Negative control of p53 by Sir2alpha promotes cell survival under stress

SIRT1: a novel regulator in colorectal cancer

The class-III histone deacetylase SIRT1 is the most extensively investigated sirtuin deacetylase. It is resistant to the broad deacetylase inhibitor trichostatin A and depends on oxidized nicotinamide adenine nucleotide (NAD+). SIRT1 plays a crucial role in the tumorigenesis of numerous types of cancers, including colorectal cancer (CRC). Accumulating evidence indicates that SIRT1 is a therapeutic target for CRC; however, the function and underlying mechanism of SIRT1 in CRC still need to be elucidated. Herein, we provide a detailed and updated review to illustrate that SIRT1 regulates many processes that go awry in CRC cells, such as apoptosis, autophagy, proliferation, migration, invasion, metastasis, oxidative stress, resistance to chemo-radio therapy, immune evasion, and metabolic reprogramming. Moreover, we closely link our review to the clinical practice of CRC treatment, summarizing the mechanisms and prospects of SIRT1 inhibitors in CRC therapy. SIRT1 inhibitors as monotherapy in CRC or in combination with chemotherapy, radiotherapy, and immune therapies are comprehensively discussed. From epigenetic regulation to its potential therapeutic effect, we hope to offer novel insights and a comprehensive understanding of SIRT1's role in CRC.

Nicotinamide protects against diabetic kidney disease through regulation of Sirt1

PURPOSE

To investigate the effect of nicotinamide (Nam) on diabetic kidney disease (DKD) in mice and explore its mechanism.

METHODS

Thirty DBA/2 J mice were randomly assigned to three groups. After 8 weeks of hyperglycemia induced by streptozocin (STZ), Nam and saline were administrated to STZ + Nam and STZ + NS mice, respectively, for 8 weeks. Non-diabetic mice (NDM) were used as control group. Twenty In2-/- Akita mice were randomly divided into two groups. After 8 weeks of hyperglycemia, Nam and saline were administered to Akita + Nam and Akita + NS mice, respectively, for 6 weeks. Wild-type littermates were used as control group. Markers of renal injury were analyzed, and the molecular mechanisms were explored in human proximal tubular HK2 cells.

RESULTS

Urinary albumin-to-creatinine ratio (UACR) and kidney injury molecule 1 (KIM-1) decreased in the STZ + Nam and Akita + Nam groups. Pathological analysis showed that Nam improved the structure of glomerular basement membrane, ameliorated glomerular sclerosis, and decreased the accumulation of extracellular matrix and collagen. Compared to the diabetic control group, renal fibrosis, inflammation, and oxidative stress were reduced in the Nam-treated mice. The expression of sirtuin 1 (Sirt1) in human proximal tubular HK2 cells was inhibited by high glucose and Nam treatment enhanced its expression. However, in HK2 cells with Sirt1 knockdown, the protective effect of Nam was abolished, indicating that the beneficial effect of Nam was partially dependent on Sirt1.

CONCLUSIONS

Nam has a renoprotective effect against renal injury caused by hyperglycemia and may be a potential target for the treatment of DKD.

Enhanced upregulation of SIRT1 via pioglitazone and ligustrazine confers protection against ethanol-induced gastric ulcer in rats

Gastric ulcer is a disturbing disease that impacts many people worldwide. Pioglitazone (Piog), a thiazolidinedione, and ligustrazine (Ligu), a natural component of Ligusticum chuanxiong possess gastroprotective properties. However, the underlying mechanism is not well elucidated. The present study aimed to investigate the gastroprotective effects of Piog (15 mg/kg, p.o.), Ligu (15 mg/kg, p.o.), and their combination against ethanol-induced gastric ulcer in rats. Omeprazole (10 mg/kg) was used as a standard. Pre-treatment for 7 days with Piog, Ligu, and (Piog+Ligu) effectively alleviated ethanol-predisposed oxidative stress and inflammation through restoring HO-1, GSH, and SOD tissue levels and decreasing elevated MDA, TNF-α, ICAM, I-NOS, and IL-1β contents. Moreover, Piog, Ligu, and (Piog+Ligu) markedly inhibited the ethanol-induced increase of gastric NF-KB and BAX. In contrast, this pre-treatment regimen significantly accelerated protein expression of SIRT1, Nrf2, and Bcl-2, along with autophagic proteins, ATG5 and Beclin. Interestingly, macroscopic, histopathological examination and mucin content were in harmony with previous results, where pre-treatment with Piog, Ligu, and (Piog+Ligu) showed a declined mucosal injury as evidenced by the remarkable decrease of the ulcer area percentage by 62.3%, 38.7%, and 91.2%, respectively, compared to the ethanol-ulcerated group. In conclusion, Piog and Ligu exhibited remarkable gastroprotective properties. Our study was the first to show that Piog, Ligu, and (Piog+Ligu) ameliorated oxidative stress, inflammation, and apoptosis and accelerated the autophagic process via the upregulation of the upstream SIRT1 protein. It is worth mentioning that future studies are needed to pave the way for the clinical use of Piog and Ligu as gastro-protective agents.

Targeting POLD1 to suppress the proliferation and migration of breast cancer MDA-MB-231 cell lines by downregulation of SIRT1

Background

The resistant and aggressive nature of triple-negative breast cancer (TNBC) renders it mostly incurable even following extensive multimodal treatment. Therefore, more studies are required to understand the underlying molecular mechanisms of its pathogenesis. SIRT1 is a class III histone deacetylase NAD + -dependent enzyme that is interlinked in tumor progression, apoptosis, metastasis, and other mechanisms of tumorigenesis, while DNA polymerase delta 1 (POLD1) functions as a gene coding for p125, which plays an important role in genome stability and DNA replication.

Objective

We aimed to investigate the downstream signaling pathway of EX-527, a potent and selective SIRT1 inhibitor, in MDA-MB-231 breast cancer cell lines, and the crosstalk between SIRT1 and POLD1, which is essential for the activities of polymerase δ.

Methods

The antiproliferative and apoptotic effects of EX-527 on MDA-MB-231 cells were assessed by MTT and annexin V/PI double staining assays. Migration and invasion activity of MDA-MB-231 cells were assessed by wound-healing scratch and transwell assays. Protein expressions were examined using Western Blot analysis.

Results

MDA-MB-231 cells treatment with IC50 values of 45.3 μM EX-527 significantly suppressed cell proliferation and induced apoptosis by down-regulating SIRT1. Also, it significantly repressed migration and invasion of MDA-MB-231 cells as evaluated by wound healing and transwell invasion assays. Western blot results showed that decreased expression of SIRT1 is positively correlated with expression of p53 along with down-regulating POLD1.

Conclusion

SIRT1 could have an oncogenic role in breast cancer development and progression via activating POLD1. These conclusions present new insights into the underlying mechanisms of TNBC.

Caloric and time restriction diets improve acute kidney injury in experimental menopausal rats: role of silent information regulator 2 homolog 1 and transforming growth factor beta 1

BACKGROUND

Estrogen has a protective impact on acute kidney injury (AKI); moreover, reducing the daily intake of calories impedes developing diseases. The present study aimed to determine the effects of calorie restriction (CR) and time restriction (TR) diets on the expression of silent information regulator 2 homolog 1 (SIRT1), transforming growth factor beta 1 (TGF-β1), and other indicators in the presence and absence of ovaries in AKI female rats.

METHODS

The female rats were divided into two groups, ovariectomized (OVX) and sham, and were placed on CR and TR diets for eight weeks; afterward, AKI was induced by injecting glycerol, and kidney injury indicators and biochemical parameters were measured before and after AKI.

RESULTS

After AKI, the levels of urine albumin excretion rate, urea, and creatinine in serum, and TGF-β1 increased, while creatinine clearance and SIRT1 decreased in kidney tissue. CR improved kidney indicators and caused a reduction in TGF-β1 and an increase in SIRT1 in ovary-intact rats. Moreover, CR prevented total antioxidant capacity (TAC) decrease and malondialdehyde (MDA) increase resulting from AKI. Before AKI, an increase in body weight, fasting blood sugar (FBS), low-density lipoprotein (LDL), triglyceride (TG), and total cholesterol (TC), and a decrease in high-density lipoprotein (HDL) were observed in OVX rats compared to sham rats, but CR prevented these changes. The effects of TR were similar to those of CR in all indicators except for TGF-β1, SIRT1, urea, creatinine, and albumin.

CONCLUSION

The present study indicated that CR is more effective than TR in preventing AKI, probably by increasing SIRT1 and decreasing TGF-β1 in ovary-intact animals.

