Characterization of molecular functions, pathways and protein classes affected by aging-related changes of miRNA expression in peripheral blood mononuclear cells. Homo sapiens

Epigenetic drift, an aging-associated change of the epigenome is one of the factors that can influence the rate and course of aging. In fact, even subtle changes of the miRnome can affect cellular functions. Therefore, changes of aging-associated miRNA expression in peripheral blood mononuclear cells (PBMC) of long-lived humans (n=24, mean age 94.8±3.9 years) and healthy, young individuals (n=24, 28.0±4.0 years) was evaluated using next generation sequencing. Twenty three miRNAs had at least 2-fold lower and 9 at least 2-fold higher mean expression in PBMC of long-lived than young study subjects. Expression of select miRNAs was verified by RT-PCR. Target genes were searched for by the MirWalk2 and MirTarBase programs. Next, using bioinformatics tools we analyzed what molecular functions, pathways and protein classes were affected by these miRNAs. Molecular functions, pathways and protein classes were analyzed using the PANTHER Classification System v. 11 database. In total, 12663 target genes have been identified. The largest number of aging-affected miRNAs interacted with mRNA of genes with established role in aging, senescence and/or chronic inflammation such as DISC1 (binding sites for 11 miRNAs), IGF-1R (10), BCL2 (9), MYC (8), TP53 (7), CCND1 (7), CDKN1A (6), CDKN1B (6), FOXO1 (6), XIAP (6), as well as those with a less known or unknown role in these processes such as ZNF460 (13), INPP5B (8), TMEM136 (8), NOTCH2 (8), ZNF652 (8), ACER2 (8), and MAP3K1 (8). Nine molecular functions, 13 pathways and 5 protein classes were indicated as affected by aging-associated miRnome change. Affected molecular functions included signal transducer activity, antigen binding, receptor activity, catalytic activity, binding, nucleic acid binding, G-protein coupled receptor activity, DNA binding, and protein binding. Affected pathways were gonadotropin-releasing hormone receptor pathway, CCKR signaling map, angiogenesis, apoptosis signaling pathway, PDGF signaling pathway, EGF receptor signaling pathway, TGF-β signaling pathway, 5HT2 type receptor mediated signaling pathway, VEGF signaling pathway, integrin signaling pathway, heterotrimeric G-protein signaling pathway-Giα and Gsα mediated pathway, interleukin signaling pathway, and p53 pathway. Protein classes most significantly associated with aging-related change in the miRNA expression were immunoglobulin, nucleic acid binding, defense/immunity protein, transcription factor, and zinc finger transcription factor classes. In conclusion, aging-related miRnome change affects multiple molecular mechanisms in peripheral blood mononuclear cells, intensifying in this way aging-associated dysfunction of the immune system. Overall design: Examination of miRNA expression in mononuclear immune system cells from young and long lived donors