scholarly journals Functional requirement of the Arabidopsis importin‐α nuclear transport receptor family in autoimmunity mediated by the NLR protein SNC1

2020 ◽  
Author(s):  
Daniel Lüdke ◽  
Charlotte Roth ◽  
Sieglinde A. Kamrad ◽  
Jana Messerschmidt ◽  
Denise Hartken ◽  
...  
Keyword(s):  
Nuclear Transport ◽  
Functional Requirement ◽  
Importin Α ◽  
Transport Receptor ◽  
Receptor Family

scholarly journals Functional requirement of the Arabidopsis importin-α nuclear transport receptor family in autoimmunity mediated by the NLR protein SNC1

2020 ◽  
Author(s):  
Daniel Lüdke ◽  
Charlotte Roth ◽  
Sieglinde A. Kamrad ◽  
Jana Messerschmidt ◽  
Denise Hartken ◽  
...  
Keyword(s):  
Pseudomonas Syringae ◽  
Nuclear Import ◽  
Nuclear Transport ◽  
Basal Resistance ◽  
Protein Protein Interaction ◽  
Cargo Proteins ◽  
Importin Α ◽  
Localization Signal ◽  
Receptor Mutant ◽  
Transport Receptor

SUMMARYIMPORTIN-α3/MOS6 (MODIFIER OF SNC1, 6) is one of nine importin-α isoforms in Arabidopsis that recruit nuclear localization signal (NLS)-containing cargo proteins to the nuclear import machinery. IMP-α3/MOS6 is required genetically for full autoimmunity of the nucleotide-binding leucine-rich repeat (NLR) immune receptor mutant snc1 (suppressor of npr1-1, constitutive 1) and MOS6 also contributes to basal disease resistance. Here, we investigated the contribution of the other importin-α genes to both types of immune responses, and we analyzed potential interactions of all importin-α isoforms with SNC1. By using reverse-genetic analyses in Arabidopsis and protein-protein interaction assays in N. benthamiana we provide evidence that among the nine α-importins in Arabidopsis, IMP-α3/MOS6 is the main nuclear transport receptor of SNC1, and that IMP-α3/MOS6 is required selectively for autoimmunity of snc1 and basal resistance to mildly virulent Pseudomonas syringae in Arabidopsis.SIGNIFICANCE STATEMENTSpecific requirement for the Arabidopsis α-importin MOS6 in snc1-mediated autoimmunity is explained by selective formation of MOS6-SNC1 nuclear import complexes.

Importin α: a multipurpose nuclear-transport receptor

2004 ◽  
Vol 14 (9) ◽  
pp. 505-514 ◽  
Author(s):  
David S. Goldfarb ◽  
Anita H. Corbett ◽  
D. Adam Mason ◽  
Michelle T. Harreman ◽  
Stephen A. Adam
Keyword(s):  
Nuclear Transport ◽  
Importin Α ◽  
Transport Receptor

Unique nuclear localization of Nile tilapia ( Oreochromis niloticus ) Neu4 sialidase is regulated by nuclear transport receptor importin α/β

Biochimie ◽  
2018 ◽  
Vol 149 ◽  
pp. 92-104 ◽  
Author(s):  
Akinobu Honda ◽  
Petros Kingstone Chigwechokha ◽  
Yuko Kamada-Futagami ◽  
Masaharu Komatsu ◽  
Kazuhiro Shiozaki
Keyword(s):  
Nuclear Localization ◽  
Oreochromis Niloticus ◽  
Nile Tilapia ◽  
Nuclear Transport ◽  
Nile Tilapia Oreochromis Niloticus ◽  
Importin Α ◽  
Transport Receptor ◽  
Neu4 Sialidase

Recognition of Nucleoplasmin by Its Nuclear Transport Receptor Importin α/β: Insights into a Complete Import Complex

Biochemistry ◽  
2010 ◽  
Vol 49 (45) ◽  
pp. 9756-9769 ◽  
Author(s):  
Jorge Falces ◽  
Igor Arregi ◽  
Petr V. Konarev ◽  
María A. Urbaneja ◽  
Dmitri I. Svergun ◽  
...  
Keyword(s):  
Nuclear Transport ◽  
Importin Α ◽  
Transport Receptor

scholarly journals mDia2 Shuttles between the Nucleus and the Cytoplasm through the Importin-α/β- and CRM1-mediated Nuclear Transport Mechanism