Search for protein kinase(s) related to cell growth or viability maintenance in the presence of ethanol in budding and fission yeasts

Alcohol fermentation comprises two phases: phase 1, alcohol fermentation occurs while yeast cells proliferate; phase 2, growth stops and alcohol fermentation continues. We categorized genes related to proliferation in low ethanol (phase 1) and viability in high ethanol (phase 2) as Alcohol Growth Ability (AGA) and Alcohol Viability (ALV), respectively. Although genes required for phase 1 are examined in budding yeast, those for phase 2 are unknown. We set conditions for ALV screening, searched for protein kinases (PKs) related to ALV in budding yeast, and expanded two screenings to fission yeast. Bub1 kinase was important for proliferation in low ethanol but not for viability in high ethanol, suggesting that the important PKs differ between the two phases. It was indeed the case. Further, 3 common PKs were identified as AGA in both yeasts, suggesting that the important cellular mechanism in phase 1 is conserved in both yeasts, at least partially.

MDM2 accelerated renal senescence via ubiquitination and degradation of HDAC1

Senescence, an intricate and inevitable biological process, characterized by the gradual loss of homeostasis and declining organ functions. The pathological features of cellular senescence, including cell cycle arrest, metabolic disruptions, and the emergence of senescence-associated secretory phenotypes (SASP), collectively contribute to the intricate and multifaceted nature of senescence. Beyond its classical interaction with p53, murine double minute gene 2 (MDM2), traditionally known as an E3 ubiquitin ligase involved in protein degradation, plays a pivotal role in cellular processes governing senescence. Histone deacetylase (HDAC), a class of histone deacetylases mainly expressed in the nucleus, has emerged as a critical contributor to renal tissues senescence. In this study we investigated the interplay between MDM2 and HDAC1 in renal senescence. We established a natural aging model in mice over a 2-year period that was verified by SA-β-GAL staining and increased expression of senescence-associated markers such as p21, p16, and TNF-α in the kidneys. Furthermore, we showed that the expression of MDM2 was markedly increased, while HDAC1 expression underwent downregulation during renal senescence. This phenomenon was confirmed in H2O2-stimulated HK2 cells in vitro. Knockout of renal tubular MDM2 alleviated renal senescence in aged mice and in H2O2-stimulated HK2 cells. Moreover, we demonstrated that MDM2 promoted renal senescence by orchestrating the ubiquitination and subsequent degradation of HDAC1. These mechanisms synergistically accelerate the aging process in renal tissues, highlighting the intricate interplay between MDM2 and HDAC1, underpinning the age-related organ function decline.

Megraw T, Ghaedi K. PPARgamma dependent PEX11beta counteracts the suppressive role of SIRT1 on neural differentiation of HESCs

The membrane peroxisomal proteins PEX11, play a crucial role in peroxisome proliferation by regulating elongation, membrane constriction, and fission of pre-existing peroxisomes. In this study, we evaluated the function of PEX11B gene in neural differentiation of human embryonic stem cell (hESC) by inducing shRNAi-mediated knockdown of PEX11B expression. Our results demonstrate that loss of PEX11B expression led to a significant decrease in the expression of peroxisomal-related genes including ACOX1, PMP70, PEX1, and PEX7, as well as neural tube-like structures and neuronal markers. Inhibition of SIRT1 using pharmacological agents counteracted the effects of PEX11B knockdown, resulting in a relative increase in PEX11B expression and an increase in differentiated neural tube-like structures. However, the neuroprotective effects of SIRT1 were eliminated by PPAR inhibition, indicating that PPARɣ may mediate the interaction between PEX11B and SIRT1. Our findings suggest that both SIRT1 and PPARɣ have neuroprotective effects, and also this study provides the first indication for a potential interaction between PEX11B, SIRT1, and PPARɣ during hESC neural differentiation.

Research progress on Sirtuins (SIRTs) family modulators

Sirtuins (SIRTs) represent a class of nicotinamide adenine dinucleotide (NAD+)-dependent protein deacetylases that exert a crucial role in cellular signal transduction and various biological processes. The mammalian sirtuins family encompasses SIRT1 to SIRT7, exhibiting therapeutic potential in counteracting cellular aging, modulating metabolism, responding to oxidative stress, inhibiting tumors, and improving cellular microenvironment. These enzymes are intricately linked to the occurrence and treatment of diverse pathological conditions, including cancer, autoimmune diseases, and cardiovascular disorders. Given the significance of histone modification in gene expression and chromatin structure, maintaining the equilibrium of the sirtuins family is imperative for disease prevention and health restoration. Mounting evidence suggests that modulators of SIRTs play a crucial role in treating various diseases and maintaining physiological balance. This review delves into the molecular structure and regulatory functions of the sirtuins family, reviews the classification and historical evolution of SIRTs modulators, offers a systematic overview of existing SIRTs modulation strategies, and elucidates the regulatory mechanisms of SIRTs modulators (agonists and inhibitors) and their clinical applications. The article concludes by summarizing the challenges encountered in SIRTs modulator research and offering insights into future research directions.

Sirtuins and Cellular Senescence in Patients with Idiopathic Pulmonary Fibrosis and Systemic Autoimmune Disorders

The sirtuin family is a heterogeneous group of proteins that play a critical role in many cellular activities. Several degenerative diseases have recently been linked to aberrant sirtuin expression and activity because of the involvement of sirtuins in maintaining cell longevity and their putative antiaging function. Idiopathic pulmonary fibrosis and progressive pulmonary fibrosis associated with systemic autoimmune disorders are severe diseases characterized by premature and accelerated exhaustion and failure of alveolar type II cells combined with aberrant activation of fibroblast proliferative pathways leading to dramatic destruction of lung architecture. The mechanisms underlying alveolar type II cell exhaustion in these disorders are not fully understood. In this review, we have focused on the role of sirtuins in the pathogenesis of idiopathic and secondary pulmonary fibrosis and their potential as biomarkers in the diagnosis and management of fibrotic interstitial lung diseases.

CD38 Deficiency Protects Mouse Retinal Ganglion Cells Through Activating the NAD+/Sirt1 Pathway in Ischemia-Reperfusion and Optic Nerve Crush Models

Purpose

The purpose of this study was to investigate the protective effect of CD38 deletion on retinal ganglion cells (RGCs) in a mouse retinal ischemia/reperfusion (I/R) model and an optic nerve crush (ONC) model, and to elucidate the underlying molecular mechanisms.

Methods

Retinal I/R and ONC models were constructed in mice. PCR was used to identify the deletion of CD38 gene in mice, hematoxylin and eosin (H&E) staining was used to evaluate the changes in retinal morphology, and electroretinogram (ERG) was used to evaluate the changes in retinal function. The survival of RGCs and activation of retinal macroglia were evaluated by immunofluorescence staining. The expression of Sirt1, CD38, Ac-p65, Ac-p53, TNF-α, IL-1β, and Caspase3 proteins in the retina was further evaluated by protein imprinting.

Results

In retinal I/R and ONC models, CD38 deficiency reduced the loss of RGCs and activation of macroglia and protected the retinal function. CD38 deficiency increased the concentration of NAD+, reduced the degree of acetylation of NF-κB p65 and p53, and reduced expression of the downstream inflammatory cytokines TNFα, IL-1β, and apoptotic protein Caspase3 in the retina in the ONC model. Intraperitoneal injection of the Sirt1 inhibitor EX-527 partially counteracted the effects of CD38 deficiency, suggesting that CD38 deficiency acts at least in part through the NAD+/Sirt1 pathway.

Conclusions

CD38 plays an important role in the pathogenesis of retinal I/R and ONC injury. CD38 deletion protects RGCs by attenuating inflammatory responses and apoptosis through the NAD+/Sirt1 pathway.

Development and validation of an LC-MS/MS method for quantifying NAD+ and related metabolites in mice sciatic nerves and its application to a nerve injury animal model

Recent studies highlight the pivotal roles of Nicotinamide adenine dinucleotide (NAD+) and its metabolites in aging and neurodegeneration. Accurate quantification of NAD+ and its metabolite levels in cells or tissues is crucial for advancing biochemical research and interventions targeting aging and neurodegenerative diseases. This study presents an accurate, precise, and rapid LC-MS/MS method using a surrogate matrix to quantify endogenous substances NAD+, nicotinamide mononucleotide (NMN), nicotinamide (NAM), adenosine diphosphate ribose (ADPR), and cyclic adenosine diphosphate ribose (cADPR) concentrations in mice sciatic nerves. Considering the properties of the phosphate groups in the analytes, the column and mobile phase were systematically optimized. These five polar analytes exhibited excellent analytical performance and baseline separation within 5 min on an Atlantis Premier BEH C18 AX column, with methylene phosphonic acid as a mobile phase additive. Enhanced sensitivity addressed the challenges posed by the small sample size of mice sciatic nerve and low NMN and cADPR detection. The method was fully validated, with linear correlation coefficients exceeding 0.992, precision (%relative standard deviation, RSD) values within 8.8%, and accuracy values between 92.2% and 107.3%, suggesting good reproducibility. Analytical recoveries in spiked and diluted matrix ranged from 87.8% to 104.7%, indicating the suitability of water as a surrogate matrix. Application of the method to quantify NAD+ and its metabolite levels in normal and injured mice sciatic nerve identified cADPR as a sensitive biomarker in the nerve injury model. This method is anticipated to deepen our understanding of the connections between NAD+ and its metabolites in health and disease, potentially improving diagnoses of various neurological disorders and aiding drug development for aging and neurodegenerative diseases.

