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result(s) for
"Han, Daewon"
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Sestrin2 protects against cholestatic liver injury by inhibiting endoplasmic reticulum stress and NLRP3 inflammasome-mediated pyroptosis
2022
Chronic exposure to bile acid in the liver due to impaired bile flow induces cholestatic liver disease, resulting in hepatotoxicity and liver fibrosis. Sestrin2, a highly conserved, stress-inducible protein, has been implicated in cellular responses to multiple stress conditions and the maintenance of cellular homeostasis. However, its role in cholestatic liver injury is not fully understood. In this study, we investigated the role of hepatic Sestrin2 in cholestatic liver injury and its underlying mechanisms using in vivo and in vitro approaches. Hepatic Sestrin2 expression was upregulated by activating transcription factor 4 (ATF4) and CCAAT/enhancer-binding protein-β (C/EBP-β) after treatment with bile acids and correlated with endoplasmic reticulum (ER) stress responses. Bile-duct ligation (BDL)-induced hepatocellular apoptosis and liver fibrosis were exacerbated in Sestrin2-knockout (
Sesn2
−/−
) mice. Moreover, Sestrin2 deficiency enhanced cholestasis-induced hepatic ER stress, whereas Sestrin2 overexpression ameliorated bile acid-induced ER stress. Notably, the mammalian target of rapamycin (mTOR) inhibitor rapamycin and the AMP-activated protein kinase (AMPK) activator AICAR reversed bile acid-induced ER stress in Sestrin2-deficient cells. Furthermore, Sestrin2 deficiency promoted cholestasis-induced hepatic pyroptosis by activating NLRP3 inflammasomes. Thus, our study provides evidence for the biological significance of Sestrin2 and its relationship with cholestatic liver injury, suggesting the potential role of Sestrin2 in regulating ER stress and inflammasome activation during cholestatic liver injury.
Liver disease: Minimizing the stress from bile blockage
A protein that manages the response to cellular stress can help prevent disruptions in bile flow from progressing to liver fibrosis or failure. Disrupted flow leads to the accumulation of bile acids, which triggers a state known as endoplasmic reticulum (ER) stress, fueling inflammation and eventual cell death. Researchers led by Hwan-Woo Park and Jongdae Shin at Konyang University, Daejon, South Korea, have demonstrated that the Sestrin2 protein plays a prominent role in managing this ER stress response to cytotoxic bile acids in cultured liver cells. They subsequently used a Sestrin2-deficient mouse model to demonstrate that the absence of this protein contributes to heightened ER stress and greatly increased liver damage following impaired bile flow. These results suggest that Sestrin2 modulators could offer effective treatments for liver disorders associated with bile flow obstruction.
Journal Article
SIRT1 Alleviates LPS-Induced IL-1β Production by Suppressing NLRP3 Inflammasome Activation and ROS Production in Trophoblasts
2020
Emerging evidence indicates that aberrant maternal inflammation is associated with several pregnancy-related disorders such as preeclampsia, preterm birth, and intrauterine growth restriction. Sirtuin1 (SIRT1), a class III histone deacetylase, is involved in the regulation of various physiopathological processes including cellular inflammation and metabolism. However, the effect of SIRT1 on the placental proinflammatory environment remains to be elucidated. In this study, we investigated the effect of SIRT1 on lipopolysaccharide (LPS)-induced NLRP3 inflammasome activation and its underlying mechanisms in human first-trimester trophoblasts (Sw.71 and HTR-8/SVneo cells). Treatment with LPS elevated SIRT1 expression and induced NLRP3 inflammasome activation in mouse placental tissues and human trophoblasts. Knockdown of SIRT1 enhanced LPS-induced NLRP3 inflammasome activation, inflammatory signaling, and subsequent interleukin (IL)-1β secretion. Furthermore, knockdown of NLRP3 considerably attenuated the increase of IL-1β secretion in SIRT1-knockdown cells treated with LPS. Moreover, SIRT1 inhibited LPS-induced NLRP3 inflammasome activation by reducing oxidative stress. This study revealed a novel mechanism via which SIRT1 exerts anti-inflammatory effects, suggesting that SIRT1 is a potential therapeutic target for the prevention of inflammation-associated pregnancy-related complications.
