A dual recognition-based strategy employing Ni-modified metal-organic framework for in situ screening of SIRT1 inhibitors from Chinese herbs.

Sirtuin1 (SIRT1), an NAD+-dependent histone deacetylase, plays a crucial role in regulating molecular signaling pathways. Recently, inhibition of SIRT1 rather than its activation shows the therapeutic potential for central nervous system disorder, however, the discovered SIRT1 inhibitors remains limited. In this work, a dual recognition-based strategy was developed to screen SIRT1 inhibitors from natural resources in situ. This approach utilized a Ni-modified metal-organic framework (Ni@Tyr@UiO-66-NH2) along with cell lysate containing an engineered His-tagged SIRT1 protein, eliminating the need for purified proteins, pure compounds, and protein immobilization. The high-performance Ni@Tyr@UiO-66-NH2 was synthesized by modifying the surface of UiO-66-NH2 with Ni2+ ions to specifically capture His-tagged SIRT1 while persevering its enzyme activity. By employing dual recognition, in which Ni@Tyr@UiO-66-NH2 recognized SIRT1 and SIRT1 recognized its ligands, the process of identifying SIRT1 inhibitors from complex matrix was vastly streamlined. The developed method allowed the efficient discovery of 16 natural SIRT1 inhibitors from Chinese herbs. Among them, 6 compounds were fully characterized, and suffruticosol A was found to have an excellent IC50 value of 0.95 ±â€¯0.12 µM. Overall, an innovative dual recognition-based strategy was proposed to efficiently identify SIRT1 inhibitors in this study, offering scientific clues for the development of drugs targeting CNS disorders.

SIRT1-Rab7 axis attenuates NLRP3 and STING activation through late endosomal-dependent mitophagy during sepsis-induced acute lung injury.

BACKGROUND: Acute lung injury (ALI) is a leading cause of mortality in patients with sepsis due to proinflammatory endothelial changes and endothelial permeability defects. Mitochondrial dysfunction is recognized as a critical mediator in the pathogenesis of sepsis-induced ALI. Although mitophagy regulation of mitochondrial quality is well recognized, little is known about its role in lung ECs during sepsis-induced ALI. Sirtuin 1 (SIRT1) is a histone protein deacetylase involved in inflammation, mitophagy, and cellular senescence. Here, the authors show a type of late endosome-dependent mitophagy that inhibits NLRP3 and STING activation through SIRT1 signaling during sepsis-induced ALI. METHODS: C57BL/6J male mice with or without administration of the SIRT1 inhibitor EX527 in the CLP model and lung ECs in vitro were developed to identify mitophagy mechanisms that underlie the cross-talk between SIRT1 signaling and sepsis-induced ALI. RESULTS: SIRT1 deficient mice exhibited exacerbated sepsis-induced ALI. Knockdown of SIRT1 interfered with mitophagy through late endosome Rab7, leading to the accumulation of damaged mitochondria and inducing excessive mitochondrial reactive oxygen species (mtROS) generation and cytosolic release of mitochondrial DNA (mtDNA), which triggered NLRP3 inflammasome and the cytosolic nucleotide sensing pathways (STING) over-activation. Pharmacological inhibition of STING and NLRP3 i n vivo or genetic knockdown in vitro reversed SIRT1 deficiency mediated endothelial permeability defects and endothelial inflammation in sepsis-induced ALI. Moreover, activation of SIRT1 with SRT1720 in vivo or overexpression of SIRT1 in vitro protected against sepsis-induced ALI. CONCLUSION: These findings suggest that SIRT1 signaling is essential for restricting STING and NLRP3 hyperactivation by promoting endosomal-mediated mitophagy in lung ECs, providing potential therapeutic targets for treating sepsis-induced ALI.

Virtual screening identifies tipranavir as a SIRT1 inhibitor with anti-hepatocarcinoma effect.

