Ik-Soon Jang

Publications of Ik-Soon Jang

• Lactobacillus caseiExtract Induces Apoptosis in Gastric Cancer by Inhibiting NF-κB and mTOR-Mediated Signaling.

  Authors: Jeong Won Hwang, Young-Mi Baek, Kyeong Eun Yang, Hwa-Seung Yoo, Chong-Kwan Cho, Yeon-Weol Lee, Junsoo Park, Chi-Yong Eom, Zee-Won Lee, Jong-Soon Choi, Ik-Soon Jang

  Integrative cancer therapies. 04/2012;

  Lactobacillus casei extract (LBX) has been reported to prevent gastric cancer, but the underlying mechanism remains unclear. The proliferation and cell death of gastric cancer KATO3 cells wereLactobacillus casei extract (LBX) has been reported to prevent gastric cancer, but the underlying mechanism remains unclear. The proliferation and cell death of gastric cancer KATO3 cells were examined after treatment with LBX for various times and at various doses. LBX inhibited the growth of gastric cancer cells and induced apoptosis by inactivating NF-κB promoter activity. Apoptosis induced by LBX, however, is not directly associated with the intrinsic mitochondrial pathway. Immunoblot analysis revealed that LBX decreased the expressions of NF-κB and IκB. The reduced NF-κB levels led to the decreased phosphorylation of mTOR signaling components, such as PI3K, Akt, and (p70)S6 kinase. These results showed for the first time that LBX induced apoptosis in gastric cancer cells by inhibiting NF-κB and mTOR-mediated signaling.

• Mountain ginseng extract exhibits anti-lung cancer activity by inhibiting the nuclear translocation of NF-κB.

  Authors: Jeong Won Hwang, Jung Han Oh, Hwa-Seung Yoo, Yeon-Weol Lee, Chong-Kwan Cho, Ki-Rok Kwon, Jung-Ho Yoon, Junsoo Park, Song Her, Zee-Won Lee, Ik-Soon Jang, Jong-Soon Choi

  The American journal of Chinese medicine. 01/2012; 40(1):187-202.

  Administration of mountain ginseng (MG) extract can restore advanced cancer to a normal state. To elucidate the mechanism by which MG extract prevents the progression of lung cancer, the processes ofAdministration of mountain ginseng (MG) extract can restore advanced cancer to a normal state. To elucidate the mechanism by which MG extract prevents the progression of lung cancer, the processes of proliferation and death of lung cancer cells (A549) were examined after treatment with MG extract. Butanol-extracted MG (BX-MG) showed a high inhibitory effect (IC(50) = 2 mg/ml) by attenuating proliferation and inducing apoptosis in lung cancer cells. By HPLC-UV analysis of BX-MG, ginsenosides, Rb1 was identified as the most abundant ginsenoside, followed by Rg1, Re, Rc and Rb2. BX-MG induced caspase-3 dependent apoptosis by inhibiting NF-κB. In addition, BX-MG activated p53 and p21, resulting in the attenuated proliferation of A549 cells. Reduced activity of the NF-κB promoter and increased activity of the p53 promoter indicate that BX-MG regulates apoptosis at the level of transcription in lung cancer cells. Furthermore, BX-MG blocked the nuclear translocation of RelA and the associated reduction in surviving. These results suggest that BX-MG inhibits lung cancer cell growth by activating tumor suppressors and inhibiting nuclear translocation of NF-κB.

• Comparative Proteomic Analysis of Human Somatic Cells, Induced Pluripotent Stem Cells, and Embryonic Stem Cells.

