Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “nuclear localization”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 271 records · Page 15Linked to original sources
PubMed2000

Genetic alterations disrupting the nuclear localization of the retinoblastoma-related gene RB2/p130 in human tumor cell lines and primary tumors.

The prototypic tumor suppressor gene, the retinoblastoma gene (RB/ p105), is mutated in a variety of human tumors. However, to date, mutational data on retinoblastoma family members p107 and RB2/p130 in tumors is lacking. We studied the expression of pRb2/p130 by immunocytochemistry and Western blot analysis in a panel of human osteosarcoma and lymphoid cell lines. Only the lymphoid cell lines showed an abnormal cytoplasmic localization of pRb2/p130, suggesting possible alterations within the region of nuclear localization signaling. We screened these cell lines for genetic alterations of the RB2/p130 gene in the region of the putative bipartite nuclear localization signal (NLS). This region is highly homologous with that of the RB/p105 gene. In addition, we screened four primary Burkitt's lymphomas for genetic alterations in the RB2/p130 gene. Naturally occurring mutations, which disrupt the putative bipartite NLS, were found in lymphoma cell lines and primary tumors, but not in the osteosarcoma cell lines, where normal nuclear localization of the protein was detectable. Site-directed mutagenesis and transfection assay using NLS mutants displayed markedly reduced biological activity as measured by flow cytometric analysis. This study clearly describes RB2/ p130 as an important target for mutations and subsequent inactivation in lymphoma pathogenesis, thus validating that RB2/p130 is a classical tumor suppressor gene.

Amino Acid Substitution↗
PubMed1990

Homeodomain of yeast repressor alpha 2 contains a nuclear localization signal.

The yeast repressor alpha 2 is shown, by analysis of deletion-bearing alpha 2-beta-galactosidase hybrid proteins, to have two structurally distinct nuclear localization signals. The cellular location of hybrid proteins was determined by indirect immunofluorescence and optical sectioning of whole fixed yeast cells. The two nuclear localization signals are far apart in the alpha 2 primary structure and do not have any sequence homology. One signal is, as reported previously, within the aminoterminal 13 amino acids of alpha 2. Deletion of only this aminoterminal signal has no evident effect on nuclear localization. The second signal is in a central portion of alpha 2, within the alpha 2 homeodomain. Since this signal is within the amino terminus of the alpha 2 homeodomain, the homeodomain mediates nuclear localization in addition to, and independently of, DNA binding. Deletion of only this second signal results in inefficient localization and accumulation of mutant protein at discrete sites on the nuclear envelope assumed to be nuclear pores. We propose that the two signals in alpha 2 are functionally distinct and act at different steps in a localization pathway.

Base Sequence↗
PubMed2004

Characterization of nuclear localization and export signals of the major tegument protein VP8 of bovine herpesvirus-1.

Bovine herpesvirus-1 (BHV-1) VP8 is found in the nucleus immediately after infection. Transient expression of VP8 fused to yellow fluorescent protein (YFP) in COS-7 cells confirmed the nuclear localization of VP8 in the absence of other viral proteins. VP8 has four putative nuclear localization signals (NLS). Deletion of pat4 ((51)RRPR(54)) or pat7 ((48)PRVRRPR(54)) NLS2 abrogated nuclear accumulation, whereas deletion of (48)PRV(50) did not, so pat4 NLS2 is critical for nuclear localization of VP8. Furthermore, NLS1 ((11)RRPRR(15)), pat4 NLS2, and pat7 NLS2 were all capable of transporting the majority of YFP to the nucleus. Finally, a 12-amino-acid peptide with the sequence RRPRRPRVRRPR directed all of YFP into the nucleus, suggesting that reiteration of the RRPR motif makes the nuclear localization more efficient. Heterokaryon assays demonstrated that VP8 is also capable of shuttling between the nucleus and cytoplasm of the cell. Deletion mutant analysis revealed that this property is attributed to a leucine-rich nuclear export sequence (NES) consisting of amino acids (485)LSAYLTLFVAL(495). This leucine-rich NES caused transport of YFP to the cytoplasm. These results demonstrate that VP8 shuttles between the nucleus and cytoplasm.

