Decoding the mechanical interactions between tissue layers sculpting organ shape

项目摘要/摘要 器官的形状对于正常的功能至关重要。心脏的循环和折叠的畸形， 例如，这是导致人类出生缺陷死亡的主要原因。内脏器官依赖于 多层组织层的协调活动，以折叠和卷曲成目标形状。而社区 对发育过程中控制细胞命运的遗传信号了解很多，但对此了解较少 将基因表达转化为器官形状的机械压力和组织动力学。这 该提案旨在将HOX基因的表达与推动3D多层器官形状变化的物理力量联系起来 以黑腹毛虫中肠为模型系统。 中肠开始是由两个同心组织层组成的管状组织，经历一系列的收缩 折叠成小房间。HOX基因--发育过程中保守的图案主要调节者--有 很早就知道控制这个器官的fiNal形状，但机械应力和组织动力学 将Hox的表达转化为器官的形状仍然难以捉摸。我们最近发现器官收缩 在HOX的控制下，通过外层钙脉冲介导的机械程序进行 基因。光片显微镜的进步现在使整个器官能够在亚细胞中实时可视化 开发过程中的解决方案。将这些成像方法与物理方法相结合提供了一种能力 在整个形态发生过程中跟踪组织层之间的细胞动力学并定量地联系遗传 组织中的图案对组织力学和驱动3D形状变化的动态细胞行为的影响。 提出的工作旨在first(1)解码Hox基因表达模式之间的关系以 中肠钙脉搏的下游模式。(2)其次，物理模型会将钙 脉冲到组织尺度的机械应力，使用钙活动的时空图来限制硅 变形组织的模型。综合起来，这些目标将揭示遗传模式是如何控制机械的 在双层器官中雕刻复杂形状的过程。(3)最后，这项建议将解决中肠如何 模型内脏器官随后在发育过程中卷曲成手性管。“细胞本征”的最新发现 手性，细胞骨架机械打破左右对称性，已被证明在 确定器官尺度的手性。细胞手性转化为3D器官尺度的机械过程 然而，形状的变化在很大程度上仍然是未知的。通过将Intoto成像工具包和分子 在K99阶段掌握的生物学方法，凭借我在博士学位时对手性力学的专业知识，这 AIM将把细胞手性与器官尺度卷曲的动力学联系起来。 总之，这些研究目标以及K99期间的生物学、显微镜和建模方面的培训 阶段将确保我准备好开始一个独立的研究实验室，揭示物理机制 利用生物学来塑造复杂形状的内脏器官。

PROJECT SUMMARY/ABSTRACT Organ shape is vital for proper function. Malformations in the looping and folding of the heart, for instance, represent the leading cause of birth defect mortality in humans. Visceral organs rely on the coordinated activity of multiple laminar tissue layers to fold and coil into targeted shapes. While the community has learned much about the genetic signals governing cell fates during development, less is understood about the mechanical stresses and tissue dynamics that translate gene expression into the shapes of organs. This proposal aims to link hox gene expression to physical forces driving 3D multilayer organ shape change using the D. melanogaster midgut as a model system. The midgut begins as a tube of two concentric tissue layers that undergoes a sequence of constrictions to fold into chambers. Hox genes — conserved master regulators of patterning during development — have long been known to govern the final shape of this organ, but the mechanical stresses and tissue dynamics translating hox expression into organ shape have remained elusive. We recently found that organ constrictions proceed through a mechanical program mediated by calcium pulses in the outer layer, under the control of hox genes. Advances in light-sheet microscopy now enable live visualization of the whole organ at sub-cellular resolution during development. Integrating these imaging methods with physics approaches provides the ability to follow cell dynamics across tissue layers throughout morphogenesis and quantitatively relate genetic patterning in the tissue to the tissue mechanics and dynamic cellular behaviors driving 3D shape change. The proposed work aims to first (1) decode the relationship between the hox gene expression pattern to the downstream pattern of calcium pulses in the midgut. (2) Secondly, a physical model will relate calcium pulses to tissue-scale mechanical stress, using spatiotemporal maps of calcium activity to constrain an in silico model of the morphing tissue. Together, these aims will reveal how genetic patterning controls a mechanical process to sculpt complex shapes in a bilayer organ. (3) Finally, this proposal will address how the midgut model visceral organ coils into a chiral tube later during development. Recent discoveries of `cell intrinsic' chirality, in which cytoskeletal machinery breaks left-right symmetry, have proven to provide a major role in determining organ-scale chirality. The mechanical process by which cell chirality translates into 3D organ-scale shape change, however, remains largely unknown. By combining the in toto imaging toolkit and molecular biology approaches mastered during the K99 phase with my expertise in chiral mechanics from my PhD, this aim will link cellular chirality to the dynamics of organ-scale coiling. Together, these research aims and the training in biology, microscopy, and modeling during the K99 phase will ensure I am equipped to begin an independent research lab revealing the physical mechanisms harnessed by biology to sculpt complex shapes of visceral organs.