Irradiated riboflavin over nonradiated one: Potent antimigratory, antiproliferative and cytotoxic effects on glioblastoma cells

Riboflavin is a water-soluble yellowish vitamin and is controversial regarding its effect on tumour cells. Riboflavin is a powerful photosensitizer that upon exposure to radiation, undergoes an intersystem conversion with molecular oxygen, leading to the production of ROS. In the current study, we sought to ascertain the impact of irradiated riboflavin on C6 glioblastoma cells regarding proliferation, cell death, oxidative stress and migration. First, we compared the proliferative behaviour of cells following nonradiated and radiated riboflavin. Next, we performed apoptotic assays including Annexin V and caspase 3, 7 and 9 assays. Then we checked on oxidative stress and status by flow cytometry and ELISA kits. Finally, we examined inflammatory change and levels of MMP2 and SIRT1 proteins. We caught a clear antiproliferative and cytotoxic effect of irradiated riboflavin compared to nonradiated one. Therefore, we proceeded with our experiments using radiated riboflavin. In all apoptotic assays, we observed a dose-dependent increase. Additionally, the levels of oxidants were found to increase, while antioxidant levels decreased following riboflavin treatment. In the inflammation analysis, we observed elevated levels of both pro-inflammatory and anti-inflammatory cytokines. Additionally, after treatment, we observed reduced levels of MMP2 and SIRT. In conclusion, radiated riboflavin clearly demonstrates superior antiproliferative and apoptotic effects on C6 cells at lower doses compared to nonradiated riboflavin.

Role of sirtuins in epigenetic regulation and aging control

Advances in modern healthcare in developed countries make it possible to extend the human lifespan, which is why maintaining active longevity is becoming increasingly important. After the sirtuin (SIRT) protein family was discovered, it started to be considered as a significant regulator of the physiological processes associated with aging. SIRT has deacetylase, deacylase, and ADP-ribosyltransferase activity and modifies a variety of protein substrates, including chromatin components and regulatory proteins. This multifactorial regulatory system affects many processes: cellular metabolism, mitochondrial functions, epigenetic regulation, DNA repair and more. As is expected, the activity of sirtuin proteins affects the manifestation of classic signs of aging in the body, such as cellular senescence, metabolic disorders, mitochondrial dysfunction, genomic instability, and the disruption of epigenetic regulation. Changes in the SIRT activity in human cells can also be considered a marker of aging and are involved in the genesis of various age-dependent disorders. Additionally, experimental data obtained in animal models, as well as data from population genomic studies, suggest a SIRT effect on life expectancy. At the same time, the diversity of sirtuin functions and biochemical substrates makes it extremely complicated to identify cause-and-effect relationships and the direct role of SIRT in controlling the functional state of the body. However, the SIRT influence on the epigenetic regulation of gene expression during the aging process and the development of disorders is one of the most important aspects of maintaining the homeostasis of organs and tissues. The presented review centers on the diversity of SIRT in humans and model animals. In addition to a brief description of the main SIRT enzymatic and biological activity, the review discusses its role in the epigenetic regulation of chromatin structure, including the context of the development of genome instability associated with aging. Studies on the functional connection between SIRT and longevity, as well as its effect on pathological processes associated with aging, such as chronic inflammation, fibrosis, and neuroinflammation, have been critically analyzed.

Current Trends in Sirtuin Activator and Inhibitor Development

Sirtuins are NAD+-dependent protein deacylases and key metabolic regulators, coupling the cellular energy state with selective lysine deacylation to regulate many downstream cellular processes. Humans encode seven sirtuin isoforms (Sirt1-7) with diverse subcellular localization and deacylase targets. Sirtuins are considered protective anti-aging proteins since increased sirtuin activity is canonically associated with lifespan extension and decreased activity with developing aging-related diseases. However, sirtuins can also assume detrimental cellular roles where increased activity contributes to pathophysiology. Modulation of sirtuin activity by activators and inhibitors thus holds substantial potential for defining the cellular roles of sirtuins in health and disease and developing therapeutics. Instead of being comprehensive, this review discusses the well-characterized sirtuin activators and inhibitors available to date, particularly those with demonstrated selectivity, potency, and cellular activity. This review also provides recommendations regarding the best-in-class sirtuin activators and inhibitors for practical research as sirtuin modulator discovery and refinement evolve.

Genetic insights into bladder cancer: the impact of SIRT1 gene polymorphism

Bladder cancer (BC) has shown a significant global health concern with distinct pathological, genetic, and epigenetic characteristics. Its prevalence is influenced by various risk factors, including age, gender, and genetic predisposition. This study investigates the association between BC and the Sirtuin 1 (SIRT1) gene polymorphism rs369274325 in the Turkish population. Genomic DNA was isolated from peripheral blood samples and genotyping of rs369274325 polymorphism in SIRT 1 was investigated in 200 individuals (in 100 Turkish bladder cancer patients and 100 healthy individuals as the control group.) by real-time PCR. Demographic information, smoking and alcohol consumption status was analyzed by statistical analysis. Statistical analysis was performed by Pearson's Chi-square test. Smoking and alcohol consumption were significantly higher in BC patients compared to controls (p < 0.00018 and p < 0.0001, respectively). The genotypic distribution of SIRT1 rs369274325 did not show a significant difference between BC patients and controls (p = 0.5550). BC, influenced by genetic and environmental factors, has been linked to various gene mutations. SIRT1, involved in diverse physiological processes, is proposed to play a role in BC. However, our study did not find a significant association between SIRT1 rs369274325 polymorphism and BC in the Turkish population.

Protection against cancer therapy-induced cardiovascular injury by planed-derived polyphenols and nanomaterials

Cancer therapy-induced heart injury is a significant concern for cancer patients undergoing chemotherapy, radiotherapy, immunotherapy, and also targeted molecular therapy. The use of these treatments can lead to oxidative stress and cardiomyocyte damage in the heart, which can result in heart failure and other cardiac complications. Experimental studies have revealed that chemotherapy drugs such as doxorubicin and cyclophosphamide can cause severe side effects such as cardiac fibrosis, electrophysiological remodeling, chronic oxidative stress and inflammation, etc., which may increase risk of cardiac disorders and attacks for patients that underwent chemotherapy. Similar consequences may also be observed for patients that undergo radiotherapy for left breast or lung malignancies. Polyphenols, a group of natural compounds with antioxidant and anti-inflammatory properties, have shown the potential in protecting against cancer therapy-induced heart injury. These compounds have been found to reduce oxidative stress, necrosis and apoptosis in the heart, thereby preserving cardiac function. In recent years, nanoparticles loaded with polyphenols have also provided for the delivery of these compounds and increasing their efficacy in different organs. These nanoparticles can improve the bioavailability and efficacy of polyphenols while minimizing their toxicity. This review article summarizes the current understanding of the protective effects of polyphenols and nanoparticles loaded with polyphenols against cancer therapy-induced heart injury. The article discusses the mechanisms by which polyphenols protect the heart, including antioxidant and anti-inflammation abilities. The article also highlights the potential benefits of using nanoparticles for the delivery of polyphenols.

Inherited myogenic abilities in muscle precursor cells defined by the mitochondrial complex I-encoding protein

Skeletal muscle comprises different muscle fibers, including slow- and fast-type muscles, and satellite cells (SCs), which exist in individual muscle fibers and possess different myogenic properties. Previously, we reported that myoblasts (MBs) from slow-type enriched soleus (SOL) had a high potential to self-renew compared with cells derived from fast-type enriched tibialis anterior (TA). However, whether the functionality of myogenic cells in adult muscles is attributed to the muscle fiber in which they reside and whether the characteristics of myogenic cells derived from slow- and fast-type fibers can be distinguished at the genetic level remain unknown. Global gene expression analysis revealed that the myogenic potential of MBs was independent of the muscle fiber type they reside in but dependent on the region of muscles they are derived from. Thus, in this study, proteomic analysis was conducted to clarify the molecular differences between MBs derived from TA and SOL. NADH dehydrogenase (ubiquinone) iron-sulfur protein 8 (Ndufs8), a subunit of NADH dehydrogenase in mitochondrial complex I, significantly increased in SOL-derived MBs compared with that in TA-derived cells. Moreover, the expression level of Ndufs8 in MBs significantly decreased with age. Gain- and loss-of-function experiments revealed that Ndufs8 expression in MBs promoted differentiation, self-renewal, and apoptosis resistance. In particular, Ndufs8 suppression in MBs increased p53 acetylation, followed by a decline in NAD/NADH ratio. Nicotinamide mononucleotide treatment, which restores the intracellular NAD+ level, could decrease p53 acetylation and increase myogenic cell self-renewal ability in vivo. These results suggested that the functional differences in MBs derived from SOL and TA governed by the mitochondrial complex I-encoding gene reflect the magnitude of the decline in SC number observed with aging, indicating that the replenishment of NAD+ is a possible approach for improving impaired cellular functions caused by aging or diseases.

