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Nature Jan 2022The DNA-dependent protein kinase catalytic subunit (DNA-PKcs) has a central role in non-homologous end joining, one of the two main pathways that detect and repair DNA...
The DNA-dependent protein kinase catalytic subunit (DNA-PKcs) has a central role in non-homologous end joining, one of the two main pathways that detect and repair DNA double-strand breaks (DSBs) in humans. DNA-PKcs is of great importance in repairing pathological DSBs, making DNA-PKcs inhibitors attractive therapeutic agents for cancer in combination with DSB-inducing radiotherapy and chemotherapy. Many of the selective inhibitors of DNA-PKcs that have been developed exhibit potential as treatment for various cancers. Here we report cryo-electron microscopy (cryo-EM) structures of human DNA-PKcs natively purified from HeLa cell nuclear extracts, in complex with adenosine-5'-(γ-thio)-triphosphate (ATPγS) and four inhibitors (wortmannin, NU7441, AZD7648 and M3814), including drug candidates undergoing clinical trials. The structures reveal molecular details of ATP binding at the active site before catalysis and provide insights into the modes of action and specificities of the competitive inhibitors. Of note, binding of the ligands causes movement of the PIKK regulatory domain (PRD), revealing a connection between the p-loop and PRD conformations. Electrophoretic mobility shift assay and cryo-EM studies on the DNA-dependent protein kinase holoenzyme further show that ligand binding does not have a negative allosteric or inhibitory effect on assembly of the holoenzyme complex and that inhibitors function through direct competition with ATP. Overall, the structures described in this study should greatly assist future efforts in rational drug design targeting DNA-PKcs, demonstrating the potential of cryo-EM in structure-guided drug development for large and challenging targets.
Topics: Adenosine Triphosphate; Catalytic Domain; Cryoelectron Microscopy; DNA; DNA End-Joining Repair; DNA Repair; DNA-Activated Protein Kinase; HeLa Cells; Holoenzymes; Humans; Ku Autoantigen; Pyridazines; Quinazolines
PubMed: 34987222
DOI: 10.1038/s41586-021-04274-9 -
Nutrients Dec 2022Hair loss remains a significant problem that is difficult to treat; therefore, there is a need to identify safe natural materials that can help patients with hair loss....
Hair loss remains a significant problem that is difficult to treat; therefore, there is a need to identify safe natural materials that can help patients with hair loss. We evaluated the hair anagen activation effects of limonin, which is abundant in immature citrus fruits. Limonin increased the proliferation of rat dermal papilla cells (rDPC) by changing the levels of cyclin D1 and p27, and increasing the number of BrdU-positive cells. Limonin increased autophagy by decreasing phosphorylated mammalian target of rapamycin levels and increasing the phospho-Raptor, ATG7 and LC3B. Limonin also activated the Wnt/β-catenin pathway by increasing phospho-β-catenin levels. XAV939, a Wnt/β-catenin inhibitor, inhibited these limonin-induced changes, including induced autophagy, BrdU-positive cells, and cell proliferation. Limonin increased the phosphorylated AKT levels in both two-dimensional cultured rDPC and three-dimensional spheroids. Treatment with the PI3K inhibitor wortmannin inhibited limonin-induced proliferation, and disrupted other limonin-mediated changes, including decreased p27, increased BrdU-positive cells, induced autophagy, and increased ATG7 and LC3B levels. Wortmannin also inhibited limonin-induced cyclin D1 and LC3 expression in spheroids. Collectively, these results indicate that limonin can enhance anagen signaling by activating autophagy via targeting the Wnt/β-catenin and/or PI3K/AKT pathways in rDPC, highlighting a candidate nutrient for hair loss treatment.
Topics: Animals; Rats; Alopecia; beta Catenin; Bromodeoxyuridine; Cell Proliferation; Cells, Cultured; Cyclin D1; Fruit; Hair Follicle; Limonins; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins c-akt; Wnt Signaling Pathway; Wortmannin
PubMed: 36558517
DOI: 10.3390/nu14245358 -
Nanomaterials (Basel, Switzerland) Oct 2021Evaluation of the uptake pathways in cells during exposure to nanoparticles (NPs) is key for risk assessment and the development of safer nanomaterials, as the...
