scholarly journals Production of functional small interfering RNAs by an amino-terminal deletion mutant of human Dicer

2015 ◽  
Vol 112 (50) ◽  
pp. E6945-E6954 ◽  
Author(s):  
Edward M. Kennedy ◽  
Adam W. Whisnant ◽  
Anand V. R. Kornepati ◽  
Joy B. Marshall ◽  
Hal P. Bogerd ◽  
...  
Keyword(s):  
Influenza A ◽  
Human Cells ◽  
Helicase Domain ◽  
Mutant Form ◽  
Small Interfering Rnas ◽  
Double Knockout ◽  
Double Stranded Rna ◽  
Amino Terminal ◽  
Rnai Response ◽  
Cognate Mrnas

Although RNA interference (RNAi) functions as a potent antiviral innate-immune response in plants and invertebrates, mammalian somatic cells appear incapable of mounting an RNAi response and few, if any, small interfering RNAs (siRNAs) can be detected. To examine why siRNA production is inefficient, we have generated double-knockout human cells lacking both Dicer and protein kinase RNA-activated. Using these cells, which tolerate double-stranded RNA expression, we show that a mutant form of human Dicer lacking the amino-terminal helicase domain can process double-stranded RNAs to produce high levels of siRNAs that are readily detectable by Northern blot, are loaded into RNA-induced silencing complexes, and can effectively and specifically inhibit the expression of cognate mRNAs. Remarkably, overexpression of this mutant Dicer, but not wild-type Dicer, also resulted in a partial inhibition of Influenza A virus—but not poliovirus—replication in human cells.

scholarly journals The Significance of the DUF283 Domain for the Activity of Human Ribonuclease Dicer

2021 ◽  
Vol 22 (16) ◽  
pp. 8690
Author(s):  
Agnieszka Szczepanska ◽  
Marta Wojnicka ◽  
Anna Kurzynska-Kokorniak
Keyword(s):  
Amino Acid ◽  
Biochemical Characterization ◽  
Helicase Domain ◽  
Small Interfering Rnas ◽  
Base Pairing ◽  
Stem Loop ◽  
Deletion Variant ◽  
Amino Terminal ◽  
Complementary Rnas

Dicers are multidomain proteins, usually comprising an amino-terminal putative helicase domain, a DUF283 domain (domain of unknown function), a PAZ domain, two RNase III domains (RNase IIIa and RNase IIIb) and a dsRNA-binding domain. Dicer homologs play an important role in the biogenesis of small regulatory RNAs by cleaving single-stranded precursors adopting stem-loop structures (pre-miRNAs) and double-strand RNAs into short RNA duplexes containing functional microRNAs or small interfering RNAs, respectively. Growing evidence shows that apart from the canonical role, Dicer proteins can serve a number of other functions. For example, results of our previous studies showed that human Dicer (hDicer), presumably through its DUF283 domain, can facilitate hybridization between two complementary RNAs, thus, acting as a nucleic acid annealer. Here, to test this assumption, we prepared a hDicer deletion variant lacking the amino acid residues 625-752 corresponding to the DUF283 domain. The respective 128-amino acid fragment of hDicer was earlier demonstrated to accelerate base-pairing between two complementary RNAs in vitro. We show that the ΔDUF(625-752) hDicer variant loses the potential to facilitate RNA-RNA base pairing, which strongly proves our hypothesis about the importance of the DUF283 domain for the RNA-RNA annealing activity of hDicer. Interestingly, the in vitro biochemical characterization of the obtained deletion variant reveals that it displays different RNA cleavage properties depending on the pre-miRNA substrate.

scholarly journals RTEL1 influences the abundance and localization of TERRA RNA

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Fiorella Ghisays ◽  
Aitor Garzia ◽  
Hexiao Wang ◽  
Claudia Canasto-Chibuque ◽  
Marcel Hohl ◽  
...  
Keyword(s):  
Cell Viability ◽  
Telomere Length ◽  
Human Cells ◽  
Helicase Domain ◽  
Telomere Repeat ◽  
Disease Phenotypes ◽  
G Quadruplex ◽  
Non Coding Rnas ◽  
Subtelomeric Regions

