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Structured light temporal focusing depth-resolved wide-field FLIM-FRET for in vivo synaptic imaging

用于体内突触成像的结构光时间聚焦深度分辨宽视场 FLIM-FRET

基本信息

批准号：
10467534
负责人：
Elly Nedivi
金额：
$ 28.53万
依托单位：
MASSACHUSETTS INSTITUTE OF TECHNOLOGY
依托单位国家：
美国
项目类别：
财政年份：
2022
资助国家：
美国
起止时间：
2022-02-10 至 2024-01-31
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10467534
关键词：
3-Dimensional Alzheimer&apos s Disease Binding Brain Cell Culture Techniques Cells Chimeric Proteins Cognition Disorders Color Coupled Dendrites Detection Development Dissociation Electron Microscopy Exhibits Fluorescence Fluorescence Microscopy Fluorescence Resonance Energy Transfer Functional disorder Goals Hour Image Individual Label Life Light Measurement Measures Mental disorders Methods Microscope Microscopy Modification Molecular Monitor Morphologic artifacts Motion Mus Neurobiology Neurodegenerative Disorders Neurons Optics Pattern Performance Photons Physiological Presynaptic Terminals Proteins Pyramidal Cells Resolution Scanning Schizophrenia Series Side Signal Transduction Site Specimen Structure Symptoms Synapses Synaptic Cleft System Technology Transfer Testing Thick Time Tissues Variant base chemical bond design detector fluorophore imaging approach improved in vivo in vivo evaluation in vivo monitoring intermolecular interaction millisecond nanometer nanosecond novel strategies parallelization postsynaptic relating to nervous system residence synaptogenesis two-photon

项目摘要

In spite of recent progress, our understanding of cognitive disorders remains tenuous. While outward symptoms of neurodegenerative and mental disorders, ranging from Alzheimer’s to schizophrenia, are readily apparent, their underlying cellular mechanisms are unclear. Most, if not all, exhibit some form of synaptic dysfunction and/or circuit abnormality. Unfortunately, our ability to monitor disruptions in synapse or circuit connectivity as they occur in vivo has been hindered by the difficulty of visualizing individual synaptic contacts at sufficient resolution to discern their formation or elimination. The primary challenge for imaging synaptic connections lies in the narrow cleft separation of 20-50 nm that is far below optical resolution. Here we propose a new approach to identify synapse formation and dissociation in vivo by monitoring the distance between pre- and post-synaptic protein pairs using fluorescence resonance energy transfer (FRET). In Specific aim 1 we will develop wide-field depth-resolved FLIM-FRET by implementing De-scattering with Excitation Patterning (DEEP), a wide-field depth resolved imaging approach based on structured light temporal focusing two-photon excitation that we recently demonstrated is compatible with in vivo neural imaging. We propose implementing DEEP for FLIM by using avalanche photodiode arrays with nanosecond gating to simultaneously resolve lifetimes with over two thousand detectors. For testing microscope development, we will express in the mouse brain, in vivo, known intramolecular FRET pairs using our previously developed methods for sparse, multi-fluorophore neuronal labeling. In Specific aim 2 we will generate a series of FRET donor/acceptor molecules fused to variants of the neuroligin-neurexin trans-synaptic partners in a variety of configurations, designed so that donor-acceptor distance is kept within ~5 nm in the bound state for FRET to occur. These fusion constructs will be screened in cultured neurons and selected based on faithful synaptic localization, lack of interference to normal synaptic dynamics, and the presence of strong FRET signal upon fusion partner binding. The in vivo labeling strategy will be a modification of one we recently developed for imaging Layer 2/3 pyramidal cell dendritic arbors and their resident synapses in vivo using a three-color two-photon system, modified to avoid co-expression of donor and acceptor in the same cell. The postsynaptic fusion protein will be co-expressed with a cell fill to visualize a single targeted cell with all its postsynaptic sites. Where these sites contact labeled presynaptic terminals, transsynaptic binding should place the fluorescent donor/acceptor pairs in close proximity, allowing FRET. Selected pairs will then be tested in vivo in the brain for performance in the presence of autofluorescence and signal loss from scattering in deep layers.

尽管最近取得了进展，但我们对认知障碍的理解仍然薄弱。而向外