Jung Min Ryu

Seoul National University, Sŏul, Seoul, South Korea

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Publications (33)105.4 Total impact

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    ABSTRACT: Netrin-1 (Ntn-1) is a potent inducer of neuronal cell migration; however its molecular mechanism which guides the migratory behavior of stem cells has not been characterized. In the present study, we investigate the role of Ntn-1 in promoting the motility of human umbilical cord blood derived mesenchymal stem cells (UCB-MSCs) and its related signaling pathways. Ntn-1 (50 ng/mL) significantly increased UCB-MSCs motility, which was inhibited by blocking antibodies for deleted in colorectal cancer (DCC) and integrin (IN) α6β4. Ntn-1 in DCC stimulated PKCα activation, but not PKCε, PKCθ, and PKCζ, while Ntn-1 in INα6β4 induced the phosphorylation of focal adhesion kinase (FAK) and Fyn. Notably, Ntn-1 induced phosphorylation of extracellular signal-regulated kinases (ERK), c-Jun N-terminal kinases (JNK), and nuclear factor kappa-B (NF-κB), but they were concurrently down-regulated by blocking the activities of PKCα, FAK, and Fyn. Ntn-1 uniquely increased the MMP-12 expression of all the matrix metalloproteinase (MMP) isoforms present in UCB-MSCs, though this was significantly blocked by a NF-κB inhibitor. Finally, Ntn-1 induced the MMP-12-dependent degradation of E-cadherin (E-cad), while Ntn-1 abrogated the interaction between E-cad and p120-catenin. In addition, Ntn-1 has the ability to stimulate cytoskeletal reorganization-related proteins, such as Cdc42, Rac1, Profilin-1, Cofilin-1, α-Actinin-4, and filamentous actin (F-actin) in UCB-MSCs. These results demonstrate that Ntn-1 induces MMP-12-dependent E-cad degradation via the distinct activation of PKCα and FAK/Fyn, which is necessary to govern the activation of ERK, JNK, and NF-κB in promoting UCB-MSCs motility.
    Stem cells and development 04/2014; · 4.15 Impact Factor
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    ABSTRACT: We aimed to study the relationship between glucosamine and FoxO1/Notch in gluconeogenesis and maintenance of mouse embryonic stem cell (mESC) self-renewal. Glucosamine (GlcN) increased glucose production and gluconeogenic enzymes (G6Pase and PEPCK) expression. GlcN also increased the percentage of cells in S phase, the protein expression of cell cycle regulatory proteins, and number of cells, which were blocked by 3-mercaptopicolinic acid (gluconeogenesis inhibitor) or glucose transporter (GLUT) 1 neutralizing antibody. GlcN increased the O-GlcNAc transferase (OGT)-dependent protein O-GlcNAc level. Moreover, inhibition of OGT (by ST045849) decreased glucose production. GlcN enhanced the expression of OGT-dependent O-GlcNAcylated Notch1 and then increased the translocation of cleaved Notch1 to the nucleus. Moreover, GlcN stimulated the translocation of O-GlcNAcylated FoxO1 to the nucleus. GlcN increased the binding between cleaved Notch1 and FoxO1 with CSL, a transcription factor, which was blocked by L-685,458 (γ-secretase inhibitor) or ST045849, respectively. Simultaneous blockage of cleaved Notch1 and FoxO1 also decreased the expression of G6Pase and PEPCK more significantly than that by inhibition of cleaved Notch1 alone or FoxO1 alone. In addition, GlcN maintained the undifferentiation status while depletion of Notch1 and FoxO1 for 3 days decreased Oct4 and SSEA-1 expression and alkaline phosphatase activity or increased the mRNA expression of GATA4, Tbx5, Cdx2, and Fgf5. In conclusion, GlcN-induced OGT activation mediated glucose production through cleaved Notch1 and FoxO1, which contributed to the regulation of maintenance of self-renewal in mESCs.