SIRT1 and HSP90α feed-forward circuit safeguards chromosome segregation integrity in diffuse large B cell lymphomas

Diffuse large B-cell lymphoma (DLBCL) is the most common aggressive non-Hodgkin lymphoma in adults, exhibiting highly heterogenous clinical behavior and complex molecular background. In addition to the genetic complexity, different DLBCL subsets exhibit phenotypic features independent of the genetic background. For example, a subset of DLBCLs is distinguished by increased oxidative phosphorylation and unique transcriptional features, including overexpression of certain mitochondrial genes and a molecular chaperone, heat shock protein HSP90α (termed "OxPhos" DLBCLs). In this study, we identified a feed-forward pathogenetic circuit linking HSP90α and SIRT1 in OxPhos DLBCLs. The expression of the inducible HSP90α isoform remains under SIRT1-mediated regulation. SIRT1 knockdown or chemical inhibition reduced HSP90α expression in a mechanism involving HSF1 transcription factor, whereas HSP90 inhibition reduced SIRT1 protein stability, indicating that HSP90 chaperones SIRT1. SIRT1-HSP90α interaction in DLBCL cells was confirmed by co-immunoprecipitation and proximity ligation assay (PLA). The number of SIRT1-HSP90α complexes in PLA was significantly higher in OxPhos- dependent than -independent cells. Importantly, SIRT1-HSP90α interactions in OxPhos DLBCLs markedly increased in mitosis, suggesting a specific role of the complex during this cell cycle phase. RNAi-mediated and chemical inhibition of SIRT1 and/or HSP90 significantly increased the number of cells with chromosome segregation errors (multipolar spindle formation, anaphase bridges and lagging chromosomes). Finally, chemical SIRT1 inhibitors induced dose-dependent cytotoxicity in OxPhos-dependent DLBCL cell lines and synergized with the HSP90 inhibitor. Taken together, our findings define a new OxPhos-DLBCL-specific pathogenetic loop involving SIRT1 and HSP90α that regulates chromosome dynamics during mitosis and may be exploited therapeutically.

Astilbin targeted Sirt1 to inhibit acetylation of Nrf2 to alleviate grass carp hepatocyte apoptosis caused by PCB126-induced mitochondrial kinetic and metabolism dysfunctions

3, 3', 4, 4', 5-pentachlorobiphenyl (PCB126) is extensively utilized in electronic products, lubricant, and insecticide due to its excellent chemical stability and insulation prosperity, resulting in its frequent detection in environment. In addition, atmospheric deposition, as well as industrial and urban wastewater discharge can also lead to PCB126 contamination in marine environment, triggering damages to the tissues of aquatic organisms through oxidative stress. Astilbin is a type of flavonoid compound found in plants that plays a crucial role in providing powerful antioxidant and anti-inflammatory properties. In this study, we aimed to investigate the specific mechanism of PCB126-induced damage and the potential protective effect of Astilbin. To achieve this, we treated grass carp hepatocytes (L8824) with 75 μM PCB126 and/or 0.5 mM Astilbin for 24 h and used experimental methods such as Flow cytometry, molecular docking, PPI analysis, detection of commercial kits (ATP concentration and ATPnase activity) and measurement of mitochondrial membrane potential (ΔΨm). Our findings revealed that PCB126 exposure resulted in a decrease in expression levels of Sirt1, factors related to mitochondrial fusion (Opa1, Mfn1, and Mfn2), antioxidant (CAT, SOD1, and SOD2), energy metabolism (PKM2, IDH, and SDH) and anti-apoptosis (Bcl-2), and an increase in expression levels of Nrf2 acetylation, mitochondrial fission (Drp1), factors that promote apoptosis (Cytc, Bax, Cas9, and Cas3) in L8824 cells. Furthermore, our findings revealed a decrease in ΔΨm, ATP concentration and ATPnase activity and apoptosis levels in L8824 cells. Noteworthy, treatment with Astilbin reversed these results. Molecular docking provides solid evidence for the interaction between Astilbin and Sirt1. In summary, our findings suggested that Astilbin promoted the deacetylation of Nrf2 by interacting with Sirt1, thereby alleviating PCB126-induced mitochondrial apoptosis mediated by mitochondrial dynamics imbalance and energy metabolism disorder through the inhibition of oxidative stress in L8824 cells. Our research has initially revealed the correlation between acetylation and apoptosis induced by PCB126, which provided a foundation for a better comprehension of PCB126 toxicity. Additionally, it expanded the potential application value of Astilbin.

Doxorubicin and other anthracyclines in cancers: Activity, chemoresistance and its overcoming

Anthracyclines have been important and effective treatments against a number of cancers since their discovery. However, their use in therapy has been complicated by severe side effects and toxicity that occur during or after treatment, including cardiotoxicity. The mode of action of anthracyclines is complex, with several mechanisms proposed. It is possible that their high toxicity is due to the large set of processes involved in anthracycline action. The development of resistance is a major barrier to successful treatment when using anthracyclines. This resistance is based on a series of mechanisms that have been studied and addressed in recent years. This work provides an overview of the anthracyclines used in cancer therapy. It discusses their mechanisms of activity, toxicity, and chemoresistance, as well as the approaches used to improve their activity, decrease their toxicity, and overcome resistance.

Lactate Improves Long-term Cognitive Impairment Induced By Repeated Neonatal Sevoflurane Exposures Through SIRT1-mediated Regulation of Adult Hippocampal Neurogenesis and Synaptic Plasticity in Male Mice

Repeated neonatal exposures to sevoflurane induce long-term cognitive impairment that has been reported to have sex-dependent differences. Exercise promotes learning and memory by releasing lactate from the muscle. The study tested the hypothesis that lactate may improve long-term cognitive impairment induced by repeated neonatal exposures to sevoflurane through SIRT1-mediated regulation of adult hippocampal neurogenesis and synaptic plasticity. C57BL/6 mice of both genders were exposed to 3% sevoflurane for 2 h daily from postnatal day 6 (P6) to P8. In the intervention experiments, mice received lactate at 1 g/kg intraperitoneally once daily from P21 to P41. Behavioral tests including open field (OF), object location (OL), novel object recognition (NOR), and fear conditioning (FC) tests were performed to assess cognitive function. The number of 5-Bromo-2'- deoxyuridine positive (BrdU+) cells and BrdU+/DCX+ (doublecortin) co-labeled cells, expressions of brain-derived neurotrophic factor (BDNF), activity-regulated cytoskeletal-associated protein (Arc), early growth response 1 (Egr-1), SIRT1, PGC-1α and FNDC5, and long-term potentiation (LTP) were evaluated in the hippocampus. Repeated exposures to sevoflurane induced deficits in OL, NOR and contextual FC tests in male but not female mice. Similarly, adult hippocampal neurogenesis, synaptic plasticity-related proteins and hippocampal LTP were impaired after repeated exposures to sevoflurane in male but not female mice, which could rescue by lactate treatment. Our study suggests that repeated neonatal exposures to sevoflurane inhibit adult hippocampal neurogenesis and induce defects of synaptic plasticity in male but not female mice, which may contribute to long-term cognitive impairment. Lactate treatment rescues these abnormalities through activation of SIRT1.

SIRT1 regulates osteoblast senescence through SOD2 acetylation and mitochondrial dysfunction in the progression of Osteoporosis caused by Cadmium exposure

Environmental Cadmium (Cd) is a toxicant with widespread exposure, documented adverse effects on bone homeostasis, and makes the onset of osteoporosis (OP), one of the age-related chronic diseases an enormous burden to modern societies worldwide. Aging is the largest risk factor for a multitude of age-related diseases and osteoblasts senescence reduces bone formation and is a key factor for osteoporosis. Despite anti-aging molecules the nuclear silent information regulator of transcription 1 (SIRT1) actions in chondrocytes and bone cells are critical for normal skeletal development and homeostasis, much less is known about the role of SIRT1 in osteoporosis. Here, we aim to demonstrate that SIRT1 mediates osteoblasts' senescence response to OP caused by Cd. The senescent osteoblasts accumulation and their viability were analyzed after Cd exposure. To explore the effects and mechanism of SIRT1 in Cd-induced osteoblastic senescence, we generated SIRT1-overexpressed osteoblast and SIRT1 conditional overexpression in the rat femur. Meanwhile, the OP rat model was established by removing bilateral ovaries. We found decreased SIRT1 expression and senescent osteoblasts accumulation after Cd exposure. Meanwhile, Cd exposure increased P53, P16INK4a, and P21CIPI proteins level, triggered DNA damage response (DDR) through the phosphorylation of ATM and H2AX, and caused mitochondrial dysfunction by the increased acetylation of SOD2 and excessive mitophagy. SIRT1 overexpression attenuated DDR and mitochondrial dysfunction and downregulated the increase of hall makers senescence caused by Cd in osteoblasts. We found overexpression of osteoblastic SIRT1 protects against Cd-induced senescence, which is likely driven by ATM-mediated DDR and SOD2ace-mediated mitochondrial dysfunction. Our study demonstrates the mechanism of SIRT1 in mediating bone homeostasis via senescence. Further mechanistic studies using specific SIRT1 mutations elucidating how SIRT1 modulates bone cell senescence, will provide new therapeutic strategies for human osteoporosis.

