Laura Valgaeren, Belgium
University of Antwerp Faculty of Pharmaceutical, Biomedical and Veterinary SciencesAuthor Of 1 Presentation
IN-SITU SEQUENCING OF ABCA7 IN HUMAN ALZHEIMER’S DISEASE BRAIN REVEALS SPATIAL EXPRESSION PATTERNS
Abstract
Aims
ABCA7 is one of the most compelling risk genes for Alzheimer’s disease (AD). However, it remains unclear what the exact role is of ABCA7 (isoforms) in AD pathogenesis and which cell-types it is expressed in. Gaining a better understanding of ABCA7 spatial expression could lead to increased insight into the disease.
Methods
We conducted a pilot study on the use of Cartana’s in-situ sequencing (ISS) to study spatial expression using post-mortem brain samples (hippocampus, prefrontal cortex, cerebellum) of four AD patients, with varying ABCA7 mutations, and one healthy control. A custom assay was designed including 7 probes for different ABCA7 isoforms and 15 cell-type specific markers. After ISS, DAPI staining was performed. Cell-type enrichment was studied in 14 unique subregions using both a cell-segmentation method using Fiji in Image J, and spatial clustering using Ripley’s K in the R package spatstat.
Results
Expression of ABCA7 was generally low with lowest expression in the hippocampal fimbriae (less than 0.2% of all transcripts) and highest in the granular layer of the cerebellum (1.8%) and especially the choroid plexus (almost 8%). Both cell segmentation and spatial clustering seemed to give an indication of enrichment of ABCA7 in neurons (1.35 enrichment, p-value 0.03), but not microglia.
Conclusions
Although further optimization of the technique and analysis is needed, our data proves that it could be a useful technique to study AD-related genes and pinpoint neurons and choroid plexus as being of specific interest for further ABCA7 studies.