Sirtuin Modulators in Cellular and Animal Models of Human Diseases

Sirtuins as Players in the Signal Transduction of Citrus Flavonoids

Sirtuins (SIRTs) belong to the family of nicotine adenine dinucleotide (NAD+)-dependent class III histone deacetylases, which come into play in the regulation of epigenetic processes through the deacetylation of histones and other substrates. The human genome encodes for seven homologs (SIRT1-7), which are localized into the nucleus, cytoplasm, and mitochondria, with different enzymatic activities and regulatory mechanisms. Indeed, SIRTs are involved in different physio-pathological processes responsible for the onset of several human illnesses, such as cardiovascular and neurodegenerative diseases, obesity and diabetes, age-related disorders, and cancer. Nowadays, it is well-known that Citrus fruits, typical of the Mediterranean diet, are an important source of bioactive compounds, such as polyphenols. Among these, flavonoids are recognized as potential agents endowed with a wide range of beneficial properties, including antioxidant, anti-inflammatory, hypolipidemic, and antitumoral ones. On these bases, we offer a comprehensive overview on biological effects exerted by Citrus flavonoids via targeting SIRTs, which acted as modulator of several signaling pathways. According to the reported studies, Citrus flavonoids appear to be promising SIRT modulators in many different pathologies, a role which might be potentially evaluated in future therapies, along with encouraging the study of those SIRT members which still lack proper evidence on their support.

Pyruvate kinase is post-translationally regulated by sirtuin 2 in Aedes aegypti mosquitoes

We previously demonstrated that Aedes aegypti pyruvate kinase (AaPK) plays a key role in the regulation of both carbon and nitrogen metabolism in mosquitoes. To further elucidate whether AaPK can be post-translationally regulated by Ae. aegypti sirtuin 2 (AaSirt2), an NAD+-dependent deacetylase that catalyzes the removal of acetyl groups from acetylated lysine residues, we conducted a series of analysis in non-starved and starved female mosquitoes. Transcriptional and protein profiles of AaSirt2, analyzed by qPCR and western blots, indicated that the AaSirt2 is differentially modulated in response to sugar or blood feeding in mosquito tissues dissected at different times during the first gonotrophic cycle. We also found that AaSirt2 is localized in both cytosolic and mitochondrial cellular compartments of fat body and thorax. Multiple lysine-acetylated proteins were detected by western blotting in both cellular compartments. Furthermore, western blotting of immunoprecipitated proteins provided evidence that AaPK is lysine-acetylated and bound with AaSirt2 in the cytosolic fractions of fat body and thorax from non-starved and starved females. In correlation with these results, we also discovered that RNAi-mediated knockdown of AaSirt2 in the fat body of starved females significantly decreased AaPK protein abundance. Notably, survivorship of AaSirt2-deficient females maintained under four different nutritional regimens was not significantly affected. Taken together, our data reveal that AaPK is post-translationally regulated by AaSirt2.

Sirtuins as Potential Targets for Neuroprotection: Mechanisms of Early Brain Injury Induced by Subarachnoid Hemorrhage

Subarachnoid hemorrhage (SAH) is a prevalent cerebrovascular disease with significant global mortality and morbidity rates. Despite advancements in pharmacological and surgical approaches, the quality of life for SAH survivors has not shown substantial improvement. Traditionally, vasospasm has been considered a primary contributor to death and disability following SAH, but anti-vasospastic therapies have not demonstrated significant benefits for SAH patients' prognosis. Emerging studies suggest that early brain injury (EBI) may play a crucial role in influencing SAH prognosis. Sirtuins (SIRTs), a group of NAD + -dependent deacylases comprising seven mammalian family members (SIRT1 to SIRT7), have been found to be involved in neural tissue development, plasticity, and aging. They also exhibit vital functions in various central nervous system (CNS) processes, including cognition, pain perception, mood, behavior, sleep, and circadian rhythms. Extensive research has uncovered the multifaceted roles of SIRTs in CNS disorders, offering insights into potential markers for pathological processes and promising therapeutic targets (such as SIRT1 activators and SIRT2 inhibitors). In this article, we provide an overview of recent research progress on the application of SIRTs in subarachnoid hemorrhage and explore their underlying mechanisms of action.

