Léa Toury

Hutchinson‐Gilford Progeria Syndrome (HGPS) is a rare, fatal genetic disorder characterized by accelerated aging. The accumulation of an abnormal and toxic protein called progerin within HGPS nuclei disrupts cellular processes, including gene expression and DNA repair. Oxidative stress, resulting from an imbalance between reactive oxygen species (ROS) production and antioxidant defense, is one of the hallmarks of HGPS. To identify novel molecular mechanisms underlying HGPS pathogenesis, we performed miRNA expression profiling in HGPS compared to healthy control fibroblasts. We identified 10 differentially expressed (DE) miRNAs between HGPS and control cells. We focused on miR‐140‐5p and miR‐140‐3p, 2 miRNAs upregulated in HGPS fibroblasts. miR‐140‐5p is known to directly target the transcript of NRF2 , a master regulator of the antioxidant response. Using in vitro mimic and antimiR transfections, we demonstrated that miR‐140‐5p overexpression in HGPS fibroblasts results in the downregulation of the NRF2/KEAP1/HO‐1 antioxidant pathway, leading to increased oxidative stress. Furthermore, our results indicate that miR‐140‐5p overexpression induces mitochondrial dysfunction, characterized by a reduced oxidative phosphorylation capacity and affects other hallmarks of aging. By targeting regulation of oxidative stress and mitochondrial function through NRF2, miR‐140‐5p may play a pivotal role in the pathophysiology of HGPS and open new therapeutic avenues.

MicroRNAs (miRNAs) are small single strand non-coding RNAs and powerful gene expression regulators. They mainly bind to the 3′UTR sequence of targeted mRNA, leading to their degradation or translation inhibition. miR-140 gene encodes the pre-miR-140 that generates the two mature miRNAs miR-140-5p and miR-140-3p. miR-140-5p/-3p have been associated with the development and progression of cancers, but also non-neoplastic diseases. In aging-related diseases, miR-140-5p and miR-140-3p expressions are modulated. The seric levels of these two miRNAs are used as circulating biomarkers and may represent predictive tools. They are also considered key actors in the pathophysiology of aging-related diseases. miR-140-5p/-3p repress targets regulating cell proliferation, apoptosis, senescence, and inflammation. This work focuses on the roles of miR-140-3p and miR-140-5p in aging-related diseases, details their regulation (i.e., by long non-coding RNA), and reviews the molecular targets of theses miRNAs involved in aging pathophysiology.

Progeroid syndromes are rare genetic diseases with most of autosomal dominant transmission, the prevalence of which is less than 1/10,000,000. These syndromes caused by mutations in theLMNAgene encoding A-type lamins belong to a group of disorders called laminopathies. Lamins are implicated in the architecture and function of the nucleus and chromatin. Patients affected with progeroid laminopathies display accelerated aging of mesenchymal stem cells (MSCs)–derived tissues associated with nuclear morphological abnormalities. To identify pathways altered in progeroid patients’ MSCs, we used induced pluripotent stem cells (hiPSCs) from patients affected with classical Hutchinson–Gilford progeria syndrome (HGPS, c.1824C>T—p.G608G), HGPS-like syndrome (HGPS-L; c.1868C>G—p.T623S) associated with farnesylated prelamin A accumulation, or atypical progeroid syndromes (APS; homozygous c.1583C> T—p.T528M; heterozygous c.1762T>C—p.C588R; compound heterozygous c.1583C>T and c.1619T>C—p.T528M and p.M540T) without progerin accumulation. By comparative analysis of the transcriptome and methylome of hiPSC-derived MSCs, we found that patient’s MSCs display specific DNA methylation patterns and modulated transcription at early stages of differentiation. We further explored selected biological processes deregulated in the presence ofLMNAvariants and confirmed alterations of age-related pathways during MSC differentiation. In particular, we report the presence of an altered mitochondrial pattern; an increased response to double-strand DNA damage; and telomere erosion in HGPS, HGPS-L, and APS MSCs, suggesting converging pathways, independent of progerin accumulation, but a distinct DNA methylation profile in HGPS and HGPS-L compared with APS cells.