Synaptic Targeting in Hard-Wired Neural Circuits

什么是硬连线精确突触连接的分子指令？只有对生存最关键的行为才是硬连线在基因组中。呼吸和原始反射等其他行为是不被学习的，所以控制它们的神经电路必须使用精确的分子指令预先指定。目前，我们对硬连线神经电路的形成知之甚少。我的长期目标是识别出每一个必要的和足够的分子来连接硬连线的神经电路。我的总体假设是，只有少数(&lt；需要不同的细胞表面分子来产生不同的硬连接突触靶向模式。我的实验方法将使用单个识别的神经元的转录组测序，并结合参与突触靶向的细胞表面受体的系统特征。具体地说，我们将分离具有刻板印象的硬连接突触连接的单个识别神经元，并对它们的RNA基因产物进行测序。通过比较来自同一动物的两对不同连接的神经元之间的基因表达模式，我们将识别预先决定其突触连接的分子。为了了解这些分子是如何被这些神经元使用的，我们将从功能上表征创建神经元精确连接模式所需的所有细胞表面受体。最后，我们将在另一个神经元中表达这些分子，以重新连接其突触连接，改变其功能，从而改变动物的感知和行为。这项研究将是第一次展示确切的遗传指令，这些指令可以完全硬连接和错误连接神经电路。通过了解细胞表面的关键分子如何产生错误的突触连接，我们可以研究纠正它的方法。我们提出的工作是朝着理解内在行为背后的分子指令迈出的重要的第一步。

What are the molecular instructions to hard-wire precise synaptic connections?  Only the most critical behaviours for survival are hard-wired into the genome.   Behaviours such as breathing and primitive reflexes are not learned, and so the neural circuitry that controls them must be pre-specified using precise molecular instructions.  Currently, we know very little about how hard-wired neural circuits are formed.  My long term goal is to identify every molecule necessary and sufficient to wire up a hard-wired neural circuit. My overall hypothesis is that only a small number (< 50) of different cell-surface molecules are required to generate a distinct hard-wired synaptic targeting pattern.   My experimental approach will use transcriptome sequencing of single identified neurons in concert with a systematic characterization of cell-surface receptors involved in synaptic targeting.      Specifically, we will isolate single identified neurons with stereotyped hard-wired synaptic connectivities and sequence their RNA gene products.   By comparing the gene expression patterns between pairs of differentially-connected neurons from the same animal, we will identify the molecules that pre-determine their synaptic connectivities.   To understand how these molecules are used by these neurons, we will functionally characterize all cell-surface receptors required to create the neuron's precise wiring pattern.   Finally, we will express these molecules in another neuron to re-wire its synaptic connections, alter its function, and thus alter the animal's perception and behaviour.   This research will be the first demonstration of the exact genetic instructions that can completely hardwire and mis-wire a neural circuit.   By understanding how key molecules at the cell surface can produce erroneous synaptic connections, we can investigate ways to correct it.  Our proposed work is an important first step towards understanding the molecular instructions underlying innate behaviours.