Effects of zoledronate on CaMKⅡ δ and down-stream gene expressions during osteoclast differentiation / 重庆医学

ABSTRACT

Objective To study the effect of zoledronate (ZOL) on Ca2+/calmodulin-dependent kinase Ⅱ δ (CaMK Ⅱ δ) and down-stream gene expressions during osteoclast differentiation.Methods Mouse osteoclast precursors RAW264.7 cells were divided into the control group and ZOL group.The cells in both groups were induced with 50μg/L receptor activator of nuclear factor kappa B ligand (RANKL) and were harvested on 5 d,while the cells in ZOL group were also simultaneously treated with 1 × 10-6 mol/L ZOL for 2 d.Five days later,the cells were harvested and examined osteoclastogenesis,as well as gene expressions of CaMK Ⅱ δ,nuclear factor of activated T-cells cytoplasmic 1 (NFATc1),tartrate-resistant acid phosphatase (TRAP) and cell-sarcoma receptor coactivator (c-Src).Results The number of TRAP positive multinuclear osteoclasts,number and size of dentin absorption lacunae and area in the ZOL group were (20.0±3.2),(18.0±4.2) and (6 335.3± 1 043.2)μm2 respectively,which were significantly lower than (36.0 ± 8.4),(37.2 ± 5.0) and (11 636.2 ± 3 661.1) μm2 in the control group and decreased by 44.4 ％,51.6 ％ and 45.6 ％ respectively (P＜0.01).ZOL also significantly inhibited the gene expressions of CaMK Ⅱ δ,NFATc1,TRAP and c-Src,and the mRNA levels of these genes were decreased by 44.1％,49.0％,53.8％ and 49.6％ respectively,the protein level were decreased by 43.5 ％,32.2 ％,45.5 ％ and 48.0 ％ respectively.The immunofluorescent cytochemistry detection results showed the fluorescence intensity of CaMK Ⅱ δ,NFATc1,TRAP and c-Srcin in the ZOL group was significantly weakened when compared with the control group.Conclusion ZOL could significantly inhibit the osteoclast formation and bone absorption function,and down-regulates gene expressions of CaMK Ⅱ δ,NFATc1,TRAP and c-Src in osteoclast differentiation.