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: 9098448
• 负责人: Meghan Noelle Knight
• 金额: $ 0.69万
• 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 2017-05-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9098448
• 关键词: Address; Affect; Aging; Biological Assay; Bone Growth; Bone Regeneration; Cells; Clinical; Complex; Defect; Development; FDA approved; Family member; Fracture; Functional disorder; GPR4 gene; In Vitro; Integral Membrane Protein; Laboratories; Leucine-Rich Repeat; Ligands; Maintenance; Measures; Mechanics; Menopause; Metabolic; Modality; Modeling; Molecular; Mus; Orphan; Osteoblasts; Osteogenesis; Osteoporosis; Osteoporotic; PTH gene; Pathologic; Pathway interactions; Pattern; Peptides; Play; Population; Prevention; Process; Proteins; Recombinant Proteins; Recombinants; 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; in vivo; inhibitor/antagonist; knock-down; long bone; mineralization; mouse model; novel; novel therapeutics; osteoblast differentiation; osteoporotic bone; 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(申请人提供)：骨质疏松症是一种继发于衰老、更年期、代谢功能障碍和机械负荷降低的骨量减少的临床状况。阐明维持和构建骨量的因素对于开发针对这些破坏性的骨丢失情况的新治疗方法至关重要。一个有希望进一步研究的合成代谢途径是典型的Wnt信号。规范的Wnt信号可以有效地诱导祖细胞分化为成骨细胞。赞助商的实验室最近证实，Wnt共激活因子R-Respondin 2(RSPO2)在体外也可以促进成骨细胞分化。R-Spinins最近被发现通过富含亮氨酸重复序列的G蛋白偶联受体4、5、6(LGR4-6)的跨膜蛋白来传递信号；然而，目前的研究尚不清楚这是否是RSPO2的主要信号机制，尤其是在成骨细胞中。这一提议将决定RSPO2是否通过Wnt信号通路和LGR受体发挥作用。此外，体内成骨细胞中增加Rsp2是否足以增加骨量的翻译问题也将得到解决。首先，将定义在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。规范的Wnt信号激活对RSPO2在成骨细胞中作用的必要性将通过抑制规范的Wnt信号来确定。下一步，将通过敲除受体来研究LGRs对RSPO2在祖细胞中作用的需求。此外，还将研究LGR在骨中的表达模式以及LGR在成骨细胞形成过程中的表达变化。最后，Rspo2将在小鼠的成骨细胞中有条件地过表达，并将评估长骨的骨量、骨形成率和祖细胞的成骨分化能力的变化。此外，该小鼠品系将与TOPGAL小鼠品系杂交，以评估由于Rspo2过表达导致体内Wnt信号激活的变化。这些实验是促进对成骨细胞发生的了解和利用Wnt信号通路设计用于治疗和预防骨质疏松症的合成代谢疗法的关键步骤。