Dmp1 表达细胞中 Twist1 的失活增加骨量,但不影响骨硬化蛋白中和的合成代谢反应。

Twist1 Inactivation in Dmp1-Expressing Cells Increases Bone Mass but Does Not Affect the Anabolic Response to Sclerostin Neutralization.

机构信息

Department of Anatomy & Cell Biology, Indiana University School of Medicine, Indianapolis, IN 46202, USA.

Department of Pediatrics, Indiana University School of Medicine, Indianapolis, IN 46202, USA.

出版信息

Int J Mol Sci. 2019 Sep 9;20(18):4427. doi: 10.3390/ijms20184427.

Abstract

Wnt signaling plays a major role in bone metabolism. Advances in our understanding of secreted regulators of Wnt have yielded several therapeutic targets to stimulate osteoanabolism-the most promising of which is the Wnt inhibitor sclerostin. Sclerostin antibody recently gained approval for clinical use to treat osteoporosis, but the biology surrounding sclerostin antagonism is still incompletely understood. Numerous factors regulate the efficacy of sclerostin inhibition on bone formation, a process known as self-regulation. In previous communications we reported that the basic helix-loop-helix transcription factor Twist1-a gene know to regulate skeletal development-is highly upregulated among the osteocyte cell population in mice treated with sclerostin antibody. In this communication, we tested the hypothesis that preventing Twist1 upregulation by deletion of Twist1 from late-stage osteoblasts and osteocytes would increase the efficacy of sclerostin antibody treatment, since Twist1 is known to restrain osteoblast activity in many models. Twist1-floxed loss-of-function mice were crossed to the Dmp1-Cre driver to delete Twist1 in Dmp1-expressing cells. Conditional Twist1 deletion was associated with a mild but significant increase in bone mass, as assessed by dual energy x-ray absorptiometry (DXA) and microCT (µCT) for many endpoints in both male and female mice. Biomechanical properties of the femur were not affected by conditional mutation of Twist1. Sclerostin antibody improved all bone properties significantly, regardless of Twist1 status, sex, or endpoint examined. No interactions were detected when Twist1 status and antibody treatment were examined together, suggesting that Twist1 upregulation in the osteocyte population is not an endogenous mechanism that restrains the osteoanabolic effect of sclerostin antibody treatment. In summary, Twist1 inhibition in the late-stage osteoblast/osteocyte increases bone mass but does not affect the anabolic response to sclerostin neutralization.

摘要

Wnt 信号在骨骼代谢中起着重要作用。我们对 Wnt 分泌调节剂的理解的进步产生了几个刺激成骨代谢的治疗靶点,其中最有前途的是 Wnt 抑制剂骨硬化素。骨硬化素抗体最近获得了临床使用许可,用于治疗骨质疏松症,但骨硬化素拮抗作用的生物学仍不完全清楚。许多因素调节骨硬化素抑制对骨形成的疗效,这一过程称为自我调节。在之前的交流中,我们报告了基本螺旋-环-螺旋转录因子 Twist1-一种已知调节骨骼发育的基因-在接受骨硬化素抗体治疗的小鼠的破骨细胞中高度上调。在本通讯中,我们测试了这样一个假设,即通过从晚期成骨细胞和破骨细胞中删除 Twist1 来阻止 Twist1 的上调,将增加骨硬化素抗体治疗的疗效,因为 Twist1 已知在许多模型中抑制成骨细胞活性。Twist1-floxed 失活功能小鼠与 Dmp1-Cre 驱动基因杂交,以在 Dmp1 表达细胞中删除 Twist1。条件性 Twist1 缺失与雄性和雌性小鼠的许多终点的双能 X 射线吸收测定法(DXA)和微计算机断层扫描(µCT)评估的骨量轻度但显著增加有关。股骨的生物力学特性不受条件性 Twist1 突变的影响。无论 Twist1 状态、性别或检测的终点如何,骨硬化素抗体都显著改善了所有骨骼特性。当同时检查 Twist1 状态和抗体治疗时,没有发现相互作用,这表明破骨细胞中 Twist1 的上调不是限制骨硬化素抗体治疗成骨作用的内源性机制。总之,晚期成骨细胞/破骨细胞中的 Twist1 抑制增加了骨量,但不影响对骨硬化素中和的合成代谢反应。

https://cdn.ncbi.nlm.nih.gov/pmc/blobs/fe1f/6769567/1f1b96c7477f/ijms-20-04427-g001.jpg

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