bims-nadaut Biomed News
on NAD and autophagy
Issue of 2023‒09‒03
seven papers selected by
Niall Wilson, Newcastle University

  1. Toxicol In Vitro. 2023 Aug 26. pii: S0887-2333(23)00132-7. [Epub ahead of print] 105683
      Oxidative stress causes endothelial dysfunction, which is associated with vascular cellular aging and is causally related to cardiovascular disease pathogenesis. Preclinical studies indicate that a nicotinamide adenine dinucleotide (NAD+) precursor, nicotinamide mononucleotide (NMN), alleviates oxidative stress in aged vessels, granting vasoprotective effects. However, the associated cellular mechanism remains largely unclear. In this study, we used human umbilical vein endothelial cells (HUVECs) to demonstrate that NMN inhibits oxidative stress-induced damage by activating the sirtuin 1 (SIRT1)/NAD(P)H: quinone oxidoreductase 1 (NQO-1) axis. We found that NMN inhibited H2O2-induced cytotoxicity and senescence-associated protein expression, such as p16 and p21. Furthermore, NMN prevented H2O2-induced actin cytoskeletal disorganization via inhibiting reactive oxygen species (ROS) production. NMN increased NQO-1 mRNA and protein expression that in turn was abrogated by SIRT1 inhibition, suggesting that NMN-inducible NQO-1 was associated with SIRT1 activity. SIRT1 and NQO-1 inhibition attenuated the inhibitory effect of NMN on H2O2-inducible cytotoxicity, senescence-related protein upregulation, and actin cytoskeletal disorganization. Our findings provide new insights into the mechanism by which NMN exerts protective effects against vascular oxidative stress.
    Keywords:  HUVEC; NQO1; Nicotinamide mononucleotide; Oxidative stress; Senescence; Sirtuin
  2. Cell Rep. 2023 Aug 26. pii: S2211-1247(23)01037-9. [Epub ahead of print]42(9): 113026
      Wallerian axonal degeneration (WD) does not occur in the nematode C. elegans, in contrast to other model animals. However, WD depends on the NADase activity of SARM1, a protein that is also expressed in C. elegans (ceSARM/ceTIR-1). We hypothesized that differences in SARM between species might exist and account for the divergence in WD. We first show that expression of the human (h)SARM1, but not ceTIR-1, in C. elegans neurons is sufficient to confer axon degeneration after nerve injury. Next, we determined the cryoelectron microscopy structure of ceTIR-1 and found that, unlike hSARM1, which exists as an auto-inhibited ring octamer, ceTIR-1 forms a readily active 9-mer. Enzymatically, the NADase activity of ceTIR-1 is substantially weaker (10-fold higher Km) than that of hSARM1, and even when fully active, it falls short of consuming all cellular NAD+. Our experiments provide insight into the molecular mechanisms and evolution of SARM orthologs and WD across species.
    Keywords:  C. elegans; CP: Molecular biology; CP: Neuroscience; NAD(+) metabolism; SARM1; TIR-1; Wallerian degeneration; axon; cryo-EM; neurodegeneration; structural biology
  3. J Ethnopharmacol. 2023 Aug 26. pii: S0378-8741(23)00957-1. [Epub ahead of print]319(Pt 1): 117089
      ETHNOPHARMACOLOGICAL RELEVANCE: Ginseng (Panax ginseng C. A. Mey) is a common traditional Chinese medicine used for anti-inflammation, treating colitis, type 2 diabetes, diarrhea, and recovering hepatobiliary function. Ginsenosides, the main active components isolated from ginseng, possess liver and gallbladder diseases therapeutic potential.AIMS OF THE STUDY: Cholestatic liver injury (CLI) is a liver disease induced by intrahepatic accumulation of toxic bile acids and currently lacks clinically effective drugs. Our previous study found that ginsenosides alleviated CLI by activating sirtuin 1 (SIRT1), but the effective ingredients and the underlying mechanism have not been clarified. This study aimed to identify an effective ingredient with the most significant activation effect on SIRT1 from the five major monomer saponins of ginsenosides: Rb1, Rd, Rg1, 20s-Rg3, and Rc further explore its protective effects on CLI, and elaborate its underlying mechanism.
