Control of HIV-1 gene expression by SR proteins

2016 ◽  
Vol 44 (5) ◽  
pp. 1417-1425 ◽  
Author(s):  
Charlotte Mahiet ◽  
Chad M. Swanson
Keyword(s):  
Gene Expression ◽  
Nuclear Export ◽  
Rna Splicing ◽  
Drug Targets ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Antiviral Drug ◽  
Sr Proteins ◽  
Immunodeficiency Virus ◽  
Hiv 1

Cellular proteins are required for all steps of human immunodeficiency virus type 1 (HIV-1) gene expression including transcription, splicing, 3′-end formation/polyadenylation, nuclear export and translation. SR proteins are a family of cellular RNA-binding proteins that regulate and functionally integrate multiple steps of gene expression. Specific SR proteins are best characterised for regulating HIV-1 RNA splicing by binding specific locations in the viral RNA, though recently they have also been shown to control transcription, 3′-end formation, and translation. Due to their importance in regulating HIV-1 gene expression, SR proteins and their regulatory factors are potential antiviral drug targets.

scholarly journals Nucleo-cytoplasmic shuttling of splicing factor SRSF1 is required for development and cilia function

2020 ◽  
Author(s):  
Fiona Haward ◽  
Magdalena M. Maslon ◽  
Patricia L. Yeyati ◽  
Nicolas Bellora ◽  
Jan N. Hansen ◽  
...  
Keyword(s):  
Gene Expression ◽  
Mouse Model ◽  
Rna Splicing ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Small Body ◽  
Splicing Factor ◽  
Nuclear Retention ◽  
Ciliary Ultrastructure ◽  
Retention Signal

AbstractShuttling RNA-binding proteins coordinate nuclear and cytoplasmic steps of gene expression. The SR family proteins regulate RNA splicing in the nucleus and a subset of them, including SRSF1, shuttles between the nucleus and cytoplasm affecting post-splicing processes. However, the physiological significance of this remains unclear. Here, we used genome editing to knock-in a nuclear retention signal (NRS) in Srsf1 to create a mouse model harboring an SRSF1 protein that is retained exclusively in the nucleus. Srsf1NRS/NRS mutants displayed small body size, hydrocephalus and immotile sperm, all traits associated with ciliary defects. We observed reduced translation of a subset of mRNAs and decreased abundance of proteins involved in multiciliogenesis, with disruption of ciliary ultrastructure and motility in cells derived from this mouse model. These results demonstrate that SRSF1 shuttling is used to reprogram gene expression networks in the context of high cellular demands, as observed here, during motile ciliogenesis.

scholarly journals HIV-1 remodels the nuclear pore complex

2011 ◽  
Vol 193 (4) ◽  
pp. 619-631 ◽  
Author(s):  
Anne Monette ◽  
Nelly Panté ◽  
Andrew J. Mouland
Keyword(s):  
Nuclear Export ◽  
Cell Biology ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Immunogold Electron Microscopy ◽  
Nuclear Pore ◽  
Viral Control ◽  
Host Cell Proteins ◽  
Associated Proteins ◽  
Hiv 1

Human immunodeficiency virus type 1 (HIV-1) commandeers host cell proteins and machineries for its replication. Our earlier work showed that HIV-1 induced the cytoplasmic retention of nucleocytoplasmic shuttling and ribonucleic acid (RNA)–binding proteins. This retention is dependent on nuclear export of the viral genomic RNA and on changes in the localization and expression level of the nucleoporin (Nup) p62 (Nup62). To further characterize the extent of perturbation induced by HIV-1, we performed proteomics analyses of nuclear envelopes (NEs) isolated from infected T cells. Infection induced extensive changes in the composition of the NE and its associated proteins, including a remarkable decrease in the abundance of Nups. Immunogold electron microscopy revealed the translocation of Nups into the cytoplasm. Nup62 was identified as a component of purified virus, and small interfering RNA depletion studies revealed an important role for this Nup in virus gene expression and infectivity. This detailed analysis highlights the profound effects on NE composition induced by HIV-1 infection, providing further evidence of the magnitude of viral control over the cell biology of its host.

