Cell cycle G2 arrest induced by HIV-1 Vpr in fission yeast (Schizosaccharomyces pombe) is independent of cell death and early genes in the DNA damage checkpoint

ABSTRACT Mitotic checkpoints restrain the onset of mitosis (M) when DNA is incompletely replicated or damaged. These checkpoints are conserved between the fission yeast Schizosaccharomyces pombe and mammals. In both types of organisms, the methylxanthine caffeine overrides the synthesis (S)-M checkpoint that couples mitosis to completion of DNA S phase. The molecular target of caffeine was sought in fission yeast. Caffeine prevented activation of Cds1 and phosphorylation of Chk1, two protein kinases that enforce the S-M checkpoint triggered by hydroxyurea. Caffeine did not inhibit these kinases in vitro but did inhibit Rad3, a kinase that regulates Cds1 and Chk1. In accordance with this finding, caffeine also overrode the G2-M DNA damage checkpoint that requires Rad3 function. Rad3 coprecipitated with Cds1 expressed at endogenous amounts, a finding that supports the hypothesis that Rad3 is involved in direct activation of Cds1.

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Huntingtin-interacting Protein 1 Promotes Vpr-induced G2 Arrest and HIV-1 Infection in Macrophages

10.21203/rs.3.rs-76686/v1 ◽

2020 ◽

Author(s):

Tomoyuki Murakami ◽

Nopporn Chutiwitoonchai ◽

Masami Takei ◽

Yoko Aida

Keyword(s):

Cell Cycle ◽

Dna Damage ◽

Dna Double Strand Breaks ◽

G2 Arrest ◽

Interacting Protein ◽

G2 Phase ◽

Huntingtin Interacting Protein 1 ◽

Interfering Rna ◽

Huntingtin Interacting Protein ◽

Hiv 1

Abstract Background: Human immunodeficiency virus type 1 (HIV-1) modulates the host cell cycle. The HIV-1 accessory protein Vpr arrests the cell cycle at G2 phase, which is important for efficient viral replication in dividing CD4+ T cells, because the transcriptional activity of the HIV-1 long terminal repeat is most active in G2 phase. Additionally, Vpr-mediated G2 arrest likely correlates with enhanced HIV-1 infection in monocyte-derived macrophages.Results: Here, we screened small-interfering RNA to reveal candidates that suppress Vpr-induced G2 arrest and identified Huntingtin-interacting protein 1 (HIP1) as both directly interacting with Vpr and required for efficient G2 arrest. Interestingly, HIP1 was not essential for Vpr-induced DNA double-strand breaks, which are required for activation of the DNA-damage checkpoint and G2 arrest. Furthermore, HIP1 knockdown suppressed HIV-1 infection in monocyte-derived macrophages.Conclusions: These results suggest that HIP1 operates in the downstream step(s) of DNA-damage induction to promote Vpr-induced G2 arrest and enhances HIV-1 infection in macrophages.

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Monitoring Schizosaccharomyces pombe genome stress by visualizing end-binding protein Ku

Biology Open ◽

10.1242/bio.054346 ◽

2021 ◽

Vol 10 (2) ◽

Author(s):

Chance E. Jones ◽

Susan L. Forsburg

Keyword(s):

Dna Damage ◽

Schizosaccharomyces Pombe ◽

Fission Yeast ◽

Protein Complex ◽

Genome Stability ◽

Binding Protein ◽

Dna Lesions ◽

Live Cells ◽

Dna Damage Checkpoint ◽

Ku Protein

ABSTRACT Studies of genome stability have exploited visualization of fluorescently tagged proteins in live cells to characterize DNA damage, checkpoint, and repair responses. In this report, we describe a new tool for fission yeast, a tagged version of the end-binding protein Pku70 which is part of the KU protein complex. We compare Pku70 localization to other markers upon treatment to various genotoxins, and identify a unique pattern of distribution. Pku70 provides a new tool to define and characterize DNA lesions and the repair response.

