Deacetylase-independent function of SIRT6 couples GATA4 transcription factor and epigenetic activation against cardiomyocyte apoptosis

Epigenetic regulation of diverse regulated cell death modalities in cardiovascular disease: Insights into necroptosis, pyroptosis, ferroptosis, and cuproptosis

Cell death constitutes a critical component of the pathophysiology of cardiovascular diseases. A growing array of non-apoptotic forms of regulated cell death (RCD)-such as necroptosis, ferroptosis, pyroptosis, and cuproptosis-has been identified and is intimately linked to various cardiovascular conditions. These forms of RCD are governed by genetically programmed mechanisms within the cell, with epigenetic modifications being a common and crucial regulatory method. Such modifications include DNA methylation, RNA methylation, histone methylation, histone acetylation, and non-coding RNAs. This review recaps the roles of DNA methylation, RNA methylation, histone modifications, and non-coding RNAs in cardiovascular diseases, as well as the mechanisms by which epigenetic modifications regulate key proteins involved in cell death. Furthermore, we systematically catalog the existing epigenetic pharmacological agents targeting novel forms of RCD and their mechanisms of action in cardiovascular diseases. This article aims to underscore the pivotal role of epigenetic modifications in precisely regulating specific pathways of novel RCD in cardiovascular diseases, thus offering potential new therapeutic avenues that may prove more effective and safer than traditional treatments.

Follistatin-like 1 protects against doxorubicin-induced cardiotoxicity by preventing mitochondrial dysfunction through the SIRT6/Nrf2 signaling pathway

Mitochondrial dysfunction and myocardial remodeling have been reported to be the main underlying molecular mechanisms of doxorubicin-induced cardiotoxicity. SIRT6 is a nicotinamide adenine dinucleotide-dependent enzyme that plays a vital role in cardiac protection against various stresses. Moreover, previous studies have demonstrated that FSTL1 could alleviate doxorubicin-induced cardiotoxicity by inhibiting autophagy. The present study investigated the probable mechanisms of FSTL1 on doxorubicin-induced cardiotoxicity in vivo and in vitro. We confirmed that FSTL1 exerted a pivotal protective role on cardiac tissue in vivo and on doxorubicin-induced cell injury in vitro. Furthermore, FSTL1 can alleviate doxorubicin-induced mitochondrial dysfunction by inhibiting autophagy and apoptosis. Further studies demonstrated that FSTL1 can activate SIRT6 signaling by restoring the SIRT6 protein expression in doxorubicin-induced myocardial injury. SIRT6 activation elevated the protein expression of Nrf2 in doxorubicin-induced H9C2 injury. Treatment with the Nrf2 inhibitor ML385 partially antagonized the cardioprotective role of SIRT6 on doxorubicin-induced autophagy or apoptosis. These results suggested that the protective mechanism of FSTL1 on doxorubicin-induced cardiotoxicity may be related with the inhibition of autophagy and apoptosis, partly through the activation of SIRT6/Nrf2.

The role and mechanism of epigenetics in anticancer drug-induced cardiotoxicity

Cardiovascular disease is the main factor contributing to the global burden of diseases, and the cardiotoxicity caused by anticancer drugs is an essential component that cannot be ignored. With the development of anticancer drugs, the survival period of cancer patients is prolonged; however, the cardiotoxicity caused by anticancer drugs is becoming increasingly prominent. Currently, cardiovascular disease has emerged as the second leading cause of mortality among long-term cancer survivors. Anticancer drug-induced cardiotoxicity has become a frontier and hot topic. The discovery of epigenetics has given the possibility of environmental changes in gene expression, protein synthesis, and traits. It has been found that epigenetics plays a pivotal role in promoting cardiovascular diseases, such as heart failure, coronary heart disease, and hypertension. In recent years, increasing studies have underscored the crucial roles played by epigenetics in anticancer drug-induced cardiotoxicity. Here, we provide a comprehensive overview of the role and mechanisms of epigenetics in anticancer drug-induced cardiotoxicity.

The transcription factor GATA6 accelerates vascular smooth muscle cell senescence-related arterial calcification by counteracting the role of anti-aging factor SIRT6 and impeding DNA damage repair

Arterial calcification is a hallmark of vascular pathology in the elderly and in individuals with chronic kidney disease (CKD). Vascular smooth muscle cells (VSMCs), after attaining a senescent phenotype, are implicated in the calcifying process. However, the underlying mechanism remains to be elucidated. Here, we reveal an aberrant upregulation of transcriptional factor GATA6 in the calcified aortas of humans, mice with CKD and mice subjected to vitamin D3 injection. Knockdown of GATA6, via recombinant adeno-associated virus carrying GATA6 shRNA, inhibited the development of arterial calcification in mice with CKD. Further gain- and loss-of function experiments in vitro verified the contribution of GATA6 in osteogenic differentiation of VSMCs. Samples of human aorta exhibited a positive relationship between age and GATA6 expression and GATA6 was also elevated in the aortas of old as compared to young mice. Calcified aortas displayed senescent features with VSMCs undergoing premature senescence, blunted by GATA6 downregulation. Notably, abnormal induction of GATA6 in senescent and calcified aortas was rescued in Sirtuin 6 (SIRT6)-transgenic mice, a well-established longevity mouse model. Suppression of GATA6 accounted for the favorable effect of SIRT6 on VSMCs senescence prevention. Mechanistically, SIRT6 inhibited the transcription of GATA6 by deacetylation and increased degradation of transcription factor Nkx2.5. Moreover, GATA6 was induced by DNA damage stress during arterial calcification and subsequently impeded the Ataxia-telangiectasia mutated (ATM)-mediated DNA damage repair process, leading to accelerated VSMCs senescence and osteogenic differentiation. Thus, GATA6 is a novel regulator in VSMCs senescence. Our findings provide novel insight in arterial calcification and a potential new target for intervention.

A bibliometric analysis of cardiomyocyte apoptosis from 2014 to 2023: A review

Cardiomyocyte apoptosis is an important factor in cardiac function decline observed in various cardiovascular diseases. To understand the progress in the field of cardiomyocyte apoptosis research, this paper uses bibliometrics to statistically analyze publications in this field. A total of 5939 articles were retrieved from the core Web of Science database, and then VOSviewer and Citespace were used to conduct a scientometric analysis of the authors, countries, institutions, references and keywords included in the articles to determine the cooperative relationships between researchers that study cardiomyocyte apoptosis. At present, the research hotspots in this field mainly include experimental research, molecular mechanisms, pathophysiology and cardiac regeneration of cardiomyocyte apoptosis-related diseases. NOD-like receptor thermal protein domain associated protein 3 inflammasome, circular RNA, and sepsis are the research frontiers in this field and are emerging as new areas of research focus. This work provides insight into research directions and the clinical application value for the continued advancement of cardiomyocyte apoptosis research.

