scholarly journals Nuclear transit of human zipcode-binding protein IMP1

2003 ◽  
Vol 376 (2) ◽  
pp. 383-391 ◽  
Author(s):  
Jacob NIELSEN ◽  
Sidsel K. ADOLPH ◽  
Ewa RAJPERT-De MEYTS ◽  
Jens LYKKE-ANDERSEN ◽  
Grete KOCH ◽  
...  
Keyword(s):  
Translational Control ◽  
Nuclear Export ◽  
Rna Binding ◽  
Binding Protein ◽  
Leptomycin B ◽  
Granule Formation ◽  
Rna Recognition Motifs ◽  
3T3 Fibroblasts ◽  
Recognition Motifs ◽  
Homology Domains

The human IMPs (insulin-like growth factor II mRNA-binding proteins) belong to a vertebrate zipcode-binding protein family consisting of two RNA recognition motifs and four K homology domains and have been implicated in cytoplasmic mRNA localization, turnover and translational control. In the present study, we show that IMP1 is capable of translocating into nuclei of NIH 3T3 fibroblasts and its immunoreactivity is present in the nuclei of human spermatogenic cells. IMP1 does not contain a simple import signal, but nuclear entry was facilitated by disruption of RNA binding and cytoplasmic granule formation. IMP1 contains two NESs (nuclear export signals) within the RNA-binding K homology domains 2 and 4. The former is a leucine-rich leptomycin B-sensitive NES, whereas the latter is a leptomycin B-insensitive NES. Taken together, these results indicate that IMP1 may attach to its target mRNAs in the nucleus and thereby define the cytoplasmic fate of the transcripts.

Structural properties and RNA-binding activities of two RNA recognition motifs of a mouse neural RNA-binding protein, mouse-Musashi-1

Gene ◽  
1997 ◽  
Vol 186 (1) ◽  
pp. 21-27 ◽  
Author(s):  
Yasuyuki Kurihara ◽  
Takashi Nagata ◽  
Takao Imai ◽  
Ado Hiwatashi ◽  
Masataka Horiuchi ◽  
...  
Keyword(s):  
Structural Properties ◽  
Rna Binding ◽  
Binding Protein ◽  
Rna Binding Protein ◽  
Rna Recognition ◽  
Rna Recognition Motifs ◽  
Recognition Motifs

scholarly journals Two ZBP1 KH domains facilitate β-actin mRNA localization, granule formation, and cytoskeletal attachment

2002 ◽  
Vol 160 (1) ◽  
pp. 77-87 ◽  
Author(s):  
Kim L. Farina ◽  
Stefan Hüttelmaier ◽  
Kiran Musunuru ◽  
Robert Darnell ◽  
Robert H. Singer
Keyword(s):  
Rna Binding ◽  
Leading Edge ◽  
Mrna Localization ◽  
Binding Studies ◽  
Granule Formation ◽  
Rna Recognition Motifs ◽  
Hnrnp K ◽  
Actin Mrna ◽  
Recognition Motifs ◽  
Localization Element

Chicken embryo fibroblasts (CEFs) localize β-actin mRNA to their lamellae, a process important for the maintenance of cell polarity and motility. The localization of β-actin mRNA requires a cis localization element (zipcode) and involves zipcode binding protein 1 (ZBP1), a protein that specifically binds to the zipcode. Both localize to the lamellipodia of polarized CEFs. ZBP1 and its homologues contain two NH2-terminal RNA recognition motifs (RRMs) and four COOH-terminal hnRNP K homology (KH) domains. By using ZBP1 truncations fused to GFP in conjunction with in situ hybridization analysis, we have determined that KH domains three and four were responsible for granule formation and cytoskeletal association. When the NH2 terminus was deleted, granules formed by the KH domains alone did not accumulate at the leading edge, suggesting a role for the NH2 terminus in targeting transport granules to their destination. RNA binding studies were used to show that the third and fourth KH domains, not the RRM domains, bind the zipcode of β-actin mRNA. Overexpression of the four KH domains or certain subsets of these domains delocalized β-actin mRNA in CEFs and inhibited fibroblast motility, demonstrating the importance of ZBP1 function in both β-actin mRNA localization and cell motility.

