Mechanical Control of Mesenchymal Stem Cell Lineage Allocation

间充质干细胞谱系分配的机械控制

• 批准号: 8067137
• 负责人: Janet E Rubin
• 金额: $ 28.77万
• 依托单位: UNIV OF NORTH CAROLINA CHAPEL HILL
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-05-01 至 2015-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8067137
• 关键词: Adipocytes; Affect; Aging; Applications Grants; Bed rest; Binding; Bone Marrow; CCAAT-Enhancer-Binding Proteins; Cell Lineage; Cells; Consensus; Data; Disinhibition; Environment; Estrogens; Event; Evolution; Exercise; Fatty acid glycerol esters; Food; Functional disorder; Goals; Grant; Health; Individual; Intracellular Accumulation of Lipids; Investigation; Laboratories; Link; Lipids; Locomotion; Marrow; Mechanical Stimulation; Mechanics; Mesenchymal Stem Cells; Morphology; Mus; Muscle Cells; Nature; Nuclear; Osteoblasts; Osteogenesis; Output; Pathologic; Pathway interactions; Peroxisome Proliferator-Activated Receptors; Phenotype; Phosphorylation; Production; Proteins; Proto-Oncogene Proteins c-akt; Regimen; Regulation; Reporter; Repression; Resistance; Signal Transduction; Skeleton; Source; Stimulus; TSC2 gene; Testing; Time; Transactivation; Work; adipokines; adiponectin; aged; aging population; bone; bone mass; human FRAP1 protein; insight; integrin-linked kinase; lipid biosynthesis; osteogenic; osteoprogenitor cell; prevent; progenitor; public health relevance; receptor; response; sedentary; senescence; skeletal; stem cell differentiation; transcription factor

DESCRIPTION (provided by applicant): Mesenchymal stem cells (MSCs) in bone marrow provide progenitors for both adipocyte and osteoblast cells and the output of the MSC pool reflects a reciprocal relationship between these two lineages. The ability of mechanical signals to promote osteogenic lineage has raised the exciting possibility that exercise might be able to regulate MSC lineage. Our work indicates that mechanical input can inhibit adipogenesis, exerting a significant control over MSC reciprocity through control of ¿-catenin signaling. Signals which promote MSC adipogenesis involve diminution in ¿-catenin signaling, followed by a rise in PPAR?, adiponectin and lipid content. We have compelling data showing that mechanical strain induces persistent ¿-catenin activation in MSC through alteration of GSK3¿ phosphorylation via AKT in MSCs. Repetitive loading bouts increase the ¿-catenin signal duration such that downstream events such as the rise in adiponectin and lipid droplets are inhibited. Our results suggest that even a strongly adipogenic microenvironment can be counteracted in this way by repetitive bouts of mechanical input. This allows us to hypothesize that "mechanical stimulation represses adipogenic conversion through ¿-catenin inhibition of PPAR? action". With this grant proposal we propose to test this hypothesis, fully characterizing the mechanisms by which mechanical input prevents adipogenesis and controls MSC lineage selection. We will investigate the temporal nature of the signal: how much and how many repetitions are required to regulate adipogenesis, and we will ask if mechanical input induces an alternate lineage selection, e.g., osteoprogenitor or myocyte with the help of unique reporter mice from which we make MSC clones for study. Interactions between local cells will be probed asking whether soluble factors secreted from strained cells can act on unstrained cells (SA1). We will ascertain the mechanisms by which mechanical strain activates ¿-catenin (via AKT and GSK32), as well consider other mechanical targets (Wnts and BMPs) that could exert local control. We will consider alternative targets of GSK3¿ such as NFATc1 and mTOR (SA2). We will define how mechanical activation perturbs PPAR? promotion of adipogenesis directly and indirectly in SA3. Our proposal has significance for understanding the fate of MSC in a sedentary and aging population. It will be critically important to characterize the cascade of signals involved in mechanical regulation of MSC lineage selection, as this should identify modifiable steps in pathways that suppress adipogenesis and stimulate osteogenesis. PUBLIC HEALTH RELEVANCE: Evolution has led to interrelationships between bone and fat together to allow individuals to move to food sources (skeleton necessary for locomotion), and store energy (as fat). Clearly our nation's health is impacted by counterproductive "activities" -lack of exercise and caloric excess. Indeed, as the presence of mechanical information prevents emergence of adipocytes from the marrow, exercise may be considered a way to prevent bone marrow senescence as "old" bone marrow mimics unloading with increased fat. As such, understanding the mechanisms by which mechanical input controls lineage selection is highly relevant to an aging population, and should have high importance for understanding the pathophysiology behind the decreased osteoprogenitor pool and how to reverse it. Consensus building now needs to be a targeted goal, examining the basics of how exercise impacts these relationships by defining the fate of mesenchymal stem cells. We propose here a focused investigation of how loading cells can affect lineage selection when that lineage is already directed toward fat (as would be seen in non-exercising individuals, or aged individuals). We seek insights into the type of mechanical input (how much and for how long), and the targets, beginning with ¿-catenin, but considering other factors which determine lineage selection, and what strained cells become. We will examine proximal nodes in strain activation of ¿-catenin and investigate alternative effectors of mechanical strain. We will look at direct effects to prevent adipogenesis (inhibition of PPAR? expression) and indirect ¿- catenin inhibition of PPAR? responses.

