450 East 29th Street
New York, NY 10016
Our lab is particularly interested in studying multiple modes of synaptic vesicle fusion. The opening of Ca2+ channels drives at least two distinct forms of fusion. In the classical mode, the vesicle membrane fully merges with and flattens into the presynaptic membrane (full collapse fusion). In a newly characterized mode, termed "kiss-and-run," the connection between the vesicle interior and the external medium lasts long enough to allow passage of neurotransmitter, but the connection is severed before the identity of the vesicle is lost. We study the dynamic properties and functional implications of both fusion modes by loading single synaptic vesicles with single photoluminescent reporter particles?quantum dots. Sharp distinctions between full collapse fusion and kiss-and-run are now in hand. Experiments are underway to monitor the same fusion event optically and electrophysiologically.
One area of intense attention in our lab is the fundamental unit of cell-cell communication between brain neurons: quantal synaptic transmission. Presynaptic release of a packet of neurotransmitter, for example, glutamate, causes activation of postsynaptic receptors and a brief flow of current that promotes firing of the postsynaptic cell. We work on neuronal mechanisms that allow synapses to adapt to a sudden or long-lasting change in their level of activity. For example, blockade of impulses or of postsynaptic glutamate receptors causes a cascade of biochemical events that eventually leads to readjustment of critical molecular players on both sides of the synapse. We use state-of-the art methods to pin down the cell biology of changes in synaptic strength, of importance for adaptation of brain networks in learning and memory. Ongoing work in cultures of isolated neurons and brain slices.
We study how synaptic transmission and depolarization cause changes in neuronal gene expression. Despite its importance, signaling from synapse or surface membrane to nucleus is only partly understood. One example of such signaling involves a local increase in Ca2+ concentration near a class of Ca2+ channels (L-type) different from those that trigger presynaptic transmitter release, subsequently leading to activation of an exemplar transcription factor, CREB, a regulator of transcription of many important neuronal genes. Our approach is to combine physiological approaches (how fast, how steeply voltage-dependent, how is signal transduced) and biochemical experiments using cDNA microarrays (which genes, in what context, what relationship to learning and memory).
Evolutionary and functional perspectives on signaling from neuronal surface to nucleus
Cohen, Samuel M; Li, Boxing; Tsien, Richard W; Ma, Huan
2015-06-27; 1090-2104,Biochemical & biophysical research communications - id: 1639732, year: 2015 REVIEW
The impact of NMDA receptor hypofunction on GABAergic neurons in the pathophysiology of schizophrenia
Cohen, Samuel M; Tsien, Richard W; Goff, Donald C; Halassa, Michael M
2015-01-19; 1573-2509,Schizophrenia research - id: 1436132, year: 2015 JOURNAL ARTICLE
Distinct roles of multiple isoforms of CaMKII in signaling to the nucleus
Ma, H; Li, B; Tsien, RW
2015-04-10; 0167-4889,Biochimica & biophysica acta. Molecular cell research - id: 1523982, year: 2015
CaV1.2 Calcium Channels: Just Cut Out to Be Regulated?
Groth, Rachel D; Tirko, Natasha N; Tsien, Richard W
2014-07-07; 0896-6273,Neuron - id: 1061872, year: 2014 Journal Article
Cntnap4 differentially contributes to GABAergic and dopaminergic synaptic transmission
Karayannis, T; Au, E; Patel, J C; Kruglikov, I; Markx, S; Delorme, R; Heron, D; Salomon, D; Glessner, J; Restituito, S; Gordon, A; Rodriguez-Murillo, L; Roy, N C; Gogos, J A; Rudy, B; Rice, M E; Karayiorgou, M; Hakonarson, H; Keren, B; Huguet, G; Bourgeron, T; Hoeffer, C; Tsien, R W; Peles, E; Fishell, G
2014-08-08; 0028-0836,Nature - id: 1102842, year: 2014 Journal Article; Research Support, N.I.H., Extramural; Research Support, Non-U.S. Gov't