    Stem cells and development 04/2014; · 4.15 Impact Factor
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    ABSTRACT: Background and PurposeReactive oxygen species (ROS) are potent regulator of stem cell behavior; however, their physiological significance as regards the matrix metalloproteinase (MMP) regulation of the motility of human umbilical cord blood derived mesenchymal stem cells (UCB-MSCs) has not been characterized. In the present study, we investigate the role of hydrogen peroxide (H2O2) in promoting UCB-MSCs motility and its related signaling pathways.Experimental ApproachThe regulatory effects of H2O2 on the activation of PKC, MAPKs, NF-κB, and β-catenin were determined. The expressions of MMP and ECM proteins were examined. Pharmacological inhibitors and gene specific siRNA were used to identify the signaling pathways of H2O2 that affect UCB-MSCs motility. An experimental skin wound healing model was used to confirm the functional role of UCB-MSCs treated with H2O2 in ICR mice.Key ResultsH2O2 induced UCB-MSCs motility by activating PKCα via a calcium influx mechanism. H2O2 activated ERK and p38 MAPK that are responsible for the distinct activation of transcription factors NF-κB and β-catenin. UCB-MSCs expressed eight MMP genes, but only MMP-12 expression is uniquely regulated by NF-κB and β-catenin activation. H2O2 induced the MMP-12-dependent degradation of collagen 5 (COL-5) and fibronectin (FN) as it relates to UCB-MSCs motility. Finally, topical transplantation of UCB-MSCs treated with H2O2 enhanced skin-wound healing in mice.Conclusions and ImplicationsH2O2 stimulated UCB-MSCs motility by increasing MMP-12-dependent degradation of COL-5 and FN through the activation of NF-κB and GSK-3β/β-catenin, which is critical for providing a suitable microenvironment for MSC transplantation and re-epithelialization of mouse skin wounds.
    British Journal of Pharmacology 03/2014; · 5.07 Impact Factor
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    ABSTRACT: Although recent findings showed that the bioactive lipid metabolites can regulate the ES cell functions, the physiological relevance of interaction between sphingosine-1-phosphate (S1P) and Flk-1 and its related signaling molecules are not yet clear in ES cell proliferation. In the present study, S1P1-5 receptors were expressed in mouse ES cells and S1P increased S1P1-3 receptor expression level. S1P treatment stimulated the cellular proliferation in S1P1/3-dependent manner, located in lipid rafts. In response to S1P, β-arrestin was recruited to S1P1/3 receptor and c-Src was activated. S1P also increased the binding of S1P1/3 receptor with Flk-1. Similar to responses for VEGF, S1P increased Flk-1 phosphorylation, which was blocked by β-arrestin siRNA, and PP2, but not by VEGF-A164 antibody or VEGF siRNA. In addition, S1P induced VEGF expression and VEGFR2 kinase inhibitor (SU1498) blocked the S1P-induced cellular proliferation. However, VEGF-A164 antibody or VEGF siRNA partially blocked S1P-induced cellular proliferation, suggesting that both VEGF-dependent Flk-1 activation and VEGF-independent Flk-1 activation are involved in S1P-induced ES cell proliferation. S1P and VEGF-induced phosphorylation of ERK and JNK were blocked by pretreatment with SU1498. Moreover, inhibition of ERK and JNK blocked S1P-induced cellular proliferation. In conclusion, S1P-elicited transactivation of Flk-1 mediated by S1P1/3-dependent β-arrestin/c-Src pathways stimulated mouse ES cell proliferation.
    Stem Cell Research 09/2013; 12(1):69-85. · 4.47 Impact Factor
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    ABSTRACT: Quorum sensing is a cell-to-cell communication system known to control many bacterial processes. In the present study, the functions of quorum sensing in the pathogenesis of Vibrio vulnificus, a foodborne pathogen, were assessed by evaluating the virulence of a mutant deficient in SmcR, a quorum-sensing regulator and homologue of LuxR. When biofilms were used as an inoculum, the smcR mutant was impaired in virulence and colonization capacity in the infection of mice. The lack of SmcR also resulted in decreased histopathological damage in mouse jejunum tissue. These results indicated that SmcR is essential for V. vulnificus pathogenesis. Moreover, the smcR mutant exhibited significantly reduced biofilm detachment. Upon exposure to INT-407 host cells, the wild type, but not the smcR mutant, revealed accelerated biofilm detachment. The INT-407 cells increased smcR expression by activating the expression of LuxS, an autoinducer-2 synthase, indicating that host cells manipulate the cellular level of SmcR through the quorum-sensing signaling of V. vulnificus. A whole genome microarray analysis revealed that the genes primarily involved in biofilm detachment and formation are up- and down-regulated by SmcR, respectively. Among the SmcR-regulated genes, vvpE encoding an elastolytic protease was the most up-regulated and the purified VvpE appeared to dissolve established biofilms directly in a concentration-dependent manner in vitro. These results suggest that the host cell-induced SmcR enhances the detachment of V. vulnificus biofilms entering the host intestine and thereby may promote the dispersal of the pathogen to new colonization loci, which is crucial for pathogenesis.