Active Transport, Cell Nucleus↗
PubMedDate not supplied

Targeted delivery of plasmid DNA into the nucleus of cells via nuclear localization signal peptide conjugated to DNA intercalating bis- and trisacridines.

Efficient nuclear targeting via nonviral delivery of DNA is still an unmet challenge in gene therapy. We have synthesized a novel 9-aminoacridine amino acid monomer that conveniently allows multiple acridines to be incorporated into peptide conjugates. In particular we have prepared bis- and trisacridine conjugates of nuclear localization signal peptide (NLS) ((Acr)2-NLS and (Acr)3-NLS) and studied these as functional transporters for the nuclear delivery of DNA. We show that these conjugates can enhance transfection efficacy as well as nuclear localization of plasmid DNA by more than 50-fold when combined with polyethylenimine at an N:P ratio of 2-3. These conjugates have high reversible affinity for double stranded DNA by intercalation and the technique provides a simple means of associating NLS with DNA of any sequence and at any ratio.

Acridines↗
PubMed1995

Phosphorylation and nuclear localization of the hepatitis B virus core protein: significance of serine in the three repeated SPRRR motifs.

Hepatitis B virus core protein (antigen) is an important serologic marker of hepatitis B virus infection. This protein is found in the cytoplasm or the nuclei, or both, of infected hepatocytes. A nuclear localization signal has previously been identified in the core protein sequence. This signal overlaps three repeated SPRRR motifs. In this report, we demonstrate that substitution of all of the serine residues in these three SPRRR motifs with alanine can prevent almost entirely the phosphorylation of the core protein in Huh-7 hepatoma cells, enhance nuclear localization of the core protein in both Huh-7 and nonhepatic cells, and abolish cell cycle regulation of nuclear localization of the core protein. Since the three core protein mutants which retained only one serine residue of each of the three SPRRR motifs could be phosphorylated to similar degrees, these three serine residues likely could serve as the acceptor sites for phosphorylation with equal efficiency. These results, together with the observation that the three SPRRR motifs overlap the nuclear localization signal of the core protein, raise the possibility that nuclear localization of the core protein is negatively regulated by phosphorylation of the serine residues in the SPRRR motifs.

3T3 Cells↗
PubMed1987

Amino acid sequences that determine the nuclear localization of yeast histone 2B.

Histone-beta-galactosidase protein fusions were used to identify the domain of yeast histone 2B, which targets this protein to the nucleus. Amino acids 28 to 33 in H2B were required for nuclear localization of such fusion proteins and thus constitute a nuclear localization sequence. The amino acid sequence in this region (Gly-29 Lys Lys Arg Ser Lys Ala) is similar to the nuclear location signal in simian virus 40 large T antigen (Pro-126 Lys Lys Lys Arg Lys Val) (D. Kalderon, B.L. Roberts, W.D. Richardson, and A.E. Smith, Cell 39:499-509, 1984). A point mutation changing lysine 31 to methionine abolished nuclear localization of an H2B-beta-galactosidase fusion protein containing amino acids 1 to 33 of H2B. However, an H2B-beta-galactosidase fusion protein containing both this point mutation and the H2A interaction domain of H2B was nuclear localized. These results suggest that H2A and H2B may be cotransported to the nucleus as a heterodimer.

Amino Acid Sequence↗
PubMed2006

Identification of multiple nuclear localization signals in murine Elf3, an ETS transcription factor.