  Authors: Sun Young Kim, Min-Jeong Kim, Hyeyun Jung, Won Kon Kim, Sang Oh Kwon, Myung Jin Son, Ik-Soon Jang, Jong-Soon Choi, Sung Goo Park, Byoung Chul Park, Yong-Mahn Han, Sang Chul Lee, Yee Sook Cho, Kwang-Hee Bae

  Stem cells and development. 07/2011;

  Induced pluripotent stem cells (iPSCs) are somatic cells that have been reprogrammed to a pluripotent state via introduction of defined transcription factors. iPSCs are a valuable resource forInduced pluripotent stem cells (iPSCs) are somatic cells that have been reprogrammed to a pluripotent state via introduction of defined transcription factors. iPSCs are a valuable resource for regenerative medicine, but whether iPSCs are identical to embryonic stem cells (ESCs) remains unclear. In this study, we performed comparative proteomic analyses of human somatic cells [human newborn foreskin fibroblasts (hFFs)], human iPSCs (hiPSCs) derived from hFFs, and H9 human ESCs (hESCs). We reprogrammed hFFs to a pluripotent state using 4 core transcription factors: Oct4 (O), Sox2 (S), Klf4 (K), and c-Myc (M). The proteome of hiPSCs induced by 4 core transcription factors was relatively similar to that of hESCs. However, several proteins, including dUTPase, GAPDH, and FUSE binding protein 3, were differentially expressed between hESCs and hiPSCs, implying that hiPSCs are not identical to hESCs at the proteomic level. The proteomes of iPSCs induced by introducing 3, 5, or 6 transcription factors were also analyzed. Our proteomic profiles provide valuable insight into the factors that contribute to the similarities and differences between hESCs and hiPSCs and the mechanisms of reprogramming.

• The expression of damage-regulated autophagy modulator 2 (DRAM2) contributes to autophagy induction.

  Authors: Jung-Ho Yoon, Song Her, Moonhee Kim, Ik-Soon Jang, Junsoo Park

  Molecular biology reports. 05/2011; 39(2):1087-93.

  Autophagy is a membrane trafficking process involved in intracellular degradation and recycling in eukaryotic cells. DRAM2 (damage-regulated autophagy modulator 2) is a homologue of DRAM thatAutophagy is a membrane trafficking process involved in intracellular degradation and recycling in eukaryotic cells. DRAM2 (damage-regulated autophagy modulator 2) is a homologue of DRAM that regulates p53-mediated cell death. As its name implies, DRAM expression induces autophagy in a p53-dependent manner; however, the role of DRAM2 in autophagy is not clear. In this study, we report that DRAM2 expression contributes to autophagy induction. Overexpression of DRAM2 induces cytoplasmic GFP-LC3 punctuates, and increases the level of endogenous LC3-II. Moreover, the silencing of endogenous DRAM2 interferes with starvation-induced autophagy. Thus, we propose that DRAM2 as well as DRAM are involved in autophagy.

• Differential expression of extracellular matrix proteins in senescent and young human fibroblasts: a comparative proteomics and microarray study.

  Authors: Kyeong Eun Yang, Joseph Kwon, Ji-Heon Rhim, Jong Soon Choi, Seung Il Kim, Seung-Hoon Lee, Junsoo Park, Ik-Soon Jang

  Molecules and cells. 05/2011; 32(1):99-106.

  The extracellular matrix (ECM) provides an essential structural framework for cell attachment, proliferation, and differentiation, and undergoes progressive changes during senescence. To investigateThe extracellular matrix (ECM) provides an essential structural framework for cell attachment, proliferation, and differentiation, and undergoes progressive changes during senescence. To investigate changes in protein expression in the extracellular matrix between young and senescent fibroblasts, we compared proteomic data (LTQ-FT) with cDNA microarray results. The peptide counts from the proteomics analysis were used to evaluate the level of ECM protein expression by young cells and senescent cells, and ECM protein expression data were compared with the microarray data. After completing the comparative analysis, we grouped the genes into four categories. Class I included genes with increased expression levels in both analyses, while class IV contained genes with reduced expression in both analyses. Class II and Class III contained genes with an inconsistent expression pattern. Finally, we validated the comparative analysis results by examining the expression level of the specific gene from each category using Western blot analysis and semiquantitative RT-PCR. Our results demonstrate that comparative analysis can be used to identify differentially expressed genes.

• Non-synonymous SNP in the ApoR gene associated with pork meat quality.