scholarly journals SRp40 and SRp55 Promote the Translation of Unspliced Human Immunodeficiency Virus Type 1 RNA

2010 ◽  
Vol 84 (13) ◽  
pp. 6748-6759 ◽  
Author(s):  
Chad M. Swanson ◽  
Nathan M. Sherer ◽  
Michael H. Malim
Keyword(s):  
Human Immunodeficiency Virus ◽  
Human Immunodeficiency Virus Type ◽  
Virus Type ◽  
Nuclear Export ◽  
Sr Proteins ◽  
Rna Recognition Motif ◽  
Genomic Rnas ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Nuclear RNA processing events, such as 5′ cap formation, 3′ polyadenylation, and pre-mRNA splicing, mark mRNA for efficient translation. Splicing enhances translation via the deposition of the exon-junction complex and other multifunctional splicing factors, including SR proteins. All retroviruses synthesize their structural and enzymatic proteins from unspliced genomic RNAs (gRNAs) and must therefore exploit unconventional strategies to ensure their effective expression. Here, we report that specific SR proteins, particularly SRp40 and SRp55, promote human immunodeficiency virus type 1 (HIV-1) Gag translation from unspliced (intron-containing) viral RNA. This activity does not correlate with nucleocytoplasmic shuttling capacity and, in the case of SRp40, is dependent on the second RNA recognition motif and the arginine-serine (RS) domain. While SR proteins enhance Gag expression independent of RNA nuclear export pathway choice, altering the nucleotide sequence of the gag-pol coding region by codon optimization abolishes this effect. We therefore propose that SR proteins couple HIV-1 gRNA biogenesis to translational utilization.

scholarly journals Nuclear Export Signal Masking Regulates HIV-1 Rev Trafficking and Viral RNA Nuclear Export

2016 ◽  
Vol 91 (3) ◽  
Author(s):  
Ryan T. Behrens ◽  
Mounavya Aligeti ◽  
Ginger M. Pocock ◽  
Christina A. Higgins ◽  
Nathan M. Sherer
Keyword(s):  
Gene Expression ◽  
Nuclear Export ◽  
Rna Binding ◽  
Nuclear Export Signal ◽  
Viral Gene Expression ◽  
Viral Gene ◽  
Virion Production ◽  
Export Signal ◽  
Hiv 1 ◽  
Rev Protein

ABSTRACT HIV-1's Rev protein forms a homo-oligomeric adaptor complex linking viral RNAs to the cellular CRM1/Ran-GTP nuclear export machinery through the activity of Rev's prototypical leucine-rich nuclear export signal (NES). In this study, we used a functional fluorescently tagged Rev fusion protein as a platform to study the effects of modulating Rev NES identity, number, position, or strength on Rev subcellular trafficking, viral RNA nuclear export, and infectious virion production. We found that Rev activity was remarkably tolerant of diverse NES sequences, including supraphysiological NES (SNES) peptides that otherwise arrest CRM1 transport complexes at nuclear pores. Rev's ability to tolerate a SNES was both position and multimerization dependent, an observation consistent with a model wherein Rev self-association acts to transiently mask the NES peptide(s), thereby biasing Rev's trafficking into the nucleus. Combined imaging and functional assays also indicated that NES masking underpins Rev's well-known tendency to accumulate at the nucleolus, as well as Rev's capacity to activate optimal levels of late viral gene expression. We propose that Rev multimerization and NES masking regulates Rev's trafficking to and retention within the nucleus even prior to RNA binding. IMPORTANCE HIV-1 infects more than 34 million people worldwide causing >1 million deaths per year. Infectious virion production is activated by the essential viral Rev protein that mediates nuclear export of intron-bearing late-stage viral mRNAs. Rev's shuttling into and out of the nucleus is regulated by the antagonistic activities of both a peptide-encoded N-terminal nuclear localization signal and C-terminal nuclear export signal (NES). How Rev and related viral proteins balance strong import and export activities in order to achieve optimal levels of viral gene expression is incompletely understood. We provide evidence that multimerization provides a mechanism by which Rev transiently masks its NES peptide, thereby biasing its trafficking to and retention within the nucleus. Targeted pharmacological disruption of Rev-Rev interactions should perturb multiple Rev activities, both Rev-RNA binding and Rev's trafficking to the nucleus in the first place.