    Infection and immunity 07/2013; · 4.21 Impact Factor
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    ABSTRACT: Delphinidin, gallic acid, betulinic acid, and ursolic acid, which are bio-active ingredients in a variety of fruits, vegetables, and herbs, have potent antioxidant activity and various biological activities. However, it is not clear whether these bio-active ingredients can significantly contribute to the protection of embryonic stem (ES) cells from hypoxia-induced apoptosis. In the present study, hypoxia-induced ES cells apoptosis with time, which were abrogated by pretreatment with all ingredients. Hypoxia-induced ROS generation was blocked by pretreatment with all ingredients in a dose-dependent manner, with the maximum ROS scavenging effect observed for delphinidin. Hypoxia increased phosphorylation of JNK and NF-κB were blocked by pretreatment of delphinidin as well as NAC. Hypoxia decreased phosphorylation of Akt(thr308) and (ser473); these decreases were reversed by pretreatment with delphinidin or NAC. However, Akt inhibition did not affect NF-κB phosphorylation. Delphinidin attenuated the hypoxia-induced increase in Bax, cleaved caspase-9, cleaved caspase-3, and decrease in Bcl-2, which were diminished by pretreatment of Akt inhibitor. Hypoxia induced Bax translocation from the cytosol to mitochondria. Furthermore, hypoxia induced mitochondria membrane potential loss and cytochrome c release in cytosol, which were blocked by delphinidin pretreatment. Hypoxia induced cleavage of procaspase-9 and procaspase-3 which were blocked by delphinidin or SP600125, but Akt inhibitor abolished the protection effect of delphinidin. Moreover, inhibition of JNK and NF-κB abolished hypoxia-induced ES cell apoptosis and inhibition of Akt attenuated delphinidin-induced blockage of apoptosis. The results indicate that delphinidin can prevent hypoxia-induced apoptosis of ES cells through the inhibition of JNK and NF-κB phosphorylation, and restoration of Akt phosphorylation.
    Apoptosis 04/2013; · 4.07 Impact Factor
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    ABSTRACT: Ceramide, a major structural element in the cellular membrane, is a key regulatory factor in various cellular behaviors that are dependent on ceramide-induced association of specific proteins. However, molecular mechanisms that regulate ceramide-induced embryonic stem cell (ESC) migration are still not well understood. Thus, we investigated the effect of ceramide on migration and its related signal pathways in mouse ESCs. Among ceramide species with different fatty acid chain lengths, C(16)-Cer increased migration of mouse ESCs in a dose- (≥1μM) and time-dependent (≥8h) manners, as determined by the cell migration assay. C(16)-Cer (10μM) increased protein-kinase C (PKC) phosphorylation. Subsequently, C(16)-Cer increased focal adhesion kinase (FAK) and Paxillin phosphorylation, which were inhibited by PKC inhibitor Bisindolylmaleimide I (1μM). When we examined for the downstream signaling molecules, C(16)-Cer activated small G protein (Cdc42) and increased the formation of complex with Neural Wiskott-Aldrich Syndrome Protein (N-WASP)/Cdc42/Actin-Related Protein 2/3 (Arp2/3). This complex formation was disrupted by FAK- and Paxillin-specific siRNAs. Furthermore, C(16)-Cer-induced increase of filamentous actin (F-actin) expression was inhibited by Cdc42-, N-WASP-specific siRNAs, or Arp2/3-specific siRNA, respectively. Indeed, C(16)-Cer increased cofilin-1/F-actin interaction or F-actin/α-actinin-1 and α-actinin-4 interactions in the cytoskeleton compartment, which was reversed by Cdc42-specific siRNA. Finally, C(16)-Cer-induced increase of cell migration was inhibited by knocking down each signal pathway-related molecules with siRNA or inhibitors. In conclusion, C(16)-Cer enhances mouse ESC migration through the regulation of PKC and FAK/Paxillin-dependent N-WASP/Cdc42/Arp2/3 complex formation as well as through promoting the interaction between cofilin-1 or α-actinin-1/-4 and F-actin.
