• BMB Reports
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• v.34 no.1
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• pp.73-79
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• 2001

Transcriptional activation domains are known to be inherently "unstructured" with no tertiary structure. A recent NMR study, however, has shown that the transactivation domain in human p53 is populated with an amphipathic helix and two nascent turns. This suggests that the presence of such local secondary structures within the overall "unstructured" structural framework is a general feature of acidic transactivation domains. These pre-existing local structures in p53, formed selectively by positional conserved hydrophobic residues that are known to be critical for transcriptional activity, thus appear to constitute the specific structural motifs that regulate recognition of the p53 transactivation domain by target proteins. Here, we report the results of a NMR structural comparison between the native human p53 transactivation domain and an inactive mutant (22L,23W$\rightarrow$22R,23S). Results show that the mutant has an identical overall structural topology as the native protein, to the extent that the amphipathic helix formed by the residues 18T 26L within the native p53 transactivating domain is preserved in the double mutant. Therefore, the lack of transcriptional activity in the double mutant should be ascribed to the disruption of the essential hydrophobic contacts between the p53 transactivation domain and target proteins due to the (22L,23W$\rightarrow$22R,23S) mutation.

• Journal of Microbiology and Biotechnology
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• v.22 no.3
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• pp.378-384
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• 2012

In aquatic invertebrates, particularly marine gastropods, organotin compounds induce irreversible sexual abnormality in females, which is termed imposex, at very low concentrations. Organotin compounds are agonists for nuclear receptors such as RXRs and $PPAR{\gamma}$. However, the imposex phenomenon has not been reported to act as an antagonist on estrogen receptors in other species, including vertebrates and invertebrates. In order to gain insights into the antagonistic activity of organotin compounds on estrogen receptors (ERs), we examined the inhibitive effect of these compounds on estradiol-dependent ${\beta}$-galactosidase activity using the yeast two-hybrid detection system consisting of a combination of the human estrogen receptor ($hER{\beta}$) ligand-binding domain and the co-activator steroid receptor co-activator-1 (SRC1). Tributyltin-hydroxide (TBT-OH) and triphenyltin-chlorine (TPT-Cl) exhibited an inhibitive effect on $E_2$-dependent transcriptional activity, similar to antagonistic chemicals such as 4-hydroxytamoxifen (OHT) or ICI 182,780, at a very low concentration of $10^{-14}$ M TBT or $10^{-10}$ M TPT, respectively. The yeast growth and transcriptional activity with transcriptional factor GAL4 did not exhibit any effect at the tested concentration of TBT or TPT. Moreover, the yeast two-hybrid system using the interaction between p53 and the T antigen of SV40 large did not describe any effect at the tested concentration of OHT or ICI 182,780. However, the interaction between p53 and T antigen was inhibited at a TBT or TPT concentration of $10^{-9}$ M, respectively. These results indicate that TBT and TPT act as inhibitors of ER-dependent reporter gene transcriptional activation and of the interaction between $hER{\beta}$ LBD and the co-activator SRC1 in the yeast two-hybrid system. Consequently, our data could partly explain the occurrence of organotin compound-induced imposex on the endocrine system of mammals, including humans.

• BMB Reports
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• v.49 no.11
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• pp.587-589
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• 2016

The circadian clock system enables organisms to anticipate the rhythmic environmental changes and to manifest behavior and physiology at advantageous times of the day. Transcriptional/translational feedback loop (TTFL) is the basic feature of the eukaryotic circadian clock and is based on the rhythmic association of circadian transcriptional activator and repressor. In Drosophila, repression of dCLOCK/CYCLE (dCLK/CYC) mediated transcription by PERIOD (PER) is critical for inducing circadian rhythms of gene expression. Pacemaker neurons in the brain control specific circadian behaviors upon environmental timing cues such as light and temperature cycle. We show that amino acids 657-707 of dCLK are important for the transcriptional activation and the association with PER both in vitro and in vivo. Flies expressing dCLK lacking AA657-707 in $Clk^{out}$ genetic background, homologous to the mouse Clock allele where exon 19 region is deleted, display pacemaker-neuron-dependent perturbation of the molecular clockwork. The molecular rhythms in light-cycle-sensitive pacemaker neurons such as ventral lateral neurons ($LN_vs$) were significantly disrupted, but those in temperature-cycle-sensitive pacemaker neurons such as dorsal neurons (DNs) were robust. Our results suggest that the dCLK-controlled TTFL diversify in a pacemaker-neuron-dependent manner which may contribute to specific functions such as different sensitivities to entraining cues.