Journal Article
Methylsulfonylmethane ameliorates metabolic-associated fatty liver disease by restoring autophagy flux via AMPK/mTOR/ULK1 signaling pathway
by
Kim, Jeong Sig
,
Kim, Deokryong
,
Lee, Jeonga
in
AMP-activated protein kinase
,
AMPK/mTOR
,
Autophagy
2023
Introduction: Metabolism-associated fatty liver disease (MAFLD) is a global health concern because of its association with obesity, insulin resistance, and other metabolic abnormalities. Methylsulfonylmethane (MSM), an organic sulfur compound found in various plants and animals, exerts antioxidant and anti-inflammatory effects. Here, we aimed to assess the anti-obesity activity and autophagy-related mechanisms of Methylsulfonylmethane. Method: Human hepatoma (HepG2) cells treated with palmitic acid (PA) were used to examine the effects of MSM on autophagic clearance. To evaluate the anti-obesity effect of MSM, male C57/BL6 mice were fed a high-fat diet (HFD; 60% calories) and administered an oral dose of MSM (200 or 400 mg/kg/day). Moreover, we investigated the AMP-activated protein kinase (AMPK)/mechanistic target of rapamycin complex 1 (mTORC1)/UNC-51-like autophagy-activating kinase 1 (ULK1) signaling pathway to further determine the underlying action mechanism of MSM. Results: Methylsulfonylmethane treatment significantly mitigated PA-induced protein aggregation in human hepatoma HepG2 cells. Additionally, Methylsulfonylmethane treatment reversed the PA-induced impairment of autophagic flux. Methylsulfonylmethane also enhanced the insulin sensitivity and significantly suppressed the HFD-induced obesity and hepatic steatosis in mice. Western blotting revealed that Methylsulfonylmethane improved ubiquitinated protein clearance in HFD-induced fatty liver. Remarkably, Methylsulfonylmethane promoted the activation of AMPK and ULK1 and inhibited mTOR activity. Conclusion: Our study suggests that MSM ameliorates hepatic steatosis by enhancing the autophagic flux via an AMPK/mTOR/ULK1-dependent signaling pathway. These findings highlight the therapeutic potential of MSM for obesity-related MAFLD treatment.
Journal Article
Verapamil-loaded supramolecular hydrogel patch attenuates metabolic dysfunction-associated fatty liver disease via restoration of autophagic clearance of aggregated proteins and inhibition of NLRP3
2023
Background
Obesity, a serious threat to public health, is linked to chronic metabolic complications including insulin resistance, type-2 diabetes, and metabolic dysfunction-associated fatty liver disease (MAFLD). Current obesity medications are challenged by poor effectiveness, poor patient compliance, and potential side effects. Verapamil is an inhibitor of L-type calcium channels, FDA-approved for the treatment of hypertension. We previously investigated the effect of verapamil on modulating autophagy to treat obesity-associated lipotoxicity. This study aims to develop a verapamil transdermal patch and to evaluate its anti-obesity effects.
Methods
Verapamil is loaded in biomimetic vascular bundle-like carboxymethyl pullulan-based supramolecular hydrogel patches cross-linked with citric acid and glycerol linkages (CLCMP). The investigation was then carried out to determine the therapeutic effect of verapamil-loaded CLCMP (Vera@CLCMP) on diet-induced obese mice.
Results
Vera@CLCMP hydrogel patches with hierarchically organized and anisotropic pore structures not only improved verapamil bioavailability without modifying its chemical structure but also enhanced verapamil release through the stratum corneum barrier. Vera@CLCMP patches exhibit low toxicity and high effectiveness at delivering verapamil into the systemic circulation through the dermis in a sustained manner. Specifically, transdermal administration of this patch into diet-induced obese mice drastically improved glucose tolerance and insulin sensitivity and alleviated metabolic derangements associated with MAFLD. Furthermore, we uncovered a distinct molecular mechanism underlying the anti-obesity effects associated with the hepatic NLR family pyrin domain-containing 3 (NLRP3) inflammasome and autophagic clearance by the vera@CLCMP hydrogel patches.
Conclusion
The current study provides promising drug delivery platforms for long-term family treatment of chronic diseases, including obesity and metabolic dysfunctions.
Journal Article
Hepatocyte-Targeted Epicatechin Nanoparticles Promote Autophagy and Enhance Mitochondrial Function in Metabolic Dysfunction-Associated Steatotic Liver Disease
2025
Metabolic dysfunction-associated steatotic liver disease has limited treatment options, posing a serious global health challenge. Epicatechin (EC), a natural flavonoid, exhibits therapeutic potential; however, its clinical utility is hindered by its low solubility and limited bioavailability. Therefore, in this study, we developed liver-targeted EC-loaded galactosylated poly(lactic-co-glycolic acid)-polyethylene glycol nanoparticles (EC@PLGA-PEG-GAL NPs) with high therapeutic efficacy.