2008 ◽  
Vol 284 (9) ◽  
pp. 5753-5762 ◽  
Author(s):  
Takashi Miki ◽  
Katsuya Okawa ◽  
Toshihiro Sekimoto ◽  
Yoshihiro Yoneda ◽  
Sadanori Watanabe ◽  
...  
Keyword(s):  
Transport Mechanism ◽  
Nuclear Transport ◽  
Importin Α

scholarly journals Structural Basis of Importin-α-Mediated Nuclear Transport for Ku70 and Ku80

2011 ◽  
Vol 412 (2) ◽  
pp. 226-234 ◽  
Author(s):  
Agnes A.S. Takeda ◽  
Andrea C. de Barros ◽  
Chiung-Wen Chang ◽  
Boštjan Kobe ◽  
Marcos R.M. Fontes
Keyword(s):  
Nuclear Transport ◽  
Structural Basis ◽  
Importin Α

scholarly journals Export of Importin α from the Nucleus Is Mediated by a Specific Nuclear Transport Factor

Cell ◽  
1997 ◽  
Vol 90 (6) ◽  
pp. 1061-1071 ◽  
Author(s):  
Ulrike Kutay ◽  
F.Ralf Bischoff ◽  
Susanne Kostka ◽  
Regine Kraft ◽  
Dirk Görlich
Keyword(s):  
Nuclear Transport ◽  
Transport Factor ◽  
Importin Α

scholarly journals Characterization of the Human Herpesvirus 6 U69 Gene Product and Identification of Its Nuclear Localization Signal

2007 ◽  
Vol 82 (2) ◽  
pp. 710-718 ◽  
Author(s):  
Yuji Isegawa ◽  
Yoichi Miyamoto ◽  
Yoshinari Yasuda ◽  
Katsunori Semi ◽  
Kenji Tsujimura ◽  
...  
Keyword(s):  
Fusion Protein ◽  
Nuclear Localization ◽  
Nuclear Transport ◽  
Human Herpesvirus ◽  
Small Gtpase ◽  
Terminal Region ◽  
Mutant Form ◽  
Human Herpesvirus 6 ◽  
Importin Α ◽  
Herpesvirus 6

ABSTRACT To elucidate the function of the U69 protein kinase of human herpesvirus 6 (HHV-6) in vivo, we first analyzed its subcellular localization in HHV-6-infected Molt 3 cells by using polyclonal antibodies against the U69 protein. Immunofluorescence studies showed that the U69 signal localized to the nucleus in a mesh-like pattern in both HHV-6-infected and HHV6-transfected cells. A computer program predicted two overlapping classic nuclear localization signals (NLSs) in the N-terminal region of the protein; this NLS motif is highly conserved in the N-terminal region of most of the herpesvirus protein kinases examined to date. An N-terminal deletion mutant form of the protein failed to enter the nucleus, whereas a fusion protein of green fluorescent protein (GFP) and/or glutathione S-transferase (GST) and the U69 N-terminal region was transported into the nucleus, demonstrating that the predicted N-terminal NLSs of the protein actually function as NLSs. The nuclear transport of the GST-GFP fusion protein containing the N-terminal NLS of U69 was inhibited by wheat germ agglutinin and by the Q69L Ran-GTP mutant, indicating that the U69 protein is transported into the nucleus from the cytoplasm via classic nuclear transport machinery. A cell-free import assay showed that the nuclear transport of the U69 protein was mediated by importin α/β in conjunction with the small GTPase Ran. When the import assay was performed with a low concentration of each importin-α subtype, NPI2/importin-α7 elicited more efficient transport activity than did Rch1/importin-α1 or Qip1/importin-α3. These results suggest a relationship between the localization of NPI2/importin-α7 and the cell tropism of HHV-6.

scholarly journals GTP-dependent Binding and Nuclear Transport of RNA Polymerase II by Npa3 Protein

