Isolation of a human homolog of osteoclast inhibitory lectin that inhibits the formation and function of osteoclasts.
Osteoclast inhibitory lectin (OCIL) is a newly recognized inhibitor of osteoclast formation. We identified a human homolog of OCIL and its gene, determined its regulation in human osteoblast cell lines, and established that it can inhibit murine and human osteoclast formation and resorption. OCIL shows promise as a new antiresorptive.


BACKGROUND
Murine and rat osteoclast inhibitory lectins (mOCIL and rOCIL, respectively) are type II membrane C-type lectins expressed by osteoblasts and other extraskeletal tissues, with the extracellular domain of each, expressed as a recombinant protein, able to inhibit in vitro osteoclast formation.


METHODS
We isolated the human homolog of OCIL (hOCIL) from a human fetal cDNA library that predicts a 191 amino acid type II membrane protein, with the 112 amino acid C-type lectin region in the extracellular domain having 53% identity with the C-type lectin sequences of rOCIL and mOCIL. The extracellular domain of hOCIL was expressed as a soluble recombinant protein in E. coli, and its biological effects were determined.


CONCLUSIONS
The hOCIL gene is 25 kb in length, comprised of five exons, and is a member of a superfamily of natural killer (NK) cell receptors encoded by the NK gene complex located on chromosome 12. Human OCIL mRNA expression is upregulated by interleukin (IL)-1alpha and prostaglandin E2 (PGE2) in a time-dependent manner in human osteogenic sarcoma MG63 cells, but not by dexamethasone or 1,25 dihydroxyvitamin D3. Soluble recombinant hOCIL had biological effects comparable with recombinant mOCIL on human and murine osteoclastogenesis. In addition to its capacity to limit osteoclast formation, OCIL was also able to inhibit bone resorption by mature, giant-cell tumor-derived osteoclasts. Thus, a human homolog of OCIL exists that is highly conserved with mOCIL in its primary amino acid sequence (C-lectin domain), genomic structure, and activity to inhibit osteoclastogenesis.
Hu
Yun Shan
YS
Bone, Joint, and Cancer Unit, St. Vincent's Institute of Medical Research, Fitzroy, Victoria, Australia.
Zhou
Hong
H
Myers
Damian
D
Quinn
Julian M W
JM
Atkins
Gerald J
GJ
Ly
Chi
C
Gange
Christine
C
Kartsogiannis
Vicky
V
Elliott
Jan
J
Kostakis
Panagiota
P
Zannettino
Andrew C W
AC
Cromer
Brett
B
McKinstry
William J
WJ
Findlay
David M
DM
Gillespie
Matthew T
MT
Ng
Kong Wah
KW
D000135:Acid Phosphatase / Q000032:analysis; D000595:Amino Acid Sequence; D000818:Animals; D001854:Bone Marrow Cells / Q000187:drug effects; D001862:Bone Resorption / Q000517:prevention & control; D002117:Calcitriol / Q000494:pharmacology; D002454:Cell Differentiation / Q000187:drug effects; D045744:Cell Line, Tumor; D002478:Cells, Cultured; D004247:DNA / Q000737:chemistry / Q000235:genetics; D003907:Dexamethasone / Q000494:pharmacology; D015232:Dinoprostone / Q000494:pharmacology; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D007375:Interleukin-1 / Q000494:pharmacology; D007527:Isoenzymes / Q000032:analysis; D037181:Lectins, C-Type / Q000235:genetics / Q000502:physiology*; D016173:Macrophage Colony-Stimulating Factor / Q000494:pharmacology; D008565:Membrane Proteins / Q000235:genetics / Q000494:pharmacology; D051379:Mice; D008810:Mice, Inbred C57BL; D008969:Molecular Sequence Data; D010006:Osteoblasts / Q000187:drug effects / Q000502:physiology; D010010:Osteoclasts / Q000166:cytology / Q000187:drug effects / Q000502:physiology*; D016133:Polymerase Chain Reaction; D011956:Receptors, Cell Surface; D011993:Recombinant Fusion Proteins / Q000096:biosynthesis / Q000235:genetics / Q000494:pharmacology; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013234:Stem Cells / Q000187:drug effects; D000071681:Tartrate-Resistant Acid Phosphatase
C400041:CLEC2D protein, human; D007375:Interleukin-1; D007527:Isoenzymes; D037181:Lectins, C-Type; D008565:Membrane Proteins; C429003:Ocil protein, mouse; D011956:Receptors, Cell Surface; D011993:Recombinant Fusion Proteins; D003907:Dexamethasone; D016173:Macrophage Colony-Stimulating Factor; D004247:DNA; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase; D002117:Calcitriol; D015232:Dinoprostone