Author
Guido M. Gaietta
Bio: Guido M. Gaietta is an academic researcher from University of California, San Diego. The author has contributed to research in topics: Endoplasmic reticulum & Golgi apparatus. The author has an hindex of 18, co-authored 27 publications receiving 3782 citations.
Papers
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TL;DR: This approach was used to show that newly synthesized connexin43 was transported predominantly in 100- to 150-nanometer vesicles to the plasma membrane and incorporated at the periphery of existing gap junctions, whereas older connexins were removed from the center of the plaques into pleiomorphic vesicle of widely varying sizes.
Abstract: Recombinant proteins containing tetracysteine tags can be successively labeled in living cells with different colors of biarsenical fluorophores so that older and younger protein molecules can be sharply distinguished by both fluorescence and electron microscopy. Here we used this approach to show that newly synthesized connexin43 was transported predominantly in 100- to 150-nanometer vesicles to the plasma membrane and incorporated at the periphery of existing gap junctions, whereas older connexins were removed from the center of the plaques into pleiomorphic vesicles of widely varying sizes. Selective imaging by correlated optical and electron microscopy of protein molecules of known ages will clarify fundamental processes of protein trafficking in situ.
920 citations
TL;DR: Examination of transected dendrites revealed that both AMPAR subunits were synthesized in dendrite and that activity blockade enhanced dendritic synthesis of GluR1 but not GluGluR2, and point out the advantages of using FlAsH-EDT2 and ReAs H- EDT2 for studying the trafficking of newly synthesized proteins in local cellular compartments such as dendreys.
Abstract: Regulation of AMPA receptor (AMPAR) trafficking is important for neural plasticity. Here we examined the trafficking and synthesis of the GluR1 and GluR2 subunits using ReAsH-EDT2 and FlAsH-EDT2 staining. Activity blockade of rat cultured neurons increased dendritic GluR1, but not GluR2, levels. Examination of transected dendrites revealed that both AMPAR subunits were synthesized in dendrites and that activity blockade enhanced dendritic synthesis of GluR1 but not GluR2. In contrast, acute pharmacological manipulations increased dendritic synthesis of both subunits. AMPARs synthesized in dendrites were inserted into synaptic plasma membranes and, after activity blockade, the electrophysiological properties of native synaptic AMPARs changed in the manner predicted by the imaging experiments. In addition to providing a novel mechanism for synaptic modifications, these results point out the advantages of using FlAsH-EDT2 and ReAsH-EDT2 for studying the trafficking of newly synthesized proteins in local cellular compartments such as dendrites.
528 citations
TL;DR: FRET from CFP to FlAsH reports GPCR activation in living cells without disturbing receptor function and shows that the small size of the tetracysteine-biarsenical tag can be decisively advantageous.
Abstract: Fluorescence resonance energy transfer (FRET) from cyan to yellow fluorescent proteins (CFP/YFP) is a well-established method to monitor protein-protein interactions or conformational changes of individual proteins. But protein functions can be perturbed by fusion of large tags such as CFP and YFP. Here we use G protein-coupled receptor (GPCR) activation in living cells as a model system to compare YFP with the small, membrane-permeant fluorescein derivative with two arsen-(III) substituents (fluorescein arsenical hairpin binder; FlAsH) targeted to a short tetracysteine sequence. Insertion of CFP and YFP into human adenosine A(2A) receptors allowed us to use FRET to monitor receptor activation but eliminated coupling to adenylyl cyclase. The CFP/FlAsH-tetracysteine system gave fivefold greater agonist-induced FRET signals, similar kinetics (time constant of 66-88 ms) and perfectly normal downstream signaling. Similar results were obtained for the mouse alpha(2A)-adrenergic receptor. Thus, FRET from CFP to FlAsH reports GPCR activation in living cells without disturbing receptor function and shows that the small size of the tetracysteine-biarsenical tag can be decisively advantageous.
490 citations
TL;DR: Two major RNA-binding proteins, nucleolin and YB-1, are identified that specifically bind to the JNK response element in the 5' untranslated region (UTR) of interleukin-2 mRNA.
