Introduction: Abdominal aortic aneurysms (AAA) are characterized by localized inflammation, extracellular matrix degradation, and apoptosis of smooth muscle cells, which together lead to progressive and irreversible aortic dilation. Major risk factors for AAA include smoking and aging, both of which prominently alter gene expression via epigenetic mechanisms, including histone methylation (me) and acetylation (ac).However, little is known about epigenomic dynamics during AAA formation. Here, we profiled histone modification patterns in aortic tissues during AAA formation in two distinct mouse models; (1) angiotensin II (AngII) infusion in low density lipoprotein receptor (LDLR) knockout (KO) mice, and (2) calcium chloride (CaCl 2 ) application in wild type mice. Methods and Results:AAA formed in both models, in conjunction with enhanced macrophage infiltration, elastin degradation and matrix metalloproteinases expression as evaluated by immunohistochemistry. To investigate the histone modification patterns during AAA formation, total histone proteins were extracted from AAA tissues, and histone H3 modifications were quantified using profiling kits. Intriguingly, we observed dynamic changes in histone H3 modifications of lysine (K) residues at different time points during AAA formation. In mature aneurysmal tissues at 3 weeks after AngII infusion, we detected reduced K4/K27/K36 monomethylation, K9 trimethylation K9, and K9/K56 acetylation (<70%), and increased K4 trimethylation (>130%). Conversely, in CaCl 2 -induced AAA, K4/K9/K27/K36/K79 monomethylation and K9/K18/K56 acetylation were reduced in AAA tissues, whereas K27 di-/tri-methylation and K14 acetylation were upregulated. Interestingly, K4/K27/K36 monomethylation, K9 trimethylation, and K9/K56 acetylation were commonly downregulated in both animal models, while no H3 modifications were uniformly upregulated. Western blot of AAA tissues confirmed Greenway et al.Profiling of Histone H3 Modifications in AAA markedly reduced levels of key H3 modifications, including H3K4me1, H3K9me3, and H3K56ac. Furthermore, pathway enrichment analysis using an integrative bioinformatics approach identified specific molecular pathways, including endocytosis, exon guidance and focal adhesion signaling, that may potentially be linked to these histone H3 modifications during AAA formation.Conclusions: Dynamic modifications of histone H3 occur during AAA formation in both animal models. We identified 6 discreet H3 modifications that are consistently downregulated in both models, suggesting a possible role in AAA pathobiology. Identifying the functional mechanisms may facilitate development of novel strategies for AAA prevention or treatment.

Obesity is a major risk factor for both metabolic and cardiovascular disease. We reported that, in obese male mice, histone deacetylase 9 (HDAC9) is upregulated in adipose tissues, and global deletion of HDAC9 protected against high fat diet (HFD)-induced obesity and metabolic disease. Here, we investigated the impact of adipocyte-specific HDAC9 gene deletion on diet-induced obesity in male and female mice. The HDAC9 gene expression was increased in adipose tissues of obese male and female mice and HDAC9 expression correlated positively with body mass index in humans. Interestingly, female, but not male, adipocyte-specific HDAC9 KO mice on HFD exhibited reduced body weight and visceral adipose tissue mass, adipocyte hypertrophy, and improved insulin sensitivity, glucose tolerance and adipogenic differentiation gene expression. Furthermore, adipocyte-specific HDAC9 gene deletion in female mice improved metabolic health as assessed by whole body energy expenditure, oxygen consumption, and adaptive thermogenesis. Mechanistically, compared to female mice, HFD-fed male mice exhibited preferential HDAC9 expression in the stromovascular fraction, which may have offset the impact of adipocyte-specific HDAC9 gene deletion in male mice. These results suggest that HDAC9 expressed in adipocytes is detrimental to obesity in female mice and provides novel evidence of sex-related differences in HDAC9 cellular expression and contribution to obesity-related metabolic disease.

