R-Spondin-2 modulates Wnt signaling to increase bone mass

R-Spondin-2 调节 Wnt 信号传导以增加骨量

• 批准号: 8879957
• 负责人: Meghan Noelle Knight
• 金额: $ 2.97万
• 依托单位: UNIVERSITY OF PENNSYLVANIA
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-06-01 至 2017-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8879957
• 关键词: Address; Affect; Aging; Biological Assay; Bone Growth; Bone Regeneration; Cells; Clinical; Complex; Defect; Development; FDA approved; Family member; Fracture; Functional disorder; Hormones; In Vitro; Integral Membrane Protein; Laboratories; Leucine-Rich Repeat; Ligands; Maintenance; Measures; Mechanics; Menopause; Metabolic; Modality; Modeling; Molecular; Mus; Orphan; Osteoblasts; Osteogenesis; Osteoporosis; Parathyroid gland; Pathologic; Pathway interactions; Pattern; Peptides; Play; Population; Prevention; Process; Proteins; Recombinant Proteins; Recombinants; Relative (related person); Reporter; Reporter Genes; Research; Risk; Role; Secondary to; Signal Pathway; Signal Transduction; Signaling Molecule; Skeleton; Small Interfering RNA; Staging; Stem cells; Testing; Therapeutic; United States; Western Blotting; bisphosphonate; bone; bone healing; bone loss; bone mass; bone resorbing activity; design; human GPR4 protein; in vivo; inhibitor/antagonist; long bone; mineralization; novel; novel therapeutics; osteoblast differentiation; overexpression; prevent; public health relevance; receptor; research study; response; skeletal

DESCRIPTION (provided by applicant): Osteoporosis is a clinical condition of decreased bone mass secondary to aging, menopause, metabolic dysfunction, and decreased mechanical loading. Elucidating factors that maintain and build bone mass is essential for development of novel treatments for these devastating conditions of bone loss. One promising anabolic pathway to further explore is canonical Wnt signaling. Canonical Wnt signaling potently induces the differentiation of progenitor cells to become bone-forming osteoblasts. The sponsor's laboratory recently demonstrated that the Wnt co-activator R-spondin 2 (RSPO2) can also promote osteoblast differentiation in vitro. R-spondins were recently established to signal through the transmembrane proteins Leucine-rich repeat- containing G-protein coupled Receptors 4, 5, 6 (LGR4-6); however, current research is unclear on whether this is the predominant signaling mechanism for RSPO2, particularly in osteoblasts. This proposal will determine whether RSPO2 operates through the Wnt signaling pathway and LGR receptors. As well, the translational question of whether increasing Rspo2 in osteoblasts in vivo is sufficient to increase bone mass will be addressed. First, changes in Wnt signaling pathway activation relative to RSPO2 levels during osteoblast differentiation will be defined. The necessity of canonical Wnt signaling activit for RSPO2 action in osteoblasts will be determined through inhibition of canonical Wnt signaling. Next, the requirement of LGRs for RSPO2 action in progenitor cells will be investigated by knockdown of the receptors. The expression pattern of LGRs in bone as well as changes in LGR expression during osteoblastogenesis will also be examined. Finally, Rspo2 will be conditionally overexpressed in osteoblasts in mice, and long bones will be evaluated for changes in bone mass, bone formation rate, and osteoblast differentiation capabilities of progenitor cells. Additionally, this mouse line will be crossed with a TOPGAL mouse line to assess changes in Wnt signaling activation in vivo due to Rspo2 overexpression. These experiments are critical steps in advancing the understanding of osteoblastogenesis and in harnessing the Wnt signaling pathway to design anabolic therapeutics for osteoporosis treatment and prevention.

描述（由申请人提供）：骨质疏松症是继发于衰老、更年期、代谢功能障碍和机械负荷减少的骨量减少的临床病症。阐明维持和建立骨量的因素对于开发针对这些破坏性骨质流失病症的新疗法至关重要。一种有希望进一步探索的合成代谢途径是经典 Wnt 信号传导。经典 Wnt 信号传导有效诱导祖细胞分化为骨形成成骨细胞。申办方实验室最近证明，Wnt 共激活剂 R-spondin 2 (RSPO2) 也可以在体外促进成骨细胞分化。最近建立了 R-spondins，通过富含亮氨酸重复序列的跨膜蛋白 G 蛋白偶联受体 4、5、6 (LGR4-6) 发出信号；然而，目前的研究尚不清楚这是否是 RSPO2 的主要信号传导机制，特别是在成骨细胞中。该提案将确定 RSPO2 是否通过 Wnt 信号通路和 LGR 受体发挥作用。此外，增加体内成骨细胞中的 Rspo2 是否足以增加骨量这一转化问题也将得到解决。首先，将定义成骨细胞分化过程中 Wnt 信号通路激活相对于 RSPO2 水平的变化。经典 Wnt 信号传导活性对于成骨细胞中 RSPO2 作用的必要性将通过抑制经典 Wnt 信号传导来确定。接下来，将通过敲低受体来研究祖细胞中 LGR 对 RSPO2 作用的需求。还将检查骨中 LGR 的表达模式以及成骨细胞发生过程中 LGR 表达的变化。最后，Rspo2将在小鼠的成骨细胞中条件性过表达，并评估长骨的骨量、骨形成率和祖细胞的成骨细胞分化能力的变化。此外，该小鼠品系将与 TOPGAL 小鼠品系杂交，以评估由于 Rspo2 过度表达而导致的体内 Wnt 信号激活的变化。这些实验是推进对成骨细胞生成的理解以及利用 Wnt 信号通路设计用于骨质疏松症治疗和预防的合成代谢疗法的关键步骤。