Co-regulation of circadian clock genes and microRNAs in bone metabolism / 浙江大学学报（英文版）（B辑：生物医学和生物技术）

Mammalian bone is constantly metabolized from the embryonic stage, and the maintenance of bone health depends on the dynamic balance between bone resorption and bone formation, mediated by osteoclasts and osteoblasts. It is widely recognized that circadian clock genes can regulate bone metabolism. In recent years, the regulation of bone metabolism by non-coding RNAs has become a hotspot of research. MicroRNAs can participate in bone catabolism and anabolism by targeting key factors related to bone metabolism, including circadian clock genes. However, research in this field has been conducted only in recent years and the mechanisms involved are not yet well established. Recent studies have focused on how to target circadian clock genes to treat some diseases, such as autoimmune diseases, but few have focused on the co-regulation of circadian clock genes and microRNAs in bone metabolic diseases. Therefore, in this paper we review the progress of research on the co-regulation of bone metabolism by circadian clock genes and microRNAs, aiming to provide new ideas for the prevention and treatment of bone metabolic diseases such as osteoporosis.

Effect of sorafenib on growth and circadian clock gene expression of human hepatocellular carcinoma in nude mice / 中华肝胆外科杂志

Objective To investigate the function of sorafenib on the growth of hepatocellular carcinoma by establishing subcutaneous transplantation tumor model with nude mice.To explore the effect of sorafenib on circadian clock gene expression in hepatoma cells.Methods Mouse tumor model was established by implanting hepatocarcinoma cell (HepG2) subcutaneously in Balb/C nude mice.Sixteen experimental mice were randomly divided into two groups:sorafenib treatment group (n =8) and solvent control group (n =8).The nude mice were treated with sorafenib (100 mg/kg) and DMSO daily by intragastric administration,respectively.The volume of tumors was recorded every 3 days.The expressions level of circadian clock genes (Per1,Per2,Per3,CLOCK,Cry1,Cry2,BMAL1 and CKIε) were detected by real-time polymerase chain reaction (Real-time PCR).The correlations between the size of the xenografts and the expressions of the circadian clock genes were further analyzed.Results Compared with the control group,the tumor size in the sorafenib treatment group were significantly smaller comparing with the control group.Results of Real-time PCR showed that the expression level of Per1,Cry1 and BMAL1 mRNA was remarkably decreased in the treatment group (Per1,P =0.02;Cry1,P =0.002;BMAL1,P =0.035),the differences were statistically significant.Correlation analysis showed that the size of subcutaneous transplantation tumorsin nude mice was negatively correlated with the expressions of Per1,Per2,Cry1 and Cry2 mRNA in control group.While,the size of subcutaneous transplantation tumors was negatively correlated with the expressions of Per2,Per3 and BMAL1 levels in the sorafenib treatment group.Conclusions There is a negative correlation between the expression levels of some biological clock genes and the size of transplantation tumor in nude mice.Sorafenib treatment significantly inhibited the growth of hepatocellular carcinoma in nude mice and down-regulation the expressions of Per1,Cry1 and BMAL1 mRNA in hepatoma cells.

Effect of 1a,25(OH)2 D3 on circadian clock gene expression in cardiac myocytes / 中华实用儿科临床杂志