    MATERIALS AND METHODS: Discovery Studio 3.0 was used to conduct molecular docking between monomer saponins and SIRT1, and further detect the influence of monomer saponins on SIRT1 activity in vitro. Finally, it was determined that Rg1 had the most significant stimulative effect on SIRT1, and the hepatoprotective activity of Rg1 in CLI was explored in vivo. Wild-type mice were intragastrically α-naphthylisothiocyanate (ANIT) to establish an experimental model of intrahepatic cholestasis and Rg1 intervention, and then liver injury and cholestasis related indexes were detected. In addition, Liver-specific SIRT1 gene knockout (SIRT1-/-) mice were administered with ANIT and/or Rg1 to further investigate the mechanism of action of Rg1.
    RESULTS: The results of molecular docking and in vitro experiments showed that all the five ginsenoside monomers could bind to the active site of SIRT1 and promote SIRT1 activity in HepG2 cells. Among them, Rg1 exhibited the most significant stimulation of SIRT1 activity in cholestasis. Besides, it could ameliorate ANIT-induced inflammation and oxidative stress in HepG2 cells. Therefore, we investigated the hepatoprotective effect and mechanism of Rg1 on CLI. Results showed that Rg1 reversed the ANIT-induced increase in biochemical parameters, improved liver pathological injury, and decreased liver lipid accumulation, reactive oxygen species and pro-inflammatory factor levels. Mechanistically, Rg1 induced SIRT1 expression, followed by promoted the activity of Nrf2 and suppressed the activation of NF-κB. Interestingly, the hepatoprotective effect of Rg1 was blocked in SIRT1-/- mice.
    CONCLUSION: Rg1 mitigated ANIT-induced CLI via upregulating SIRT1 expression, and our results suggested that Rg1 is a candidate compound for treating CLI.
    Keywords:  Cholestatic liver injury; Ginsenoside Rg1; Inflammation; Oxidative stress; SIRT1
  4. Biochem Soc Trans. 2023 Aug 31. pii: BST20221363. [Epub ahead of print]
      The removal of damaged mitochondrial components through a process called mitochondrial autophagy (mitophagy) is essential for the proper function of the mitochondrial network. Hence, mitophagy is vital for the health of all aerobic animals, including humans. Unfortunately, mitophagy declines with age. Many age-associated diseases, including Alzheimer's and Parkinson's, are characterized by the accumulation of damaged mitochondria and oxidative damage. Therefore, activating the mitophagy process with small molecules is an emerging strategy for treating multiple aging diseases. Recent studies have identified natural and synthetic compounds that promote mitophagy and lifespan. This article aims to summarize the existing knowledge about these substances. For readers' convenience, the knowledge is presented in a table that indicates the chemical data of each substance and its effect on lifespan. The impact on healthspan and the molecular mechanism is reported if known. The article explores the potential of utilizing a combination of mitophagy-inducing drugs within a therapeutic framework and addresses the associated challenges of this strategy. Finally, we discuss the process that balances mitophagy, i.e. mitochondrial biogenesis. In this process, new mitochondrial components are generated to replace the ones cleared by mitophagy. Furthermore, some mitophagy-inducing substances activate biogenesis (e.g. resveratrol and metformin). Finally, we discuss the possibility of combining mitophagy and biogenesis enhancers for future treatment. In conclusion, this article provides an up-to-date source of information about natural and synthetic substances that activate mitophagy and, hopefully, stimulates new hypotheses and studies that promote healthy human aging worldwide.
    Keywords:  aging; lifespan; mitochondria; mitochondrial autophagy; mitochondrial biogenesis; mitophagy
