Mechanical regulation of cytoskeleton guides beta-catenin effect on MSC fate

细胞骨架的机械调节引导β-连环蛋白对MSC命运的影响

基本信息

批准号：
9252230
负责人：
Janet E Rubin
金额：
$ 33.44万
依托单位：
UNIV OF NORTH CAROLINA CHAPEL HILL
依托单位国家：
美国
项目类别：
财政年份：
2015
资助国家：
美国
起止时间：
2015-04-01 至 2020-03-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/9252230
关键词：
AKT inhibition Actins Adhesions Adipocytes Adipose tissue Adult Bone Formation Stimulation Bone Marrow Cell Lineage Cell Nucleus Cells Complex Cytoskeletal Modeling Cytoskeleton Data Exercise F-Actin Fatty acid glycerol esters Focal Adhesions Goals Grant Health Histologic In Vitro Knock-out Knockout Mice Lamins Marrow Measures Mechanics Mesenchymal Stem Cells Methods Mus Nuclear Obesity Osteogenesis Pathway interactions Periodicity Pharmacology Phosphotransferases Physicians Physiological Population Proteins Recruitment Activity Regulation Regulatory Pathway Resistance Role Running Scientist Signal Pathway Signal Transduction Stem cells Stress Fibers Structure Tamoxifen Testing Time Work base beta catenin bone bone cell bone fragility bone health bone strength improved in vivo innovation lipid biosynthesis mechanical force mechanical load mouse model osteogenic osteoprogenitor cell prevent public health relevance response sedentary skeletal synergism trafficking

项目摘要

DESCRIPTION (provided by applicant): Exercise builds skeletal strength by inducing new bone formation, which is accompanied by decreased marrow adipose tissue (MAT). A lack of exercise enhances MSC adipogenesis, and increased MAT has been shown to be associated with bone fragility. Understanding mechanisms by which exercise regulates mdMSC lineage allocation to increase osteogenesis and decrease adipogenesis is thus significant for managing skeletal health in an increasingly sedentary population. We have shown that mechanical activation and nuclear trafficking of ßcatenin prevents adipogenesis and promotes MSC entry into osteoprogenitor lineage. ßcatenin signaling is initiated by recruitment of Fyn kinase to foca adhesions during strain, followed by Fyn activation of the mTORC2->Akt->GSK3ß inhibition cascade leading to increased ßcatenin. ßcatenin effects depend on cellular context: in mdMSC, increased cytoskeletal structure improves osteogenesis and cytoskeletal deficiency promotes adipogenesis. The Fyn/mTORC2 proximal signal also activates RhoA to build complexity and connectivity of the cytoskeleton. We propose that mechanically induced cytoskeletal reorganization promotes nuclear entry of ßcatenin, underwriting its anti-adipogenic, pro-osteogenic effect. Importantly, the role of focal adhesion-based Fyn in initiating ßcatenin and RhoA effectors may be unique to the mdMSC, potentially providing a specific pharmacologic target to enhance MSC response to exercise. To test this, we will delineate the synergistic contributions of Fyn/mTORC2's two downstream effectors, RhoA and ßcatenin, to MSC lineage fate allocation in vitro and in vivo. We will find if RhoA generated cytoskeletal reorganization is necessary or sufficient to alter mdMSC cell fate and define how mechanical load activates RhoA (SA1). In SA2, we ask if activation of ßcatenin can alter cell fate in the face of cytoskeletal deficiency, inquiring whether the cytoskeleton drives nuclear/cytoplasmic partitioning of ßcatenin and considering if the actin-nesprin-LINC-nuclear tether might guide ßcatenin into the nucleus. In SA3, using an innovative method to quantify and localize MAT, combined with measures of bone formation, we will investigate mechanical control of mdMSC lineage in vivo, asking if the Fyn/mTORC2 signaling unique to mdMSC is critical during exercise stimulation of bone formation; for this we will generate a Tamoxifen driven Prx1-Cre knock out of Fyn.

描述（由适用提供）：运动通过诱导的新骨形成来建立骨骼强度，这是通过减少骨髓脂肪组织（MAT）来完成的。缺乏运动增强的MSC脂肪形成和增加的MAT已被证明与骨骼脆弱性有关。因此，了解运动调节MDMSC谱系分配以增加成骨和脂肪形成的机制对于管理日益久坐的人群的骨骼健康而言是重要的。我们已经表明，βCatenin的机械激活和核运输可防止脂肪形成，并促进MSC进入骨基源谱系。 βCatenin信号是通过在菌株期间募集FYN激酶向焦点粘附的，然后进行FYN激活MTORC2-> akt->gsk3ß抑制级联反应，从而导致βCatenin增加。 βCatenin的作用取决于细胞环境：在MDMSC中，增加的细胞骨架结构可改善成骨和骨骼缺乏症可促进脂肪形成。 FYN/MTORC2近端信号还激活了RhoA以建立细胞骨架的复杂性和连通性。我们提出机械诱导的细胞骨架重组会促进βCatenin的核进入，从而承受其抗抑制性的促肌稳定作用。重要的是，基于焦点粘合剂Fyn在βCatenin和RhoA效应中的作用可能是MDMSC所独有的，它可能提供了特定的药物靶标，以增强MSC对运动的反应。为了测试这一点，我们将描述FYN/MTORC2的两个下游效应RhoA和βCatenin对MSC谱系命运分配的体外和体内的协同贡献。我们会发现RhoA是否产生的细胞骨架重组是需要或足够的时间来改变MDMSC细胞命运并定义机械载荷如何激活RhoA（SA1）。在SA2中，我们询问βCatenin的激活是否可以在细胞骨架缺乏的情况下改变细胞命运，询问细胞骨架是否驱动βCatenin的核/细胞质分配。并考虑到肌动蛋白 - 涅斯普林 - 核核系绳是否可能引导βCatenin进入核。在SA3中，使用创新的方法来量化和定位垫子，结合骨形成的测量，我们将研究体内MDMSC谱系的机械控制，询问MDMSC在骨形成刺激的运动过程中MDMSC所特有的FYN/MTORC2信号传导是否至关重要；为此，我们将产生一个他莫昔芬驱动Prx1-cre敲出Fyn。