Publications by authors named "Hyun Jik Lee"

Mesenchymal stem cell (MSC) transplantation offers significant potential for the treatment of diabetes mellitus (DM) and its complications. However, hyperglycemic conditions can induce senescence and dysfunction in both transplanted and resident MSCs, thereby limiting their therapeutic potential. Mitochondrial dysfunction and oxidative stress are key contributors to this process in MSCs exposed to hyperglycemia.

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Diabetic retinopathy (DR) is a leading cause of blindness in diabetic patients. Umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs) are emerging as a promising new drug for degenerative disease associated with diabetes. Recent studies have shown that high glucose-increased excessive calcium levels are a major risk factor for mitochondrial reactive oxygen species (mtROS) accumulation and apoptosis.

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Aβ: amyloid β; AD: Alzheimer disease; AMPK: 5' adenosine monophosphate-activated protein kinase; CTSB: cathepsin B; CTSD: cathepsin D; DM: diabetes mellitus; ESCRT: endosomal sorting complex required for transport; FBXO27: F-box protein 27; iPSC-NDs: induced pluripotent stem cell-derived neuronal differentiated cells; LAMP1: lysosomal-associated membrane protein 1; LMP: lysosomal membrane permeabilization; LRSAM1: leucine rich repeat and sterile alpha motif containing 1; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; MTORC1: mechanistic target of rapamycin kinase complex 1; p-MAPT/tau: phosphorylated microtubule associated protein tau; ROS: reactive oxygen species; STZ: streptozotocin; TFE3: transcription factor E3; TFEB: transcription factor EB; TRIM16: tripartite motif containing 16; UBE2QL1: ubiquitin conjugating enzyme E2 Q family like 1; VCP: valosin containing protein.

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Heavy alcohol consumption causes neuronal cell death and cognitive impairment. Neuronal cell death induced by ethanol may result from increased production of the sphingolipid metabolite ceramide. However, the molecular mechanisms of neuronal cell death caused by ethanol-induced ceramide production have not been elucidated.

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Background: Zinc (Zn) is an essential cofactor for physiological homeostasis in the body. Zn oxide (ZnO), an inorganic compound that supplies Zn, exists in various sizes, and its bioavailability may vary depending on the size . However, comparative studies on the nutritional effects of micro-sized ZnO (M-ZnO) and nano-sized ZnO (N-ZnO) supplementation on Zn deficiency (ZnD) animal models have not been reported.

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Background: Previous studies have presented evidence to support the significant association between red meat intake and colon cancer, suggesting that heme iron plays a key role in colon carcinogenesis. Epigallocatechin-3-gallate (EGCG), the major constituent of green tea, exhibits anti-oxidative and anti-cancer effects. However, the effect of EGCG on red meat-associated colon carcinogenesis is not well understood.

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Tumor necrosis factor-α (TNF-α) is an inflammatory cytokine involved in cell survival, apoptosis, and homeostasis. However, the regulatory effect of TNF-α on mesenchymal stem cell (MSC) redox regulation remains unknown. The process of delaying the senescence of MSCs and maintaining antioxidation mechanism is important in transplantation therapy to treat inflammatory diseases that result from restricted immunomodulatory effects of senescent MSCs.

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Exposure to maternal stress irreversibly impairs neurogenesis of offspring by inducing life-long effects on interaction between neurons and glia under raging differentiation process, culminating in cognitive and neuropsychiatric abnormalities in adulthood. We identified that prenatal exposure to stress-responsive hormone glucocorticoid impaired neurogenesis and induced abnormal behaviors in ICR mice. Then, we used human induced pluripotent stem cell (iPSC)-derived neural stem cell (NSC) to investigate how neurogenesis deficits occur.

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Background: Androgenetic alopecia (AGA) is a genetic disorder caused by dihydrotestosterone (DHT), accompanied by the senescence of androgen-sensitive dermal papilla cells (DPCs) located in the base of hair follicles. DHT causes DPC senescence in AGA through mitochondrial dysfunction. However, the mechanism of this pathogenesis remains unknown.

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Background: Retarded wound healing in patients with obesity contributes to a risk of complications associated with vascular insufficiency and oxidative stress. The high cholesterol levels of patients with obesity are associated with apoptosis of engrafted umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs). Melatonin contributes to the prevention of cholesterol accumulation in patients with obesity via a mechanism that is poorly understood.

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Stress-induced glucocorticoids disturb mitochondrial bioenergetics and dynamics; however, instead of being removed via mitophagy, the damaged mitochondria accumulate. Therefore, we investigate the role of glucocorticoids in mitophagy inhibition and subsequent synaptic defects in hippocampal neurons, SH-SY5Y cells, and ICR mice. First, we observe that glucocorticoids decrease both synaptic density and vesicle recycling due to suppressed mitophagy.

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Background: Neurodegeneration is a representative phenotype of patients with chronic alcoholism. Ethanol-induced calcium overload causes NOD-like receptor protein 3 (NLRP3) inflammasome formation and an imbalance in mitochondrial dynamics, closely associated with the pathogenesis of neurodegeneration. However, how calcium regulates this process in neuronal cells is poorly understood.

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Hyperglycemia in diabetes mellitus (DM) patients is a causative factor for amyloidogenesis and induces neuropathological changes, such as impaired neuronal integrity, neurodegeneration, and cognitive impairment. Regulation of mitochondrial calcium influx from the endoplasmic reticulum (ER) is considered a promising strategy for the prevention of mitochondrial ROS (mtROS) accumulation that occurs in the Alzheimer's disease (AD)-associated pathogenesis in DM patients. Among the metabolites of ellagitannins that are produced in the gut microbiome, urolithin A has received an increasing amount of attention as a novel candidate with anti-oxidative and neuroprotective effects in AD.

