The long-term goal of this lab is to identify sources of plasticity at the level of single proteins. Our working definition of plasticity at this level is the ability of a protein's behavior to vary, not simply due to an increase or decrease in its activity as with acute activation of an enzyme, but rather by qualitative changes in its behavior. Single N-type Ca channels display heterogeneous activity, called modes, where unitary conductance and kinetics are stable for seconds to minutes before abruptly changing to a new pattern of activity. Because the transitions among modes result in qualitative changes in N-type Ca channel activity, they can be considered plastic proteins. The N-type calcium (Ca) channel is found only in nerve cells and neuronally-derived tissues. It is the most extensively modulated Ca channel in the brain in that more pathways exist for its modulation than for any other, and because of this, it is thought to play a critical role in synaptic plasticity. The proposed experiments test the hypothesis that transmitters exert their actions on N-type Ca channels by activating signaling molecules that shift channel activity from one mode to another.
The specific aims of this project are the following: 1) confirm that phosphorylation of the N-type Ca channel by protein kinase C (PKC) stabilizes an inactivating mode with long openings; 2) determine whether G-proteins protect channels from inactivation; 3) determine whether arachidonic acid (AA)-induced inhibition stabilizes a null activity mode; 4) demonstrate that transmitters, use PKC and AA to modulate N-type currents. Whole cell and unitary N-type currents will be studied with standard patch clamp techniques in superior cervical ganglion neurons, a preparation rich in N-type Ca channels. The effects of signaling molecules on current amplitude, gating kinetics, and rates of transition between different modes will be analyzed quantitatively. We expect to find that transmitters do converge on these signaling molecules to modulate Ca currents by stabilizing particular modes. If true, plasticity of N-type Ca channels may be a building block for emergent forms of plasticity, observed at synapses and in neural circuits. Moreover, these results should establish new signal transduction cascades for N-type Ca channel modulation, which may also be present in central neurons. Further understanding of the modulation of N-type Ca channel modes might allow the design of new pharmaceutical agents that act to stabilize modes which alter net Ca influx. This could help minimize cytotoxicity that can occur during cerebral vasospasm, stroke, epilepsy; and reduce mobility from cognitive, and/or learning and memory disorders.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
5R01NS034195-10
Application #
6921882
Study Section
Special Emphasis Panel (ZRG1-MDCN-4 (01))
Program Officer
Silberberg, Shai D
Project Start
1995-06-01
Project End
2006-07-31
Budget Start
2005-08-01
Budget End
2006-07-31
Support Year
10
Fiscal Year
2005
Total Cost
$278,250
Indirect Cost
Name
University of Massachusetts Medical School Worcester
Department
Physiology
Type
Schools of Medicine
DUNS #
603847393
City
Worcester
State
MA
Country
United States
Zip Code
01655
Roberts-Crowley, Mandy L; Rittenhouse, Ann R (2018) Modulation of CaV1.3b L-type calcium channels by M1 muscarinic receptors varies with CaV? subunit expression. BMC Res Notes 11:681
Roberts-Crowley, Mandy L; Rittenhouse, Ann R (2015) Characterization of ST14A Cells for Studying Modulation of Voltage-Gated Calcium Channels. PLoS One 10:e0132469
Mitra-Ganguli, Tora; Vitko, Iuliia; Perez-Reyes, Edward et al. (2009) Orientation of palmitoylated CaVbeta2a relative to CaV2.2 is critical for slow pathway modulation of N-type Ca2+ current by tachykinin receptor activation. J Gen Physiol 134:385-96
Roberts-Crowley, Mandy L; Mitra-Ganguli, Tora; Liu, Liwang et al. (2009) Regulation of voltage-gated Ca2+ channels by lipids. Cell Calcium 45:589-601
Heneghan, John F; Mitra-Ganguli, Tora; Stanish, Lee F et al. (2009) The Ca2+ channel beta subunit determines whether stimulation of Gq-coupled receptors enhances or inhibits N current. J Gen Physiol 134:369-84
Roberts-Crowley, Mandy L; Rittenhouse, Ann R (2009) Arachidonic acid inhibition of L-type calcium (CaV1.3b) channels varies with accessory CaVbeta subunits. J Gen Physiol 133:387-403
Liu, Liwang; Heneghan, John F; Michael, Gregory J et al. (2008) L- and N-current but not M-current inhibition by M1 muscarinic receptors requires DAG lipase activity. J Cell Physiol 216:91-100
Zhao, Rubing; Liu, Liwang; Rittenhouse, Ann R (2007) Ca2+ influx through both L- and N-type Ca2+ channels increases c-fos expression by electrical stimulation of sympathetic neurons. Eur J Neurosci 25:1127-35