Evaluation of the uptake pathways in cells during exposure to nanoparticles (NPs) is key for risk assessment and the development of safer nanomaterials, as the internalisation and fate of NPs is linked to their toxicity and mode of action. Here, we determined the uptake mechanisms activated during the internalisation of 10, 30, and 100 nm AgNPs by embryonic zebrafish cells (ZF4). The uptake results demonstrated an NP size- and time-dependent uptake, showing the highest total silver uptake for the smallest AgNP (10 nm) at the lowest exposure concentration (2.5 μg/mL) after 2 h, while after 24 h, the highest exposure concentration (10 μg/mL) of the 10 nm AgNPs revealed the highest cellular load at 8 pg/cell. Inhibition of the caveolae, clathrin, and macropinocytosis endocytic pathways by pharmaceutical inhibitors (genistein, chlorpromazine, and wortmannin respectively) revealed that uptake was mainly via macropinocytosis for the 10 nm AgNPs and via the caveolae-mediated pathway for the 30 and 100 nm AgNPs. The induction of autophagy was also strongly related to the NP size, showing the highest percentage of induction for the 10 nm (around 3%) compared to naive cells, suggesting that autophagy can be activated along with endocytosis to deal with exposure to NPs. TEM imaging revealed the distribution of NPs across the cytoplasm inside intracellular vesicles. An increase in Early Endosome formation (EE) was observed for the 30 and 100 nm sizes, whereas the 10 nm AgNPs disrupted the activity of EE. The data supports the establishment of adverse outcome pathways by increasing knowledge on the link between a molecular initiating event such as receptor-mediated endocytosis and an adverse outcome, as well as supporting the reduction of animal testing by using alternative testing models, such as fish cell lines.
PubMed: 34685144
DOI: 10.3390/nano11102699 -
International Journal of Cardiology.... Oct 2021Studies of insulin-like growth factor 1 (IGF-1) as a novel therapy for the treatment of cardiovascular diseases have proven promising. However, elevated IGF-1 levels...
BACKGROUND
Studies of insulin-like growth factor 1 (IGF-1) as a novel therapy for the treatment of cardiovascular diseases have proven promising. However, elevated IGF-1 levels have also been associated with poor patient outcomes in heart failure with reduced ejection fraction. IGF-1 therapy has additionally been shown to not be beneficial in the percutaneous coronary intervention setting. Although IGF-1 activation of the PI3K/Akt and ERK1/2 pathways have been demonstrated as cardioprotective, other cellular mechanisms have not been fully investigated.
METHODS
Neonatal rat cardiac myocytes (NCMs) and fibroblasts (NCFs) were isolated from 1 to 2-day old pups using enzymatic digestion. NCMs and NCFs were pre-treated with IGF binding protein 6, inhibitors for the PI3K/Akt Wortmannin, ERK1/2 U0126, Rho Associated Protein Kinase (ROCK) GSK576371, Apoptosis Signal-regulating Kinase-1 (ASK-1) G2261818A, and p38MAPK RWJ67657 pathways before stimulation with IGF-1 for 62 and 50 h, respectively. Cardiac myocyte hypertrophy and fibroblast collagen synthesis were determined by H-leucine and H-proline incorporation, respectively.
RESULTS
IGF-1 dose-dependently stimulated NCM hypertrophy and NCF collagen synthesis.Treatment with IGFBP6 and the kinase inhibitors, Wortmannin, U0126, GSK576371, G2261818A and RWJ67657 significantly inhibited IGF-1 stimulated NCM hypertrophy and NCF collagen synthesis.
CONCLUSION
This study is the first to demonstrate that IGF-1 treatment in NCMs and NCFs activates the ROCK, ASK-1 and p38MAPK pathways. Future research may be guided by consideration of the PI3K/Akt and ERK1/2 pathways potentially increasing collagen synthesis, and the utilisation of a biased agonist to reduce activation of the ROCK, ASK-1 and p38MAPK pathways to maximise cardioprotective benefit whilst mitigating risks.
PubMed: 34401470
DOI: 10.1016/j.ijcha.2021.100852 -
American Journal of Physiology.... Mar 2021Progesterone acts directly on vascular smooth muscle cells (VSMCs) through activation of membrane progesterone receptor α (mPRα)-dependent signaling to rapidly...