    Biochimica et Biophysica Acta 09/2012; · 4.66 Impact Factor
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    ABSTRACT: Long-term estrogen actions are vital for driving cell growth, but more recent evidence suggests that estrogen mediates more rapid cellular effects. However, the function of estradiol-17β (E(2))-BSA in mouse embryonic stem cells has not been reported. Therefore, we examined the role of E(2)-BSA in mouse embryonic stem cell motility and its related signal pathways. E(2)-BSA (10(-8) m) significantly increased motility after 24 h incubation and increased filamentous (F)-actin expression; these effects were inhibited by the estrogen receptor antagonist ICI 182,780, indicating that E(2)-BSA bound membrane estrogen receptors and initiated a signal. E(2)-BSA increased c-Src and focal adhesion kinase (FAK) phosphorylation, which was attenuated by ICI 182,780. The E(2)-BSA-induced increase in epidermal growth factor receptor (EGFR) phosphorylation was inhibited by Src inhibitor PP2. As a downstream signal molecule, E(2)-BSA activated cdc42 and increased formation of a complex with the neural Wiskott-Aldrich syndrome protein (N-WASP)/cdc42/transducer of cdc42-dependent actin assembly-1 (TOCA-1), which was inhibited by FAK small interfering RNA (siRNA) and EGFR inhibitor AG 1478. In addition, E(2)-BSA increased profilin-1 expression and cofilin-1 phosphorylation, which was blocked by cdc42 siRNA. Subsequently, E(2)-BSA induced an increase in F-actin expression, and cell motility was inhibited by each signal pathway-related siRNA molecule or inhibitors but not by cofilin-1 siRNA. A combined treatment of cofilin-1 siRNA and E(2)-BSA increased F-actin expression and cell motility more than that of E(2)-BSA alone. These data demonstrate that E(2)-BSA stimulated motility by interacting with profilin-1/cofilin-1 and F-actin through FAK- and c-Src/EGFR transactivation-dependent N-WASP/cdc42/TOCA-1 complex.
    Molecular Endocrinology 06/2012; 26(8):1291-303. · 4.75 Impact Factor
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    ABSTRACT: Extracellular matrix (ECM) components and intracellular pH (pH(i)) may serve as regulators of cell migration in various cell types. The Oris migration assay was used to assess the effect of fibronectin (FN) on cell motility. The Na(+)/H(+) exchanger (NHE)-1 activity was evaluated by measuring pH(i) and [(22)Na(+)] uptake. To examine activated signaling molecules, western blot analysis and immunoprecipitation was performed. ECM components (FN, laminin, fibrinogen, and collagen type I) increased [(22)Na(+)] uptake, pH(i), and cell migration. In addition, FN-induced increase of cell migration was inhibited by NHE-1 inhibitor amiloride or NHE-1-specific siRNA. FN selectively increased the mRNA and protein expression of NHE-1, but not that of NHE-2 or NHE-3. FN binds integrin β1 and subsequently stimulates caveolin-1 phosphorylation and Ca(2+) influx. Then, NHE-1 is phosphorylated by RhoA and Rho kinases, and Ca(2+)/calmodulin (CaM) signaling elicits complex formation with NHE-1, which is enriched in lipid raft/caveolae microdomains of the plasma membrane. Activation of NHE-1 continuously induces an increase of [(22)Na(+)] uptake and pH(i). Finally, NHE-1-dependent extracellular signal-regulated kinase (ERK) 1/2 phosphorylation enhanced matrix metalloproteinase-2 (MMP-2) and filamentous-actin (F-actin) expression, partially contributing to the regulation of embryonic stem cells (ESCs) migration. FN stimulated mESCs migration and proliferation through NHE-1 activation, which were mediated by lipid raft-associated caveolin-1, RhoA/ROCK, and Ca(2+)/CaM signaling pathways. The precise role of NHE in the modulation of ECM-related physiological functions such as proliferation and migration remains poorly understood. Thus, this study analyzed the relationship between FN and NHE in regulating the migration of mouse ESCs and their related signaling pathways.
    Biochimica et Biophysica Acta 06/2012; 1820(10):1618-27. · 4.66 Impact Factor
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    ABSTRACT: Regulation of glucose transporter (GLUT) expression and activity plays a vital role in the supply of glucose to embryonic stem (ES) cells. To observe the effect of 6-phenyl cyclic monophosphate (cAMP) on glucose uptake and cell proliferation, 2-deoxyglucose (2-DG) uptake, immunohistochemistry, Western blotting, and immunoprecipitation were carried out. Among GLUT isoforms in mouse ES cells, GLUT1 was predominantly expressed and 6-phenyl cAMP increased GLUT mRNA levels. Among cAMP agonists, 6-phenyl cAMP increased 2-DG uptake more than that of 8-p-chlorophenylthio-2'-O-methyl-cAMP. 6-Phenyl cAMP increased GLUT1 expression and translocation from the cytosol to the plasma membrane. 6-Phenyl cAMP increased 2-DG uptake in a time- and concentration-dependent manner due to an increase in V(max) but not K(m). 6-Phenyl cAMP increased phosphorylation of nuclear factor-κB (NF-κB) and cAMP response element binding (CREB) and expression of the CREB protein (CBP) and transducer of regulated CREB activity 2 (TORC2) in sequence. 6-Phenyl cAMP induced complex formation of NF-κB/CREB/CBP/TORC2, which are involved in the increase of gluconeogenic enzyme expression. 6-Phenyl cAMP also increased cell cycle regulatory protein expression levels, the proportion of S-phase cells, and proto-oncogene expression via protein kinase A (PKA)-dependent NF-κB signaling. Finally, GLUT1 siRNA blocked the 6-phenyl cAMP-induced increase in ES cell proliferation. We conclude that PKA stimulated the complex formation of CREB/CBP/TORC2 via NF-κB, which induced effective coordination of glucose uptake as well as proliferation in ES cells. 6-Phenyl cAMP-induced PKA activation modified the proliferation, which may be beneficial for expanding ES cell use to cell therapy.
