scholarly journals Unique Features of Plant Cleavage and Polyadenylation Specificity Factor Revealed by Proteomic Studies

2009 ◽  
Vol 151 (3) ◽  
pp. 1546-1556 ◽  
Author(s):  
Hongwei Zhao ◽  
Denghui Xing ◽  
Qingshun Quinn Li
Keyword(s):  
Cleavage And Polyadenylation ◽  
Specificity Factor

scholarly journals The HIV-1 capsid-binding host factor CPSF6 is post-transcriptionally regulated by the cellular microRNA miR-125b

2020 ◽  
Vol 295 (15) ◽  
pp. 5081-5094
Author(s):  
Evan Chaudhuri ◽  
Sabyasachi Dash ◽  
Muthukumar Balasubramaniam ◽  
Adrian Padron ◽  
Joseph Holland ◽  
...  
Keyword(s):  
Molecular Mechanisms ◽  
Mammalian Species ◽  
Cellular Protein ◽  
Luciferase Reporter ◽  
Down Regulation ◽  
Host Interaction ◽  
Cleavage And Polyadenylation ◽  
Specificity Factor ◽  
Viral Dna Integration ◽  
Hiv 1

Cleavage and polyadenylation specificity factor 6 (CPSF6) is a cellular protein involved in mRNA processing. Emerging evidence suggests that CPSF6 also plays key roles in HIV-1 infection, specifically during nuclear import and integration targeting. However, the cellular and molecular mechanisms that regulate CPSF6 expression are largely unknown. In this study, we report a post-transcriptional mechanism that regulates CPSF6 via the cellular microRNA miR-125b. An in silico analysis revealed that the 3′UTR of CPSF6 contains a miR-125b–binding site that is conserved across several mammalian species. Because miRNAs repress protein expression, we tested the effects of miR-125b expression on CPSF6 levels in miR-125b knockdown and over-expression experiments, revealing that miR-125b and CPSF6 levels are inversely correlated. To determine whether miR-125b post-transcriptionally regulates CPSF6, we introduced the 3′UTR of CPSF6 mRNA into a luciferase reporter and found that miR-125b negatively regulates CPSF6 3′UTR-driven luciferase activity. Accordingly, mutations in the miR-125b seed sequence abrogated the regulatory effect of the miRNA on the CPSF6 3′UTR. Finally, pulldown experiments demonstrated that miR-125b physically interacts with CPSF6 3′UTR. Interestingly, HIV-1 infection down-regulated miR-125b expression concurrent with up-regulation of CPSF6. Notably, miR-125b down-regulation in infected cells was not due to reduced pri-miRNA or pre-miRNA levels. However, miR-125b down-regulation depended on HIV-1 reverse transcription but not viral DNA integration. These findings establish a post-transcriptional mechanism that controls CPSF6 expression and highlight a novel function of miR-125b during HIV-host interaction.

scholarly journals The Cleavage and Polyadenylation Specificity Factor in Xenopus laevis Oocytes Is a Cytoplasmic Factor Involved in Regulated Polyadenylation

1999 ◽  
Vol 19 (8) ◽  
pp. 5707-5717 ◽  
Author(s):  
Kirsten S. Dickson ◽  
Andrea Bilger ◽  
Scott Ballantyne ◽  
Marvin P. Wickens
Keyword(s):  
Xenopus Laevis ◽  
Bos Taurus ◽  
Xenopus Laevis Oocytes ◽  
Ns1 Protein ◽  
Amino Acid Sequence Level ◽  
Cytoplasmic Factor ◽  
Cytoplasmic Polyadenylation ◽  
Cleavage And Polyadenylation ◽  
Specificity Factor

ABSTRACT During early development, specific mRNAs receive poly(A) in the cytoplasm. This cytoplasmic polyadenylation reaction correlates with, and in some cases causes, translational stimulation. Previously, it was suggested that a factor similar to the multisubunit nuclear cleavage and polyadenylation specificity factor (CPSF) played a role in cytoplasmic polyadenylation. A cDNA encoding a cytoplasmic form of the 100-kDa subunit of Xenopus laevis CPSF has now been isolated. The protein product is 91% identical at the amino acid sequence level to nuclear CPSF isolated from Bos taurusthymus. This report provides three lines of evidence that implicate theX. laevis homologue of the 100-kDa subunit of CPSF in the cytoplasmic polyadenylation reaction. First, the protein is predominantly localized to the cytoplasm of X. laevisoocytes. Second, the 100-kDa subunit of X. laevis CPSF forms a specific complex with RNAs that contain both a cytoplasmic polyadenylation element (CPE) and the polyadenylation element AAUAAA. Third, immunodepletion of the 100-kDa subunit ofX. laevis CPSF reduces CPE-specific polyadenylation in vitro. Further support for a cytoplasmic form of CPSF comes from evidence that a putative homologue of the 30-kDa subunit of nuclear CPSF is also localized to the cytoplasm of X. laevisoocytes. Overexpression of influenza virus NS1 protein, which inhibits nuclear polyadenylation through an interaction with the 30-kDa subunit of nuclear CPSF, prevents cytoplasmic polyadenylation, suggesting that the cytoplasmic X. laevis form of the 30-kDa subunit of CPSF is involved in this reaction. Together, these results indicate that a distinct, cytoplasmic form of CPSF is an integral component of the cytoplasmic polyadenylation machinery.

scholarly journals Cleavage and polyadenylation specificity factor 30: An RNA-binding zinc-finger protein with an unexpected 2Fe–2S cluster