Aim: To identify novel inhibitors of SIRT1 and to understand their mechanism of action in hepatocellular carcinoma. Materials & methods: Molecular docking and dynamic simulations were conducted to identify potential SIRT1 inhibitors. The in vitro efficacy of the inhibitors was evaluated by methyl thiazolyl tetrazolium assays, flow cytometry and western blot analysis. Additionally, the in vivo antitumor activity of the inhibitor was evaluated. Results: Tipranavir, a US FDA-approved anti-HIV-1 medication, was found to possess potential as a SIRT1 inhibitor. Tipranavir selectively inhibited HepG2 cell proliferation without causing toxicity to normal human hepatic cells. Additionally, tipranavir treatment resulted in a reduction of SIRT1 expression and induction of apoptosis in HepG2 cells. Furthermore, tipranavir was found to suppress tumorigenesis in a xenograft mouse model and decreased the expression of SIRT1 in vivo. Conclusion: Tipranavir holds desirable potential as a promising therapeutic agent against hepatoma.

Sirtuin1 inhibitor attenuates hypertension in spontaneously hypertensive rats: role of Giα proteins and nitroxidative stress.

BACKGROUND: We recently showed that vascular smooth muscle cells (VSMCs) from spontaneously hypertensive rats (SHR) exhibit overexpression of Sirtuin1 (Sirt1) that contributes to the enhanced expression of Giα proteins implicated in the development of hypertension in SHR. METHOD: The present study investigated if the inhibition of Sirt1 could also ameliorate hypertension in SHR and explore the underlying molecular mechanisms. For this study, a selective inhibitor of Sirt1, EX-527 (5 mg/kg of body weight), was injected intraperitoneally into 8-week-old SHR and age-matched Wistar Kyoto (WKY) rats twice per week for 3 weeks. The blood pressure (BP) and heart rate was measured twice a week by the CODA noninvasive tail cuff method. RESULTS: The high BP and augmented heart rate in SHR was significantly attenuated by EX-527 treatment, which was associated with the suppression of the overexpression of Sirt1 and Giα proteins in heart, VSMC and aorta. In addition, the enhanced levels of superoxide anion, NADPH oxidase activity, overexpression of NADPH oxidase subunits and FOXO1 were attenuated and the decreased levels of endothelial nitric oxide synthase (eNOS), nitric oxide and increased levels of peroxynitrite (ONOO-) and tyrosine nitration in VSMC from SHR were restored to control levels by EX-527 treatment. Furthermore, knockdown of FOXO1 by siRNA also attenuated the overexpression of Giα-2 and NADPH oxidase subunit proteins and restored the decreased expression of eNOS in VSMC from SHR. CONCLUSION: These results suggest that the inhibition of overexpressed Sirt1 and its target FOXO1 through decreasing the enhanced levels of Giα proteins and nitro-oxidative stress attenuates the high BP in SHR.

Hypothyroidism confers tolerance to cerebral malaria.

The modulation of the host's metabolism to protect tissue from damage induces tolerance to infections increasing survival. Here, we examined the role of the thyroid hormones, key metabolic regulators, in the outcome of malaria. Hypothyroidism confers protection to experimental cerebral malaria by a disease tolerance mechanism. Hypothyroid mice display increased survival after infection with Plasmodium berghei ANKA, diminishing intracranial pressure and brain damage, without altering pathogen burden, blood-brain barrier disruption, or immune cell infiltration. This protection is reversed by treatment with a Sirtuin 1 inhibitor, while treatment of euthyroid mice with a Sirtuin 1 activator induces tolerance and reduces intracranial pressure and lethality. This indicates that thyroid hormones and Sirtuin 1 are previously unknown targets for cerebral malaria treatment, a major killer of children in endemic malaria areas.

Protective effects of a SIRT1 inhibitor on primordial follicle activation and growth induced by cyclophosphamide: insights from a bovine in vitro folliculogenesis system.

