Sirt6 mediates antioxidative functions by increasing Nrf2 abundance.

Oxidative stress caused by excess ROS often leads to cellular macromolecule damage and eventually causes various biological catastrophes. Sirt6, a member of the mammalian homolog family of yeast Sir2 NAD+-dependent histone deacetylases, regulates multiple biological processes. Sirt6 exerts antioxidative functions by enhancing DNA repair and DNA end resection. In our study, we found that Sirt6 expression was induced by H2O2 and paraquat (PQ) in cells. When exposed to PQ, the Sirt6+/- C57BL/6 mice showed more serious liver damage and lower survival rate than the Sirt6+/+ mice. The Nrf2 protein levels and the mRNA levels of its target genes in mouse tissues were decreased by Sirt6 deficiency, and Sirt6 overexpression increased the Nrf2 protein content. Moreover, the endogenous H2O2 levels were increased in the tissues of Sirt6-deficient mice and were decreased in Sirt6 overexpression cells. Then, we found that Nrf2 was degraded faster in the Sirt6-deficient mouse embryonic fibroblasts (MEFs) than in the wild type MEFs and that Sirt6 enhanced the protein accumulation of Nrf2 in the nucleus. Lastly, we found that Sirt6 interacted with Nrf2 in co-IP and GST pull-down assays and that Sirt6 overexpression decreased the binding of Nrf2 to Keap1. Taken together, the results of the present study suggest that Sirt6 exerts antioxidative functions by increasing the Nrf2 protein level via Keap1-mediated regulation.

Copper-catalyzed ring-opening trifluoromethylthiolation/trifluoromethylselenolation of cyclopropanols with TsSCF3 or Se-(trifluoromethyl) 4-methoxybenzenesulfonoselenoate.

We report a ring-opening trifluoromethylthiolation of cyclopropanols with TsSCF3 by using Cu(OAc)2 as the catalyst. Moreover, by using this strategy, the trifluoromethylselenolation of cyclopropanols with Se-(trifluoromethyl) 4-methoxybenzenesulfonoselenoate to access ß-SeCF3-substituted carbonyl compounds is achieved for the first time. The broad substrate scope, readily accessible reagents and cheap catalyst make this protocol an alternative and efficient method for the synthesis of ß-SCF3-substituted or ß-SeCF3-substituted carbonyl compounds.

SIRT2 Acts as a Cardioprotective Deacetylase in Pathological Cardiac Hypertrophy.

BACKGROUND: Pathological cardiac hypertrophy induced by stresses such as aging and neurohumoral activation is an independent risk factor for heart failure and is considered a target for the treatment of heart failure. However, the mechanisms underlying pathological cardiac hypertrophy remain largely unknown. We aimed to investigate the roles of SIRT2 in aging-related and angiotensin II (Ang II)-induced pathological cardiac hypertrophy. METHODS: Male C57BL/6J wild-type and Sirt2 knockout mice were subjected to the investigation of aging-related cardiac hypertrophy. Cardiac hypertrophy was also induced by Ang II (1.3 mg/kg/d for 4 weeks) in male C57BL/6J Sirt2 knockout mice, cardiac-specific SIRT2 transgenic (SIRT2-Tg) mice, and their respective littermates (8 to ≈12 weeks old). Metformin (200 mg/kg/d) was used to treat wild-type and Sirt2 knockout mice infused with Ang II. Cardiac hypertrophy, fibrosis, and cardiac function were examined in these mice. RESULTS: SIRT2 protein expression levels were downregulated in hypertrophic hearts from mice. Sirt2 knockout markedly exaggerated cardiac hypertrophy and fibrosis and decreased cardiac ejection fraction and fractional shortening in aged (24-month-old) mice and Ang II-infused mice. Conversely, cardiac-specific SIRT2 overexpression protected the hearts against Ang II-induced cardiac hypertrophy and fibrosis and rescued cardiac function. Mechanistically, SIRT2 maintained the activity of AMP-activated protein kinase (AMPK) in aged and Ang II-induced hypertrophic hearts in vivo as well as in cardiomyocytes in vitro. We identified the liver kinase B1 (LKB1), the major upstream kinase of AMPK, as the direct target of SIRT2. SIRT2 bound to LKB1 and deacetylated it at lysine 48, which promoted the phosphorylation of LKB1 and the subsequent activation of LKB1-AMPK signaling. Remarkably, the loss of SIRT2 blunted the response of AMPK to metformin treatment in mice infused with Ang II and repressed the metformin-mediated reduction of cardiac hypertrophy and protection of cardiac function. CONCLUSIONS: SIRT2 promotes AMPK activation by deacetylating the kinase LKB1. Loss of SIRT2 reduces AMPK activation, promotes aging-related and Ang II-induced cardiac hypertrophy, and blunts metformin-mediated cardioprotective effects. These findings indicate that SIRT2 will be a potential target for therapeutic interventions in aging- and stress-induced cardiac hypertrophy.