We investigated nuclear localization signal (NLS) determinants within the AT-hook and ETS DNA-binding domains of murine Elf3 (mElf3), a member of the subfamily of epithelium-specific ETS transcription factors. Deletion mutants containing the AT-hook, ETS domain or both localized strictly in the nucleus, suggesting that these individual domains contain independent NLS motif(s). Within the AT-hook domain, four basic residues (244KRKR247) were critical for strong NLS activity, and two potent bipartite NLS motifs (236-252 and 249-267) were sufficient for nuclear import of mElf3, although less efficient than the full domain. In addition, one stretch of basic residues (318KKK320) within the ETS domain appears to be essential for mElf3 nuclear localization. Taken together, mElf3 contains multiple NLS motifs, which may function cooperatively to effect efficient nuclear transport.

Active Transport, Cell Nucleus↗
PubMed1998

Search for a nuclear localization signal in the prion protein.

Spongiform transmissible encephalopathies are neurodegenerative diseases characterized by the accumulation, in infected brains, of a pathological form of a normal host-encoded protein called PrP. Previous data have shown that PrP could interact with cytosolic factors, including nuclear molecules, emphasizing the possible function of such interactions. Moreover, in infected cells, PrP is observed not only at the plasma membrane but also in the nuclear compartment. The N-terminal extremity of the mature PrP has been thought to harbor a nuclear localization signal reminiscent of the nuclear localization signal of the simian virus 40 large T antigen. By designing a fusion protein between the putative nuclear localization signal of PrP and the green fluorescent protein, we have shown that the N-terminal sequence of PrP is not efficient in targeting the protein in the nuclear compartment. This implies new insights regarding the way by which PrP could, however, reach the nuclear compartment.

Amino Acid Sequence↗
PubMed2004

The nuclear localization signal and the C-terminal region of FHY1 are required for transmission of phytochrome A signals.

Plants use the family of phytochrome photoreceptors to sense their light environment in the red/far-red region of the spectrum. Phytochrome A (phyA) is the primary photoreceptor that regulates germination and early seedling development. This phytochrome mediates seedling de-etiolation for the developmental transition from heterotrophic to photoauxotrophic growth. High intensity far-red light provides a way to specifically assess the role of phyA in this process and was used to isolate phyA-signaling intermediates. fhy1 and pat3 (renamed fhy1-3) are independently isolated alleles of a gene encoding a phyA signal transduction component. FHY1 is a small 24 kDa protein that shows no homology to known functional motifs, besides a small conserved septin-related domain at the C-terminus, a putative nuclear localization signal (NLS) and a putative nuclear exclusion signal (NES). Here we demonstrate that the septin-related domain is important for FHY1 to transmit phyA signals. Moreover, the putative NLS and NES of FHY1 are indeed involved in its nuclear localization and exclusion. Nuclear localization of FHY1 is needed for it to execute responses downstream of phyA. Together with the results from global expression analysis, our findings point to an important role of FHY1 in phyA signaling through its nuclear translocation and induction of gene expression.

Amino Acid Sequence↗
PubMed2002

A short peptide at the C terminus is responsible for the nuclear localization of RAG2.

The RAG1 and RAG2 proteins are the lymphoid-specific factors essential for V(D)J recombination, the process that leads to the diversification of antigen receptors on B and T lymphocytes. Nucleolar/nuclear localization of RAG1 is mediated by four basic domains, which are the binding sites for the nuclear transport proteins SRP1 and RCH1, and by a nuclear localization signal (NLS) in the fifth basic domain. The C-terminal region of RAG2 from amino acids (aa) 417 to 484 shows a homology with the PHD domain of other proteins involved in chromatin-mediated gene regulation by protein-protein interactions. Mutations in this domain were shown to be responsible for several diseases and in some case lead to altered subcellular localization of proteins. We found that the C-terminal PHD domain of RAG2 is not responsible for the nuclear localization of the protein. We report here the characterization of a region (aa 491-527) in the C-terminal domain of RAG2, downstream of the putative PHD domain, which directs the nuclear localization of the protein.

