The Experts below are selected from a list of 10530 Experts worldwide ranked by ideXlab platform
Takehisa Matsumoto - One of the best experts on this subject based on the ideXlab platform.
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Diverged nuclear localization of Werner helicase in human and mouse cells
Oncogene, 2001Co-Authors: Takahisa Suzuki, Miwa Shiratori, Yasuhiro Furuichi, Takehisa MatsumotoAbstract:Werner syndrome (WS) is a rare autosomal recessive genetic disorder causing premature aging and rare cancers. A gene responsible for WS ( WRN ) encodes a protein with 1432 amino acids (a.a.) homologous to the E. coli RecQ -type DNA helicase. Transcriptional activation facilitated nucleolar localization of human WRN protein (hWRNp) and serum starvation induced translocation of hWRNp from the nucleoli to the Nucleoplasm in human cultured cells, suggesting a nucleolar-Nucleoplasm trafficking of hWRNp depending on transcriptional state. Mutant hWRNp lacking the C-terminal 30 a.a. residues (Δ1403–1432) failed to localize in the nucleolus, whereas Δ1405–1432 can migrate into the nucleolus. Here we identify a region putative for nucleolar localization signal (NoLS) containing a sequence of two positively charged amino acids (Arg^1403-Lys^1404) in the C-terminal area of hWRNp. By contrast, the mouse homolog (mWRNp) exists only in the Nucleoplasm. We show that the inability of mWRNp to migrate into the nucleolus is due to a difference of a sequence in the region corresponding to the NoLS of hWRNp. In addition, mouse cells cannot recognize the NoLS of hWRNp. Our study suggests that defect in nucleolar function of hWRNp may be linked to the premature aging which is not observed in mWRN ^−/− mice.
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Diverged nuclear localization of Werner helicase in human and mouse cells.
Oncogene, 2001Co-Authors: Takahisa Suzuki, Miwa Shiratori, Yasuhiro Furuichi, Takehisa MatsumotoAbstract:: Werner syndrome (WS) is a rare autosomal recessive genetic disorder causing premature aging and rare cancers. A gene responsible for WS (WRN) encodes a protein with 1432 amino acids (a.a.) homologous to the E. coli RecQ-type DNA helicase. Transcriptional activation facilitated nucleolar localization of human WRN protein (hWRNp) and serum starvation induced translocation of hWRNp from the nucleoli to the Nucleoplasm in human cultured cells, suggesting a nucleolar-Nucleoplasm trafficking of hWRNp depending on transcriptional state. Mutant hWRNp lacking the C-terminal 30 a.a. residues (Delta1403-1432) failed to localize in the nucleolus, whereas Delta1405-1432 can migrate into the nucleolus. Here we identify a region putative for nucleolar localization signal (NoLS) containing a sequence of two positively charged amino acids (Arg(1403)-Lys(1404)) in the C-terminal area of hWRNp. By contrast, the mouse homolog (mWRNp) exists only in the Nucleoplasm. We show that the inability of mWRNp to migrate into the nucleolus is due to a difference of a sequence in the region corresponding to the NoLS of hWRNp. In addition, mouse cells cannot recognize the NoLS of hWRNp. Our study suggests that defect in nucleolar function of hWRNp may be linked to the premature aging which is not observed in mWRN(-/-) mice.
Gunnar Haukenes - One of the best experts on this subject based on the ideXlab platform.