2011 ◽  
Vol 286 (41) ◽  
pp. 35553-35561 ◽  
Author(s):  
Lidija Staresincic ◽  
Jane Walker ◽  
A. Barbara Dirac-Svejstrup ◽  
Richard Mitter ◽  
Jesper Q. Svejstrup
Keyword(s):  
Rna Polymerase ◽  
Rna Polymerase Ii ◽  
Nuclear Import ◽  
Chromatin Immunoprecipitation ◽  
Nuclear Transport ◽  
Proteomic Screen ◽  
Genome Wide ◽  
Importin Α

We identified XAB1 in a proteomic screen for factors that interact with human RNA polymerase II (RNAPII). Because XAB1 has a conserved Saccharomyces cerevisiae homologue called Npa3, yeast genetics and biochemical analysis were used to dissect the significance of the interaction. Degron-dependent Npa3 depletion resulted in genome-wide transcription decreases, correlating with a loss of RNAPII from genes as measured by chromatin immunoprecipitation. Surprisingly, however, transcription in vitro was unaffected by Npa3, suggesting that it affects a process that is not required for transcription in yeast extracts. Indeed, Npa3 depletion in vivo affects nuclear localization of RNAPII; the polymerase accumulates in the cytoplasm. Npa3 is a member of the GPN-LOOP family of GTPases. Npa3 mutants that either cannot bind GTP or that bind but cannot hydrolyze it are inviable and unable to support nuclear transport of RNAPII. Surprisingly, we were unable to detect interactions between Npa3 and proteins in the classical importin α/β pathway for nuclear import. Interestingly, Npa3-RNAPII binding is significantly increased by the addition of GTP or its slowly hydrolyzable analogue guanosine 5′-3-O-(thio)triphosphate (GTPγS). Moreover, the Npa3 mutant that binds GTP, but cannot hydrolyze it, binds RNAPII even in the absence of added GTP, whereas the mutant that cannot bind GTP is unable to bind the polymerase. Together, our data suggest that Npa3 defines an unconventional pathway for nuclear import of RNAPII, which involves GTP-dependent binding of Npa3 to the polymerase.

Key role of endothelial importin-α in VEGF expression and gastric angiogenesis: novel insight into aging gastropathy

2014 ◽  
Vol 306 (4) ◽  
pp. G338-G345 ◽  
Author(s):  
Amrita Ahluwalia ◽  
Michael K. Jones ◽  
Andrzej S. Tarnawski
Keyword(s):  
Nuclear Transport ◽  
Gene Activation ◽  
In Vivo Studies ◽  
Vegf Gene ◽  
Vegf Expression ◽  
Importin Α ◽  
In Vitro Angiogenesis ◽  
Impaired Angiogenesis

Recent in vivo studies demonstrated that aging gastric mucosa has impaired angiogenesis and reduced expression of vascular endothelial growth factor (VEGF). Angiogenesis is triggered by hypoxia and VEGF gene activation, and the latter requires transport of transcription factor(s) into endothelial cell nuclei. We focused on gastric mucosal endothelial cells (GMEC), which are key targets and effectors of gastric angiogenesis, and determined whether and to what extent importin-α, a nuclear transport protein, regulates VEGF gene activation and gastric angiogenesis and the possible role of importin-α in aging gastropathy. GMEC were isolated from rats 3 and 24 mo of age, young (YGEC) and aging (AGEC), respectively. We examined in these cells 1) in vitro angiogenesis, 2) expression of VEGF and importin-α, 3) nuclear transport of hypoxia-inducible factor (HIF)-1α by importin-α, 4) binding of HIF-1α to the VEGF gene promoter, and 5) effects of importin-α silencing in YGEC and its upregulation in AGEC on angiogenesis and VEGF expression. AGEC exhibited significantly impaired in vitro angiogenesis by fourfold and decreased expression of VEGF, importin-α, and nuclear HIF-1α by 1.4-fold, 1.6-fold, and 2.9-fold, respectively, vs. YGEC. Upregulation of importin-α in AGEC significantly reversed all these abnormalities. In YGEC, knockdown of importins-α1 and -α3 significantly reduced in vitro angiogenesis by 93% and 73% and VEGF expression by 48% and 52%, respectively. The above findings demonstrate that importin-α is a novel and critical regulator of gastric angiogenesis. Its reduced expression in AGEC is the key mechanism for impaired angiogenesis and reduced VEGF.

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