Novel Thiazole-Based SIRT2 Inhibitors Discovered via Molecular Modelling Studies and Enzymatic Assays

Recently, the development of sirtuin small molecule inhibitors (SIRTIs) has been gaining attention for the treatment of different cancer types, but also to contrast neurodegenerative disease, diabetes, and autoimmune syndromes. In the search for SIRT2 modulators, the availability of several X-crystallographic data regarding SIRT2-ligand complexes has allowed for setting up a structure-based study, which is herein presented. A set of 116 SIRT2 inhibitors featuring different chemical structures has been collected from the literature and used for molecular docking studies involving 4RMG and 5MAT PDB codes. The information found highlights key contacts with the SIRT2 binding pocket such as Van der Waals and π-π stacking with Tyr104, Phe119, Phe234, and Phe235 in order to achieve high inhibitory ability values. Following the preliminary virtual screening studies, a small in-house library of compounds (1a-7a), previously investigated as putative HSP70 inhibitors, was described to guide the search for dual-acting HSP70/SIRT2 inhibitors. Biological and enzymatic assays validated the whole procedure. Compounds 2a and 7a were found to be the most promising derivatives herein proposed.

Oxidative stress in intervertebral disc degeneration: Molecular mechanisms, pathogenesis and treatment

Low back pain (LBP) is a leading cause of labour loss and disability worldwide, and it also imposes a severe economic burden on patients and society. Among symptomatic LBP, approximately 40% is caused by intervertebral disc degeneration (IDD). IDD is the pathological basis of many spinal degenerative diseases such as disc herniation and spinal stenosis. Currently, the therapeutic approaches for IDD mainly include conservative treatment and surgical treatment, neither of which can solve the problem from the root by terminating the degenerative process of the intervertebral disc (IVD). Therefore, further exploring the pathogenic mechanisms of IDD and adopting targeted therapeutic strategies is one of the current research hotspots. Among the complex pathophysiological processes and pathogenic mechanisms of IDD, oxidative stress is considered as the main pathogenic factor. The delicate balance between reactive oxygen species (ROS) and antioxidants is essential for maintaining the normal function and survival of IVD cells. Excessive ROS levels can cause damage to macromolecules such as nucleic acids, lipids, and proteins of cells, affect normal cellular activities and functions, and ultimately lead to cell senescence or death. This review discusses the potential role of oxidative stress in IDD to further understand the pathophysiological processes and pathogenic mechanisms of IDD and provides potential therapeutic strategies for the treatment of IDD.

SIRT2 inhibition by AGK2 enhances mycobacteria-specific stem cell memory responses by modulating beta-catenin and glycolysis

Bacille Calmette-Guerin (BCG) generates limited long-lasting adaptive memory responses leading to short-lived protection against adult pulmonary tuberculosis (TB). Here, we show that host sirtuin 2 (SIRT2) inhibition by AGK2 significantly enhances the BCG vaccine efficacy during primary infection and TB recurrence through enhanced stem cell memory (T_SCM) responses. SIRT2 inhibition modulated the proteome landscape of CD4⁺ T cells affecting pathways involved in cellular metabolism and T-cell differentiation. Precisely, AGK2 treatment enriched the IFNγ-producing T_SCM cells by activating β-catenin and glycolysis. Furthermore, SIRT2 specifically targeted histone H3 and NF-κB p65 to induce proinflammatory responses. Finally, inhibition of the Wnt/β-catenin pathway abolished the protective effects of AGK2 treatment during BCG vaccination. Taken together, this study provides a direct link between BCG vaccination, epigenetics, and memory immune responses. We identify SIRT2 as a key regulator of memory T cells during BCG vaccination and project SIRT2 inhibitors as potential immunoprophylaxis against TB.