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subcellular distribution of human immunodeficiency virus type 1 rev and colocalization of rev with rna splicing factors in a speckled pattern in the Nucleoplasm
Journal of Virology, 1994Co-Authors: Karlhenning Kalland, Anne Marie Szilvay, E Langhoff, Gunnar HaukenesAbstract:The human immunodeficiency virus type 1 (HIV-1) Rev (regulator of virion protein expression) protein exemplifies a new type of posttranscriptional regulation. One main function of Rev is to increase the cytoplasmic expression of unspliced and incompletely spliced retroviral mRNAs from which viral structural proteins are made. In that way, Rev is essential in order to complete the retroviral life cycle. The biology of Rev in the host cell has remained elusive. In this study, a complex distribution of Rev in single cells was found. Rev was found in the cytoplasm, in a perinuclear zone, in the Nucleoplasm, and in the nucleoli. In the Nucleoplasm, Rev colocalized in a speckled pattern with host cell factors known to assemble on nascent transcripts. Those factors are involved in the processing of heterogeneous RNA to spliced mRNA in the Nucleoplasm of all cells. The distribution of Rev was dependent only on Rev and host cell interactions, since neither the Rev target RNA nor other HIV proteins were expressed in the cells. Rev was found in the same subcellular compartments of cells treated for extended periods with cycloheximide, an inhibitor of protein synthesis. This finding implies that Rev shuttles continuously between cytoplasmic and Nucleoplasmic compartments. The results suggest a potential role for Rev both in the RNA-splicing process and in the nucleocytoplasmic transport of Rev-dependent HIV mRNA.
Thoru Pederson - One of the best experts on this subject based on the ideXlab platform.
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rapid diffusional shuttling of poly a rna between nuclear speckles and the Nucleoplasm
Molecular Biology of the Cell, 2005Co-Authors: Joan Ritland C Politz, David L Spector, Richard A Tuft, Kannanganattu V Prasanth, Nina Baudendistel, Kevin E Fogarty, Lawrence M Lifshitz, Jorg Langowski, Thoru PedersonAbstract:Speckles are nuclear bodies that contain pre-mRNA splicing factors and polyadenylated RNA. Because nuclear poly(A) RNA consists of both mRNA transcripts and nucleus-restricted RNAs, we tested whether poly(A) RNA in speckles is dynamic or rather an immobile, perhaps structural, component. Fluorescein-labeled oligo(dT) was introduced into HeLa cells stably expressing a red fluorescent protein chimera of the splicing factor SC35 and allowed to hybridize. Fluorescence correlation spectroscopy (FCS) showed that the mobility of the tagged poly(A) RNA was virtually identical in both speckles and at random Nucleoplasmic sites. This same result was observed in photoactivation-tracking studies in which caged fluorescein-labeled oligo(dT) was used as hybridization probe, and the rate of movement away from either a speckle or Nucleoplasmic site was monitored using digital imaging microscopy after photoactivation. Furthermore, the tagged poly(A) RNA was observed to rapidly distribute throughout the entire Nucleoplasm and other speckles, regardless of whether the tracking observations were initiated in a speckle or the Nucleoplasm. Finally, in both FCS and photoactivation-tracking studies, a temperature reduction from 37 to 22°C had no discernible effect on the behavior of poly(A) RNA in either speckles or the Nucleoplasm, strongly suggesting that its movement in and out of speckles does not require metabolic energy.
Edouard Bertrand - One of the best experts on this subject based on the ideXlab platform.
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Box C/D small nucleolar RNA trafficking involves small nucleolar RNP proteins, nucleolar factors and a novel nuclear domain
EMBO Journal, 2001Co-Authors: C. Verheggen, Marc Thiry, J. Mouaikel, J. M. Blanchard, D. Tollervey, R. Bordonne, D. L. Lafontaine, Edouard BertrandAbstract:Nucleolar localization of box C/D small nucleolar (sno) RNAs requires the box C/D motif and, in vertebrates, involves transit through Cajal bodies (CB). We report that in yeast, overexpression of a box C/D reporter leads to a block in the localization pathway with snoRNA accumulation in a specific sub-nucleolar structure, the nucleolar body (NB). The human survival of motor neuron protein (SMN), a marker of gems/CB, specifically localizes to the NB when expressed in yeast, supporting similarities between these structures. Box C/D snoRNA accumulation in the NB was decreased by mutation of Srp40 and increased by mutation of Nsr1p, two related nucleolar proteins that are homologous to human Nopp140 and nucleolin, respectively. Box C/D snoRNAs also failed to accumulate in the NB, and became delocalized to the Nucleoplasm, upon depletion of any of the core snoRNP proteins, Nop1p/fibrillarin, Snu13p, Nop56p and Nop5p/Nop58p. We conclude that snoRNP assembly occurs either in the Nucleoplasm, or during transit of snoRNAs through the NB, followed by routing of the complete snoRNP to functional sites of ribosome synthesis.
