Biology subjects

Aida, T.

Publications and source records attributed to Aida, T..

4 recordsLinked to original sources

bioRxiv2024

Conditional knockout of Shank3 in the ventral CA1 by quantitative in vivo genome-editing impairs social memory

Individuals with autism spectrum disorder (ASD) have a higher prevalence of social memory impairment. A series of our previous studies revealed that hippocampal ventral CA1 (vCA1) neurons possess social memory engram and that the neurophysiological representation of social memory in the vCA1 neurons is disrupted in ASD-associated Shank3 knockout mice. However, whether the dysfunction of Shank3 in vCA1 causes the social memory impairment observed in ASD remains unclear. In this study, we found that vCA1-specific Shank3 conditional knockout (cKO) by the adeno-associated virus (AAV)- or specialized extracellular vesicle (EV)-mediated in vivo gene editing was sufficient to recapitulate the social memory impairment in male mice. Furthermore, the utilization of EV-mediated Shank3-cKO allowed us to quantitatively examine the role of Shank3 in social memory. Our results suggested that there is a certain threshold for the proportion of Shank3-cKO neurons required for social memory disruption. Thus, our study provides insight into the population coding of social memory in vCA1, as well as the pathological mechanisms underlying social memory impairment in ASD.

neuroscience↗

bioRxiv2022

Dynamic and selective engrams emerge with memory consolidation

Episodic memories are encoded by sparse populations of neurons activated during an experience.1 These neural ensembles constitute memory engrams that are both necessary and sufficient for inducing recall even long after memory acquisition.2 This suggests that following encoding, engrams are stabilized to reliably support memory retrieval. However, little is known about the temporal evolution of engrams over the course of memory consolidation or how it impacts mnemonic properties. Here we employed computational and experimental approaches to examine how the composition and selectivity of engrams change with memory consolidation. We modeled engram cells using a spiking recurrent neural network that yielded three testable predictions: memories transition from unselective to selective as neurons are removed from and added to the engram, inhibitory activity during recall is essential for memory selectivity, and inhibitory synaptic plasticity during memory consolidation is critical for engrams to become selective. Using the Cal-Light system to tag activated neurons in vivo with high spatiotemporal precision3 as well as optogenetic and chemogenetic techniques, we conducted contextual fear conditioning experiments that supported each of our models predictions. Our results reveal that engrams are dynamic even within hours of memory consolidation and that changes in engram composition mediated by inhibitory synaptic plasticity are crucial for the emergence of memory selectivity. These findings challenge classical theories of stable memory traces and point to a close link between engram state and memory expression.

neuroscience↗

bioRxiv2020

Prime editing primarily induces undesired outcomes in mice

Genome editing has transformed biomedical science, but is still unpredictable and often induces undesired outcomes. Prime editing (PE) is a promising new approach due to its proposed flexibility and ability to avoid unwanted indels. Here, we show highly efficient PE-mediated genome editing in mammalian zygotes. Utilizing chemically modified guideRNAs, PE efficiently introduced 10 targeted modifications including substitutions, deletions, and insertions across 6 genes in mouse embryos. However, we unexpectedly observed a high frequency of undesired outcomes such as large deletions and found that these occurred more often than pure intended edits across all of the edits/genes. We show that undesired outcomes result from the double-nicking PE3 strategy, but that omission of the second nick largely ablates PE function. However, sequential double-nicking with PE3b, which is only applicable to a fraction of edits, eliminated undesired outcomes. Overall, our findings demonstrate the promising potential of PE for predictable, flexible, and highly efficient in vivo genome editing, but highlight the need for improved variations of PE before it is ready for widespread use.

molecular biology↗

bioRxiv2018

RAD51 Enhances Zygotic Interhomolog Repair

Recent advances in genome editing have greatly improved knock-in (KI) efficiency1-9. Searching for factors to further improve KI efficiency for therapeutic use and generation of non-human primate (NHP) models, we found that the strand exchange protein RAD51 can significantly increase homozygous KI using CRISPR/Cas9 in mouse embryos through an interhomolog repair (IHR) mechanism. IHR is well-described in the context of meiosis10, but only occurs at low frequencies in mitotic cells11,12 and its existence in zygotes is controversial. Using a variety of approaches, we provide evidence for an endogenous IHR mechanism in zygotes that can be enhanced by RAD51. We show that this process can be harnessed for generating homozygous KI animals from wildtype zygotes based on exogenous donors and for converting heterozygous alleles into homozygous alleles without exogenous templates. Furthermore, we elucidate additional factors that contribute to zygotic IHR and identify a RAD51 mutant capable of insertion-deletion (indel)-free stimulation of IHR. Thus, our study provides conclusive evidence for the existence of zygotic IHR and demonstrates methods to enhance IHR for potential use in gene drives, gene therapy, and biotechnology.

molecular biology↗