Role of sirtuins in hepatocellular carcinoma progression and multidrug resistance: Mechanistical and pharmacological perspectives

Hepatocellular carcinoma (HCC) is the third most common cause of death from cancer worldwide. Therapeutic strategies are still challenging due to the high relapse rate after surgery and multidrug resistance (MDR). It is essential to better understand the mechanisms for HCC progression and MDR for the development of new therapeutic strategies. Mammalian sirtuins (SIRTs), a family of seven members, are related to tumor progression, MDR and prognosis and were proposed as potential prognostic markers, as well as therapeutic targets for treating cancer. SIRT1 is the most studied member and is overexpressed in HCC, playing an oncogenic role and predicting poor prognosis. Several manuscripts describe the role of SIRTs2-7 in HCC; most of them report an oncogenic role for SIRT2 and -7 and a suppressive role for SIRT3 and -4. The scenario is more confusing for SIRT5 and -6, since information is contradictory and scarce. For SIRT1 many inhibitors are available and they seem to hold therapeutic promise in HCC. For the other members the development of specific modulators has just started. This review is aimed to describe the features of SIRTs1-7 in HCC, and the role they play in the onset and progression of the disease. Also, when possible, we will depict the information related to the SIRTs modulators that have been tested in HCC and their possible implication in MDR. With this, we hope to clarify the role of each member in HCC and to shed some light on the most successful strategies to overcome MDR.

NAD+ Homeostasis and NAD+-Consuming Enzymes: Implications for Vascular Health

Nicotinamide adenine dinucleotide (NAD⁺) is a ubiquitous metabolite that takes part in many key redox reactions. NAD⁺ biosynthesis and NAD⁺-consuming enzymes have been attracting markedly increasing interest since they have been demonstrated to be involved in several crucial biological pathways, impacting genes transcription, cellular signaling, and cell cycle regulation. As a consequence, many pathological conditions are associated with an impairment of intracellular NAD⁺ levels, directly or indirectly, which include cardiovascular diseases, obesity, neurodegenerative diseases, cancer, and aging. In this review, we describe the general pathways involved in the NAD⁺ biosynthesis starting from the different precursors, analyzing the actual state-of-art of the administration of NAD⁺ precursors or blocking NAD⁺-dependent enzymes as strategies to increase the intracellular NAD⁺ levels or to counteract the decline in NAD⁺ levels associated with ageing. Subsequently, we focus on the disease-related and age-related alterations of NAD⁺ homeostasis and NAD⁺-dependent enzymes in endothelium and the consequent vascular dysfunction, which significantly contributes to a wide group of pathological disorders.

SIRT2i_Predictor: A Machine Learning-Based Tool to Facilitate the Discovery of Novel SIRT2 Inhibitors

A growing body of preclinical evidence recognized selective sirtuin 2 (SIRT2) inhibitors as novel therapeutics for treatment of age-related diseases. However, none of the SIRT2 inhibitors have reached clinical trials yet. Transformative potential of machine learning (ML) in early stages of drug discovery has been witnessed by widespread adoption of these techniques in recent years. Despite great potential, there is a lack of robust and large-scale ML models for discovery of novel SIRT2 inhibitors. In order to support virtual screening (VS), lead optimization, or facilitate the selection of SIRT2 inhibitors for experimental evaluation, a machine-learning-based tool titled SIRT2i_Predictor was developed. The tool was built on a panel of high-quality ML regression and classification-based models for prediction of inhibitor potency and SIRT1-3 isoform selectivity. State-of-the-art ML algorithms were used to train the models on a large and diverse dataset containing 1797 compounds. Benchmarking against structure-based VS protocol indicated comparable coverage of chemical space with great gain in speed. The tool was applied to screen the in-house database of compounds, corroborating the utility in the prioritization of compounds for costly in vitro screening campaigns. The easy-to-use web-based interface makes SIRT2i_Predictor a convenient tool for the wider community. The SIRT2i_Predictor's source code is made available online.