  Authors: Yong Hwa Lee, Eun Seok Cho, Eun Jung Kwon, Byeong-Woo Kim, Da Hye Park, Hwa Chun Park, Beom Young Park, Juhyun Nam, Ik Soon Jang, Jong-Soon Choi, Woo Young Bang, Chul Wook Kim

  Bioscience, biotechnology, and biochemistry. 01/2011; 75(10):2018-20.

  Two novel non-synonymous SNPs in the 2nd and 3rd exons of the porcine ApoR gene are reported. One was identified as a novel SNP significantly associated with multiple traits of pork meat quality. TheTwo novel non-synonymous SNPs in the 2nd and 3rd exons of the porcine ApoR gene are reported. One was identified as a novel SNP significantly associated with multiple traits of pork meat quality. The data can provide a useful resource for developing a marker in the genetic improvement of pigs.

• Alpinumisoflavone induces apoptosis and suppresses extracellular signal-regulated kinases/mitogen activated protein kinase and nuclear factor-κB pathways in lung tumor cells.

  Authors: Sim Namkoong, Tack-Joong Kim, Ik-Soon Jang, Keon-Wook Kang, Won-Keun Oh, Junsoo Park

  Biological & pharmaceutical bulletin. 01/2011; 34(2):203-8.

  The extracellular signal-regulated kinases/mitogen activated protein kinase (ERK/MAPK) and nuclear factor-κB (NF-κB) pathways are critical for cell survival and proliferation. AlpinumisoflavoneThe extracellular signal-regulated kinases/mitogen activated protein kinase (ERK/MAPK) and nuclear factor-κB (NF-κB) pathways are critical for cell survival and proliferation. Alpinumisoflavone (AIF), isolated from the African medicinal plant Erythrina lysistemon, is a member of the isoflavone group. In this report, we demonstrated that AIF treatment induces cell death of human lung tumor cells. Incubation of lung tumor cells with AIF increased the sub-G1 population and caspase 3/7 activity, suggesting that the cell death is caused by apoptosis. To identify the signaling pathway involved in the tumor cell death, we examined the modulation of transcriptional activity using various reporter constructs and found that AIF significantly deregulated both the ERK/MAPK and NF-κB pathways. Western blot analysis with antibodies to MAP/ERK kinase (MEK) and ERK showed that AIF dephosphorylates both MEK and ERK. Alpinumisoflavone also repressed lipopolysaccharide (LPS)-induced nitric oxide (NO) production in RAW264.7 cells by inhibiting NF-κB-dependent transcription. Therefore, the cell death induced by AIF may be via repressing both the ERK/MAPK and NF-κB pathways.

• Activation of wound healing in aged rats by altering the cellular mitogenic potential.

  Authors: Ji Heon Rhim, Ik-Soon Jang, Sung Tack Kwon, Kye Yong Song, Eui-Ju Yeo, Sang Chul Park

  The journals of gerontology. Series A, Biological sciences and medical sciences. 07/2010; 65(7):704-11.

  We previously showed that lysophosphatidic acid (LPA) and an adenylyl cyclase inhibitor (ACI) stimulate mitogenic activation of senescent human diploid fibroblasts. Because the modulation of cellWe previously showed that lysophosphatidic acid (LPA) and an adenylyl cyclase inhibitor (ACI) stimulate mitogenic activation of senescent human diploid fibroblasts. Because the modulation of cell proliferation may affect wound healing in aged organisms, we studied the effects of LPA and ACI on in vivo skin wound healing in aged Fisher 344 rats. We found that, in aged rats, wound healing improved in animals treated with LPA and/or ACI (relative to untreated controls), as assessed by histological analysis of reepithelialization and immunostaining for proliferating cell nuclear antigen. The age-dependent activation of mitogenic responses by LPA and ACI was confirmed in other cell types. Taken together, our findings suggest that the activation of mitogenic potential in senescent cells by LPA and/or ACI may translate into enhanced in vivo wound healing and tissue regeneration in aged animals.

• Caveolae-mediated entry of Salmonella typhimurium into senescent nonphagocytotic host cells.