  5. Cell Biochem Funct. 2023 Aug 31.
      The biogenic synthesis of nanoparticles has drawn significant attention. The spleen is the largest lymphatic organ that is adversely impacted during irradiation. The current study was designated to evaluate the possible anti-inflammatory effect of matcha-silver nanoparticles (M-AgNPs) to reduce inflammation associated with γ-radiation induced-oxidative stress and inflammation in rats' spleen. Silver nanoparticles (AgNPs) were synthesized by biogenic synthesis using a green sonochemical method from matcha (M) green tea. The obtained M-AgNPs were extensively characterized by dynamic light scattering, transmission electron microscopy, thermogravimetric analysis, and Fourier-transform infrared spectroscopy. Using zetasizer analysis, the surface charge, particle size, and radical scavenging DPPH assay of M-AgNPs were also examined. Biocompatibility and cytotoxicity were analyzed by MTT assay, and the IC50 was calculated. Four groups of 24 Wistar rats each had an equal number of animals. The next step involved measuring the levels of oxidative stress markers in the rat splenic tissue. Additionally, the amounts of inflammatory protein expression were evaluated using the ELISA analysis. The results indicated the formation of spherical nanoparticles of pure Ag° coated with matcha polyphenols at the nanoscale, as well as uniform monodisperse particles suited for cellular absorption. Results revealed that M-AgNPs improved all biochemical parameters. Furthermore, M-AgNPs relieve inflammation by reducing the expression of NOD-like receptor family pyrin domain-containing 3 (NLRP3), interleukin-1β (IL-1β), and enhancing the levels of ileSnt information regulator 1 (SIRT1). Histopathological examinations demonstrated the ability of M-AgNPs to overcome the damage consequent to irradiation and recover the spleen's cellular structure. These results confirmed that matcha is a potential biomaterial for synthesizing AgNPs, which can be exploited for their anti-inflammatory activity.
    Keywords:  antioxidant activity; gamma radiation; inflammation; matcha; silver nanoparticles
  6. Diabetes Metab Syndr Obes. 2023 ;16 2593-2604
      Background: Diabetes retinopathy (DR) is a chronic, progressive, and potentially harmful retinal disease associated with persistent hyperglycemia. Autophagy is a lysosome-dependent degradation pathway that widely exists in eukaryotic cells, which has recently been demonstrated to participate in the DR development. Stachydrine (STA) is a water-soluble alkaloid extracted from Leonurus heterophyllus. This study aimed to explore the effects of STA on the autophagy in DR progression in vivo and in vitro.Methods: High glucose-treated human retinal microvascular endothelial cells (HRMECs) and STA-treated rats were used to establish DR model. The reactive oxygen species (ROS) and inflammatory factor levels (TNF-α, IL-1β, and IL-6) were determined using corresponding kits. Additionally, the cell growth was analyzed using CCK-8 and EdU assays. Besides, LC3BII, p62, p-AMPKα, AMPKα, and SIRT1 protein levels were measured using Western blot. The LC3BII and SIRT1 expressions were also determined using immunofluorescence.
    Results: The results showed that STZ decreased the ROS and inflammatory factor levels in the HG-treated HRMECs. Besides, after STA treatment, the beclin-1, LC3BII, p-AMPKα, and SIRT1 levels were increased, and p62 was decreased in the HG-treated HRMECs and the retinal tissue of STZ-treated rats.
    Conclusion: In conclusion, this study demonstrated that STA effectively relieved the inflammation and promoted the autophagy in DR progression in vivo and in vitro through activating the AMPK/SIRT1 signaling pathway.
    Keywords:  AMPK/SIRT1; autophagy; diabetes retinopathy; stachydrine
  7. Toxicol Appl Pharmacol. 2023 Aug 25. pii: S0041-008X(23)00310-1. [Epub ahead of print]476 116671
      Impaired fertility is the major side effect of chemotherapy for female cancer patients, accumulated evidence indicates this is associated with damage on oocyte quality, but the underlying mechanisms remain unclear. Previously we reported that doxorubicin (DXR) exposure, one of the most widely used chemotherapy drugs, disrupted mouse oocyte meiotic maturation in vitro. In the current study, we identified that SIRT1 expression was remarkably reduced in DXR exposure oocytes. Next, we found that increasing SIRT1 expression by resveratrol partially alleviated the effects of DXR exposure on oocyte maturation, which was counteracted by SIRT1 inhibition. Furthermore, we revealed that increasing SIRT1 expression mitigated DXR induced oocyte damage through reducing ROS levels, increasing antioxidant enzyme MnSOD expression, and preventing spindle and chromosome disorganization, lowering the incidence of aneuploidy. Importantly, by performing in vitro fertilization and embryo transfer assays, we demonstrated that increasing SIRT1 expression significantly improved the fertilization ability, developmental competence of oocytes and early embryos. In summary, our data uncover that SIRT1 reduction represents one mechanism that mediates the effects of DXR exposure on oocyte quality.
    Keywords:  Doxorubicin; Meiotic maturation; Oocyte; Oxidative stress; SIRT1