    Biochimica et Biophysica Acta 05/2012; 1820(10):1636-46. · 4.66 Impact Factor
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    ABSTRACT: Previous studies shows that connexins appear very early during murine embryo development, the gap junctional intercellular communication found in the inner cell mass of early embryo is also maintained in embryonic stem cells (ESC), and expression of oxytocin receptor (OTR) is developmentally regulated at early embryonic development. However, effect of oxytocin (OT) on the regulation of the connexin43 (Cx43) and maintenance of undifferentiation is not fully understood in stem cells. Therefore, we investigated the effect of OT on Cx43 expression and related signaling cascades in mouse ESC. OT increased Cx43 expression that was inhibited by the OTR inhibitor atosiban. In experiments to examine whether the effect of OT depends on lipid rafts, caveolin-1 (cav-1), cav-2, and flotillin-2, but not OTR, were detected in lipid raft fractions. Also, colocalization of OTR, cav-1, and cav-2 was not detected. Moreover, the lipid raft disruptor methyl-β-cyclodextrin did not attenuate OT-induced Cx43 expression. In experiments to examine related signaling pathways, OT activated cAMP/protein kinase A (PKA) which was inhibited by adenylyl cyclase inhibitor SQ 22536 and PKA inhibitor PKI. OT increased nuclear factor κ-light-chain-enhancer of activated B cells (NF-κB) phosphorylation which was inhibited by PKI. OT also increased cAMP response element-binding (CREB)/CREB-binding protein (CBP) expression in the nucleus and induced the formation of CREB1/NF-κB/CBP complexes, which was blocked by the NF-κB-specific small interfering RNA, NF-κB inhibitors, SN50, and bay11-7082. Complex disruption by NF-κB inhibitors decreased OT-induced Cx43 expression. In conclusion, OT stimulates Cx43 expression through the NF-κB/CREB/CBP complex via the lipid raft-independent OTR-mediated cAMP/PKA in mouse ESC.
    Molecular Endocrinology 05/2012; 26(7):1144-57. · 4.75 Impact Factor
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    ABSTRACT: Although previous reports have examined the function of prostaglandin E(2) (PGE(2) ) on gap junctions and undifferentiated stem cells, its effects on the reciprocal action of connexin (Cx) isoforms and undifferentiation in embryonic stem cells (ESCs) are unclear. Therefore, we investigated the role of PGE(2) on Cx isoforms and maintenance of mouse ESC undifferentiated state. We have analysed 10 Cx genes, but found nine of them. PGE(2) (50 μM) stimulated Cx31, Cx32, Cx40, Cx43 and Cx45 mRNA expression. Amongst them, PGE(2) maximally stimulated the Cx43 mRNA expression and gap junction inter-cellular coupling. Therefore, we investigated the effect of PGE(2) on Cx43 expression. PGE(2) activated cAMP/protein kinase A (PKA) and phosphatidylinositol 3-kinase (PI3K)/Akt phosphorylation. In addition, treatments of adenylate cyclase activators increased Cx43 expression, but not PI3K/Akt phosphorylation. PGE(2) also inactivated GSK-3β and stimulated active-β-catenin. Furthermore, a ChiP assay demonstrated the association of β-catenin with the Cx26 (as control) and Cx43 promoter. Finally, down-regulation of PGE(2) -induced Cx isoforms by AH 6809, Cx31-, Cx43-, Cx45 small interfering (si)RNA and 18α-glycyrrhetinic acid decreased levels of undifferentiated markers of ESCs, including Oct4, FoxD3, Sox2 and SSEA-1, but Nanog did not be down-regulated by Cx43 siRNA. PGE(2) stimulates Cx isoforms via GSK-3β/β-catenin via EP2-receptor-dependent cAMP/PKA and PI3K/Akt in mouse ESCs, thereby partially contributing to the maintenance of their undifferentiated state.