Progesterone acts directly on vascular smooth muscle cells (VSMCs) through activation of membrane progesterone receptor α (mPRα)-dependent signaling to rapidly decrease cytosolic Ca concentrations and induce muscle relaxation. However, it is not known whether this progesterone action involves uptake of Ca by the sarco/endoplasmic reticulum (SR) and increased sarco/endoplasmic reticulum Ca-ATPase (SERCA) activity. The present results show that treatment of cultured human VSMCs with progesterone and the selective mPR agonist Org OD-02-0 (OD 02-0) but not with the nuclear PR agonist R5020 increased SERCA protein expression, which was blocked by knockdown of mPRα with siRNA. Moreover, treatments with progesterone and OD 02-0, but not with R5020, increased phospholamban (PLB) phosphorylation, which would result in disinhibition of SERCA function. Progesterone and OD 02-0 significantly increased Ca levels in the SR and caused VSMC relaxation. These effects were blocked by pretreatment with cyclopiazonic acid (CPA), a SERCA inhibitor, and by knockdown of SERCA2 with siRNA, suggesting that SERCA2 plays a critical role in progesterone induction of VSMC relaxation. Treatment with inhibitors of inhibitory G proteins (Gi, NF023), MAP kinase (AZD 6244), Akt/Pi3k (wortmannin), and a Rho activator (calpeptin) blocked the progesterone- and OD 02-0-induced increase in Ca levels in the SR and SERCA expressions. These results suggest that the rapid effects of progesterone on cytosolic Ca levels and relaxation of VSMCs through mPRα involve regulation of the functions of SERCA2 and PLB through Gi, MAP kinase, and Akt signaling pathways and downregulation of RhoA activity. The rapid effects of progesterone on cytosolic Ca levels and relaxation of VSMCs through mPRα involve regulation of the functions of SERCA2 and PLB through Gi, MAP kinase, and Akt signaling pathways and downregulation of RhoA activity.
Topics: Cells, Cultured; Gene Expression Regulation, Enzymologic; Humans; Muscle Relaxation; Muscle, Smooth, Vascular; Myocytes, Smooth Muscle; Progesterone; Receptors, Progesterone; Sarcoplasmic Reticulum Calcium-Transporting ATPases; Signal Transduction; Umbilical Arteries
PubMed: 33427050
DOI: 10.1152/ajpendo.00359.2020 -
Clinical, Cosmetic and Investigational... 2022Autophagy is an important process for maintaining intracellular homeostasis and is deregulated in ultraviolet B (UVB)-induced skin injury. Salidroside (SAL) is an active...
INTRODUCTION
Autophagy is an important process for maintaining intracellular homeostasis and is deregulated in ultraviolet B (UVB)-induced skin injury. Salidroside (SAL) is an active ingredient extracted from , which is a herbal medicine that has shown protection against ultraviolet (UV) radiation. Here, we investigated the functions and mechanisms of SAL on UVB-induced skin cell oxidative damage and autophagy.
METHODS
Human immortalized keratinocyte cell line HaCaT was used as a cell model of UV injury. HaCaT cells were exposed to UVB irradiation and then incubated with SAL to investigate cell viability, lactate dehydrogenase (LSD) in culture media, intracellular reactive oxygen species (ROS) level, oxidative stress, autophagy, and regulatory effects on SIRT1 protein.
RESULTS
SAL pretreatment (25, 50 and 100 μM) increased cell viability and inhibited LDH release in UVB-challenged HaCaT cells. SAL (100 μM) significantly reduced intracellular ROS level and suppressed oxidative stress, with increased MDA content and increased SOD activity. In addition, SAL pretreatment enhanced autophagy in UVB-irradiated HaCaT cells, increased protein expressions of Beclin-1 and ATG7, and decreased protein expression of P62. We also found that pretreatment with SAL increased the SIRT1 protein in irradiated HaCaT cells. SAL protected UVB-induced damage in a dependent manner on autophagy and SIRT1, as SAL-induced increase in viability was significantly attenuated by specific autophagy inhibitor Wortmannin (1 μM) or SIRT1 inhibitor EX-527 (100 nM).
DISCUSSION
The present study results speculate that SAL suppresses UVB-induced injury and autophagy by enhancing SIRT1 expression.
PubMed: 35941856
DOI: 10.2147/CCID.S367233 -
American Journal of Physiology.... Mar 2020Excess androgen-induced obesity has become a public health problem, and its prevalence has increased substantially in recent years. Chemokine-like receptor 1 (CMKLR1), a...
