Elucidation of the mechanism of glucocorticoid-induced osteoporosis by suppression of Wnt signaling pathway and the development of prediction method at its preclinical stage

我们研究了糖皮质激素对规范的Wnt信号的影响，Wnt信号是促进骨形成的一种新的关键途径。WNT3a增强原代培养人成骨细胞T细胞因子(Tcf)/淋巴增强因子(LEF)依赖的转录活性。地塞米松以剂量依赖的方式抑制这种转录活性，而1，25-二羟基维生素D3增加这种转录活性。糖原合成酶激酶-3β的抑制剂LiCl也能增强Tcf/Lef依赖的转录活性，但地塞米松不能抑制这一作用。抗Dickkopf-1抗体的加入部分恢复了地塞米松抑制的转录活性。地塞米松可减少WNT3a分泌的β-连环素的胞内量，并抑制WNT3诱导的β-连环素的核转位。我们进一步研究了WNT拮抗剂分泌的卷曲相关蛋白1基因是否参与了…用关联性研究进一步了解骨质疏松症的病因。对931名日本妇女进行了SFRP1基因的7个单核苷酸多态(SNPs)基因分型及与骨密度(BMD)的相关性分析。一个SNP(Rs16890444)位于SFRP1基因内含子，另一个(Rs3242)位于SFRP1基因3‘非翻译区，分别与腰椎BMD值和股骨颈及全髋部BMD值显著相关。与C/C或C/T基因携带者相比，携带前一SNP基因T/T基因的女性腰椎骨密度值(L2-L4)较低(根据年龄、绝经时间和体重指数调整后的BMD值)，而携带T/T基因SNP基因的女性股骨颈和全髋部骨密度值高于C/C或C/T基因女性。这些数据表明，糖皮质激素抑制培养的人成骨细胞中典型的WNT信号，部分是通过促进Dickkopf-1的产生，SFRP1可能是BMD决定基因的候选基因。较少

We investigated the effect of glucocorticoid on canonical Wnt signaling that emerged as a novel key pathway for promoting bone formation. Wnt3a increased the T-cell factor (Tcf)/lymphoid enhancer factor (Lef)-dependent transcriptional activity in primary cultured human osteoblasts. Dexamethasone suppressed this transcriptional activity in a dose-dependent manner, while 1,25-dihydroxyvitamin D3 increased this transcriptional activity. LiCl, an inhibitor of glycogen synthase kinase-3beta, also enhanced the Tcf/Lef-dependent transcriptional activity, which was, however, not inhibited by dexamethasone. The addition of anti-dickkopf-1 antibody partially restored the transcriptional activity suppressed by dexamethasone. Dexamethasone decreased the cytosolic amount of beta-catenin accumulated by Wnt3a and also inhibited the nuclear translocation of beta-catenin induced by Wnt3a.We further examine whether the gene of secreted frizzled-related protein 1 (SFRP1), a Wnt antagonist, is involved in … More the etiology of osteoporosis using association study. Seven single nucleotide polymorphisms (SNPs) in the SFRP1 gene were genotyped and analyzed for association with bone mineral density (BMD) in 931 Japanese women. One SNP (rs16890444) located in intron and another (rs3242) located in the 3' untranslated region of the sFRP1 gene were significantly associated with the lumbar spine BMD value, and BMD values for both the femoral neck and the total hip, respectively. Women with the T/T genotype of the former SNP had a lower BMD value of the lumbar spine (L2-L4) compared with those with C/C or C/T (BMD value adjusted for age, duration after menopause, and body mass index, while women with the T/T genotype of the latter SNP had higher BMD values of femoral neck and total hip compared with those with C/C or C/T.These data suggest that glucocorticoid suppresses the canonical Wnt signal in cultured human osteoblasts, partially through the enhancement of the dickkopf-1 production and that the SFRP1 may be a candidate gene for a BMD determinant. Less