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Cha, Seho,Choe, Joonho,Seo, Taegun Elsevier 2016 Biochemical and biophysical research communication Vol.479 No.4
<P><B>Abstract</B></P> <P>Kaposi's sarcoma-associated herpesvirus (KSHV) is an etiological agent of Kaposi's sarcoma and primary effusion lymphoma. Like other herpesviruses, KSHV has two distinct life cycles: latent and lytic. Among KSHV latent genes, viral interferon regulatory factor 3 (vIRF3), which shares homology with cellular IRFs, is a multifunctional protein. To identify unknown functions of vIRF3, we performed luciferase-reporter assays in the presence of vIRF3. These analyses revealed that overexpression of vIRF3 inhibited T-cell factor (TCF)-dependent transcriptional activity. This TCF-dependent transcription was associated with the Wnt signaling pathway, which normally regulates embryonic development, but contributes to oncogenesis under dysregulated conditions. Using a mutagenesis analysis, we identified a CREB-binding protein-interaction motif (LXXLL) in vIRF3 as an important region for its inhibitory activity. Collectively, our findings provide insight into the dysregulation of host signaling pathways in KSHV-infected cells.</P> <P><B>Highlights</B></P> <P> <UL> <LI> vIRF3 inhibits the Wnt signaling pathway. </LI> <LI> vIRF2 does not affect cellular localization of β-catenin. </LI> <LI> The LXXLL motif of vIRF3 is important for inhibition of TCF-dependent transcription. </LI> </UL> </P>
Kwanghoon Kim,Mun Seok Choe,Woosang Lee,Joonho So,Eunmi Choi IEEE 2014 IEEE transactions on plasma science Vol.42 No.4
<P>This paper reports the estimation of the electric field from a large aperture cavity that generates a higher order mode by backpropagation of fields measured in free space. A higher order mode of a TE<SUB>6,2</SUB> mode at 94 GHz is designed and fabricated using a quasi-optical manner for the analysis. The backpropagating field at the aperture is compared with the measured field. The field estimated at the aperture is used to analyze the mode information, such as the amount of mode mixture of two different rotating fields and the phase difference between two modes. This paper provides a quantitative way to analyze the rotating cylindrical modes generated from an oversized cavity.</P>
Rnf152 Is Essential for NeuroD Expression and Delta-Notch Signaling in the Zebrafish Embryos
Kumar, Ajeet,Huh, Tae-Lin,Choe, Joonho,Rhee, Myungchull Korean Society for Molecular and Cellular Biology 2017 Molecules and cells Vol.40 No.12
We report the biological functions of a zebrafish homologue of RING-finger protein 152 (rnf152) during embryogenesis. rnf152 was initially identified as a brain-enriched E3 ligase involved in early embryogenesis of zebrafish. Expression of rnf152 was ubiquitous in the brain at 24 hpf but restricted to the eyes, midbrain-hindbrain boundary (MHB), and rhombomeres at 48 hpf. Knockdown of rnf152 in zebrafish embryos caused defects in the eyes, MHB, and rhombomeres (r1-7) at 24 hpf. These defects in rnf152-deficient embryos were analyzed by whole-mount in situ hybridization (WISH) using neuroD, deltaD, notch1a, and notch3 probes. NeuroD expression was abolished in the marginal zone, outer nuclear layer (ONL), inner nuclear layer (INL), and ganglion cell layer (GCL) of the eyes at 27 hpf. Furthermore, deltaD and notch1a expression was remarkably reduced in the ONL, INL, subpallium, tectum, cerebellum, and rhombomeres (r1-7) at 24 hpf, whereas notch3 expression was reduced in the tectum, cerebellum, and rhombomeres at 24 hpf. Finally, we confirmed that expression of Notch target genes, her4 and ascl1a, also decreased significantly in these areas at 24 hpf. Thus, we propose that Rnf152 is essential for development of the eyes, midbrain and hindbrain, and that Delta-Notch signaling is involved.