Excess androgen-induced obesity has become a public health problem, and its prevalence has increased substantially in recent years. Chemokine-like receptor 1 (CMKLR1), a receptor of chemerin secreted by adipose tissue, is linked to adipocyte differentiation, adipose tissue development, and obesity. However, the effect of CMKLR1 signaling on androgen-mediated adiposity in vivo remains unclear. Using CMKLR1-knockout mice, we constructed an androgen-excess female mouse model through 5α-dihydrotestosterone (DHT) treatment and an androgen-deficient male mouse model by orchidectomy (ORX). For mechanism investigation, we used 2-(α-Naphthoyl) ethyltrimethylammonium iodide (α-NETA), an antagonist of CMKLR1, to suppress CMKLR1 in vivo and wortmannin, a PI3K signaling antagonist, to treat brown adipose tissue (BAT) explant cultures in vitro Furthermore, we used histological examination and quantitative PCR, as well as Western blot analysis, glucose tolerance tests, and biochemical analysis of serum, to describe the phenotypes and the changes in gene expression. We demonstrated that excess androgen in the female mice resulted in larger cells in the white adipose tissue (WAT) and the BAT, whereas androgen deprivation in the male mice induced a reduction in cell size. Both of these adipocyte size effects could be attenuated in the CMKLR1-knockout mice. CMKLR1 deficiency influenced the effect of androgen treatment on adipose tissue by regulating the mRNA expression of the androgen receptor (AR) and adipocyte markers (such as Fabp4 and Cidea). Moreover, suppression of CMKLR1 by α-NETA could also reduce the extent of the adipocyte cell enlargement caused by DHT. Furthermore, we found that DHT could reduce the levels of phosphorylated ERK (pERK) in the BAT, while CMKLR1 inactivation inhibited this effect, which had been induced by DHT, through the PI3K signaling pathway. These findings reveal an antiobesity role of CMKLR1 deficiency in regulating lipid accumulation, highlighting the scientific importance for the further development of small-molecule CMKLR1 antagonists as fundamental research tools and/or as potential drugs for use in the treatment of adiposity.
Topics: Adipocytes; Adipose Tissue, Brown; Androgens; Animals; Body Weight; Cell Size; Dihydrotestosterone; Female; Lipid Metabolism; MAP Kinase Signaling System; Male; Mice; Mice, Inbred C57BL; Mice, Knockout; Naphthalenes; Phosphatidylinositol 3-Kinases; Protein Kinase Inhibitors; Quaternary Ammonium Compounds; Receptors, Chemokine; Wortmannin
PubMed: 31910029
DOI: 10.1152/ajpendo.00176.2019 -
Cell Death & Disease Apr 2022As the main extracellular matrix-producing cells, activated hepatic stellate cells (HSC) are fundamental mediators of liver fibrosis (LF), and understanding their...
As the main extracellular matrix-producing cells, activated hepatic stellate cells (HSC) are fundamental mediators of liver fibrosis (LF), and understanding their activation/inactivation mechanisms is paramount to the search for novel therapeutics. The antiretroviral drug Rilpivirine (RPV) has demonstrated a hepatoprotective effect in several animal models of chronic liver injury that is related to its antifibrogenic and apoptotic action in HSC. In the present study, we evaluated whether autophagy is implicated in the hepatoprotective action of RPV, as autophagy plays an important role in HSC transdifferentiation. We employed two standard mouse models of chronic liver injury - fatty liver disease and carbon tetrachloride (CCl)-induced hepatotoxicity -and cultured HSC activated with the profibrotic cytokine TGF-β. RPV enhanced autophagy in the whole liver of both mouse models and in activated HSC, evident in the protein expression of autophagy markers, increased autophagosome content and lysosomal mass. Moreover, increased autophagic flux was observed in RPV-exposed HSC as revealed by tandem fluorescence-tagged LC3 and p62 and analysis of LC3-II accumulation in cells exposed to the lysosomal inhibitor chloroquine. Importantly, autophagy was involved in the cytotoxic effect of RPV on HSC, though in a differential manner. Pharmacological inhibition of autophagy by 3-methyladenine (3-MA) did not affect the diminishing effect of RPV on viability, while treatment with wortmannin or depletion of specific autophagy proteins (ATG5, Beclin-1 and SQSTM1/p62) rescued the detrimental effect of high concentrations of RPV on the viability of activated HSC. Finally, we also provide evidence that RPV compromises the viability of TGF-β-induced HSC independently of its antifibrogenic effect, observed as reduced collagen 1A1 synthesis, and that this effect does not include RPV´s modulation of autophagy. In summary, as a contributor to the mechanisms involved in the hepatoprotective action of RPV, autophagy may be a good candidate to explore when developing novel therapeutics for LF.
Topics: Animals; Autophagy; Disease Models, Animal; Hepatic Stellate Cells; Liver Cirrhosis; Mice; Rilpivirine; Transforming Growth Factor beta
PubMed: 35443746
DOI: 10.1038/s41419-022-04789-7 -
Frontiers in Pharmacology 2022Osteoblast dysfunction, induced by high glucose (HG), negatively impacts bone homeostasis and contributes to the pathology of diabetic osteoporosis (DOP). One of the...
