Osteoclast differentiation and function in aquaglyceroporin AQP9-null mice.
BACKGROUND
Osteoclasts are cells specialized for bone resorption and play important roles in bone growth and calcium homoeostasis. Differentiation of osteoclasts involves fusion of bone marrow macrophage mononuclear precursors in response to extracellular signals. A dramatic increase in osteoclast cell volume occurs during osteoclast biogenesis and is believed to be mediated by AQP9 (aquaporin 9), a membrane protein that can rapidly transport water and other small neutral solutes across cell membranes.


RESULTS
In the present study we report an increase in expression of AQP9 during differentiation of a mouse macrophage cell line into osteoclasts. Bone marrow macrophages from wild-type and AQP9-null mice differentiate into osteoclasts that have similar morphology, contain comparable numbers of nuclei, and digest synthetic bone to the same extent. Bones from wild-type and AQP9-null mice contain similar numbers of osteoclasts and have comparable density and structure as measured by X-ray absorptiometry and microcomputed tomography.


CONCLUSIONS
Our results confirm that AQP9 expression rises during osteoclast biogenesis, but indicate that AQP9 is not essential for osteoclast function or differentiation under normal physiological conditions.
Liu
Yangjian
Y
Department of Cell Biology, Duke University Medical Center, Durham, NC 27710, USA.
Song
Linhua
L
Wang
Yiding
Y
Rojek
Aleksandra
A
Nielsen
Søren
S
Agre
Peter
P
Carbrey
Jennifer M
JM
D000818:Animals; D020346:Aquaporins / Q000235:genetics* / Q000378:metabolism*; D001862:Bone Resorption; D001842:Bone and Bones / Q000737:chemistry; D002454:Cell Differentiation; D002460:Cell Line; D005786:Gene Expression Regulation; D051379:Mice; D018345:Mice, Knockout; D010010:Osteoclasts / Q000166:cytology* / Q000187:drug effects / Q000378:metabolism*; D010693:Phloretin / Q000494:pharmacology
C491638:Aqp9 protein, mouse; D020346:Aquaporins; D010693:Phloretin