• Journal of Microbiology
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• 제35권4호
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• pp.315-322
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• 1997

The effects of a polyamine, spermine, on the differentiation of Naegleria gruberi amebas into flagellates were tested. Addition of spermine at early stages of differentiation (until 40 min after the initiation of differentiation) completely inhibited the differentiation. To understand the inhibition mechanism, we examined the effect of spermine treatment on the transcription and translation of differentiation-specific genes during differentiation. Addition of spermine at early stages did not inhibit the accumulation of two differentiation-specific mRNAs, ${\alpha}$-tubulin and Class I mRNA, significantly, but rather prevented the rapid degradation of the mRNAs in later overall protein synthesis partially and gradually. However, translation of the ${\alpha}$-tubulin mRNA was completely inhibited. These data suggest that the inhibition of differentiation of N. gruberi by spermine treatment did not result from the inhibition of transcription of differentiation-specific genes but from the specific inhibition of translation of the mRNAs during the differentiation.

• BMB Reports
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• 제53권2호
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• pp.94-99
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• 2020

Brain cytoplasmic 200 RNA (BC200 RNA) is proposed to act as a local translational modulator by inhibiting translation after being targeted to neuronal dendrites. However, the mechanism by which BC200 RNA inhibits translation is not fully understood. Although a detailed functional analysis of RNA motifs is essential for understanding the BC200 RNA-mediated translation-inhibition mechanism, there is little relevant research on the subject. Here, we performed a systematic domain-dissection analysis of BC200 RNA to identify functional RNA motifs responsible for its translational-inhibition activity. Various RNA variants were assayed for their ability to inhibit translation of luciferase mRNA in vitro. We found that the 111-200-nucleotide region consisting of part of the Alu domain as well as the A/C-rich domain (consisting of both the A-rich and C-rich domains) is most effective for translation inhibition. Surprisingly, we also found that individual A-rich, A/C-rich, and Alu domains can enhance translation but at different levels for each domain, and that these enhancing effects manifest as cap-dependent translation.

• BMB Reports
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• 제50권11호
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• pp.539-545
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• 2017

The Integrated Stress Response (ISR) refers to a signaling pathway initiated by stress-activated $eIF2{\alpha}$ kinases. Once activated, the pathway causes attenuation of global mRNA translation while also paradoxically inducing stress response gene expression. A detailed analysis of this pathway has helped us better understand how stressed cells coordinate gene expression at translational and transcriptional levels. The translational attenuation associated with this pathway has been largely attributed to the phosphorylation of the translational initiation factor $eIF2{\alpha}$. However, independent studies are now pointing to a second translational regulation step involving a downstream ISR target, 4E-BP, in the inhibition of eIF4E and specifically cap-dependent translation. The activation of 4E-BP is consistent with previous reports implicating the roles of 4E-BP resistant, Internal Ribosome Entry Site (IRES) dependent translation in ISR active cells. In this review, we provide an overview of the translation inhibition mechanisms engaged by the ISR and how they impact the translation of stress response genes.

• BMB Reports
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• 제30권1호
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• pp.55-59
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• 1997

The heat shock response is a universal stress response observed in all organisms and cultured cells. The response is regulated at both the transcriptional and translational level. Heat shocked Drosophila melanogaster Kc cells are used as the system for the study of translational regulation. In this system non-heat shock messages are associated with polysome but are not translated in a heat shocked condition. To figure out the change in the translation machinery. the effects of translation elongation inhibitors were tested on Kc cells. The result showed that the sensitivity of translation to these drugs changed in heat shocked cells. The significant changes were the decreased inhibition of heat shock protein synthesis by cycloheximide, emetine. and puromycin. and the increased inhibition of heat shock protein synthesis by verrucarin A. implying that the translation elongation mechanism in heat shocked cells changed.