Abstract: Regulated mRNA turnover is a highly important process, but its mechanism is poorly understood. Using interleukin-2 (IL-2) mRNA as a model, we described a role for the JNK-signaling pathway in stabilization of IL-2 mRNA during T-cell activation, acting via a JNK response element (JRE) in the 5' untranslated region (UTR). We have now identified two major RNA-binding proteins, nucleolin and YB-1, that specifically bind to the JRE. Binding of both proteins is required for IL-2 mRNA stabilization induced by T-cell activation signals and for JNK-induced stabilization in a cell-free system that duplicates essential features of regulated mRNA decay. Nucleolin and YB-1 are required for formation of an IL-2 mRNP complex that responds to specific mRNA stabilizing signals.
389 citations
TL;DR: It is shown for the first time that Pannexin1 is glycosylated at Asn-254 and that this residue is important for plasma membrane targeting, and proposed that N-glycosylation of Pan Nexin1 could be a significant mechanism for regulating the trafficking of these membrane proteins to the cell surface in different tissues.
276 citations
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TL;DR: This work introduced a method for optically imaging intracellular proteins at nanometer spatial resolution and used this method to image specific target proteins in thin sections of lysosomes and mitochondria and in fixed whole cells to image retroviral protein Gag at the plasma membrane.
Abstract: We introduce a method for optically imaging intracellular proteins at nanometer spatial resolution. Numerous sparse subsets of photoactivatable fluorescent protein molecules were activated, localized (to approximately 2 to 25 nanometers), and then bleached. The aggregate position information from all subsets was then assembled into a superresolution image. We used this method--termed photoactivated localization microscopy--to image specific target proteins in thin sections of lysosomes and mitochondria; in fixed whole cells, we imaged vinculin at focal adhesions, actin within a lamellipodium, and the distribution of the retroviral protein Gag at the plasma membrane.
7,924 citations
TL;DR: Recent studies have begun to shed light on the physiological functions of MAPK cascades in the control of gene expression, cell proliferation and programmed cell death.
Abstract: Mitogen-activated protein kinases (MAPKs) are important signal transducing enzymes, unique to eukaryotes, that are involved in many facets of cellular regulation. Initial research concentrated on defining the components and organization of MAPK signalling cascades, but recent studies have begun to shed light on the physiological functions of these cascades in the control of gene expression, cell proliferation and programmed cell death.
4,973 citations
TL;DR: This review will focus on the JNK group of MAP kinases, which are characterized by the sequence TEY and the two stress-activatedMAP kinases: p38 with the sequence TGY, and the c-Jun NH2-terminal kinases (JNK) with the sequences TPY.
4,228 citations
TL;DR: This work reviews those forms of LTP and LTD for which mechanisms have been most firmly established and examples are provided that show how these mechanisms can contribute to experience-dependent modifications of brain function.
3,767 citations
TL;DR: This review discusses International Union of Basic and Clinical Pharmacology glutamate receptor nomenclature, structure, assembly, accessory subunits, interacting proteins, gene expression and translation, post-translational modifications, agonist and antagonist pharmacology, allosteric modulation, mechanisms of gating and permeation, roles in normal physiological function, as well as the potential therapeutic use of pharmacological agents acting at glutamate receptors.
Abstract: The mammalian ionotropic glutamate receptor family encodes 18 gene products that coassemble to form ligand-gated ion channels containing an agonist recognition site, a transmembrane ion permeation pathway, and gating elements that couple agonist-induced conformational changes to the opening or closing of the permeation pore. Glutamate receptors mediate fast excitatory synaptic transmission in the central nervous system and are localized on neuronal and non-neuronal cells. These receptors regulate a broad spectrum of processes in the brain, spinal cord, retina, and peripheral nervous system. Glutamate receptors are postulated to play important roles in numerous neurological diseases and have attracted intense scrutiny. The description of glutamate receptor structure, including its transmembrane elements, reveals a complex assembly of multiple semiautonomous extracellular domains linked to a pore-forming element with striking resemblance to an inverted potassium channel. In this review we discuss International Union of Basic and Clinical Pharmacology glutamate receptor nomenclature, structure, assembly, accessory subunits, interacting proteins, gene expression and translation, post-translational modifications, agonist and antagonist pharmacology, allosteric modulation, mechanisms of gating and permeation, roles in normal physiological function, as well as the potential therapeutic use of pharmacological agents acting at glutamate receptors.
3,044 citations