CytokineRegulation and the signaling mechanism of osteoclast inhibitory peptide-1 (OIP-1/hSca) to inhibit osteoclast formation.
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.
Koide
Masanori
M
Department of Medicine/Hematology, University of Texas Health Science Center, San Antonio, Texas, USA.
Maeda
Hidefumi
H
Roccisana
Jennifer L
JL
Kawanabe
Noriaki
N
Reddy
Sakamuri V
SV
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
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