Fig. 1: Padi2 knockout mice exhibited reduced bone mass.

A Physiognomy of Padi2 control (Cont), hetero (Het), and knockout (KO) litters at newborn and P7 (n = 4–6 in each group). B Representative micro-CT images of the distal femur at 4 months in the arterial view of a coronal section and cross-sectional views are shown for each genotype (scale bar:1 mm). C Histomorphometric analyses of 3D micro-CT data of control and Padi2 KO mice in both male (n = 9, Cont mice and n = 7, Padi2 KO mice) and female (n = 11, Cont mice and n = 12, Padi2 KO mice). BV/TV bone volume/tissue volume; Tb. Th trabecular thickness; Tb. N trabecular number; Tb. Sp trabecular separation. D, E Representative images of H&E stained distal femur and proximal tibiae from 4 months-aged control and Padi2 KO mice (scale bar: 500 μm, 200μm). F, G Representative images of immunohistochemistry (IHC) for PADI2 (F) and type 1 collagen (COL1) at 4 months-aged Cont and KO mice (G) (scale bar: 500 μm, 200 μm). H Representative images of TRAP-stained trabecular bone of distal femur from 4 months-aged Cont and KO mice. TRAP-positive purple spots indicate multinucleated osteoclasts (scale bar: 500 μm, 200 μm); We performed two or three independent experiments with three biological replicates for each group (D–H). I Osteoclast identification by TRAP staining. Bone marrow-derived macrophages (BMMs) isolated from Cont and KO mice were differentiated into osteoclasts in the presence of CSF1 (20 ng/ml) and RANKL (100 ng/ml) for 5 days (scale bar: 10 μm). The graph shows the number of TRAP-positive osteoclasts with more than three nuclei (n = 8 in each group). Three independent experiments with eight biological replicates for each group. Data are expressed as the mean ± SE. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001. N.S, not significant.