Mechanical Control of Smooth Muscle Differentiation During Mouse Lung Branching

项目摘要 由肺部发育障碍引起的疾病很普遍，而且往往是致命的。我们发展的能力 这些疾病的治疗方法或在实验室中设计人工肺都受到我们不完整的限制 了解肺的复杂和刻板印象结构是如何发展的。这是一块平滑的肌肉 最近发现，呼吸道周围(气道平滑肌，ASM)在分叉中起着重要作用 上皮芽，是肺分支结构发育的重要一步。帮助驾驶 分叉，ASM必须与上皮芽尖周围的间质区分开来 不对称格局，但控制这种空间分化格局的机制还知之甚少。 信号分子，如声波刺猬和骨形态发生蛋白-4，以及机械信号，如 已知的是，发育中的呼吸道内的压力会增加平滑肌的分化。我假设 经肺压力导致间充质中的机械应力分布，该分布指定 芽尖周围平滑肌分化的空间格局。证实这一假设将支持 芽尖周围的间充质细胞通过信号被激活为潜在的ASM前体的模型 分子，但机械应力的精确模式决定了哪些潜在的前体分化为 ASM.为了验证这一假设，我将确定拉伸是否可以诱导呼吸道间充质细胞采用 培养中的ASM表型(目标1)。然后我将分析在高密度下培养的肺的RNA测序数据 和低压，以了解跨肺压的潜在分子机制 转化为形态发生信号(目标2)。最后，我将使用肺体积的计算模型 重建以确定芽上皮几何形状和经肺压力是否足以 导致间质中的应力分布，从而预测芽尖ASM分化的模式(目标3)。 成功实现这些目标将加深我们对ASM如何区分以及如何 经肺压力影响肺发育。这一知识可能会为未来的治疗研究提供信息 调节ASM分化治疗先天性肺疾病及未来指导分化的努力 组织工程肺中的平滑肌肉。

Project Summary Diseases arising from lung developmental disorders are widespread and often deadly. Our abilities to develop therapies for these disorders or to engineer artificial lungs in the laboratory are limited by our incomplete understanding of how the complex and stereotyped architecture of the lung develops. The smooth muscle that surrounds the airways (airway smooth muscle, ASM) has recently been shown to play a role in the bifurcation of epithelial buds, an important step in the development of the branched structure of the lung. To help drive bifurcation, ASM must differentiate from the mesenchyme surrounding epithelial bud tips in a precise and asymmetric pattern, but the mechanisms controlling this spatial pattern of differentiation are poorly understood. Signaling molecules, like sonic hedgehog and bone morphogenic protein-4, and mechanical cues, like the pressure inside the developing airway, are known to increase smooth muscle differentiation. I hypothesize that the transpulmonary pressure causes a distribution of mechanical stress in the mesenchyme that specifies the spatial pattern of smooth muscle differentiation around bud tips. Confirming this hypothesis would support a model in which mesenchymal cells around bud tips are primed to be potential ASM precursors by signaling molecules, but the precise pattern of mechanical stress determines which potential precursors differentiate into ASM. To test the hypothesis, I will determine whether stretch can induce airway mesenchymal cells to adopt an ASM phenotype in culture (Aim 1). I will then analyze RNA sequencing data of lungs cultured under high and low pressure to understand potential molecular mechanisms by which transpulmonary pressure is transduced into a morphogenetic signal (Aim 2). Finally, I will use computational models of lung volumetric reconstructions to determine whether bud epithelial geometry and transpulmonary pressure are sufficient to cause stress distributions in the mesenchyme that predict the pattern of ASM differentiation at bud tips (Aim 3). Successfully completing these aims will deepen our understanding of how ASM differentiates and how transpulmonary pressure affects lung development. This knowledge could inform future research into therapies that modulate ASM differentiation to treat congenital lung diseases and future efforts to direct the differentiation of smooth muscle in tissue-engineered lungs.