• Molecules and Cells
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• 제42권6호
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• pp.495-500
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• 2019

Brain cytoplasmic 200 RNA (BC200 RNA), originally identified as a neuron-specific non-coding RNA, is also observed in various cancer cells that originate from non-neural cells. Studies have revealed diverse functions of BC200 RNA in cancer cells. Accordingly, we hypothesized that BC200 RNA might be modified in cancer cells to generate cancerous BC200 RNA responsible for its cancer-specific functions. Here, we report that BC200 RNA sequences are highly heterogeneous in cancer cells by virtue of multiple adenine nucleotide insertions in the internal A-rich region. The insertion of adenine nucleotides enhances BC200 RNA-mediated translation inhibition, possibly by increasing the binding affinity of BC200 RNA for eIF4A (eukaryotic translation initiation factor 4A).

• 한국미생물·생명공학회지
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• 제38권1호
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• pp.64-69
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• 2010

본 실험은 Propolis ethanol 추출물과, chloroform, ethyl acetate, butanol 등 4가지 용매로 더 추출한 분획틀을 이용하여 DPPH radical 소거능 실험과 항진균활성을 알아보았고, 고체배지 및 액체배지에서 항진균활성을 측정하였다. 또한 luciferase mRNA를 이용한 in vitro translation으로 이들 추출물에 의한 단백질합성에의 영향을 검토하였다. 첫 번째로, 액체배지에서의 항진균 활성을 실험한 결과 Candida glabrata, Candida lusitaniae 그리고 Cryptococcos neoformans 등의 성장저해율이 chloroform 분획 존재하에서 각각 39%, 41%, 48% 이었으며 ethyl acetate 분획 존재하에서 각각 25%, 24%, 13%로 측정되었다. 이 결과는 ethyl acetate 분획에 비해 chloroform 분획에 진균 성장 저해물질이 가장 많이 존재함을 나타낸다. 두 번째로, 동일한 비율로 희석한 프로폴리스 분획물들과 합성 항산화제인 BHT의 수소공여능을 비교하였을 때 Ethanol 추출물의 수소공여능은 합성항산화제인 0.1% BHT의 수소공여능보다 높았으며, 분획들 중에서 chloroform 분획이 가장 수소공여능이 높았다. 세 번째로, luciferase mRNA를 이용한 in vitro, translation 실험에서는 Propoliis ethanol 추출물이 단백질합성을 저해하는 것으로 관찰되었다. Propolis 분획물들 중에서 chloroform 분획이 단백질 합성을 가장 많이 저해하였다. 이와 같은 결과는 chloroform 분획물이 다른 분획에 비해 수소공여능, 진균성장 저해율 및 단백질합성 저해활성이 가장 큰 것으로 보여지므로 이 분획물에 대한 생화학적인 연구가 요구된다.

• Molecules and Cells
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• 제43권3호
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• pp.304-311
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• 2020

Methionyl-tRNA synthetase (MRS) is essential for translation. MRS mutants reduce global translation, which usually increases lifespan in various genetic models. However, we found that MRS inhibited Drosophila reduced lifespan despite of the reduced protein synthesis. Microarray analysis with MRS inhibited Drosophila revealed significant changes in inflammatory and immune response genes. Especially, the expression of anti-microbial peptides (AMPs) genes was reduced. When we measured the expression levels of AMP genes during aging, those were getting increased in the control flies but reduced in MRS inhibition flies age-dependently. Interestingly, in the germ-free condition, the maximum lifespan was increased in MRS inhibition flies compared with that of the conventional condition. These findings suggest that the lifespan of MRS inhibition flies is reduced due to the down-regulated AMPs expression in Drosophila.

• Journal of Plant Biotechnology
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• 제38권1호
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• pp.87-93
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• 2011

