scholarly journals Armadillo nuclear import is regulated by cytoplasmic anchor Axin and nuclear anchor dTCF/Pan

Development ◽  
2001 ◽  
Vol 128 (11) ◽  
pp. 2107-2117 ◽  
Author(s):  
Nicholas S. Tolwinski ◽  
Eric Wieschaus
Keyword(s):  
Drosophila Melanogaster ◽  
Plasma Membrane ◽  
Nuclear Import ◽  
Current Model ◽  
Cellular Distribution ◽  
Nuclear Retention ◽  
Binding Partners ◽  
Wingless Signaling ◽  
Anchoring System ◽  
Import And Export

Drosophila melanogaster Armadillo plays two distinct roles during development. It is a component of adherens junctions, and functions as a transcriptional activator in response to Wingless signaling. In the current model, Wingless signal causes stabilization of cytoplasmic Armadillo allowing it to enter the nucleus where it can activate transcription. However, the mechanism of nuclear import and export remains to be elucidated. In this study, we show that two gain-of-function alleles of Armadillo activate Wingless signaling by different mechanisms. The S10 allele was previously found to localize to the nucleus, where it activates transcription. In contrast, the ΔArm allele localizes to the plasma membrane, and forces endogenous Arm into the nucleus. Therefore, ΔArm is dependent on the presence of a functional endogenous allele of arm to activate transcription. We show that ΔArm may function by titrating Axin protein to the membrane, suggesting that it acts as a cytoplasmic anchor keeping Arm out of the nucleus. In axin mutants, Arm is localized to the nuclei. We find that nuclear retention is dependent on dTCF/Pangolin. This suggests that cellular distribution of Arm is controlled by an anchoring system, where various nuclear and cytoplasmic binding partners determine its localization.

scholarly journals A Protamine Knockdown Mimics the Function of Sd in Drosophila melanogaster

2020 ◽  
Vol 10 (6) ◽  
pp. 2111-2115 ◽  
Author(s):  
Luke F. Gingell ◽  
Janna R. McLean
Keyword(s):  
Drosophila Melanogaster ◽  
Nuclear Import ◽  
Nuclear Transport ◽  
Protein A ◽  
Natural Populations ◽  
Meiotic Drive ◽  
Gene Complex ◽  
Unique Role ◽  
Spermatid Nucleus ◽  
Import And Export

Segregation Distorter (SD) is an autosomal meiotic drive system found worldwide in natural populations of Drosophila melanogaster. This gene complex induces the preferential and nearly exclusive transmission of the SD chromosome in SD/SD+ males. This selfish propagation occurs through the interplay of the Sd locus, its enhancers and the Rsps locus during spermatid development. The key distorter locus, Sd, encodes a truncated but enzymatically active RanGAP (RanGTPase-activating protein), a key nuclear transport factor in the Ran signaling pathway. When encoded by Sd, RanGAP is mislocalized to the nucleus interior, which then traps Ran inside the nucleus and disrupts nuclear import. As a result of this aberrant nuclear transport, a process known as the histone-to-protamine transition that is required for proper spermatid condensation fails to occur in SD/SD+ males. In this process, sperm-specific protamine proteins enter the spermatid nucleus and replace the formerly chromatin-complexed histones. Previously, we have shown that mutations affecting nuclear import and export can enhance distortion in an SD background, thus verifying that a defect in nuclear transport is responsible for the unequal transmission of chromosomes. Herein, we show that specifically reducing protamines induces distortion in an SD background, verifying that protamines are transported via the RanGAP/GEF pathway and indicating that E(SD) plays a significant and unique role in the process of distortion.

scholarly journals Identification of Novel Import and Export Signals of Human TAP, the Protein That Binds to the Constitutive Transport Element of the Type D Retrovirus mRNAs

1999 ◽  
Vol 19 (9) ◽  
pp. 6306-6317 ◽  
Author(s):  
Jenifer Bear ◽  
Wei Tan ◽  
Andrei S. Zolotukhin ◽  
Carlos Tabernero ◽  
Eric A. Hudson ◽  
...  
Keyword(s):  
Nuclear Import ◽  
Nuclear Export ◽  
Nuclear Protein ◽  
Terminal Portion ◽  
Nuclear Retention ◽  
Constitutive Transport Element ◽  
Type D ◽  
Acid Protein ◽  
Import And Export ◽  
Amino Acid Protein