FIT links c-Myc and P53 acetylation by recruiting RBBP7 during colorectal carcinogenesis

Colorectal cancer (CRC) poses one of the most serious threats to human health worldwide, and abnormally expressed c-Myc and p53 are deemed the pivotal driving forces of CRC progression. In this study, we discovered that the lncRNA FIT, which was downregulated in CRC clinical samples, was transcriptionally suppressed by c-Myc in vitro and promoted CRC cell apoptosis by inducing FAS expression. FAS is a p53 target gene, and we found that FIT formed a trimer with RBBP7 and p53 that facilitated p53 acetylation and p53-mediated FAS gene transcription. Moreover, FIT was capable of retarding CRC growth in a mouse xenograft model, and FIT expression was positively correlated with FAS expression in clinical samples. Thus, our study elucidates the role of the lncRNA FIT in human colorectal cancer growth and provides a potential target for anti-CRC drugs.

Sirtuins: Promising Therapeutic Targets to Treat Ischemic Stroke

Stroke is a major cause of mortality and disability globally, with ischemic stroke (IS) accounting for over 80% of all stroke cases. The pathological process of IS involves numerous signal molecules, among which are the highly conserved nicotinamide adenine dinucleotide (NAD+)-dependent enzymes known as sirtuins (SIRTs). SIRTs modulate various biological processes, including cell differentiation, energy metabolism, DNA repair, inflammation, and oxidative stress. Importantly, several studies have reported a correlation between SIRTs and IS. This review introduces the general aspects of SIRTs, including their distribution, subcellular location, enzyme activity, and substrate. We also discuss their regulatory roles and potential mechanisms in IS. Finally, we describe the current therapeutic methods based on SIRTs, such as pharmacotherapy, non-pharmacological therapeutic/rehabilitative interventions, epigenetic regulators, potential molecules, and stem cell-derived exosome therapy. The data collected in this study will potentially contribute to both clinical and fundamental research on SIRTs, geared towards developing effective therapeutic candidates for future treatment of IS.

The SIRT1-c-Myc axis in regulation of stem cells

SIRT1 is the most conserved mammalian NAD+-dependent protein deacetylase. Through deacetylation of transcriptional factors and co-factors, this protein modification enzyme is critically involved in metabolic and epigenetic regulation of stem cells, which is functionally important in maintaining their pluripotency and regulating their differentiation. C-Myc, a key member of Myc proton-oncogene family, is a pivotal factor for transcriptional regulation of genes that control acquisition and maintenance of stemness. Previous cancer research has revealed an intriguing positive feedback loop between SIRT1 and c-Myc that is crucial in tumorigenesis. Recent literature has uncovered important functions of this axis in regulation of maintenance and differentiation of stem cells, including pluripotent stem cells and cancer stem cells. This review highlights recent advances of the SIRT1-c-Myc axis in stem cells.

Experimental Insights into the Interplay between Histone Modifiers and p53 in Regulating Gene Expression

Chromatin structure plays a fundamental role in regulating gene expression, with histone modifiers shaping the structure of chromatin by adding or removing chemical changes to histone proteins. The p53 transcription factor controls gene expression, binds target genes, and regulates their activity. While p53 has been extensively studied in cancer research, specifically in relation to fundamental cellular processes, including gene transcription, apoptosis, and cell cycle progression, its association with histone modifiers has received limited attention. This review explores the interplay between histone modifiers and p53 in regulating gene expression. We discuss how histone modifications can influence how p53 binds to target genes and how this interplay can be disrupted in cancer cells. This review provides insights into the complex mechanisms underlying gene regulation and their implications for potential cancer therapy.

Recent advancement of HDAC inhibitors against breast cancer

Recent studies highlight the great potential impact of HDAC inhibitors (HDACis) in suppressing TNBC, even though clinical trials including a single HDACis demonstrated unsatisfactory outcomes against TNBC. New compounds created to achieve isoform selectivity and/or a polypharmacological HDAC strategy have also produced interesting results. The current study discusses the HDACis pharmacophoric models and the structural alterations that produced drugs with strong inhibitory effects on TNBC progression. With more than 2 million new cases reported in 2018, breast cancer-the most common cancer among women worldwide-poses a significant financial burden on an already deteriorating public health system. Due to a lack of therapies being developed for triple-negative breast cancers and the development of resistance to the current treatment options, it is imperative to plan novel therapeutics in order to bring new medications to the pipeline. Additionally, HDACs deacetylate a large number of nonhistone cellular substrates that control a variety of biological processes, such as the beginning and development of cancer. The significance of HDACs in cancer and the therapeutic potential of HDAC inhibitor. Furthermore, we also reported molecular docking study with four HDAC inhibitors and performed molecular dynamic stimulation of the best dock score compound. Among the four ligands belinostat compound showed best binding affinity with histone deacetylase protein which was -8.7 kJ/mol. It also formed five conventional hydrogen bond with Gly 841, His 669, His 670, pro 809, and His 709 amino acid residues.

NAD+ Metabolism and Immune Regulation: New Approaches to Inflammatory Bowel Disease Therapies

Inflammatory bowel disease (IBD), which includes Crohn's disease (CD) and ulcerative colitis (UC), is a multifactorial systemic inflammatory immune response. Nicotinamide adenine dinucleotide (NAD⁺) is a co-enzyme involved in cell signaling and energy metabolism. Calcium homeostasis, gene transcription, DNA repair, and cell communication involve NAD⁺ and its degradation products. There is a growing recognition of the intricate relationship between inflammatory diseases and NAD⁺ metabolism. In the case of IBD, the maintenance of intestinal homeostasis relies on a delicate balance between NAD⁺ biosynthesis and consumption. Consequently, therapeutics designed to target the NAD⁺ pathway are promising for the management of IBD. This review discusses the metabolic and immunoregulatory processes of NAD⁺ in IBD to examine the molecular biology and pathophysiology of the immune regulation of IBD and to provide evidence and theoretical support for the clinical use of NAD⁺ in IBD.

Proteomic analysis reveals microvesicles containing NAMPT as mediators of radioresistance in glioma

Tumor-initiating cells contained within the aggressive brain tumor glioma (glioma stem cells, GSCs) promote radioresistance and disease recurrence. However, mechanisms of resistance are not well understood. Herein, we show that the proteome-level regulation occurring upon radiation treatment of several patient-derived GSC lines predicts their resistance status, whereas glioma transcriptional subtypes do not. We identify a mechanism of radioresistance mediated by the transfer of the metabolic enzyme NAMPT to radiosensitive cells through microvesicles (NAMPT-high MVs) shed by resistant GSCs. NAMPT-high MVs rescue the proliferation of radiosensitive GSCs and fibroblasts upon irradiation, and upon treatment with a radiomimetic drug or low serum, and increase intracellular NAD(H) levels. Finally, we show that the presence of NAMPT within the MVs and its enzymatic activity in recipient cells are necessary to mediate these effects. Collectively, we demonstrate that the proteome of GSCs provides unique information as it predicts the ability of glioma to resist radiation treatment. Furthermore, we establish NAMPT transfer via MVs as a mechanism for rescuing the proliferation of radiosensitive cells upon irradiation.

T-2 toxin and deoxynivalenol (DON) exert distinct effects on stress granule formation depending on altered activity of SIRT1

The T-2 toxin and deoxynivalenol (DON), as the most concerned members of trichothecenes, induce cellular stress responses and various toxic effects. Stress granules (SGs) are rapidly formed in response to stress and play an important role in the cellular stress response. However, it is not known whether T-2 toxin and DON induce SG formation. In this study, we found that T-2 toxin induces SG formation, while DON surprisingly suppresses SG formation. Meanwhile, we discovered that SIRT1 co-localized with SGs and regulated SG formation by controlling the acetylation level of the SG nucleator G3BP1. Upon T-2 toxin, the acetylation level of G3BP1 increased, but the opposite change was observed upon DON. Importantly, T-2 toxin and DON affect the activity of SIRT1 via changing NAD⁺ level in a different manner, though the mechanism remains to be clarified. These findings suggest that the distinct effects of T-2 toxin and DON on SG formation are caused by changes in the activity of SIRT1. Furthermore, we found that SGs increase the cell toxicity of T-2 toxin and DON. In conclusion, our results reveal the molecular regulation mechanism of TRIs on SG formation and provide novel insights into the toxicological mechanisms of TRIs.

Tong Sai granules improves AECOPD via regulation of MAPK-SIRT1-NF-κB pathway and cellular senescence alleviation

ETHNOPHARMACOLOGICAL RELEVANCE

Tong Sai granules (TSG) a traditional Chinese medicine, are used to treat acute exacerbations of chronic obstructive pulmonary disease (AECOPD). Cellular senescence is considered the mechanism underlying AECOPD progression.

