Transcriptome analysis of N140fs and T141_L142delinsMISLISV mutations in the zebrafish orthologue of the Alzheimer's disease gene PSEN2

Alzheimer’s disease is the most common form of age-related dementia. At least 15 mutations in the human gene PRESENILIN 2 (PSEN2) have been found to cause familial Alzheimer’s disease (fAD). Zebrafish possess an orthologous gene, psen2, and present opportunities for investigation of PRESENILIN function related to Alzheimer’s disease. The most prevalent and best characterized fAD mutation in PSEN2 is N141I. The equivalent codon in zebrafish psen2 is N140. We used genome editing technology in zebrafish to target generation of mutations to the N140 codon. We isolated two mutations: psen2N140fs, causing truncation of the coding sequence, and psen2T141_L142delinsMISLISV, that deletes the two codons immediately downstream of N140 and replaces them with seven codons coding for amino acid residues MISLISV. Thus, like almost every fAD mutation in the PRESENILIN genes, this latter mutation does not truncate the gene’s open reading frame. Five whole-brain libraries from each of the genotypes: wild type (+/+), heterozygous mutant psen2 (N140fs/+) and heterozygous mutant psen2 (T141_L142delinsMISLISV/+). After sequencing, one sample was identified to be incorrectly genotyped and actually had genotype (N140fs/T141_L142delinsMISLISV). Brains were taken from the zebrafish at age 6 months. All the fish were siblings from mating of a N140fs/+ fish with a T141_L142delinsMISLISV/+ fish and were raised together in the same tank. Both females and male brain samples are included in this study.