Supersensitive Ras activation in dendrites and spines revealed by two-photon fluorescence lifetime imaging

Ryohei Yasuda, Christopher D. Harvey, Haining Zhong, Aleksander Sobczyk, Linda Van Aelst, Karel Svoboda

Research output: Contribution to journalArticle

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Abstract

To understand the biochemical signals regulated by neural activity, it is necessary to measure protein-protein interactions and enzymatic activity in neuronal microcompartments such as axons, dendrites and their spines. We combined two-photon excitation laser scanning with fluorescence lifetime imaging to measure fluorescence resonance energy transfer at high resolutions in brain slices. We also developed sensitive fluorescent protein-based sensors for the activation of the small GTPase protein Ras with slow (FRas) and fast (FRas-F) kinetics. Using FRas-F, we found in CA1 hippocampal neurons that trains of back-propagating action potentials rapidly and reversibly activated Ras in dendrites and spines. The relationship between firing rate and Ras activation was highly nonlinear (Hill coefficient ∼5). This steep dependence was caused by a highly cooperative interaction between calcium ions (Ca2+) and Ras activators. The Ras pathway therefore functions as a supersensitive threshold detector for neural activity and Ca2+ concentration.

Original languageEnglish (US)
Pages (from-to)283-291
Number of pages9
JournalNature Neuroscience
Volume9
Issue number2
DOIs
StatePublished - Feb 1 2006

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ASJC Scopus subject areas

  • Neuroscience(all)

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