Rapid, biochemical tagging of cellular activity history in vivo
Nature Methods – August 05, 2024
Source: OpenAlex
Summary
A novel *in vivo* method now noninvasively tags active cells in freely behaving animals, a major advance in *biology*. This *chemistry*-based approach, CaST, rapidly labels cells with elevated calcium within just 10 minutes using an external *biotin* molecule. Crucially, it integrates *cell biology* activity over time, providing immediate readouts, unlike transcriptional reporters requiring hours. This enabled tagging psilocybin-activated neurons and correlating their signal with behavioral responses in untethered mice, offering unprecedented insights into brain function.
Abstract
Abstract Intracellular calcium (Ca 2+ ) is ubiquitous to cell signaling across biology. While existing fluorescent sensors and reporters can detect activated cells with elevated Ca 2+ levels, these approaches require implants to deliver light to deep tissue, precluding their noninvasive use in freely behaving animals. Here we engineered an enzyme-catalyzed approach that rapidly and biochemically tags cells with elevated Ca 2+ in vivo. Ca 2+ -activated split-TurboID (CaST) labels activated cells within 10 min with an exogenously delivered biotin molecule. The enzymatic signal increases with Ca 2+ concentration and biotin labeling time, demonstrating that CaST is a time-gated integrator of total Ca 2+ activity. Furthermore, the CaST readout can be performed immediately after activity labeling, in contrast to transcriptional reporters that require hours to produce signal. These capabilities allowed us to apply CaST to tag prefrontal cortex neurons activated by psilocybin, and to correlate the CaST signal with psilocybin-induced head-twitch responses in untethered mice.