Mechanical Control of Smooth Muscle Differentiation During Mouse Lung Branching

项目摘要 由肺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 这些疾病的治疗或在实验室中设计人工肺受到我们的不完整的限制。 了解肺的复杂和定型结构是如何发展的。平滑肌 围绕气道的平滑肌（气道平滑肌，ASM）最近被证明在分叉中起作用 上皮芽的形成，这是肺分支结构发育的重要步骤。以帮助推动 在分化过程中，ASM必须以精确的、 不对称的模式，但控制这种分化的空间格局的机制知之甚少。 信号分子，如音刺猬和骨形态发生蛋白-4，和机械线索，如 已知发育中的气道内的压力增加平滑肌分化。我假设 经骨髓压引起间质中的机械应力分布， 芽尖周围平滑肌分化的空间格局。验证这一假设将支持 模型中，芽尖周围的间充质细胞通过信号传导被引导成为潜在的ASM前体， 分子，但机械应力的精确模式决定了哪些潜在的前体分化成 ASM。为了验证这一假设，我将确定拉伸是否能诱导气道间充质细胞采用 培养物中的ASM表型（Aim 1）。然后，我将分析在高温下培养的肺的RNA测序数据， 和低压力，以了解潜在的分子机制，通过该机制， 转化为形态发生信号（Aim 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尿道压力是否足以 引起间充质中的应力分布，预测芽尖处ASM分化的模式（目的3）。 成功实现这些目标将加深我们对ASM的差异化以及 经肺动脉压影响肺发育。这些知识可以为未来的治疗研究提供信息 调节ASM分化以治疗先天性肺疾病以及指导分化的未来努力 组织工程肺中的平滑肌。

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.