AbstractTelomere repeat containing RNAs (TERRAs) are a family of long non-coding RNAs transcribed from the subtelomeric regions of eukaryotic chromosomes. TERRA transcripts can form R-loops at chromosome ends; however the importance of these structures or the regulation of TERRA expression and retention in telomeric R-loops remain unclear. Here, we show that the RTEL1 (Regulator of Telomere Length 1) helicase influences the abundance and localization of TERRA in human cells. Depletion of RTEL1 leads to increased levels of TERRA RNA while reducing TERRA-containing R loops at telomeres. In vitro, RTEL1 shows a strong preference for binding G-quadruplex structures which form in TERRA. This binding is mediated by the C-terminal region of RTEL1, and is independent of the RTEL1 helicase domain. RTEL1 binding to TERRA appears to be essential for cell viability, underscoring the importance of this function. Degradation of TERRA-containing R-loops by overexpression of RNAse H1 partially recapitulates the increased TERRA levels and telomeric instability associated with RTEL1 deficiency. Collectively, these data suggest that regulation of TERRA is a key function of the RTEL1 helicase, and that loss of that function may contribute to the disease phenotypes of patients with RTEL1 mutations.

scholarly journals Analysis of the Interaction of Primate Retroviruses with the Human RNA Interference Machinery

2007 ◽  
Vol 81 (22) ◽  
pp. 12218-12226 ◽  
Author(s):  
Jennifer Lin ◽  
Bryan R. Cullen
Keyword(s):  
Rna Interference ◽  
Virus Type ◽  
Leukemia Virus ◽  
Foamy Virus ◽  
Human Cells ◽  
Small Interfering Rnas ◽  
Cell Leukemia Virus Type ◽  
Human T Cell ◽  
Hiv 1

ABSTRACT The question of whether retroviruses, including human immunodeficiency virus type 1 (HIV-1), interact with the cellular RNA interference machinery has been controversial. Here, we present data showing that neither HIV-1 nor human T-cell leukemia virus type 1 (HTLV-1) expresses significant levels of either small interfering RNAs or microRNAs in persistently infected T cells. We also demonstrate that the retroviral nuclear transcription factors HIV-1 Tat and HTLV-1 Tax, as well as the Tas transactivator encoded by primate foamy virus, fail to inhibit RNA interference in human cells. Moreover, the stable expression of physiological levels of HIV-1 Tat did not globally inhibit microRNA production or expression in infected human cells. Together, these data argue that HIV-1 and HTLV-1 neither induce the production of viral small interfering RNAs or microRNAs nor repress the cellular RNA interference machinery in infected cells.

Surface expression of influenza virus neuraminidase, an amino-terminally anchored viral membrane glycoprotein, in polarized epithelial cells

1985 ◽  
Vol 5 (9) ◽  
pp. 2181-2189
Author(s):  
L V Jones ◽  
R W Compans ◽  
A R Davis ◽  
T J Bos ◽  
D P Nayak
Keyword(s):  
Influenza Virus ◽  
Influenza A ◽  
Surface Expression ◽  
African Green Monkey ◽  
Monkey Kidney ◽  
Kidney Cells ◽  
African Green Monkey Kidney ◽  
Amino Terminal ◽  
Green Monkey ◽  
Na Gene

We have investigated the site of surface expression of the neuraminidase (NA) glycoprotein of influenza A virus, which, in contrast to the hemagglutinin, is bound to membranes by hydrophobic residues near the NH2-terminus. Madin-Darby canine kidney or primary African green monkey kidney cells infected with influenza A/WSN/33 virus and subsequently labeled with monoclonal antibody to the NA and then with a colloidal gold- or ferritin-conjugated second antibody exhibited specific labeling of apical surfaces. Using simian virus 40 late expression vectors, we also studied the surface expression of the complete NA gene (SNC) and a truncated NA gene (SN10) in either primary or a polarized continuous line (MA104) of African green monkey kidney cells. The polypeptides encoded by the cloned NA cDNAs were expressed on the surface of both cell types. Analysis of [3H]mannose-labeled polypeptides from recombinant virus-infected MA104 cells showed that the products of cloned NA cDNA comigrated with glycosylated NA from influenza virus-infected cells. Both the complete and the truncated glycoproteins were found to be preferentially expressed on apical plasma membranes, as detected by immunogold labeling. These results indicate that the NA polypeptide contains structural features capable of directing the transport of the protein to apical cell surfaces and the first 10 amino-terminal residues of the NA polypeptide are not involved in this process.

