Expression of Fibroblast Growth Factor 21 and β-Klotho Regulates Hepatic Fibrosis through the Nuclear Factor-κB and c-Jun N-Terminal Kinase Pathways

( Kyong Joo Lee ),( Yoon Ok Jang ),( Seung-kuy Cha ),( Moon Young Kim ),( Kyu-sang Park ),( Young Woo Eom ),( Soon Koo Baik ) 대한간학회 2018 Gut and Liver Vol.12 No.4

Background/Aims: Fibroblast growth factor (FGF) 21 is associated with hepatic inflammation and fibrosis. However, little is known regarding the effects of inflammation and fibrosis on the β-Klotho and FGF21 pathway in the liver. Methods: Enrolled patients had biopsy-confirmed viral or alcoholic hepatitis. FGF19, FGF21 and β-Klotho levels were evaluated using enzyme-linked immunosorbent assay, real-time polymerase chain reaction, and Western blotting. Furthermore, we explored the underlying mechanisms for this process by evaluating nuclear factor-κB (NF-κB) and c-Jun N-terminal kinase (JNK) pathway involvement in Huh-7 cells. Results: We observed that the FGF19 and FGF21 serum and mRNA levels in the biopsied liver tissue gradually increased and were correlated with fibrosis stage. Inflammatory markers (interleukin 1β [IL-1β], IL-6, and tumor necrosis factor-α) were positively correlated, while β-Klotho expression was negatively correlated with the degree of fibrosis. In Huh-7 cells, IL-1β increased FGF21 levels and decreased β-Klotho levels. NF-κB and JNK inhibitors abolished the effect of IL-1β on both FGF21 and β-Klotho expression. FGF21 protected IL-1β-induced growth retardation in Huh-7 cells. Conclusions: These results indicate that the inflammatory response during fibrogenesis increases FGF21 levels and suppresses β-Klotho via the NF-κB and JNK pathway. In addition, FGF21 likely protects hepatocytes from hepatic inflammation and fibrosis. (Gut Liver 2018;12:449-456)

Secondary Focal Segmental Glomerulosclerosis: From Podocyte Injury to Glomerulosclerosis

Kim, Jae Seok,Han, Byoung Geun,Choi, Seung Ok,Cha, Seung-Kuy Hindawi Publishing Corporation 2016 BioMed research international Vol.2016 No.-

<P>Focal segmental glomerulosclerosis (FSGS) is a common cause of proteinuria and nephrotic syndrome leading to end stage renal disease (ESRD). There are two types of FSGS, primary (idiopathic) and secondary forms. Secondary FSGS shows less severe clinical features compared to those of the primary one. However, secondary FSGS has an important clinical significance because a variety of renal diseases progress to ESRD thorough the form of secondary FSGS. The defining feature of FSGS is proteinuria. The key event of FSGS is podocyte injury which is caused by multiple factors. Unanswered questions about how these factors act on podocytes to cause secondary FSGS are various and ill-defined. In this review, we provide brief overview and new insights into FSGS, podocyte injury, and their potential linkage suggesting clues to answer for treatment of the disease.</P>

Essential Role of Mitochondrial Ca²⁺ Uniporter in the Generation of Mitochondrial pH Gradient and Metabolism-Secretion Coupling in Insulin-releasing Cells

Quan, Xianglan,Nguyen, Tuyet Thi,Choi, Seong-Kyung,Xu, Shanhua,Das, Ranjan,Cha, Seung-Kuy,Kim, Nari,Han, Jin,Wiederkehr, Andreas,Wollheim, Claes B.,Park, Kyu-Sang American Society for Biochemistry and Molecular Bi 2015 The Journal of biological chemistry Vol.290 No.7

<P>In pancreatic β-cells, ATP acts as a signaling molecule initiating plasma membrane electrical activity linked to Ca<SUP>2+</SUP> influx, which triggers insulin exocytosis. The mitochondrial Ca<SUP>2+</SUP> uniporter (MCU) mediates Ca<SUP>2+</SUP> uptake into the organelle, where energy metabolism is further stimulated for sustained second phase insulin secretion. Here, we have studied the contribution of the MCU to the regulation of oxidative phosphorylation and metabolism-secretion coupling in intact and permeabilized clonal β-cells as well as rat pancreatic islets. Knockdown of MCU with siRNA transfection blunted matrix Ca<SUP>2+</SUP> rises, decreased nutrient-stimulated ATP production as well as insulin secretion. Furthermore, MCU knockdown lowered the expression of respiratory chain complexes, mitochondrial metabolic activity, and oxygen consumption. The pH gradient formed across the inner mitochondrial membrane following nutrient stimulation was markedly lowered in MCU-silenced cells. In contrast, nutrient-induced hyperpolarization of the electrical gradient was not altered. In permeabilized cells, knockdown of MCU ablated matrix acidification in response to extramitochondrial Ca<SUP>2+</SUP>. Suppression of the putative Ca<SUP>2+</SUP>/H<SUP>+</SUP> antiporter leucine zipper-EF hand-containing transmembrane protein 1 (LETM1) also abolished Ca<SUP>2+</SUP>-induced matrix acidification. These results demonstrate that MCU-mediated Ca<SUP>2+</SUP> uptake is essential to establish a nutrient-induced mitochondrial pH gradient which is critical for sustained ATP synthesis and metabolism-secretion coupling in insulin-releasing cells.</P>