  Authors: Jae Sung Lim, Hyon E Choy, Sang Chul Park, Jung Min Han, Ik-Soon Jang, Kyung A Cho

  Aging cell. 04/2010; 9(2):243-51.

  Elderly individuals have an increased susceptibility to microbial infections because of age-related anatomical, physiological, and environmental factors. However, the mechanism of aging-dependentElderly individuals have an increased susceptibility to microbial infections because of age-related anatomical, physiological, and environmental factors. However, the mechanism of aging-dependent susceptibility to infection is not fully understood. Here, we found that caveolae-dependent endocytosis is elevated in senescent cells. Thus, we focused on the implications of caveolae-dependent endocytosis using Salmonella typhimurium, which causes a variety of diseases in humans and animals by invading the eukaryotic host cell. Salmonella invasion increased in nonphagocytotic senescent host cells in which caveolin-1 was also increased. When caveolae structures were disrupted by methyl-beta-cyclodextrin or siRNA of caveolin-1 in the senescent cells, Salmonellae invasion was reduced markedly compared to that in nonsenescent cells. In contrast, the over-expression of caveolin-1 led to increased Salmonellae invasion in nonsenescent cells. Moreover, in aged mice, caveolin-1 was found to be highly expressed in Peyer's patch and spleen, which are targets for infection by Salmonellae. These results suggest that high levels of caveolae and caveolin-1 in senescent host cells might be related to the increased susceptibility of elderly individuals to microbial infections.

• Activation of AMP-activated protein kinase stimulates the nuclear localization of glyceraldehyde 3-phosphate dehydrogenase in human diploid fibroblasts.

  Authors: Hyun Jin Kwon, Ji Heon Rhim, Ik-Soon Jang, Go-Eun Kim, Sang Chul Park, Eui-Ju Yeo

  Experimental & molecular medicine. 02/2010; 42(4):254-69.

  In addition to its well-known glycolytic activity, GAPDH displays multiple functions, such as nuclear RNA export, DNA replication and repair, and apoptotic cell death. This functional diversityIn addition to its well-known glycolytic activity, GAPDH displays multiple functions, such as nuclear RNA export, DNA replication and repair, and apoptotic cell death. This functional diversity depends on its intracellular localization. In this study, we explored the signal transduction pathways involved in the nuclear translocation of GAPDH using confocal laser scanning microscopy of immunostained human diploid fibroblasts (HDFs). GAPDH was present mainly in the cytoplasm when cultured with 10% FBS. Serum depletion by culturing cells in a serum-free medium (SFM) led to a gradual accumulation of GAPDH in the nucleus, and this nuclear accumulation was reversed by the re-addition of serum or growth factors, such as PDGF and lysophosphatidic acid. The nuclear export induced by the re-addition of serum or growth factors was prevented by LY 294002 and SH-5, inhibitors of phosphoinositide 3-kinase (PI3K) and Akt/protein kinase B, respectively, suggesting an involvement of the PI3K signaling pathway in the nuclear export of GAPDH. In addition, 5-aminoimidazole-4-carboxamide-1-beta-D-ribofuranoside (AICAR), an activator of AMP-activated protein kinase (AMPK), stimulated the nuclear translocation of GAPDH and prevented serum- and growth factor-induced GAPDH export. AMPK inhibition by compound C or AMPK depletion by siRNA treatment partially prevented SFM- and AICAR-induced nuclear translocation of GAPDH. Our data suggest that the nuclear translocation of GAPDH might be regulated by the PI3K signaling pathway acting mainly as a nuclear export signal and the AMPK signaling pathway acting as a nuclear import signal.

• SUMOylated IRF-1 shows oncogenic potential by mimicking IRF-2.

