Department of Organismal Biology, Uppsala University, Uppsala 752 36, Sweden.
Oramacell, Paris 75006, France.
eNeuro. 2019 Oct 31;6(5). doi: 10.1523/ENEURO.0198-19.2019. Print 2019 Sep/Oct.
Transgenic mouse lines are instrumental in our attempt to understand brain function. Promoters driving transgenic expression of the gene encoding are crucial to ensure selectivity in Cre-mediated targeting of floxed alleles using the Cre-Lox system. For the study of dopamine (DA) neurons, promoter sequences driving expression of the () gene are often implemented and several DAT-Cre transgenic mouse lines have been found to faithfully direct Cre activity to DA neurons. While evaluating an established DAT-Cre mouse line, reporter gene expression was unexpectedly identified in cell somas within the amygdala. To indiscriminately explore Cre activity in DAT-Cre transgenic lines, systematic whole-brain analysis of two DAT-Cre mouse lines was performed upon recombination with different types of floxed reporter alleles. Results were compared with data available from the Allen Institute for Brain Science. The results identified restricted DAT-Cre-driven reporter gene expression in cell clusters within several limbic areas, including amygdaloid and mammillary subnuclei, septum and habenula, areas classically associated with glutamatergic and GABAergic neurotransmission. While no gene expression was detected, ample co-localization between DAT-Cre-driven reporter and markers for glutamatergic and GABAergic neurons was found. Upon viral injection of a fluorescent reporter into the amygdala and habenula, distinct projections from non-dopaminergic DAT-Cre neurons could be distinguished. The study demonstrates that DAT-Cre transgenic mice, beyond their usefulness in recombination of floxed alleles in DA neurons, could be implemented as tools to achieve selective targeting in restricted excitatory and inhibitory neuronal populations within the limbic neurocircuitry.
转基因小鼠品系在我们试图理解大脑功能方面发挥了重要作用。启动子驱动基因编码的转基因表达对于确保使用 Cre-Lox 系统对 floxed 等位基因进行 Cre 介导的靶向的选择性至关重要。对于多巴胺 (DA) 神经元的研究，通常实施驱动 () 基因表达的启动子序列，并且已经发现几种 DAT-Cre 转基因小鼠线能够忠实地将 Cre 活性引导至 DA 神经元。在评估已建立的 DAT-Cre 小鼠线时，出乎意料地在杏仁核内的细胞体中鉴定出报告基因表达。为了在 DAT-Cre 转基因品系中不加区别地探索 Cre 活性，对两种 DAT-Cre 小鼠线进行了系统的全脑分析，与不同类型的 floxed 报告基因等位基因进行重组。结果与艾伦脑科学研究所提供的数据进行了比较。结果鉴定了在几个边缘区域内的细胞簇中受限的 DAT-Cre 驱动的报告基因表达，包括杏仁核和乳突亚核、隔核和缰核，这些区域与谷氨酸能和 GABA 能神经传递经典相关。虽然未检测到 基因表达，但在 DAT-Cre 驱动的报告基因和谷氨酸能和 GABA 能神经元标志物之间发现了丰富的共定位。在将荧光报告基因注射到杏仁核和缰核后，可以区分来自非多巴胺能 DAT-Cre 神经元的不同投射。该研究表明，除了在 DA 神经元中重组 floxed 等位基因方面的有用性之外，DAT-Cre 转基因小鼠还可以用作工具，以实现对边缘神经回路中受限的兴奋性和抑制性神经元群体的选择性靶向。
