Development of a fluorescence indicator for visualizing phosphorylation of transcription factor CREB in vivo

概要

Monitoring single-cell dynamics of intracellular biochemical reactions in vivo remains challenging due to lack of sensitive indicators. Here, I designed and engineered XCREB-G, a green genetically encoded indicator faithfully reporting phosphorylation state of cyclic AMP–responsive element binding protein (CREB), a key transcription factor for long-term plasticity. Using in vivo two-photon microscopy, XCREB-G resolved single-cell CREB dynamics in hundreds of visual cortical neurons. The kinetics of CREB phosphorylation and dephosphorylation induced by visual stimulus was on the timescale of second and a few tens of minute, respectively, overall consistent with previous in vitro studies. Simultaneous dual-color imaging with a red Ca2+ indicator showed “orientation-selective CREB activation” followed relatively large bursts of orientation-selective neuronal activation within 10 s. The CREB activation was induced either by a single round, or a repetitive sequence of sensory-evoked burst. These in vivo results demonstrate sensory information transiently represented with electrical activity is indeed extracted, integrated, and sustained over a longer period as nuclear CREB phosphorylation state.