Identification of Functional miRNAs Regulating Plasma Membrane Damage-dependent Senescence in Human Fibroblasts

Abstract

Okinawa Institute of Science and Technology Graduate UniversityDoctor of PhilosophyDamage to the plasma membrane is common in nature, caused by a variety of triggers ranging from physical damage to cell-autonomous activities. Our previous study has revealed that cellular senescence, a state of irreversible cell cycle arrest that contributes to organismal aging, is one of the cellular outcomes that can be triggered by plasma membrane damage. Upon the induction of plasma membrane damage-dependent senescence (PMD-Sen), human diploid fibroblasts exhibit senescence features, including increased β-galactosidase activity, the manifestation of senescence-associated secretory phenotypes, and the upregulation of senescence marker proteins, including p53, p21, and p16. However, the molecular mechanisms underlying PMD-Sen remain unclear. Given that substantial alterations in gene expression are associated with the onset of senescence, it is essential to investigate the regulatory mechanisms responsible for gene expression changes during cellular senescence. MicroRNAs (miRNAs), a large class of small noncoding RNAs, have been identified as critical regulators of gene expression by targeting messenger RNAs (mRNAs). When miRNAs bind to the 3’ untranslated region (3’UTR) of target mRNAs, they primarily inhibit translation or promote degradation of the target mRNAs. In this study, to identify regulatory miRNA-mRNA pairs in PMD-Sen cells, I performed an integrated analysis of miRNA and mRNA expression profiles in a time-resolved manner. My analysis suggests that a total of 2495 miRNA-mRNA pairs, comprising 65 miRNAs, are involved in the process of PMD-Sen. The results support the hypothesis that miRNAs regulate senescence induction by post-transcriptionally regulating their target mRNAs. Furthermore, an overlap was identified between the set of miRNA-mRNA pairs implicated in PMD-Sen and DNA damage-induced senescence (DDR-Sen), leading to the identification of 41 shared miRNAs in the pairs. This suggests common regulatory miRNA-mRNA pairs across different senescent cell subtypes. Notably, miR-155-5p emerged as the miRNA with the largest number of shared miRNA-mRNA pairs that exhibit a highly negative correlation. These findings imply that miR-155-5p may have a role in PMD-Sen and DDR-Sen.doctoral thesi