PURPOSE: Although oncological advances have improved survival rates of female cancer patients, they often suffer a reduced fertility due to treatment side effects. In the present study, we evaluated the potential fertoprotective effects of the specific inhibitor of SIRT1, EX-527, on the gonadotoxic action exerted by cyclophosphamide (CPM) on loss of primordial follicles (PFs). METHODS: The effects of the CPM metabolite phosphoramide mustard (PM) on follicle activation, growth and viability and the protective action of EX-527 against PM effects were evaluated on bovine ovarian cortical strips in vitro cultured for 1 or 6 days. To understand whether PFs exposed to PM plus EX-527 were able to activate and grow to the secondary stage after suspension of the treatment, strips cultured for 3 days in PM plus EX-527 for 3 days were transferred to plain medium until day 6. Follicle growth and health were evaluated through histology and viability assay at a confocal microscope. In order to investigate the molecular pathways underlying the ovarian response to PM in the presence of EX-527, we analysed the protein level of SIRT1, HuR, PARP1 and SOD2 after 1 day of in vitro culture. RESULTS: We found that (1) PM, the main CPM active metabolite, promotes PF activation; (2) the ovarian stress response induced by PM includes a SIRT1-dependent pathway; and (3) EX-527 reduces PF activation and growth induced by PM. CONCLUSION: SIRT1 can represent a candidate molecule to be targeted to protect ovarian follicles from alkylating agents and EX-527 could represent a potential fertoprotective agent for cancer patients.

Tetrahydroxy stilbene glycoside attenuates endothelial cell premature senescence induced by H2O2 through the microRNA-34a/SIRT1 pathway.

Numerous studies have demonstrated that endothelial cell senescence plays a decisive role in the development and progression of cardiovascular diseases (CVD). Our previous results confirmed that Tetrahydroxy stilbene glycoside (TSG) can alleviate the human umbilical vein endothelial cells (HUVECs) senescence induced by H2O2 through SIRT1. It has been reported that miR-34a is a translational suppressor of SIRT1. In this study, we aimed to explore whether TSG regulates SIRT1 through miR-34a to ameliorate HUVECs senescence. H2O2 was used to induce premature senescence in HUVECs, and miR-34a mimic or inhibitor were transfected to over-express or suppress the expression level of miR-34a. Results revealed that TSG apparently decreased the miR-34a expression level in H2O2-induced premature senescence of HUVECs. When SIRT1 expression was inhibited by EX527, the attenuation of TSG on the expression level of miR-34a were abolished. When miR-34a expression was knockdown, the effect of TSG on HUVECs senescence could be enhanced. While miR-34a mimic could reverse the effect of TSG on HUVECs senescence. In conclusion, we demonstrated that TSG could attenuated endothelial cell senescence by targeting miR-34a/SIRT1 pathway.

Role of SIRT1 and Progesterone Resistance in Normal and Abnormal Endometrium.

CONTEXT: Progesterone resistance, a known pathologic condition associated with a reduced cellular response to progesterone and heightened estrogen responses, appears to have a normal physiologic role in mammalian reproduction. The molecular mechanism responsible for progesterone resistance in normal and abnormal endometrium remains unclear. OBJECTIVE: To examine the roles of sirtuin-1 (SIRT1) in normal endometrium as well as endometrium associated with infertility and endometriosis, as an epigenetic modulator associated with progesterone resistance. METHODS: SIRT1 expression was examined by Western blot, quantitative real-time polymerase chain reaction, and immunohistochemistry in mouse uterus and human endometrium. Mice with uterine specific Sirt1 overexpression were developed to examine SIRT1's role in endometrial function and endometriosis development. EX-527, a SIRT1 inhibitor, and SRT1720, a SIRT1 agonist, were also used to evaluate SIRT1 effect on endometriosis. RESULTS: In normal healthy women, endometrial SIRT1 is expressed only during menses. SIRT1 was dramatically overexpressed in the endometrium from women with endometriosis in both the epithelium and stroma. In mice, SIRT1 is expressed at the time of implantation between day 4.5 and 5.5 of pregnancy. Overexpression of SIRT1 in the mouse uterus leads to subfertility due to implantation failure, decidualization defects and progesterone resistance. SIRT1 overexpression in endometriotic lesions promotes worsening endometriosis development. EX-527 significantly reduced the number of endometriotic lesions in the mouse endometriosis model. CONCLUSIONS: SIRT1 expression and progesterone resistance appears to play roles in normal endometrial functions. Aberrant SIRT1 expression contributes to progesterone resistance and may participate in the pathophysiology of endometriosis. SIRT1 is a novel and targetable protein for the diagnosis as well as treatment of endometriosis and the associated infertility seen in this disease.