The long noncoding RNA Gm15055 represses Hoxa gene expression by recruiting PRC2 to the gene cluster.

The Hox genes encode transcription factors that determine embryonic pattern formation. In embryonic stem cells, the Hox genes are silenced by PRC2. Recent studies have reported a role for long noncoding RNAs in PRC2 recruitment in vertebrates. However, little is known about how PRC2 is recruited to the Hox genes in ESCs. Here, we used stable knockdown and knockout strategies to characterize the function of the long noncoding RNAGm15055 in the regulation of Hoxa genes in mouse ESCs. We found that Gm15055 is highly expressed in mESCs and its expression is maintained by OCT4.Gm15055 represses Hoxa gene expression by recruiting PRC2 to the cluster and maintaining the H3K27me3 modification on Hoxa promoters. A chromosome conformation capture assay revealed the close physical association of the Gm15055 locus to multiple sites at the Hoxa gene cluster in mESCs, which may facilitate the in cis targeting of Gm15055RNA to the Hoxa genes. Furthermore, an OCT4-responsive positive cis-regulatory element is found in the Gm15055 gene locus, which potentially regulates both Gm15055 itself and the Hoxa gene activation. This study suggests how PRC2 is recruited to the Hoxa locus in mESCs, and implies an elaborate mechanism for Hoxa gene regulation in mESCs.

SIRT4 accelerates Ang II-induced pathological cardiac hypertrophy by inhibiting manganese superoxide dismutase activity.

AIMS: Oxidative stress contributes to the development of cardiac hypertrophy and heart failure. One of the mitochondrial sirtuins, Sirt4, is highly expressed in the heart, but its function remains unknown. The aim of the present study was to investigate the role of Sirt4 in the pathogenesis of pathological cardiac hypertrophy and the molecular mechanism by which Sirt4 regulates mitochondrial oxidative stress. METHODS AND RESULTS: Male C57BL/6 Sirt4 knockout mice, transgenic (Tg) mice exhibiting cardiac-specific overexpression of Sirt4 (Sirt4-Tg) and their respective controls were treated with angiotensin II (Ang II, 1.1 mg/kg/day). At 4 weeks, hypertrophic growth of cardiomyocytes, fibrosis and cardiac function were analysed. Sirt4 deficiency conferred resistance to Ang II infusion by significantly suppressing hypertrophic growth, and the deposition of fibrosis. In Sirt4-Tg mice, aggravated hypertrophy and reduced cardiac function were observed compared with non-Tg mice following Ang II treatment. Mechanistically, Sirt4 inhibited the binding of manganese superoxide dismutase (MnSOD) to Sirt3, another member of the mitochondrial sirtuins, and increased MnSOD acetylation levels to reduce its activity, resulting in elevated reactive oxygen species (ROS) accumulation upon Ang II stimulation. Furthermore, inhibition of ROS with manganese 5, 10, 15, 20-tetrakis-(4-benzoic acid) porphyrin, a mimetic of SOD, blocked the Sirt4-mediated aggravation of the hypertrophic response in Ang II-treated Sirt4-Tg mice. CONCLUSIONS: Sirt4 promotes hypertrophic growth, the generation of fibrosis and cardiac dysfunction by increasing ROS levels upon pathological stimulation. These findings reveal a role of Sirt4 in pathological cardiac hypertrophy, providing a new potential therapeutic strategy for this disease.

PML4 facilitates erythroid differentiation by enhancing the transcriptional activity of GATA-1.

