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  • MinireviewJanuary 31, 2014

    38 412 1763

    The Dharma of Nonsense-Mediated mRNA Decay in Mammalian Cells

    Maximilian Wei-Lin Popp, and Lynne E. Maquat

    Mol. Cells 2014; 37(1): 1-8 https://doi.org/10.14348/molcells.2014.2193
    Abstract

    Abstract : Mammalian-cell messenger RNAs (mRNAs) are generated in the nucleus from precursor RNAs (pre-mRNAs, which often contain one or more introns) that are complexed with an array of incompletely inventoried proteins. During their biogenesis, pre-mRNAs and their derivative mRNAs are subject to extensive cis-modifications. These modifications promote the binding of distinct polypeptides that mediate a diverse array of functions needed for mRNA metabolism, including nuclear export, inspection by the nonsense-mediated mRNA decay (NMD) quality-control machinery, and synthesis of the encoded protein product. Ribonucleoprotein complex (RNP) remodeling through the loss and gain of protein constituents before and after pre-mRNA splicing, during mRNA export, and within the cytoplasm facilitates NMD, ensuring integrity of the transcriptome. Here we review the mRNP rearrangements that culminate in detection and elimination of faulty transcripts by mammalian-cell NMD.

  • MinireviewJanuary 31, 2014

    28 370 1374

    Abstract : ADP-ribosylation is a type of posttranslational modification catalyzed by members of the poly(ADP-ribose) (PAR) polymerase superfamily. ADP-ribosylation is initiated by PARPs, recognized by PAR binding proteins, and removed by PARG and other ADP-ribose hydrolases. These three groups of proteins work together to regulate the cellular and molecular response of PAR signaling, which is critical for a wide range of cellular and physiological functions.

  • Research ArticleJanuary 31, 2014

    15 311 490

    Specificity Protein 1 Expression Contributes to Bcl-w-Induced Aggressiveness in Glioblastoma Multiforme

    Woo Sang Lee, Junhye Kwon, Dong Ho Yun, Young Nam Lee, Eun Young Woo, Myung-Jin Park, Jae-Seon Lee, Young-Hoon Han, and In Hwa Bae

    Mol. Cells 2014; 37(1): 17-23 https://doi.org/10.14348/molcells.2014.2161
    Abstract

    Abstract : We already had reported that Bcl-w promotes invasion or migration in gastric cancer cells and glioblastoma multiforme (GBM) by activating matrix metalloproteinase-2 (MMP-2) specificity protein 1 (Sp1) or β-cateinin, respectively. High expression of Bcl-w also has been reported in GBM which is the most common malignant brain tumor and exhibits aggressive and invasive behavior. These reports propose that Bcl-w-induced signaling is strongly associated with aggressive characteristic of GBM. We demonstrated that Sp1 protein or mRNA expression is induced by Bcl-w using Western blotting or RT-PCR, respectively, and markedly elevated in high-grade glioma specimens compared with low-grade glioma tissues using tissue array. However, relationship between Bcl-w-related signaling and aggressive characteristic of GBM is poorly characterized. This study suggested that Bcl-w-induced Sp1 activation promoted expression of glioma stem-like cell markers, such as Musashi, Nanog, Oct4 and sox-2, as well as neurosphere formation and invasiveness, using western blotting, neurosphere formation assay, or invasion assay, culminating in their aggressive behavior. Therefore, Bcl-w-induced Sp1 activation is proposed as a putative marker for aggressiveness of GBM.

  • Research ArticleJanuary 31, 2014

    7 310 661

    Impaired Extinction of Learned Contextual Fear Memory in Early Growth Response 1 Knockout Mice

    Seungrie Han, Soontaek Hong, Jiwon Mo, Dongmin Lee, Eunju Choi, June-seek Choi, Woong Sun, Hyun Woo Lee, and Hyun Kim

    Mol. Cells 2014; 37(1): 24-30 https://doi.org/10.14348/molcells.2014.2206
    Abstract

    Abstract : Inductive expression of early growth response 1 (Egr-1) in neurons is associated with many forms of neuronal activity. However, only a few Egr-1 target genes are known in the brain. The results of this study demonstrate that Egr-1 knockout (KO) mice display impaired contextual extinction learning and normal fear acquisition relative to wild-type (WT) control animals. Genome-wide microarray experiments revealed 368 differentially expressed genes in the hippocampus of Egr-1 WT exposed to different phases of a fear conditioning paradigm compared to gene expression profiles in the hippocampus of KO mice. Some of genes, such as serotonin receptor 2C (Htr2c), neuropeptide B (Npb), neuronal PAS domain protein 4 (Npas4), NPY receptor Y1 (Npy1r), fatty acid binding protein 7 (Fabp7), and neuropeptide Y (Npy) are known to regulate processing of fearful memories, and promoter analyses demonstrated that several of these genes contained Egr-1 binding sites. This study provides a useful list of potential Egr-1 target genes which may be regulated during fear memory processing.

