睡眠剥夺通过CLOCK-BRD4通路加重骨质疏松的作用机制研究OA

Objective To explore the effect of sleep deprivation on bromodomain-containing protein 4(BRD4)acetylation in postmenopausal osteoporosis(PMOP).Methods The PMOP rat model was established by bilateral ovari-ectomy(OVX),and then were divided into two groups with 30 rats in each group.The control group were subjected to a 12-hour light/12-hour dark cycle.The experimental group received artificial light at night(LAN)and the additional light was given from zeitgeber time(ZT)13 to ZT 19.Primary cultured osteoblasts were transfected with Flag-BRD4 overex-pression plasmid or circadian locomotor output cycles kaput(CLOCK)interfering plasmid.Co-immunoprecipitation and Western blot assays were performed to detect the interaction between BRD4 and CLOCK.Results Compared with the control group,OVX rats exposed to LAN exhibited shorter bone length[(40.371±0.147)vs.(38.754±0.078)mm],reduced bone mineral density(BMD)[(0.231±0.016)vs.(0.183±0.024)g/cm2]and decreased bone strength[(9.711±0.754)vs.(9.099±0.272)kg](P＜0.01).Western blot results revealed elevated BRD4 protein expression in the bone tissues of LAN-treated rats.In osteoblasts,the lysine residues K165 and K176 of CLOCK promote BRD4 acetylation.Conclusion Sleep deprivation and estrogen deficiency induce the progression of osteoporosis,and targeting CLOCK-regulated BRD4 acetylation may be a new therapeutic target for the prevention and treatment of PMOP.