AUTHOR=Hasuike Yuhei , Mochizuki Hideki , Nakamori Masayuki 

TITLE=Expanded CUG Repeat RNA Induces Premature Senescence in Myotonic Dystrophy Model Cells

JOURNAL=Frontiers in Genetics

VOLUME=13

YEAR=2022

URL=https://www.frontiersin.org/journals/genetics/articles/10.3389/fgene.2022.865811

DOI=10.3389/fgene.2022.865811

ISSN=1664-8021

ABSTRACT=<p>Myotonic dystrophy type 1 (DM1) is a dominantly inherited disorder due to a toxic gain of function of RNA transcripts containing expanded CUG repeats (CUG<sup>exp</sup>). Patients with DM1 present with multisystemic symptoms, such as muscle wasting, cognitive impairment, cataract, frontal baldness, and endocrine defects, which resemble accelerated aging. Although the involvement of cellular senescence, a critical component of aging, was suggested in studies of DM1 patient-derived cells, the detailed mechanism of cellular senescence caused by CUG<sup>exp</sup> RNA remains unelucidated. Here, we developed a DM1 cell model that conditionally expressed CUG<sup>exp</sup> RNA in human primary cells so that we could perform a detailed assessment that eliminated the variability in primary cells from different origins. Our DM1 model cells demonstrated that CUG<sup>exp</sup> RNA expression induced cellular senescence by a telomere-independent mechanism. Furthermore, the toxic RNA expression caused mitochondrial dysfunction, excessive reactive oxygen species production, and DNA damage and response, resulting in the senescence-associated increase of cell cycle inhibitors p21 and p16 and secreted mediators insulin-like growth factor binding protein 3 (IGFBP3) and plasminogen activator inhibitor-1 (PAI-1). This study provides unequivocal evidence of the induction of premature senescence by CUG<sup>exp</sup> RNA in our DM1 model cells.</p>