    Biology of the Cell 03/2012; 104(7):378-96. · 3.49 Impact Factor
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    ABSTRACT: Prostaglandin E(2) (PGE(2)) is well known to regulate cell functions through cAMP; however, the role of exchange protein directly activated by cAMP (Epac1) and protein kinase A (PKA) in modulating such functions is unknown in human umbilical cord blood-derived mesenchymal stem cells (hUCB-MSCs). Therefore, we investigated the relationship between Epac1 and PKA during PGE(2)-induced hUCB-MSC proliferation and its related signaling pathways. PGE(2) increased cell proliferation, and E-type prostaglandin (EP) 2 receptor mRNA expression level and activated cAMP generation, which were blocked by EP2 receptor selective antagonist AH 6809. PGE(2) increased Epac1 expression, Ras-related protein 1 (Rap1) activation level, and Akt phosphorylation, which were inhibited by AH 6809, adenylyl cyclase inhibitor SQ 22536, and Epac1/Rap1-specific siRNA. Also, PGE(2) increased PKA activity, which was inhibited by AH 6809, SQ 22536, and PKA inhibitor PKI. HUCB-MSCs were incubated with the Epac agonist 8-pCPT-cAMP or the PKA agonist 6-phe-cAMP to examine whether Epac1/Rap1/Akt activation was independent of PKA activation. 8-pCPT-cAMP increased Akt phosphorylation but not PKA activity. 6-Phe-cAMP increased PKA activity, but not Akt phosphorylation. Additionally, an Akt inhibitor or PKA inhibitor (PKI) did not block the PGE(2) -induced increase in PKA activity or Akt phosphorylation, respectively. Moreover, PGE(2) increased glycogen synthase kinase (GSK)-3β phosphorylation and nuclear translocation of active-β-catenin, which were inhibited by Akt inhibitor or/and PKI. PGE(2) increased c-Myc and vascular endothelial growth factor (VEGF) expression levels, which were blocked by β-catenin siRNA. In conclusion, PGE(2) stimulated hUCB-MSC proliferation through β-catenin-mediated c-Myc and VEGF expression via Epac/Rap1/Akt and PKA cooperation.
    Journal of Cellular Physiology 02/2012; 227(12):3756-67. · 4.22 Impact Factor
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    Yu Jin Lee, Mi Ok Kim, Jung Min Ryu, Ho Jae Han
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    ABSTRACT: This study demonstrated that exchange proteins directly activated by cAMP (Epac) and protein kinase A (PKA) by 8-bromo (8-Br)-adenosine 3',5'-cyclic monophosphate (cAMP) stimulated [(14)C]-α-methyl-D-glucopyranoside (α-MG) uptake through increased sodium-glucose cotransporters (SGLTs) expression and translocation to lipid rafts in renal proximal tubule cells (PTCs). In PTCs, SGLTs were colocalized with lipid raft caveolin-1 (cav-1), disrupted by methyl-β-cyclodextrin (MβCD). Selective activators of Epac or PKA, 8-Br-cAMP, and forskolin stimulated expressions of SGLTs and α-MG uptake in PTCs. In addition, 8-Br-cAMP-induced PKA and Epac activation increased phosphorylation of extracellular signal-regulated kinase (ERK), p38 mitogen-activated protein kinase (MAPK), and nuclear factor kappa B (NF-κB), which were involved in expressions of SGLTs. Furthermore, 8-Br-cAMP stimulated SGLTs translocation to lipid rafts via filamentous actin (F-actin) organization, which was blocked by cytochalasin D. In addition, cav-1 and SGLTs stimulated by 8-Br-cAMP were detected in lipid rafts, which were blocked by cytochalasin D. Furthermore, 8-Br-cAMP-induced SGLTs translocation and α-MG uptake were attenuated by inhibition of cav-1 activation with cav-1 small interfering RNA (siRNA) and inhibition of F-actin organization with TRIO and F-actin binding protein (TRIOBP). In conclusion, 8-Br-cAMP stimulated α-MG uptake via Epac and PKA-dependent SGLTs expression and trafficking through cav-1 and F-actin in PTCs.
    Biochimica et Biophysica Acta 01/2012; 1823(4):971-82. · 4.66 Impact Factor
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    ABSTRACT: Magnetic resonance imaging (MRI) of six Yukatan minipig brains was performed. The animals were placed in stereotaxic conditions currently used in experiments. To allow for correctpositioning of the animal in the MRI instrument, landmarks were previously traced on the snout of the pig. To avoid movements, animal were anesthetized. The animals were placed in a prone position in a Siemens Magnetom Avanto 1.5 System with a head coil. Axial T2-weighted and sagittal T1-weighted MRI images were obtained from each pig. Afterwards, the brains of the pigs were fixed and cut into axial sections. Histologic and MR images were compared. The usefulness of this technique is discussed.