SIRT1 Promotes M2 Microglia Polarization via Reducing ROS-Mediated NLRP3 Inflammasome Signaling After Subarachnoid Hemorrhage.

Mounting evidence has suggested that modulating microglia polarization from pro-inflammatory M1 phenotype to anti-inflammatory M2 state might be a potential therapeutic approach in the treatment of subarachnoid hemorrhage (SAH) injury. Our previous study has indicated that sirtuin 1 (SIRT1) could ameliorate early brain injury (EBI) in SAH by reducing oxidative damage and neuroinflammation. However, the effects of SIRT1 on microglial polarization and the underlying molecular mechanisms after SAH have not been fully illustrated. In the present study, we first observed that EX527, a potent selective SIRT1 inhibitor, enhanced microglial M1 polarization and nod-like receptor pyrin domain-containing 3 (NLRP3) inflammasome activation in microglia after SAH. Administration of SRT1720, an agonist of SIRT1, significantly enhanced SIRT1 expression, improved functional recovery, and ameliorated brain edema and neuronal death after SAH. Moreover, SRT1720 modulated the microglia polarization shift from the M1 phenotype and skewed toward the M2 phenotype. Additionally, SRT1720 significantly decreased acetylation of forkhead box protein O1, inhibited the overproduction of reactive oxygen species (ROS) and suppressed NLRP3 inflammasome signaling. In contrast, EX527 abated the upregulation of SIRT1 and reversed the inhibitory effects of SRT1720 on ROS-NLRP3 inflammasome activation and EBI. Similarly, in vitro, SRT1720 suppressed inflammatory response, oxidative damage, and neuronal degeneration, and improved cell viability in neurons and microglia co-culture system. These effects were associated with the suppression of ROS-NLRP3 inflammasome and stimulation of SIRT1 signaling, which could be abated by EX527. Altogether, these findings indicate that SRT1720, an SIRT1 agonist, can ameliorate EBI after SAH by shifting the microglial phenotype toward M2 via modulation of ROS-mediated NLRP3 inflammasome signaling.

SIRT1: A Potential Therapeutic Target in Autoimmune Diseases.

The morbidity and mortality of autoimmune diseases (Ads) have been increasing worldwide, and the identification of novel therapeutic strategies for prevention and treatment is urgently needed. Sirtuin 1 (SIRT1), a member of the class III family of nicotinamide adenine dinucleotide (NAD+)-dependent histone deacetylases, has been reported to participate in the progression of several diseases. SIRT1 also regulates inflammation, oxidative stress, mitochondrial function, immune responses, cellular differentiation, proliferation and metabolism, and its altered functions are likely involved in Ads. Several inhibitors and activators have been shown to affect the development of Ads. SIRT1 may represent a novel therapeutic target in these diseases, and small molecules or natural products that modulate the functions of SIRT1 are potential therapeutic agents. In the present review, we summarize current studies of the biological functions of SIRT1 and its role in the pathogenesis and treatment of Ads.

MicroRNA-155-5p promotes neuroinflammation and central sensitization via inhibiting SIRT1 in a nitroglycerin-induced chronic migraine mouse model.

