• Molecules and Cells
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• v.41 no.7
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• pp.695-702
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• 2018

The inner ear is a complex sensory organ responsible for hearing and balance. Formation of the inner ear is dependent on tight regulation of spatial and temporal expression of genes that direct a series of developmental processes. Recently, epigenetic regulation has emerged as a crucial regulator of the development of various organs. However, what roles higher-order chromatin organization and its regulator molecules play in inner ear development are unclear. CCCTC-binding factor (CTCF) is a highly conserved 11-zinc finger protein that regulates the three-dimensional architecture of chromatin, and is involved in various gene regulation processes. To delineate the role of CTCF in inner ear development, the present study investigated inner ear-specific Ctcf knockout mouse embryos (Pax2-Cre; $Ctcf^{fl/fl}$). The loss of Ctcf resulted in multiple defects of inner ear development and severely compromised otic neurogenesis, which was partly due to a loss of Neurog1 expression. Furthermore, reduced Neurog1 gene expression by CTCF knockdown was found to be associated with changes in histone modification at the gene's promoter, as well as its upstream enhancer. The results of the present study demonstrate that CTCF plays an essential role in otic neurogenesis by modulating histone modification in the Neurog1 locus.

• Experimental and Molecular Medicine
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• v.50 no.11
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• pp.1.1-1.10
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• 2018

Bone marrow-derived mesenchymal stem cells (BMMSCs) are used extensively for cardiac repair and interact with immune cells in the damaged heart. Macrophages are known to be modulated by stem cells, and we hypothesized that priming macrophages with BMMSCs would enhance their therapeutic efficacy. Rat bone marrow-derived macrophages (BMDMs) were stimulated by lipopolysaccharide (LPS) with or without coculture with rat BMCs. In the LPS-stimulated BMDMs, induction of the inflammatory marker iNOS was attenuated, and the anti-inflammatory marker Arg1 was markedly upregulated by coculture with BMMSCs. Myocardial infarction (MI) was induced in rats. One group was injected with BMMSCs, and a second group was injected with MIX (a mixture of BMMSCs and BMDMs after coculture). The reduction in cardiac fibrosis was greater in the MIX group than in the BMC group. Cardiac function was improved in the BMMSC group and was substantially improved in the MIX group. Angiogenesis was better in the MIX group, and anti-inflammatory macrophages were more abundant in the MIX group than in the BMMSC group. In the BMMSCs, interferon regulatory factor 5 (IRF5) was exclusively induced by coculture with macrophages. IRF5 knockdown in BMMSCs failed to suppress inflammatory marker induction in the macrophages. In this study, we demonstrated the successful application of BMDMs primed with BMMSCs as an adjuvant to cell therapy for cardiac repair.

• BMB Reports
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• v.52 no.3
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• pp.208-213
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• 2019

Chemoresistance is the primary obstacle in the treatment of locally advanced and metastatic nasopharyngeal carcinoma (NPC). Recent evidence suggests that the transcription factor forkhead box M1 (FoxM1) is involved in chemoresistance. Our group previously confirmed that FoxM1 is overexpressed in NPC. In this study, we investigated the role of FoxM1 in cisplatin resistance of the cell lines 5-8F and HONE-1 and explored its possible mechanism. Our results showed that FoxM1 and NBS1 were both overexpressed in NPC tissues based on data from the GSE cohort (GSE12452). Then, we measured FoxM1 levels in NPC cells and found FoxM1 was overexpressed in NPC cell lines and could be stimulated by cisplatin. MTT and clonogenic assays, flow cytometry, ${\gamma}H2AX$ immunofluorescence, qRT-PCR, and western blotting revealed that downregulation of FoxM1 sensitized NPC cells to cisplatin and reduced the repair of cisplatin-induced DNA double-strand breaks via inhibition of the MRN (MRE11-RAD50-NBS1)-ATM axis, which might be related to the ability of FoxM1 to regulate NBS1. Subsequently, we demonstrated that enhanced sensitivity of FoxM1 knockdown cells could be reduced by overexpression of NBS1. Taken together, our data demonstrate that downregulation of FoxM1 could improve the sensitivity of NPC cells to cisplatin through inhibition of MRN-ATM-mediated DNA repair, which could be related to FoxM1-dependent regulation of NBS1.