David L Spector - One of the best experts on this subject based on the ideXlab platform.
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rapid diffusional shuttling of poly a rna between nuclear speckles and the Nucleoplasm
Molecular Biology of the Cell, 2005Co-Authors: Joan Ritland C Politz, David L Spector, Richard A Tuft, Kannanganattu V Prasanth, Nina Baudendistel, Kevin E Fogarty, Lawrence M Lifshitz, Jorg Langowski, Thoru PedersonAbstract:Speckles are nuclear bodies that contain pre-mRNA splicing factors and polyadenylated RNA. Because nuclear poly(A) RNA consists of both mRNA transcripts and nucleus-restricted RNAs, we tested whether poly(A) RNA in speckles is dynamic or rather an immobile, perhaps structural, component. Fluorescein-labeled oligo(dT) was introduced into HeLa cells stably expressing a red fluorescent protein chimera of the splicing factor SC35 and allowed to hybridize. Fluorescence correlation spectroscopy (FCS) showed that the mobility of the tagged poly(A) RNA was virtually identical in both speckles and at random Nucleoplasmic sites. This same result was observed in photoactivation-tracking studies in which caged fluorescein-labeled oligo(dT) was used as hybridization probe, and the rate of movement away from either a speckle or Nucleoplasmic site was monitored using digital imaging microscopy after photoactivation. Furthermore, the tagged poly(A) RNA was observed to rapidly distribute throughout the entire Nucleoplasm and other speckles, regardless of whether the tracking observations were initiated in a speckle or the Nucleoplasm. Finally, in both FCS and photoactivation-tracking studies, a temperature reduction from 37 to 22°C had no discernible effect on the behavior of poly(A) RNA in either speckles or the Nucleoplasm, strongly suggesting that its movement in and out of speckles does not require metabolic energy.
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organization of the double stranded rna activated protein kinase dai and virus associated va rnai in adenovirus 2 infected hela cells
Journal of Cell Science, 1993Co-Authors: Luis Felipe Jimenezgarcia, Simon R Green, Michael B Mathews, David L SpectorAbstract:We have examined the cellular distribution of the double-stranded RNA-activated protein kinase DAI in adenovirus 2 (Ad2)-infected and uninfected HeLa cells. In uninfected cells DAI was found to be concentrated in the cytoplasm. In addition, DAI was localized in the nucleoli and diffusely distributed throughout the Nucleoplasm. Cells treated with alpha-interferon displayed a similar pattern of distribution for DAI. When RNA polymerase I activity was inhibited by the drug actinomycin D, nucleoli segregated and DAI was found to colocalize with the dense fibrillar region of the nucleoli. During mitosis, the distribution of DAI paralleled that of rRNA. In adenovirus-infected cells the localization of DAI was similar to that in uninfected interphase cells. VA RNAI was detected in Ad2-infected cells by 10-14 hours post-infection as fine dots in the Nucleoplasm. By 18-24 hours post-infection, VA RNAI appeared in bigger and more abundant dots in the Nucleoplasm and the cytoplasm was intensively labeled. Transient expression of the VA RNAI gene in uninfected cells resulted in a similar localization of the RNA. Our results are consistent with a role for DAI and VA RNAI in protein synthesis and suggest that DAI may play an early role in ribosome biogenesis in the nucleolus in addition to its cytoplasmic role in translation.