Adaptor Proteins, Signal Transducing↗
PubMed2005

Identification of novel nuclear localization signal within the ErbB-2 protein.

ErbB2, a member of the receptor tyrosine kinase family, is frequently over-expressed in breast cancer. Proteolysis of the extracellular domain of ErbB2 results in constitutive activation of ErbB2 kinase. Recent study reported that ErbB2 is found in the nucleus. Here, we showed that ErbB2 is imported into the nucleus through a nuclear localization signal (NLS)-mediated mechanism. The NLS sequence KRRQQKIRKYTMRR (aa655-668) contains three clusters of basic amino acids and it is sufficient to target GFP into the nucleus. However, mutation in any basic amino acid cluster of this NLS sequence significantly affects its nuclear localization. Furthermore, it was found that this NLS is essential for the nuclear localization of ErbB2 since the intracellular domain of Erb2 lacking NLS completely abrogates its nuclear translocation. Taken together, our study identified a novel nuclear localization signal and reveals a novel mechanism underlying ErbB2 nuclear trafficking and localization.

Amino Acids↗
PubMed2005

Maspin nuclear localization is linked to favorable morphological features in pulmonary adenocarcinoma.

Maspin, a mammary homologue of Serine Protease Inhibitors, has been shown to inhibit tumor progression and metastasis. Recently, its biological functions have been linked to its subcellular localization. Specifically, a nuclear, opposed to a combined nuclear and cytoplasmic localization has been associated with increased survival in human malignancies, including non-small cell lung cancer (NSCLC). However, it is not known whether transformation affects maspin expression during lung carcinogenesis, and whether its subcellular localization correlates with the morphological features of NSCLC. To address these questions, we studied maspin expression in a model of transformation of bronchial epithelial cells and in resected NSCLC. We found that decreased maspin accompanied chemical transformation of normal immortalized bronchial epithelial cells BEAS 2B. Immunohistochemistry revealed maspin expression to be virtually universal in NSCLC, occurring in 72/77 Adenocarcinoma (ACa), and 46/46 squamous cell carcinoma (SqCCa). SqCCa showed almost exclusively a combined nuclear-cytosolic stain. In contrast, nuclear maspin, but not combined nuclear-cytoplasmic maspin significantly correlated with low histological grade, lower proliferative rate, absence of invasion, and negative p53 stain in ACa. These data support the hypothesis that nuclear localization of maspin may stratify subtypes of NSCLC with favorable clinical-pathological features.

Adenocarcinoma↗
PubMed2003

Nuclear localization of mouse fibroblast growth factor 2 requires N-terminal and C-terminal sequences.

In vertebrates, different isoforms of fibroblast growth factor 2 (FGF2) exist, which differ by their N-terminal extension. They show different localization and expression levels and exert distinct biological effects. Nevertheless, genetic inactivation of all FGF2 isoforms in the mouse results in only mild phenotypes. Here, we analyzed mouse FGF2, and show that, as in the human, mouse FGF2 contains CTG-initiated high molecular-weight (HMW) isoforms, which contain a nuclear localization signal, and which mediate localization of this isoform to the nucleus. Using green fluorescent protein-FGF2 fusions, we furthermore observed, that C-terminal deletions disable nuclear localization of the short low-molecular-weight (LMW) 18-kDa isoform. This loss of specific localization is accompanied by a loss in heparin binding. We therefore suggest that, first, localization of mouse FGF2 is comparable to that in other vertebrates and, second, FGF2 contains at least two sequences important for nuclear localization, a nuclear localization sequence at the N terminus which is only contained in the HMW isoform, and another sequence at the C terminus, which is only required for localization of the LMW 18-kDa isoform.

Amino Acid Sequence↗
PubMed1998

Identification of a novel MCM3-associated protein that facilitates MCM3 nuclear localization.