• Journal of Microbiology and Biotechnology
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• v.32 no.7
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• pp.844-854
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• 2022

Helicobacter pylori, a group 1 carcinogen, colonizes the stomach and affects the development of stomach diseases. Progranulin (PGRN) is an autocrine growth factor that regulates multiple cellular processes and plays a tumorigenic role in many tissues. Nevertheless, the mechanism of action of PGRN in gastric cancer caused by H. pylori infection remains unclear. Here, we investigated the role of PGRN in cell cycle progression and the cell proliferation induced by H. pylori infection. We found that the increased PGRN was positively associated with CDK4 expression in gastric cancer tissue. PGRN was upregulated by H. pylori infection, thereby promoting cell proliferation, and that enhanced level of proliferation was reduced by PGRN inhibitor. CDK4, a target gene of PGRN, is a cyclin-dependent kinase that binds to cyclin D to promote cell cycle progression, which was upregulated by H. pylori infection. We also showed that knockdown of CDK4 reduced the higher cell cycle progression caused by upregulated PGRN. Moreover, when the PI3K/Akt signaling pathway (which is promoted by PGRN) was blocked, the upregulation of CDK4 mediated by PGRN was reduced. These results reveal the potential mechanism by which PGRN plays a major role through CDK4 in the pathological mechanism of H. pylori infection.

• Biomolecules & Therapeutics
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• v.31 no.3
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• pp.285-297
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• 2023

Alzheimer's disease (AD) is a neurodegenerative disease with progressive memory loss and the cognitive decline. AD is mainly caused by abnormal accumulation of misfolded amyloid β (Aβ), which leads to neurodegeneration via a number of possible mechanisms such as down-regulation of brain-derived neurotrophic factor-tropomyosin-related kinase B (BDNF-TRKB) signaling pathway. 7,8-Dihydroxyflavone (7,8-DHF), a TRKB agonist, has demonstrated potential to enhance BDNF-TRKB pathway in various neurodegenerative diseases. To expand the capacity of flavones as TRKB agonists, two natural flavones quercetin and apigenin, were evaluated. With tryptophan fluorescence quenching assay, we illustrated the direct interaction between quercetin/apigenin and TRKB extracellular domain. Employing Aβ folding reporter SH-SY5Y cells, we showed that quercetin and apigenin reduced Aβ-aggregation, oxidative stress, caspase-1 and acetylcholinesterase activities, as well as improved the neurite outgrowth. Treatments with quercetin and apigenin increased TRKB Tyr516 and Tyr817 and downstream cAMP-response-element binding protein (CREB) Ser133 to activate transcription of BDNF and BCL2 apoptosis regulator (BCL2), as well as reduced the expression of pro-apoptotic BCL2 associated X protein (BAX). Knockdown of TRKB counteracted the improvement of neurite outgrowth by quercetin and apigenin. Our results demonstrate that quercetin and apigenin are to work likely as a direct agonist on TRKB for their neuroprotective action, strengthening the therapeutic potential of quercetin and apigenin in treating AD.

• Journal of Life Science
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• v.21 no.11
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• pp.1625-1630
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• 2011

Heme oxygenase-1 (HO-1) is a stress-responsive protein that is known to regulate cellular functions such as cell proliferation, inflammation, and apoptosis. In this study, we investigated the role of NADPH oxidase on the expression of HO-1 in human liver hepatoma cell line HepG2. Diphenyleneiodonium (DPI), an NADPH oxidase inhibitor, markedly inhibited HO-1 expression and the nuclear translocation of transcription factor Nrf2 in cobalt protoporphyrin (CoPP) or hemin-treated HepG2 cells. Similarly, the knockdown of $p47^{phox}$, a cytosolic factor for NADPH oxidase activity, by siRNA inhibited the CoPP-induced expression of HO-1. In addition, GSHmee, an intracellular antioxidant, blocked the expression of HO-1 in CoPP-treated cells. Based on these results, we conclude that the blockage of NADPH oxidase with DPI or $p47^{phox}$ siRNA inhibits CoPP-induced HO-1 expression in HepG2 cells, and also suggest that the expression of HO-1 in CoPP-induced HepG2 cells is associated with increase of intracellular ROS by NADPH oxidase activity.