AIM OF THE STUDY

This study aimed to investigate the therapeutic mechanisms of TSG in an AECOPD rat model (established using cigarette smoke exposure and bacterial infection) and focused on the inhibition of cellular senescence in vivo and in vitro.

MATERIALS AND METHODS

Histological changes and levels of inflammatory cytokines, matrix metalloproteinases (MMPs), p53, and p21 were determined. A cellular senescence model was established by challenging airway epithelial cells with cigarette smoke extract (CSE) and lipopolysaccharide (LPS). Quantitative PCR, western blotting, and immunofluorescence were used to measure mRNA and protein levels. Additionally, UPLC-Q-Extractive-Orbitrap MS analysis, network analysis, and transcriptomics were used to analyze the potential compounds and molecular mechanisms of TSG.

RESULTS

The results showed that oral administration of TSG significantly reduced the severity of AECOPD in rats by ameliorating lung function decline and pathological injuries and increasing the levels of C-reactive protein and serum amyloid A, two well-known proinflammatory mediators of the acute phase response. Oral TSG administration also decreased the expression levels of proinflammatory cytokines (e.g., IL-6, IL-1β, and TNF-α), MMPs (e.g., MMP-2 and MMP-9), critical regulators of senescence such as p21 and p53, and the apoptotic marker γH2AX, all of which are factors in cellular senescence in lung tissue. TSG4 was isolated from TSGs using macroporous resin and found to significantly suppress cellular senescence in CSE/LPS-induced bronchial epithelial cells. Furthermore, 26 of 56 compounds identified in TSG4 were used to predict 882 potential targets. Additionally, 317 differentially expressed genes (DEGs) were detected in CSE/LPS-treated bronchial epithelial cells. Network analysis of the 882 targets and 317 DEGs revealed that TSG4 regulated multiple pathways, among which the mitogen-activated protein kinase-sirtuin 1-nuclear factor kappa B (MAPK-SIRT1-NF-κB) pathway is important in terms of antisenescent mechanisms. Moreover, in CSE/LPS-induced bronchial epithelial cells, p-p38, p-ERK1/2, p-JNK, and p-p65 levels were increased and SIRT1 levels were decreased after TSG4 treatment. Additionally, oral TSG administration decreased p-p38 and p-p65 levels and increased SIRT1 levels in the lung tissues of AECOPD model rats.

CONCLUSION

Collectively, these results indicate that TSGs ameliorate AECOPD by regulating the MAPK-SIRT1-NF-κB signaling pathway and subsequently suppressing cellular senescence.

Metabolites as signalling molecules

Traditional views of cellular metabolism imply that it is passively adapted to meet the demands of the cell. It is becoming increasingly clear, however, that metabolites do more than simply supply the substrates for biological processes; they also provide critical signals, either through effects on metabolic pathways or via modulation of other regulatory proteins. Recent investigation has also uncovered novel roles for several metabolites that expand their signalling influence to processes outside metabolism, including nutrient sensing and storage, embryonic development, cell survival and differentiation, and immune activation and cytokine secretion. Together, these studies suggest that, in contrast to the prevailing notion, the biochemistry of a cell is frequently governed by its underlying metabolism rather than vice versa. This important shift in perspective places common metabolites as key regulators of cell phenotype and behaviour. Yet the signalling metabolites, and the cognate targets and transducers through which they signal, are only beginning to be uncovered. In this Review, we discuss the emerging links between metabolism and cellular behaviour. We hope this will inspire further dissection of the mechanisms through which metabolic pathways and intermediates modulate cell function and will suggest possible drug targets for diseases linked to metabolic deregulation.

The Role of NAD+, SIRTs Interactions in Stimulating and Counteracting Carcinogenesis

The World Health Organization has identified oncological diseases as one of the most serious health concerns of the current century. Current research on oncogenesis is focused on the molecular mechanisms of energy-biochemical reprogramming in cancer cell metabolism, including processes contributing to the Warburg effect and the pro-oncogenic and anti-oncogenic roles of sirtuins (SIRTs) and poly-(ADP-ribose) polymerases (PARPs). However, a clear understanding of the interaction between NAD⁺, SIRTs in cancer development, as well as their effects on carcinogenesis, has not been established, and literature data vary greatly. This work aims to provide a summary and structure of the available information on NAD⁺, SIRTs interactions in both stimulating and countering carcinogenesis, and to discuss potential approaches for pharmacological modulation of these interactions to achieve an anticancer effect.

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.

A pharmacological review on SIRT 1 and SIRT 2 proteins, activators, and inhibitors: Call for further research

Sirtuins or Sir (Silent information regulator) are NAD⁺-dependent enzymes playing an important part in the pathogenesis and treatment of various disorders. They have ubiquitously expressed protein deacetylases. They are implicated in several cellular activities like DNA repair, cellular metabolism, mitochondrial function, and inflammation. Deletion of sirtuin protein, SIRT1 in the organs like brain, heart, liver and pancreas can cause inflammation and increases the level of free radical ions causing oxidative stress. Inflammation and oxidative stress are closely associated with pathophysiological events in many chronic diseases, like diabetes, cancer, cardiovascular, osteoporosis, and neurodegenerative diseases. Modulation of SIRT1 gene expression might help in preventing the progression of chronic diseases related to the brain, heart, liver, and pancreas. SIRT2 proteins play an essential role in tumorigenesis, including tumor-suppressing and tumor-promoting functions. Sirtuin activators are molecules that upregulate the activity of Sirtuins in the body. Their multifaceted uses have surprised the global scientific community. They are found to control obesity, lower cardiac risks, battle cancer, etc. This article provides an update on the pharmacological effect of SIRT1 and SIRT 2 proteins, their activators and inhibitors, and their molecular mechanism. It provides novel insights for future research in targeted therapy and drug development.

Adenosine A2A receptor activation reduces chondrocyte senescence

Osteoarthritis (OA) pathogenesis is associated with reduced chondrocyte homeostasis and increased levels of cartilage cellular senescence. Chondrosenescence is the development of cartilage senescence that increases with aging joints and disrupts chondrocyte homeostasis and is associated with OA. Adenosine A2A receptor (A2AR) activation in cartilage via intra-articular injection of liposomal A2AR agonist, liposomal-CGS21680, leads to cartilage regeneration in vivo and chondrocyte homeostasis. A2AR knockout mice develop early OA isolated chondrocytes demonstrate upregulated expression of cellular senescence and aging-associated genes. Based on these observations, we hypothesized that A2AR activation would ameliorate cartilage senescence. We found that A2AR stimulation of chondrocytes reduced beta-galactosidase staining and regulated levels and cell localization of common senescence mediators p21 and p16 in vitro in the human TC28a2 chondrocyte cell line. In vivo analysis similarly showed A2AR activation reduced nuclear p21 and p16 in obesity-induced OA mice injected with liposomal-CGS21680 and increased nuclear p21 and p16 in A2AR knockout mouse chondrocytes compared to wild-type mice. A2AR agonism also increased activity of the chondrocyte Sirt1/AMPK energy-sensing pathway by enhancing nuclear Sirt1 localization and upregulating T172-phosphorylated (active) AMPK protein levels. Lastly, A2AR activation in TC28a2 and primary human chondrocytes reduced wild-type p53 and concomitantly increased p53 alternative splicing leading to increase in an anti-senescent p53 variant, Δ133p53α. The results reported here indicate that A2AR signaling promotes chondrocyte homeostasis in vitro and reduces OA cartilage development in vivo by reducing chondrocyte senescence.

Specific regulation of BACH1 by the hotspot mutant p53R175H reveals a distinct gain-of-function mechanism

Although the gain of function (GOF) of p53 mutants is well recognized, it remains unclear whether different p53 mutants share the same cofactors to induce GOFs. In a proteomic screen, we identified BACH1 as a cellular factor that recognizes the p53 DNA-binding domain depending on its mutation status. BACH1 strongly interacts with p53R175H but fails to effectively bind wild-type p53 or other hotspot mutants in vivo for functional regulation. Notably, p53R175H acts as a repressor for ferroptosis by abrogating BACH1-mediated downregulation of SLC7A11 to enhance tumor growth; conversely, p53R175H promotes BACH1-dependent tumor metastasis by upregulating expression of pro-metastatic targets. Mechanistically, p53R175H-mediated bidirectional regulation of BACH1 function is dependent on its ability to recruit the histone demethylase LSD2 to target promoters and differentially modulate transcription. These data demonstrate that BACH1 acts as a unique partner for p53R175H in executing its specific GOFs and suggest that different p53 mutants induce their GOFs through distinct mechanisms.

