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CRCNS: Regulation of assembly and disassembly of the postsynaptic density during synaptic plasticity and its effect on AMPAR trapping

Award Number: R01MH129066
ORGANIZATION: NATIONAL INSTITUTE OF MENTAL HEALTH
OPDIV: NIH
AWARD CLASS: DISCRETIONARY
AWARD ACTIVITY TYPE: SCIENTIFIC/HEALTH RESEARCH (INCLUDES SURVEYS)

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Fast glutamatergic synaptic transmission is based on a precise and complex molecular organization which requires the control of the number of AMPA-type glutamate receptors (AMPARs) at the postsynaptic sites of glutamatergic synapses on dendritic spines. The number of AMPARs varies as a function of pre- and postsynaptic activation history of the synapse. It is now well described that synapses can change their number of AMPARs and therefore, their response properties through biochemical mechanisms of synaptic plasticity. In this way, information is stored in the brain. The overall goal of this project is to use quantitative models and experiments to answer two fundamental questions about the role of an abundant postsynaptic protein, synGAP, in regulation of the numbers of AMPARs. Numerous experiments in intact neurons have revealed that the level of synGAP expressed at synapses is inversely correlated with the amount of AMPARs available at the synapses, and that synGAP helps to regulate changes in AMPAR numbers during synaptic plasticity. The enzymatic GAP domain of synGAP acts as a ratchet to adjust the rates of addition and removal of AMPARs from the surface of the dendrite. SynGAP also contains a sight that binds tightly to the major scaffold protein PSD-95 via its three protein-binding PDZ domains. Important to the mental health mission of the NIMH, SynGAP plays a critical role in learning and memory in the Brain and mutation of SynGAP is implicated in cognitive disabilities. The project is divided into two broad Aims. In Aim 1, we will answer the question: What are the mechanisms by which synGAP controls the amount of AMPA receptor in the postsynaptic density (PSD) - by control of surface amount and/or by control of availability of PDZ domain binding sites in the synapse? We will improve our existing computational model of the competition between synGAP and AMPARs for binding to PSD-95 by incorporating it into our model of AMPAR trafficking. We will use genetics and sophisticated molecular engineering to experimentally disentangle the two mechanisms. Effects on the nano-organization of AMPARs will be measured by super- resolution fluorescence microscopy and electrophysiology. Results of these experiments will be used to constrain our model of AMPAR trafficking. Aim 2, Through the synergy of experimental and computational approaches, we will address the questions: How does the formation of the condensate between synGAP and PSD-95, and the presence of additional PDZ domain-binding proteins (GluN2 receptor subunits, neuroligin, nNOS, CRIPT, etc.) influence the nano-organization of AMPAR-TARPs in the PSD in the basal state and during synaptic plasticity? RELEVANCE (See instructions): We propose a combination of computational and experimental work that will help clarify the role of synGAP in regulation of AMPARs in CNS synapses, including its role in mental illness. The work will impact a specific medical condition termed “SynGAP haploinsufficiency” or “MRD5”, in which SynGAP is mutated in ~1% of children with sporadic non-syndromic cognitive disability accompanied by autism and/or epilepsy. The medical impacts of this work are potentially quite significant as it could help to point toward specific molecular interventions with therapeutics that could improve the lives of patients with these afflictions.


Issue Date FY	Funding FY	Legal Entity Name	Legal Entity Address	Legal Entity City	Legal Entity State	Legal Entity Zip Code	Legal Entity COUNTY	Legal Entity COUNTRY	Assistance Listing	Award Code	Budget Year	Action Date	Action Type	Action Amount

Issue Date FY: 2024 ( Subtotal = $304,492 )
2024	2024	SALK INSTITUTE FOR BIOLOGICAL STUDIES, SAN DIEGO, CALIFORNIA, THE	10010 N TORREY PINES RD	LA JOLLA	CA	92037	SAN DIEGO	USA	Mental Health Research Grants	000	4	4/23/2024	NON-COMPETING CONTINUATION	$304,492
														Subtotal = $304,492

Issue Date FY: 2023 ( Subtotal = $304,492 )
2023	2023	SALK INSTITUTE FOR BIOLOGICAL STUDIES, SAN DIEGO, CALIFORNIA, THE	10010 N TORREY PINES RD	LA JOLLA	CA	92037	SAN DIEGO	USA	Mental Health Research Grants	000	3	4/27/2023	NON-COMPETING CONTINUATION	$304,492
														Subtotal = $304,492

Issue Date FY: 2022 ( Subtotal = $304,492 )
2022	2022	SALK INSTITUTE FOR BIOLOGICAL STUDIES, SAN DIEGO, CALIFORNIA, THE	10010 N TORREY PINES RD	LA JOLLA	CA	92037	SAN DIEGO	USA	Mental Health Research Grants	000	2	4/25/2022	NON-COMPETING CONTINUATION	$304,492
														Subtotal = $304,492

Issue Date FY: 2021 ( Subtotal = $326,992 )
2021	2021	SALK INSTITUTE FOR BIOLOGICAL STUDIES, SAN DIEGO, CALIFORNIA, THE	10010 N TORREY PINES RD	LA JOLLA	CA	92037	SAN DIEGO	USA	Mental Health Research Grants	000	1	7/15/2021	NEW	$326,992
														Subtotal = $326,992

Grand Total All Awards = $1,240,468

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CRCNS: Regulation of assembly and disassembly of the postsynaptic density during synaptic plasticity and its effect on AMPAR trapping

Award Number: R01MH129066

ORGANIZATION: NATIONAL INSTITUTE OF MENTAL HEALTH

OPDIV: NIH

AWARD CLASS: DISCRETIONARY

AWARD ACTIVITY TYPE: SCIENTIFIC/HEALTH RESEARCH (INCLUDES SURVEYS)

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