MCM3 is essential for the initiation of DNA replication and also participates in controls that ensure DNA replication is initiated once per cell cycle. In a two-hybrid screen for proteins that interact with human MCM3, we identified and cloned a novel protein of which the calculated molecular weight is 80,291. A specific antibody against the protein identified a 80-kDa protein in HeLa cell extract, indicating the protein actually expressed in cells. The interaction of these proteins was confirmed by immunoprecipitation assay. Moreover, we clarified a nuclear localization signal of human MCM3, and we find that mutagenesis on the nuclear localization signal of MCM3 affected the binding of newly isolated MCM3-assosiated protein, Map80. Map80 was expressed in Escherichia coli as a fusion with His6 tag and purified with sequential column chromatographies. The addition of recombinant Map80 stimulated the amount of nuclear localized MCM3. These results suggest that Map80 is involved in the nuclear localization pathway of MCM3.

Acetyltransferases↗
PubMed2003

Functional and structural analyses of cryptochrome. Vertebrate CRY regions responsible for interaction with the CLOCK:BMAL1 heterodimer and its nuclear localization.

Mouse mCRY1 and zebrafish zCRY1a and zCRY3 belong to the DNA photolyase/Cryptochrome family. mCRY1 and zCRY1a repress CLOCK:BMAL1-mediated transcription, whereas zCRY3 does not. Reciprocal chimeras between zCRY1a and zCRY3 were generated to determine the zCRY1a regions responsible for nuclear translocation, interaction with the CLOCK:BMAL1 heterodimer, and repression of CLOCK:BMAL1-mediated transcription. Three regions, RD-2a-(126-196), RD-1-(197-263), and RD-2b-(264-293), were identified. Proteins in this family consist of an N-terminal alpha/beta domain and a C-terminal helical domain connected by an interdomain loop. RD-2a is within this loop, RD-1 is at the N-terminal 50 amino acids, and RD-2b at the following 31 amino acid residues of the helical domain. Either RD-2a or RD-1 is required for interaction with the CLOCK: BMAL1 heterodimer, and either RD-1 or RD-2b is required for the nuclear translocation of CRY. Both of these functions are prerequisites for the transcriptional repressor activity. The functional nuclear localizing signal in the RD-2b region also was identified. The sequence is well conserved among repressor-type CRYs, including mCRY1. Mutations in the nuclear localizing signal of mCRY1 reduce the extent of its nuclear localization. These findings show that both nuclear localization and interaction with the CLOCK:BMAL heterodimer are essential for transcriptional repression by CRY.

Amino Acid Sequence↗
PubMed1997

Glypican and biglycan in the nuclei of neurons and glioma cells: presence of functional nuclear localization signals and dynamic changes in glypican during the cell cycle.

We have investigated the expression patterns and subcellular localization in nervous tissue of glypican, a major glycosylphosphatidylinositol-anchored heparan sulfate proteoglycan that is predominantly synthesized by neurons, and of biglycan, a small, leucine-rich chondroitin sulfate proteoglycan. By laser scanning confocal microscopy of rat central nervous tissue and C6 glioma cells, we found that a significant portion of the glypican and biglycan immunoreactivity colocalized with nuclear staining by propidium iodide and was also seen in isolated nuclei. In certain regions, staining was selective, insofar as glypican and biglycan immunoreactivity in the nucleus was seen predominantly in a subpopulation of large spinal cord neurons. The amino acid sequences of both proteoglycans contain potential nuclear localization signals, and these were demonstrated to be functional based on their ability to target beta-galactosidase fusion proteins to the nuclei of transfected 293 cells. Nuclear localization of glypican beta-galactosidase or Fc fusion proteins in transfected 293 cells and C6 glioma cells was greatly reduced or abolished after mutation of the basic amino acids or deletion of the sequence containing the nuclear localization signal, and no nuclear staining was seen in the case of heparan sulfate and chondroitin sulfate proteoglycans that do not possess a nuclear localization signal, such as syndecan-3 or decorin (which is closely related in structure to biglycan). Transfection of COS-1 cells with an epitope-tagged glypican cDNA demonstrated transport of the full-length proteoglycan to the nucleus, and there are also dynamic changes in the pattern of glypican immunoreactivity in the nucleus of C6 cells both during cell division and correlated with different phases of the cell cycle. Our data therefore suggest that in certain cells and central nervous system regions, glypican and biglycan may be involved in the regulation of cell division and survival by directly participating in nuclear processes.