Promyelocytic leukemia protein (PML) has been implicated as a participant in multiple cellular processes including senescence, apoptosis, proliferation, and differentiation. Studies of PML function in hematopoietic differentiation previously focused principally on its myeloid activities and also indicated that PML is involved in erythroid colony formation. However, the exact role that PML plays in erythropoiesis is essentially unknown. In this report, we found that PML4, a specific PML isoform expressed in erythroid cells, promotes endogenous erythroid genes expression in K562 and primary human erythroid cells. We show that the PML4 effect is GATA binding protein 1 (GATA-1) dependent using GATA-1 knockout/rescued G1E/G1E-ER4 cells. PML4, but not other detected PML isoforms, directly interacts with GATA-1 and can recruit it into PML nuclear bodies. Furthermore, PML4 facilitates GATA-1 trans-activation activity in an interaction-dependent manner. Finally, we present evidence that PML4 enhances GATA-1 occupancy within the globin gene cluster and stimulates cooperation between GATA-1 and its coactivator p300. These results demonstrate that PML4 is an important regulator of GATA-1 and participates in erythroid differention by enhancing GATA-1 trans-activation activity.

Sox2 Deacetylation by Sirt1 Is Involved in Mouse Somatic Reprogramming.

Mouse somatic cells can be reprogrammed into induced pluripotent stem cells by defined factors known to regulate pluripotency, including Oct4, Sox2, Klf4, and c-Myc. Together with Oct4, Sox2 plays a major role as a master endogenous pluripotent genes trigger in reprogramming. It has been reported that Sirtuin 1 (Sirt1), a member of the Sirtuin family of NAD(+) -dependent protein deacetylases, is involved in embryonic stem cell antioxidation, differentiation, and individual development. However, as a deacetylation enzyme, whether Sirt1 influences reprogramming through its post-translational modification function remains unknown. In this study, we provide evidence that deacetylation of Sox2 by Sirt1 is required for reprogramming. We found that a low level of Sox2 acetylation could significantly increase reprogramming efficiency. Furthermore, we found that Sox2 can be deacetylated by Sirt1 in an Oct4-mediated manner. Compared with wild-type cells, Sirt1-null mouse embryonic fibroblasts exhibit decreased reprogramming efficiency, and overexpression of Sirt1 rescues this defect. In addition, Sirt1 functions in the regulation of reprogramming through deacetylating Sox2. Taken together, we have identified a new regulatory role of Sirt1 in reprogramming and provided a link between deacetylation events and somatic cell reprogramming. Stem Cells 2015;33:2135-2147.

SIRT1 deacetylates SATB1 to facilitate MAR HS2-MAR ε interaction and promote ε-globin expression.

The higher order chromatin structure has recently been revealed as a critical new layer of gene transcriptional control. Changes in higher order chromatin structures were shown to correlate with the availability of transcriptional factors and/or MAR (matrix attachment region) binding proteins, which tether genomic DNA to the nuclear matrix. How posttranslational modification to these protein organizers may affect higher order chromatin structure still pending experimental investigation. The type III histone deacetylase silent mating type information regulator 2, S. cerevisiae, homolog 1 (SIRT1) participates in many physiological processes through targeting both histone and transcriptional factors. We show that MAR binding protein SATB1, which mediates chromatin looping in cytokine, MHC-I and ß-globin gene loci, as a new type of SIRT1 substrate. SIRT1 expression increased accompanying erythroid differentiation and the strengthening of ß-globin cluster higher order chromatin structure, while knockdown of SIRT1 in erythroid k562 cells weakened the long-range interaction between two SATB1 binding sites in the ß-globin locus, MAR(HS2) and MAR(ε). We also show that SIRT1 activity significantly affects ε-globin gene expression in a SATB1-dependent manner and that knockdown of SIRT1 largely blocks ε-globin gene activation during erythroid differentiation. Our work proposes that SIRT1 orchestrates changes in higher order chromatin structure during erythropoiesis, and reveals the dynamic higher order chromatin structure regulation at posttranslational modification level.

Schlafen 11 triggers innate immune responses through its ribonuclease activity upon detection of single-stranded DNA.