BACKGROUND: Previous studies have confirmed that the microglial activation and subsequent inflammatory responses in the trigeminal nucleus caudalis (TNC) are involved in the central sensitization of chronic migraine (CM). MicroRNA-155-5p has been shown to modulate the polarization of microglia and participate in inflammatory processes in a variety of neurological diseases. However, its role in CM remains unclear. The purpose of this study was to determine the precise role of miR-155-5p in CM. METHODS: A model of CM in C57BL/6 mice was established by recurrent intraperitoneal injection of nitroglycerin (NTG). Mechanical and thermal hyperalgesia were evaluated by Von Frey filaments and radiant heat. The expression of miR-155-5p was examined by qRT-PCR, and the mRNA and protein levels of silent information regulator 1(SIRT1) were measured by qRT-PCR, Western blotting (WB) and immunofluorescence (IF) analysis. The miR-155-5p antagomir, miR-155-5p agomir, SRT1720 (a SIRT1 activator) and EX527 (a SIRT1 inhibitor) were administered to confirm the effects of miR-155-5p and SIRT1 on neuroinflammation and the central sensitization of CM. ELISA, WB and IF assays were applied to evaluate the expression of TNF-α, myeloperoxidase (MPO), IL-10, p-ERK, p-CREB, calcitonin gene-related peptide (CGRP), c-Fos and microglial activation. The cellular localization of SIRT1 was illustrated by IF. RESULTS: After the NTG-induced mouse model of CM was established, the expression of miR-155-5p was increased. The level of SIRT1 was decreased, and partly colocalized with Iba1 in the TNC. The miR-155-5p antagomir and SRT1720 downregulated the expression of p-ERK, p-CREB, CGRP, and c-Fos, alleviating microglial activation and decreasing inflammatory substances (TNF-α, MPO). The administration of miR-155-5p agomir or EX527 exacerbated neuroinflammation and central sensitization. Importantly, the miR-155-5p agomir elevated CGRP and c-Fos expression and microglial activation, which could subsequently be alleviated by SRT1720. CONCLUSIONS: These data demonstrate that upregulated miR-155-5p in the TNC participates in the central sensitization of CM. Inhibiting miR-155-5p alleviates neuroinflammation by activating SIRT1 in the TNC of CM mice.

DRG2 Accelerates Senescence via Negative Regulation of SIRT1 in Human Diploid Fibroblasts.

Accumulating evidence suggests that developmentally regulated GTP-binding protein 2 (DRG2), an evolutionarily conserved GTP-binding protein, plays an important role in regulating cell growth, inflammation, and mitochondria dynamics. However, the effect of DRG2 in aging remains unclear. In this study, we found that endogenous DRG2 protein expression is upregulated in oxidative stress-induced premature senescence models and tissues of aged mice. Ectopic expression of DRG2 significantly promoted senescence-associated ß-galactosidase (SA-ß-gal) activity and inhibited cell growth, concomitant with increase in levels of acetyl (ac)-p53 (Lys382), ac-nuclear factor-kB (NF-κB) p65 (Lys310), p21 Waf1/Cip1 , and p16 Ink4a and a decrease in cyclin D1. In this process, reactive oxygen species (ROS) and phosphorylation of H2A histone family member X (H2A.X), forming γ-H2A.X, were enhanced. Mechanistically, ectopic expression of DRG2 downregulated Sirtuin-1 (SIRT1), resulting in augmented acetylation of p53 and NF-κB p65. Additionally, DRG2 knockdown significantly abolished oxidative stress-induced premature senescence. Our results provide a possible molecular mechanism for investigation of cellular senescence and aging regulated by DRG2.

Fucoxanthin regulates Nrf2 signaling to decrease oxidative stress and improves renal fibrosis depending on Sirt1 in HG-induced GMCs and STZ-induced diabetic rats.

Diabetic nephropathy (DN) is one of the major microvascular complications of diabetes. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a crucial cellular defense factor to cope with oxidative stress. Silent information regulator T1 (Sirt1) is a deacetylase with antioxidative stress activity. Fucoxanthin is a marine-derived carotenoid. This study was conducted to investigate whether fucoxanthin could alleviate oxidative stress by activating Sirt1/Nrf2 signaling to alleviate DN. In streptozotocin-induced diabetic rats, fucoxanthin treatment effectively improved renal function, alleviated glomerulosclerosis. Fucoxanthin reversed the decreased protein levels of Sirt1 and Nrf2 in the kidney of diabetic rats and glomerular mesangial cells cultured in high glucose. Conversely, EX527, a Sirt1 inhibitor, counteracted the effect of fucoxanthin on the expression of Nrf2. Furthermore, in vivo and vitro results showed that fucoxanthin treatment reversed the low expression and activity of superoxide dismutase and heme oxygenase 1, depending on Sirt1 activation. Our results suggest that fucoxanthin improves diabetic kidney function and renal fibrosis by activating Sirt1/Nrf2 signaling to reduce oxidative stress.