scholarly journals Recruitment of the Crm1 Nuclear Export Factor Is Sufficient To Induce Cytoplasmic Expression of Incompletely Spliced Human Immunodeficiency Virus mRNAs

2002 ◽  
Vol 76 (5) ◽  
pp. 2036-2042 ◽  
Author(s):  
Rui Yi ◽  
Hal P. Bogerd ◽  
Bryan R. Cullen
Keyword(s):  
Human Immunodeficiency Virus ◽  
Nuclear Export ◽  
Rna Binding ◽  
Regulatory Protein ◽  
Binding Domain ◽  
Viral Mrnas ◽  
Rev Response Element ◽  
Cytoplasmic Expression ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Cytoplasmic expression of the incompletely spliced RNA transcripts that encode the late, structural proteins of human immunodeficiency virus type 1 (HIV-1) is dependent on the viral Rev regulatory protein. General agreement exists that Rev acts, at least in part, by recruiting the cellular Crm1 nuclear export factor to HIV-1 transcripts bearing the Rev response element RNA target, and thereby inducing their nuclear egress. However, several groups have argued that Crm1 recruitment may not be sufficient for Rev function. Thus, several additional candidate cofactors for Rev have been proposed, and Rev has also been suggested to also inhibit the nuclear splicing of HIV-1 transcripts and/or to directly enhance their cytoplasmic translation. To examine whether Crm1 recruitment is, instead, sufficient to activate the nuclear export of viral mRNAs, we targeted a leucine-rich Crm1 binding domain, derived from a heterologous protein that normally plays no role in RNA metabolism, to HIV-1 RNAs and showed that this tethered Crm1 binding domain is sufficient to induce the nuclear export and cytoplasmic translation of late HIV-1 mRNA species. More importantly, we show that direct tethering of the Crm1 nuclear export factor to target mRNAs, by fusion to a heterologous RNA binding domain, is in and of itself sufficient to induce the nuclear export and cytoplasmic expression of the unspliced HIV-1 mRNAs that encode the viral Gag proteins.

scholarly journals Expression of Exogenous Sam68, the 68-Kilodalton Src-Associated Protein in Mitosis, Is Able To Alleviate Impaired Rev Function in Astrocytes

2002 ◽  
Vol 76 (9) ◽  
pp. 4526-4535 ◽  
Author(s):  
Jinliang Li ◽  
Ying Liu ◽  
In-Woo Park ◽  
Johnny J. He
Keyword(s):  
Gene Expression ◽  
Nuclear Export ◽  
Molecular Mechanisms ◽  
Subcellular Fractionation ◽  
Dominant Negative ◽  
Double Mutation ◽  
Gene Assay ◽  
Immunodeficiency Virus ◽  
Hiv 1

ABSTRACT Human immunodeficiency virus type 1 (HIV-1) gene expression in astrocytes is restricted, resulting in a brief and limited synthesis of HIV-1 viral structural proteins. Impaired Rev function has been documented in these cells. However, the molecular mechanisms underlying the impaired Rev function are not fully understood. Using the astroglial cell line U87.MG as a model, we report here that HIV-1 gene expression down-regulated expression of Sam68, the 68-kDa Src-associated protein in mitosis, which was constitutively expressed at a lower level in astrocytes. Elevating the endogenous level of Sam68 expression considerably restored HIV-1 Rev function in astrocytes, as determined by a Rev-dependent reporter gene assay. However, elevation of Sam68 expression achieved only a modest increase in HIV-1 production, further supporting the notion that there are multiple cellular restrictions of HIV-1 gene expression in astrocytes. Mutagenesis analysis identified the region between amino acids 321 and 410 of Sam68 as being directly involved in the binding of Sam68 to Rev, while a double mutation in Rev, L78D and E79L, like those in the dominant-negative Rev mutant M10, eliminated Rev binding to Sam68. Moreover, subcellular fractionation and digital fluorescence microscopic imaging revealed that Sam68 expression promoted Rev nuclear export. Taken together, our studies demonstrate that a lower level of constitutive Sam68 expression, followed by further down-regulation by HIV-1 infection, contributes to impaired Rev function in astrocytes, and they suggest that Sam68 may play an important role in Rev nuclear export.