Nucleic acids are major structures detected by the innate immune system. Although intracellular single-stranded DNA (ssDNA) accumulates during pathogen infection or disease, it remains unclear whether and how intracellular ssDNA stimulates the innate immune system. Here, we report that intracellular ssDNA triggers cytokine expression and cell death in a CGT motif-dependent manner. We identified Schlafen 11 (SLFN11) as an ssDNA-activated RNase, which is essential for the innate immune responses induced by intracellular ssDNA and adeno-associated virus infection. We found that SLFN11 directly binds ssDNA containing CGT motifs through its carboxyl-terminal domain, translocates to the cytoplasm upon ssDNA recognition, and triggers innate immune responses through its amino-terminal ribonuclease activity that cleaves transfer RNA (tRNA). Mice deficient in Slfn9, a mouse homolog of SLFN11, exhibited resistance to CGT ssDNA-induced inflammation, acute hepatitis, and septic shock. This study identifies CGT ssDNA and SLFN11/9 as a class of immunostimulatory nucleic acids and pattern recognition receptors, respectively, and conceptually couples DNA immune sensing to controlled RNase activation and tRNA cleavage.

Enhancing homology-directed repair efficiency with HDR-boosting modular ssDNA donor.

Despite the potential of small molecules and recombinant proteins to enhance the efficiency of homology-directed repair (HDR), single-stranded DNA (ssDNA) donors, as currently designed and chemically modified, remain suboptimal for precise gene editing. Here, we screen the biased ssDNA binding sequences of DNA repair-related proteins and engineer RAD51-preferred sequences into HDR-boosting modules for ssDNA donors. Donors with these modules exhibit an augmented affinity for RAD51, thereby enhancing HDR efficiency across various genomic loci and cell types when cooperated with Cas9, nCas9, and Cas12a. By combining with an inhibitor of non-homologous end joining (NHEJ) or the HDRobust strategy, these modular ssDNA donors achieve up to 90.03% (median 74.81%) HDR efficiency. The HDR-boosting modules targeting an endogenous protein enable a chemical modification-free strategy to improve the efficacy of ssDNA donors for precise gene editing.

SIRT1 mediates the protective function of Nkx2.5 during stress in cardiomyocytes.

Nkx2.5 plays protective roles in cardiac homeostasis and survival in the postnatal hearts. However, the underlying molecular mechanisms that mediate the protective functions of Nkx2.5 remain unknown. Here, we showed that Nkx2.5 was downregulated in response to various stresses and was required for protection against the stress-induced apoptosis of cardiomyocytes. SIRT1, a member of the sirtuin family of proteins, was found to be a direct transcriptional target of Nkx2.5 and was required for the Nkx2.5-mediated protection of cardiomyocytes from doxorubicin (DOX)-induced apoptosis. Moreover, using chromatin immunoprecipitation assays, we found that Nkx2.5 was able to bind to the SIRT1 promoter and that this binding was significantly decreased in DOX-treated mouse hearts. Furthermore, the cardiac-specific overexpression of SIRT1 decreased the DOX-induced apoptosis of cardiomyocytes in SIRT1 transgenic mouse hearts compared with the hearts of their wild-type littermates. These findings demonstrate that SIRT1 acts as a direct transcriptional target of Nkx2.5 that maintains cardiomyocyte homeostasis and survival.

SIRT6 is an epigenetic repressor of thoracic aortic aneurysms via inhibiting inflammation and senescence.

Thoracic aortic aneurysms (TAAs) develop asymptomatically and are characterized by dilatation of the aorta. This is considered a life-threating vascular disease due to the risk of aortic rupture and without effective treatments. The current understanding of the pathogenesis of TAA is still limited, especially for sporadic TAAs without known genetic mutation. Sirtuin 6 (SIRT6) expression was significantly decreased in the tunica media of sporadic human TAA tissues. Genetic knockout of Sirt6 in mouse vascular smooth muscle cells accelerated TAA formation and rupture, reduced survival, and increased vascular inflammation and senescence after angiotensin II infusion. Transcriptome analysis identified interleukin (IL)-1ß as a pivotal target of SIRT6, and increased IL-1ß levels correlated with vascular inflammation and senescence in human and mouse TAA samples. Chromatin immunoprecipitation revealed that SIRT6 bound to the Il1b promoter to repress expression partly by reducing the H3K9 and H3K56 acetylation. Genetic knockout of Il1b or pharmacological inhibition of IL-1ß signaling with the receptor antagonist anakinra rescued Sirt6 deficiency mediated aggravation of vascular inflammation, senescence, TAA formation and survival in mice. The findings reveal that SIRT6 protects against TAA by epigenetically inhibiting vascular inflammation and senescence, providing insight into potential epigenetic strategies for TAA treatment.

