Document Detail


Involvement of aquaporin 9 in osteoclast differentiation.
MedLine Citation:
PMID:  16698796     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
Aquaporins (water channels) selectively enhance water permeability of membranes. Since osteoclast differentiation includes a dramatic increase in cell volume, we hypothesize that aquaporin(s) is/are critical for the formation of the multinucleated osteoclast from its mononuclear precursor. Our studies employ two cell models, bone marrow macrophages (BMMs) and the murine macrophage-like cell line, RAW264.7, as osteoclast precursors. Receptor activator of nuclear factor kappaB (NF-kappaB) ligand (RANKL) and macrophage-colony-stimulating factor or RANKL alone were used to induce osteoclast differentiation in BMMs or RAW264.7 cells, respectively. We first used qualitative reverse transcription (RT)-PCR to examine which of the aquaporins are expressed in osteoclasts and in their precursor cells. Out of the 10 aquaporins examined, only aquaporin 9 (AQP9) was expressed in osteoclast-lineage cells. AQP9 has unique aqueous pore properties mediating the passage of a wide variety of non-charged solutes in addition to water. Western analyses using specific antibodies revealed a higher AQP9 level in RANKL-treated than in untreated cells. Quantitative real-time RT-PCR analyses also demonstrated higher AQP9 mRNA levels in RANKL-treated cells. Finally, we examined the effect of phloretin, an AQP9 inhibitor, on RANKL-induced osteoclast differentiation. Cells were incubated with RANKL for 5 days, and phloretin was added for the last 2 days, when most fusion occurs. A dramatic reduction in osteoclast size and in the number of nuclei per osteoclast was observed in cultures containing phloretin. The inhibitor did not have a significant effect on the number and size of mononuclear phagocytes in cultures not treated with RANKL. Our results suggest a role for AQP9 in osteoclast differentiation, specifically in the fusion process.
Authors:
Refael Aharon; Zvi Bar-Shavit
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Publication Detail:
Type:  Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't     Date:  2006-05-12
Journal Detail:
Title:  The Journal of biological chemistry     Volume:  281     ISSN:  0021-9258     ISO Abbreviation:  J. Biol. Chem.     Publication Date:  2006 Jul 
Date Detail:
Created Date:  2006-07-10     Completed Date:  2006-08-21     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  2985121R     Medline TA:  J Biol Chem     Country:  United States    
Other Details:
Languages:  eng     Pagination:  19305-9     Citation Subset:  IM    
Affiliation:
Humphrey Center for Experimental Medicine and Cancer Research, The Hebrew University Faculty of Medicine, Jerusalem 91120, Israel.
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MeSH Terms
Descriptor/Qualifier:
Animals
Aquaporins / metabolism,  physiology*
Bone Marrow Cells / cytology
Carrier Proteins / metabolism
Cell Differentiation
Cell Line
Cells, Cultured
Macrophages / metabolism
Membrane Glycoproteins / metabolism
Mice
Mice, Inbred BALB C
Osteoclasts / metabolism
Phagocytes / metabolism
Phloretin / pharmacology
RANK Ligand
Receptor Activator of Nuclear Factor-kappa B
Grant Support
ID/Acronym/Agency:
P01 AR48818/AR/NIAMS NIH HHS
Chemical
Reg. No./Substance:
0/Aqp9 protein, mouse; 0/Aquaporins; 0/Carrier Proteins; 0/Membrane Glycoproteins; 0/RANK Ligand; 0/Receptor Activator of Nuclear Factor-kappa B; 0/Tnfrsf11a protein, mouse; 0/Tnfsf11 protein, mouse; 60-82-2/Phloretin

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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