• Bulletin of the Korean Chemical Society
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• v.34 no.4
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• pp.1165-1169
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• 2013

To elucidate the role of PKG isoforms in transcriptional control of cyclin D1, we employed a series of expression vectors of PKG $1{\alpha}$ and PKG $1{\beta}$ which encode HA-tagged wild type and constitutively active (SD and ${\Delta}N$) mutants. Our present study demonstrates that both the constitutively active mutants of PKG $1{\beta}$ downregulate the transcription of cyclin D1 when transiently transfected in NIH3T3 cells, whereas PKG $1{\alpha}$ mutants show weak inhibition. We further studied the transcriptional regulators of cyclin D1, such as, c-fos, NF-${\kappa}B$, and CRE by using the luciferase reporter assay. Constitutively active mutants of PKG $1{\beta}$ showed marked transcriptional downregulation of c-fos in NIH3T3 cells, whereas PKG $1{\alpha}$ downregulated c-fos to a lesser extent. We also found that the constitutively active mutants of PKG negatively regulated the activation of NF-${\kappa}B$ and CRE, suggesting their involvement in the regulation of cyclin D1.

• IMMUNE NETWORK
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• v.23 no.1
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• pp.5.1-5.28
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• 2023

Th cell lineage determination and functional specialization are tightly linked to the activation of lineage-determining transcription factors (TFs) that bind cis-regulatory elements. These lineage-determining TFs act in concert with multiple layers of transcriptional regulators to alter the epigenetic landscape, including DNA methylation, histone modification and threedimensional chromosome architecture, in order to facilitate the specific Th gene expression programs that allow for phenotypic diversification. Accumulating evidence indicates that Th cell differentiation is not as rigid as classically held; rather, extensive phenotypic plasticity is an inherent feature of T cell lineages. Recent studies have begun to uncover the epigenetic programs that mechanistically govern T cell subset specification and immunological memory. Advances in next generation sequencing technologies have allowed global transcriptomic and epigenomic interrogation of CD4+ Th cells that extends previous findings focusing on individual loci. In this review, we provide an overview of recent genome-wide insights into the transcriptional and epigenetic regulation of CD4+ T cell-mediated adaptive immunity and discuss the implications for disease as well as immunotherapies.

• Toxicological Research
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• v.23 no.1
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• pp.19-24
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• 2007

We demonstrate that paclitaxel, an antitumor agent derived from yew tree, inhibits LPS- and $IFN-{\gamma}$-induced NF-kB/Rel activation in RAW 264.7 cells. Previously, paclitaxel ($>10{\mu}M$) has been known to induce iNOS gene expression in macrophages. However, in the previous report we described that the pretreatment of macrophages with low concentration of paclitaxel ($0.1{\mu}M$) for 8 h inhibited LPS-induced iNOS gene expression. Pretreatment of RAW 264.7 cells with paclitaxel significantly inhibited NF-kB/Rel transcriptional activation. Electrophoretic mobility shift assay further confirmed that pretreatment of macrophages with paclitaxel inhibited NF-kB/Rel DNA binding. Taxotere, a semisynthetic analog of paclitaxel, also inhibited LPS- and $IFN-{\gamma}$-induced iNOS gene expression. Collectively, these series of experiments indicate that paclitaxel inhibits iNOS gene expression by blocking NF-kB/Rel activation.

• The Korean Journal of Physiology and Pharmacology
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• v.18 no.5
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• pp.403-409
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• 2014

The Bis protein is known to be involved in a variety of cellular processes including apoptosis, migration, autophagy as well as protein quality control. Bis expression is induced in response to a number of types of stress, such as heat shock or a proteasome inhibitor via the activation of heat shock factor (HSF)1. We report herein that Bis expression is increased at the transcriptional level in HK-2 kidney tubular cells and A172 glioma cells by exposure to oxidative stress such as $H_2O_2$ treatment and oxygen-glucose deprivation, respectively. The pretreatment of HK-2 cells with N-acetyl cysteine, suppressed Bis induction. Furthermore, HSF1 silencing attenuated Bis expression that was induced by $H_2O_2$, accompanied by increase in reactive oxygen species (ROS) accumulation. Using a series of deletion constructs of the bis gene promoter, two putative heat shock elements located in the proximal region of the bis gene promoter were found to be essential for the constitutive expression is as well as the inducible expression of Bis. Taken together, our results indicate that oxidative stress induces Bis expression at the transcriptional levels via activation of HSF1, which might confer an expansion of antioxidant capacity against pro-oxidant milieu. However, the possible role of the other cis-element in the induction of Bis remains to be determined.