Positive regulation of hepatic miR-122 expression by HNF4α.

BACKGROUND & AIMS: miR-122 is the most abundant microRNA in the liver and regulates metabolic pathways including cholesterol biosynthesis, fatty acid synthesis, and oxidation. However, little is known about mechanisms that regulate the expression of miR-122 in the liver. The aim of this study was to identify key transcriptional regulators for miR-122 expression through intensively studying its primary transcript and promoter region. METHODS: Bioinformatics analysis, Northern blotting, RT-PCR, and 5'/3' RACE were performed to analyze miR-122 primary transcript structure, its promoter region, and potential transacting factor binding sites. Reporter gene assays integrated with truncation and site-mutation in miR-122 promoter were performed to determine the trans-activation effect of HNF4α to miR-122-promoter in vitro. ChIP and EMSA assays were performed to determine HNF4α binding to miR-122 promoter. Finally, forced expression and RNAi were performed to verify the regulatory roles of HNF4 to miR-122 expression in vitro and in vivo. RESULTS: Here, we show that miR-122 is processed from a long spliced primary transcript directed by a distal upstream promoter region conserved across species. We dissected this promoter region and identified putative binding sites for liver-enriched transcriptional factors that contribute to the regulation of miR-122 expression, including a putative binding site for hepatocyte nuclear factor 4α (HNF4α). We demonstrate that HNF4α binds to the miR-122 promoter region through the conserved DR-I element. We observed the DR-1-element-dependent activation effect of HNF4α on the conserved miR-122 promoter and the activation could be further enhanced by the addition of PGC1α. Using overexpression and knockdown strategies, we show that HNF4α positively regulates miR122 expression in both Huh7 cells and the mouse liver. CONCLUSIONS: Our results suggest that HNF4α is a key regulator of miR-122 expression in the liver.

Target gene therapy of glioma: overexpression of BAX gene under the control of both tissue-specific promoter and hypoxia-inducible element.

Glioma-specific transcription of tumor-killing genes has been exploited as a promising gene therapeutic modality in glioma patients. Musashi1 (Msi1) and GFAP gene promoters are both cancer-specific promoters. Optimized HIF-binding site (optHBS) sequence was newly found as efficient as EPO HREs used as enhancer in cancer gene therapy. We constructed 4optHBS-Msi1/GFAP promoters and tested their ability to mediate BAX expression to induce apoptosis in glioma cell lines. Our results demonstrated that 4optHBS-Msi1/GFAP promoters are apparently strong and glioma-selective promoters with potential application in targeted glioma gene therapy, and 4optHBS-Msi1/GFAPBAXa are valuable tools for glioma gene therapy.

Diurnal oscillations of endogenous H2O2 sustained by p66Shc regulate circadian clocks.

Redox balance, an essential feature of healthy physiological steady states, is regulated by circadian clocks, but whether or how endogenous redox signalling conversely regulates clockworks in mammals remains unknown. Here, we report circadian rhythms in the levels of endogenous H2O2 in mammalian cells and mouse livers. Using an unbiased method to screen for H2O2-sensitive transcription factors, we discovered that rhythmic redox control of CLOCK directly by endogenous H2O2 oscillations is required for proper intracellular clock function. Importantly, perturbations in the rhythm of H2O2 levels induced by the loss of p66Shc, which oscillates rhythmically in the liver and suprachiasmatic nucleus (SCN) of mice, disturb the rhythmic redox control of CLOCK function, reprogram hepatic transcriptome oscillations, lengthen the circadian period in mice and modulate light-induced clock resetting. Our findings suggest that redox signalling rhythms are intrinsically coupled to the circadian system through reversible oxidative modification of CLOCK and constitute essential mechanistic timekeeping components in mammals.