  • Research ArticleJanuary 31, 2014

    3 229 663

    Ground-State Conditions Promote Robust Prdm14 Reactivation and Maintain an Active Dlk1-Dio3 Region during Reprogramming

    Omer Habib, Gizem Habib, Sung-Hwan Moon, Ki-Sung Hong, Jeong Tae Do, Youngsok Choi, Sung Woon Chang, and Hyung-Min Chung

    Mol. Cells 2014; 37(1): 31-35 https://doi.org/10.14348/molcells.2014.2212
    Abstract

    Abstract : Induced pluripotent stem cells (iPSCs) are capable of unlimited self-renewal and can give rise to all three germ layers, thereby providing a new platform with which to study mammalian development and epigenetic reprogramming. However, iPSC generation may result in subtle epigenetic variations, such as the aberrant methylation of the Dlk1-Dio3 locus, among the clones, and this heterogeneity constitutes a major drawback to harnessing the full potential of iPSCs. Vitamin C has recently emerged as a safeguard to ensure the normal imprinting of the Dlk1-Dio3 locus during reprogramming. Here, we show that vitamin C exerts its effect in a manner that is independent of the reprogramming kinetics. Moreover, we demonstrate that reprogramming cells under 2i conditions leads to the early upregulation of Prdm14, which in turn results in a highly homogeneous population of authentic pluripotent colonies and prevents the abnormal silencing of the Dlk1-Dio3 locus.

  • Research ArticleJanuary 31, 2014

    60 375 1502

    Genome-Wide SNP Calling Using Next Generation Sequencing Data in Tomato

    Ji-Eun Kim, Sang-Keun Oh, Jeong-Hee Lee, Bo-Mi Lee, and Sung-Hwan Jo

    Mol. Cells 2014; 37(1): 36-42 https://doi.org/10.14348/molcells.2014.2241
    Abstract

    Abstract : The tomato ( L.) is a model plant for genome research in , as well as for studying crop breeding. Genome-wide single nucleotide polymorphisms (SNPs) are a valuable resource in genetic research and breeding. However, to do discovery of genome-wide SNPs, most methods require expensive high-depth sequencing. Here, we describe a method for SNP calling using a modified version of SAMtools that improved its sensitivity. We analyzed 90 Gb of raw sequence data from next-generation sequencing of two resequencing and seven transcriptome data sets from several tomato accessions. Our study identified 4,812,432 non-redundant SNPs. Moreover, the workflow of SNP calling was improved by aligning the reference genome with its own raw data. Using this approach, 131,785 SNPs were discovered from transcriptome data of seven accessions. In addition, 4,680,647 SNPs were identified from the genome of , which are 60 times more than 71,637 of the PI212816 transcriptome. SNP distribution was compared between the whole genome and transcriptome of . Moreover, we surveyed the location of SNPs within genic and intergenic regions. Our results indicated that the sufficient genome-wide SNP markers and very sensitive SNP calling method allow for application of marker assisted breeding and genome-wide association studies.

  • Research ArticleJanuary 31, 2014

    60 409 1237

    HIF-1-Dependent Induction of Jumonji Domain-Containing Protein (JMJD) 3 under Hypoxic Conditions

    Ho-Youl Lee, Kang Choi, Hookeun Oh, Young-Kwon Park, and Hyunsung Park

    Mol. Cells 2014; 37(1): 43-50 https://doi.org/10.14348/molcells.2014.2250
    Abstract

    Abstract : Jumonji domain-containing proteins (JMJD) catalyze the oxidative demethylation of a methylated lysine residue of histones by using O, α-ketoglutarate, vitamin C, and Fe(II). Several JMJDs are induced by hypoxic stress to compensate their presumed reduction in catalytic activity under hypoxia. In this study, we showed that an H3K27me3 specific histone demethylase, JMJD3 was induced by hypoxia-inducible factor (HIF)-1α/β under hypoxia and that treatment with Clioquinol, a HIF-1α activator, increased JMJD3 expression even under normoxia. Chromatin immunoprecipitation (ChIP) analyses showed that both HIF-1α and its dimerization partner HIF-1β/Arnt occupied the first intron region of the mouse gene, whereas the HIF-1α/β heterodimer bound to the upstream region of the human , indicating that human and mouse have hypoxia-responsive regulatory regions in different locations. This study shows that both mouse and human are induced by HIF-1.

