Publications by authors named "Sung S Chung"

Four soluble factors-putrescine, glucosamine, nicotinamide, and signal transducer and activator of transcription 3 (STAT3) inhibitor BP-1-102-were shown to differentiate bone marrow mononucleated cells (BMNCs) into functional insulin-producing cells (IPCs) in vitro. Transplantation of these IPCs improved hyperglycemia in diabetic mice. However, the role of endogenous BMNC regeneration in this effect was unclear.

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Lipid droplets are not only lipid storage sites but also are closely related to lipid metabolism. Lipid droplet growth increases lipid storage capacity and suppresses lipolysis via lipase associated with the lipid droplet surface. The cell death-inducing DFF45-like effector (CIDE) family of proteins mediates lipid droplet fusion, which mainly contributes to lipid droplet growth.

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Bone marrow-derived stem cells are self-renewing and multipotent adult stem cells that differentiate into several types of cells. Here, we investigated a unique combination of 4 differentiation-inducing factors (DIFs), including putrescine (Put), glucosamine (GlcN), nicotinamide, and BP-1-102, to develop a differentiation method for inducing mature insulin-producing cells (IPCs) and apply this method to bone marrow mononucleated cells (BMNCs) isolated from mice. BMNCs, primed with the 4 soluble DIFs, were differentiated into functional IPCs.

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Background: Leptin is a 16-kDa fat-derived hormone with a primary role in controlling adipose tissue levels. Leptin increases fatty acid oxidation (FAO) acutely through adenosine monophosphate-activated protein kinase (AMPK) and on delay through the SUMO-specific protease 2 (SENP2)-peroxisome proliferator-activated receptor δ/γ (PPARδ/γ) pathway in skeletal muscle. Leptin also directly increases FAO and decreases lipogenesis in adipocytes; however, the mechanism behind these effects remains unknown.

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The adipose tissue is a key site regulating energy metabolism. One of the contributing factors behind this is browning of white adipose tissue (WAT). However, knowledge of the intracellular determinants of the browning process remains incomplete.

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Increasing evidence has shown that small ubiquitin-like modifier (SUMO) modification plays an important role in metabolic regulation. We previously demonstrated that SUMO-specific protease 2 (SENP2) is involved in lipid metabolism in skeletal muscle and adipogenesis. In this study, we investigated the function of SENP2 in pancreatic β cells by generating a β cell-specific knockout (Senp2-βKO) mouse model.

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Free fatty acids are converted to acyl-CoA by long-chain acyl-CoA synthetases (ACSLs) before entering into metabolic pathways for lipid biosynthesis or degradation. ACSL family members have highly conserved amino acid sequences except for their N-terminal regions. Several reports have shown that ACSL1, among the ACSLs, is located in mitochondria and mainly leads fatty acids to the β-oxidation pathway in various cell types.

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This study aimed to compare related factors of depressive symptoms among multicultural adolescents in South Korea. Cross-sectional data were collected from 1,325 students studying in ninth grade (mean age: 14.97 ± 0.

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Purpose: The current study was designed to describe risk and preventive factors related to cigarette smoking among adolescents in South Korea, Vietnam, and Thailand.

Design And Methods: A cross-sectional descriptive design was used. Student data were extracted from three national data sets, specifically the Global Youth Tobacco Survey from each country.

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Background: Chronic exposure to elevated levels of free fatty acids contributes to pancreatic β-cell dysfunction. Although it is well known that metformin induces cellular energy depletion and a concomitant activation of AMP-activated protein kinase (AMPK) through inhibition of the respiratory chain, previous studies have shown inconsistent results with regard to the action of metformin on pancreatic β-cells. We therefore examined the effects of metformin on pancreatic β-cells under lipotoxic stress.

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Article Synopsis
  • Researchers are exploring stem cell-derived insulin producing cells (IPCs) as a potential alternative to traditional islet transplantation for treating diabetes.
  • Current methods to differentiate stem cells into IPCs are lengthy and complex, but this study shows that bone marrow nucleated cells (BMNCs) can be converted into IPCs more efficiently using conditioned media from stressed pancreatic β-cells.
  • This method produced IPCs that expressed key insulin-producing markers, improved diabetic conditions in mice, and suggests that differentiating factors are contained within micro particles rather than being released as soluble substances.
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Background And Purpose: In addition to the central nervous system-mediated action, leptin also directly induces fatty acid oxidation in skeletal muscle. Rapid induction of FAO by leptin is mediated by the AMP-activated protein kinase (AMPK) pathway, but the mechanism of prolonged FAO by leptin was previously unknown. In an earlier study, we showed that free fatty acids increase transcription of small ubiquitin-like modifier (SUMO) specific protease 2 (SENP2) in skeletal muscle, and that SENP2 stimulates expression of FAO-associated enzymes by deSUMOylating peroxisome proliferator-activated receptors, PPARδ and PPARγ.

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Factors related to quality of life (QoL) were investigated using data from middle-aged and older Korean respondents to the 2006 and 2014 Korean Longitudinal Study of Ageing. Respondents' QoL score in 2014 (6.03 ± 1.

