ABSTRACT
A vast number of different neuronal activity patterns could each induce a different set of activity-regulated genes. Mapping this coupling between activity pattern and gene induction would allow inference of a neuron's activity-pattern history from its gene expression and improve our understanding of activity-pattern-dependent synaptic plasticity. In genome-scale experiments comparing brief and sustained activity patterns, we reveal that activity-duration history can be inferred from gene expression profiles. Brief activity selectively induces a small subset of the activity-regulated gene program that corresponds to the first of three temporal waves of genes induced by sustained activity. Induction of these first-wave genes is mechanistically distinct from that of the later waves because it requires MAPK/ERK signaling but does not require de novo translation. Thus, the same mechanisms that establish the multi-wave temporal structure of gene induction also enable different gene sets to be induced by different activity durations.
Subject(s)
Cerebral Cortex/physiology , Gene Expression Regulation/physiology , MAP Kinase Signaling System/physiology , Neurons/physiology , Animals , Cells, Cultured , Cerebral Cortex/cytology , Female , Male , Mice , Mice, Inbred C57BL , Mice, Inbred ICR , Photic Stimulation/methods , Rats , Rats, Sprague-DawleyABSTRACT
The ability to chronically monitor neuronal activity in the living brain is essential for understanding the organization and function of the nervous system. The genetically encoded green fluorescent protein-based calcium sensor GCaMP provides a powerful tool for detecting calcium transients in neuronal somata, processes, and synapses that are triggered by neuronal activities. Here we report the generation and characterization of transgenic mice that express improved GCaMPs in various neuronal subpopulations under the control of the Thy1 promoter. In vitro and in vivo studies show that calcium transients induced by spontaneous and stimulus-evoked neuronal activities can be readily detected at the level of individual cells and synapses in acute brain slices, as well as chronically in awake, behaving animals. These GCaMP transgenic mice allow investigation of activity patterns in defined neuronal populations in the living brain and will greatly facilitate dissecting complex structural and functional relationships of neural networks.
Subject(s)
Brain/cytology , Calcium/metabolism , Membrane Potentials/physiology , Neurons/physiology , Retina/cytology , Age Factors , Animals , Biophysics , Calmodulin/genetics , Calmodulin/metabolism , Cell Count , Cell Line, Transformed , Dendrites/metabolism , Dose-Response Relationship, Drug , Electric Stimulation , Gene Expression Regulation/drug effects , Gene Expression Regulation/genetics , Green Fluorescent Proteins/genetics , Green Fluorescent Proteins/metabolism , Humans , In Vitro Techniques , Membrane Potentials/drug effects , Membrane Potentials/genetics , Mice , Mice, Inbred C57BL , Mice, Transgenic , Microscopy, Confocal , Mutation/genetics , Myosin-Light-Chain Kinase/genetics , Myosin-Light-Chain Kinase/metabolism , Neurons/classification , Neurons/drug effects , Odorants , Patch-Clamp Techniques , Peptide Fragments/genetics , Peptide Fragments/metabolism , Potassium Chloride/pharmacology , Thy-1 Antigens/genetics , TransfectionABSTRACT
The acute effect of the potent cyclin-dependent kinase (cdk) inhibitor (R)-roscovitine on Ca(2+) channels inspired the development of structural analogues as a potential treatment for motor nerve terminal dysfunction. On the basis of a versatile chlorinated purine scaffold, we have synthesized ca. 20 derivatives and characterized their N-type Ca(2+) channel agonist action. Agents that showed strong agonist effects were also characterized in a kinase panel for their off-target effects. Among several novel compounds with diminished cdk activity, we identified a new lead structure with a 4-fold improved N-type Ca(2+) channel agonist effect and a 22-fold decreased cdk2 activity as compared to (R)-roscovitine. This compound was selective for agonist activity on N- and P/Q-type over L-type calcium channels.
