A bdominal aortic aneurysms (AAAs), characterized by a permanent, localized dilatation (ballooning) of the abdominal aorta that exceeds the normal diameter by >50%, are the most common form of aortic aneurysm. AAA rupture and the associated catastrophic physiological insult carry an overall mortality rate in excess of 80%; ruptured AAAs are the 13th leading cause of death in the United States.1,2 Pathologically, AAAs are characterized by increased inflammatory cell infiltration, aberrant oxidant stress, medial elastin degradation, and medial collagen deposition. Apart from surgery, few medical treatments have been shown to prevent AAA development and growth, 3,4 primarily as a result of the limited understanding of its pathogenic mechanisms.AAAs are found in up to 8% of men aged >65 years. AAA incidence increases steeply by 40% every 5 years in men who Molecular Medicine© 2016 American Heart Association, Inc. Rationale: Uncontrolled growth of abdominal aortic aneurysms (AAAs) is a life-threatening vascular disease without an effective pharmaceutical treatment. AAA incidence dramatically increases with advancing age in men. However, the molecular mechanisms by which aging predisposes individuals to AAAs remain unknown.Objective: In this study, we investigated the role of SIRT1 (Sirtuin 1), a class III histone deacetylase, in AAA formation and the underlying mechanisms linking vascular senescence and inflammation. Methods and Results:The expression and activity of SIRT1 were significantly decreased in human AAA samples.SIRT1 in vascular smooth muscle cells was remarkably downregulated in the suprarenal aortas of aged mice, in which AAAs induced by angiotensin II infusion were significantly elevated. Moreover, vascular smooth muscle cell-specific knockout of SIRT1 accelerated angiotensin II-induced formation and rupture of AAAs and AAArelated pathological changes, whereas vascular smooth muscle cell-specific overexpression of SIRT1 suppressed angiotensin II-induced AAA formation and progression in Apoe −/− mice. Furthermore, the inhibitory effect of SIRT1 on AAA formation was also proved in a calcium chloride (CaCl 2 )-induced AAA model. Mechanistically, the reduction of SIRT1 was shown to increase vascular cell senescence and upregulate p21 expression, as well as enhance vascular inflammation. Notably, inhibition of p21-dependent vascular cell senescence by SIRT1 blocked angiotensin II-induced nuclear factor-κB binding on the promoter of monocyte chemoattractant protein-1 and inhibited its expression. Chen et al Conclusions: SIRT1 Reduction Promotes AAAs 1077are >65 years old, indicating that age is a major risk factor for AAAs.2 Although age-related alterations such as enhanced inflammatory responses, vascular stiffening, and oxidative stress make aged arteries more susceptible to vascular diseases, such as atherosclerosis, 5-7 the reasons why AAAs are often observed in patients with advanced age (>65 years) and how advanced age dramatically accelerates the development and progression of aneurysms in abdominal ...

J.Y. performed mass spectrometry and provided intellectual support for redox subject. J.Y. and K.-S.C. provided technical support for redox modification examination. J.-F.P. performed real-time luciferase assays with the help from D.J. and N.L.. E.-E.Z. conceived LumiCycle design and provided intellectual support for the project. J.-F.P. prepared the illustrations and wrote the manuscript under the guidance of H.-Z.C. and D.-P.L.. J.-H.Q. and J.-M.C. contributed to revision of characters. All authors contributed to data analysis and reviewed the manuscript. H.-Z.C. and D.-P.L. supervised the study.

Cellular senescence (CS), a state of permanent growth arrest, is intertwined with tumorigenesis. Due to the absence of specific markers, characterizing senescence levels and senescence-related phenotypes across cancer types remain unexplored. Here, we defined computational metrics of senescence levels as CS scores to delineate CS landscape across 33 cancer types and 29 normal tissues and explored CS-associated phenotypes by integrating multiplatform data from ~20 000 patients and ~212 000 single-cell profiles. CS scores showed cancer type-specific associations with genomic and immune characteristics and significantly predicted immunotherapy responses and patient prognosis in multiple cancers. Single-cell CS quantification revealed intra-tumor heterogeneity and activated immune microenvironment in senescent prostate cancer. Using machine learning algorithms, we identified three CS genes as potential prognostic predictors in prostate cancer and verified them by immunohistochemical assays in 72 patients. Our study provides a comprehensive framework for evaluating senescence levels and clinical relevance, gaining insights into CS roles in cancer- and senescence-related biomarker discovery.

Summary Both caloric restriction (CR) and mitochondrial proteostasis are linked to longevity, but how CR maintains mitochondrial proteostasis in mammals remains elusive. MicroRNAs (miRNAs) are well known for gene silencing in cytoplasm and have recently been identified in mitochondria, but knowledge regarding their influence on mitochondrial function is limited. Here, we report that CR increases miRNAs, which are required for the CR-induced activation of mitochondrial translation, in mouse liver. The ablation of miR-122, the most abundant miRNA induced by CR, or the retardation of miRNA biogenesis via Drosha knockdown significantly reduces the CR-induced activation of mitochondrial translation. Importantly, CR-induced miRNAs cause the overproduction of mtDNA-encoded proteins, which induces the mitochondrial unfolded protein response (UPR mt ), and consequently improves mitochondrial proteostasis and function. These findings establish a physiological role of miRNA-enhanced mitochondrial function during CR and reveal miRNAs as critical mediators of CR in inducing UPR mt to improve mitochondrial proteostasis.