ABSTRACT The nuclear export of the unspliced type D retrovirus mRNA depends on the cis-acting constitutive transport RNA element (CTE) that has been shown to interact with the human TAP (hTAP) protein promoting the export of the CTE-containing mRNAs. We report here that hTAP is a 619-amino-acid protein extending the previously identified protein by another 60 residues at the N terminus and that hTAP shares high homology with the predicted rat and mouse TAP proteins. We found that hTAP is a nuclear protein that accumulates in the nuclear rim and the nucleoplasm. We further demonstrated that hTAP is able to shuttle between the nucleus and the cytoplasm. Identification of the signals responsible for nuclear import (NLS) and export (NES) revealed that they are distinct but partially overlapping. NLS and NES of hTAP are active transferable signals that do not share similarities with known elements. The C-terminal portion contributes further to hTAP’s nuclear retention and contains a signal(s) for nuclear rim association. Taken together, our data show that hTAP is a dynamic protein capable of bidirectional trafficking across the nuclear envelope. These data further support hTAP’s role as an export factor of the CTE-containing mRNAs.

scholarly journals Optineurin links myosin VI to the Golgi complex and is involved in Golgi organization and exocytosis

2005 ◽  
Vol 169 (2) ◽  
pp. 285-295 ◽  
Author(s):  
Daniela A. Sahlender ◽  
Rhys C. Roberts ◽  
Susan D. Arden ◽  
Giulietta Spudich ◽  
Marcus J. Taylor ◽  
...  
Keyword(s):  
Plasma Membrane ◽  
Rna Interference ◽  
Vesicular Stomatitis Virus ◽  
Protein Interaction ◽  
Golgi Complex ◽  
Myosin Vi ◽  
Binding Partner ◽  
Binding Partners ◽  
Vesicular Stomatitis ◽  
Golgi Organization

Myosin VI plays a role in the maintenance of Golgi morphology and in exocytosis. In a yeast 2-hybrid screen we identified optineurin as a binding partner for myosin VI at the Golgi complex and confirmed this interaction in a range of protein interaction studies. Both proteins colocalize at the Golgi complex and in vesicles at the plasma membrane. When optineurin is depleted from cells using RNA interference, myosin VI is lost from the Golgi complex, the Golgi is fragmented and exocytosis of vesicular stomatitis virus G-protein to the plasma membrane is dramatically reduced. Two further binding partners for optineurin have been identified: huntingtin and Rab8. We show that myosin VI and Rab8 colocalize around the Golgi complex and in vesicles at the plasma membrane and overexpression of constitutively active Rab8-Q67L recruits myosin VI onto Rab8-positive structures. These results show that optineurin links myosin VI to the Golgi complex and plays a central role in Golgi ribbon formation and exocytosis.

scholarly journals Nuclear Import and Export Signals Control the Subcellular Localization of Nurr1 Protein in Response to Oxidative Stress

2013 ◽  
Vol 288 (8) ◽  
pp. 5506-5517 ◽  
Author(s):  
Ángel Juan García-Yagüe ◽  
Patricia Rada ◽  
Ana I. Rojo ◽  
Isabel Lastres-Becker ◽  
Antonio Cuadrado
Keyword(s):  
Oxidative Stress ◽  
Subcellular Localization ◽  
Nuclear Import ◽  
Import And Export

scholarly journals Nuclear Import of TFIIB Is Mediated by Kap114p, a Karyopherin with Multiple Cargo-binding Domains

2005 ◽  
Vol 16 (7) ◽  
pp. 3200-3210 ◽  
Author(s):  
Jennifer L. Hodges ◽  
Jennifer H. Leslie ◽  
Nima Mosammaparast ◽  
Yurong Guo ◽  
Jeffrey Shabanowitz ◽  
...  
Keyword(s):  
Nuclear Import ◽  
Binding Sites ◽  
Binding Domains ◽  
Transcription Factor Iib ◽  
General Transcription Factor ◽  
Proteomic Approach ◽  
Evolutionarily Conserved ◽  
Import And Export ◽  
Transport Factors

Nuclear import and export is mediated by an evolutionarily conserved family of soluble transport factors, the karyopherins (referred to as importins and exportins). The yeast karyopherin Kap114p has previously been shown to import histones H2A and H2B, Nap1p, and a component of the preinitiation complex (PIC), TBP. Using a proteomic approach, we have identified several potentially new cargoes for Kap114p. These cargoes include another PIC component, the general transcription factor IIB or Sua7p, which interacted directly with Kap114p. Consistent with its role as a Sua7p import factor, deletion of KAP114 led to specific mislocalization of Sua7p to the cytoplasm. An interaction between Sua7p and TBP was also detected in cytosol, raising the possibility that both Sua7p and TBP can be coimported by Kap114p. We have also shown that Kap114p possesses multiple overlapping binding sites for its partners, Sua7p, Nap1p, and H2A and H2B, as well as RanGTP and nucleoporins. In addition, we have assembled an in vitro complex containing Sua7p, Nap1p, and histones H2A and H2B, suggesting that this Kap may import several proteins simultaneously. The import of more than one cargo at a time would increase the efficiency of each import cycle and may allow the regulation of coimported cargoes.