A Therapeutically Targetable NOTCH1-SIRT1-KAT7 Axis in T-cell Leukemia

T-cell acute lymphoblastic leukemia (T-ALL) is a NOTCH1-driven disease in need of novel therapies. Here, we identify a NOTCH1-SIRT1-KAT7 link as a therapeutic vulnerability in T-ALL, in which the histone deacetylase SIRT1 is overexpressed downstream of a NOTCH1-bound enhancer. SIRT1 loss impaired leukemia generation, whereas SIRT1 overexpression accelerated leukemia and conferred resistance to NOTCH1 inhibition in a deacetylase-dependent manner. Moreover, pharmacologic or genetic inhibition of SIRT1 resulted in significant antileukemic effects. Global acetyl proteomics upon SIRT1 loss uncovered hyperacetylation of KAT7 and BRD1, subunits of a histone acetyltransferase complex targeting H4K12. Metabolic and gene-expression profiling revealed metabolic changes together with a transcriptional signature resembling KAT7 deletion. Consistently, SIRT1 loss resulted in reduced H4K12ac, and overexpression of a nonacetylatable KAT7-mutant partly rescued SIRT1 loss-induced proliferation defects. Overall, our results uncover therapeutic targets in T-ALL and reveal a circular feedback mechanism balancing deacetylase/acetyltransferase activation with potentially broad relevance in cancer.

SIGNIFICANCE

We identify a T-ALL axis whereby NOTCH1 activates SIRT1 through an enhancer region, and SIRT1 deacetylates and activates KAT7. Targeting SIRT1 shows antileukemic effects, partly mediated by KAT7 inactivation. Our results reveal T-ALL therapeutic targets and uncover a rheostat mechanism between deacetylase/acetyltransferase activities with potentially broader cancer relevance. This article is highlighted in the In This Issue feature, p. 1.

Why Is Longevity Still a Scientific Mystery? Sirtuins-Past, Present and Future

The sirtuin system consists of seven highly conserved regulatory enzymes responsible for metabolism, antioxidant protection, and cell cycle regulation. The great interest in sirtuins is associated with the potential impact on life extension. This article summarizes the latest research on the activity of sirtuins and their role in the aging process. The effects of compounds that modulate the activity of sirtuins were discussed, and in numerous studies, their effectiveness was demonstrated. Attention was paid to the role of a caloric restriction and the risks associated with the influence of careless sirtuin modulation on the organism. It has been shown that low modulators' bioavailability/retention time is a crucial problem for optimal regulation of the studied pathways. Therefore, a detailed understanding of the modulator structure and potential reactivity with sirtuins in silico studies should precede in vitro and in vivo experiments. The latest achievements in nanobiotechnology make it possible to create promising molecules, but many of them remain in the sphere of plans and concepts. It seems that solving the mystery of longevity will have to wait for new scientific discoveries.

Inhibiting silence information regulator 2 and glutaminase in the amygdala can improve social behavior in autistic rats

OBJECTIVE

To investigate the underlying molecular mechanisms by which silence information regulator (SIRT) 2 and glutaminase (GLS) in the amygdala regulate social behaviors in autistic rats.

METHODS

Rat models of autism were established by maternal sodium valproic acid (VPA) exposure in wild-type rats and SIRT2-knockout ( SIRT2 -/-) rats. Glutamate (Glu) content, brain weight, and expression levels of SIRT2, GLS proteins and apoptosis-associated proteins in rat amygdala at different developmental stages were examined, and the social behaviors of VPA rats were assessed by a three-chamber test. Then, lentiviral overexpression or interference vectors of GLS were injected into the amygdala of VPA rats. Brain weight, Glu content and expression level of GLS protein were measured, and the social behaviors assessed.