Animals↗
PubMed2002

E4orf6 variants with separate abilities to augment adenovirus replication and direct nuclear localization of the E1B 55-kilodalton protein.

The E4orf6 protein of group C adenovirus is an oncoprotein that, in association with the E1B 55-kDa protein and by E1B-independent means, promotes virus replication. An arginine-faced amphipathic alpha-helix in the E4orf6 protein is required for the E4orf6 protein to direct nuclear localization of the E1B 55-kDa protein and to enhance replication of an E4 deletion virus. In this study, E4orf6 protein variants containing arginine substitutions in the amphipathic alpha-helix were analyzed. Two of the six arginine residues within the alpha-helix, arginine-241 and arginine-243, were critical for directing nuclear localization of the E1B 55-kDa protein. The four remaining arginine residues appear to provide a net positive charge for the E4orf6 protein to direct nuclear localization of the E1B 55-kDa protein. The molecular determinants of the arginine-faced amphipathic alpha-helix that were required for the functional interaction between the E4orf6 and E1B 55-kDa proteins seen in the transfected cell differed from those required to support a productive infection. Several E4orf6 protein variants with arginine-to-glutamic acid substitutions that failed to direct nuclear localization of the E1B 55-kDa protein restored replication of an E4 deletion virus. Additionally, a variant containing an arginine-to-alanine substitution at position 243 that directed nuclear localization of the E1B 55-kDa protein failed to enhance virus replication. These results indicate that the ability of the E4orf6 protein to relocalize the E1B 55-kDa protein to the nucleus can be separated from the ability of the E4orf6 protein to support a productive infection.

Adenovirus E1B Proteins↗
PubMed2002

Nuclear localization of human immunodeficiency virus type 1 preintegration complexes (PICs): V165A and R166A are pleiotropic integrase mutants primarily defective for integration, not PIC nuclear import.

Retroviral replication requires the integration of reverse-transcribed viral cDNA into a cell chromosome. A key barrier to forming the integrated provirus is the nuclear envelope, and numerous regions in human immunodeficiency virus type 1 (HIV-1) have been shown to aid the nuclear localization of viral preintegration complexes (PICs) in infected cells. One region in integrase (IN), composed of Val-165 and Arg-166, was reportedly essential for HIV-1 replication and nuclear localization in all cell types. In this study we confirmed that HIV-1(V165A) and HIV-1(R166A) were replication defective and that less mutant viral cDNA localized to infected cell nuclei. However, we present three lines of evidence that argue against a specific role for Val-165 and Arg-166 in PIC nuclear import. First, results of transient transfections revealed that V165A FLAG-tagged IN and green fluorescent protein-IN fusions carrying either V165A or R166A predominantly localized to cell nuclei. Second, two different strains of previously described class II IN mutant viruses displayed similar nuclear entry profiles to those observed for HIV-1(V165A) and HIV-1(R166A), suggesting that defective nuclear import may be a common phenotype of replication-defective IN mutant viruses. Third, V165A and R166A mutants were defective for in vitro integration activity, when assayed both as PICs isolated from infected T-cells and as recombinant IN proteins purified from Escherichia coli. Based on these results, we conclude that HIV-1(V165A) and HIV-1(R166A) are pleiotropic mutants primarily defective for IN catalysis and that Val-165 and Arg-166 do not play a specific role in the nuclear localization of HIV-1 PICs in infected cells.

Active Transport, Cell Nucleus↗