描述（由适用提供）：骨髓中的间充质干细胞（MSC）为脂肪细胞和成骨细胞提供了祖细胞，MSC池的输出反映了这两个谱系之间的相互关系。机械信号促进成骨谱系的能力提高了运动可能能够调节MSC谱系的令人兴奋的可能性。我们的工作表明，机械输入可以抑制脂肪形成，通过控制»帕宁蛋白信号传导对MSC互惠产生重大控制。促进MSC脂肪形成的信号涉及在� -Catenin信号传导中的扩散，然后PPAR？，脂联素和脂质含量增加。我们有令人信服的数据，表明机械应变通过MSC中的Akt改变GSK3磷酸化，从而诱导MSC中的持续性� -Catenin激活。重复的载荷发作会增加 - 循环的信号持续时间，因此抑制了下游事件，例如脂联素和脂质液滴的升高。我们的结果表明，即使是强烈的成生成微环境，也可以通过这种方式来抵消机械输入的反弹。这使我们能够假设“机械刺激反映了通过对PPAR的抑制作用？通过这项赠款建议，我们建议检验这一假设，充分表征机械输入阻止脂肪形成并控制MSC谱系选择的机制。我们将研究信号的暂时性：调节脂肪形成需要多少重复，我们将询问机械输入是否会诱导替代的谱系选择，例如，在独特的记者小鼠的帮助下，从而使MSC Clone进行研究。将探测局部细胞之间的相互作用，询问滤伤细胞分泌的固体因子是否可以作用于未培养的细胞（SA1）。我们将确定机械应变激活-Catenin（通过AKT和GSK32）的机制，并考虑其他可能发挥局部控制的机械目标（WNT和BMP）。我们将考虑GSK3的替代目标，例如NFATC1和MTOR（SA2）。我们将定义机械激活如何播放PPAR？在SA3中直接和间接地促进脂肪形成。我们的建议对于理解久坐和衰老的人口中MSC的命运具有重要意义。表征参与MSC谱系选择机械调节的信号的级联对于抑制脂肪形成和刺激成骨的途径中的可修改步骤，这将非常重要。 公共卫生相关性：进化导致骨骼和脂肪之间的相互关系，使个人能够转移到食物来源（运动所需的骨骼），并储存能量（如脂肪）。显然，我们国家的健康受到适得其反的“活动”的影响 - 锻炼和热量过剩。确实，由于机械信息的存在阻止了骨髓中脂肪细胞的出现，因此可以将运动视为一种防止骨髓感应的方法，因为“旧”骨髓模仿脂肪随着脂肪的增加而卸载。因此，理解机械输入控制谱系选择的机制与老龄化的人群高度相关，并且对于理解衰减的骨基因生殖器池背后的病理生理学以及如何逆转它应该具有很高的重要性。现在，建立共识的建设必须是一个目标目标，可以通过定义间充质干细胞的脂肪来研究运动如何影响这些关系的基础。我们在这里提出，当谱系已经针对脂肪时（在非行使的个体或老年人）时，对载荷细胞如何影响谱系选择的重点研究。我们寻求有关机械输入的类型（多少时间和时间）和目标，始于� -Catenin，但考虑了决定谱系选择的其他因素，以及哪些细胞变成了损坏的细胞。我们将检查 - 帕宁蛋白的应变激活中的近端淋巴结，并研究机械应变的替代作用。我们将研究以防止脂肪形成（抑制PPAR？表达）和间接» - Catenin抑制PPAR的直接作用？回答。