Fluorescent Arc/Arg3.1 indicator mice: A versatile tool to study brain activity changes in vitro and in vivo

Abstract

The brain-specific immediate early gene Arc/Arg3.1 is induced in response to a variety of stimuli, including sensory and behavior-linked neural activity. Here we report the generation of transgenic mice, termed TgArc/Arg3.1-d4EGFP, expressing a 4-hour half-life form of enhanced green fluorescent protein (d4EGFP) under the control of the Arc/Arg3.1 promoter. We show that d4EGFP-mediated fluorescence faithfully reports Arc/Arg3.1 induction in response to physiological, pathological and pharmacological stimuli, and that this fluorescence permits electrical recording from activated neurons in the live mouse. Moreover, the fluorescent Arc/Arg3.1 indicator revealed activity changes in circumscribed brain areas in distinct modes of stress and in a mouse model of Alzheimer’s disease. These findings identify the TgArc/Arg3.1-d4EGFP mouse as a versatile tool to monitor Arc/Arg3.1 induction in neural circuits, both in vitro and in vivo.

Bioluminescence imaging of Arc expression enables detection of activity-dependent and plastic changes in the visual cortex of adult mice

“…In contrast to the superficially obtained fluorescence signals using Venus and d4EGFP (Eguchi and Yamaguchi 2009;Grinevich et al 2009) with some autofluorescence, our results suggested that we were able to detect Fig. 6 Detection of plastic changes in bioluminescence in visual cortex after monocular deprivation in adult Arc-Luc Tg mice.…”

“…The immunohistochemical and Western blot analyses using the anti-Arc and anti-luciferase antibodies supported spatiotemporal expression patterns of the bioluminescence signals accurately reflecting the endogenous Arc and transgenic Luc protein expression patterns. Recently, three research groups have reported the successful in vivo imaging of Arc expression by the knockin of d2EGFP into the Arc locus (Wang et al 2006), the conventional transgenic method using the 7.1-kbp 5 0 upstream region of Arc and the fluorescent protein reporter Venus (Eguchi and Yamaguchi 2009), and the BAC transgenic method using the short-life form d4EGFP (Grinevich et al 2009). The reported expression patterns of Arc-dVenus in the visual cortex of the transgenic mice were similar, as reported here and also in other reports (Kawashima et al 2009;Tagawa et al 2005).…”

“…Using our Arc-Luc Tg mouse strain, we were unable to analyze the Arc-Luc expression at a single-cell level in vivo as previously reported (Wang et al 2006;Grinevich et al 2009). On the other hand, a bioluminescence image could be overlaid on a photograph of a mouse for anatomical reference, as we showed here; however, these 2D images lack 3D information.…”

“…They are the d2-type of enhanced green fluorescent protein (EGFP) gene (d2EGFP) knocked into the Arc locus in mice (Wang et al 2006), the fluorescent protein reporter gene Venus linked to the 7.1 kbp promoter region of Arc in conventional transgenic (Tg) mice (Eguchi and Yamaguchi 2009), and the short-life form of EGFP, d4EGFP, introduced into the bacterial artificial chromosome (BAC) containing Arc in BAC Tg mice (Grinevich et al 2009). Wang et al (2006) successfully monitored Arc expression at a single neuron level from cortical layers II to IV during visual cortical activation using visual stimuli.…”

“…Wang et al (2006) successfully monitored Arc expression at a single neuron level from cortical layers II to IV during visual cortical activation using visual stimuli. The latter two research groups obtained superficial brain fluorescence signals of Venus and d4EGFP from the visual cortex and somatosensory cortex (Eguchi and Yamaguchi 2009;Grinevich et al 2009) with some autofluorescence noise. These groups could not detect signals of Arc expression from deep brain regions such as the hippocampus, and changes in signals associated with experience-dependent plasticity.…”