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The gut-brain axis is currently being studied as a therapeutic strategy for neurological diseases, especially Alzheimer's disease (AD). Obesity results in the gut microbiota dysbiosis, which includes butyrate-producing bacteria are reduced. Although sodium butyrate (NaB) has emerged as the potential therapeutic substance in AD, there is a lack of detailed results into what signaling pathways affect amyloidogenesis in AD induced by obesity.

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Background And Purpose: Although diabetes mellitus (DM) is an important risk factor for Alzheimer's disease (AD), the detailed mechanism(s) by which DM regulates amyloid β (Aβ) processing is still unclear. The longer residence time of amyloid precursor protein (APP) in endosomes is critical for Aβ production and DM is known to cause endosomal dysregulation. Here we have examined the effects of high glucose on APP-producing endosomes and related signaling pathways.

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Background: The prevalence and risk factors of low bone mineral density (BMD) in Asian patients newly diagnosed with inflammatory bowel disease (IBD) have not been fully suggested.

Aims: We aimed to examine the prevalence and risk factors of low BMD in young Korean patients newly diagnosed with IBD.

Methods: We prospectively enrolled 132 patients aged less than 50 years and newly diagnosed with IBD from six tertiary referral centers in Korea between November 2014 and April 2017.

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Background: Melatonin (5-methoxy-N-acetyltryptamine), a hormone produced in the pineal gland, has a variety of biological functions as an antioxidant, but a functional role of melatonin in the regulation of intestinal mucin (Muc) production during bacterial infection has yet to be described in detail. In this study, we investigate the effects of melatonin during Muc2 repression elicited by the Gram-negative bacterium V. vulnificus.

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Adaptation to hypoxia is essential for regulating the survival and functions of hypoxic cells; it is mainly mediated by the hypoxia-inducible factor 1 (HIF1). The alpha subunit of HIF1 (HIF1α) is a well-known regulatory component of HIF1, which is tightly controlled by various types of HIF1α-regulating processes. Previous research has shown that microtubule-regulated HIF1α nuclear translocation is a key factor for HIF1 activation under hypoxia.

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O-cyclic phytosphingosine-1-phosphate (cP1P) is a novel chemically synthesized sphingosine metabolite derived from phytosphingosine-1-phosphate. Although structurally similar to sphingosine-1-phosphate (S1P), its biological properties in stem cells remain to be reported. We investigated the effect of cP1P on the therapeutic potential of mesenchymal stem cells (MSCs) and their regulatory mechanism.

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Background/aims: Few studies have addressed the relationship between the occurrence of adverse events (AEs) in endoscopic retrograde cholangiopancreatography (ERCP) and hospital case volume or endoscopist's experience with inconsistent results. The aim of our study was to investigate the impact of hospital case volume and endoscopist's experience on the AEs associated with ERCP and to analyze patient- and procedure-related risk factors for post-ERCP AEs.

Methods: From January 2015 to December 2015, we prospectively enrolled patients with naïve papilla who underwent ERCP at six centers.

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Increasing antibiotic resistance has led to the development of new strategies to combat bacterial infection. Anti-virulence strategies that impair virulence of bacterial pathogens are one of the novel approaches with less selective pressure for developing resistance than traditional strategies that impede viability. In this study, a small molecule CM14 [N-(4-oxo-4H-thieno[3,4-c]chromen-3-yl)-3-phenylprop-2-ynamide] that inhibits the activity of HlyU, a transcriptional regulator essential for the virulence of the fulminating human pathogen Vibrio vulnificus, has been identified.

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Hypoxia-inducible factor 1 (HIF1) is a master transcription factor that induces the transcription of genes involved in the metabolism and behavior of stem cells. HIF1-mediated adaptation to hypoxia is required to maintain the pluripotency and survival of stem cells under hypoxic conditions. HIF1 activity is well known to be tightly controlled by the alpha subunit of HIF1 (HIF1).

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Sclerosing mesenteritis is a rare benign disease with a prevalence of 0.16-3.4% and is characterized by chronic nonspecific inflammation and extensive fibrosis in the adipose tissue of the mesentery although the exact pathogenesis is still elusive.

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Hypoxia inducible factor 1α (HIF1α) is a master regulator leading to metabolic adaptation, an essential physiological process to maintain the survival of stem cells under hypoxia. However, it is poorly understood how HIF1α translocates into the nucleus in stem cells under hypoxia. Here, we investigated the role of a motor adaptor protein Bicaudal D homolog 1 (BICD1) in dynein-mediated HIF1α nuclear translocation and the effect of BICD1 regulation on hypoxia adaptation and its therapeutic potential on human umbilical cord blood-derived mesenchymal stem cells (UCB-MSCs).

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Glucocorticoid, a major risk factor of Alzheimer's disease (AD), is widely known to promote microtubule dysfunction recognized as the early pathological feature that culminates in memory deficits. However, the exact glucocorticoid receptor (GR)-mediated mechanism of how glucocorticoid triggers microtubule destabilization and following intracellular transport deficits remains elusive. Therefore, we investigated the effect of glucocorticoid on microtubule instability and cognitive impairment using male ICR mice and human neuroblastoma SH-SY5Y cells.

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