
Abstract Background Autosomal-dominant Alzheimer's disease (ADAD) is caused by pathogenic mutations in APP , PSEN1 , and PSEN2 , which usually lead to an early age at onset (< 65). Circular RNAs are a family of non-coding RNAs highly expressed in the nervous system and especially in synapses. We aimed to investigate differences in brain gene expression of linear and circular transcripts from the three ADAD genes in controls, sporadic AD, and ADAD. Methods We obtained and sequenced RNA from brain cortex using standard protocols. Linear counts were obtained using the TOPMed pipeline; circular counts, using python package DCC. After stringent quality control (QC), we obtained the counts for PSEN1 , PSEN2 and APP genes. Only circ PSEN1 passed QC. We used DESeq2 to compare the counts across groups, correcting for biological and technical variables. Finally, we performed in-silico functional analyses using the Circular RNA interactome website and DIANA mirPath software. Results Our results show significant differences in gene counts of circ PSEN1 in ADAD individuals, when compared to sporadic AD and controls (ADAD = 21, AD = 253, Controls = 23—ADADvsCO: log 2 FC = 0.794, p = 1.63 × 10 –04 , ADADvsAD: log 2 FC = 0.602, p = 8.22 × 10 –04 ). The high gene counts are contributed by two circ PSEN1 species (hsa_circ_0008521 and hsa_circ_0003848). No significant differences were observed in linear PSEN1 gene expression between cases and controls, indicating that this finding is specific to the circular forms. In addition, the high circ PSEN1 levels do not seem to be specific to PSEN1 mutation carriers; the counts are also elevated in APP and PSEN2 mutation carriers. In-silico functional analyses suggest that circ PSEN1 is involved in several pathways such as axon guidance ( p = 3.39 × 10 –07 ), hippo signaling pathway ( p = 7.38 × 10 –07 ), lysine degradation (p = 2.48 × 10 –05 ) or Wnt signaling pathway ( p = 5.58 × 10 –04 ) among other KEGG pathways. Additionally, circ PSEN1 counts were able to discriminate ADAD from sporadic AD and controls with an AUC above 0.70. Conclusions Our findings show the differential expression of circ PSEN1 is increased in ADAD. Given the biological function previously ascribed to circular RNAs and the results of our in-silico analyses, we hypothesize that this finding might be related to neuroinflammatory events that lead or that are caused by the accumulation of amyloid-beta.
Autosomal-dominant Alzheimer's disease, Pathway analysis, Research, In-silico functional analysis, Brain, RNA, Circular, Amyloid beta pathway, Amyloid beta-Protein Precursor, Differential expression, Neuroinflammation, Circular PSEN1, Alzheimer Disease, Mutation, Presenilin-1, Humans, Neurology. Diseases of the nervous system, RC346-429, Circular RNA
Autosomal-dominant Alzheimer's disease, Pathway analysis, Research, In-silico functional analysis, Brain, RNA, Circular, Amyloid beta pathway, Amyloid beta-Protein Precursor, Differential expression, Neuroinflammation, Circular PSEN1, Alzheimer Disease, Mutation, Presenilin-1, Humans, Neurology. Diseases of the nervous system, RC346-429, Circular RNA
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