Kim, Juwon,Lee, Soo Hyeon,Choe, Joonho,Park, Tae Gwan John Wiley Sons, Ltd. 2009 The journal of gene medicine Vol.11 No.9
<B>Background</B><P>A variety of synthetic carriers, such as cationic polymers and lipids, have been used as nonviral carriers for small interfering RNA (siRNA) delivery. Although siRNA polyplexes and lipoplexes exhibited good gene silencing efficiencies, they often showed serious cytotoxicities, which are not useful for clinical applications. A double-stranded RNA binding cellular protein with highly specific siRNA binding property and noncytotoxicity was used for siRNA delivery.</P><B>Methods</B><P>A double-stranded RNA binding domain (dsRBD) of human double-stranded RNA activated protein kinase R was genetically produced and utilized to complex siRNA for intracellular delivery. For characterization of the siRNA/dsRBD complexes, decomplexation assay and RNase protection assay were performed. Cytotoxicity and target gene inhibition ability were also examined using human carcinoma cell lines.</P><B>Results</B><P>The recombinantly produced polypeptide dsRBD exhibited its inherent binding activity for siRNA without sequence specificity, and the siRNA/dsRBD complexes protected siRNA from degradation by ribonucleases. Green fluorescent protein (GFP) siRNA/dsRBD complexes showed prominent down-regulation of a target GFP gene, when an endosomal escape function was supplemented by addition of a fusogenic peptide, KALA, in the formulation.</P><B>Conclusions</B><P>The results suggest that dsRBD-based protein carriers could be successfully applied for a wide range of therapeutic siRNAs for intracellular gene inhibition without showing any cytotoxicity. Copyright © 2009 John Wiley & Sons, Ltd.</P>
Park, Junsoo,Seo, Taegun,Kim, Hakzoo,Choe, Joonho American Society for Microbiology 2005 Molecular and cellular biology Vol.25 No.18
<B>ABSTRACT</B><P>Replication protein A (RPA) is a single-stranded-DNA-binding protein composed of three subunits with molecular masses of 70, 32, and 14 kDa. The protein is involved in multiple processes of eukaryotic DNA metabolism, including DNA replication, repair, and recombination. In <I>Xenopus</I>, <I>Xenopus</I> RPA-interacting protein α has been identified as a carrier molecule of RPA into the nucleus. In this study, human RPA-interacting protein α (hRIPα) and five novel splice isoforms (named hRIPα, hRIPβ, hRIPγ, hRIPδ1, hRIPδ2, and hRIPδ3 according to the lengths of their encoding peptides) were cloned. Among hRIP isoforms, hRIPα and hRIPβ were found to be the major splice isoforms and to show different subcellular localizations. While hRIPα localized to the cytoplasm, hRIPβ was found in the PML nuclear body. Modification of hRIPβ by sumoylation was found to be required for localization to the PML nuclear body. The results of the present work demonstrate that hRIPβ transports RPA into the PML nuclear body and releases RPA upon UV irradiation. hRIPβ thus plays an important role in RPA deposition in PML nuclear bodies and thereby supplements RPA for DNA metabolism.</P>
Ri, Hwajung,Lee, Jongbin,Sonn, Jun Young,Yoo, Eunseok,Lim, Chunghun,Choe, Joonho Korean Society for Molecular and Cellular Biology 2019 Molecules and cells Vol.42 No.4
Post-transcriptional regulation underlies the circadian control of gene expression and animal behaviors. However, the role of mRNA surveillance via the nonsense-mediated mRNA decay (NMD) pathway in circadian rhythms remains elusive. Here, we report that Drosophila NMD pathway acts in a subset of circadian pacemaker neurons to maintain robust 24 h rhythms of free-running locomotor activity. RNA interference-mediated depletion of key NMD factors in timeless-expressing clock cells decreased the amplitude of circadian locomotor behaviors. Transgenic manipulation of the NMD pathway in clock neurons expressing a neuropeptide PIGMENT-DISPERSING FACTOR (PDF) was sufficient to dampen or lengthen free-running locomotor rhythms. Confocal imaging of a transgenic NMD reporter revealed that arrhythmic Clock mutants exhibited stronger NMD activity in PDF-expressing neurons than wild-type. We further found that hypomorphic mutations in Suppressor with morphogenetic effect on genitalia 5 (Smg5) or Smg6 impaired circadian behaviors. These NMD mutants normally developed PDF-expressing clock neurons and displayed daily oscillations in the transcript levels of core clock genes. By contrast, the loss of Smg5 or Smg6 function affected the relative transcript levels of cAMP response element-binding protein B (CrebB) in an isoform-specific manner. Moreover, the overexpression of a transcriptional repressor form of CrebB rescued free-running locomotor rhythms in Smg5-depleted flies. These data demonstrate that CrebB is a rate-limiting substrate of the genetic NMD pathway important for the behavioral output of circadian clocks in Drosophila.
The DOUBLETIME protein kinase regulates phosphorylation of the <i>Drosophila</i> PDP1&egr;
Choi, Changtaek,Lee, Jongbin,Lim, Chunghun,Jang, Donghoon,Choe, Joonho Blackwell Publishing Ltd 2009 Journal of Neurochemistry Vol.111 No.1
<P>Abstract</P><P>Reversible phosphorylation of clock proteins plays an important role in circadian timekeeping as it is a key post-translational mechanism that regulates the activity, stability and subcellular localization of core clock proteins. The kinase DOUBLETIME (DBT), a <I>Drosophila</I> ortholog of mammalian casein kinase I&egr;, regulates circadian phosphorylation of two essential clock proteins, PERIOD and dCLOCK. We present evidence that <I>Par Domain Protein 1&egr;</I> (PDP1&egr;), a transcription factor and mediator of clock output in <I>Drosophila</I>, is phosphorylated <I>in vivo</I> and in cultured cells by DBT activity. We also demonstrate that DBT interacts with PDP1&egr; and promotes its degradation by the ubiquitin-proteasome pathway in cultured cells. In addition, PDP1&egr; nuclear localization is decreased by <I>dbt</I> RNA interference in S2 cell system. These results suggest that DBT regulates phosphorylation, stability and localization of PDP1&egr;, and that it has multiple targets in the <I>Drosophila</I> circadian system.</P>