Stephen R. Ikeda, MD, PhD, Chief

Steven R. Ikeda MD. , PhD. Chief
National Institute on Alcohol Abuse and Alcoholism
National Institutes of Health
5625 Fishers Lane, Room TS-11A:MSC 9411
Bethesda MD 20892-9413
telephone: +1 301.443.2807
fax: +1 301.480.0466
e-mail: sikeda@mail.nih.gov

The goals of the Laboratory are to explore molecular mechanisms contributing to synaptic transmission and neuronal excitability at the molecular, cellular and organismic level. An emphasis is placed on developing new technologies to explore neuronal cellular and subcellular signaling pathways based on advanced optical techniques.

The Section on Transmitter Signaling, headed by Dr. Stephen R. Ikeda, focuses primarily on determining the molecular mechanisms underlying G-protein coupled receptor (GPCR) modulation of neuronal high-threshold Ca2+ channels in neuronal systems using electrophysiological and molecular techniques. A second goal is the development of optical sensors based on fluorescence resonance energy transfer (FRET) and reporter protein complementation to examine GPCR activity in living cells. Techniques in the laboratory include whole-cell voltage-clamp, heterologous expression in neurons by microinjection and viral techniques, wide-field FRET imaging, and total internal reflectance fluorescence microscopy. GPCRs (e.g., CB1, CRF, mGluR, NPY, and nociceptin receptors) comprise major cellular targets for pharmaceuticals used in the treatment of alcoholism and other addictive disorders. Additionally, N-type Ca2+ channels and heterotrimeric G-protein signaling pathways utilizing GJ31 have been directly implicated in ethanol reward and consumption mechanisms. Thus, increasing our knowledge of the basic mechanisms underlying GPCR modulation of Ca2+ and other ion channels should help clarify molecular mechanisms underlying the therapeutic efficacy of agents used for the treatment of alcoholism and addiction.

The Section on Cellular Biophotonics, headed by Dr. Steven S. Vogel, is focused on understanding how cells integrate exocytosis and endocytosis to regulate the abundance and assembly of membrane proteins on the cell surface. Toward this end his section has been developing advanced imaging techniques for the determination of protein-protein interaction and protein complex stoichiometry in living cells. Techniques available in the section include single- and two-photon laser scanning confocal microscopy, FRET imaging, spectral imaging, fluorescence lifetime imaging (FLIM), and time-resolved and steady state anisotropy. Model systems used in the laboratory include: Developing sea urchin eggs, transfected cell lines, and primary hippocampal neurons in culture. One project in the Section is investigating a form of endocytosis that occurs at cleavage furrows and appears to be required for cell division. The second project involves using FRET imaging to study protein-protein interactions in synapses.

The Section on Model Synaptic Systems, headed by Dr. Fumihito Ono, focuses on the cellular and molecular mechanisms underlying synaptic transmission in the vertebrate model organism Danio rerio (zebrafish). Zebrafish are genetically malleable, optically transparent at early stages of development, and amenable to higher throughput methodologies. Extensive regions of synteny between zebrafish and human genomes make Danio an ideal model for translational research.

The transparent nature of the early zebrafish embryo meshes well with the advanced imaging and electrophysiological expertise within the Laboratory.

The integration of the three Sections is designed to bring together investigators with common interests in molecules involved in neuronal excitability and synaptic transmission yet expertise in diverse but complementary techniques. The emphasis on model systems facilitates the application, from the cellular to organismic level, of new technologies in an efficient and cost- effective manner.