  • Research ArticleJanuary 31, 2014

    13 414 798

    Nucleolar GTPase NOG-1 Regulates Development, Fat Storage, and Longevity through Insulin/IGF Signaling in

    Young-Il Kim, Jaya Bandyopadhyay, Injeong Cho, Juyeon Lee, Dae Ho Park, and Jeong Hoon Cho

    Mol. Cells 2014; 37(1): 51-57 https://doi.org/10.14348/molcells.2014.2251
    Abstract

    Abstract : NOG1 is a nucleolar GTPase that is critical for 60S ribosome biogenesis. Recently, NOG1 was identified as one of the downstream regulators of target of rapamycin (TOR) in yeast. It is reported that TOR is involved in regulating lifespan and fat storage in . Here, we show that the ortholog (T07A9.9: ) in regulates growth, development, lifespan, and fat metabolism. A green fluorescence protein (GFP) promoter assay revealed ubiquitous expression of from the early embryonic to the adult stage. Furthermore, the GFP-tagged NOG-1 protein is localized to the nucleus, whereas the aberrant NOG-1 protein is concentrated in the nucleolus. Functional studies of NOG-1 in further revealed that knockdown resulted in smaller broodsize, slower growth, increased life span, and more fat storage. Moreover, over-expression resulted in decreased life span. Taken together, our data suggest that in may be an important player in regulating life span and fat storage the insulin/IGF pathway.

  • Research ArticleJanuary 31, 2014

    7 288 456
    Abstract

    Abstract : Eph receptors and their ligands ephrins have been implicated in guiding the directed migration of neural crest cells (NCCs). In this study, we found that Wnt1-Cre-mediated expression of ephrinA5-Fc along the dorsal midline of the dien- and mesencephalon resulted in severe craniofacial malformation of mouse embryo. Interestingly, expression of cephalic NCC markers decreased significantly in the frontonasal process and branchial arches 1 and 2, which are target areas for the migratory cephalic NCCs originating in the dien- and mesencephalon. In addition, these craniofacial tissues were much smaller in mutant embryos expressing ephrinA5-Fc. Importantly, EphA7-positive cephalic NCCs were absent along the dorsal dien- and mesencephalon of mutant embryos expressing ephrinA5-Fc, suggesting that the generation of cephalic NCCs is disrupted due to ephrinA5-Fc expression. NCC explant experiments suggested that ephrinA5-Fc perturbed survival of cephalic NCC precursors in the dorsal midline tissue rather than affecting their migratory capacity, which was consistent with our previous report that expression of ephrinA5-Fc in the dorsal midline is responsible for severe neuroepithelial cell apoptotic death. Taken together, our findings strongly suggest that expression of ephrinA5-Fc decreases a population of cephalic NCC precursors in the dorsal midline of the dien- and mesencephalon, thereby disrupting craniofacial development in the mouse embryos.

  • Research ArticleJanuary 31, 2014

    41 382 945

    Myeloid-Derived Suppressor Cells Are Associated with Viral Persistence and Downregulation of TCR ζ Chain Expression on CD8 T Cells in Chronic Hepatitis C Patients

    Qing-Lei Zeng, Bin Yang, Hong-Qi Sun, Guo-Hua Feng, Lei Jin, Zheng-Sheng Zou, Zheng Zhang, Ji-Yuan Zhang, and Fu-Sheng Wang

    Mol. Cells 2014; 37(1): 66-73 https://doi.org/10.14348/molcells.2014.2282
    Abstract

    Abstract : Myeloid-derived suppressor cells (MDSCs) play an important role in impairing the function of T cells. We characterized MDSCs in two chronic hepatitis C (CHC) cohorts: a cross-sectional group that included 61 treatment-naive patients with CHC, 14 rapid virologic response (RVR) cases and 22 early virologic response (EVR) cases; and a longitudinal group of 13 cases of RVR and 10 cases of EVR after pegylated-interferon-α/ribavirin treatment for genotype 1b HCV infection. Liver samples from 32 CHC patients and six healthy controls were subjected to immunohistochemical analysis. MDSCs frequency in treatment-naive CHC was significantly higher than in RVR, EVR, or healthy subjects and was positively correlated with HCV RNA. Patients infected with HCV genotype 2a had a significantly higher frequency of MDSCs than those infected with genotype 1b. Decreased T cell receptor (TCR) ζ expression on CD8 T cells was significantly associated with an increased frequency of MDSCs in treatment-naive CHC patients and was restored by -arginine treatment . Increased numbers of liver arginase-1 cells were closely associated with the histological activity index in CHC. The TCR ζ chain was significantly downregulated on hepatic CD8 T cells in CHC. During antiviral follow up, MDSCs frequency in peripheral blood mononuclear cells was directly correlated with the HCV RNA load in the plasma and inversely correlated with TCR ζ chain expression in CD8 T cells in both RVR and EVR cases. Notably, the RVR group had a higher frequency of MDSCs at baseline than the EVR group. Collectively, this study provides evidence that MDSCs might be associated with HCV persistence and downregulation of CD8 ζ chain expression.

Mol. Cells
May 31, 2022 Vol.45 No.5
COVER PICTURE
Fe2+ ion depletion-induced expression of BΔGFP at the early stage of leaf development (Choi et al., pp. 294-305).

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