    Laboratory animal research. 12/2011; 27(4):309-16.
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    ABSTRACT: Due primarily to the increasing shortage of allogeneic donor organs, xenotransplantation has become the focus of a growing field of research. Currently, micropigs are the most suitable donor animal for humans. However, no standard method has been developed to evaluate the systemic vascular anatomy of micropigs and standard reference values to aid in the selection of normal healthy animals as potential organ donors are lacking. Using 64-channel multidetector row computed tomographic angiography (MDCTA), we evaluated morphological features of the major systemic vessels in micropigs and compared our results to published human data. The main vasculature of the animals was similar to that of humans, except for the iliac arterial system. However, diameters of the major systemic vessels were significantly different between micropigs and humans. Specifically, the diameter of the aortic arch, abdominal aorta, external iliac artery, and femoral artery, were measured as 1.50 ± 0.07 cm, 0.85 ± 0.06 cm, 0.52 ± 0.05 cm, and 0.48 ± 0.05 cm, respectively, in the micropigs. This MDCTA data for micropig major systemic vessels can be used as standard reference values for xenotransplantation studies. The use of 64-channel MDCTA enables accurate evaluation of the major systemic vasculature in micropigs.
    Journal of veterinary science (Suwŏn-si, Korea) 09/2011; 12(3):209-14. · 0.89 Impact Factor
  • Jung Min Ryu, Ho Jae Han
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    ABSTRACT: Although amino acids can function as signaling molecules in the regulation of many cellular processes, mechanisms surrounding L-threonine involvement in embryonic stem cell (ESC) functions have not been explored. Thus, we investigated the effect of L-threonine on regulation of mouse (m)ESC self-renewal and related signaling pathways. In L-threonine-depleted mESC culture media mRNA of self-renewal marker genes, [(3)H]thymidine incorporation, expression of c-Myc, Oct4, and cyclins protein was attenuated. In addition, resupplying L-threonine (500 μM) after depletion restores/maintains the mESC proliferation. Disruption of the lipid raft/caveolae microdomain through treatment with methyl-β-cyclodextrin or transfection with caveolin-1 specific small interfering RNA blocked L-threonine-induced proliferation of mESCs. Addition of L-threonine induced phosphorylation of Akt, ERK, p38, JNK/SAPK, and mTOR in a time-dependent manner. This activity was blocked by LY 294002 (PI3K inhibitor), wortmannin (PI3K inhibitor), or an Akt inhibitor. L-threonine-induced activation of mTOR, p70S6K, and 4E-BP1 as well as cyclins and Oct4 were blocked by PD 98059 (ERK inhibitor), SB 203580 (p38 inhibitor) or SP 600125 (JNK inhibitor). Furthermore, L-threonine induced phosphorylation of raptor and rictor binding to mTOR was completely inhibited by 24 h treatment with rapamycin (mTOR inhibitor); however, a 10 min treatment with rapamycin only partially inhibited rictor phosphorylation. L-threonine induced translocation of rictor from the membrane to the cytosol/nuclear, which blocked by pretreatment with rapamycin. In addition, rapamycin blocked L-threonine-induced increases in mRNA expressions of trophoectoderm and mesoderm marker genes and mESC proliferation. In conclusion, L-threonine stimulated ESC G(1)/S transition through lipid raft/caveolae-dependent PI3K/Akt, MAPKs, mTOR, p70S6K, and 4E-BP1 signaling pathways.
    Journal of Biological Chemistry 05/2011; 286(27):23667-78. · 4.65 Impact Factor
  • Seung Pil Yun, Jung Min Ryu, Ho Jae Han
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    ABSTRACT: Although glucocorticoids strongly affect numerous biological processes including cell growth, development, and homeostasis, their effects on migration of human mesenchymal stem cells (hMSCs) are unclear. Therefore, we investigated the role of dexamethasone (DEX) and its related signaling pathways on migration of hMSCs. We found that DEX, at 10(-8) to 10(-6) M, significantly increased migration after a 24 h incubation, and DEX (10(-6) M) increased migration at >12 h. Moreover, DEX (10(-6) M) increased the level of glucocorticoid receptor (GR)-α mRNA and protein expression, but not GR-β mRNA. The increases in DEX-induced migration were inhibited by the GR antagonist mifepristone (10(-7) M). In addition, DEX increased integrin-linked kinase (ILK) and α-parvin expression but did not change PINCH-1/2 expression in lysate. DEX also increased formations of complex with ILK and α-parvin, and ILK and PINCH-1/2 as shown by immunoprecipitation, which were all inhibited by mifepristone. DEX-induced migration was blocked by ILK and α-parvin small interfering(si)RNAs. In addition, DEX increased focal adhesion kinase (FAK) and paxillin expression, which were attenuated by ILK and α-parvin siRNAs. DEX-induced cell migration was inhibited by FAK/paxillin siRNAs. DEX also increased β1-integrin expression, which was blocked by FAK/paxillin siRNAs. In addition, DEX-induced cell migration was inhibited by β1-integrin siRNA. Downregulation of ILK, α-parvin, FAK/paxillin and β1-integrin expression by siRNAs decreased DEX-induced filamentous(F)-actin organization and migration of hMSCs. In conclusion, DEX partially stimulates hMSC migration by the expression of β1-integrin through formation of a PINCH-1/2/ILK/α-parvin complex (PIP complex), and FAK and paxillin expression.