Regulation of Sirt1 on energy metabolism and immune response in rheumatoid arthritis.

Rheumatoid arthritis (RA) is a systemic autoimmune disease. Synovial hyperplasia and persistent inflammation serve as its typical pathological manifestations, which ultimately lead to joint destruction and function loss. Both clinical observations and metabolomics studies have revealed the prevalence of metabolic disorders in RA. In inflammatory immune microenvironments, energy metabolism is profoundly changed. Increasingly evidences suggest that this abnormality is involved in the occurrence and development of RA-related inflammation. Unsurprisingly, many energy metabolism sensors have been confirmed with immunoregulatory properties. As a representative, silent information regulator type 1 (Sirt1) controls many aspects of immune cells, such as cell lifespan, polarization, and secretion by functioning as a transcriptional regulator. Because of the profound clinical implication, researches on Sirt1 in the regulation of energy metabolism and immune functions under RA conditions have gradually gained momentum. This signaling balances glycolysis, lipid metabolism and insulin secretion orchestrating with other metabolism sensors, and consequently affects immune milieu through a so-called metabolism-immune feedback mechanism. This article reviews the involvement of Sirt1 in RA by discussing its impacts on energy metabolism and immune functions, and specially highlights the potential of Sirt1-targeting anti-rheumatic regimens. It also provides a theoretical basis for clarifying the mystery about the high incidence of metabolic complications in RA patients and identifying new anti-rheumatic reagents.

Synthetic modified Fezf2 mRNA (modRNA) with concurrent small molecule SIRT1 inhibition enhances refinement of cortical subcerebral/corticospinal neuron identity from mouse embryonic stem cells.

During late embryonic development of the cerebral cortex, the major class of cortical output neurons termed subcerebral projection neurons (SCPN; including the predominant population of corticospinal neurons, CSN) and the class of interhemispheric callosal projection neurons (CPN) initially express overlapping molecular controls that later undergo subtype-specific refinements. Such molecular refinements are largely absent in heterogeneous, maturation-stalled, neocortical-like neurons (termed "cortical" here) spontaneously generated by established embryonic stem cell (ES) and induced pluripotent stem cell (iPSC) differentiation. Building on recently identified central molecular controls over SCPN development, we used a combination of synthetic modified mRNA (modRNA) for Fezf2, the central transcription factor controlling SCPN specification, and small molecule screening to investigate whether distinct chromatin modifiers might complement Fezf2 functions to promote SCPN-specific differentiation by mouse ES (mES)-derived cortical-like neurons. We find that the inhibition of a specific histone deacetylase, Sirtuin 1 (SIRT1), enhances refinement of SCPN subtype molecular identity by both mES-derived cortical-like neurons and primary dissociated E12.5 mouse cortical neurons. In vivo, we identify that SIRT1 is specifically expressed by CPN, but not SCPN, during late embryonic and postnatal differentiation. Together, these data indicate that SIRT1 has neuronal subtype-specific expression in the mouse cortex in vivo, and that its inhibition enhances subtype-specific differentiation of highly clinically relevant SCPN / CSN cortical neurons in vitro.

High-resolution respirometry for evaluation of mitochondrial function on brain and heart homogenates in a rat model of cardiac arrest and cardiopulmonary resuscitation.

