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Extracellular Calcium (Ca 2+ o )‐Sensing Receptor in a Mouse Monocyte‐Macrophage Cell Line (J774): Potential Mediator of the Actions of Ca 2+ o on the Function of J774 Cells
Author(s) -
Yamaguchi Toru,
Kifor Olga,
Chattopadhyay Naibedya,
Bai Mei,
Brown Edward M.
Publication year - 1998
Publication title -
journal of bone and mineral research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.882
H-Index - 241
eISSN - 1523-4681
pISSN - 0884-0431
DOI - 10.1359/jbmr.1998.13.9.1390
Subject(s) - monocyte , bone resorption , extracellular , cell culture , microbiology and biotechnology , biology , calcium , receptor , resorption , medicine , chemistry , endocrinology , biochemistry , immunology , genetics
The calcium‐sensing receptor (CaR) is a G protein‐coupled receptor that plays key roles in extracellular calcium ion (Ca 2+ o ) homeostasis in parathyroid gland and kidney. Macrophage‐like mononuclear cells appear at sites of osteoclastic bone resorption during bone remodeling and may play a role in the “reversal” phase following osteoclastic resorption and preceding bone formation. Bone resorption produces substantial local increases in Ca 2+ o that could provide a signal for bone marrow mononuclear cells in the vicinity, leading us to investigate whether such mononuclear cells express the CaR. In this study, we used the mouse J774 cell line, which exhibits a pure monocyte‐macrophage phenotype. Both immunocytochemistry and Western blot analysis, using polyclonal antisera specific for the CaR, detected CaR protein in J774 cells. The use of reverse transcriptase‐polymerase chain reaction with CaR‐specific primers, including a set of intron‐spanning primers, followed by nucleotide sequencing of the amplified products, also identified CaR transcripts in J774 cells. Exposure of J774 cells to high Ca 2+ o (2.8 mM or more) or the polycationic CaR agonist, neomycin (100 μM), stimulated both chemotaxis and DNA synthesis in J774 cells. Therefore, taken together, our data strongly suggest that the monocyte‐macrophage cell line, J774, possesses both CaR protein and mRNA very similar, if not identical, to those in parathyroid and kidney.