  Authors: Sun-Mi Park, Myounghee Chae, Bo-Kyoung Kim, Taegun Seo, Ik-Soon Jang, Jong-Soon Choi, Il-Chul Kim, Je-Ho Lee, Junsoo Park

  Biochemical and biophysical research communications. 12/2009;

  Interferon regulatory factor-1 (IRF-1) is an interferon-induced transcriptional activator that suppresses tumors by impeding cell proliferation. Recently, we demonstrated that the level of SUMOylatedInterferon regulatory factor-1 (IRF-1) is an interferon-induced transcriptional activator that suppresses tumors by impeding cell proliferation. Recently, we demonstrated that the level of SUMOylated IRF-1 is elevated in tumor cells, and that SUMOylation of IRF-1 attenuates its tumor-suppressive function. Here we report that SUMOylated IRF-1 mimics IRF-2, an antagonistic repressor, and shows oncogenic potential. To demonstrate the role of SUMOylated IRF-1 in tumorigenesis, we used SUMO-IRF-1 recombinant protein. Stable expression of SUMO-IRF-1 in NIH3T3 cells resulted in focus formation and anchorage-independent growth in soft agar. Inoculation of SUMO-IRF-1-transfected cells into athymic nude mice resulted in tumor formation and infiltration of adipose tissues. Finally, we demonstrated that SUMO-IRF-1 transforms NIH3T3 cells in a dose-dependent manner suggesting that SUMOylated IRF-1 may act as an oncogenic protein in tumor cells.

• Reduced expression of DRAM2/TMEM77 in tumor cells interferes with cell death.

  Authors: Sun-Mi Park, Kwangsoo Kim, Eun Ju Lee, Bo-Kyoung Kim, Tae Jin Lee, Taegun Seo, Ik-Soon Jang, Sang-Hoon Lee, Soohyun Kim, Je-Ho Lee, Junsoo Park

  Biochemical and biophysical research communications. 11/2009;

  Although the role of autophagy in tumorigenesis remains controversial, recent reports support the notion that inhibition of autophagy promotes tumor formation. Damage-regulated autophagy regulatorAlthough the role of autophagy in tumorigenesis remains controversial, recent reports support the notion that inhibition of autophagy promotes tumor formation. Damage-regulated autophagy regulator (DRAM) has been identified as an effector molecule that is critical for p53-mediated apoptosis, and we investigated whether there might be other DRAM-like molecules linking autophagy and apoptosis. In this study, we cloned a novel DRAM-homologous protein, DRAM2, and showed that the expression of DRAM2 is down-regulated in ovarian tumors. DRAM2 is mainly localized in the lysosome, and co-localizes with DRAM. While expression of DRAM or DRAM2 individually did not induce cell death, co-expression of DRAM2 with DRAM significantly induced cell death, while the silencing of endogenous DRAM2 attenuated cell death, suggesting that DRAM2 is involved in cell death. Thus, we propose that reduced expression of DRAM2 may contribute to enhanced cell survival in tumor cells.

• Time-dependent differential gene expression in lysophosphatidic acid-treated young and senescent human diploid fibroblasts.

  Authors: Ji Heon Rhim, Ik-Soon Jang, Hyun Jin Kwon, Eui-Ju Yeo, Sang Chul Park

  Mechanisms of ageing and development. 07/2009;

  The gene expression profiles of lysophosphatidic acid (LPA)-treated young and senescent human diploid fibroblasts (HDFs) were examined using cDNA microarray analysis. The expression of some genes,The gene expression profiles of lysophosphatidic acid (LPA)-treated young and senescent human diploid fibroblasts (HDFs) were examined using cDNA microarray analysis. The expression of some genes, including EGR 1/3 and MRRF, was controlled by LPA similarly in young and senescent cells, showing a typical time-dependent up-and-down expression profile. In contrast, some other genes, including DUSP6, CYR61, and F3, showed sustained upregulation in senescent HDFs later after LPA treatment. These genes might be involved in altered LPA responsiveness during the aging process.

• ATG5 expression induced by MDMA (ecstasy), interferes with neuronal differentiation of neuroblastoma cells.

  Authors: Myounghee Chae, Gyu-Seek Rhee, Ik-Soon Jang, Kwangsoo Kim, Ji-Hae Lee, Seung-Yeul Lee, Minjung Kim, Junyoung Yang, Junsoo Park, Seung-Hoon Lee

  Molecules and cells. 06/2009; 27(5):571-5.