EC@PLGA-PEG-GAL NPs were synthesized, and their physicochemical properties, biocompatibility, and hepatocyte-targeted cellular uptake were characterized. The therapeutic efficacy of the NPs was assessed in high-fat diet (HFD)-fed mice, evaluating metabolic dysfunction and hepatic steatosis. Mechanistic studies were performed to investigate the effects on autophagic flux and mitochondrial function.
The EC@PLGA-PEG-GAL NPs exhibited improved EC solubility, sustained drug release, and low cytotoxicity. In HFD-fed mice, administration of EC@PLGA-PEG-GAL NPs significantly ameliorated hepatic steatosis, reduced insulin resistance, and alleviated metabolic dysfunction, without causing toxicity. Mechanistically, these NPs restored the autophagic flux by activating the AMP-activated protein kinase pathway and inhibiting mechanistic target of rapamycin complex 1 signaling, thereby enhancing ubiquitinated protein clearance. They also alleviated mitochondrial dysfunction by enhancing the membrane potential, reducing the reactive oxygen species levels, and promoting mitochondrial biogenesis.
Our findings highlight EC@PLGA-PEG-GAL NPs as promising liver-targeted nanotherapeutics simultaneously modulating autophagy and mitochondrial functions in metabolic dysfunction-associated steatotic liver disease.
Journal Article
TBK1 inhibitor amlexanox exerts anti-cancer effects against endometrial cancer by regulating AKT/NF-κB signaling
by
Lee, Sung Ki
,
Kim, Jeong Sig
,
Sung, Nak Song
in
Aminopyridines - pharmacology
,
Aminopyridines - therapeutic use
,
Animals
2025
Endometrial cancer, a common gynecological malignancy, poses significant clinical challenges, particularly in advanced or recurrent cases. TANK-binding kinase 1 (TBK1), a serine/threonine kinase, plays crucial roles in inflammation and immunity by activating nuclear factor (NF)-κB and interferon regulatory factor 3. However, its specific roles in endometrial cancer remain unknown. In this study, we aimed to investigate the anti-cancer effects and underlying mechanisms of amlexanox, a TBK1 inhibitor, against endometrial cancer. The main genetic mutations in TBK1 were found to be mRNA downregulation and missense mutations. Kaplan-Meier plotter analysis revealed that low TBK1 expression was associated with a good prognosis in patients with uterine corpus endometrial carcinoma (UCEC).
experiments demonstrated that
knockdown or amlexanox significantly inhibited the proliferation, cell cycle progression, and migration of endometrial cancer cells. Furthermore, the inhibitory effects of targeting TBK1 on cancer cell proliferation and migration were mediated by the protein kinase B (AKT)/NF-κB signaling pathway. Xenograft experiments revealed that both amlexanox treatment and
knockdown effectively suppressed the tumor growth. Overall, this study highlights the potent anti-cancer effects of amlexanox against endometrial cancer by modulating AKT/NF-κB signaling, thus providing a new avenue for the development of novel TBK1-targeting therapeutic strategies for UCEC.
Journal Article
Red-Emitting Latex Nanoparticles by Stepwise Entrapment of β-Diketonate Europium Complexes
2022
The core–shell structure of poly(St-co-MAA) nanoparticles containing β-diketonate Eu3+ complexes were synthesized by a step-wise process. The β-diketonate Eu3+ complexes of Eu (TFTB)2(MAA)P(Oct)3 [europium (III); 4,4,4-Trifluoro-1-(2-thienyl)-1,3-butanedione = TFTB; trioctylphosphine = (P(Oct)3); methacrylic acid = MAA] were incorporated to poly(St-co-MAA). The poly(St-co-MAA) has highly monodispersed with a size of 300 nm, and surface charges of the poly(St-co-MAA) are near to neutral. The narrow particle size distribution was due to the constant ionic strength of the polymerization medium. The activated carboxylic acid of poly(St-co-MAA) further chelated with europium complex and polymerize between acrylic groups of poly(St-co-MAA) and Eu(TFTB)2(MAA)P(Oct)3. The Em spectra of europium complexes consist of multiple bands of Em at 585, 597, 612 and 650 nm, which are assigned to 5D0→7FJ (J = 0–3) transitions of Eu3+, respectively. The maximum Em peak is at 621 nm, which indicates a strong red Em characteristic associated with the electric dipole 5D0→7F2 transition of Eu3+ complexes. The cell-specific fluorescence of Eu(TFTB)2(MAA)P(Oct)3@poly(St-co-MAA) indicated endocytosis of Eu(TFTB)2(MAA)P(Oct)3@poly(St-co-MAA). There are fewer early apoptotic, late apoptotic and necrotic cells in each sample compared with live cells, regardless of the culture period. Eu(TFTB)2(MAA)P(Oct)3@poly(St-co-MAA) synthesized in this work can be excited in the full UV range with a maximum Em at 619 nm. Moreover, these particles can substitute red luminescent organic dyes for intracellular trafficking and cellular imaging agents.
