A viral strategy for targeting and manipulating interneurons across vertebrate species

Abstract

A fundamental impediment to understanding the brain is the availability of inexpensive and robust methods for targeting and manipulating specific neuronal populations. The need to overcome this barrier is pressing because there are considerable anatomical, physiological, cognitive, and behavioral differences between mice and higher mammalian species in which it is difficult to specifically target and manipulate genetically defined functional cell-types. In particular, it is unclear the degree to which insights from mouse models can shed light on the neural mechanisms that mediate cognitive functions in higher species including humans. Here we describe a novel recombinant adeno-associated virus (rAAV) that restricts gene expression to GABAergic interneurons within the telencephalon. We demonstrate that the viral expression is specific and robust, allowing for morphological visualization, activity monitoring and functional manipulation of interneurons in both mice and non-genetically tractable species, thus opening the possibility to study GABA-ergic function in virtually any vertebrate species.

A MicroRNA-Based Gene-Targeting Tool for Virally Labeling Interneurons in the Rodent Cortex

“…mAGNETs are orthogonal to other gene regulatory strategies and thus can be easily combined with other cell targeting techniques. For example, short Dlx enhancer elements taken from the distal-less homeobox genes have been shown to be effective in targeting interneurons across several brain regions and species (Lee et al, 2014; Vogt et al, 2014; Dimidschstein et al, 2016). Incorporating the 400-bp-long mDlx enhancer in front of the short hSyn promoter in our AAV-GABA-mAGNET vector may further improve interneuron targeting selectivity in the rat brain.…”

“…While transgenic mouse lines have revolutionized our ability to target specific interneuron types (Taniguchi et al, 2011), it remains difficult to cross-breed transgenic driver lines with transgenic disease models. Virally targeting interneurons has been demonstrated using shortened or non-mammalian promoters (Nathanson et al, 2009a; Delzor et al, 2012) or short cell-type-specific enhancer elements (Lee et al, 2014; Vogt et al, 2014; Dimidschstein et al, 2016). miRNA regulation is orthogonal to promoter and enhancer regulatory elements and represents an additional strategy to achieve interneuron targeting from viral vectors.…”

The BRAIN Initiative Cell Census Consortium: Lessons Learned toward Generating a Comprehensive Brain Cell Atlas

“…Computational approaches that combine various epigenomic signatures such as chromatin modifications/structure and DNA methylation variation allow pinpointing of relatively small (~500–1000 bp) cell-type specific enhancers (Dickel et al, 2016; He et al, 2017; Monti et al, 2017). Similar collections of brain cell type-specific enhancers would provide a means to generate new reagents to target transgene expression to brain regions either in transgenic mice as shown by the Nelson group (Shima et al, 2016) and others (Silberberg et al, 2016), or with viral vectors (Dimidschstein et al, 2016), linking back diverse cell types to their locations/anatomical features in the whole brain.…”

Cortical inhibitory interneurons control sensory processing

“…Furthermore, it will be important in the future to corroborate findings or compare differences with other animals, as application of optogenetic tools in other animal models improves [e.g. 73]. …”