• Molecules and Cells
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• v.38 no.4
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• pp.327-335
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• 2015

Piperlongumine, a natural alkaloid isolated from the long pepper, selectively increases reactive oxygen species production and apoptotic cell death in cancer cells but not in normal cells. However, the molecular mechanism underlying piperlongumine-induced selective killing of cancer cells remains unclear. In the present study, we observed that human breast cancer MCF-7 cells are sensitive to piperlongumine-induced apoptosis relative to human MCF-10A breast epithelial cells. Interestingly, this opposing effect of piperlongumine appears to be mediated by heme oxygenase-1 (HO-1). Piperlongumine upregulated HO-1 expression through the activation of nuclear factor-erythroid-2-related factor-2 (Nrf2) signaling in both MCF-7 and MCF-10A cells. However, knockdown of HO-1 expression and pharmacological inhibition of its activity abolished the ability of piperlongumine to induce apoptosis in MCF-7 cells, whereas those promoted apoptosis in MCF-10A cells, indicating that HO-1 has anti-tumor functions in cancer cells but cytoprotective functions in normal cells. Moreover, it was found that piperlongumine-induced Nrf2 activation, HO-1 expression and cancer cell apoptosis are not dependent on the generation of reactive oxygen species. Instead, piperlongumine, which bears electrophilic ${\alpha},{\beta}$-unsaturated carbonyl groups, appears to inactivate Kelch-like ECH-associated protein-1 (Keap1) through thiol modification, thereby activating the Nrf2/HO-1 pathway and subsequently upregulating HO-1 expression, which accounts for piperlongumine-induced apoptosis in cancer cells. Taken together, these findings suggest that direct interaction of piperlongumine with Keap1 leads to the upregulation of Nrf2-mediated HO-1 expression, and HO-1 determines the differential response of breast normal cells and cancer cells to piperlongumine.

• Molecules and Cells
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• v.42 no.9
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• pp.672-685
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• 2019

Currently, liver transplantation is the only available remedy for patients with end-stage liver disease. Conservation of transplanted liver graft is the most important issue as it directly related to patient survival. Carbonyl reductase 1 (CBR1) protects cells against oxidative stress and cell death by inactivating cellular membrane-derived lipid aldehydes. Ischemia-reperfusion (I/R) injury during living-donor liver transplantation is known to form reactive oxygen species. Thus, the objective of this study was to investigate whether CBR1 transcription might be increased during liver I/R injury and whether such increase might protect liver against I/R injury. Our results revealed that transcription factor Nrf2 could induce CBR1 transcription in liver of mice during I/R. Pre-treatment with sulforaphane, an activator of Nrf2, increased CBR1 expression, decreased liver enzymes such as aspartate aminotransferase and alanine transaminase, and reduced I/R-related pathological changes. Using oxygen-glucose deprivation and recovery model of human normal liver cell line, it was found that oxidative stress markers and lipid peroxidation products were significantly lowered in cells overexpressing CBR1. Conversely, CBR1 knockdown cells expressed elevated levels of oxidative stress proteins compared to the parental cell line. We also observed that Nrf2 and CBR1 were overexpressed during liver transplantation in clinical samples. These results suggest that CBR1 expression during liver I/R injury is regulated by transcription factor Nrf2. In addition, CBR1 can reduce free radicals and prevent lipid peroxidation. Taken together, CBR1 induction might be a therapeutic strategy for relieving liver I/R injury during liver transplantation.