Oridonin ameliorates doxorubicin induced-cardiotoxicity via the E2F1/Sirt6/PGC1α pathway in mice

Doxorubicin induced cardiotoxicity (DIC) arises from mitochondrial dysfunction and oxidative stress. Oridonin (Ori), a natural tetracycline diterpenoid, has shown cardiac protective effect; however, its role in DIC remains unclear. This study investigates the protective effect of Ori against DIC and elucidates its underlying molecular mechanisms. The results demonstrate that Ori significantly alleviated DIC by improving myocardial structure, reducing the proportion of apoptotic cells, and alleviating the myocardial oxidative damage and mitochondrial dysfunction both in vivo and in vitro. Doxorubicin significantly decreased Sirt6 and PGC1α levels in cardiac tissues, which was reversed by Ori. Furthermore, Sirt6 overexpression significantly improved myocardial structure and reduced the proportion of apoptotic cells by reducing oxidative stress and improving mitochondrial function. The protective effect of Ori is neutralized by the Sirt6 inhibitor OSS_128167, evidenced by downregulated mRNA and protein expression of PGC1α. The transcription factor E2F1 was upregulated by doxorubicin, leading to decreased Sirt6 expression-an effect mitigated by Ori. Molecular docking simulations indicate direct binding between Ori and specific amino acid residues on E2F1 through hydroxyl bonds. These findings uncover a novel mechanism whereby Ori attenuates DIC by modulating the E2F1/Sirt6/PGC1α pathway.

SIRT6 regulates obesity-induced oxidative stress via ENDOG/SOD2 signaling in the heart

The sirtuin 6 (SIRT6) participates in regulating glucose and lipid homeostasis. However, the function of SIRT6 in the process of cardiac pathogenesis caused by obesity-associated lipotoxicity remains to be unveiled. This study was designed to elucidate the role of SIRT6 in the pathogenesis of cardiac injury due to nutrition overload-induced obesity and explore the downstream signaling pathways affecting oxidative stress in the heart. In this study, we used Sirt6 cardiac-specific knockout murine models treated with a high-fat diet (HFD) feeding to explore the function and mechanism of SIRT6 in the heart tissue during HFD-induced obesity. We also took advantage of neonatal cardiomyocytes to study the role and downstream molecules of SIRT6 during HFD-induced injury in vitro, in which intracellular oxidative stress and mitochondrial content were assessed. We observed that during HFD-induced obesity, Sirt6 loss-of-function aggravated cardiac injury including left ventricular hypertrophy and lipid accumulation. Our results evidenced that upon increased fatty acid uptake, SIRT6 positively regulated the expression of endonuclease G (ENDOG), which is a mitochondrial-resident molecule that plays an important role in mitochondrial biogenesis and redox homeostasis. Our results also showed that SIRT6 positively regulated superoxide dismutase 2 (SOD2) expression post-transcriptionally via ENDOG. Our study gives a new sight into SIRT6 beneficial role in mitochondrial biogenesis of cardiomyocytes. Our data also show that SIRT6 is required to reduce intracellular oxidative stress in the heart triggered by high-fat diet-induced obesity, involving the control of ENDOG/SOD2.

The role of mammalian Sirtuin 6 in cardiovascular diseases and diabetes mellitus

Cardiovascular diseases are severe diseases posing threat to human health because of their high morbidity and mortality worldwide. The incidence of diabetes mellitus is also increasing rapidly. Various signaling molecules are involved in the pathogenesis of cardiovascular diseases and diabetes. Sirtuin 6 (Sirt6), which is a class III histone deacetylase, has attracted numerous attentions since its discovery. Sirt6 enjoys a unique structure, important biological functions, and is involved in multiple cellular processes such as stress response, mitochondrial biogenesis, transcription, insulin resistance, inflammatory response, chromatin silencing, and apoptosis. Sirt6 also plays significant roles in regulating several cardiovascular diseases including atherosclerosis, coronary heart disease, as well as cardiac remodeling, bringing Sirt6 into the focus of clinical interests. In this review, we examine the recent advances in understanding the mechanistic working through which Sirt6 alters the course of lethal cardiovascular diseases and diabetes mellitus.

Tumor microenvironment-responsive spherical nucleic acid nanoparticles for enhanced chemo-immunotherapy

Certain chemotherapeutics can induce tumor cells' immunogenic cell death (ICD), release tumor antigens, and thereby trigger personalized antitumor immune responses. Co-delivery of adjuvants using nanocarriers could amplify the ICD-induced tumor-specific immunity achieving a synergistic chemo-immunotherapeutic effect. However, complicated preparation, low drug loading efficiency, and potential carrier-associated toxicity are the major challenges that limited its clinical applications. Herein, a carrier-free core-shell nanoparticle (MPLA-CpG-sMMP9-DOX, MCMD NPs) was constructed by facile self-assembly of spherical nucleic acids (SNA) with two adjuvants of CpG ODN and monophosphoryl lipid A (MPLA) as a core and doxorubicin (DOX) radially around the dual-adjuvants SNA as a shell. The results demonstrated that MCMD NPs could enhance drugs accumulation in tumors, and release DOX upon enzymatic degradation of matrix metalloproteinase-9 (MMP-9) peptide in the tumor microenvironment (TME), which enhanced the direct-killing effect of DOX on tumor cells. The core of MPLA-CpG SNA efficiently boosted the ICD-induced antitumor immune response to further attack tumor cells. Thus, MCMD NPs achieved a synergistic therapeutic effect of chemo-immunotherapy with reduced off-target toxicity. This study provided an efficient strategy for the development of a carrier-free nano-delivery system for enhanced cancer chemo-immunotherapy.

The Role of Histone Deacetylases in Acute Lung Injury-Friend or Foe

Acute lung injury (ALI), caused by intrapulmonary or extrapulmonary factors such as pneumonia, shock, and sepsis, eventually disrupts the alveolar-capillary barrier, resulting in diffuse pulmonary oedema and microatasis, manifested by refractory hypoxemia, and respiratory distress. Not only is ALI highly lethal, but even if a patient survives, there are also multiple sequelae. Currently, there is no better treatment than supportive care, and we urgently need to find new targets to improve ALI. Histone deacetylases (HDACs) are epigenetically important enzymes that, together with histone acetylases (HATs), regulate the acetylation levels of histones and non-histones. While HDAC inhibitors (HDACis) play a therapeutic role in cancer, inflammatory, and neurodegenerative diseases, there is also a large body of evidence suggesting the potential of HDACs as therapeutic targets in ALI. This review explores the unique mechanisms of HDACs in different cell types of ALI, including macrophages, pulmonary vascular endothelial cells (VECs), alveolar epithelial cells (AECs), and neutrophils.