RESULTS

Brain weight, amygdala Glu content and the levels of SIRT2, GLS protein and pro-apoptotic protein caspase-3 in the amygdala were increased in VPA rats, while the level of anti-apoptotic protein Bcl-2 was decreased (all P<0.01). Compared with the wild-type rats, SIRT2 -/- rats displayed decreased expression of SIRT2 and GLS proteins in the amygdala, reduced Glu content, and improved social dysfunction (all P<0.01). Overexpression of GLS increased brain weight and Glu content, and aggravated social dysfunction in VPA rats (all P<0.01). Knockdown of GLS decreased brain weight and Glu content, and improved social dysfunction in VPA rats (all P<0.01).

CONCLUSIONS

The glutamate circulatory system in the amygdala of VPA induced autistic rats is abnormal. This is associated with the upregulation of SIRT2 expression and its induced increase of GLS production; knocking out SIRT2 gene or inhibiting the expression of GLS is helpful in maintaining the balanced glutamate cycle and in improving the social behavior disorder of rats.

Sirtuin 1 in Host Defense during Infection

Sirtuins (SIRTs) are members of the class III histone deacetylase family and epigenetically control multiple target genes to modulate diverse biological responses in cells. Among the SIRTs, SIRT1 is the most well-studied, with a role in the modulation of immune and inflammatory responses following infection. The functions of SIRT1 include orchestrating immune, inflammatory, metabolic, and autophagic responses, all of which are required in establishing and controlling host defenses during infection. In this review, we summarize recent information on the roles of SIRT1 and its regulatory mechanisms during bacterial, viral, and parasitic infections. We also discuss several SIRT1 modulators, as potential antimicrobial treatments. Understanding the function of SIRT1 in balancing immune homeostasis will contribute to the development of new therapeutics for the treatment of infection and inflammatory disease.

The role of Sirtuin 1 in the pathophysiology of polycystic ovary syndrome

Polycystic ovarian syndrome (PCOS) is the most common multifactor heterogeneous endocrine and metabolic disease in women of childbearing age. PCOS is a group of clinical syndromes characterized by reproductive disorders, metabolic disorders, and mental health problems that seriously impact the physical and mental health of patients. At present, new studies suggest that human evolution leads to the body changes and the surrounding environment mismatch adaptation, but the understanding of the disease is still insufficient, the pathogenesis is still unclear. Sirtuin 1 (SIRT1), a member of the Sirtuin family, is expressed in various cells and plays a crucial role in cell energy conversion and physiological metabolism. Pathophysiological processes such as cell proliferation and apoptosis, autophagy, metabolism, inflammation, antioxidant stress and insulin resistance play a crucial role. Moreover, SIRT1 participates in the pathophysiological processes of oxidative stress, autophagy, ovulation disturbance and insulin resistance, which may be a vital link in the occurrence of PCOS. Hence, the study of the role of SIRT1 in the pathogenesis of PCOS and related complications will contribute to a more thorough understanding of the pathogenesis of PCOS and supply a basis for the treatment of patients.

Additive pharmacological interaction between sirtuin inhibitor cambinol and paclitaxel in MCF7 luminal and MDA-MB-231 triple-negative breast cancer cells

Background

Breast cancer (BC) is the most common malignancy and the leading cause of cancer-related death in women worldwide. Sirtuin inhibitors (SIRTi), belonging to the histone deacetylase inhibitors group (HDIs), are potent epigenetic drugs that have been investigated for therapeutic use in different clinical disorders, including hematological malignancies and solid tumors.