scholarly journals Nucleo-cytoplasmic shuttling of splicing factor SRSF1 is required for development and cilia function

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Fiona Haward ◽  
Magdalena M Maslon ◽  
Patricia L Yeyati ◽  
Nicolas Bellora ◽  
Jan Niklas Hansen ◽  
...  
Keyword(s):  
Gene Expression ◽  
Mouse Model ◽  
Rna Splicing ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Small Body ◽  
Splicing Factor ◽  
Nuclear Retention ◽  
Ciliary Ultrastructure ◽  
Retention Signal

Shuttling RNA-binding proteins coordinate nuclear and cytoplasmic steps of gene expression. The SR family proteins regulate RNA splicing in the nucleus and a subset of them, including SRSF1, shuttles between the nucleus and cytoplasm affecting post-splicing processes. However, the physiological significance of this remains unclear. Here, we used genome editing to knock-in a nuclear retention signal (NRS) in Srsf1 to create a mouse model harboring an SRSF1 protein that is retained exclusively in the nucleus. Srsf1NRS/NRS mutants displayed small body size, hydrocephalus and immotile sperm, all traits associated with ciliary defects. We observed reduced translation of a subset of mRNAs and decreased abundance of proteins involved in multiciliogenesis, with disruption of ciliary ultrastructure and motility in cells and tissues derived from this mouse model. These results demonstrate that SRSF1 shuttling is used to reprogram gene expression networks in the context of high cellular demands, as observed here, during motile ciliogenesis.

scholarly journals Emerging Role of Circular RNA–Protein Interactions

2021 ◽  
Vol 7 (3) ◽  
pp. 48
Author(s):  
Arundhati Das ◽  
Tanvi Sinha ◽  
Sharmishtha Shyamal ◽  
Amaresh Chandra Panda
Keyword(s):  
Gene Expression ◽  
Protein Interactions ◽  
Nuclear Export ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Critical Role ◽  
Large Family ◽  
Circular Rnas ◽  
Protein Interaction Data ◽  
Cell Physiology

Circular RNAs (circRNAs) are emerging as novel regulators of gene expression in various biological processes. CircRNAs regulate gene expression by interacting with cellular regulators such as microRNAs and RNA binding proteins (RBPs) to regulate downstream gene expression. The accumulation of high-throughput RNA–protein interaction data revealed the interaction of RBPs with the coding and noncoding RNAs, including recently discovered circRNAs. RBPs are a large family of proteins known to play a critical role in gene expression by modulating RNA splicing, nuclear export, mRNA stability, localization, and translation. However, the interaction of RBPs with circRNAs and their implications on circRNA biogenesis and function has been emerging in the last few years. Recent studies suggest that circRNA interaction with target proteins modulates the interaction of the protein with downstream target mRNAs or proteins. This review outlines the emerging mechanisms of circRNA–protein interactions and their functional role in cell physiology.

Regulation of HIV-1 Gene Expression by the RNA-Binding Proteins tat and rev

1991 ◽  
pp. 194-218 ◽  
Author(s):  
J. Karn ◽  
C. Dingwall ◽  
M. J. Gait ◽  
S. Heaphy ◽  
M. A. Skinner
Keyword(s):  
Gene Expression ◽  
Binding Proteins ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Hiv 1
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