Sirtuin 6 is a key contributor to gender differences in acute kidney injury

Acute kidney injury (AKI) is rapidly increasing nowadays and at a high risk to progress into chronic kidney disease (CKD). Of note, men are more susceptive to AKI, suggesting gender differences in AKI patients. However, the underlying mechanisms remain largely unclear. To test it, we adopted two experimental models of AKI, including ischemia/reperfusion injury and rhabdomyolysis, which were constructed in age-matched male and female mice. We found severe damages of tubular apoptosis, mitochondrial dysfunction, and loss of renal function showing in male mice, while female mice only had very mild injury. We further tested the expression of Sirtuins, and found that female mice could preserve more Sirtuin members' expression in case of kidney damage. Among Sirtuin family, Sirtuin 6 was maximally preserved in injured kidney in female mice, suggesting its important role involved in the gender differences of AKI pathogenesis. We then found that knockdown of androgen receptor (AR) attenuated tubular damage, mitochondrial dysfunction and retarded the loss of renal function. Overexpression of Sirtuin 6 also showed similar results. Furthermore, in cultured tubular cells, dihydrotestosterone (DHT) decreased Sirtuin 6 expression and exacerbated cell apoptosis. Ectopic expression of Sirtuin 6 sufficiently inhibited DHT-induced cell apoptosis. Mechanically, we found AR inhibited Sirtuin 6, leading to the repression of binding of Sirtuin 6 with PGC-1α. This resulted in acetylation of PGC-1α and inhibition of its activity, further triggered the loss of mitochondrial homeostasis. Our results provided new insights to the underlying mechanisms of gender differences in AKI, suggesting Sirtuin 6 maybe a new therapeutic target for preventing AKI in male patients.

An efficient CRISPR-Cas12a promoter editing system for crop improvement

Promoter editing represents an innovative approach to introduce quantitative trait variation (QTV) in crops. However, an efficient promoter editing system for QTV needs to be established. Here we develop a CRISPR-Cas12a promoter editing (CAPE) system that combines a promoter key-region estimating model and an efficient CRISPR-Cas12a-based multiplexed or singular editing system. CAPE is benchmarked in rice to produce QTV continuums for grain starch content and size by targeting OsGBSS1 and OsGS3, respectively. We then apply CAPE for promoter editing of OsD18, a gene encoding GA3ox in the gibberellin biosynthesis pathway. The resulting lines carry a QTV continuum of semidwarfism without significantly compromising grain measures. Field trials demonstrated that the OsD18 promoter editing lines have the same yield performance and antilodging phenotype as the Green Revolution OsSD1 mutants in different genetic backgrounds. Hence, promoter editing of OsD18 generates a quantitative Green Revolution trait. Together, we demonstrate a CAPE-based promoter editing and tuning pipeline for efficient production of useful QTV continuum in crops.

A natural allele of proteasome maturation factor improves rice resistance to multiple pathogens

Crops with broad-spectrum resistance loci are highly desirable in agricultural production because these loci often confer resistance to most races of a pathogen or multiple pathogen species. Here we discover a natural allele of proteasome maturation factor in rice, UMP1^R2115, that confers broad-spectrum resistance to Magnaporthe oryzae, Rhizoctonia solani, Ustilaginoidea virens and Xanthomonas oryzae pv. oryzae. Mechanistically, this allele increases proteasome abundance and activity to promote the degradation of reactive oxygen species-scavenging enzymes including peroxidase and catalase upon pathogen infection, leading to elevation of H₂O₂ accumulation for defence. In contrast, inhibition of proteasome function or overexpression of peroxidase/catalase-encoding genes compromises UMP1^R2115-mediated resistance. More importantly, introduction of UMP1^R2115 into a disease-susceptible rice variety does not penalize grain yield while promoting disease resistance. Our work thus uncovers a broad-spectrum resistance pathway integrating de-repression of plant immunity and provides a valuable genetic resource for breeding high-yield rice with multi-disease resistance.

Identification of major quantitative trait loci and candidate genes for seed weight in soybean

Four major quantitative trait loci for 100-seed weight were identified in a soybean RIL population under five environments, and the most likely candidate genes underlying these loci were identified. Seed weight is an important target of soybean breeding. However, the genes underlying the major quantitative trait loci (QTL) controlling seed weight remain largely unknown. In this study, a soybean population of 300 recombinant inbred lines (RILs) derived from a cross between PI595843 (PI) and WH was used to map the QTL and identify candidate genes for seed weight. The RIL population was genotyped through whole genome resequencing, and phenotyped for 100-seed weight under five environments. A total of 38 QTL were detected, and four major QTL, each explained at least 10% of the variation in 100-seed weight, were identified. Six candidate genes within these four major QTL regions were identified by analyses of their tissue expression patterns, gene annotations, and differential gene expression levels in soybean seeds during four developmental stages between two parental lines. Further sequence variation analyses revealed a C to T substitution in the first exon of the Glyma.19G143300, resulting in an amino acid change between PI and WH, and thus leading to a different predicted kinase domain, which might affect its protein function. Glyma.19G143300 is highly expressed in soybean seeds and encodes a leucine-rich repeat receptor-like protein kinase (LRR-RLK). Its predicted protein has typical domains of LRR-RLK family, and phylogenetic analyses reveled its similarity with the known LRR-RLK protein XIAO (LOC_Os04g48760), which is involved in controlling seed size. The major QTL and candidate genes identified in this study provide useful information for molecular breeding of new soybean cultivars with desirable seed weight.

Deleting Gata4 in hepatocytes promoted the progression of NAFLD via increasing steatosis and apoptosis, and desensitizing insulin signaling

Gata4 is a member of the zinc finger GATA transcription factor family and is required for liver development during the embryonic stage. Gata4 expression is repressed during NAFLD progression, however how it functions in this situation remains unclear. Here, Gata4 was deleted specifically in hepatocytes via Cre recombinase driven by the Alb promoter region. Under a high-fat diet (HFD) or methionine and choline deficient diet (MCD), Gata4 knockout (KO) male, but not female, mice displayed more severe NAFLD or NASH, evidenced by increased steatosis, fibrosis, as well as a higher NAS score and serum ALT level. The Gata4KO male liver exposed to a HFD or MCD had a reduced ratio of pACC/ACC, similar to the Gata4KO hepatocytes treated with palmitic acid. More cell apoptosis, which is associated with activated JNK signaling and inhibited NFκB signaling, was observed in the Gata4KO male liver and isolated hepatocytes. However, the inflammatory status in the Gata4KO male liver was similar to the control liver. Importantly, lower activation of AKT signaling in the liver, which is consistent with de-sensitized insulin signaling in isolated hepatocytes, was found in the Gata4KO male. In summary, our data demonstrated that loss of Gata4 in hepatocytes promoted NAFLD progression in male mice.

