Project description:Sirtuins are deacetylases or ADP-ribosyltransferases which are implicated in multiple pathways involved in metabolism and life-span regulation. Here, we link the mitochondrial sirtuin SIRT4, which overexpression negatively impacts on mitochondrial oxidative capacity, with premature senescence and skin aging. Accordingly, SIRT4 mRNA levels were significantly increased in vitro in human dermal fibroblasts after repetitive UVB exposure or in senescence triggered by mitotic spindle stress or ionizing radiation. Similarly, analysis of SIRT4 expression in vivo in human skin revealed upregulation of SIRT4 mRNA levels in the dermal compartment of photaged skin as compared with the dermis of intrinsically aged skin. In all our in vitro models, upregulation of SIRT4 expression was associated with decreased levels of miR-15b. Also, in human skin, highest copy numbers of miR-15b mRNA were detected in the epidermis, and epidermal expression was significantly reduced in photoaged skin as compared with intrinsically aged skin. Reduced miR-15b expression is most likely causally linked to increased SIRT4 expression because we found that (i) miR-15b displays a conserved and direct binding site within the 3'-untranslated region of the SIRT4 gene as demonstrated by luciferase reporter assays and (ii) transfection of oligonucleotides mimicking miR-15b function was sufficient to prevent SIRT4 upregulation in senescent cells in vitro. Thus, we propose that miR-15b acts as a negative regulator of SIRT4 expression to antagonize mitochondrial dysfunction and hence cellular senescence as well as tissue aging, in particular photoaging of the skin.
Project description:Skin aging caused by UV is called photoaging, which is characterized by deeper wrinkles accompanied by senescence of dermal fibroblasts and reduction of collagens. Rice fermentation, widely used in the cosmetics, has been reported to possess anti-aging benefits on skincare, however, its roles in the skin photoaging remains unclear. In this study, the effects of Maifuyin (a rice fermentation), and its ingredients succinic acid (SA) and choline on UVA-induced senescence in fibroblasts were evaluated. A mRNA sequencing technology (RNA-seq) was applied to study the effects of these ingredients on UVA-induced photoaging. In conclusion, these results highlight the potential use of Maifuyin and SA as promising agents for anti-photoaging applications.
Project description:Sirtuins are a family of protein deacetylases, deacylases, and ADP-ribosyltransferases that regulate life span, control the onset of numerous age-associated diseases, and mediate metabolic homeostasis. We have uncovered a novel role for the mitochondrial sirtuin SIRT4 in the regulation of hepatic lipid metabolism during changes in nutrient availability. We show that SIRT4 levels decrease in the liver during fasting and that SIRT4 null mice display increased expression of hepatic peroxisome proliferator activated receptor (PPAR ) target genes associated with fatty acid catabolism. Accordingly, primary hepatocytes from SIRT4 knockout (KO) mice exhibit higher rates of fatty acid oxidation than wild-type hepatocytes, and SIRT4 overexpression decreases fatty acid oxidation rates. The enhanced fatty acid oxidation observed in SIRT4 KO hepatocytes requires functional SIRT1, demonstrating a clear cross talk between mitochondrial and nuclear sirtuins. Thus, SIRT4 is a new component of mitochondrial signaling in the liver and functions as an important regulator of lipid metabolism. SIRT4 knockout (KO) and wild-type (WT) littermates (male; n 6 per genotype; 7- to 8-month-old littermates) were sacrificed after a 16-h overnight fast. Samples were individually hybridized on Affymetrix Mouse Genome 430 2.0 GeneChips by the Biopolymers Facility (Harvard Medical School).
Project description:The UVB component of the sunlight (290-320 nm) plays an important role in carcinogenesis through generation of high levels of bipyrimidine DNA photoproducts, while UVA (320-400 nm) has been associated with photoaging and tumor progression through generation of low, but continuous levels of DNA damage and oxidative stress. However, the contribution of UVA light to epidermal cell fate in the context of photoaging remains poorly understood. Here, by using proteomic analyses and biochemical assays for validation, we show that UVA induces proteome remodeling and senescence in primary keratinocytes, eliciting potent antioxidant and pro-inflammatory responses. As a model of early skin tumorigenesis during aging, immortalized non-malignant keratinocytes, bearing potentially oncogenic mutations and dysfunctional components of the senescent machinery , are resilient to UVA-induced stress, but are sensitive to paracrine oxidative stress and immune system activation induced by senescent neighboring keratinocytes. These observations reveal a new cellular mechanism by which UVA induces photoaging in the epidermis.
Project description:Stem cell therapy requires massive scale homogeneous stem cells under strictly qualification control. However, Prolonged ex vivo expansion impairs the biological functions and results in senescence of mesenchymal stem cells (MSCs). We investigated the function of CTDSPL in premature senescence process of MSCs and clarified that miR-18a-5p played a prominent role in preventing senescence of long-term cultured MSCs and promoting the self-renew ability of MSCs. Inhibition of miR-18a-5p promoted the expression of CTDSPL and induced premature senescence of MSCs. Continuous overexpression of miR-18a-5p improved self-renewal of MSCs by reduced ROS level, increased expression of Oct4 and Nanog, promoted growth rate and differentiation capability. We reported for the first time the dynamic interaction of miR-18a-5p and CTDSPL is crucial for stem cell senescence.
