Generation and validation of a D1 dopamine receptor Flpo knock-in mouse

Abstract

BackgroundDopamine is a powerful neuromodulator of diverse brain functions, including movement, motivation, reward, and cognition. D1-type dopamine receptors (D1DRs) are the most prevalently expressed dopamine receptors in the brain. Neurons expressing D1DRs are heterogeneous and involve several subpopulations. Studying these neurons has been limited by current animal models, especially when considering their integration with conditional or intersectional genetic tools. New methodTo address this limitation, we developed a novel Drd1-P2A-Flpo (Drd1-Flpo) mouse line in which the Flpo gene was knocked in immediately after the Drd1 gene using CRISPR-Cas9. We validated the Drd1-Flpo line by confirming Flp expression and functionality specific to D1DR+ neurons. Comparison with existing methods: The Drd1-Flpo line is useful resource for studying subpopulation of D1DR+ neurons with intersectional genetic tools. ConclusionsWe demonstrated brain-wide GFP expression driven by Drd1-Flpo, suggesting that this mouse line may be useful for comprehensive anatomical and functional studies in many brain regions. The Drd1-Flpo model will advance the study of dopaminergic signaling by providing a new tool for investigating the diverse roles of D1DR+ neurons and their subpopulations in brain disease. Significance StatementThe roles of dopamine in the brain are mediated by dopamine receptors. D1-type dopamine receptors (D1DRs) and D1DR-expressing (D1DR+) neurons play important roles in various brain functions. We generated a Drd1-Flpo mouse line that expresses Flp recombinase in D1DR+ neurons. This novel Drd1-Flpo mouse facilitates investigation of specific roles of D1DR+ neurons in various brain areas including the striatum, frontal cortex, and cerebellum, and it provides an alternative to existing Drd1-Cre mice. In addition, the Drd1-Flpo mouse line provides a tool for intersectional genetic studies, when used with existing transgenic Cre lines. The Drd1-Flpo mouse line can help unravel the specific contributions of D1DR+ neuron subpopulations to brain function and dysfunction.