Caloric Restriction Induces MicroRNAs to Improve Mitochondrial Proteostasis.

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 (UPRmt), 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 UPRmt to improve mitochondrial proteostasis.

MafK/NF-E2 p18 is required for beta-globin genes activation by mediating the proximity of LCR and active beta-globin genes in MEL cell line.

Evidences indicate that locus control region (LCR) of beta-globin spatially closes to the downstream active gene promoter to mediate the transcriptional activation by looping. DNA binding proteins may play an important role in the looping formation. NF-E2 is one of the key transcription factors in beta-globin gene transcriptional activation. To shed light on whether NF-E2 is involved in this process, DS19MafKsiRNA cell pools were established by specifically knocked down the expression of MafK/NF-E2 p18, one subunit of NF-E2 heterodimer. In the above cell pools, it was observed that the occupancy efficiency of NF-E2 on beta-globin gene locus and the expression level of beta-globin genes were decreased. H3 acetylation, H3-K4 methylation and the deposition of RNA polymerase II, but not the recruitment of GATA-1, were also found reduced at the beta-globin gene cluster. Chromosome Conformation Capture (3C) assay showed that the cross-linking frequency between the main NF-E2 binding site HS2 and downstream structural genes was reduced compared to the normal cell. This result demonstrated that MafK/NF-E2 p18 recruitment was involved in the physical proximity of LCR and active beta-globin genes upon beta-globin gene transcriptional activation.

Improvement of SSO-mediated gene repair efficiency by nonspecific oligonucleotides.

Targeted gene repair mediated by single-stranded DNA oligonucleotides (SSOs) is a promising method to correct the mutant gene precisely in prokaryotic and eukaryotic systems. We used a HeLa cell line, which was stably integrated with mutant enhanced green fluorescence protein gene (mEGFP) in the genome, to test the efficiency of SSO-mediated gene repair. We found that the mEGFP gene was successfully repaired by specific SSOs, but the efficiency was only approximately 0.1%. Then we synthesized a series of nonspecific oligonucleotides, which were single-stranded DNA with different lengths and no significant similarity with the SSOs. We found the efficiency of SSO-mediated gene repair was increased by 6-fold in nonspecific oligonucleotides-treated cells. And this improvement in repair frequency correlated with the doses of the nonspecific oligonucleotides, instead of the lengths. Our evidence suggested that this increased repair efficiency was achieved by the transient alterations of the cellular proteome. We also found the obvious strand bias that antisense SSOs were much more effective than sense SSOs in the repair experiments with nonspecific oligonucleotides. These results provide a fresh clue into the mechanism of SSO-mediated targeted gene repair in mammalian cells.

Mouse macrophage specific knockout of SIRT1 influences macrophage polarization and promotes angiotensin II-induced abdominal aortic aneurysm formation.

Abdominal aortic aneurysm (AAA) is a vascular degenerative disease. Macrophage polarization and the balance between classically activated macrophages (M1) and alternatively activated macrophages (M2) are crucial for AAA pathogenesis. The present study aims to investigate the roles of macrophage SIRT1 in AAA formation and macrophage polarization. We found that in mouse peritoneal macrophages, SIRT1 expression was decreased after M1 stimulation, but was enhanced after M2 stimulation. Results from SIRT1flox/flox mice and macrophage specific SIRT1 knockout mice with treatment of angiotensin II (Ang II) for 4 weeks showed that macrophage specific deficiency of SIRT1 increased the incidence of AAA and exacerbated the severity, including more severe aneurysm types, enlarged diameter of the aneurysm and increased degradation of elastin. In mouse aortas, SIRT1 deficiency increased the pro-inflammatory M1 molecule inducible nitric oxide synthase (iNOS), and decreased M2 molecules such as arginase 1 (Arg1) and mannose receptor (MR). Furthermore, in peritoneal macrophages, SIRT1 deficiency increased the expression of M1 inflammatory molecules, but decreased the expression of M2 molecules. Overexpression of SIRT1 had the opposite effects. Thus, macrophage specific knockout of SIRT1 influences macrophage polarization and accelerates Ang II-induced AAA formation.