Biological Role of Anti-aging Protein Klotho

Kim, Ji-Hee,Hwang, Kyu-Hee,Park, Kyu-Sang,Kong, In Deok,Cha, Seung-Kuy Yonsei University Wonju College of Medicine 2015 Journal of lifestyle medicine Vol.5 No.1

<P>Klotho-deficient mice have accelerated aging phenotypes, whereas overexpression of Klotho in mice extends lifespan. Klotho is an anti-aging single-pass membrane protein predominantly produced in the kidney, with shedding of the amino-terminal extracellular domain into the systemic circulation. Circulating levels of soluble Klotho decrease with age, and the <I>klotho</I> gene is associated with increased risk of age-related diseases. The three forms of Klotho protein have distinct functions. Membrane Klotho forms a complex with fibroblast growth factor (FGF) receptors, functions as an obligatory co-receptor for FGF23, which is involved in aging and the development of chronic diseases via regulation of P<I><SUB>i</SUB></I> and vitamin D metabolism. Secreted Klotho functions as a humoral factor with pleiotropic activities including regulation of oxidative stress, growth factor signaling, and ion homeostasis. Secreted Klotho is also involved in organ protection. The intracellular form of Klotho suppresses inflammation-mediated cellular senescence and mineral metabolism. Herein we provide a brief overview of the structure and function and recent research about Klotho.</P>

Effects of Oxidative-type Abdominal Curl Training on Body Composition in 30s' Men

Yong-Seok Jee(지용석),Jae-Hyeng Im(임재형),Cha-Yong Kim(김차용),Tae-Kuy Choi(최태규),Kwang-Yeon Hwang(황광연),Hyun Lee(이현),Eun-Joo Jun(전은주),Hyun-Doo Seo(서현두),Seung-Gun Im(임승건),Dong-Jin Kim(김동진),Hyun-Min Lee(이현민),Pil 한국코칭능력개발원 2004 코칭능력개발지 Vol.6 No.3

Synergistic Effects of Simvastatin and Bone Marrow-Derived Mesenchymal Stem Cells on Hepatic Fibrosis

( Yoon Ok Jang ),( Soon Koo Baik ),( Mee-yon Cho ),( Kyu-sang Park ),( Seung-kuy Cha ),( Sung Hoon Kim ),( Moon Young Kim ) 대한간학회 2017 춘·추계 학술대회 (KASL) Vol.2017 No.1

Aims: The beneficial effects of simvastatin on fibrosis in various organs have been reported. In addition, bone marrow-derived mesenchymal stem cells (MSCs) have been suggested as an effective therapy for hepatic fibrosis and cirrhosis. Recent evidence suggests that pharmacological treatment devoted to regulating stem cell function is a potential new therapeutic strategy, which is drawing nearer to clinical practice. The aim of this study was to determine whether the combination treatment of simvastatin plus MSCs (Sim-MSCs) could have a synergistic effect on hepatic fibrosis in a thioacetamide (TAA)-induced cirrhotic rat model. Methods: Hepatic fibrosis was induced in Sprague-Dawley rats by intraperitoneal injection of TAA (300 mg/kg body weight) twice a week for 12 weeks. Animals were randomly allocated into four groups (each group, n = 10) as follows: group I (G1, sham group); group II (G2, untreated cirrhotic group), which received the TAA injections; group III (G3, Simvastatin treated group), which received both the TAA injections and the simvastatin treatment; and group IV (G4, Simvastatin plus MSCs treated group), which received both the TAA injections and the Sim-MSCs treatment. G3 and G4 were given simvastatin at 10 mg·kg-1·day-1 via drinking water for 5 weeks. The BM-MSCs were injected directly into the right lobe of the liver at 6 and 8 weeks during the 12-week course of TAA administration. After 12 weeks, the effect of simvastatin and BM-MSCs on hepatic fibrosis was analyzed histomorphologically using the Laennec fibrosis scoring system, and the collagen proportionate area was quantified. Cirrhosis-related factors, such as transforming growth factor β1 (TGF-β 1), type 1 collagen (collagen-1), α-smooth muscle actin (α-SMA), and P-Smad3/Smad3 expression levels, were evaluated using real-time polymerase chain reaction and western blot assays. Results: Cirrhotic livers from rats treated with Sim-MSCs exhibited histological improvement compared to those treated with simvastatin alone. Sim-MSCs combination treatment reduced hepatic collagen distribution, lowered the hydroxyproline content, and rescued liver function impairment in rats with TAA-induced cirrhosis. These protective effects were more potent with Sim-MSCs than with simvastatin alone. The upregulation of collagen-1, α-SMA, TGF-β1, and Smad3 phosphorylation in cirrhotic livers was prevented by administration of Sim-MSCs. The Sim-MSCs combination treatment exerted strong protective effects against hepatic fibrosis by suppressing TGF-β/Smad signaling. Conclusions: Simvastatin could act synergistically with MSCs as an efficient therapeutic approach for intractable cirrhosis.