SIRT6 in Aging, Metabolism, Inflammation and Cardiovascular Diseases

As an important NAD⁺-dependent enzyme, SIRT6 has received significant attention since its discovery. In view of observations that SIRT6-deficient animals exhibit genomic instability and metabolic disorders and undergo early death, SIRT6 has long been considered a protein of longevity. Recently, growing evidence has demonstrated that SIRT6 functions as a deacetylase, mono-ADP-ribosyltransferase and long fatty deacylase and participates in a variety of cellular signaling pathways from DNA damage repair in the early stage to disease progression. In this review, we elaborate on the specific substrates and molecular mechanisms of SIRT6 in various physiological and pathological processes in detail, emphasizing its links to aging (genomic damage, telomere integrity, DNA repair), metabolism (glycolysis, gluconeogenesis, insulin secretion and lipid synthesis, lipolysis, thermogenesis), inflammation and cardiovascular diseases (atherosclerosis, cardiac hypertrophy, heart failure, ischemia-reperfusion injury). In addition, the most recent advances regarding SIRT6 modulators (agonists and inhibitors) as potential therapeutic agents for SIRT6-mediated diseases are reviewed.

MicroRNAs in doxorubicin-induced cardiotoxicity: The DNA damage response

Doxorubicin (DOX) is a chemotherapeutic drug widely used for cancer treatment, but its use is limited by cardiotoxicity. Although free radicals from redox cycling and free cellular iron have been predominant as the suggested primary pathogenic mechanism, novel evidence has pointed to topoisomerase II inhibition and resultant genotoxic stress as the more fundamental mechanism. Recently, a growing list of microRNAs (miRNAs) has been implicated in DOX-induced cardiotoxicity (DIC). This review summarizes miRNAs reported in the recent literature in the context of DIC. A particular focus is given to miRNAs that regulate cellular responses downstream to DOX-induced DNA damage, especially p53 activation, pro-survival signaling pathway inhibition (e.g., AMPK, AKT, GATA-4, and sirtuin pathways), mitochondrial dysfunction, and ferroptosis. Since these pathways are potential targets for cardioprotection against DOX, an understanding of how miRNAs participate is necessary for developing future therapies.

SIRT6 Mitigates Heart Failure With Preserved Ejection Fraction in Diabetes

BACKGROUND

Heart failure with preserved ejection fraction (HFpEF) is a growing health problem without effective therapies. Epidemiological studies indicate that diabetes is a strong risk factor for HFpEF, and about 45% of patients with HFpEF are suffering from diabetes, yet the underlying mechanisms remain elusive.

METHODS

Using a combination of echocardiography, hemodynamics, RNA-sequencing, molecular biology, in vitro and in vivo approaches, we investigated the roles of SIRT6 (sirtuin 6) in regulation of endothelial fatty acid (FA) transport and HFpEF in diabetes.

RESULTS

We first observed that endothelial SIRT6 expression was markedly diminished in cardiac tissues from heart failure patients with diabetes. We then established an experimental mouse model of HFpEF in diabetes induced by a combination of the long-term high-fat diet feeding and a low-dose streptozocin challenge. We also generated a unique humanized SIRT6 transgenic mouse model, in which a single copy of human SIRT6 transgene was engineered at mouse Rosa26 locus and conditionally induced with the Cre-loxP technology. We found that genetically restoring endothelial SIRT6 expression in the diabetic mice ameliorated diastolic dysfunction concurrently with decreased cardiac lipid accumulation. SIRT6 gain- or loss-of-function studies showed that SIRT6 downregulated endothelial FA uptake. Mechanistically, SIRT6 suppressed endothelial expression of PPARγ through SIRT6-dependent deacetylation of histone H3 lysine 9 around PPARγ promoter region; and PPARγ reduction mediated SIRT6-dependent inhibition of endothelial FA uptake. Importantly, oral administration of small molecule SIRT6 activator MDL-800 to diabetic mice mitigated cardiac lipid accumulation and diastolic dysfunction.

CONCLUSIONS

The impairment of endothelial SIRT6 expression links diabetes to HFpEF through the alteration of FA transport across the endothelial barrier. Genetic and pharmacological strategies that restored endothelial SIRT6 function in mice with diabetes alleviated experimental HFpEF by limiting FA uptake and improving cardiac metabolism, thus warranting further clinical evaluation.

Sirt6 deficiency contributes to mitochondrial fission and oxidative damage in podocytes via ROCK1-Drp1 signalling pathway

OBJECTIVES

Increasing evidence suggests that mitochondrial dysfunction is the key driver of angiotensin II (Ang II)-induced kidney injury. This study was designed to investigate whether Sirtuin 6 (Sirt6) could affect Ang II-induced mitochondrial damage and the potential mechanisms.

MATERIALS AND METHODS

Podocyte-specific Sirt6 knockout mice were infused with Ang II and cultured podocytes were stimulated with Ang II to evaluate the effects of Sirt6 on mitochondrial structure and function in podocytes. Immunofluorescence staining was used to detect protein expression and mitochondrial morphology in vitro. Electron microscopy was used to assess mitochondrial morphology in mice. Western blotting was used to quantify protein expression.

RESULTS

Mitochondrial fission and decreased Sirt6 expression were observed in podocytes from Ang II-infused mice. In Sirt6-deficient mice, Ang II infusion induced increased apoptosis and mitochondrial fragmentation in podocytes than that in Ang II-infused wild-type mice. In cultured human podocytes, Sirt6 knockdown exacerbated Ang II-induced mitochondrial fission, whereas Sirt6 overexpression ameliorated the Ang II-induced changes in the balance between mitochondrial fusion and fission. Functional studies revealed that Sirt6 deficiency exacerbated mitochondrial fission by promoting dynamin-related protein 1 (Drp1) phosphorylation. Furthermore, Sirt6 mediated Drp1 phosphorylation by promoting Rho-associated coiled coil-containing protein kinase 1 (ROCK1) expression.

CONCLUSION

Our study has identified Sirt6 as a vital factor that protects against Ang II-induced mitochondrial fission and apoptosis in podocytes via the ROCK1-Drp1 signalling pathway.

