b2-adrenoceptor signaling is critical for adrenergic regulation of synaptic plasticity and neurodegeneration, and has been proposed to have therapeutic potentials for Alzheimer?s and Parkinson?s diseases. However, b- adrenoceptors (b-ARs) exhibit highly complicated pharmaceutical effects. This is exemplified by clinical results, in which b-AR drugs modulate receptor paralogs in different organs to elicit both therapeutic and clinically harmful effects at the same time.
We aim to understand the signaling specificity of b2-adrenoceptors (b2-ARs), mechanisms through which they are selectively coupled to different intracellular signaling proteins and molecular effectors under different conditions. Our published and preliminary results manifest the signaling scaffold, synapse-associated protein of 97 kDa (SAP97) as an orchestrator of b2-AR signaling in hippocampal neurons. Specifically, the b-isoform of SAP97 (S97b) tethers b2-ARs and the effector voltage-gated potassium channel subunit Kv1.1 together to transduce activation of b2-AR signaling into inhibition of Kv1.1 and its removal from the dendrite surface (collectively referred to as Kv1.1 inhibition). Consequently, b2-AR-induced Kv1.1 inhibition increases dendritic excitability and lowers the induction threshold for long-term synaptic potentiation. Given b2-AR-signaling also regulates the phosphorylation of the AMPA receptor subunit GluA1, but through a different signaling scaffold, we hypothesize that signaling scaffolds mediate the signaling specificity and the interactions can be used as specific pharmacological targets. In this proposal, using the S97b/b2-AR/Kv1.1 complex as an exemplary model, we aim to gain mechanistic insights into a) how the diverse b2-AR signaling events are specifically regulated; b), what the molecular components of the S97b/b2-AR/Kv1.1 complex are to achieve signaling specificity; and c) what are the behavioral correlates of the S97b/b2-AR/Kv1.1 signaling pathway in mice. Importantly, in SAP97-lacking neurons, the signaling pathway governing b2-AR dependent dendritic excitability is impaired with a ~100% penetrance, allowing an analysis with minimal confounding effects of functional redundancy. The outcomes of our proposed experiments will provide a set of mechanistically clear drug targets for treating psychiatric, neurological, immunological or cardiovascular disorders, and perhaps more importantly lead to a novel and generalizable molecular scheme, through which G-protein-coupled receptors achieve biased and selective regulations of specific effector proteins to modulate synaptic transmission and plasticity.

Public Health Relevance

Neuromodulatorschangethestateofneuralcircuitstoalterhowtheyrespondtoextrinsicsignals.Thecurrent applicationaimstounderstandhowsignalingscaffoldsachievesignalingspecificitybylinkingG-proteincoupled receptorswiththesignalingmachineryanddownstreameffectorproteins.UsingSAP97-regulatedb?2- adrenoceptor-mediatedKv1.1inhibitioninCA1pyramidalneuronsasaheuristiccellularmodel,weaimto identifythemolecularunderpinningsofsignaltransduction,mediatingfacilitationoflong-termsynapticplasticity inductionforspecificformsofhippocampus-dependentlearning.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
Research Project (R01)
Project #
1R01NS107604-01A1
Application #
9740257
Study Section
Neurobiology of Learning and Memory Study Section (LAM)
Program Officer
Leenders, Miriam
Project Start
2019-03-01
Project End
2024-02-28
Budget Start
2019-03-01
Budget End
2020-02-29
Support Year
1
Fiscal Year
2019
Total Cost
Indirect Cost
Name
University of Pittsburgh
Department
Neurosciences
Type
Schools of Arts and Sciences
DUNS #
004514360
City
Pittsburgh
State
PA
Country
United States
Zip Code
15260