Characterization of circRNA-Associated-ceRNA Networks in a Senescence-Accelerated Mouse Prone 8 Brain

Abstract

Alzheimer's disease (AD) is one of the most common neurodegenerative diseases. Although many researchers have attempted to explain the origins of AD, developing an effective strategy in AD clinical therapy is difficult. Recent studies have revealed a potential link between AD and circRNA-associated-ceRNA networks. However, few genome-wide studies have identified the potential circRNA-associated-ceRNA pairs involved in AD. In this study, we systematically explored the circRNA-associated-ceRNA mechanism in a 7-month-old senescence-accelerated mouse prone 8 (SAMP8) model brain through deep RNA sequencing. We obtained 235 significantly dysregulated circRNA transcripts, 30 significantly dysregulated miRNAs, and 1,202 significantly dysregulated mRNAs. We then constructed the most comprehensive circRNA-associated-ceRNA networks in SAMP8 brain. GO analysis revealed that these networks were involved in regulating the development of AD from various angles, for instance, axon terminus (GO: 0043679) and synapse (GO: 0045202). Following rigorous selection, we discovered that the circRNA-associated-ceRNA networks in this AD mouse model were mainly involved in the regulation of Aβ clearance (Hmgb2) and myelin function (Dio2). This research is the first to provide a systematic dissection of circRNA-associated-ceRNA profiling in SAMP8 mouse brain. The selected circRNA-associated-ceRNA networks can profoundly affect the diagnosis and therapy of AD in the future.

Keywords: Alzheimer’s disease; SAMP8; circRNA-associated-ceRNA.

Figure 1

Memory and Learning Ability Evaluation in the SAMP8 Mouse Model We used the MWM test to evaluate the learning and memory ability in SAMP8 and SAMR1 of 7-month-old mice. (A) Mean escape latency in the hidden platform test. (B) Swimming paths in the probe trial test. (C) Number of crossings in the probe trial test. (D) Time spent in the target quadrant in the probe trial test. (E) Average swimming speeds of mice in the visible-platform test. The data were presented as the mean ± SEM; *p < 0.05.

Figure 2

Cluster Analysis Using a Heatmap (A) Cluster analysis of differentially expressed circRNAs. (B) Cluster analysis of differentially expressed miRNAs. (C) Cluster analysis of differentially expressed mRNAs. Red indicates increased expression, and blue indicates decreased expression.

Figure 3

Validation of Transcript Expression by qPCR between SAMP8 and SAMR1 Mice Mouse β-actin and U6 genes were used as housekeeping internal control. Transcript expression was quantified relative to the expression level of β-actin using the comparative cycle threshold (ΔCT) method. The data were presented as the mean ± SEM (n = 3); *p < 0.05.

Figure 4

circRNA-Associated-ceRNA Networks in SAMP8 Mice The ceRNA networks were based on circRNA-miRNA and miRNA-mRNA interactions. (A) circRNA (up in SAMP8 mice)-miRNA (down in SAMP8 mice)-mRNA (up in SAMP8 mice). (B) circRNA (down in SAMP8 mice)-miRNA (up in SAMP8 mice)-mRNA (down in SAMP8 mice).