Sirtuin 6 inhibition protects against glucocorticoid-induced skeletal muscle atrophy by regulating IGF/PI3K/AKT signaling

Chronic activation of stress hormones such as glucocorticoids leads to skeletal muscle wasting in mammals. However, the molecular events that mediate glucocorticoid-induced muscle wasting are not well understood. Here, we show that SIRT6, a chromatin-associated deacetylase indirectly regulates glucocorticoid-induced muscle wasting by modulating IGF/PI3K/AKT signaling. Our results show that SIRT6 levels are increased during glucocorticoid-induced reduction of myotube size and during skeletal muscle atrophy in mice. Notably, overexpression of SIRT6 spontaneously decreases the size of primary myotubes in a cell-autonomous manner. On the other hand, SIRT6 depletion increases the diameter of myotubes and protects them against glucocorticoid-induced reduction in myotube size, which is associated with enhanced protein synthesis and repression of atrogenes. In line with this, we find that muscle-specific SIRT6 deficient mice are resistant to glucocorticoid-induced muscle wasting. Mechanistically, we find that SIRT6 deficiency hyperactivates IGF/PI3K/AKT signaling through c-Jun transcription factor-mediated increase in IGF2 expression. The increased activation, in turn, leads to nuclear exclusion and transcriptional repression of the FoxO transcription factor, a key activator of muscle atrophy. Further, we find that pharmacological inhibition of SIRT6 protects against glucocorticoid-induced muscle wasting in mice by regulating IGF/PI3K/AKT signaling implicating the role of SIRT6 in glucocorticoid-induced muscle atrophy.

The histone deacetylase SIRT6 promotes glycolysis through the HIF-1α/HK2 signaling axis and induces erlotinib resistance in non-small cell lung cancer

Erlotinib is a first-generation epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI). Overcoming erlotinib resistance is crucial to improve the survival of advanced non-small cell lung cancer (NSCLC) patients with sensitive EGFR mutations. It is also an important clinical problem that urgently needs a solution. In this study, we explored strategies to overcome erlotinib resistance from the perspective of energy metabolism. SIRT6 is a histone deacetylase. Here, we found that high expression of SIRT6 is associated with poor prognosis of lung adenocarcinoma, especially in EGFR-mutated NSCLC patients. The next cell experiment found that SIRT6 expression increased in erlotinib-resistant cells, and SIRT6 expression was negatively correlated with the sensitivity of NSCLC to erlotinib. Inhibition of SIRT6 promoted erlotinib-induced apoptosis in erlotinib-resistant cells, and glycolysis in drug-resistant cells was also inhibited. Functional studies have shown that SIRT6 increases glycolysis through the HIF-1α/HK2 signaling axis in drug-resistant cells and inhibits the sensitivity of NSCLC cells to erlotinib. In addition, the HIF-1α blocker PX478-2HCL attenuated the glycolysis and erlotinib resistance induced by SIRT6. More importantly, we confirmed the antitumor effect of SIRT6 inhibition combined with erlotinib in NSCLC-bearing mice. Our findings indicate that the cancer metabolic pathway regulated by SIRT6 may be a new target for attenuating NSCLC erlotinib resistance and has potential as a biomarker or therapeutic target to improve outcomes in NSCLC patients.

Damage of uremic myocardium by p-cresyl sulfate and the ameliorative effect of Klotho by regulating SIRT6 ubiquitination

Uremic cardiomyopathy (UCM) is a common complication in patients with chronic kidney disease (CKD) and an important risk factor for death. P-Cresyl sulfate (PCS) is a damaging factor in UCM, and Klotho is a protective factor. However, the molecular mechanisms of Klotho and PCS in UCM and the relationship between PCS and Klotho are unclear. In vitro, Klotho treatment inhibited PCS-induced cardiomyocyte hypertrophy and apoptosis by blocking mTOR phosphorylation and inhibiting DNA double-strand breaks (DSBs), respectively. Moreover, PCS increased SIRT6 protein ubiquitination and downregulated SIRT6 protein expression, while Klotho inhibited SIRT6 protein ubiquitination and upregulated SIRT6 protein expression. In a mouse model of 5/6 nephrectomy (5/6Nx)-induced UCM, the expression of Klotho in the kidney and serum was decreased, and the expression of SIRT6 protein in myocardial tissues was lower. PCS further reduced Klotho and SIRT6 expression, aggravated heart structure and function abnormalities, and increased myocardial cell apoptosis in UCM mice. Administration of Klotho protein inhibited the downregulation of SIRT6 protein expression and improved cardiac structure and function. Furthermore, serum PCS level was associated with the left ventricular mass (LVM) and left ventricular mass index (LVMI) in hemodialysis patients. In conclusion, the uremic toxin PCS injures cardiomyocytes via mTOR phosphorylation and DSBs, and Klotho antagonizes the damaging effects of PCS. Moreover, the SIRT6 protein plays an important role in UCM, and Klotho suppresses SIRT6 ubiquitination induced by PCS, further improves cardiac structure and function in UCM and exerts protective effects.

SIRT6 in Vascular Diseases, from Bench to Bedside

Aging is a key risk factor for angiogenic dysfunction and cardiovascular diseases, including heart failure, hypertension, atherosclerosis, diabetes, and stroke. Members of the NAD+-dependent class III histone deacetylase family, sirtuins, are conserved regulators of aging and cardiovascular and cerebrovascular diseases. The sirtuin SIRT6 is predominantly located in the nucleus and shows deacetylase activity for acetylated histone 3 lysine 56 and lysine 9 as well as for some non-histone proteins. Over the past decade, experimental analyses in rodents and non-human primates have demonstrated the critical role of SIRT6 in extending lifespan. Recent studies highlighted the pleiotropic protective actions of SIRT6 in angiogenesis and cardiovascular diseases, including atherosclerosis, hypertension, heart failure, and stroke. Mechanistically, SIRT6 participates in vascular diseases via epigenetic regulation of endothelial cells, vascular smooth muscle cells, and immune cells. Importantly, SIRT6 activators (e.g., MDL-800/MDL-811) have provided therapeutic value for treating age-related vascular disorders. Here, we summarized the roles of sirtuins in cardiovascular diseases; reviewed recent advances in the understanding of SIRT6 in vascular biology, cardiovascular aging, and diseases; highlighted its therapeutic potential; and discussed future perspectives.