• BMB Reports
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• v.51 no.8
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• pp.388-393
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• 2018

The activating transcription factor (ATF) 4 belongs to the ATF/CREB (cAMP Response Element Binding bZIP [Basic Leucine Zipper]) transcription factor family, and plays a central role in the UPR (Unfolded Protein Response) process in cells. The induction of ATF4 expression has previously been shown to increase the replication of HIV-1. However, the detailed mechanism underlying this effect and the factors involved in the regulation of ATF4 function are still unknown. Here, we demonstrate first that knocking out ATF4 using siRNA shows a strong negative effect on HIV-1 production, indicating that ATF4 is a functional positive cellular factor in HIV-1 production. To determine the mechanism by which ATF4 regulates the HIV-1 life cycle, we assessed the effect of the overexpression of wild type ATF4 and its various derivatives on HIV-1 LTR-mediated transcriptional activation and the production of HIV-1 particles. This effect was studied through co-transfection experiments with either reporter vectors or proviral DNA. We found that the N-terminal domains of ATF4 are involved in HIV-1 LTR-mediated transcriptional activation, and thus in HIV-1 production.

• Journal of Physiology & Pathology in Korean Medicine
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• v.19 no.1
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• pp.196-203
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• 2005

Gunggui-tang has been used for the therapy of blood disorders in Hangbang medicine for long time. Also, Glycyrrhiza uralensis has been used for deficientblood patterns with an irregular pulse or palpitations, coughing and wheezing, and heat or cold in the lungs. Melanogenesis is a physiological process resulting in the synthesis of melanin pigments. We investigated whether the water extract of Gunggui-tang plus G. uralensis inhibited melanogenesis in B16 melanoma cells. Because the molecular events connecting the regulation in tyrosinase activity remain to be elucidated, we also aimed to determine whether Gunggui-tang gamibang(GTG) affects tyrosinase at the gene activation level in the cells. First, we showed that GTG inhibited the tyrosinase promoter activity and further, down-regulated the tyrosinase protein activity in ${\alpha}-melanocyte-stimulating$ hormone $({\alpha}-MSH)-treated$ B16 melanoma cells. GTG also resulted in a decrease of melanin content in MSH-induced melanogenesis, indicating that GTG may be a useful drug in studying the regulation of melanogenesis. The pretreatment of GTG significantly prevented phosphotransferase activity of c-Jun N-terminal kinase (JNK1) and transcriptional activation of activating protein-1 (AP-1) in MSH-treated B16 melanoma cells. These findings indicate that GTG inhibits melanogenesis of B16 melanoma cells via suppression of phosphotransferase activity of JNK1 and transcriptional activation of AP-1.

• Journal of Microbiology and Biotechnology
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• v.25 no.2
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• pp.255-267
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• 2015

Mycobacterium avium subsp. paratuberculosis (MAP) is the causative agent of Johne's disease, a chronic debilitating disease affecting ruminants worldwide. In the present study, we aimed to determine the major gene networks and pathways underlying the immune response to MAP infection using whole-blood cells, as well as provide the potential transcriptional markers for identifying the status of MAP infection. We analyzed the transcriptional profiles of whole-blood cells of cattle identified and grouped according to the presence of MAP-specific antibodies and the MAP shed by them. The grouping was based on the results obtained by ELISA and PCR analyses as follows: i) Test1 group: MAP-negative results obtained by ELISA and positive results obtained by PCR; ii) Test2 group: MAP-positive results obtained by ELISA and negative results obtained by PCR; iii) Test3 group: MAP-positive results obtained by ELISA and positive results obtained by PCR; iv) uninfected control: MAP-negative results obtained both by ELISA and PCR analysis. The results showed down-regulated production and metabolism of reactive oxygen species in the Test1 group, activation of pathways related to the host-defense response against MAP (LXR/RXR activation and complement system) in the Test2 and Test3 groups, and anti-inflammatory response (activation of IL-10 signaling pathway) only in the Test3 group. Our data indicate a balanced response that serves the immune-limiting mechanism while the host-defense responses are progressing.