Methods

The influence of cambinol (CAM; SIRTi) used individually or in combination with standard chemotherapeutic paclitaxel (PAX) on viability (MTT assay), proliferation (BrdU assay), induction of apoptosis and cell cycle arrest (FACS analysis) was determined in MCF7 luminal and MDA-MB-231 triple-negative breast cancer (TNBC) cells. The types of pharmacological drug–drug interaction between CAM and PAX were determined by an exact and rigorous pharmacodynamic method—an isobolography, to determine the presence of synergism, addition or antagonism between analyzed drugs using a variety of fixed-dose ratios.

Results

The combination of CAM and PAX at a fixed ratio of 1:1 exerted additive interaction in the viability of MCF7 and MDA-MB-231 BC cells. Both active agents used separately reduced viability and proliferation of BC cells as well as induced apoptosis and cell cycle arrest. These effects were much more evident in MCF7 than in MDA-MB-231 BC cells. Additionally, CAM combined with PAX increased anti-cancer activity compared to PAX used alone.

Conclusion

CAM might be considered a potential therapeutic agent individually or in combined therapy with PAX against luminal or TNBC.

Graphical abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s43440-022-00393-w.

Sirtuins: Research advances on the therapeutic role in acute kidney injury

BACKGROUND

Acute kidney injury (AKI), a common multidisciplinary diagnostic clinical critical illness, eventually causes end-stage renal disease (ESRD). Although many clinical measures have been taken to prevent or treat AKI, high morbidity and death rates were recorded. Therefore, in-depth pathogenesis study and search for new therapeutic targets are in demand. Interestingly, the suirtuins family showed a significant protective effect in AKI. Sirtuins (SIRT1-7) is a family of seven proteins with NAD⁺-dependent type III histone deacetylase activity. Sirtuins family members were involved by AKI, and regulation of sirtuins activities significantly improved AKI-induced renal injury. Therefore, the therapeutic role and molecular mechanisms of the sirtuins family in AKI has important research implications for clinical applications or basic research.

PURPOSE

This review summarizes recent advances in the roles and functions of the sirtuins family, discusses their therapeutic effects on AKI and related molecular mechanisms, and the mechanisms of action of small molecule specific activators or inhibitors sirtuins in the prevention and treatment of AKI were discussed.

METHODS

The data in this review were retrieved from various scientific databases (PubMed, Google scholar, Science Direct, and Web of Science), till December 2021. The keywords were used as follows: "Sirtuins", "Acute kidney injury", "AKI", "Sirtuins modulators" and "Histone deacetylation". The retrieved data followed PRISMA criteria (preferred reporting items for systematic review).

RESULTS

Growing evidence indicates that members of the sirtuins family regulate the development and progression of different renal diseases, including AKI, through anti-inflammation, antioxidation, anti-apoptotic, and maintenance of mitochondrial homeostasis. The molecular mechanism of Sirtuins family on AKI mainly regulated NF-κB, JNK/ERK, and AMPK/mTOR signaling pathways, upregulated the expression of PGC-1α, HO-1, NRF2, Bcl-2, OPA1, and AMPK, and downregulated the expression of NRLP3, IL-1β, TNF-α, IL-6, ROS, MFF, Drp1, Bax, ERK, and mTOR. In addition, the active ingredients of herbs (resveratrol, thujaplicins, huperzine, and curcumin) could activate the activity of SIRT1 or SIRT3, thereby improving AKI. Meanwhile, the synthetic Sirtuins inhibitor (AK-1) inhibited SIRT2 activity, thus alleviating AKI. In the future, more specific modulators will remain needed to enhance the clinical therapeutic role of the Sirtuins family in AKI.

CONCLUSION

The sirtuins family is a promising type III histone deacetylase for AKI treatment. This review will provide insight into sirtuins family's therapeutic role in AKI and promote the clinical use of sirtuins modulators in AKI.