scholarly journals The Cellular RNA Helicase UAP56 Is Required for Prevention of Double-Stranded RNA Formation during Influenza A Virus Infection

2011 ◽  
Vol 85 (17) ◽  
pp. 8646-8655 ◽  
Author(s):  
C. Wisskirchen ◽  
T. H. Ludersdorfer ◽  
D. A. Muller ◽  
E. Moritz ◽  
J. Pavlovic
Keyword(s):  
Virus Infection ◽  
Influenza A Virus ◽  
Influenza A ◽  
Rna Helicase ◽  
Double Stranded Rna ◽  
Influenza A Virus Infection ◽  
Rna Formation

scholarly journals Phytophthora effector targets a novel component of small RNA pathway in plants to promote infection

2015 ◽  
Vol 112 (18) ◽  
pp. 5850-5855 ◽  
Author(s):  
Yongli Qiao ◽  
Jinxia Shi ◽  
Yi Zhai ◽  
Yingnan Hou ◽  
Wenbo Ma
Keyword(s):  
Small Rna ◽  
Rna Silencing ◽  
Effector Proteins ◽  
Helicase Domain ◽  
Small Interfering Rnas ◽  
Developmental Defects ◽  
Interacting Protein ◽  
Homologous Genes ◽  
Unidentified Component ◽  
Virulence Target

A broad range of parasites rely on the functions of effector proteins to subvert host immune response and facilitate disease development. The notorious Phytophthora pathogens evolved effectors with RNA silencing suppression activity to promote infection in plant hosts. Here we report that the Phytophthora Suppressor of RNA Silencing 1 (PSR1) can bind to an evolutionarily conserved nuclear protein containing the aspartate–glutamate–alanine–histidine-box RNA helicase domain in plants. This protein, designated PSR1-Interacting Protein 1 (PINP1), regulates the accumulation of both microRNAs and endogenous small interfering RNAs in Arabidopsis. A null mutation of PINP1 causes embryonic lethality, and silencing of PINP1 leads to developmental defects and hypersusceptibility to Phytophthora infection. These phenotypes are reminiscent of transgenic plants expressing PSR1, supporting PINP1 as a direct virulence target of PSR1. We further demonstrate that the localization of the Dicer-like 1 protein complex is impaired in the nucleus of PINP1-silenced or PSR1-expressing cells, indicating that PINP1 may facilitate small RNA processing by affecting the assembly of dicing complexes. A similar function of PINP1 homologous genes in development and immunity was also observed in Nicotiana benthamiana. These findings highlight PINP1 as a previously unidentified component of RNA silencing that regulates distinct classes of small RNAs in plants. Importantly, Phytophthora has evolved effectors to target PINP1 in order to promote infection.

scholarly journals Human IFITM3 restricts Chikungunya virus and Mayaro virus infection and is susceptible to virus-mediated counteraction

2020 ◽  
Author(s):  
Sergej Franz ◽  
Thomas Zillinger ◽  
Fabian Pott ◽  
Christiane Schüler ◽  
Sandra Dapa ◽  
...  
Keyword(s):  
Virus Infection ◽  
Influenza A ◽  
Chikungunya Virus ◽  
Protein S ◽  
Human Cells ◽  
Structural Protein ◽  
Infected Cells ◽  
Mayaro Virus ◽  
The Impact

AbstractInterferon-induced transmembrane (IFITM) proteins restrict infection by enveloped viruses through interfering with membrane fusion and virion internalisation. The role of IFITM proteins during alphaviral infection of human cells and viral counteraction strategies remain largely unexplored. Here, we characterized the impact of IFITM proteins and variants on entry and spread of Chikungunya virus (CHIKV) and Mayaro virus (MAYV) in human cells, and provide first evidence for a CHIKV-mediated antagonism of IFITM proteins. IFITM1, 2 and 3 restricted infection at the level of alphavirus glycoprotein-mediated entry, both in the context of direct infection and during cell-to-cell transmission. Relocalization of normally endosomal IFITM3 to the plasma membrane resulted in the loss of its antiviral activity. rs12252-C, a naturally occurring variant of IFITM3 that has been proposed to associate with severe influenza in humans, restricted CHIKV, MAYV and influenza A virus infection as efficiently as wild-type IFITM3. Finally, all antivirally active IFITM variants displayed reduced cell surface levels in CHIKV-infected cells involving a posttranscriptional process mediated by one or several non-structural protein(s) of CHIKV.