RNA methylation and cellular response to oxidative stress-promoting anticancer agents

Disruption of the complex network that regulates redox homeostasis often underlies resistant phenotypes, which hinder effective and long-lasting cancer eradication. In addition, the RNA methylome-dependent control of gene expression also critically affects traits of cellular resistance to anti-cancer agents. However, few investigations aimed at establishing whether the epitranscriptome-directed adaptations underlying acquired and/or innate resistance traits in cancer could be implemented through the involvement of redox-dependent or -responsive signaling pathways. This is unexpected mainly because: i) the effectiveness of many anti-cancer approaches relies on their capacity to promote oxidative stress (OS); ii) altered redox milieu and reprogramming of mitochondrial function have been acknowledged as critical mediators of the RNA methylome-mediated response to OS. Here we summarize the current state of understanding on this topic, as well as we offer new perspectives that might lead to original approaches and strategies to delay or prevent the problem of refractory cancer and tumor recurrence.

DNA damage response signaling: A common link between cancer and cardiovascular diseases

DNA damage response (DDR) signaling ensures genomic and proteomic homeostasis to maintain a healthy genome. Dysregulation either in the form of down- or upregulation in the DDR pathways correlates with various pathophysiological states, including cancer and cardiovascular diseases (CVDs). Impaired DDR is studied as a signature mechanism for cancer; however, it also plays a role in ischemia-reperfusion injury (IRI), inflammation, cardiovascular function, and aging, demonstrating a complex and intriguing relationship between cancer and pathophysiology of CVDs. Accordingly, there are increasing number of reports indicating higher incidences of CVDs in cancer patients. In the present review, we thoroughly discuss (1) different DDR pathways, (2) the functional cross talk among different DDR mechanisms, (3) the role of DDR in cancer, (4) the commonalities and differences of DDR between cancer and CVDs, (5) the role of DDR in pathophysiology of CVDs, (6) interventional strategies for targeting genomic instability in CVDs, and (7) future perspective.

Evaluation of Sirtuin1 Overexpression by Immunohistochemistry in Cervical Intraepithelial Lesions and Invasive Squamous Cell Carcinoma

Cervical cancer is one of the most common genital cancers in the woman with approximately half a million new cases per year. Development of invasive squamous cell carcinoma (SCC) is the result of persistent and frequent human papilloma virus infection in premalignant lesions of cervix. Thereby identification of biomarkers that could predict progression of dysplastic mucosa to invasive cancer is of great clinical significance. Overexpression of SIRT1 has been reported to induce tumorogenesis in several organs. We evaluated SIRT1 expression in normal squamous epithelium of cervix, low-grade and high-grade cervical intraepithelial lesions and invasive SCC. A total of 104 cases were selected including 34 low-grade cervical intraepithelial lesions (CINs), 37 high-grade CINs, and 35 cases of invasive SCC. The normal cervical epithelium showed negative or weak SIRT1 positivity only in basal layers. SIRT1 cytoplasmic expression was found in 13 of 34 (38.2%) of low-grade CINs, 31 of 37 (83.8%) of high-grade CINs and all 35 (100%) cases of invasive SCC. Expression between 2 groups of CIN was statistically significant ( P =0.001). Thus, SIRT1 appears to be a promising biomarker for predicting the progression of CIN to invasive SCC.

Microplitis bicoloratus parasitism promotes cyclophilin D-p53 interaction to induce apoptosis of hemocytes in Spodoptera litura

Microplitis bicoloratus parasitism can induce apoptosis of hemocytes in the M. bicolortus host, Spodoptera litura. However, it is unclear how M. bicolortus parasitism regulates host signaling pathways to induce apoptosis. Expression of cyclophilin D (CypD) and p53 was significantly upregulated in S. litura hemocytes at 6 days postparasitization. In the parasitized hemocytes, there was mitochondrial membrane potential (△Ψ_m ) loss, cytochrome c (Cyt C) release from mitochondria, and caspase-3 activation. These occurred while hemocytes were undergoing upregulation of CypD and p53. Parasitism also promoted the interaction between CypD and p53. CypD silencing could rescue the apoptotic phenotypes induced by parasitism, but had no effect on apoptosis in unparasitized S. litura. These findings suggest that the CypD-p53 pathway may be an important component of the parasitism-induced immunosuppressive response and establish a basis for further studies of parasitoid/host interactions.

Alteration in branching morphogenesis via YAP/TAZ in fibroblasts of fetal lungs in an LPS-induced inflammation model

BACKGROUND

Chorioamnionitis is a common cause of preterm birth and leads to serious complications in newborns. The objective of this study was to investigate the role of the Hippo signaling pathway in lung branching morphogenesis under a lipopolysaccharide (LPS)-induced inflammation model.

MATERIALS AND METHODS

IMR-90 cells and ex vivo fetal lungs were treated with 0, 10, 30, or 50 μg/ml LPS for 24 and 72 h. Supernatant levels of lactate dehydrogenase (LDH), interleukin (IL)-6, IL-8, Chemokine (C-X-C motif) ligand 1(CXCL1), branching and the surface area ratio, Yes-associated protein (YAP), transcription coactivator with PDZ-binding motif (TAZ), fibroblast growth factor 10 (FGF10), fibroblast growth factor receptor II (FGFR2), SRY-box transcription factor 2 (SOX2), SOX9, and sirtuin 1 (SIRT1) levels were examined. Differentially expressed genes in fetal lungs after LPS treatment were identified by RNA-sequencing.

RESULTS

LPS at 50 μg/ml increased IL-6 and IL-8 in IMR-90 cells and increased IL-6, CXCL1 and LDH in fetal lungs. The branching ratio significantly increased by LPS at 30 μg/ml compared to the control but the increased level had decreased by 50 μg/ml LPS exposure. Exposure to 50 μg/ml LPS increased phosphorylated (p)-YAP, p-YAP/YAP, and p-TAZ/TAZ in IMR-90 cells, whereas 50 μg/ml LPS decreased FGF10 and SOX2. Consistently, p-YAP/YAP and p-TAZ/TAZ were increased in fibronectin⁺ cells of fetal lungs. Moreover, results of RNA-sequencing in fetal lungs showed that SMAD, FGF, IκB phosphorylation, tissue remodeling and homeostasis was involved in branching morphogenesis following exposure to 50 μg/ml LPS. The p-SIRT1/SIRT1 ratio increased in IMR-90 cells by LPS treatment.

CONCLUSIONS

This study showed that regulation of the Hippo pathway in fibroblasts of fetal lungs was involved in branching morphogenesis under an inflammatory disease such as chorioamnionitis.

Cocoa Polyphenol Extract Inhibits Cellular Senescence via Modulation of SIRT1 and SIRT3 in Auditory Cells

Cocoa, rich in polyphenols, has been reported to provide many health benefits due to its antioxidant properties. In this study, we investigated the effect of Cocoa polyphenols extract (CPE) against oxidative stress-induced cellular senescence using a hydrogen peroxide (H₂O₂)-induced cellular senescence model in three auditory cells lines derived from the auditory organ of a transgenic mouse: House Ear Institute-Organ of Corti 1 (HEI-OC1), Organ of Corti-3 (OC-k3), and Stria Vascularis (SV-k1) cells. Our results showed that CPE attenuated senescent phenotypes, including senescence-associated β-galactosidase expression, cell proliferation, alterations of morphology, oxidative DNA damage, mitochondrial dysfunction by inhibiting mitochondrial reactive oxygen species (mtROS) generation, and related molecules expressions such as forkhead box O3 (FOXO3) and p53. In addition, we determined that CPE induces expression of sirtuin 1 (SIRT1) and sirtuin 3 (SIRT3), and it has a protective role against cellular senescence by upregulation of SIRT1 and SIRT3. These data indicate that CPE protects against senescence through SIRT1, SIRT3, FOXO3, and p53 in auditory cells. In conclusion, these results suggest that Cocoa has therapeutic potential against age-related hearing loss (ARHL).

SIRT1 in the cardiomyocyte counteracts doxorubicin-induced cardiotoxicity via regulating histone H2AX

AIMS

Cardiotoxicity by doxorubicin predicts worse prognosis of patients. Accumulation of damaged DNA has been implicated in doxorubicin-induced cardiotoxicity. SIRT1, an NAD+-dependent histone/protein deacetylase, protects cells by deacetylating target proteins. We investigated whether SIRT1 counteracts doxorubicin-induced cardiotoxicity by mediating Ser139 phosphorylation of histone H2AX, a critical signal of the DNA damage response.