Project description:This study describes differential miRNA expression in small intestinal lamina propria leukocyte samples longitudinally during the course of SIV infection of rhesus macaques. Notably, the T-cell activation associated miR-15b, miR-142-3p, miR-142-5p and miR-150 expression was significantly downregulated at 90 and 180DPI. Further, reporter and overexpression assays validated IRAK1 as a direct miR-150 target. Furthermore, IRAK1 protein levels were markedly elevated in intestinal LPLs and epithelium. Finally, blockade of CD8+ T-cell activation/proliferation with delta-9 tetrahydrocannabinol (9-THC) significantly prevented miR-150 downregulation and IRAK1 upregulation. Our findings suggest that miR-150 downregulation during T-cell activation may disrupt the translational control of IRAK1 facilitating persistent GI inflammation.
Project description:Sirtuins are a family of protein deacetylases, deacylases, and ADP-ribosyltransferases that regulate life span, control the onset of numerous age-associated diseases, and mediate metabolic homeostasis. We have uncovered a novel role for the mitochondrial sirtuin SIRT4 in the regulation of hepatic lipid metabolism during changes in nutrient availability. We show that SIRT4 levels decrease in the liver during fasting and that SIRT4 null mice display increased expression of hepatic peroxisome proliferator activated receptor (PPAR ) target genes associated with fatty acid catabolism. Accordingly, primary hepatocytes from SIRT4 knockout (KO) mice exhibit higher rates of fatty acid oxidation than wild-type hepatocytes, and SIRT4 overexpression decreases fatty acid oxidation rates. The enhanced fatty acid oxidation observed in SIRT4 KO hepatocytes requires functional SIRT1, demonstrating a clear cross talk between mitochondrial and nuclear sirtuins. Thus, SIRT4 is a new component of mitochondrial signaling in the liver and functions as an important regulator of lipid metabolism.
Project description:70 miRNAs and 2667 mRNAs were differentially expressed between lung tissue from subjects with COPD and smokers without COPD. miRNA and mRNA expression profiles enriched for biological pathways that may be relevant to the pathogenesis of COPD including the transforming growth factor b, Wnt and focal adhesion pathways. miR-223 and miR-1274a were the most affected miRNAs in subjects with COPD compared with smokers without obstruction. miR-15b was increased in COPD samples compared with smokers without obstruction and localised to both areas of emphysema and fibrosis. miR-15b was differentially expressed within GOLD classes of COPD. Expression of SMAD7, which was validated as a target for miR-15b, was decreased in bronchial epithelial cells in COPD.
Project description:Background: N6-Methyladenosine (m6A) methylation, a common form of RNA modification, play an important role in the pathogenesis of various diseases and in the ontogeny of organisms. Nevertheless, the precise function of m6A methylation in photoaging remains unknown. Objectives: This study aims to investigate the biological role and underlying mechanism of m6A methylation in photoaging. Methods: m6A dot blot, Real-time quantitative PCR (RT-qPCR), western blot and immunohistochemical (IHC) assays were employed to detect the m6A level and specific m6A methylase in ultraviolet ray (UVR)-induced photoaging tissue. The profile of m6A-tagged mRNA was identified by methylated RNA immunoprecipitation sequencing (MeRIP-seq) and RNA-seq analysis. Finally, we investigated the regulatory mechanism of KIAA1429 by MeRIP-qPCR, RNA knockdown and immunofluorescence assay. Results: m6A levels were increased in photoaging and were closely associated with the upregulation of KIAA1429 expression. 1331 differentially m6A methylated genes were identified in the UVR group compared with the control group, of which 1192 (90%) were hypermethylated. Gene ontology analysis showed that genes with m6A hypermethylation and mRNA downregulation were mainly involved in extracellular matrix metabolism and collagen metabolism-related processes. Furthermore, KIAA1429 knockdown abolished the downregulation of TGF-R and upregulation of MMP1 in UVR-irradiated HDFs. Mechanically, we identified MFAP4 as a target of KIAA1429-mediated m6A modification and KIAA1429 might suppress collagen synthesis through an m6A-MFAP4-mediated process. Conclusions: The increased expression of KIAA1429 hinders collagen synthesis during UVR-induced photoaging, suggesting that KIAA1429 represents a potential candidate for targeted therapy to mitigate UVR-driven photoaging.
Project description:The mechanism by which aging induces aortic aneurysm and dissection (AAD) remains unclear. A total of 430 subjects were recruited for screening of differentially expressed plasma microRNAs. We found that miR-1204 was significantly increased in both plasma and aorta of elder patients with AAD, and was positively correlated with age. Cell senescence induced the expression of miR-1204 through p53 interaction with plasmacytoma variant translocation 1, and miR-1204 induced vascular smooth muscle cell (VSMC) senescence to form a positive feedback loop. miR-1204 aggravated angiotensin II-induced AAD formation, and inhibition of miR-1204 attenuated β-aminopropionitrile monofumarate-induced AAD formation. Mechanistically, miR-1204 directly targeted myosin light chain kinase (MYLK) to promote VSMCs to acquire senescence-associated secretory phenotype (SASP) and lose their contractile phenotype. Overexpression of MYLK reversed miR-1204-induced VSMC senescence, SASP and contractile phenotype changes, and the decrease of transforming growth factor-β signaling pathway. Our findings suggest aging aggravates AAD via miR-1204-MYLK signaling axis.