scholarly journals The canonical Wingless signaling pathway is required but not sufficient for inflow tract formation in the Drosophila melanogaster heart

2016 ◽  
Vol 413 (1) ◽  
pp. 16-25 ◽  
Author(s):  
Gloriana V. Trujillo ◽  
Dalea H. Nodal ◽  
Candice V. Lovato ◽  
Jill D. Hendren ◽  
Lynda A. Helander ◽  
...  
Keyword(s):  
Drosophila Melanogaster ◽  
Signaling Pathway ◽  
Wingless Signaling

scholarly journals FRAP analysis of nucleocytoplasmic dynamics of the vitamin D receptor splice variant VDRB1: preferential targeting to nuclear speckles

2005 ◽  
Vol 388 (2) ◽  
pp. 509-514 ◽  
Author(s):  
Kathryn L. SUNN ◽  
John A. EISMAN ◽  
Edith M. GARDINER ◽  
David A. JANS
Keyword(s):  
Vitamin D ◽  
Vitamin D Receptor ◽  
Nuclear Import ◽  
Protein Import ◽  
Nucleocytoplasmic Transport ◽  
Nuclear Speckles ◽  
Nuclear Targeting ◽  
Nuclear Retention ◽  
First Time

Although the key components of the cellular nuclear transport machinery have largely been characterized through extensive efforts in recent years, in vivo measurements of the kinetics of nuclear protein import/export are patently few. The present study applies the approach of FRAP (fluorescence recovery after photobleaching) to examine the nucleocytoplasmic flux of a novel human VDRB1 (vitamin D receptor B1) isoform in living cells. Through an N-terminal extension containing a consensus nuclear targeting sequence, VDRB1 is capable of localizing in nuclear speckles adjacent to SC-35 (35 kDa splicing component)-containing speckles as well as in the nucleoplasm, dependent on ligand. Investigation of VDRB1 nucleocytoplasmic transport using FRAP indicates for the first time that the VDRB1 has a serum-modulated, active nuclear import mechanism. There is no evidence of an efficient, active export mechanism for VDRB1, probably as a result of nuclear retention. VDRB1 nuclear import in the absence of serum occurred more rapidly and to a greater extent to nuclear speckles compared with import to other nuclear sites. This preferential transport from the cytoplasm to and accumulation within nuclear speckles is consistent with the idea that the latter represent dynamic centres of VDRB1 interaction with other nuclear proteins. The results are consistent with the existence of specialized pathways to target proteins to nuclear subdomains.

scholarly journals Transport of vesicular stomatitis virus G protein to the cell surface is signal mediated in polarized and nonpolarized cells.

1996 ◽  
Vol 133 (3) ◽  
pp. 543-558 ◽  
Author(s):  
A Müsch ◽  
H Xu ◽  
D Shields ◽  
E Rodriguez-Boulan
Keyword(s):  
Plasma Membrane ◽  
Membrane Proteins ◽  
G Protein ◽  
Vesicular Stomatitis Virus ◽  
Mdck Cells ◽  
Current Model ◽  
Gh3 Cells ◽  
Plasma Membrane Proteins ◽  
Vesicular Release ◽  
Vesicular Stomatitis

Current model propose that in nonpolarized cells, transport of plasma membrane proteins to the surface occurs by default. In contrast, compelling evidence indicates that in polarized epithelial cells, plasma membrane proteins are sorted in the TGN into at least two vectorial routes to apical and basolateral surface domains. Since both apical and basolateral proteins are also normally expressed by both polarized and nonpolarized cells, we explored here whether recently described basolateral sorting signals in the cytoplasmic domain of basolateral proteins are recognized and used for post TGN transport by nonpolarized cells. To this end, we compared the inhibitory effect of basolateral signal peptides on the cytosol-stimulated release of two basolateral and one apical marker in semi-intact fibroblasts (3T3), pituitary (GH3), and epithelial (MDCK) cells. A basolateral signal peptide (VSVGp) corresponding to the 29-amino acid cytoplasmic tail of vesicular stomatitis virus G protein (VSVG) inhibited with identical potency the vesicular release of VSVG from the TGN of all three cell lines. On the other hand, the VSVG peptide did not inhibit the vesicular release of HA in MDCK cells not of two polypeptide hormones (growth hormone and prolactin) in GH3 cells, whereas in 3T3 cells (influenza) hemagglutinin was inhibited, albeit with a 3x lower potency than VSVG. The results support the existence of a basolateral-like, signal-mediated constitutive pathway from TGN to plasma membrane in all three cell types, and suggest that an apical-like pathway may be present in fibroblast. The data support cargo protein involvement, not bulk flow, in the formation of post-TGN vesicles and predict the involvement of distinct cytosolic factors in the assembly of apical and basolateral transport vesicles.

Sign in / Sign up

Export Citation Format

Share Document