Bioelectrical Controls of Morphogenesis

描述（由申请人提供）：脊椎动物身体平面的左-右（LR）不对称性是发育和进化生物学的一个令人着迷的谜题，对生物医学具有深远的影响。侧位缺陷影响超过1 / 6000的足月出生婴儿，分子细节对于理解、检测、预防和修复与侧位模式错误相关的出生缺陷至关重要。该领域目前处于混乱状态，缺乏概念模型，可以将小鼠和斑马鱼胚胎LR模式的机制与在爪蟾中发现的更早的机制联系起来。我们最近的工作已经确定了在早期LR模式中起作用的完全新颖的离子流依赖事件，并且保守于青蛙，小鸡和斑马鱼。然而，现有的模型并不能解释电压梯度如何能够可靠地定向于鸡和哺乳动物的身体平面图中的LR轴。令人兴奋的数据表明，细胞和组织中离子通道和泵依赖电流产生的内源性电压和pH梯度调节了胚胎发育和再生过程中许多重要的形态发生事件。最近大量的研究工作集中在基因转录网络和分泌信号因子上，但在很大程度上忽视了这些引人入胜的表观遗传生物物理现象。我们的实验室结合了分子和细胞生物学、生物物理学、生理学和计算机建模的强大现代工具；因此，我们的工作不仅有助于理解左右模式，而且还揭示了内源性离子流如何控制细胞行为的新分子细节。我们的方法和试剂提供了一个宝贵而独特的机会来解决早期细胞质事件如何在与胚胎中线对齐的大卵裂球中建立不对称，这在其他动物（如哺乳动物）中可能起作用，而许多小细胞存在。我们将通过(1)确定3种特定离子转运体如何通过自主“组织者”的焦点参与将LR不对称性强加到大细胞场中，以及(2)表征极性和细胞骨架蛋白在控制细胞中离子通量的定位和/或行为方面的相互作用，来解决这一难题。总之，这些实验利用了模型系统（爪蟾）中适用于分子遗传学和功能生物物理学的一套强大的方法。通过利用我们已经获得的令人兴奋的初步和已发表的数据，我们的工作将揭示可用于深入了解形态发生的细胞和进化生物学的新机制，将该领域与主流分子发育生物学相结合，并最终作为针对出生缺陷，再生和肿瘤生物学许多领域的新方法的基础。

DESCRIPTION (provided by applicant): The consistent left-right (LR) asymmetry of the vertebrate bodyplan is a fascinating puzzle of developmental and evolutionary biology, and has profound implications for biomedicine. Laterality defects affect more than 1 in 6000 babies born to term, and the molecular details are crucial to understanding, detection, prevention, and repair of birth defects related to errors of LR patterning. The field is currently in disarray, lacking conceptual models that can link mechanisms uncovered for the LR patterning of mouse and zebrafish embryos to the much earlier mechanisms that have been discovered in Xenopus. Our recent work has identified completely novel ion flow-dependent events that function in early LR patterning and are conserved to frog, chick, and zebrafish. However, the existing models do not explain how voltage gradients can be reliably oriented with respect to the LR axis in chick and mammalian body-plans. Exciting data indicate that endogenous voltage and pH gradients produced by ion channel and pump-dependent current flows in cells and tissues regulate a number of important morphogenetic events in embryonic development and regeneration. The recent explosion of work focused on gene transcription networks and secreted signaling factors have largely neglected these fascinating epigenetic biophysical phenomena. Our lab combines the powerful modern tools of molecular and cell biology, biophysics, physiology, and computer modeling; thus, our work will not only contribute to understanding left-right patterning but also reveal new molecular details of how endogenous ion flows control cell behavior. Our approaches and reagents present a valuable and unique opportunity to resolve the major puzzle of how early, cytoplasmic events that set up asymmetry in large blastomeres aligned with the embryo's midline may function in other animals (such as mammals) where many small cells exist instead. We will resolve this puzzle by addressing the major outstanding questions through (1) determining how 3 specific ion transporters are involved in the imposition of LR asymmetry onto large cell fields by foci of autonomous "organizers", and (2) characterizing the interaction of polarity and cytoskeleton proteins in controlling the localization and/or behavior of ion fluxes in cells. Together, these experiments take advantage of a powerful set of approaches in a model system (Xenopus) amenable to both molecular genetics and functional biophysics. By capitalizing on the exciting base of preliminary and published data that we have obtained, our work will reveal novel mechanisms that can be used to gain insight into the cell and evolutionary biology of morphogenesis, will integrate this field with mainstream molecular developmental biology, and will ultimately serve as the basis for novel approaches targeting many areas of birth defects, regeneration, and tumor biology.