Objective To explore the effect of 1a,25(OH)2 D3 on circadian clock gene expressions in cardiac myocytes.Methods Cultured cardiac myocytes isolated from 7 -day -old Sprague -Dawley(SD)rats were identified by immunofluorescence.The medium including 1a,25 (OH)2 D3 (final concentrations were 0 nmol/L,1 nmol/L, 10 nmol/L,50 nmol/L and 100 nmol/L)were added to primary myocardial cells to culture for 2 h and then total RNA was extracted.Real -time polymerase chain reaction (RT -PCR)was applied to analyze myocardial cells circadian clock gene (Bmal1,Per2,Rev -erba)transcript levels to determine optimum concentration of 1a,25(OH)2 D3 .Then, the primary myocardial cells cultured for 72 h were divided into 3 groups:the control group was of serum -free culture medium;serum shock group was of DMEMcontaining 50%volume fraction of horse serum cultured 2 h;1a,25(OH)2 D3 treatment group receiving 1a,25 (OH)2 D3 at optimal concentration cultured 2 h.The cells were collected at 7 time points (0 h,4 h,8 h,12 h,16 h,20 h,24 h)and then total RNA was extracted.RT -PCR was applied to analyze circa-dian clock gene (Bmal1,Per2,Rev -erba)transcript levels in the myocardial cells.Results In the presence of 50 nmol/L 1 a,25(OH)2 D3 ,the Bmal1 mRNA expression showed the highest level,but the Per2 and Rev -erba mRNA expression levels were minimum.Compared with the control group,both 1a,25 (OH)2 D3 treatment group and serum shock group caused day -cycle rhythmic oscillation in circadian clock genes(Bmal1,Per2,Rev -erba)in the cardiac myocytes.And the expressions pattern of Bmal1 and Per2 genes were in the opposite phase.While Bmal1 gene expres-sion appeared at peak at 12 h,Per2 gene expression appeared in a trough.Expression of Rev -erba gene trend began to rise at 8 h,and the highest expression level appeared at 12 -16 h.Conclusions 1a,25(OH)2 D3 can affect Bmal1, Per2 and Rev -erba mRNA expressions of circadian clock genes in the cardiac myocytes.

High-fat Intake is Associated with Alteration of Peripheral Circadian Clock Gene Expression

PURPOSE: Recent studies demonstrated disruption of the circadian clock gene is associated with the development of obesity and metabolic syndrome. Obesity is often caused by the high calorie intake, In addition, the chronic stress tends to contribute to the increased risk for obesity. To evaluate the molecular mechanisms, we examined the expression of circadian clock genes in high fat diet-induced mice models with the chronic stress. METHODS: C57BL/6J mice were fed with a 45% or 60% high fat diet for 8 weeks. Daily immobilization stress was applied to mice fed with a 45% high fat for 16 weeks. We compared body weight, food consumption, hormone levels and metabolic variables in blood. mRNA expression levels of metabolic and circadian clock genes in both fat and liver were determined by quantitative RT-PCR. RESULTS: The higher fat content induced more severe hyperglycemia, hyperlipidemia and hyperinsulinemia, and these results correlated with their relevant gene expressions in fat and liver tissues. Chronic stress had only minimal effects on metabolic variables, but it altered the expression patterns of metabolic and circadian clock genes. These results suggest that the fat metabolism regulates the function of the circadian clock genes in peripheral tissues, and stress hormones may contribute to its regulation.

Mechanism research and effects of clock gene Per2 in K562 leukemia cells on their proliferation,differentiation and apoptosis / 第三军医大学学报

Objective To investigate the effects of circadian clock gene Period2(Per2)on the proliferation,differentiation and apoptosis of K562 cells and its probable molecular mechanism.Methods The Per2 expression plasmid pcDNA3.1-Per2 and empty control plasmid were respectively transfected into K562 cells with cationic liposome,and the resistant cells stably expressing Per2 gene were obtained by G418 selection.Their morphological changes were observed under light microscope following Wright-Giemsa staining.Trypan blue excluding staining and MTT assay were employed to evaluate cell proliferation.Flow cytometry was performed to analyze cell cycle distribution and cell apoptosis,and electron microscopy was used to detect cell apoptosis.Meanwhile,the expressions of proliferation and apoptosis associated proteins,such as P53,Cyclin B1 and C-Myc,were respectively detected by RT-PCR and Western blot analysis at mRNA and protein level.Results The K562/Per2 cell line stably expressing Per2 gene was screened out.As compared with either the empty plasmid transfected group(K562/empty)or the untreated group(K562/untreated),K562/Per2 cells was smaller in volume and showed no obvious cellular differentiation.Circadian clock gene Per2 could significantly inhibit both growth and proliferation of K562 cells.The percentage of K562 cells in G2/M phase increased [K562/Per2 group(36.1?5.5)%,K562/empty group(12.5?2.9)%,untreated group(9.7?2.3)%,P