@article {49060, title = {A robotic multidimensional directed evolution approach applied to fluorescent voltage reporters.}, journal = {Nature Chemical Biology}, year = {2018}, month = {2018 Feb 26}, abstract = {

We developed a new way to engineer complex proteins toward multidimensional specifications using a simple, yet scalable, directed evolution strategy. By robotically picking mammalian cells that were identified, under a microscope, as expressing proteins that simultaneously exhibit several specific properties, we can screen hundreds of thousands of proteins in a library in just a few hours, evaluating each along multiple performance axes. To demonstrate the power of this approach, we created\ a genetically encoded fluorescent voltage indicator, simultaneously optimizing its\ brightness and membrane localization using our microscopy-guided cell-picking strategy. We produced the high-performance opsin-based fluorescent voltage reporter Archon1 and demonstrated its utility by imaging spiking and millivolt-scale subthreshold and synaptic activity in acute mouse brain slices and in larval zebrafish in vivo. We also measured postsynaptic responses downstream of optogenetically controlled neurons in C. elegans.

}, issn = {1552-4469}, doi = {10.1038/s41589-018-0004-9}, author = {Piatkevich, Kiryl D and Jung, Erica E and Straub, Christoph and Linghu, Changyang and Park, Demian and Suk, Ho-Jun and Hochbaum, Daniel R and Goodwin, Daniel and Pnevmatikakis, Eftychios and Pak, Nikita and Kawashima, Takashi and Yang, Chao-Tsung and Jeff L Rhoades and Shemesh, Or and Asano, Shoh and Yoon, Young-Gyu and Freifeld, Limor and Saulnier, Jessica L and Riegler, Clemens and Engert, Florian and Hughes, Thom and Drobizhev, Mikhail and Szabo, Balint and Ahrens, Misha B and Flavell, Steven W and Sabatini, Bernardo L and Boyden, Edward S} } @article {6514, title = {Caged naloxone reveals opioid signaling deactivation kinetics.}, journal = {Molecular Pharmacology}, volume = {84}, year = {2013}, month = {2013 Nov}, pages = {687-95}, abstract = {

The spatiotemporal dynamics of opioid signaling in the brain remain poorly defined. Photoactivatable opioid ligands provide a means to quantitatively measure these dynamics and their underlying mechanisms in brain tissue. Although activation kinetics can be assessed using caged agonists, deactivation kinetics are obscured by slow clearance of agonist in tissue. To reveal deactivation kinetics of opioid signaling we developed a caged competitive antagonist that can be quickly photoreleased in sufficient concentrations to render agonist dissociation effectively irreversible. Carboxynitroveratryl-naloxone (CNV-NLX), a caged analog of the competitive opioid antagonist NLX, was readily synthesized from commercially available NLX in good yield and found to be devoid of antagonist activity at heterologously expressed opioid receptors. Photolysis in slices of rat locus coeruleus produced a rapid inhibition of the ionic currents evoked by multiple agonists of the μ-opioid receptor (MOR), but not of α-adrenergic receptors, which activate the same pool of ion channels. Using the high-affinity peptide agonist dermorphin, we established conditions under which light-driven deactivation rates are independent of agonist concentration and thus intrinsic to the agonist-receptor complex. Under these conditions, some MOR agonists yielded deactivation rates that are limited by G protein signaling, whereas others appeared limited by agonist dissociation. Therefore, the choice of agonist determines which feature of receptor signaling is unmasked by CNV-NLX photolysis.

}, issn = {1521-0111}, doi = {10.1124/mol.113.088096}, author = {Banghart, Matthew R and Williams, John T and Shah, Ruchir C and Lavis, Luke D and Sabatini, Bernardo L} } @article {65014, title = {Calcium signaling in dendritic spines.}, journal = {Cold Spring Harb Perspect Biol}, volume = {4}, year = {2012}, month = {2012 Apr 01}, pages = {a005686}, abstract = {

Calcium (Ca(2+)) is a ubiquitous signaling molecule that accumulates in the cytoplasm in response to diverse classes of stimuli and, in turn, regulates many aspects of cell function. In neurons, Ca(2+) influx in response to action potentials or synaptic stimulation triggers neurotransmitter release, modulates ion channels, induces synaptic plasticity, and activates transcription. In this article, we discuss the factors that regulate Ca(2+) signaling in mammalian neurons with a particular focus on Ca(2+) signaling within dendritic spines. This includes consideration of the routes of entry and exit of Ca(2+), the cellular mechanisms that establish the temporal and spatial profile of Ca(2+) signaling, and the biophysical criteria that determine which downstream signals are activated when Ca(2+) accumulates in a spine. Furthermore, we also briefly discuss the technical advances that made possible the quantitative study of Ca(2+) signaling in dendritic spines.

}, keywords = {Action Potentials, Animals, Calcium Signaling, Dendritic Spines, Mammals, Neuronal Plasticity}, issn = {1943-0264}, doi = {10.1101/cshperspect.a005686}, author = {Higley, Michael J and Sabatini, Bernardo L} }