Complex; D000074183:ATPases Associated with Diverse Cellular Activities