Effect of Zuoguiwan on Wnt/β-catenin Signaling Pathway in Ovariectomized Osteoporosis Model Rats / 中国实验方剂学杂志

Objective:To observe the effect of Zuoguiwan on bone metabolism and Wnt/<italic>β</italic>-catenin signaling pathway in ovariectomized osteoporotic rats model， and to explore the molecular biological mechanism of Zuoguiwan in the prevention and treatment of osteoporosis. Method:The rat model of postmenopausal osteoporosis was established by bilateral ovariectomy， 60 female SD rats were randomly divided into sham operation group， model group， positive group （estradiol valerate tablet 0.05 mg·kg^-1·d^-1） and low， middle and high dose groups of Zuoguiwan （5.5，11，22 g·kg^-1·d^-1）.After successful establishment of the model in the 13^th week， intragastric administration （<italic>ig</italic>） was given once a day for a total of 12 weeks. After administration， the histomorphological changes of femur in rats were observed by hematoxylin-eosin （HE） staining， the bone mineral density （BMD） and bone mineral content（BMC） of femur were measured by dual energy X-ray apparatus， and the biomechanical properties of bone were measured by MTS Acumen3 biomechanical testing system. The contents of bone alkaline phosphatase （BALP）， bone glaprotein（BGP），estradiol （E₂） ，and tartrate-resistant acid phosphatase （TRAP）， type Ⅰ procollagen N-terminal propeptide （PINP） in serum were detected by enzyme-linked immunosorbent assay （ELISA）. Western blot was used to detect the protein level of Wnt2，<italic>β</italic>-catenin，low density lipoprotein related receptor protein 5 （LRP5） and the phosphorylation level of glycogen synthase kinase-3<italic>β</italic>（GSK-3<italic>β</italic>） in rat tibia. Result:Compared with sham operation group， the maximum load and stiffness of BMD，BMC， in the model group decreased significantly（<italic>P</italic><0.01）， the contents of E₂ and PINP in serum decreased significantly（<italic>P</italic><0.01）， the content of BALP，BGP，TRAP increased significantly（<italic>P</italic><0.01）， the expression levels of Wnt2，p-GSK-3<italic>β </italic>Ser9，LRP5 and <italic>β</italic>-catenin protein in bone tissue decreased significantly（<italic>P</italic><0.01）， the trabecula of femur became thinner and thinner， the number of bone trabeculae decreased. Compared with model group， the maximum load and stiffness of BMD，BMC， in estradiol group and Zuoguiwan group were significantly increased （<italic>P</italic><0.05，<italic>P</italic><0.01）， the contents of serum E₂ and PINP were significantly increased （<italic>P</italic><0.05，<italic>P</italic><0.01）， the content of BALP，BGP，TRAP was significantly decreased （<italic>P</italic><0.01）， and the expression level of Wnt2，p-GSK-3<italic>β</italic> Ser9，LRP5， <italic>β</italic>-catenin protein in bone tissue was significantly increased （<italic>P</italic><0.05，<italic>P</italic><0.01） ， the trabeculae of femur became thicker， the number increased， the structure was basically clear. Conclusion:Zuoguiwan has a certain preventive and therapeutic effect on osteoporosis in ovariectomized rats， and its mechanism may be related to increasing the level of estrogen， activating Wnt/<italic>β</italic>-catenin signaling pathway， up-regulating the expression of Wnt2 and LRP5 protein， inhibiting the activity of GSK-3<italic>β</italic>， reducing the degradation of <italic>β</italic>-catenin， coordinating the dynamic coupling balance between bone formation and bone resorption， correcting the disorder of bone metabolism and improving bone morphology.

One family with osteosclerosis caused by D111Y mutation in the low-density lipoprotein receptor-related protein 5 gene / 中华内分泌代谢杂志

Objective@#To investigate the clinical features and pathogenic genes of a family with osteosclerosis.@*Methods@#Six patients and six family members from a family in Jiangsu were tested for biochemical parameters, bone metabolic markers, bone mineral density, thoracolumbar anterior lateral slices, skull positive lateral radiographs, and pelvic plain films. Meanwhile, Sanger sequencing was performed to detect gene mutations of the proband and five other family members with high bone mass. The conformation of the mutational low-density lipoprotein receptor-related protein 5 (LRP5) protein was predicted by SWISS-MODEL.@*Results@#Four adult patients (one male and three females) were tall, with mandibular enlargement and kyphosis in the center of the lower jaw, and none of the four had fractures. Their X ray examination revealed that the skull and long bone cortex was thickened, while the sella and mandible was enlarged. In addition, the absolute values of bone mineral density at each site of all patients were significantly higher as compared with the standard age- and sex-matched adults or adolescent mean reference values, with Z scores of L2-4, femoral neck and total hip being (6.31±4.03) SD, (6.56±2.36) SD, and (7.19±2.03) SD, respectively. The results of genetic sequencing revealed that all six patients carried a heterozygous mutation (c.331G>T; D111Y) in exon 2 of LRP5 gene, while other family members showed wild type (c.331G>G; D111D). Functional prediction indicated that this mutation was located at the amino acid terminal of exon 2 of LRP5 gene, which encodes the first β-helix-generating region of LRP5 protein.@*Conclusion@#The D111Y mutation in LRP5 gene leads to a clinical phenotype characterized by benign increased bone mineral density without increasing the risk of fracture. This mutation may further affect the downstream Wnt signaling pathway by altering the spatial structure of LRP5 protein, thereby promoting maturation and differentiation of osteoblasts and resulting in osteosclerosis.