SAMDC는 폴리아민 생합성 과정에서 주효소로 작용하며 항상성을 유지하기위해 정교하게 조절된다. 카네이션 SAMDC 유전자는 5'-leader sequence에 54개 아미노산으로 구성된 small uORF가 존재한다. Translation 과정을 조절하는 uORF의 작용기작을 연구하기 위하여 35S 프로모터에 SAMDC 유전자의 uORF 부위와 GUS 유전자를 재조합한 형질전환 담배 식물체를 이용하였다. 본 실험에서는 SAMDC uORF 염기서열 혹은 SAMDC uORF 단백질에 의해서 downstream GUS ORF의 translation이 억제되었다. 특히 translation 억제는 개시코돈이 point-mutation된 construct에서 효과적으로 이루어졌다. 따라서 이러한 결과는 ribosomal stalling이 translation 억제 과정에 관여한 것으로 사료된다. 개시 코돈과 종결코돈을 가진 SAMDC uORF의 아미노산 서열을 frame shift 시키면 GUS 활성이 증가하였는데 이는 translation inhibitor로서 작용할 때 아미노산 서열이 중요하다는 것을 의미하며, 결국은 SAMDC uORF의 단백질 구조가 중요하게 작용할 가능성을 제시한다. 또한 유식물과 담배 꽃 등의 in vivo 상에서도 GUS 발현을 조직화학적으로 분석했을 때 small uORF가 존재할 경우 GUS 염색이 크게 저하되었지만, 개시코돈이나 혹은 종결코돈이 제거되도록 point-mutation 시킨 construct가 도입된 형질전환식물체에서는 SAMDC uORF의 억제효과가 크게 완화 되었다. 또한 가장 중요한 관찰 결과로는 small uORF 염기서열로부터 in vitro 시스템에서 5.7 kDa의 단백질이 실제적으로 합성되었음을 관찰하였다. 폴리아민 처리 후 GUS 단백질이 억제된 결과는 uORF로부터 합성된 단백질이 폴리아민 뿐 만 아니라 translation 과정에 관여하는 다른 요소들과 상호작용을 이루어 조절될 수 있음을 암시한다.

• The Korean Journal of Physiology and Pharmacology
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• 제13권2호
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• pp.131-138
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• 2009

The binding of interleukin-6 (IL-6) cytokine family ligands to the gp130 receptor complex activates the Janus kinase (JAK)/ signal transducer and activator of transcription 3 (STAT3) signal transduction pathway, where STA T3 plays an important role in cell survival and tumorigenesis. Constitutive activation of STAT3 has been frequently observed in many cancer tissues, and thus, blocking of the gp130 signaling pathway, at the JAK level, might be a useful therapeutic approach for the suppression of STAT3 activity, as anticancer therapy. AG490 is a tyrphostin tyrosine kinase inhibitor that has been extensively used for inhibiting JAK2 in vitro and in vivo. In this study, we demonstrate a novel mechanism associated with AG490 that inhibits the JAK/STAT3 pathway. AG490 induced downregulation of gp130, a common receptor for the IL-6 cytokine family compounds, but not JAK2 or STAT3, within three hours of exposure. The downregulation of gp130 was not caused by enhanced degradation of gp130 or by inhibition of mRNA transcription. It most likely occurred by translation inhibition of gp130 in association with phosphorylation of the eukaryotic initiation factor-2 a. The inhibition of protein synthesis of gp130 by AG490 led to immediate loss of mature gp130 in cell membranes, due to its short half-life, thereby resulting in reduction in the STAT3 response to IL-6. Taken together, these results suggest that AG490 blocks the STAT3 activation pathway via a novel pathway.

• BMB Reports
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• 제49권4호
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• pp.199-200
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• 2016

Gene regulation in the brain is essential for long-term plasticity and memory formation. Despite this established notion, the quantitative translational map in the brain during memory formation has not been reported. To systematically probe the changes in protein synthesis during memory formation, our recent study exploited ribosome profiling using the mouse hippocampal tissues at multiple time points after a learning event. Analysis of the resulting database revealed novel types of gene regulation after learning. First, the translation of a group of genes was rapidly suppressed without change in mRNA levels. At later time points, the expression of another group of genes was downregulated through reduction in mRNA levels. This reduction was predicted to be downstream of inhibition of ESR1 (Estrogen Receptor 1) signaling. Overexpressing Nrsn1, one of the genes whose translation was suppressed, or activating ESR1 by injecting an agonist interfered with memory formation, suggesting the functional importance of these findings. Moreover, the translation of genes encoding the translational machineries was found to be suppressed, among other genes in the mouse hippocampus. Together, this unbiased approach has revealed previously unidentified characteristics of gene regulation in the brain and highlighted the importance of repressive controls.