METHODS AND RESULTS

Doxorubicin (5 mg/kg per week, x4) was administered to mice with intact SIRT1 (Sirt1f/f) and mice that lack SIRT1 activity in cardiomyocytes (Sirt1f/f;MHCcre/+). Reductions in left ventricular fractional shortening and ejection fraction by doxorubicin treatment were more severe in Sirt1f/f;MHCcre/+ than in Sirt1f/f. Myocardial expression level of type-B natriuretic peptide was 2.5-fold higher in Sirt1f/f;MHCcre/+ than in Sirt1f/f after doxorubicin treatment. Sirt1f/f;MHCcre/+ showed larger fibrotic areas and higher nitrotyrosine levels in the heart after doxorubicin treatment. Although doxorubicin-induced DNA damage evaluated by TUNEL staining was enhanced in Sirt1f/f;MHCcre/+, the myocardium from Sirt1f/f;MHCcre/+ showed blunted Ser139 phosphorylation of H2AX by doxorubicin treatment. In H9c2 cardiomyocytes, SIRT1 knockdown attenuated Ser139 phosphorylation of H2AX, increased DNA damage, and enhanced caspase-3 activation under doxorubicin treatment. Immunostaining revealed that acetylation level of H2AX at Lys5 was higher in hearts from Sirt1f/f;MHCcre/+. In H9c2 cells, acetyl-Lys5-H2AX level was increased by SIRT1 knockdown and reduced by SIRT1 overexpression. Ser139 phosphorylation in response to doxorubicin treatment was blunted in a mutant H2AX with substitution of Lys5 to Gln (K5Q) that mimics acetylated lysine compared with that in wild-type H2AX. Expression of K5Q-H2AX as well as S139A-H2AX, which cannot be phosphorylated at Ser139, augmented doxorubicin-induced caspase-3 activation. Treatment of mice with resveratrol, a SIRT1 activator, attenuated doxorubicin-induced cardiac dysfunction, which was associated with a reduction in acetyl-Lys5-H2AX level and a preserved phospho-Ser139-H2AX level.

CONCLUSION

These findings suggest that SIRT1 counteracts doxorubicin-induced cardiotoxicity by mediating H2AX phosphorylation through its deacetylation in cardiomyocytes.

MiRNA Differences Related to Treatment-Resistant Schizophrenia

Schizophrenia (SZ) is a serious mental disorder that is typically treated with antipsychotic medication. Treatment-resistant schizophrenia (TRS) is the condition where symptoms remain after pharmacological intervention, resulting in long-lasting functional and social impairments. As the identification and treatment of a TRS patient requires previous failed treatments, early mechanisms of detection are needed in order to quicken the access to effective therapy, as well as improve treatment adherence. In this study, we aim to find a microRNA (miRNA) signature for TRS, as well as to shed some light on the molecular pathways potentially involved in this severe condition. To do this, we compared the blood miRNAs of schizophrenia patients that respond to medication and TRS patients, thus obtaining a 16-miRNA TRS profile. Then, we assessed the ability of this signature to separate responders and TRS patients using hierarchical clustering, observing that most of them are grouped correctly (~70% accuracy). We also conducted a network, pathway analysis, and bibliography search to spot molecular pathways potentially altered in TRS. We found that the response to stress seems to be a key factor in TRS and that proteins p53, SIRT1, MDM2, and TRIM28 could be the potential mediators of such responses. Finally, we suggest a molecular pathway potentially regulated by the miRNAs of the TRS profile.

Atractylodes lancea and Magnolia officinalis combination protects against high fructose-impaired insulin signaling in glomerular podocytes through upregulating Sirt1 to inhibit p53-driven miR-221

ETHNOPHARMACOLOGICAL RELEVANCE

In traditional Chinese medicine, a long term of improper diet causes the Dampness and disturbs Zang-Fu's functions including Kidney deficiency. Atractylodes lancea (Atr) and Magnolia officinalis (Mag) as a famous herb pair are commonly used to transform Dampness, with kidney protection.

AIM OF THE STUDY

To explore how Atr and Mag protected against insulin signaling impairment in glomerular podocytes induced by high dietary fructose feeding, a major contributor for insulin resistance in glomerular podocyte dysfunction.

MATERIALS AND METHODS

Liquid chromatography-tandem mass spectrometry (LC-MS/MS) analyze constituents of Atr and Mag. Rat model was induced by 10% fructose drinking water in vivo, and heat-sensitive human podocyte cells (HPCs) were exposed to 5 mM fructose in vitro. Animal or cultured podocyte models were treated with different doses of Atr, Mag or Atr and Mag combination. Western blot, qRT-PCR and immunofluorescence assays as well as other experiments were performed to detect adiponectin receptor protein 1 (AdipoR1), protein kinase B (AKT), Sirt1, p53 and miR-221 levels in rat glomeruli or HPCs, respectively.

RESULTS

Fifty-five components were identified in Atr and Mag combination. Network pharmacology analysis indicated that Atr and Mag combination might affect insulin signaling pathway. This combination significantly improved systemic insulin resistance and prevented glomerulus morphological damage in high fructose-fed rats. Of note, high fructose decreased IRS1, AKT and AdipoR1 in rat glomeruli and cultured podocytes. Further data from cultured podocytes with Sirt1 inhibitor/agonist, p53 agonist/inhibitor, or miR-221 mimic/inhibitor showed that high fructose downregulated Sirt1 to stimulate p53-driven miR-221, resulting in insulin signaling impairment. Atr and Mag combination effectively increased Sirt1, and decreased p53 and miR-221 in in vivo and in vitro models.

CONCLUSIONS

Atr and Mag combination improved insulin signaling in high fructose-stimulated glomerular podocytes possibly through upregulating Sirt1 to inhibit p53-driven miR-221. Thus, the regulation of Sirt1/p53/miR-221 by this combination may be a potential therapeutic approach in podocyte insulin signaling impairment.

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.

Magnesium Supplementation Affects the Expression of Sirtuin1, Tumor Protein P53 and Endothelial Nitric Oxide Synthase Genes in Patients with Atherosclerosis: A Double-Blind, Randomized, Placebo-Controlled Trial

Magnesium seems to play a role in improving cardiovascular function, but its exact mechanism is unknown. In this study, we hypothesized that magnesium could modulate the expression of genes involved in atherosclerosis. The aim of the present investigation was to evaluate the effect of magnesium sulfate on the expression of sirtuin1 (SIRT1), tumor protein p53 (TP53), and endothelial nitric oxide synthase (eNOS) genes in patients with atherosclerosis. This study was a placebo-controlled double-blind randomized clinical trial on 56 patients with angiographically proven atherosclerosis. Participants were randomly divided into two groups receiving 300 mg/day magnesium sulfate (n = 29) and placebo (n = 27) for three months (following up every month). Fasting blood samples were taken before and after the intervention and total RNA was extracted and used to evaluate the expression level of SIRT1, TP53, and eNOS genes by Real-Time PCR. The expression of eNOS gene was significantly increased (P < 0.0001) and the expression of TP53 gene was decreased (P = 0.02) in the magnesium sulfate group compared to the placebo group. But SIRT1 gene expression was not significantly different between the two groups. Our findings demonstrate that magnesium sulfate supplementation may have a protective role against the progression of atherosclerosis through upregulation of eNOS and downregulation of TP53 gene. Trial registration: This present clinical trial has been registered in the Iranian Registry of Clinical Trials (IRCT) with the registration code of "IRCT20151028024756N3", https://www.irct.ir/trial/29097?revision=114102. Registered on 16 December 2019.

Comprehensive analysis of nicotinamide metabolism-related signature for predicting prognosis and immunotherapy response in breast cancer

Background

Breast cancer (BC) is the most common malignancy among women. Nicotinamide (NAM) metabolism regulates the development of multiple tumors. Herein, we sought to develop a NAM metabolism-related signature (NMRS) to make predictions of survival, tumor microenvironment (TME) and treatment efficacy in BC patients.

Methods

Transcriptional profiles and clinical data from The Cancer Genome Atlas (TCGA) were analyzed. NAM metabolism-related genes (NMRGs) were retrieved from the Molecular Signatures Database. Consensus clustering was performed on the NMRGs and the differentially expressed genes between different clusters were identified. Univariate Cox, Lasso, and multivariate Cox regression analyses were sequentially conducted to develop the NAM metabolism-related signature (NMRS), which was then validated in the International Cancer Genome Consortium (ICGC) database and Gene Expression Omnibus (GEO) single-cell RNA-seq data. Further studies, such as gene set enrichment analysis (GSEA), ESTIMATE, CIBERSORT, SubMap, and Immunophenoscore (IPS) algorithm, cancer-immunity cycle (CIC), tumor mutation burden (TMB), and drug sensitivity were performed to assess the TME and treatment response.

Results

We identified a 6-gene NMRS that was significantly associated with BC prognosis as an independent indicator. We performed risk stratification according to the NMRS and the low-risk group showed preferable clinical outcomes (P < 0.001). A comprehensive nomogram was developed and showed excellent predictive value for prognosis. GSEA demonstrated that the low-risk group was predominantly enriched in immune-associated pathways, whereas the high-risk group was enriched in cancer-related pathways. The ESTIMATE and CIBERSORT algorithms revealed that the low-risk group had a higher abundance of anti-tumor immunocyte infiltration (P < 0.05). Results of Submap, IPS, CIC, TMB, and external immunotherapy cohort (iMvigor210) analyses showed that the low-risk group were indicative of better immunotherapy response (P < 0.05).

Conclusions

The novel signature offers a promising way to evaluate the prognosis and treatment efficacy in BC patients, which may facilitate clinical practice and management.