• Molecules and Cells
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• v.45 no.10
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• pp.718-728
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• 2022

Splicing factor B subunit 4 (SF3B4), a component of the U2-pre-mRNA spliceosomal complex, contributes to tumorigenesis in several types of tumors. However, the oncogenic potential of SF3B4 in lung cancer has not yet been determined. The in vivo expression profiles of SF3B4 in non-small cell lung cancer (NSCLC) from publicly available data revealed a significant increase in SF3B4 expression in tumor tissues compared to that in normal tissues. The impact of SF3B4 deletion on the growth of NSCLC cells was determined using a siRNA strategy in A549 lung adenocarcinoma cells. SF3B4 silencing resulted in marked retardation of the A549 cell proliferation, accompanied by the accumulation of cells at the G0/G1 phase and increased expression of p27, p21, and p53. Double knockdown of SF3B4 and p53 resulted in the restoration of p21 expression and partial recovery of cell proliferation, indicating that the p53/p21 axis is involved, at least in part, in the SF3B4-mediated regulation of A549 cell proliferation. We also provided ubiquitination factor E4B (UBE4B) is essential for p53 accumulation after SF3B4 depletion based on followings. First, co-immunoprecipitation showed that SF3B4 interacts with UBE4B. Furthermore, UBE4B levels were decreased by SF3B4 depletion. UBE4B depletion, in turn, reproduced the outcome of SF3B4 depletion, including reduction of polyubiquitinated p53 levels, subsequent induction of p53/p21 and p27, and proliferation retardation. Collectively, our findings indicate the important role of SF3B4 in the regulation of A549 cell proliferation through the UBE4B/p53/p21 axis and p27, implicating the therapeutic strategies for NSCLC targeting SF3B4 and UBE4B.

• Nutrition Research and Practice
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• v.18 no.1
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• pp.1-18
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• 2024

BACKGROUND/OBJECTIVES: Endoplasmic reticulum (ER) stress in adipose tissue causes an inflammatory response and leads to metabolic diseases. However, the association between vitamin D and adipose ER stress remains poorly understood. In this study, we investigated whether 1,25-dihydroxyvitamin D₃ (1,25(OH)₂D₃) alleviates ER stress in adipocytes. MATERIALS/METHODS: 3T3-L1 cells were treated with different concentrations (i.e., 10-100 nM) of 1,25(OH)₂D₃ after or during differentiation (i.e., on day 0-7, 3-7, or 7). They were then incubated with thapsigargin (TG, 500 nM) for an additional 24 h to induce ER stress. Next, we measured the mRNA and protein levels of genes involved in unfold protein response (UPR) and adipogenesis using real-time polymerase chain reaction and western blotting and quantified the secreted protein levels of pro-inflammatory cytokines. Finally, the mRNA levels of UPR pathway genes were measured in adipocytes transfected with siRNA-targeting Vdr. RESULTS: Treatment with 1,25(OH)₂D₃ during various stages of adipocyte differentiation significantly inhibited ER stress induced by TG. In fully differentiated 3T3-L1 adipocytes, 1,25(OH)₂D₃ treatment suppressed mRNA levels of Ddit3, sXbp1, and Atf4 and decreased the secretion of monocyte chemoattractant protein-1, interleukin-6, and tumor necrosis factor-α. However, downregulation of the mRNA levels of Ddit3, sXbp1, and Atf4 following 1,25(OH)₂D₃ administration was not observed in Vdr-knockdown adipocytes. In addition, exposure of 3T3-L1 preadipocytes to 1,25(OH)₂D₃ inhibited transcription of Ddit3, sXbp1, Atf4, Bip, and Atf6 and reduced the p-alpha subunit of translation initiation factor 2 (eIF2α)/eIF2α and p-protein kinase RNA-like ER kinase (PERK)/PERK protein ratios. Furthermore, 1,25(OH)₂D₃ treatment before adipocyte differentiation reduced adipogenesis and the mRNA levels of adipogenic genes. CONCLUSIONS: Our data suggest that 1,25(OH)₂D₃ prevents TG-induced ER stress and inflammatory responses in mature adipocytes by downregulating UPR signaling via binding with Vdr. In addition, the inhibition of adipogenesis by vitamin D may contribute to the reduction of ER stress in adipocytes.