Erythrocyte Membrane-Coated Invisible Acoustic-Sensitive Nanoparticle for Inducing Tumor Thrombotic Infarction by Precisely Damaging Tumor Vascular Endothelium

Selective induction of tumor thrombus infarction is a promising antitumor strategy. Non-persistent embolism due to non-compacted thrombus and activated fibrinolytic system within the tumor large blood vessels and tumor margin recurrence are the main therapeutic bottlenecks. Herein, an erythrocyte membrane-coated invisible acoustic-sensitive nanoparticle (TXA+DOX/PFH/RBCM@cRGD) is described, which can induce tumor thrombus infarction by precisely damaging tumor vascular endothelium. It is revealed that TXA+DOX/PFH/RBCM@cRGD can effectively accumulate on the endothelial surface of tumor vessels with the help of the red blood cell membrane (RBCM) stealth coating and RGD cyclic peptide (cRGD), which can be delivered in a targeted manner as nanoparticle missiles. As a kind of phase-change material, perfluorohexane (PFH) nanodroplets possess excellent acoustic responsiveness. Acoustic-sensitive missiles can undergo an acoustic phase transition and intense cavitation with response to low-intensity focused ultrasound (LIFU), damaging the tumor vascular endothelium, rapidly initiating the coagulation cascade, and forming thromboembolism in the tumor vessels. The drugs loaded in the inner water phase are released explosively. Tranexamic acid (TXA) inhibits the fibrinolytic system, and doxorubicin (DOX) eliminates the margin survival. In summary, a stealthy and acoustically responsive multifunctional nanoparticle delivery platform is successfully developed for inducing thrombus infarction by precisely damaging tumor vascular endothelium.

Deacetylation of Caveolin-1 by Sirt6 induces autophagy and retards high glucose-stimulated LDL transcytosis and atherosclerosis formation

BACKGROUND

Atherosclerosis (AS) is the basis of diabetic macrovascular complications. The plasma low-density lipoprotein (LDL) particles transcytosis across endothelial cells (ECs) and deposition under the endothelium is the initiation step of AS. We previously reported that high glucose inhibits the autophagic degradation of Caveolin-1 and promote LDL transcytosis across ECs, which in turn accelerates atherosclerotic progression. Since Sirt6 is a chromatin-associated protein with deacetylation activity, whether it can regulate Caveolin-1 acetylation and regulating the autophagic degradation of Caveolin-1 remains elusive.

METHODS

Autophagy and histone acetylation were assessed in the umbilical cords of patients with gestational diabetes mellitus (GDM) by immunohistochemistry. An in vitro model of LDL transcytosis was established, and the role of Sirt6 in LDL transcytosis across endothelial cells was clarified. The effect of Sirt6 on the autophagic degradation of Caveolin-1 under hyperglycemic conditions was explored in a streptozotocin (STZ)-induced diabetic AS model established using the ApoE^-/- mice.

RESULTS

Caveolin-1 and acetylated histone H3 levels were significantly increased, while LC3B and Sirt6 were downregulated in the monolayer of the vascular wall from GDM and type 2 diabetes mellitus (T2DM) patients. Immunoprecipitation assays showed that Sirt6 interacts with Caveolin-1 and specifically mediated its acetylation levels. Immuno-electron microscopy (EM) further indicated that Sirt6 overexpression triggered the autophagic lysosomal degradation of Caveolin-1. ECs-specific overexpression of Sirt6 by adeno-associated viral vector serotype 9 (AAV9) induced autophagy, reduced Caveolin-1 expression, and ameliorated atherosclerotic plaque formation in STZ-induced diabetic ApoE^-/- mice.

CONCLUSION

Sirt6-mediated acetylation of Caveolin-1 activates its autophagic degradation and inhibits high glucose-stimulated LDL transcytosis. Thus, the Sirt6/Caveolin-1 autophagic pathway plays a crucial role in diabetic AS, and the overexpression or activation of Sirt6 is a novel therapeutic strategy.

SIRT6 Protects Against Myocardial Ischemia-Reperfusion Injury by Attenuating Aging-Related CHMP2B Accumulation

Impaired autophagic flux induces aging-related ischemia vulnerability, which is the hallmark pathology in cardiac aging. Our previous work has confirmed that the accumulation of charged multivesicular body protein 2B (CHMP2B), a subunit of the ESCRT-III complex, in the heart can impair autophagy flux. However, whether CHMP2B accumulation contributes to aging-related intolerance to ischemia/reperfusion (I/R) injury and the regulatory mechanism for CHMP2B in aged heart remain elusive. The cardiac CHMP2B level was significantly higher in aged human myocardium than that in young myocardium. Increased CHMP2B were shown to inhibit autophagic flux leading to the deterioration of MI/R injury in aged mice hearts. Interestingly, a negative correlation was observed between SIRT6 and CHMP2B expression in human heart samples. Specific activation of SIRT6 suppressed CHMP2B accumulation and ameliorated autophagy flux in aged hearts. Using myocardial-specific SIRT6 heterozygous knockout mice and recovery experiments confirmed that SIRT6 regulated myocardial CHMP2B levels. Finally, activation of SIRT6 decreased acetylation of FoxO1 to promote its transcriptional function on Atrogin-1, a muscle-specific ubiquitin ligase, which subsequently enhanced the degradation of CHMP2B by Atrogin-1. This is a novel mechanism for SIRT6 against aging-related myocardial ischemia vulnerability, particularly by preventing excessive accumulation of autophagy key factors.

Sirt6 regulates autophagy in AGE-treated endothelial cells via KLF4

BACKGROUND AND AIMS

High glucose and its byproducts are important factors causing dysfunction of endothelial cells. Autophagy is critical for endothelial cellular homeostasis. However, the specific molecular mechanism of how autophagy is regulated in endothelial cells under high-glucose condition remains unknown. We aim to explore the role Sirt6 plays in regulating autophagy in AGE-treated endothelial cells and how this function is exerted via KLF4.

METHODS AND RESULTS

Our results indicate that autophagy level increased in AGE-treated endothelial cells alongside with higher Sirt6 and KLF4 expression level. What's more, knock-in of Sirt6 by adenovirus led to augmented autophagy level while knockdown of Sirt6 led to the opposite. We also verified that Sirt6 affected KLF4 expression positively but KLF4 didn't influence Sirt6 expression level while knocking out of KLF4 impaired Sirt6-enhanced autophagy. Finally we found that STZ-induced diabetic mice showed more autophagosomes in endothelium and Sirt6 knockdown by adeno-associated virus reduced the number of autophagosomes. Knockdown of Sirt6 also caused impaired endothelium integrity but echocardiography indicated there were no significant functional differences.

CONCLUSION

Our research reveals more about how Sirt6 regulates autophagy in endothelial cells under high-glucose simulated condition and provides further insight into the relationships between Sirt6 and KLF4.