    Journal of Cellular Physiology 03/2011; 226(3):683-92. · 4.22 Impact Factor
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    ABSTRACT: Although many previous reports have examined the function of prostaglandin E(2) (PGE(2)) in the migration and proliferation of various cell types, the role of the actin cytoskeleton in human mesenchymal stem cells (hMSCs) migration and proliferation has not been reported. The present study examined the involvement of profilin-1 (Pfn-1) and filamentous-actin (F-actin) in PGE(2)-induced hMSC migration and proliferation and its related signal pathways. PGE(2) (10(-6) M) increased both cell migration and proliferation, and also increased E-type prostaglandin receptor 2 (EP2) mRNA expression, β-arrestin-1 phosphorylation, and c-Jun N-terminal kinase (JNK) phosphorylation. Small interfering RNA (siRNA)-mediated knockdown of β-arrestin-1 and JNK (-1, -2, -3) inhibited PGE(2)-induced growth of hMSCs. PGE(2) also activated Pfn-1, which was blocked by JNK siRNA, and induced F-actin level and organization. Downregulation of Pfn-1 by siRNA decreased the level and organization of F-actin. In addition, specific siRNA for TRIO and F-actin-binding protein (TRIOBP) reduced the PGE(2)-induced increase in hMSC migration and proliferation. Together, these experimental data demonstrate that PGE(2) partially stimulates hMSCs migration and proliferation by interaction of Pfn-1 and F-actin via EP2 receptor-dependent β-arrestin-1/JNK signaling pathways.
    Journal of Cellular Physiology 02/2011; 226(2):559-71. · 4.22 Impact Factor
  • Jae Hong Park, Jung Min Ryu, Ho Jae Han
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    ABSTRACT: Fibronectin (FN) is the foremost proliferation-associated extracellular matrix component promoting cell adhesion, migration, and survival. We examined the effect of FN on cell proliferation and the related signaling pathways in mouse embryonic stem (ES) cells. FN increased integrin β1, Src, focal adhesion kinase (FAK), and caveolin-1 phosphorylation levels in a time-dependent manner. Phosphorylation of Src, FAK, and caveolin-1 was attenuated by integrin β1 neutralizing antibody. Integrin β1, Src, and FAK coimmunoprecipitated with caveolin-1 in the presence of FN. In addition, FN increased RhoA and Rho kinase activation, which were completely blocked by PP2, FAK small interfering RNA (siRNA), caveolin-1 siRNA, or the caveolar disruptor methyl-β-cyclodextrin (MβCD). FN also increased phosphorylation of Akt and ERK 1/2, which were significantly blocked by either FAK siRNA, caveolin-1 siRNA, MβCD, GGTI-286 (RhoA inhibitor), or Y-27632 (Rho kinase inhibitor). FN-induced increase of protooncogenes (c-fos, c-myc, and c-Jun) and cell-cycle regulatory proteins (cyclin D1/CDK4 and cyclin E/CDK2) expression levels were attenuated by FAK siRNA or caveolin-1 siRNA. Furthermore, inhibition of each pathway such as integrin β1, Src, FAK, caveolin-1, RhoA, Akt, and ERK 1/2 blocked FN-induced [(3)H]-thymidine incorporation. We conclude that FN stimulates mouse ES cell proliferation via RhoA-PI3K/Akt-ERK 1/2 pathway through caveolin-1 phosphorylation.
    Journal of Cellular Physiology 01/2011; 226(1):267-75. · 4.22 Impact Factor

Publication Stats

175 Citations
105.40 Total Impact Points

Institutions

  • 2012–2014
    • Seoul National University
      • • College of Veterinary Medicine
      • • Research Institute of Veterinary Medicine
      Sŏul, Seoul, South Korea
  • 2008–2013
    • Chonnam National University
      • College of Veterinary Medicine
      Gwangju, Gwangju, South Korea