Project description:The decline of endothelial autophagy is closely related to vascular senescence and disease, although the molecular mechanisms connecting these outcomes in vascular endothelial cells (VECs) remain unclear. Here, we identify a crucial role for CD44, a multifunctional adhesion molecule, in controlling autophagy and aging in VECs. The CD44 intercellular domain (CD44ICD) negatively regulates autophagy by reducing PIK3R4 and PIK3C3 levels and disrupting STAT3-dependent PtdIns3K complexes. CD44 and its homologue clec-31 are increased in aging vascular endothelium and Caenorhabditis elegans, respectively, suggesting that an age-dependent increase in CD44 induces autophagy decline and aging phenotypes. Accordingly, CD44 knockdown ameliorates age-associated phenotypes in VECs. The endothelium-specific CD44ICD knock-in mouse is shorter-lived, with VECs exhibiting obvious premature aging characteristics associated with decreased basal autophagy. Autophagy activation suppresses the premature aging of human and mouse VECs overexpressing CD44ICD, function conserved in the CD44 homologue clec-31 in C. elegans. Our work describes a mechanism coordinated by CD44 function bridging autophagy decline and aging.
Project description:We identify transcription factor BACH1 as a master regulator in vascular cells during aging. BACH1 is upregulated in the aorta of old mice. We find BACH1 is located on open chromatin and BACH1 binds to CDKN1A gene enhancer and activates its transcription in endothelial cells. Finally, BACH1 aggravates endothelial cell senescence under oxidative stress. Thus, these findings demonstrate a crucial regulatory role of BACH1 in vascular aging.
Project description:Hutchinson-Gilford Progeria Syndrome (HGPS) is a rare, genetic premature aging disorder associated with severe atherosclerosis, often resulting in fatal heart attacks and strokes. Progerin, the mutant protein in HGPS, also is expressed in healthy individuals and may play a role in the development of atherosclerosis during physiologic aging. Here, we provide evidence for a primary involvement of vascular endothelium in the pathogenesis of accelerated atherosclerosis in HGPS. Expression of progerin in cultured human endothelial cells induces a dysfunctional phenotype, manifested by activation of multiple pro-inflammatory, pro-atherogenic genes. In particular, our data implicate endothelial-derived interleukin-1 (IL-1) as a key mediator of a pro-inflammatory vascular phenotype. Endothelial activation also is detectable in a mouse model of HGPS, and appears to be conveyed to neighboring vascular cells via autocrine and paracrine signaling. These new mechanistic insights into the vascular pathobiology of HGPS may have therapeutic implications for this disease. Genome-wide transcriptional profiling was carried out to assess functional phenotypic changes in endothelial cells (EC) as a result of progerin expression. Cultured EC were infected with an adenovirus expressing progerin (Ad-Progerin), and as a control, an adenovirus that did not express any construct (Ad-Null). Experiments were preformed with three different EC cultures.
Project description:Previous studies showed that aging in coronary arteries is associated with pro-inflammatory phenotypic changes and decreased NO bioavailability, which, we hypothesized, promotes vascular disease by inducing endothelial apoptosis. To test this hypothesis we characterized pro-apoptotic alterations in the phenotype of coronary arteries of aged (26 month old) and young (3 month old) F344 rats. DNA fragmentation analysis and TUNEL assay showed that in aged vessels there was a ~4 fold increase in the number of apoptotic endothelial cells. Analysis of the expression of apoptosis-related genes (real-time PCR) showed that in aged coronary arteries there was an increased expression of TNFa, TNFb, caspase 9 and an increased presence of cleaved caspase 3 and caspase 9 (Western blotting), whereas expression of TNFR1 and that of TRADD, Bcl-2, Bcl-X(L), Bid, Bax, caspase 8 and caspase 3 were unchanged. Vascular expression and activity of TNFa convertase enzyme were preserved in aging. We propose that aging-induced up-regulation of TNFa and decreased bioavailability of NO promote endothelial apoptosis in coronary arteries that may lead to the development of endothelial dysfunction and ischemic heart disease in the elderly.
Project description:Dysfunction of vascular endothelium is characteristic of many aging-related diseases, including Alzheimers disease (AD) and AD-related dementias (ADRD). While it is widely posited that endothelial cell dysfunction contributes to the pathogenesis and/or progression of AD/ADRD, it is not clear how. A plausible hypothesis is that intercellular trafficking of extracellular vesicles (EVs) from senescent vascular endothelial cells promotes vascular endothelial cell dysfunction. To test this hypothesis, we compared the expression of proteins and miRNAs in EVs isolated from early passage (EP) vs. senescent (SEN) primary human coronary artery endothelial cells (HCAECs) from the same donor. Proteomics and miRNA libraries constructed from these EV isolates were evaluated using FunRich gene ontology analysis to compare functional enrichment between EP and SEN endothelial cell EVs (ECEVs). Replicative senescence was associated with altered EV abundance and contents independent of changes in EV size. Unique sets of miRNAs and proteins were differentially expressed in SEN-ECEVs, including molecules related to cell adhesion, barrier integrity, receptor signaling, endothelial-mesenchymal transition and cell senescence. miR-181a-5p was the most upregulated miRNA in SEN-ECEVs, increasing >5-fold. SEN-ECEV proteomes supported involvement in several pro-inflammatory pathways consistent with senescence and the senescence-associated secretory phenotype (SASP). These data indicate that SEN-ECEVs are enriched in bioactive molecules implicated in senescence-associated vascular dysfunction, blood-brain barrier impairment, and AD/ADRD pathology. These observations suggest involvement of SEN-ECEVs in the pathogenesis of vascular dysfunction associated with AD/ADRD.