Journal Article
Magnetofluorescent Nanocomposite Comprised of Carboxymethyl Dextran Coated Superparamagnetic Iron Oxide Nanoparticles and β-Diketon Coordinated Europium Complexes
2019
Red emitting europium (III) complexes Eu(TFAAN)3(P(Oct)3)3 (TFAAN = 2-(4,4,4-Trifluoroacetoacetyl)naphthalene, P(Oct)3 = trioctylphosphine) chelated on carboxymethyl dextran coated superparamagnetic iron oxide nanoparticles (CMD-SPIONs) was synthesized and the step wise synthetic process was reported. All the excitation spectra of distinctive photoluminesces were originated from f-f transition of EuIII with a strong red emission. The emission peaks are due to the hypersensitive transition 5D0→7F2 at 621 nm and 5D0→7F1 at 597 nm, 5D0→7F0 at 584 nm. No significant change in PL properties due to addition of CMD-SPIONs was observed. The cytotoxic effects of different concentrations and incubation times of Eu(TFAAN)3(P(Oct)3)3 chelated CMD-SPIONs were evaluated in HEK293T and HepG2 cells using the WST assay. The results imply that Eu(TFAAN)3(P(Oct)3)3 chelated CMD-SPIONs are not affecting the cell viability without altering the apoptosis and necrosis in the range of 10 to 240 μg/mL concentrations.
Journal Article
Selenoprotein W ensures physiological bone remodeling by preventing hyperactivity of osteoclasts
2021
Selenoproteins containing selenium in the form of selenocysteine are critical for bone remodeling. However, their underlying mechanism of action is not fully understood. Herein, we report the identification of selenoprotein W (SELENOW) through large-scale mRNA profiling of receptor activator of nuclear factor (NF)-κΒ ligand (RANKL)-induced osteoclast differentiation, as a protein that is downregulated via RANKL/RANK/tumour necrosis factor receptor-associated factor 6/p38 signaling. RNA-sequencing analysis revealed that SELENOW regulates osteoclastogenic genes.
SELENOW
overexpression enhances osteoclastogenesis in vitro via nuclear translocation of NF-κB and nuclear factor of activated T-cells cytoplasmic 1 mediated by 14-3-3γ, whereas its deficiency suppresses osteoclast formation.
SELENOW
-deficient and
SELENOW
-overexpressing mice exhibit high bone mass phenotype and osteoporosis, respectively. Ectopic
SELENOW
expression stimulates cell-cell fusion critical for osteoclast maturation as well as bone resorption. Thus, RANKL-dependent repression of
SELENOW
regulates osteoclast differentiation and blocks osteoporosis caused by overactive osteoclasts. These findings demonstrate a biological link between selenium and bone metabolism.
Selenoproteins containing selenium have a variety of physiological functions including redox homeostasis and thyroid hormone metabolism. Here, the authors show that RANKL-dependent repression of selenoprotein W regulates cell fusion during osteoclast differentiation and bone remodelling in mice.
Journal Article
Analog reservoir computing via ferroelectric mixed phase boundary transistors
2024
Analog reservoir computing (ARC) systems have attracted attention owing to their efficiency in processing temporal information. However, the distinct functionalities of the system components pose challenges for hardware implementation. Herein, we report a fully integrated ARC system that leverages material versatility of the ferroelectric-to-mixed phase boundary (MPB) hafnium zirconium oxides integrated onto indium–gallium–zinc oxide thin-film transistors (TFTs). MPB-based TFTs (MPBTFTs) with nonlinear short-term memory characteristics are utilized for physical reservoirs and artificial neuron, while nonvolatile ferroelectric TFTs mimic synaptic behavior for readout networks. Furthermore, double-gate configuration of MPBTFTs enhances reservoir state differentiation and state expansion for physical reservoir and processes both excitatory and inhibitory pulses for neuronal functionality with minimal hardware burden. The seamless integration of ARC components on a single wafer executes complex real-world time-series predictions with a low normalized root mean squared error of 0.28. The material-device co-optimization proposed in this study paves the way for the development of area- and energy-efficient ARC systems.
Hardware implementation of analog reservoir computing is a challenge. The analog reservoir system in this work contains mixed phase boundary-based transistors with nonlinear short-term memory as physical reservoirs and artificial neuron, and nonvolatile ferroelectric transistors as readout networks.
Journal Article