2016 ◽  
Vol 113 (17) ◽  
pp. 4700-4705 ◽  
Author(s):  
Geoffrey D. Shimberg ◽  
Jamie L. Michalek ◽  
Abdulafeez A. Oluyadi ◽  
Andria V. Rodrigues ◽  
Beth E. Zucconi ◽  
...  
Keyword(s):  
Zinc Finger ◽  
Inductively Coupled Plasma ◽  
Rna Binding ◽  
Zinc Finger Protein ◽  
Mobility Shift ◽  
Inductively Coupled ◽  
Plasma Mass Spectrometry ◽  
Cleavage And Polyadenylation ◽  
Specificity Factor ◽  
Electrophoretic Mobility Shift Assays

Cleavage and polyadenylation specificity factor 30 (CPSF30) is a key protein involved in pre-mRNA processing. CPSF30 contains five Cys3His domains (annotated as “zinc-finger” domains). Using inductively coupled plasma mass spectrometry, X-ray absorption spectroscopy, and UV-visible spectroscopy, we report that CPSF30 is isolated with iron, in addition to zinc. Iron is present in CPSF30 as a 2Fe–2S cluster and uses one of the Cys3His domains; 2Fe–2S clusters with a Cys3His ligand set are rare and notably have also been identified in MitoNEET, a protein that was also annotated as a zinc finger. These findings support a role for iron in some zinc-finger proteins. Using electrophoretic mobility shift assays and fluorescence anisotropy, we report that CPSF30 selectively recognizes the AU-rich hexamer (AAUAAA) sequence present in pre-mRNA, providing the first molecular-based evidence to our knowledge for CPSF30/RNA binding. Removal of zinc, or both zinc and iron, abrogates binding, whereas removal of just iron significantly lessens binding. From these data we propose a model for RNA recognition that involves a metal-dependent cooperative binding mechanism.

scholarly journals Symplekin, a Constitutive Protein of Karyo- and Cytoplasmic Particles Involved in mRNA Biogenesis in Xenopus laevisOocytes

2002 ◽  
Vol 13 (5) ◽  
pp. 1665-1676 ◽  
Author(s):  
Ilse Hofmann ◽  
Martina Schnölzer ◽  
Isabelle Kaufmann ◽  
Werner W. Franke
Keyword(s):  
Immunofluorescence Microscopy ◽  
Protein Complexes ◽  
Gradient Centrifugation ◽  
Stage Iv ◽  
Cell Junctions ◽  
Xenopus Laevis Oocytes ◽  
Mrna Metabolism ◽  
Egg Extracts ◽  
Cleavage And Polyadenylation ◽  
Specificity Factor

Symplekin is a dual location protein that has been localized to the cytoplasmic plaques of tight junctions but also occurs in the form of interchromatin particles in the karyoplasm. Here we report the identification of two novel and major symplekin-containing protein complexes in both the karyo- and the cytoplasm of Xenopus laevis oocytes. Buffer-extractable fractions from the karyoplasm of stage IV–VI oocytes contain an 11S particle, prepared by immunoselection and sucrose gradient centrifugation, in which symplekin is associated with the subunits of the cleavage and polyadenylation specificity factor (CPSF). Moreover, in immunofluorescence microscopy nuclear symplekin colocalizes with protein CPSF-100 in the “Cajal bodies.” However, symplekin is also found in cytoplasmic extracts of enucleated oocytes and egg extracts, where it occurs in 11S as well as in ca. 65S particles, again in association with CPSF-100. This suggests that, in X. laevis oocytes, symplekin is possibly involved in both processes, 3′-end processing of pre-mRNA in the nucleus and regulated polyadenylation in the cytoplasm. We discuss the possible occurrence of similar symplekin-containing particles involved in mRNA metabolism in the nucleus and cytoplasm of other kinds of cells, also in comparison with the nuclear forms of other dual location proteins in nuclei and cell junctions.

scholarly journals HIV-1 replication complexes accumulate in nuclear speckles and integrate into speckle-associated genomic domains

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Ashwanth C. Francis ◽  
Mariana Marin ◽  
Parmit K. Singh ◽  
Vasudevan Achuthan ◽  
Mathew J. Prellberg ◽  
...  
Keyword(s):  
Viral Replication ◽  
Nuclear Import ◽  
Integration Site ◽  
Nuclear Speckles ◽  
Nuclear Entry ◽  
Primary Monocyte ◽  
Integration Sites ◽  
Cleavage And Polyadenylation ◽  
Specificity Factor ◽  
Hiv 1

AbstractThe early steps of HIV-1 infection, such as uncoating, reverse transcription, nuclear import, and transport to integration sites are incompletely understood. Here, we imaged nuclear entry and transport of HIV-1 replication complexes in cell lines, primary monocyte-derived macrophages (MDMs) and CD4+ T cells. We show that viral replication complexes traffic to and accumulate within nuclear speckles and that these steps precede the completion of viral DNA synthesis. HIV-1 transport to nuclear speckles is dependent on the interaction of the capsid proteins with host cleavage and polyadenylation specificity factor 6 (CPSF6), which is also required to stabilize the association of the viral replication complexes with nuclear speckles. Importantly, integration site analyses reveal a strong preference for HIV-1 to integrate into speckle-associated genomic domains. Collectively, our results demonstrate that nuclear speckles provide an architectural basis for nuclear homing of HIV-1 replication complexes and subsequent integration into associated genomic loci.

scholarly journals A potent antimalarial benzoxaborole targets a Plasmodium falciparum cleavage and polyadenylation specificity factor homologue

2017 ◽  
Vol 8 (1) ◽  
Author(s):  
Ebere Sonoiki ◽  
Caroline L. Ng ◽  
Marcus C. S. Lee ◽  
Denghui Guo ◽  
Yong-Kang Zhang ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Cleavage And Polyadenylation ◽  
Specificity Factor
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