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Combined In Vivo Anatomical and Functional Tracing of Ventral Tegmental Area Glutamate Terminals in the Hippocampus
Published on: September 9, 2020
An AAV capsid proposed as microglia-targeting directs genetic expression in forebrain excitatory neurons
Wenhao Cao1, Zhiqun Tan2, Bereket T Berackey1
1Department of Anatomy and Neurobiology, School of Medicine, University of California, Irvine, Irvine, CA 92697, USA.
Abstract:
A newly developed capsid AAV-MG1.2 was reported to mediate specific microglial transduction. However, we find that AAV-MG1.2 actually enables specific genetic access to excitatory neurons in forebrain regions including hippocampal formation and visual cortex but does not confer expression in microglia or astrocytes in vivo. Furthermore, we find that AAV-MG1.2 specifically labels the deep layer of the CA1 pyramidal layer in a titer-dependent manner. We show that AAV-MG1.2-Cre can be used to genetically target excitatory neurons for cell-type-specific neural circuit mapping studies. We also find that AAV-MG1.2 conserves specificity for excitatory neurons in rat hippocampus. Thus, the AAV-MG1.2 presents a useful viral-genetic tool for targeting excitatory neurons in the forebrain across different species.
Insights
The AAV-MG1.2 capsid, initially thought to target microglia, actually provides specific genetic access to excitatory neurons in the forebrain. This viral tool enables cell-type-specific neural circuit mapping in various species.
Area of Science:
- Neuroscience
- Molecular Biology
- Viral Vector Technology
Background:
- Adeno-associated virus (AAV) capsids are engineered for cell-type-specific gene delivery.
- AAV-MG1.2 was previously reported to transduce microglia.
- Accurate cell-type targeting is crucial for neuroscience research.
Purpose of the Study:
- To investigate the actual in vivo tropism of the AAV-MG1.2 capsid.
- To determine if AAV-MG1.2 can be used for cell-type-specific genetic access in the brain.
- To evaluate AAV-MG1.2 as a tool for neural circuit mapping.
Main Methods:
- In vivo AAV vector administration in rodent models.
- Analysis of gene expression in brain tissue using immunohistochemistry.
- Titer-dependent analysis of viral transduction patterns.
- Cross-species validation of AAV-MG1.2 tropism.
Main Results:
- AAV-MG1.2 mediates specific genetic access to excitatory neurons in forebrain regions, including the hippocampus and visual cortex.
- AAV-MG1.2 does not confer expression in microglia or astrocytes.
- The capsid specifically labels deep layer CA1 pyramidal neurons in a titer-dependent manner.
- AAV-MG1.2 demonstrates conserved specificity for excitatory neurons in rat hippocampus.
Conclusions:
- AAV-MG1.2 is a valuable tool for targeting excitatory neurons in the forebrain, contrary to previous reports.
- AAV-MG1.2-Cre enables cell-type-specific neural circuit mapping studies.
- The findings highlight the importance of rigorous validation of viral vector tropism across species.