  The amphetamine derivative 3, 4-methylenedioxymethamphetamine (MDMA) has become a popular recreational drug, and has also been shown to cause serotonergic neurotoxicity. This report shows that MDMAThe amphetamine derivative 3, 4-methylenedioxymethamphetamine (MDMA) has become a popular recreational drug, and has also been shown to cause serotonergic neurotoxicity. This report shows that MDMA impairs brain development in a whole mouse embryo culture. The results of quantitative real-time PCR analysis showed that autophagy-related protein 5 (Atg5) expression is elevated in mouse embryo and neuroblastoma cells after MDMA treatment. This elevated Atg5 expression interferes with the neuronal differentiation of neuroblastoma cells such as SH-SY5Y and PC12 cells. Thus, our results suggest that the use of MDMA during pregnancy may impair neuronal development via an induction of Atg5 expression.

• Species-specific variation of RPA-interacting protein (RIP) splice isoforms.

  Authors: Kwangsoo Kim, Eun Ju Lee, Seung-Hoon Lee, Taegun Seo, Ik-Soon Jang, Junsoo Park, Je-Ho Lee

  BMB reports. 02/2009; 42(1):22-7.

  Replication Protein A (RPA) is a single stranded DNA-binding protein involved in DNA metabolic activities such as replication, repair, and recombination. RPA-Interacting Protein alpha (RIPalpha) wasReplication Protein A (RPA) is a single stranded DNA-binding protein involved in DNA metabolic activities such as replication, repair, and recombination. RPA-Interacting Protein alpha (RIPalpha) was originally identified as a nuclear transporter of RPA in Xenopus. The human RIPalpha gene encodes several splice isoforms, of which hRIPalpha and hRIPbeta are the major translation products in vivo. However, limited information is available about the alternative splicing of RIPalpha in eukaryotes, apart from that in humans. In this study, we examined the alternative splicing of RIPalpha in the Drosophila, Xenopus, and mouse system. We showed that the number of splice isoforms of RIPalpha was species-specific, and displayed a tendency to increase in higher eukaryotes. Moreover, a mouse ortholog of hRIPbeta, mRIPbeta2, was not SUMOylated, in contrast to hRIPbeta. Based on these results, we suggest that the RIPalpha gene gains more splice isoforms and additional modifications after molecular evolution. [BMB reports 2009; 42(1): 22-27].

• Lysophosphatidic Acid and adenylyl cyclase inhibitor increase proliferation of senescent human diploid fibroblasts by inhibiting adenosine monophosphate-activated protein kinase.

  Authors: Ji Heon Rhim, Ik-Soon Jang, Kye Yong Song, Moon-Kyung Ha, Sung Chun Cho, Eui-Ju Yeo, Sang Chul Park

  Rejuvenation research. 09/2008; 11(4):781-92.

  Abstract This study was designed to elucidate the molecular mechanism underlying lysophosphatidic acid (LPA) and adenylyl cyclase inhibitor SQ22536 (ACI)-induced senescent human diploid fibroblastAbstract This study was designed to elucidate the molecular mechanism underlying lysophosphatidic acid (LPA) and adenylyl cyclase inhibitor SQ22536 (ACI)-induced senescent human diploid fibroblast (HDF) proliferation. Because adenosine monophosphate (AMP)-activated protein kinase (AMPK) is known to inhibit cell proliferation, we examined the phosphorylation status of AMPK and p53 and the expression level of p21(waf1/cip1) after treating HDFs with LPA and ACI. Phosphorylation of AMPKalpha on threonine-172 (p-Thr172-AMPKalpha) increases its catalytic activity but phosphorylation on serine-485/491 (p-Ser485/491-AMPKalpha) reduces the accessibility of the Thr172 phosphorylation site thereby inhibiting its catalytic activity. LPA increased p-Ser485/491-AMPKalpha, presumably by activating cAMP-dependent protein kinase (PKA). However, ACI reduced p-Thr172-AMPKalpha by inhibiting the LKB signaling. Our data demonstrated that both LPA and ACI inhibit the catalytic activity of AMPKalpha and p53 by differentially regulating phosphorylation of AMPKalpha, causing increased senescent cell proliferation. These findings suggest that the proliferation potential of senescent HDFs can be modulated through the regulation of the AMPK signaling pathway.

