Figure 2.

Osteoclastogenesis, bone resorption and RANKL production are increased in Tgm2^−/−;F13a1^−/− mice. (a) Analysis of the bone resorption marker (serum COL I telopeptide fragments) (RatLaps^TM) shows a significant increase in Tgm2^−/−;F13a1^−/− mice up to 6 months age compared with WT mice. n=5–7. (b) Serum osteocalcin levels are elevated in 3-month-old Tgm2^−/−;F13a1^−/− mice compared with WT mice of same age. n=6. (c) The presence of osteoclasts was increased in lumbar trabecular bone (Tb) in 3-month-old Tgm2^−/−;F13a1^−/− mice compared with WT controls as evident by tartrate-resistant acid phosphatase (TRAP, pink) staining of histology sections (counterstained with hematoxylin). BM; bone marrow. Images are representative of six mice. (d) Quantification of osteoclast numbers relative to trabecular area (N.Oc./T.Ar) shows a significant, twofold increase in 3-month-old mice Tgm2^−/−;F13a1^−/− mice. (e and f) Analysis of the serum RANKL levels and RANKL/OPG ratio shows twofold increase in RANKL production and significant skewing towards RANKL dominance in 3-month-old mice Tgm2^−/−;F13a1^−/− mice. n=6. P-values are as follows: *P<0.05, ** P<0.01, ***P<0.001. Scale bar, 40 μm