Switching-on of serotonergic calcium signaling in activated hepatic stellate cells.

Park, Kyu-Sang,Sin, Pyo-Jin,Lee, Dong Hyeon,Cha, Seung-Kuy,Kim, Min-Jeong,Kim, Na-Hyun,Baik, Soon-Koo,Jeong, Seong-Woo,Kong, In Deok WJG Press 2011 World journal of gastroenterology Vol.17 No.2

<P>To investigate serotonergic Ca²+ signaling and the expression of 5-hydroxytryptamine (5-HT) receptors, as well as Ca²+ transporting proteins, in hepatic stellate cells (HSCs).</P>

Mitochondrial Ca²⁺ Uptake Relieves Palmitate-Induced Cytosolic Ca²⁺ Overload in MIN6 Cells

Ly, Luong Dai,Ly, Dat Da,Nguyen, Nhung Thi,Kim, Ji-Hee,Yoo, Heesuk,Chung, Jongkyeong,Lee, Myung-Shik,Cha, Seung-Kuy,Park, Kyu-Sang Korean Society for Molecular and Cellular Biology 2020 Molecules and cells Vol.43 No.1

Saturated fatty acids contribute to β-cell dysfunction in the onset of type 2 diabetes mellitus. Cellular responses to lipotoxicity include oxidative stress, endoplasmic reticulum (ER) stress, and blockage of autophagy. Palmitate induces ER Ca²⁺ depletion followed by notable store-operated Ca²⁺ entry. Subsequent elevation of cytosolic Ca²⁺ can activate undesirable signaling pathways culminating in cell death. Mitochondrial Ca²⁺ uniporter (MCU) is the major route for Ca²⁺ uptake into the matrix and couples metabolism with insulin secretion. However, it has been unclear whether mitochondrial Ca²⁺ uptake plays a protective role or contributes to lipotoxicity. Here, we observed palmitate upregulated MCU protein expression in a mouse clonal β-cell, MIN6, under normal glucose, but not high glucose medium. Palmitate elevated baseline cytosolic Ca²⁺ concentration ([Ca²⁺]_i) and reduced depolarization-triggered Ca²⁺ influx likely due to the inactivation of voltage-gated Ca²⁺ channels (VGCCs). Targeted reduction of MCU expression using RNA interference abolished mitochondrial superoxide production but exacerbated palmitate-induced [Ca²⁺]_i overload. Consequently, MCU knockdown aggravated blockage of autophagic degradation. In contrast, co-treatment with verapamil, a VGCC inhibitor, prevented palmitate-induced basal [Ca²⁺]_i elevation and defective [Ca²⁺]_i transients. Extracellular Ca²⁺ chelation as well as VGCC inhibitors effectively rescued autophagy defects and cytotoxicity. These observations suggest enhanced mitochondrial Ca²⁺ uptake via MCU upregulation is a mechanism by which pancreatic β-cells are able to alleviate cytosolic Ca²⁺ overload and its detrimental consequences.

