Lower blood levels of miR‐29b‐3p in healthy middle‐aged AD risk gene carriers

Abstract

AbstractBackgroundA number of late‐onset Alzheimer’s disease (AD) risk genes have been discovered, among which the most studied but not fully explored is the apolipoprotein E gene (APOE). PICALM (coding Phosphatidylinositol Binding Clathrin Assembly Protein) is another well‐recognized risk‐gene, shown to interact with the APOE gene in conferring AD risk. MicroRNAs (miRNAs) are post‐transcriptional regulators of mRNAs, some of which are known to be involved in AD pathology. The purpose of this study was to investigate in middle‐aged, healthy participants the association between AD risk‐genes (APOE and PICALM) and circulating miRNAs that were previously identified as altered in AD patients.MethodBlood samples were collected from 76 healthy individuals (36 F, 36 M; age: 56.38±3.16), assigned to three groups: A+P+ (APOE/PICALM risk), A+P‐ (APOE risk, PICALM neutral alleles) and N group (APOE/PICALM neutral alleles). RT‐qPCR was used to compare the levels of 11 microRNA identified by us in previous studies as candidate early AD biomarkers in blood plasma (hsa‐miR‐29b‐3p, hsa‐miR‐34a‐5p, hsa‐miR‐125b, hsa‐miR‐146a, hsa‐miR‐135a, hsa‐miR‐30b‐5p, hsa‐miR‐142‐3p, hsa‐miR‐200a‐3p, hsa‐miR‐483‐5p, hsa‐miR‐486‐5p, hsa‐miR‐502‐3p) [1, 2]. We followed standard procedures of blood assays.ResultSingle gene risk (APOE) carriers had lower levels of miR‐29b‐3p than non‐carriers and double risk carriers (F(2,73) = 12.75, p < 0.001 with Welch homogeneity correction; post‐hoc with Tukey correction: p < 0.01 for A+P‐ versus N, p < 0.001 for A+P‐ versus A+P+). No other changes in miRNA panels were discovered.ConclusionDownregulation of miR‐29b‐3p in blood was detected repeatedly before in patients with AD, in 4 independent studies [1]. Here we show the same effect in a subpopulation of middle‐age, healthy individuals with APOE related genetic risk for AD. Further research is needed to understand the interaction reversing this effect in PICALM risk carriers. Longitudinal follow‐up may validate this blood‐based miRNA not only as an easy‐to‐access diagnostic biomarker, but also as a risk‐assessment biomarker for AD prevention.Funding: This work was funded by the Polish National Science Centre (NCN) grant no. 2018/31/N/HS6/03551, 2016/20/W/NZ4/00354 and 2018/29/B/NZ7/02757.[1], [2] https://doi.org/10.1016/j.arr.2018.10.008; 10.18632/oncotarget.15109.