Osteoblast dysfunction, induced by high glucose (HG), negatively impacts bone homeostasis and contributes to the pathology of diabetic osteoporosis (DOP). One of the most widely recognized mechanisms for osteoblast dysfunction is oxidative stress. Resveratrol (RES) is a bioactive antioxidant compound to combat oxidative damage. However, its role in the protection of HG-induced osteoblast dysfunction has not been clarified. Therefore, our study aimed to explore potential regulatory mechanisms of RES for attenuating HG-induced osteoblast dysfunction. Our results showed that osteoblast dysfunction under HG condition was significantly ameliorated by RES the activation of nuclear factor erythroid 2-related factor (NRF2) to suppress oxidative stress. Furthermore, using -shRNA and wortmannin, we identified that activation of NRF2 RES was regulated by the AKT/glycogen synthase kinase 3β (GSK3β)/FYN axis.
PubMed: 35677434
DOI: 10.3389/fphar.2022.862618 -
Aging Oct 2021Allicin is an allyl 2-propenethiosulfinate or diallyl thiosulfinate acid with cardioprotective effects in myocardial ischemia/reperfusion (MI/R) injury. This study aims...
OBJECTIVES
Allicin is an allyl 2-propenethiosulfinate or diallyl thiosulfinate acid with cardioprotective effects in myocardial ischemia/reperfusion (MI/R) injury. This study aims to examine the underlying mechanism by which Allicin protects against MI/R.
METHODS
C57BL6 mice were subjected to either sham or MI/R surgery, and mice in the Allicin group were injected with Allicin (5 mg/ml) before the induction of ischemia. The cardiac function and histopathology of experimental mice were evaluated by ultrasound quantification and Masson staining. We next measured the capillary angiogenesis of the peri-infarct area by Masson staining and immunohistochemical staining. The miRNA microarray was carried out to examine the expressed miRNAs in MI/R tissues and corresponding normal tissues. Real-time quantitative polymerase chain reaction (q-PCR) was performed to validate the selected miRNA-19α-3p gene expression. Besides, we evaluated the myocardial lactate dehydrogenase and COX-2 by immunofluorescence staining. The western blot analysis was used to evaluate the protein levels of p-AKT, p-PI3K, p-mTOR, COX-2, and VEGF protein in the Allicin and Model group. study, LPS stimulated Tie2 expressing macrophages were cultured in an ischemic buffer. We evaluated the accumulation of VEGF by fura-2/AM fluorescence. Besides, Western blotting was performed to examine the protein levels of p-PI3K, p-AKT, p-mTOR, VEGF, COX2, and MMP2. The PI3K inhibitor was applied to investigate whether Allicin-induced myocardial ischemia-reperfusion injury protection is mediated via the PI3K/AKT pathway. And the miR-19α-3p mimic/inhibitor were transfected to promote/inhibit the expression of miR-19a-3p for verifying the regulation of miR-19a-3p on PI3K pathway.
RESULTS
Allicin pretreatment significantly improved I/R-induced cardiac function damage. Furthermore, Allicin could repress cardiac fibrosis, as evidenced by reduced areas of cardiac fibrosis. Allicin's effect on the MI/R was associated with increased capillary angiogenesis. Microarray analysis exposed that miR-19a-3p down-regulated PIK3CA (PI3K) expression by directly targeting the PIK3CA gene. The regulation of the angiogenesis pathway and gene miRNA-19a-3p might affect the Allicin-induced MI/R protection. Immunofluorescence staining revealed that COX-2 and myocardial lactate dehydrogenase were significantly increased after Allicin treatment. Furthermore, western blot analysis demonstrated that p-AKT, p-PI3K, p-mTOR, COX-2, and VEGF protein levels were also increased in the Allicin group. study, the protein levels of p-PI3K, p-AKT, p-mTOR, VEGF, COX2, and MMP2 were significantly increased in the Allicin-treated Tie2 expressing macrophages. These effects were partially reversed by PI3K inhibitor (Wortmannin) treatment. MiR-19α-3p plays an important role in myocardial I/R injury. It could regulate the activity of the PI3K-AKT pathway. And inhibition of miR-19a-3p promoted angiogenesis by regulating PI3K/AKT pathway.
CONCLUSIONS
Allicin pretreatment protects against myocardial I/R and activating the miR-19a-3p/PI3K/AKT pathway.
Topics: Animals; Cells, Cultured; Cyclooxygenase 2; Disulfides; Gene Expression Regulation; L-Lactate Dehydrogenase; Macrophages; Male; Mice; MicroRNAs; Myocardial Ischemia; Neovascularization, Physiologic; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins c-akt; Reperfusion Injury; Signal Transduction; Sulfinic Acids; Vascular Endothelial Growth Factor A
PubMed: 34607973
DOI: 10.18632/aging.203578