The physiology and physiopathology process of mitochondrial function following cardiac arrest remains poorly understood. We aimed to assess mitochondrial respiratory function on the heart and brain homogenates from cardiac arrest rats. The expression level of SIRT1/PGC-1α pathway was measured by immunoblotting. 30 rats were assigned to the CA group and the sham group. Rats of CA were subjected to 6 min of untreated ventricular fibrillation (VF) followed by 8 min of cardiopulmonary resuscitation (CPR). Mitochondrial respiratory function was compromised following CA and I/R injury, as indicated by CIL (451.46 ± 71.48 vs. 909.91 ± 5.51 pmol/min*mg for the heart and 464.14 ± 8.22 vs. 570.53 ± 56.33 pmol/min*mg for the brain), CI (564.04 ± 64.34 vs. 2729.52 ± 347.39 pmol/min*mg for the heart and 726.07 ± 85.78 vs. 1762.82 ± 262.04 pmol/min*mg for the brain), RCR (1.88 ± 0.46 vs. 3.57 ± 0.38 for the heart and 2.05 ± 0.19 vs. 3.49 ± 0.19, for the brain) and OXPHOS coupling efficiency (0.45 ± 0.11 vs. 0.72 ± 0.03 for the heart and 0.52 ± 0.05 vs. 0.71 ± 0.01 for the brain). However, routine respiration was lower in the heart and comparable in the brain after CA. CIV did not change in the heart but was enhanced in the brain. Furthermore, both SIRT1 and PGC-1α were downregulated concurrently in the heart and brain. The mitochondrial respiratory function was compromised following CA and I/R injury, and the major affected respiratory state is complex I-linked respiration. Furthermore, the heart and the brain respond differently to the global I/R injury after CA in mitochondrial respiratory function. Inhibition of the SIRT1/PGC-1α pathway may be a major contributor to the impaired mitochondrial respiratory function.

ACE2 Promotes the Synthesis of Pulmonary Surfactant to Improve AT II Cell Injury via SIRT1/eNOS Pathway.

OBJECTIVE: We aimed to explore the level of PS, cell viability, inflammatory factors, and apoptosis in neonatal respiratory distress syndrome (ARDS). Besides, we explored the potential relationship between ACE2, SIRT1/eNOS pathway, and hypoxia-induced AT II cell damage. METHODS: The hUC-MSC-derived AT II cells were verified by IF and ICC, whereas qRT-PCR was used for PS and AT II cell marker (CK-8 and KGF). The AT II cell damage model was established by hypoxia exposure. The enhanced expression of ACE2 was tested after transfection with pcDNA3.1-ACE2 by western blot. The effects of hypoxia and ACE2 on AT II cells were evaluated by MTT, western blot, ELISA, and flow cytometry. The involvement of the SIRT1/eNOS pathway in AT II cell's protective functions against NRDS was verified with the addition of SIRT1 inhibitor EX527. RESULTS: Based on the successful differentiation of AT II cells from hUC-MSCs and the buildup of AT II cell damage model, the overexpressed ACE2 impeded the hypoxia-induced cellular damage of AT II cells. It also counteracted the inhibitory effects of hypoxia on the secretion of PS. Overexpression of ACE2 rescued the cell viability and suppressed the secretion of inflammatory cytokines and the apoptosis of AT II cells triggered by hypoxia. And ACE2 activated the SIRT1/eNOS pathway to play its cell-protective and anti-inflammatory roles. CONCLUSION: Our findings provided information that ACE2 prevented AT II cells from inflammatory damage through activating the SIRT1/eNOS pathway, which suggested that ACE2 might become a novel protective agent applied in the protection and treatment of NRDS.

Identification of isoform/domain-selective fragments from the selection of DNA-encoded dynamic library.

DNA-encoded chemical library (DEL) has emerged to be a powerful ligand screening technology in drug discovery. Recently, we reported a DNA-encoded dynamic library (DEDL) approach that combines the principle of traditional dynamic combinatorial library (DCL) with DEL. DEDL has shown excellent potential in fragment-based ligand discovery with a variety of protein targets. Here, we further tested the utility of DEDL in identifying low molecular weight fragments that are selective for different isoforms or domains of the same protein family. A 10,000-member DEDL was selected against sirtuin-1, 2, and 5 (SIRT1, 2, 5) and the BD1 and BD2 domains of bromodomain 4 (BRD4), respectively. Albeit with modest potency, a series of isoform/domain-selective fragments were identified and the corresponding inhibitors were derived by fragment linking.

Quercetin alleviates cadmium chloride-induced renal damage in rats by suppressing endoplasmic reticulum stress through SIRT1-dependent deacetylation of Xbp-1s and eIF2α.