Cytoplasmic trafficking of IGF-II mRNA-binding protein by conserved KH domains

2002 ◽  
Vol 115 (10) ◽  
pp. 2087-2097 ◽  
Author(s):  
Finn C. Nielsen ◽  
Jacob Nielsen ◽  
Mette A. Kristensen ◽  
Grete Koch ◽  
Jan Christiansen
Keyword(s):  
Rna Binding ◽  
Leading Edge ◽  
Cortical Region ◽  
Structural Determinants ◽  
Granule Formation ◽  
Rna Recognition Motifs ◽  
Motile Cells ◽  
Recognition Motifs ◽  
Rnp Granules ◽  
Mrna Binding

The IGF-II mRNA-binding proteins (IMPs), which are composed of two RNA recognition motifs, (RRM) and four hnRNP K homology (KH) domains, have been implicated in subcytoplasmic localization of mRNAs during embryogenesis. The IMP family originated via two gene duplications before the divergence of vertebrates, and IMP homologues consisting of only the four KH motifs have been identified in Drosophila and Caenorhabditis elegans. Here we characterise the trafficking of GFP-IMP1 fusion proteins and determine the structural determinants for proper cytoplasmic localization. GFP-IMP1 is present in large 200-700 nm RNP granules, which are distributed along microtubules. In motile cells, GFP-IMP1 is transported towards the leading edge into the cortical region of the lamellipodia where it is connected to microfilaments. Granules travel in an ATP-dependent fashion at an average speed of 0.12 μm/s (range 0.04-0.22 μm/s), and cells switch from a delocalized to a localized pattern within 15-20 minutes. Both granule formation and localization are unaffected by removal of the two RRMs, whereas deletion of the KH domains, which mediate RNA-binding, impairs these functions. We conclude that IMP1 localization is associated with motility and that the major functions of IMP1 are carried out by the phylogenetically conserved KH domains.

scholarly journals Neural RNA-binding protein Musashi1 inhibits translation initiation by competing with eIF4G for PABP

2008 ◽  
Vol 181 (4) ◽  
pp. 639-653 ◽  
Author(s):  
Hironori Kawahara ◽  
Takao Imai ◽  
Hiroaki Imataka ◽  
Masafumi Tsujimoto ◽  
Ken Matsumoto ◽  
...  
Keyword(s):  
Stem Cells ◽  
Neural Stem Cells ◽  
Translation Initiation ◽  
Rna Binding ◽  
Binding Protein ◽  
Rna Binding Protein ◽  
Stress Granules ◽  
Translational Repression ◽  
Rna Recognition Motifs ◽  
Recognition Motifs

Musashi1 (Msi1) is an RNA-binding protein that is highly expressed in neural stem cells. We previously reported that Msi1 contributes to the maintenance of the immature state and self-renewal activity of neural stem cells through translational repression of m-Numb. However, its translation repression mechanism has remained unclear. Here, we identify poly(A) binding protein (PABP) as an Msi1-binding protein, and find Msi1 competes with eIF4G for PABP binding. This competition inhibits translation initiation of Msi1's target mRNA. Indeed, deletion of the PABP-interacting domain in Msi1 abolishes its function. We demonstrate that Msi1 inhibits the assembly of the 80S, but not the 48S, ribosome complex. Consistent with these conclusions, Msi1 colocalizes with PABP and is recruited into stress granules, which contain the stalled preinitiation complex. However, Msi1 with mutations in two RNA recognition motifs fails to accumulate into stress granules. These results provide insight into the mechanism by which sequence-specific translational repression occurs in stem cells through the control of translation initiation.

scholarly journals RNA-binding protein Maca is crucial for gigantic male fertility factor gene expression, spermatogenesis, and male fertility, in Drosophila