Association between Low-density Lipoprotein Receptor-related Protein 5 Polymorphisms and Type 2 Diabetes Mellitus in Han Chinese: a Case-control Study / 生物医学与环境科学（英文）

<p><b>OBJECTIVE</b>To investigate the association between low-density lipoprotein receptor-related protein 5 (LRP5) variants (rs12363572 and rs4930588) and type 2 diabetes mellitus (T2DM) in Han Chinese.</p><p><b>METHODS</b>A total of 1842 T2DM cases (507 newly diagnosed cases and 1335 previously diagnosed cases) and 7777 controls were included in this case-control study. PCR-RFLP was conducted to detect the genotype of the two single nucleotide polymorphisms (SNPs). Odds ratios (ORs) and 95% confidence intervals (95% CIs) were calculated to describe the strength of the association by logistic regression.</p><p><b>RESULTS</b>In the study subjects, neither rs12363572 nor rs4930588 was significantly associated with T2DM, even after adjusting for relevant covariates. When stratified by body mass index (BMI), the two SNPs were also not associated with T2DM. Among the 3 common haplotypes, only haplotype TT was associated with reduced risk of T2DM (OR 0.820, 95% CI 0.732-0.919). In addition, rs12363572 was associated with BMI (P<0.001) and rs4930588 was associated with triglyceride levels (P=0.043) in 507 newly diagnosed T2DM cases but not in healthy controls.</p><p><b>CONCLUSION</b>No LRP5 variant was found to be associated with T2DM in Han Chinese, but haplotype TT was found to be associated with T2DM.</p>

The intervention study of atorvastatin on the effect of proliferation and differentiation and the expression of low density lipoprotein receptor-related protein 5, dickkopf-1 mRNA of osteoblasts caused by low density lipoprotein / 中华内分泌代谢杂志

Objective The aim of this study was to explore the effect of low density lipoprotein ( LDL) on the proliferation and differentiation of MC3T3-E1 osteoblasts, as well as the expression of low density lipoprotein receptor-related protein 5(LRP5) and dickkopf-1(DKK1) mRNA of MC3T3-E1 osteoblasts. The possible mechanisms of the treatment of atorvastatin on LDL expression in MC3T3-E1 osteoblasts were also investigated. Methods Proliferation, osteocalcin expression, LRP5, and expression of DKK1 mRNA of MC3T3-E1 with interaction of LDL at 0. 05, 0. 10, 0. 20 mg/ml levels after 24 h, 48 h, 72 h were detected by CCK8, ELISA, and fluorescence quantitative PCR. Furthermore, proliferation, osteocalcin expression, LRP5 and DKK1 mRNA of MC3T3-E1 after the treatment of atorvastatin of 10-6 mol/L and 10-5 mol/L were also be studied, respectively. Results The effect of LDL on proliferation, expression of osteocalcin and expression of LRP5 and DKK1 mRNA in MC3T3-E1 osteoblasts was the most obvious under LDL with 0. 20 mg/ml level. Under that level, atorvastatin (10-6 mol/L or 10-5 mol/L) was able to make the proliferation of MC3T3-E1 osteoblasts in 48 h and 72 h be decreased, while significantly caused upregulation of osteocalcin, LRP5 mRNA expression; and down regulated DKK1 mRNA expression ( all P<0. 05). Conclusions Atorvastatin can reduce the inhibitory effect of LDL on the proliferation and differentiation of osteoblasts. The mechanisms of atorvastatin on osteoblasts are possibly related to the osteoblast proliferation and expression of LRP5 mRNA and DKK1 mRNA of osteoblasts of wnt signal pathway.

Effects of glycated low density lipoprotein on the proliferation and differentiation and expression of low-density lipoprotein receptor-related protein-5 mRNA, dickkopf-1 mRNA in mouse osteoblasts / 中华内分泌代谢杂志

Objective The aim of this study was to investigate the possible effect of glycated low density lipoprotein ( LDL ) on the proliferation, differentiation, and expression of low-density lipoprotein receptor-related protein5(LRP5)mRNA,dickkopf-1(DKK1)mRNAinmouseosteoblasts(MC3T3-E1cells). WhethertheWnt signaling pathway was involved in the above process was explored else. Methods Mouse MC3T3-E1 cells were culturedwithvariousconcentrationsofglycatedLDL(glycatedLDLlevelwas2.4%,5.3%,8.7%,13.9%)for24, 48, 72 h. Proliferation of MC3T3-E1 cell was measured by CCK-8, the osteocalcin level in the medium was determined by ELISA and the expression of LRP5 mRNA, DKK1 mRNA was measured by realtime PCR. Results After cells being incubated with 5. 3% of glycated LDL for 24 h, the inhibition of MC3T3-E1 cells was more marked than that in control group(P<0. 01). The higher glycated LDL level, the severer the inhibition. The effect of LDL on the MC3T3-E1 cell proliferation was time- and dose-dependent under certain conditions. Osteocalcin level in cell culture fluid with glycated LDL was lowered significantly compared with control group. Meanwhile, the expression of DKK1 mRNA was increased significantly but expression of LRP5 mRNA decreased (P<0. 01) in MC3T3-E1 cells cultured with 5. 3% of glycated LDL for 24 h. Conclusions Proliferation and differentiation of the osteoblasts in mice can be inhibited significantly by glycated LDL. The possible mechanism in the role played by glycated LDL on the proliferation and differentiation in MC3T3-E1 cells seems to be related to expression of LRP5 mRNA, DKK1 mRNA in the Wnt signaling pathway.