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Peroxisome proliferator-activated receptor γ (PPARγ) is a member of the nuclear receptor family and plays an important role in adipocyte differentiation, glucose homeostasis, and insulin sensitivity. Thiazolidinediones (TZDs), synthetic ligands of PPARγ, have been used for the treatment of diabetes mellitus for two decades. TZDs were expected to be amazing drugs not only for type 2 diabetes but also for metabolic syndrome and atherosclerotic vascular disease because they can reduce both insulin resistance and inflammation in experimental studies.

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The characteristics of and risk factors associated with binge drinking among South Korean and American adolescents were identified in this study. Data on adolescents in the 9th to 12th grades were extracted from two nationwide data sets: the Korea Youth Risk Behavior Web-based Survey System and the U.S.

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Background: A prolonged-release formulation of oxycodone/naloxone has been shown to be effective in European populations for the management of chronic moderate to severe pain. However, no clinical data exist for its use in Korean patients. The objective of this study was to assess efficacy and safety of prolonged-release oxycodone/naloxone in Korean patients for management of chronic moderate-to-severe pain.

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Objective: Autophagy is suppressed in skeletal muscle and the liver with insulin resistance induced by a high-fat diet. Autophagy is essential for maintaining mitochondrial function, and dysfunctional mitochondria are associated with insulin resistance. As carnitine treatment is well known to improve insulin resistance by promoting mitochondrial function, we investigated if carnitine affects autophagy in the skeletal muscle of a high-fat diet-induced rodent model of obesity.

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This study examined the demographics and health characteristics of depressive symptoms of Korean older adults. Data were from the 2014 survey of the Korean Longitudinal Study of Aging (KLoSA). Hierarchical logistic regression was conducted to identify risk factors of depressive symptoms.

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Background: Panax ginseng has glucose-lowering effects, some of which are associated with the improvement in insulin resistance in skeletal muscle. Because mitochondria play a pivotal role in the insulin resistance of skeletal muscle, we investigated the effects of the ginsenoside Rg3, one of the active components of P. ginseng, on mitochondrial function and biogenesis in C2C12 myotubes.

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Thyroid-stimulating hormone (TSH) receptor is expressed in extrathyroidal tissues such as hepatocytes, adipocytes, and skeletal muscle, which suggests a possible novel role of TSH in various metabolic processes in extrathyroidal tissues independent of thyroid hormones. We investigated whether TSH has any effects on glucose tolerance and insulin sensitivity in the skeletal muscle using diet-induced obesity (DIO) mouse models and rodent skeletal muscle cells. TSH improved glucose tolerance in DIO mice and this was associated with an improvement of skeletal muscle insulin sensitivity resulting from the increased expression of insulin receptor substrate (IRS)-1 protein and mRNA therein.

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Little attention has been paid to the individual, family, friends, and school profiles of depressed children during the transition from childhood to adolescence. This study aimed to describe the evolution of factors associated with depressive symptoms among elementary, middle, and high school students. This was a secondary analytic study using three datasets of a cohort of Korean children or adolescents.

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Peroxisome proliferator-activated receptor gamma (PPARγ) is a critical regulator of carbohydrate and lipid metabolism, adipocyte differentiation and inflammatory response. Post-translational modification of PPARγ and its degradation involve several pathways, including the ubiquitin-proteasome system. Here, we identified F-box only protein 9 (FBXO9) as an E3 ubiquitin ligase of PPARγ.

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Objective: We investigated the effect and regulatory mechanism of 2',4'-dihydroxy-6'-methoxy-3',5'-dimethylchalcone (DMC) isolated from Cleistocalyx operculatus on metabolic parameters in myotubes, adipocytes and an obese mouse model.

Materials And Methods: Myotubes and adipocytes were incubated with or without DMC. Glucose uptake, fatty acid oxidation, AMPK activation and adipocytes differentiation were investigated.

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Incretin-based therapy such as GLP-1 receptor agonists and DPP-4 inhibitors for type 2 diabetes mellitus is characterized by glucose-dependent insulin secretion and glucose-inhibited glucagon secretion. Recently, autophagy deficiency in islet β cells has been shown to contribute to the pathogenesis of type 2 diabetes mellitus however, with the role of incretin has not been established. To evaluate the role of autophagy in incretin effects, 8-week-old male β cell-specific Atg7 knockout (Atg7(Δβ cell)) mice and wild-type mice were administered vildagliptin for 12 weeks.

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Aims/hypothesis: Adipose tissue is a highly versatile system in which mitochondria in adipocytes undergo significant changes during active tissue remodelling. BCL2/adenovirus E1B 19 kDa protein-interacting protein 3 (BNIP3) is a mitochondrial protein and a known mitochondrial quality regulator. In this study, we investigated the role of BNIP3 in adipocytes, specifically under conditions of peroxisome proliferator-activated receptor-γ (PPARγ)-induced adipose tissue remodelling.

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