• IRF-2 regulates NF-kappaB activity by modulating the subcellular localization of NF-kappaB.

  Authors: Myounghee Chae, Kwangsoo Kim, Sun-Mi Park, Ik-Soon Jang, Taegun Seo, Dong Min Kim, Il-Chul Kim, Je-Ho Lee, Junsoo Park

  Biochemical and biophysical research communications. 07/2008; 370(3):519-24.

  Nuclear Factor-kappa B (NF-kappaB) is a transcription factor essential to the control of cell proliferation, survival, differentiation, immune response, and inflammation. Constitutive NF-kappaBNuclear Factor-kappa B (NF-kappaB) is a transcription factor essential to the control of cell proliferation, survival, differentiation, immune response, and inflammation. Constitutive NF-kappaB activation has been observed in a broad variety of solid tumors and hematological malignancies, which suggests that NF-kappaB signaling may perform a critical role in the development of human cancers. Interferon regulatory factor-2 (IRF-2), an antagonistic transcriptional repressor of IRF-1, evidences oncogenic potential, but little is currently known regarding the mechanism underlying the oncogenic activities of IRF-2. In this study, we report that IRF-2 recruits RelA/p65 transcription factors into the nucleus via physical interaction. While the nuclear recruitment of RelA by IRF-2 augments TNFalpha-induced NF-kappaB dependent transcription, the N-terminal truncated mutant form of IRF-2 inhibits the nuclear localization of RelA, and thus interferes with NF-kappaB activation. Furthermore, the knockdown of IRF-2 by IRF-2 siRNA attenuates TNFalpha-induced NF-kappaB dependent transcription by inhibiting the nuclear localization of RelA. Thus, these results show that IRF-2 regulates NF-kappaB activity via the modulation of NF-kappaB subcellular localization.

• Role of protein kinase C-dependent A-kinase anchoring proteins in lysophosphatidic acid-induced cAMP signaling in human diploid fibroblasts.

  Authors: Ji Heon Rhim, Ik-Soon Jang, Eui-Ju Yeo, Kye Yong Song, Sang Chul Park

  Aging cell. 01/2007; 5(6):451-61.

  Previously, we reported that lysophosphatidic acid (LPA)-induced adenosine 3',5'-cyclic monophosphate (cAMP) production by human diploid fibroblasts depends on the age of the fibroblasts. In thisPreviously, we reported that lysophosphatidic acid (LPA)-induced adenosine 3',5'-cyclic monophosphate (cAMP) production by human diploid fibroblasts depends on the age of the fibroblasts. In this study, we examined the role of A-kinase anchoring proteins (AKAP) in the regulation of LPA-stimulated cAMP production in senescent fibroblasts. We found that levels of protein kinase C (PKC)-dependent AKAPs, such as Gravin and AKAP79, were elevated in senescent cells. Co-immunoprecipitation experiments revealed that Gravin and AKAP79 do not associate with adenylyl cyclase type 2 (AC2) but bind to AC4/6, which interacts with calcium-dependent PKCs alpha/beta both in young and senescent fibroblasts. When the expression of Gravin and AKAP79 was blocked by small interference RNA transfection, the basal level of cAMP was greatly reduced and the cAMP status after LPA treatment was also reversed. Protein kinase A showed a similar pattern in terms of its basal activity and LPA-dependent modulation. These data suggest that Gravin and to a lesser extent, AKAP79, may play important roles in maintaining the basal AC activity and in coupling the AC systems to inhibitory signals such as Gialpha in young cells, and to stimulatory signals such as PKCs in senescent cells. This study also demonstrates that Gravin is especially important for the long-term activation of PKC by LPA in senescent cells. We conclude that LPA-dependent increased level of cAMP in senescent human diploid fibroblasts is associated with increases in Gravin levels resulting in its increased binding with and activation of calcium-dependent PKC alpha/beta and AC4/6.