PLoS Genetics ◽  
2021 ◽  
Vol 17 (6) ◽  
pp. e1009655
Author(s):  
Li Zhu ◽  
Ryuya Fukunaga
Keyword(s):  
Gene Expression ◽  
Male Fertility ◽  
Rna Binding ◽  
Binding Protein ◽  
Rna Binding Protein ◽  
Large Male ◽  
Rna Recognition Motifs ◽  
Fertility Factor ◽  
Recognition Motifs ◽  
Successful Expression

During spermatogenesis, the process in which sperm for fertilization are produced from germline cells, gene expression is spatiotemporally highly regulated. In Drosophila, successful expression of extremely large male fertility factor genes on Y-chromosome spanning some megabases due to their gigantic intron sizes is crucial for spermatogenesis. Expression of such extremely large genes must be challenging, but the molecular mechanism that allows it remains unknown. Here we report that a novel RNA-binding protein Maca, which contains two RNA-recognition motifs, is crucial for this process. maca null mutant male flies exhibited a failure in the spermatid individualization process during spermatogenesis, lacked mature sperm, and were completely sterile, while maca mutant female flies were fully fertile. Proteomics and transcriptome analyses revealed that both protein and mRNA abundance of the gigantic male fertility factor genes kl-2, kl-3, and kl-5 (kl genes) are significantly decreased, where the decreases of kl-2 are particularly dramatic, in maca mutant testes. Splicing of the kl-3 transcripts was also dysregulated in maca mutant testes. All these physiological and molecular phenotypes were rescued by a maca transgene in the maca mutant background. Furthermore, we found that in the control genetic background, Maca is exclusively expressed in spermatocytes in testes and enriched at Y-loop A/C in the nucleus, where the kl-5 primary transcripts are localized. Our data suggest that Maca increases transcription processivity, promotes successful splicing of gigantic introns, and/or protects transcripts from premature degradation, of the kl genes. Our study identified a novel RNA-binding protein Maca that is crucial for successful expression of the gigantic male fertility factor genes, spermatogenesis, and male fertility.

scholarly journals Nuclear RNA binding regulates TDP-43 nuclear localization and passive nuclear export

2021 ◽  
Author(s):  
Lauren Duan ◽  
Benjamin L. Zaepfel ◽  
Vasilisa Aksenova ◽  
Mary Dasso ◽  
Jeffrey D. Rothstein ◽  
...  
Keyword(s):  
Nuclear Localization ◽  
Nuclear Export ◽  
Rna Binding ◽  
Nuclear Accumulation ◽  
Nuclear Pore ◽  
Nuclear Retention ◽  
Rna Recognition Motifs ◽  
Nuclear Abundance ◽  
Recognition Motifs

AbstractNuclear clearance of the DNA/RNA-binding protein TDP-43 is a pathologic hallmark of amyotrophic lateral sclerosis and frontotemporal dementia that remains unexplained. Moreover, our current understanding of TDP-43 nucleocytoplasmic shuttling does not fully explain the predominantly nuclear localization of TDP-43 in healthy cells. Here, we used permeabilized and live-cell models to investigate TDP-43 nuclear export and the role of RNA in TDP-43 localization. We show that TDP-43 nuclear efflux occurs in low-ATP conditions and independent of active mRNA export, consistent with export by passive diffusion through nuclear pore channels. TDP-43 nuclear residence requires binding to GU-rich nuclear intronic pre-mRNAs, based on the induction of TDP-43 nuclear efflux by RNase and GU-rich oligomers and TDP-43 nuclear retention conferred by pre-mRNA splicing inhibitors. Mutation of TDP-43 RNA recognition motifs disrupts TDP-43 nuclear accumulation and abolishes transcriptional blockade-induced TDP-43 nuclear efflux, demonstrating strict dependence of TDP-43 nuclear localization on RNA binding. Thus, the nuclear abundance of GU-rich intronic pre-mRNAs, as dictated by the balance of transcription and pre-mRNA processing, regulates TDP-43 nuclear sequestration and availability for passive nuclear export.

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