Dataset Information

Base editing strategy for insertion of the A673T mutation in the APP gene to prevent the development of AD in vitro.

ABSTRACT: The amyloid precursor protein (APP) is a transmembrane protein mostly found in neurons. Cleavage of this protein by β-secretase can lead to the formation of amyloid-β (Aβ) peptide plaque, which leads to Alzheimer's disease. Genomic analysis of an Icelandic population that did not show symptoms of Alzheimer's at an advanced age led to the discovery of the A673T mutation. This mutation can reduce β-secretase cleavage by 40%. We hypothesized that the insertion of this mutation in patients' neurons could be an effective and sustainable method of slowing down or even stopping the progression of Alzheimer's disease. We modified the APP gene in HEK293T cells and in SH-SY5Y neuroblastoma using a Cas9 nickase (Cas9n)-deaminase enzyme to convert the alanine codon to a threonine. Several Cas9n-deaminase variants were tested to compare their efficiency of conversion. The results were characterized and quantified by deep sequencing. We successfully introduced the A673T mutation in 53% of HEK293T cells alongside a new mutation (E674K), which seemed to further reduce Aβ peptide accumulation. Our approach aimed to provide a new strategy for the treatment of Alzheimer's and in so doing, demonstrate the capacity of base editing techniques for treating genetic diseases.

SUBMITTER: Guyon A

PROVIDER: S-EPMC7985668 | biostudies-literature | 2021 Jun

REPOSITORIES: biostudies-literature

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Base editing strategy for insertion of the A673T mutation in the APP gene to prevent the development of AD <i>in vitro</i>.

Guyon Antoine A Rousseau Joël J Bégin Francis-Gabriel FG Bertin Tom T Lamothe Gabriel G Tremblay Jacques P JP

Molecular therapy. Nucleic acids 20210301

The amyloid precursor protein (<i>APP</i>) is a transmembrane protein mostly found in neurons. Cleavage of this protein by β-secretase can lead to the formation of amyloid-β (Aβ) peptide plaque, which leads to Alzheimer's disease. Genomic analysis of an Icelandic population that did not show symptoms of Alzheimer's at an advanced age led to the discovery of the A673T mutation. This mutation can reduce β-secretase cleavage by 40%. We hypothesized that the insertion of this mutation in patients' n ...[more]

PMID: 33815938

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Project description:ImportanceRecently, a rare variant in the amyloid precursor protein gene (APP) was described in a population from Iceland. This variant, in which alanine is replaced by threonine at position 673 (A673T), appears to protect against late-onset Alzheimer disease (AD). We evaluated the frequency of this variant in AD cases and cognitively normal controls to determine whether this variant will significantly contribute to risk assessment in individuals in the United States.ObjectiveTo determine the frequency of the APP A673T variant in a large group of elderly cognitively normal controls and AD cases from the United States and in 2 case-control cohorts from Sweden.Design, setting, and participantsCase-control association analysis of variant APP A673T in US and Swedish white individuals comparing AD cases with cognitively intact elderly controls. Participants were ascertained at multiple university-associated medical centers and clinics across the United States and Sweden by study-specific sampling methods. They were from case-control studies, community-based prospective cohort studies, and studies that ascertained multiplex families from multiple sources.Main outcomes and measuresGenotypes for the APP A673T variant were determined using the Infinium HumanExome V1 Beadchip (Illumina, Inc) and by TaqMan genotyping (Life Technologies).ResultsThe A673T variant genotypes were evaluated in 8943 US AD cases, 10 480 US cognitively normal controls, 862 Swedish AD cases, and 707 Swedish cognitively normal controls. We identified 3 US individuals heterozygous for A673T, including 1 AD case (age at onset, 89 years) and 2 controls (age at last examination, 82 and 77 years). The remaining US samples were homozygous for the alanine (A673) allele. In the Swedish samples, 3 controls were heterozygous for A673T and all AD cases were homozygous for the A673 allele. We also genotyped a US family previously reported to harbor the A673T variant and found a mother-daughter pair, both cognitively normal at ages 72 and 84 years, respectively, who were both heterozygous for A673T; however, all individuals with AD in the family were homozygous for A673.Conclusions and relevanceThe A673T variant is extremely rare in US cohorts and does not play a substantial role in risk for AD in this population. This variant may be primarily restricted to Icelandic and Scandinavian populations.

Dataset Information

Base editing strategy for insertion of the A673T mutation in the APP gene to prevent the development of AD in vitro.

Publications

Base editing strategy for insertion of the A673T mutation in the APP gene to prevent the development of AD <i>in vitro</i>.

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