• Lysophosphatidic acid-induced changes in cAMP profiles in young and senescent human fibroblasts as a clue to the ageing process.

  Authors: Ik-Soon Jang, Ji Heon Rhim, Kyung-Tae Kim, Kyung A Cho, Eui-Ju Yeo, Sang Chul Park

  Mechanisms of ageing and development. 06/2006; 127(5):481-9.

  This study attempts to elucidate the molecular mechanisms underlying the ageing-dependent cAMP profiles in human diploid fibroblasts stimulated by lysophosphatidic acid (LPA). In senescent cells,This study attempts to elucidate the molecular mechanisms underlying the ageing-dependent cAMP profiles in human diploid fibroblasts stimulated by lysophosphatidic acid (LPA). In senescent cells, LPA-dependent Gialpha activation was reduced, with a consequent reduction in Gi-suppressed cAMP levels, without alterations in the levels of Gialpha proteins. In young cells, when Gialpha activity was inhibited by pertussis toxin pretreatment, or when its expression was blocked by siRNA, the pattern of changes in cAMP levels in response to LPA was similar to that seen in senescent cells. An increase in protein kinase C (PKC)-dependent isoforms of adenylyl cyclase (AC) types II, IV, and VI was also observed in these senescent fibroblasts. In senescent cells treated with PKC-specific inhibitors, bis-indolylmaleimide, Gö6976, rottlerin, and PKCvarepsilonV1, LPA-induced cAMP accumulation was inhibited, indicating that increased ACs in response to LPA occur via the activation of protein kinase Cs. When the expression of AC II, IV, and VI was blocked by siRNA in senescent fibroblasts, LPA-induced cAMP accumulation was also blocked. These results suggest that the senescence-associated increase of cAMP levels after LPA treatment is associated with reduced Gialpha, increased AC II, IV, and VI proteins, and PKC-dependent stimulation of their activities and provide an explanation for the age-dependent differences in cAMP-related physiological responses.

• Downstream molecular events in the altered profiles of lysophosphatidic acid-induced cAMP in senescent human diploid fibroblasts.

  Authors: Ik-Soon Jang, Ji Heon Rhim, Sang Chul Park, Eui-Ju Yeo

  Experimental & molecular medicine. 05/2006; 38(2):134-43.

  Lysophosphatidic acid (LPA) is a phospholipid growth factor that acts through G-protein-coupled receptors. Previously, we demonstrated an altered profile of LPA-dependent cAMP content during theLysophosphatidic acid (LPA) is a phospholipid growth factor that acts through G-protein-coupled receptors. Previously, we demonstrated an altered profile of LPA-dependent cAMP content during the aging process of human diploid fibroblasts (HDFs). In attempts to define the molecular events associated with the age-dependent changes in cAMP profiles, we determined the protein kinase A (PKA) activity, phosphorylation of cAMP-response element binding protein (CREB), and the protein expression of CRE-regulatory genes, c-fos and COX-2 in young and senescent HDFs. We observed in senescent cells, an increase in mRNA levels of the catalytic subunit a of PKA and of the major regulatory subunit Ialpha. Senescence-associated increase of cAMP after LPA treatment correlated well with increased CREB phosphorylation accompanying activation of PKA in senescent cells. In senescent cells, after LPA treatment, the expression of c-fos and COX-2 decreased initially, followed by an increase. In young HDFs, CREB phosphorylation decreased following LPA treatment, and both c-fos and COX-2 protein levels increased rapidly. CRE-luciferase assay revealed higher basal CRE-dependent gene expression in young HDFs compared to senescent HDFs. However, LPA-dependent slope of luciferase increased more rapidly in senescent cells than in young cells, presumably due to an increase of LPA-induced CREB phosphorylation. CRE-dependent luciferase activation was abrogated in the presence of inhibitors of PKC, MEK1, p38MAPK, and PKA, in both young and senescent HDFs. We conclude that these kinase are coactivators of the expression of CRE-responsive genes in LPA-induced HDFs and that their changed activities during the aging process contribute to the final expression level of CRE-responsive genes.