Background Senescence is a state associated with aging and obesity in which cells stop replicating. It has recently been shown that elimination of senescent cells by senolytic therapy can extend health and lifespan in mice. Our previous studies showed that global histone deacetylase 9 (HDAC9) gene deletion protected mice against obesity‐associated metabolic disorder. Here, we hypothesized that HDAC9 expression during aging plays an important role in the development of adipose tissue senescence. Methods and Results Adipose tissue from 20‐month old wild type mice showed increased expression of HDAC9 (2 fold) and senescence markers, p16 (5 fold) and p21 (2 fold) compared to 3‐month old mice, as examined by qRT‐PCR. Furthermore, HDAC9 expression in human subcutaneous adipose tissue positively correlated with age (r2=0.088, p=0.034). Intriguingly, adipose tissues from HDAC9 knockout (KO) mice exhibited reduced levels of senescence‐associated beta‐galactosidase (SABG) staining and lower expression of p16 and p21 (0.4 fold and 0.2 fold, respectively). Preadipocytes reside in adipose tissue and replenish aged or dying adipocytes, thus playing an important role in regulating adipose tissue health and senescence. Interestingly, reduced SABG staining was also observed in early passage primary preadipocyte culture derived from HDAC9 KO adipose tissue as compared to WT (17% vs 30% SABG+). Furthermore, we found that HDAC9 KO primary preadipocytes were resistant to senescence‐inducing stimuli such as H2O2 treatment or UV light exposure as evaluated by senescent marker expression. Next, we measured adipose tissue mitochondrial function which is mechanistically linked to cellular senescence. Interestingly, HDAC9 gene deletion significantly increased adipose tissue mitochondrial oxygen consumption rate (e.g. increased basal and maximal respiration, greater proton leak and ATP production) in adipose tissue, as measured by the Seahorse Analyzer. Conclusion HDAC9 plays a crucial role in the development of adipose tissue senescence, possibly through regulating mitochondrial function, and thus, HDAC9 may be a promising target to combat the development of a senescent phenotype and to maintain healthy adipose tissue.

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Introduction: Saphenous veins (SVs) are frequently used in CABG surgery, but over 50% of the SV grafts fail in the first 10 years after surgery due to neointima formation. Long non-coding RNAs (lncRNAs) have emerged as attractive therapeutic targets and biomarkers for cardiovascular disease. However, studies on their role and mechanisms in humans are limited. This study aimed to unravel epigenetic mechanisms of neointima formation in human SVs and investigate the role of candidate lncRNAs in key vascular cell functions pertinent to neointima formation. Methods and Results: By using an ex vivo model of human SV graft disease wherein segments of human SV are incubated in tissue culture, we performed RNA-sequencing on human SV with and without neointima formation to interrogate the global transcriptomic changes, and determined 699 differentially expressed novel lncRNAs during neointimal formation. We then identified BAZ1A-antisense (AS)1 as a novel lncRNA highly upregulated during neointima formation. BAZ1A-AS1 overlaps antisense to its cis- regulatory gene, BAZ1A , which was reported to play a role in oxidative stress and DNA damage repair response. We found that one isoform of BAZ1A-AS1 primarily localizes to the nucleus of VSMCs. Interestingly, UV exposure of vascular smooth muscle cells (VSMCs) isolated from human SV induced significant upregulation of BAZ1A and BAZ1A-AS1, suggesting that BAZ1A-AS1 could be associated with chromatin repair processes activated during neointima formation. To investigate whether BAZ1A-AS1 can regulate VSMC functions pertinent to neointima formation, VSMCs were transfected with BAZ1A-AS1 antisense gapmers. Knockdown of BAZ1A-AS1 showed reduced cell proliferation and migration, and increased cell death and DNA damage in VSMCs. Furthermore, role of BAZ1A during neointima formation in vivo is currently under investigation in a carotid artery ligation model using BAZ1A knockout mice. Conclusions: We identified BAZ1A-AS1 as a novel lncRNA associated with neointima formation in human SV, and targeted inhibition of BAZ1A-AS1 or its cis-regulator gene BAZ1A could be a promising strategy for SV graft disease.