Endothelial and systemic upregulation of miR-34a-5p fine-tunes senescence in progeria
Endothelial defects significantly contribute to cardiovascular pathology in the premature aging disease Hutchinson-Gilford progeria syndrome (HGPS). Using an endothelium-specific progeria mouse model, we identify a novel, endothelium-specific microRNA (miR) signature linked to the p53-senescence pathway and a senescence-associated secretory phenotype (SASP). Progerin-expressing endothelial cells exert profound cell-non-autonomous effects initiating senescence in non-endothelial cell populations and causing immune cell infiltrates around blood vessels. Comparative miR expression analyses revealed unique upregulation of senescence-associated miR34a-5p in endothelial cells with strong accumulation at atheroprone aortic arch regions but also, in whole cardiac- and lung tissues as well as in the circulation of progeria mice. Mechanistically, miR34a-5p knockdown reduced not only p53 levels but also late-stage senescence regulator p16 with no effect on p21 levels, while p53 knockdown reduced miR34a-5p and partially rescued p21-mediated cell cycle inhibition with a moderate effect on SASP. These data demonstrate that miR34a-5p reinforces two separate senescence regulating branches in progerin-expressing endothelial cells, the p53- and p16-associated pathways, which synergistically maintain a senescence phenotype that contributes to cardiovascular pathology. Thus, the key function of circulatory miR34a-5p in endothelial dysfunction-linked cardiovascular pathology offers novel routes for diagnosis, prognosis and treatment for cardiovascular aging in HGPS and potentially geriatric patients. This research was supported by by the Austrian Science Fund grant [P 32595 /Grant DOI: 10.55776/P32595] to Selma Osmanagic-Myers, and (I 4694-B) to Roland Foisner, the latter under the frame of EJP RD, the European Joint Programme on Rare Diseases. In addition, this project has received funding from the European Union's Horizon 2020 research and innovation programme under the EJP RD COFUND-EJP N 825575. https://www.doi.org/10.55776/P32595 Overall design: To assess molecular pathways and changes in microRNAs underlying endothelial dysfunction in  Hutchinson-Gilford progeria syndrome (HGPS) and possibly aging population, we isolated endothelial cells as well as their conditioned media and collected plasma from endothelial-specific progerin-transgenic (Prog-Tg), control wild-type lamin A transgenic (LA-Tg) mice and corresponding wild-type control animals (see DOI: 10.18632/aging.203820).  We then performed gene expression and microRNA profiling analysis of endothelial cells, conditioned media (supernatants; Sn) and plasma samples from Prog-Tg, LA-Tg and Wt mice. Subsequently we performed  comparative gene expression profiling analysis of RNA-Seq data for Prog-Tg and LA-Tg with Wt, respectively in endothelial cells (ECs), Sns and plasma samples (each 3 replicates).