Osteoclast Inhibitory Lectin, an Immune Cell Product That Is Required for Normal Bone Physiology in Vivo

• Published in: The Journal of biological chemistry Vol. 283; no. 45; pp. 30850 - 30860
• Main Authors: Kartsogiannis, Vicky, Sims, Natalie A., Quinn, Julian M.W., Ly, Chi, Cipetić, Mirijana, Poulton, Ingrid J., Walker, Emma C., Saleh, Hasnawati, McGregor, Narelle E., Wallace, Morgan E., Smyth, Mark J., Martin, T. John, Zhou, Hong, Ng, Kong Wah, Gillespie, Matthew T.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 07.11.2008; American Society for Biochemistry and Molecular Biology
• Subjects: Animals; Bone Diseases, Metabolic - blood; Bone Diseases, Metabolic - genetics; Bone Resorption - blood; Bone Resorption - genetics; Calcium - blood; Female; Humans; Lectins, C-Type - genetics; Lectins, C-Type - metabolism; Male; Membrane Proteins - genetics; Membrane Proteins - metabolism; Mice; Mice, Knockout; Molecular Basis of Cell and Developmental Biology; Organ Size - physiology; Osteoclasts - metabolism; Osteogenesis - physiology; Tibia - metabolism
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M801761200

Osteoclast inhibitory lectin (OCIL or clrb) is a member of the natural killer cell C-type lectins that have a described role mostly in autoimmune cell function. OCIL was originally identified as an osteoblast-derived inhibitor of osteoclast formation in vitro. To determine the physiological function(s) of OCIL, we generated ocil-/- mice. These mice appeared healthy and were fertile, with no apparent immune function defect, and phenotypic abnormalities were limited to bone. Histomorphometric analysis revealed a significantly lower tibial trabecular bone volume and trabecular number in the 10- and 16-week-old male ocil-/- mice compared with wild type mice. Furthermore, ocil-/- mice showed reduced bone formation rate in the 10-week-old females and 16-week-old males while Static markers of bone formation showed no significant changes in male or female ocil-/- mice. Examination of bone resorption markers in the long bones of ocil-/- mice indicated a transient increase in osteoclast number per unit bone perimeter. Enhanced osteoclast formation was also observed when either bone marrow or splenic cultures were generated in vitro from ocil-/- mice relative to wild type control cultures. Loss of ocil therefore resulted in osteopenia in adult mice primarily as a result of increased osteoclast formation and/or decreased bone formation. The enhanced osteoclastic activity led to elevated serum calcium levels, which resulted in the suppression of circulating parathyroid hormone in 10-week-old ocil-/- mice compared with wild type control mice. Collectively, our data suggest that OCIL is a physiological negative regulator of bone.