Revealing the mechanisms of neural-mediated cardiac proliferation in Ciona robusta

项目总结/摘要 心肌细胞分裂的调节是心脏正常发育所必需的，并且与先天性心脏病有关。 心脏病心脏的神经支配调节心率，从而影响心肌细胞增殖。 此外，神经元释放的神经肽是促进细胞增殖的关键因素。最近的证据 提示来自交感神经和副交感神经系统的神经支配（外在神经支配） 促进出生后小鼠的心肌细胞增殖。Ciona robusta是一种与 脊索动物，它已经记录了保守的特征，如心脏内的神经元（内在神经元）。 与哺乳动物的心脏在出生后不久就停止增殖不同，玻璃海鞘的心脏在发育过程中增殖 直到成年与玻璃海鞘心脏相关的神经元是肽能的，这表明神经肽是 从这些神经元中分泌出来。速激肽是一个保守的神经肽家族，包括P物质， 其与心脏病有关，并且由支配脊椎动物心脏的神经分泌。的 玻璃海鞘神经支配的功能尚不清楚，但我们有初步数据表明， 神经肽速激肽促进发育和成年玻璃海鞘心脏的心脏增殖。唯一的文章 记录玻璃海鞘心脏神经支配尚未跟进，因此我们调查是否有 存在于玻璃海鞘心脏中的未被重视的外在神经支配。我们发现了大脑神经元的证据 （外在的）玻璃海鞘支配心脏的内在神经元。我们假设神经元输入促进了 在发育中的玻璃海鞘心脏中增殖。这一假设得到了我们初步数据的支持， 玻璃海鞘心脏由内源性和外源性神经元支配。此外，我们的数据表明速激肽信号 促进发育中和成年动物的心脏增殖。最后，我们初步的单细胞RNA-seq数据 表明心脏的内在神经元可以对速激肽产生反应。我们提出以下目的，以调查 我们的假设 目的一：表征玻璃海鞘心脏的神经支配。我们将确定时间和空间- 玻璃海鞘心脏的神经支配过程。我们将使用单细胞RNA-seq来鉴定所有细胞的标记物， 心脏中的类型，包括表达速激肽受体（神经激肽）和神经元亚型的类型。 目的二：确定是否神经元信号调节心肌细胞增殖。我们将确定 速激肽激活心肌细胞增殖的发育时间点。接下来我们将防止 在内在神经元或心肌细胞中的速激肽信号传导，以确定速激肽作用于什么细胞类型。 将通过测试生长因子是否间接促进心肌细胞增殖来研究速激肽是否间接促进心肌细胞增殖。 内源性神经元释放的钙离子直接促进心肌细胞增殖。我最终的职业目标是学习 神经支配对心脏发育的作用，在一个主要的本科院校。

Project Summary/Abstract Regulation of cardiomyocyte division is required for proper heart development, and is implicated in congenital heart disease. Neural innervation of the heart regulates heart rate, which impacts cardiomyocyte proliferation. Furthermore, neurons release neuropeptides that are key factors in promoting cell proliferation. Recent evidence suggests neural innervation from the sympathetic and parasympathetic nervous system (extrinsic innervation) of the heart promotes cardiomyocyte proliferation in post-natal mice. Ciona robusta are a closely related chordate, which have documented conserved features such as neurons within the heart (intrinsic neurons). Unlike mammalian hearts that cease proliferating shortly after birth, Ciona hearts proliferate during development and into adulthood. The neurons associated with Ciona hearts are peptidergic, suggesting neuropeptides are secreted from these neurons. Tachykinin is a conserved family of neuropeptides that includes Substance P, which is implicated in cardiac disease, and is secreted from nerves that innervate the heart in vertebrates. The function of neural innervation in Ciona is not known, however we have preliminary data indicating the neuropeptide tachykinin promotes cardiac proliferation in the developing and adult Ciona heart. The sole article documenting Ciona heart innervation has not been followed up, and thus we investigated if there was unappreciated extrinsic innervation that exists in Ciona hearts. We find evidence of neurons from the brain (extrinsic) of Ciona innervating the intrinsic neurons of the heart. We hypothesize that neuronal input promotes proliferation in developing Ciona hearts. This hypothesis is supported by our preliminary data that the developing Ciona heart is innervated by extrinsic and intrinsic neurons. Furthermore, our data suggest tachykinin signaling promotes cardiac proliferation in developing and adult animals. Last, our preliminary single cell RNA-seq data suggest intrinsic neurons in the heart can respond to tachykinin. We propose the following aims to investigate our hypothesis. Aim I: Characterize neuronal innervation of the Ciona heart. We will determine the temporal and spatial time- course of neural innervation of the Ciona heart. We will use single cell RNA-seq to identify markers of all cell types in the heart including those expressing the tachykinin receptor (neurokinin) and subtypes of neurons. Aim II: Determine whether neuronal signaling regulates cardiac cell proliferation. We will identify the developmental time-point(s) which tachykinin activates cardiomyocyte proliferation. Next we will prevent tachykinin signaling in intrinsic neurons or cardiomyocytes to determine what cell type tachykinin acts on. We will investigate if tachykinin promotes cardiomyocyte proliferation indirectly by testing if the growth factors released by intrinsic neurons promote cardiomyocyte proliferation directly. My ultimate career goal is to study the role of neural innervation on cardiac development at a primarily undergraduate institution.