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Differential effects of caffeine on DNA damage and replication cell cycle checkpoints in the fission yeast Schizosaccharomyces pombe

MGG Molecular & General Genetics ◽

10.1007/s004380050901 ◽

1998 ◽

Vol 260 (4) ◽

pp. 319-334 ◽

Cited By ~ 9

Author(s):

Fekret Osman ◽

Shirley McCready

Keyword(s):

Cell Cycle ◽

Dna Damage ◽

Schizosaccharomyces Pombe ◽

Fission Yeast ◽

Cell Cycle Checkpoints ◽

Differential Effects

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Roles of the Mitotic Inhibitors Wee1 and Mik1 in the G2 DNA Damage and Replication Checkpoints

Molecular and Cellular Biology ◽

10.1128/mcb.21.5.1499-1508.2001 ◽

2001 ◽

Vol 21 (5) ◽

pp. 1499-1508 ◽

Cited By ~ 53

Author(s):

Nicholas Rhind ◽

Paul Russell

Keyword(s):

Dna Damage ◽

Dna Replication ◽

Schizosaccharomyces Pombe ◽

Fission Yeast ◽

Dna Damage Checkpoint ◽

Mitotic Inhibitors

ABSTRACT The G2 DNA damage and DNA replication checkpoints in many organisms act through the inhibitory phosphorylation of Cdc2 on tyrosine-15. This phosphorylation is catalyzed by the Wee1/Mik1 family of kinases. However, the in vivo role of these kinases in checkpoint regulation has been unclear. We show that, in the fission yeastSchizosaccharomyces pombe, Mik1 is a target of both checkpoints and that the regulation of Mik1 is, on its own, sufficient to delay mitosis in response to the checkpoints. Mik1 appears to have two roles in the DNA damage checkpoint; one in the establishment of the checkpoint and another in its maintenance. In contrast, Wee1 does not appear to be involved in the establishment of either checkpoint.

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SOG1 transcription factor promotes the onset of endoreduplication under salinity stress in Arabidopsis

Scientific Reports ◽

10.1038/s41598-021-91293-1 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Kalyan Mahapatra ◽

Sujit Roy

Keyword(s):

Cell Cycle ◽

Dna Damage ◽

Cell Death ◽

Transcription Factor ◽

Programmed Cell Death ◽

Salinity Stress ◽

Crucial Role ◽

Genome Stability ◽

Cell Cycle Checkpoint ◽

Cell Cycle Regulators

AbstractAs like in mammalian system, the DNA damage responsive cell cycle checkpoint functions play crucial role for maintenance of genome stability in plants through repairing of damages in DNA and induction of programmed cell death or endoreduplication by extensive regulation of progression of cell cycle. ATM and ATR (ATAXIA-TELANGIECTASIA-MUTATED and -RAD3-RELATED) function as sensor kinases and play key role in the transmission of DNA damage signals to the downstream components of cell cycle regulatory network. The plant-specific NAC domain family transcription factor SOG1 (SUPPRESSOR OF GAMMA RESPONSE 1) plays crucial role in transducing signals from both ATM and ATR in presence of double strand breaks (DSBs) in the genome and found to play crucial role in the regulation of key genes involved in cell cycle progression, DNA damage repair, endoreduplication and programmed cell death. Here we report that Arabidopsis exposed to high salinity shows generation of oxidative stress induced DSBs along with the concomitant induction of endoreduplication, displaying increased cell size and DNA ploidy level without any change in chromosome number. These responses were significantly prominent in SOG1 overexpression line than wild-type Arabidopsis, while sog1 mutant lines showed much compromised induction of endoreduplication under salinity stress. We have found that both ATM-SOG1 and ATR-SOG1 pathways are involved in the salinity mediated induction of endoreduplication. SOG1was found to promote G2-M phase arrest in Arabidopsis under salinity stress by downregulating the expression of the key cell cycle regulators, including CDKB1;1, CDKB2;1, and CYCB1;1, while upregulating the expression of WEE1 kinase, CCS52A and E2Fa, which act as important regulators for induction of endoreduplication. Our results suggest that Arabidopsis undergoes endoreduplicative cycle in response to salinity induced DSBs, showcasing an adaptive response in plants under salinity stress.

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