Roles of Wnt Signaling Pathway and ROR2 Receptor in Embryonic Development: An Update Review Article

The Wnt family is a large class of highly conserved cysteine-rich secretory glycoproteins that play a vital role in various cellular and physiological courses through different signaling pathways during embryogenesis and tissue homeostasis 3. Wnt5a is a secreted glycoprotein that belongs to the noncanonical Wnt family and is involved in a wide range of developmental and tissue homeostasis. A growing body of evidence suggests that Wnt5a affects embryonic development, signaling through various receptors, starting with the activation of β-catenin by Wnt5a. In addition to affecting planar cell polarity and Ca2+ pathways, β-catenin also includes multiple signaling cascades that regulate various cell functions. Secondly, Wnt5a can bind to Ror receptors to mediate noncanonical Wnt signaling and a significant ligand for Ror2 in vertebrates. Consistent with the multiple functions of Wnt5A/Ror2 signaling, Wnt5A knockout mice exhibited various phenotypic defects, including an inability to extend the anterior and posterior axes of the embryo. Numerous essential roles of Wnt5a/Ror2 in development have been demonstrated. Therefore, Ror signaling pathway become a necessary target for diagnosing and treating human diseases. The Wnt5a- Ror2 signaling pathway as a critical factor has attracted extensive attention.

Sirt6 protects cardiomyocytes against doxorubicin-induced cardiotoxicity by inhibiting P53/Fas-dependent cell death and augmenting endogenous antioxidant defense mechanisms

Sirt6, a class III NAD⁺-dependent deacetylase of the sirtuin family, is a highly specific H3 deacetylase and plays important roles in regulating cellular growth and death. The induction of oxidative stress and death is the critical mechanism involved in cardiomyocyte injury and cardiac dysfunction in doxorubicin-induced cardiotoxicity, but the regulatory role of Sirt6 in the fate of DOX-impaired cardiomyocytes is poorly understood. In the present study, we exposed Sirt6 heterozygous (Sirt6^+/-) mice and their littermates as well as cultured neonatal rat cardiomyocytes to DOX, then investigated the role of Sirt6 in mitigating oxidative stress and cardiac injury in the DOX-treated myocardium. Sirt6 partial knockout or silencing worsened cardiac damage, remodeling, and oxidative stress injury in mice or cultured cardiomyocytes with DOX challenge. Cardiomyocytes infected with adenoviral constructs encoding Sirt6 showed reversal of this DOX-induced damage. Intriguingly, Sirt6 reduced oxidative stress injury by upregulating endogenous antioxidant levels, interacted with oxidative stress-stirred p53, and acted as a co-repressor of p53 in nuclei. Sirt6 was recruited by p53 to the promoter regions of the target genes Fas and FasL and further suppressed p53 transcription activity by reducing histone acetylation. Sirt6 inhibited Fas/FasL signaling and attenuated both Fas-FADD-caspase-8 apoptotic and Fas-RIP3 necrotic pathways. These results indicate that Sirt6 protects the heart against DOX-induced cardiotoxicity by upregulating endogenous antioxidants, as well as suppressing oxidative stress and cell death signaling pathways dependent on ROS-stirred p53 transcriptional activation, thus reducing Fas-FasL-mediated apoptosis and necrosis. •Sirt6 is significantly decreased in DOX-insulted mouse hearts and cardiomyocytes. •Sirt6 attenuates DOX-induced cardiac atrophy, dysfunction and oxidative stress. • Sirt6 reduces oxidative stress injury by upregulating endogenous antioxidants. • Sirt6 interacts with p53 as a co-repressor to suppress p53 transcriptional regulation and inhibits Fas-FasL-mediated apoptosis and necrosis downstream of p53.

Overexpression of OsLCT2, a Low-Affinity Cation Transporter Gene, Reduces Cadmium Accumulation in Shoots and Grains of Rice

Cadmium (Cd)-contaminated rice is a serious issue affecting food safety. Understanding the molecular regulatory mechanisms of Cd accumulation in rice grains is crucial to minimizing Cd concentrations in grains. We identified a member of the low-affinity cation transporter family, OsLCT2 in rice. It was a membrane protein. OsLCT2 was expressed in all tissues of the elongation and maturation zones in roots, with the strongest expression in pericycle and stele cells adjacent to the xylem. When grown in Cd-contaminated paddy soils, rice plants overexpressing OsLCT2 significantly reduced Cd concentrations in the straw and grains. Hydroponic experiment demonstrated its overexpression decreased the rate of Cd translocation from roots to shoots, and reduced Cd concentrations in xylem sap and in shoots of rice. Moreover, its overexpression increased Zn concentrations in roots by up-regulating the expression of OsZIP9, a gene responsible for Zn uptake. Overexpression of OsLCT2 reduces Cd accumulation in rice shoots and grains by limiting the amounts of Cd loaded into the xylem and restricting Cd translocation from roots to shoots of rice. Thus, OsLCT2 is a promising genetic resource to be engineered to reduce Cd accumulation in rice grains.

Emerging roles of Sirtuin 2 in cardiovascular diseases

Sirtuins are a family of NAD⁺ -dependent deacetylases implicated in a wide variety of age-associated pathologies, including cardiovascular disorders. Among the seven mammalian sirtuins, SIRT2 modulates various cellular processes through the deacetylation or deacylation of their target proteins. Notably, the levels of SIRT2 in the heart decline with age and other pathological conditions, leading to cardiovascular dysfunction. In the present review, we discuss the emerging roles of SIRT2 in cardiovascular dysfunction and heart failure associated with factors like age, hypertension, oxidative stress, and diabetes. We also discuss the potential of using inhibitors to study the unexplored role of SIRT2 in the heart. While SIRT2 undoubtedly plays a crucial role in the cardiovascular system, its functions are only beginning to be understood, making it an attractive candidate for further research in the field.

Sirtuin 6 promotes eosinophil differentiation by activating GATA-1 transcription factor

There is evidence emerging that exposure to cold temperatures enhances alternative activation of macrophages in white adipose tissue (WAT), which promotes adipocyte beiging and adaptive thermogenesis. Although we recently reported that NAD⁺‐dependent deacetylase sirtuin 6 (Sirt6) drives alternatively activated (M2) macrophage polarization, the role of myeloid Sirt6 in adaptive thermogenesis had remained elusive. In this study, we demonstrate that myeloid Sirt6 deficiency impaired both thermogenic responses and M2 macrophage infiltration in subcutaneous WAT (scWAT) during cold exposure. Moreover, the infiltration of Siglec‐F‐positive eosinophils in scWAT and Th2 cytokines levels was reduced in myeloid Sirt6 knockout mice. An ex vivo bone marrow‐derived cell culture experiment indicated that Sirt6 was required for eosinophil differentiation independent of its deacetylase activity. Data from our in vitro experiments show that Sirt6 acted as a transcriptional cofactor of GATA‐1, independent of its catalytic function as a deacetylase or ADP‐ribosyltransferase. Specifically, Sirt6 physically interacted with GATA‐1, and enhanced GATA‐1’s acetylation and transcriptional activity by facilitating its cooperation with p300. Overall, our results suggest that myeloid Sirt6 plays an important role in eosinophil differentiation and fat beiging/adaptive thermogenesis, which is at least in part due to its ability to bind GATA‐1 and stimulate its transcriptional activity.