Endoplasmic reticulum (ER) stress plays a key role in cadmium chloride (CdCl2)-induced nephrotoxicity. Sirtuin-1 (SIRT1) is a potent inhibitor of ER stress. In this study, we examined whether the protective effect of quercetin (QUR) against CdCl2-induced nephrotoxicity in rats involved modulation of SIRT1 and/or ER stress. Adult male rats were divided into five groups (n = 8, each) and treated for eight weeks as follows: control, control + QUR, CdCl2, CdCl2 + QUR, and CdCl2 + QUR + EX-527 (a SIRT1 inhibitor). Treatment of rats with QUR preserved the glomerulus and tubule structure, attenuated interstitial fibrosis, increased creatinine excretion, and reduced urinary levels of albumin, N-acetyl-ß-D-glucosaminidase, and ß2-microglobulin in CdCl2-treated rats. Concomitantly, QUR increased renal levels of Bcl-2, reduced mRNA levels of CHOP, and protein levels of Bax, caspase-3, and cleaved caspase-3, but failed to reduce the mRNA levels of GRP78, PERK, eIf2α, ATF-6, and xbp-1. QUR also reduced the renal levels of reactive oxygen species, tumour necrosis factor, and interleukin-6 and the nuclear activity of NF-κB in the control and CdCl2-treated rats but increased the nuclear activity of Nrf2 and levels of glutathione and manganese superoxide dismutase. Additionally, QUR increased the total levels and nuclear activity of SIRT1 and reduced the acetylation of eIf2α and xbp-1. The nephroprotective effects of QUR were abrogated by treatment with EX-527. Thus, QUR ameliorated CdCl2-induced nephrotoxicity through antioxidant and anti-inflammatory effects and suppressed ER stress mediated by the upregulation or activation of SIRT1-induced deacetylation of Nrf2, NF-κB p65, eIF2α, and xbp-1.

Protectin conjugates in tissue regeneration 1 restores lipopolysaccharide-induced pulmonary endothelial glycocalyx loss via ALX/SIRT1/NF-kappa B axis.

BACKGROUND: Endothelial glycocalyx loss is integral to increased pulmonary vascular permeability in sepsis-related acute lung injury. Protectin conjugates in tissue regeneration 1 (PCTR1) is a novel macrophage-derived lipid mediator exhibiting potential anti-inflammatory and pro-resolving benefits. METHODS: PCTR1 was administrated intraperitoneally with 100 ng/mouse after lipopolysaccharide (LPS) challenged. Survival rate and lung function were used to evaluate the protective effects of PCTR1. Lung inflammation response was observed by morphology and inflammatory cytokines level. Endothelial glycocalyx and its related key enzymes were measured by immunofluorescence, ELISA, and Western blot. Afterward, related-pathways inhibitors were used to identify the mechanism of endothelial glycocalyx response to PCTR1 in mice and human umbilical vein endothelial cells (HUVECs) after LPS administration. RESULTS: In vivo, we show that PCTR1 protects mice against lipopolysaccharide (LPS)-induced sepsis, as shown by enhanced the survival and pulmonary function, decreased the inflammatory response in lungs and peripheral levels of inflammatory cytokines such as tumor necrosis factor-α, interleukin-6, and interleukin-1ß. Moreover, PCTR1 restored lung vascular glycocalyx and reduced serum heparin sulphate (HS), syndecan-1 (SDC-1), and hyaluronic acid (HA) levels. Furthermore, we found that PCTR1 downregulated heparanase (HPA) expression to inhibit glycocalyx degradation and upregulated exostosin-1 (EXT-1) protein expression to promote glycocalyx reconstitution. Besides, we observed that BAY11-7082 blocked glycocalyx loss induced by LPS in vivo and in vitro, and BOC-2 (ALX antagonist) or EX527 (SIRT1 inhibitor) abolished the restoration of HS in response to PCTR1. CONCLUSION: PCTR1 protects endothelial glycocalyx via ALX receptor by regulating SIRT1/NF-κB pathway, suggesting PCTR1 may be a significant therapeutic target for sepsis-related acute lung injury.