Project description:The critical role of the endothelium in governing vascular, tissues homeostasis and pathological processes is increasingly recognized (Deanfield et al., 2007). Cellular senescence of endothelial cells has been proposed to be involved in endothelial dysfunction and atherogenesis (Minamino T et al., 2007), although the mechanisms underlying the aging induced attenuation of endothelium dependent functions are yet to be clarified. Recent evidences implicated overall miRNA levels and miRNA in regulating angiogenesis and endothelial function (Suarez et al., 2007; Kuehbacher et al., 2007; Harris et al., 2008; Fish et al. 2008; Wang et al., 2008). To investigate the role of miRNAs in endothelial cell senescence, we first profiled the miRNA signature during HUVECs aging (Maciag et al.,1981), through DNA microarray containing 200 oligonucleotide probes complementary to mature forms of miRNAs of human, mouse, and rat origin.
Project description:Aging is a major risk factor for impaired cardiovascular health. The aging myocardium is characterized by microcirculatory and diastolic dysfunction and increased susceptibility to arrhythmias. Nerves align with vessels during development. However, the impact of aging on the cardiac neuro-vascular interface is entirely unknown. Here, we report that aging reduces nerve density specifically in the left ventricle and dysregulates vascular-derived neuro-regulatory genes. Aging leads to a down-regulation of miR-145 and de-repression of the neuro-repulsive factor Semaphorin-3A. miR-145 deletion, which increased Sema3a expression, or endothelial Sema3a overexpression reduced axon density, thus mimicking the observed aged heart phenotype. Removal of senescent cells, which accumulated with chronological age in parallel to the decline in nerve density, rescued age-induced denervation, reduced Sema3a expression, preserved heart rate variability and reduced electrical instability. These data suggest that senescence-associated regulation of neuro-regulatory genes is associated with reduced nerve density and, thereby, contributes to age-associated cardiac dysfunction.
Project description:Age-induced decline in osteogenic potential of bone marrow mesenchymal stem cells (BMSCs) potentiates osteoporosis and increases risk for bone fractures. Despite epidemiology studies reporting concurrent development of vascular- and bone diseases in the elderly, the underlying mechanisms for the vascular-bone cross-talk in aging are largely unknown. In this study, we show that accelerated endothelial aging deteriorates bone tissue through paracrine repression of Wnt-driven-axis in BMSCs. Here, we utilize physiologically aged mice in conjunction with our transgenic endothelial progeria mouse model (Hutchinson-Gilford progeria syndrome; HGPS) that displays hallmarks of an aged bone marrow vascular niche. We find bone defects associated with diminished BMSC osteogenic differentiation that implicate the existence of angiocrine factors with long-term inhibitory effects. microRNA-transcriptomics of HGPS-patient plasma combined with aged-vascular niche analyses in progeria mice reveal abundant secretion of Wnt-repressive microRNA-31-5p. Moreover, we show that inhibition of microRNA-31-5p as well as selective Wnt-activator CHIR99021 boost the osteogenic potential of BMSCs through de-repression and activation of the Wnt-signalling, respectively. Our results demonstrate that the vascular niche significantly contributes to osteogenesis defects in aging and pave ground for microRNA-based therapies of bone loss in elderly.
Project description:NADPH has been long well-recognized as a key cofactor for antioxidant defense and reductive biosynthesis. Here we report a metabolism-independent function of NADPH in modulating epigenetic status and transcription. We found that reduction of cellular NADPH levels by silencing malic enzyme (ME) or G6PD impairs global histone acetylation and transcription in both adipocytes and tumor cells. These effects can be reversed by supplementation of exogenous NADPH or inhibition of histone deacetylase 3 (HDAC3). Mechanistically, NADPH or inhibition of histone deacetylase 3 (HDAC3). Mechanistically,NADPH directly interacts with HDAC3 and interrupts the association between HDAC3 and its co-activator Ncor2 (SMRT) or Ncor1, thereby impairs HDAC3 activation. Interestingly, it appears that NADPH and Ins(1,4,5,6)P4 bind to the same domains on HDAC3, and NADPH has relatively higher affinity towards HDAC3. Thus, while Ins(1,4,5,6)P4 acts as an ‘intermolecular glue’, NADPH may function as a HDAC3-Ncor assembly inhibitor. Collectively, our findings uncovered a previous unidentified and metabolism-independent role of NADPH in controlling epigenetic change and gene expression by acting as an endogenous inhibitor of HDAC3.
Project description:Hutchinson-Gilford Progeria Syndrome (HGPS) is a rare, genetic premature aging disorder associated with severe atherosclerosis, often resulting in fatal heart attacks and strokes. Progerin, the mutant protein in HGPS, also is expressed in healthy individuals and may play a role in the development of atherosclerosis during physiologic aging. Here, we provide evidence for a primary involvement of vascular endothelium in the pathogenesis of accelerated atherosclerosis in HGPS. Expression of progerin in cultured human endothelial cells induces a dysfunctional phenotype, manifested by activation of multiple pro-inflammatory, pro-atherogenic genes. In particular, our data implicate endothelial-derived interleukin-1 (IL-1) as a key mediator of a pro-inflammatory vascular phenotype. Endothelial activation also is detectable in a mouse model of HGPS, and appears to be conveyed to neighboring vascular cells via autocrine and paracrine signaling. These new mechanistic insights into the vascular pathobiology of HGPS may have therapeutic implications for this disease.