Upregulation of NADPH Oxidase 4 and Oxidative Stress via TGF-β-ERK-mTOR Pathway in Transdifferentiation of Mouse Hepatic Stellate Cells

( Soo Jin Kim ),( Kyu Hee Hwang ),( Ji Hee Kim ),( Moon Young Kim ),( Soon Koo Baik ),( Seung Kuy Cha ),( Ranjan Das ),( Kyu Sang Park ) 대한간학회 2016 춘·추계 학술대회 (KASL) Vol.2016 No.1

Aims: Liver cirrhosis results from chronic hepatotoxic injuries, characterized by fibrotic changes with accumulation of extracellular matrix. The principal mediator of fibrosis is known as transdifferentiation of hepatic stellate cells (HSCs) into myofibroblasts. Oxidative stress is involved in the initiation of this process, however, molecular mechanism of reactive oxygen species (ROS) generation from HSCs has not been clearly identified. Methods: Liver fibrosis in mice was developed by thioacetamide (TAA) administration. Mechanistic studies were conducted using primary HSCs isolated and purified from Balb/C mice of 20 weeks of age. RNA and protein levels were quantified by real-time PCR and western blotting, respectively. ROS generation was measured by a confocal imaging system with DCF fluorescence dye. Results: We observed consistent and marked upregulation of NADPH oxidase 4 (NOX4) along with α-smooth muscle actin (α-SMA) and plasminogen activator inhibitor 1 (PAI-1) in the process of hepatic fibrosis development. Increased expression of TGF-β and activation of its downstream signaling cascades including extracellular signal- regulated kinases (ERK) and mammalian target of rapamycin (mTOR) were prominent at the early period of TAA treatment. In primary mouse HSCs, upregulation of α-SMA, PAI-1 and vimentin were evident during culture. We also observed time-dependent increase in TGF-β and NOX4 protein levels as well as activation of ERK1/2 and mTOR pathways. Consistent with NOX4 upregulation, cytosolic ROS was elevated during myofibrotic changes in primary HSCs, which was attenuated by SB431542 (TGF-β receptor blocker), PD184352 (ERK inhibitor) or rapamycin (mTORC1 inhibitor). Conclusions: We suggest that oxidative stress during transdifferentiation of HSCs may be originated from increased NOX4 protein triggered by TGF-β-ERK-mTOR axis, inhibition of which could be an effective therapeutic target to prevent the progression of liver cirrhosis.

Transforming Growth Factor β1-induced Apoptosis in Podocytes via the Extracellular Signal-regulated Kinase-Mammalian Target of Rapamycin Complex 1-NADPH Oxidase 4 Axis

Das, Ranjan,Xu, Shanhua,Nguyen, Tuyet Thi,Quan, Xianglan,Choi, Seong-Kyung,Kim, Soo-Jin,Lee, Eun Young,Cha, Seung-Kuy,Park, Kyu-Sang American Society for Biochemistry and Molecular Bi 2015 The Journal of biological chemistry Vol.290 No.52

<P>TGF-β is a pleiotropic cytokine that accumulates during kidney injuries, resulting in various renal diseases. We have reported previously that TGF-β1 induces the selective up-regulation of mitochondrial Nox4, playing critical roles in podocyte apoptosis. Here we investigated the regulatory mechanism of Nox4 up-regulation by mTORC1 activation on TGF-β1-induced apoptosis in immortalized podocytes. TGF-β1 treatment markedly increased the phosphorylation of mammalian target of rapamycin (mTOR) and its downstream targets p70S6K and 4EBP1. Blocking TGF-β receptor I with SB431542 completely blunted the phosphorylation of mTOR, p70S6K, and 4EBP1. Transient adenoviral overexpression of mTOR-WT and constitutively active mTORΔ augmented TGF-β1-treated Nox4 expression, reactive oxygen species (ROS) generation, and apoptosis, whereas mTOR kinase-dead suppressed the above changes. In addition, knockdown of mTOR mimicked the effect of mTOR-KD. Inhibition of mTORC1 by low-dose rapamycin or knockdown of p70S6K protected podocytes through attenuation of Nox4 expression and subsequent oxidative stress-induced apoptosis by TGF-β1. Pharmacological inhibition of the MEK-ERK cascade, but not the PI3K-Akt-TSC2 pathway, abolished TGF-β1-induced mTOR activation. Inhibition of either ERK1/2 or mTORC1 did not reduce the TGF-β1-stimulated increase in Nox4 mRNA level but significantly inhibited total Nox4 expression, ROS generation, and apoptosis induced by TGF-β1. Moreover, double knockdown of Smad2 and 3 or only Smad4 completely suppressed TGF-β1-induced ERK1/2-mTORactivation. Our data suggest that TGF-β1 increases translation of Nox4 through the Smad-ERK1/2-mTORC1 axis, which is independent of transcriptional regulation. Activation of this pathway plays a crucial role in ROS generation and mitochondrial dysfunction, leading to podocyte apoptosis. Therefore, inhibition of the ERK1/2-mTORC1 pathway could be a potential therapeutic and preventive target in proteinuric and chronic kidney diseases.</P>