Establishment of a Mass-Spectrometry-Based Method for the Identification of the In Vivo Whole Blood and Plasma ADP-Ribosylomes

Blood and plasma proteins are heavily investigated as biomarkers for different diseases. However, the post-translational modification states of these proteins are rarely analyzed since blood contains many enzymes that rapidly remove these modifications after sampling. In contrast to the well-described role of protein ADP-ribosylation in cells and organs, its role in blood remains mostly uncharacterized. Here, we discovered that plasma phosphodiesterases and/or ADP-ribosylhydrolases rapidly demodify in vitro ADP-ribosylated proteins. Thus, to identify the in vivo whole blood and plasma ADP-ribosylomes, we established a mass-spectrometry-based workflow that was applied to blood samples collected from LPS-treated pigs (Sus scrofa domesticus), which serves as a model for human systemic inflammatory response syndrome. These analyses identified 60 ADP-ribosylated proteins, 17 of which were ADP-ribosylated plasma proteins. This new protocol provides an important step forward for the rapidly developing field of ADP-ribosylation and defines the blood and plasma ADP-ribosylomes under both healthy and disease conditions.

Sirtuins: To Be or Not To Be in Diabetic Cardiomyopathy

Diabetic cardiomyopathy is the leading cause of death among people with diabetes. Despite its severity and poor prognosis, there are currently no approved specific drugs to prevent or even treat diabetic cardiomyopathy. There is a need to understand the pathogenic mechanisms underlying the development of diabetic cardiomyopathy to design new therapeutic strategies. These mechanisms are complex and intricate and include metabolic dysregulation, inflammation, oxidative stress, fibrosis, and apoptosis. Sirtuins, a group of deacetylase enzymes, play an important role in all these processes and are, therefore, potential molecular targets for treating this disease. In this review, we discuss the role of sirtuins in the heart, focusing on their contribution to the pathogenesis of diabetic cardiomyopathy and how their modulation could be therapeutically useful.

Regulated cell death pathways in doxorubicin-induced cardiotoxicity

Doxorubicin is a chemotherapeutic drug used for the treatment of various malignancies; however, patients can experience cardiotoxic effects and this has limited the use of this potent drug. The mechanisms by which doxorubicin kills cardiomyocytes has been elusive and despite extensive research the exact mechanisms remain unknown. This review focuses on recent advances in our understanding of doxorubicin induced regulated cardiomyocyte death pathways including autophagy, ferroptosis, necroptosis, pyroptosis and apoptosis. Understanding the mechanisms by which doxorubicin leads to cardiomyocyte death may help identify novel therapeutic agents and lead to more targeted approaches to cardiotoxicity testing.

SIRT6 in Senescence and Aging-Related Cardiovascular Diseases

SIRT6 belongs to the nicotinamide adenine dinucleotide (NAD⁺)-dependent deacetylases and has established diverse roles in aging, metabolism and disease. Its function is similar to the Silent Information Regulator 2 (SIR2), which prolongs lifespan and regulates genomic stability, telomere integrity, transcription, and DNA repair. It has been demonstrated that increasing the sirtuin level through genetic manipulation extends the lifespan of yeast, nematodes and flies. Deficiency of SIRT6 induces chronic inflammation, autophagy disorder and telomere instability. Also, these cellular processes can lead to the occurrence and progression of cardiovascular diseases (CVDs), such as atherosclerosis, hypertrophic cardiomyopathy and heart failure. Herein, we discuss the implications of SIRT6 regulates multiple cellular processes in cell senescence and aging-related CVDs, and we summarize clinical application of SIRT6 agonists and possible therapeutic interventions in aging-related CVDs.

Emerging roles of SIRT6 in human diseases and its modulators

The biological functions of sirtuin 6 (SIRT6; e.g., deacetylation, defatty-acylation, and mono-ADP-ribosylation) play a pivotal role in regulating lifespan and several fundamental processes controlling aging such as DNA repair, gene expression, and telomeric maintenance. Over the past decades, the aberration of SIRT6 has been extensively observed in diverse life-threatening human diseases. In this comprehensive review, we summarize the critical roles of SIRT6 in the onset and progression of human diseases including cancer, inflammation, diabetes, steatohepatitis, arthritis, cardiovascular diseases, neurodegenerative diseases, viral infections, renal and corneal injuries, as well as the elucidation of the related signaling pathways. Moreover, we discuss the advances in the development of small molecule SIRT6 modulators including activators and inhibitors as well as their pharmacological profiles toward potential therapeutics for SIRT6-mediated diseases.

Two Targets, One Hit: new Anticancer Therapeutics to Prevent Tumorigenesis Without Cardiotoxicity

A serious adverse effect of cancer therapies is cardiovascular toxicity, which significantly limits the widespread use of antineoplastic agents. The promising new field of cardio-oncology offers the identification of potent anti-cancer therapeutics that effectively inhibit cancer cell proliferation without causing cardiotoxicity. Future introduction of recently identified cardio-safe compounds into clinical practice (including ERK dimerization inhibitors or BAX allosteric inhibitors) is expected to help oncologists avoid unwanted cardiological complications associated with therapeutic interventions.

Resequencing of 1,143 indica rice accessions reveals important genetic variations and different heterosis patterns

Obtaining genetic variation information from indica rice hybrid parents and identification of loci associated with heterosis are important for hybrid rice breeding. Here, we resequence 1,143 indica accessions mostly selected from the parents of superior hybrid rice cultivars of China, identify genetic variations, and perform kinship analysis. We find different hybrid rice crossing patterns between 3- and 2-line superior hybrid lines. By calculating frequencies of parental variation differences (FPVDs), a more direct approach for studying rice heterosis, we identify loci that are linked to heterosis, which include 98 in superior 3-line hybrids and 36 in superior 2-line hybrids. As a proof of concept, we find two accessions harboring a deletion in OsNramp5, a previously reported gene functioning in cadmium absorption, which can be used to mitigate rice grain cadmium levels through hybrid breeding. Resource of indica rice genetic variation reported in this study will be valuable to geneticists and breeders.

Hybrid rice cultivars are widely planted around the world. Here, the authors resequence 1,143 indica accessions, focusing on the parents of superior hybrid rice lines in China, and reveal genetic loci that are associated with heterosis via measuring frequency of parental variation difference (FPVD).