Comparison of cellular PTP-oc protein levels in marrow-derived
osteoclasts (A), relative size of TRACP+, multinucleated
osteoclasts (B), responsiveness of marrow osteoclast precursors to
permissive doses of sRANKL in formation of TRACP+, multinucleated
osteoclasts (C), and in vitro bone resorption activity of
osteoclasts (D) of young adult male F2 transgenic mice with
osteoclasts of male WT littermates. A, Western blot of the PTP-oc
protein in two marrow-derived osteoclast cultures of an 8-week-old male
transgenic mouse and that in two osteoclast cultures of an age-matched male WT
littermates. The same blot was blotted against actin for protein loading
control. B, microphotograph of a representative culture of
marrow-derived osteoclasts of a 8-week-old transgenic mouse (right)
and of an age-matched WT littermate (left) are shown. Scale
bar, 20 μm. C summarizes the number of TRACP+, multinucleated
osteoclasts formed from marrow-derived osteoclast precursors (at 1 ×
104 cells/well in 96-well plates) of 7-week-old male transgenic
mice and those of age-matched male WT littermates after 7 days of treatment
with 1, 5, or 10 ng/ml sRANKL and 50 ng/ml m-CSF. Results are shown as mean
± S.E. (n = 6). Statistical significance was analyzed with
two-factor analysis of variance. D summarizes the in vitro
bone resorption activity of the derived osteoclasts from eight male
10-week-old PTP-oc transgenic and eight age-matched male WT
littermates on the resorption pit formation assay. Briefly, the same numbers
of marrow-derived osteoclast precursors were plated on 5-mm dentine slices in
a 48-well plate and were treated with RANKL and m-CSF for 7 days. The cells
were then removed by sonication, and the resorption pits were stained with
acid hematoxylin. The size of more than 50 resorption pits per slice was
measured and divided by the number of pits to get pit area per pit
(osteoclasts). The top shows a representative field of resorption
pits for each test group. Scale bar, 100 μm. The bottom
shows the average pit area per pit (osteoclast) formed (mean ± S.E.,
n = 8 for each group).