New Synthetic Analogues of Natural Polyphenols as Sirtuin 1-Activating Compounds

NAD⁺-dependent deacetylase SIRT1 regulates many different biological processes, thus being involved in pathogenic conditions such as metabolic diseases, neurogenerative disorders and cancer. Notably, experimental evidence underlined that the activation of SIRT1 had promising cardioprotective effects. Consequently, many efforts have been so far devoted to finding new SIRT1 activators, both derived from natural sources or prepared by synthetic procedures. Herein, we discovered new SIRT1-activating derivatives, characterized by phenolic rings spaced by sulfur, nitrogen or oxygen-based central linkers. The newly synthesized derivatives were analyzed in enzymatic assays to determine their ability to activate SIRT1, as compared with that of resveratrol. Among the tested molecules, bisarylaniline compound 10 proved to be the most efficient SIRT1 activator. An evaluation of the effects caused by focused structural variations revealed that its para-hydroxy-substituted diphenyl moiety of 10 was the fundamental structural requirement for achieving good SIRT1 activation. Compound 10 was further investigated in ex vivo studies in isolated and perfused rat hearts submitted to ischemia/reperfusion (I/R), where it showed significant protection of the myocardium against I/R injury. Molecular modeling studies suggest the binding mode of 10 within SIRT1 in the presence of the p53-AMC peptide. Our findings reveal that this chemical scaffold may be used as the starting point to develop a new class of more potent SIRT1 activators as cardioprotective agents.

The CD38 glycohydrolase and the NAD sink: implications for pathological conditions

Nicotinamide adenine dinucleotide (NAD) acts as a cofactor in several oxidation-reduction (redox) reactions and is a substrate for a number of nonredox enzymes. NAD is fundamental to a variety of cellular processes including energy metabolism, cell signaling, and epigenetics. NAD homeostasis appears to be of paramount importance to health span and longevity, and its dysregulation is associated with multiple diseases. NAD metabolism is dynamic and maintained by synthesis and degradation. The enzyme CD38, one of the main NAD-consuming enzymes, is a key component of NAD homeostasis. The majority of CD38 is localized in the plasma membrane with its catalytic domain facing the extracellular environment, likely for the purpose of controlling systemic levels of NAD. Several cell types express CD38, but its expression predominates on endothelial cells and immune cells capable of infiltrating organs and tissues. Here we review potential roles of CD38 in health and disease and postulate ways in which CD38 dysregulation causes changes in NAD homeostasis and contributes to the pathophysiology of multiple conditions. Indeed, in animal models the development of infectious diseases, autoimmune disorders, fibrosis, metabolic diseases, and age-associated diseases including cancer, heart disease, and neurodegeneration are associated with altered CD38 enzymatic activity. Many of these conditions are modified in CD38-deficient mice or by blocking CD38 NADase activity. In diseases in which CD38 appears to play a role, CD38-dependent NAD decline is often a common denominator of pathophysiology. Thus, understanding dysregulation of NAD homeostasis by CD38 may open new avenues for the treatment of human diseases.

Redox Homeostasis in Cardiovascular Disease: The Role of Mitochondrial Sirtuins

Cardiovascular disease (CVD) is still the leading cause of death worldwide. Despite successful advances in both pharmacological and lifestyle strategies to fight well-established risk factors, the burden of CVD is still increasing. Therefore, it is necessary to further deepen our knowledge of the pathogenesis of the disease for developing novel therapies to limit even more its related morbidity and mortality. Oxidative stress has been identified as a common trait of several manifestations of CVD and could be a promising target for innovative treatments. Mitochondria are a major source of oxidative stress and sirtuins are a family of enzymes that generate different post-translational protein modifications, thus regulating important cellular processes, including cell cycle, autophagy, gene expression, and others. In particular, three sirtuins, SIRT3, SIRT4, and SIRT5 are located within the mitochondrial matrix where they regulate energy production and antioxidant pathways. Therefore, these sirtuins are strongly involved in the balance between oxidant and antioxidant mechanisms. In this review, we summarize the activities of these sirtuins with a special focus on their role in the control of oxidative stress, in relation to energy metabolism, atherosclerosis, and CVD.