| Project/Area Number |
22KF0211
|
|---|
| Project/Area Number (Other) |
22F22753 (2022)
|
|---|
| Research Category |
Grant-in-Aid for JSPS Fellows
|
| Allocation Type | Multi-year Fund (2023)
Single-year Grants (2022) |
|---|
| Section | 外国 |
|---|
| Review Section |
Basic Section 46010:Neuroscience-general-related
|
|---|
| Research Institution | Kyoto University |
|---|
Principal Investigator |
林 康紀 京都大学, 医学研究科, 教授 (90466037)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
YUEN JESSICA 京都大学, 医学研究科, 外国人特別研究員
|
|---|
| Project Period (FY) |
2023-03-08 – 2025-03-31
|
| Project Status |
Granted (Fiscal Year 2023)
|
| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 2024: ¥500,000 (Direct Cost: ¥500,000)
Fiscal Year 2023: ¥1,100,000 (Direct Cost: ¥1,100,000)
Fiscal Year 2022: ¥600,000 (Direct Cost: ¥600,000)
|
|---|
| Keywords | 記憶固定化 |
|---|
| Outline of Research at the Start |
I set specific aims of this research project as follows:
SA1. To develop a new optogenetic tool that allows us to specifically erase long-term potentiation (LTP) with a defined spatiotemporal window.
SA2. To identify the time window of offline-LTP required for long-term consolidation of memory.
SA3. To identify the cortical circuit modification induced by offline-LTP.
|
| Outline of Annual Research Achievements |
Synaptic localization of endogenous cofilin fused to green fluorescent protein (GFP) was visualized with single synapse resolution in hippocampal CA1 neurons of transgenic mice. The expression of our cofilin-GFP is strictly under the control of Cre recombinase, thus circumventing the problem of protein overexpression via exogenously applied cofilin and allows for direct visualization of cofilin localization in neurons. Structural long-term potentiation (sLTP) was induced by two-photon uncaging of glutamate to confirm endogenous cofilin only accumulates in stimulated spines. The results were in line with the laboratory’s previous publications that showed exogenously administered cofilin accumulates in enlarged dendritic spines following induction of LTP and is involved in memory formation and consolidation in vivo. Next, we sparsely labeled hippocampal CA1 neurons by injection of an adeno-associated virus vector containing iCre to activate expression of endogenous cofilin and mRuby3 as a volume filler. We then utilized the unique properties of our endogenous cofilin to quantify online LTP. Mice were sacrificed following inhibitory avoidance learning for brain sectioning and target hippocampal dendritic spines were analyzed for the ratio of cofilin-GFP to mRuby3 labeling. Results were compared against control mice that did not receive footshocks. After normalizing fluorescence across the groups, we identified spines that have enlarged following learning and thus serve as an indicator of online LTP.
|
| Current Status of Research Progress |
Current Status of Research Progress
3: Progress in research has been slightly delayed.
Reason
Jessica is taking too long time expand animal colonies, which could have been facilitated by using in vitro fertilization. Also, she does not have sufficient knowledge on recombinant DNA technique.
|
| Strategy for Future Research Activity |
Presently, we are attempting to establish a link between online LTP and the accumulation of cofilin in dendritic spines in vivo. The goal is to use cofilin as a synaptic tag to chronically track individual spines that have undergone LTP. We will surgically implant microprisms in the CA1 of our transgenic mice for live imaging of hippocampal apical dendrites. Using the quantification measures obtained in our previous experiments, we can identify individual spines that have undergone LTP and track these spines over months. This method not only allows for chronic imaging of spines prior to and after a learning task at various time points, but also captures the ensuing offline LTP after sleep. The research will provide unprecedented spatiotemporal imaging of both online and offline LTP using endogenous cofilin as a synaptic marker, which has yet to be achieved with existing imaging methods.
|