scholarly journals E. coli OxyS non-coding RNA does not trigger RNAi in C. elegans

2014 ◽  
Author(s):  
Alper Akay ◽  
Peter Sarkies ◽  
Eric Alexander Miska
Keyword(s):  
Small Rnas ◽  
Biological Function ◽  
Rapid Development ◽  
Rnai Pathway ◽  
Regulate Gene Expression ◽  
Double Stranded Rna ◽  
E Coli ◽  
C Elegans ◽  
Non Coding Rna ◽  
Rnai Response

The discovery of RNA interference (RNAi) in C. elegans has had a major impact on scientific research, led to the rapid development of RNAi tools and has inspired RNA-based therapeutics. Astonishingly, nematodes, planaria and many insects take up double-stranded RNA (dsRNA) from their environment to elicit RNAi; the biological function of this mechanism is unclear. Recently, the E. coli OxyS non-coding RNA was shown to regulate gene expression in C. elegans when E. coli is offered as food. This was surprising given that C. elegans is unlikely to encounter E. coli in nature. To directly test the hypothesis that the E. coli OxyS non-coding RNA triggers the C. elegans RNAi pathway, we sequenced small RNAs from C. elegans after feeding with bacteria. We clearly demonstrate that the OxyS non-coding RNA does not trigger an RNAi response in C. elegans. We conclude that the biology of environmental RNAi remains to be discovered.

scholarly journals Unknown Areas of Activity of Human Ribonuclease Dicer: A Putative Deoxyribonuclease Activity

Molecules ◽  
2020 ◽  
Vol 25 (6) ◽  
pp. 1414 ◽  
Author(s):  
Marta Wojnicka ◽  
Agnieszka Szczepanska ◽  
Anna Kurzynska-Kokorniak
Keyword(s):  
Dnase Activity ◽  
Helicase Domain ◽  
Small Interfering Rnas ◽  
Rnase Iii ◽  
Domain Specific ◽  
Dsrna Binding ◽  
Small Regulatory Rnas ◽  
Paz Domain ◽  
Canonical Products ◽  
Truncated Variants

The Dicer ribonuclease plays a crucial role in the biogenesis of small regulatory RNAs (srRNAs) by processing long double-stranded RNAs and single-stranded hairpin RNA precursors into small interfering RNAs (siRNAs) and microRNAs (miRNAs), respectively. Dicer-generated srRNAs can control gene expression by targeting complementary transcripts and repressing their translation or inducing their cleavage. Human Dicer (hDicer) is a multidomain enzyme comprising a putative helicase domain, a DUF283 domain, platform, a PAZ domain, a connector helix, two RNase III domains (RNase IIIa and RNase IIIb) and a dsRNA-binding domain. Specific, ~20-base pair siRNA or miRNA duplexes with 2 nucleotide (nt) 3’-overhangs are generated by Dicer when an RNA substrate is anchored within the platform-PAZ-connector helix (PPC) region. However, increasing number of reports indicate that in the absence of the PAZ domain, binding of RNA substrates can occur by other Dicer domains. Interestingly, truncated variants of Dicer, lacking the PPC region, have been found to display a DNase activity. Inspired by these findings, we investigated how the lack of the PAZ domain, or the entire PPC region, would influence the cleavage activity of hDicer. Using immunopurified 3xFlag-hDicer produced in human cells and its two variants: one lacking the PAZ domain, and the other lacking the entire PPC region, we show that the PAZ domain deletion variants of hDicer are not able to process a pre-miRNA substrate, a dsRNA with 2-nt 3ʹ-overhangs, and a blunt-ended dsRNA. However, the PAZ deletion variants exhibit both RNase and DNase activity on short single-stranded RNA and DNAs, respectively. Collectively, our results indicate that when the PAZ domain is absent, other hDicer domains may contribute to substrate binding and in this case, non-canonical products can be generated.

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