Toxoplasma gondii ROP16 kinase silences the cyclin B1 gene promoter by hijacking host cell UHRF1-dependent epigenetic pathways

Progression through the somatic cell cycle requires the temporal regulation of cyclin gene expression and cyclin protein turnover. One of the best-characterized examples of this regulation is seen for the B-type cyclins. These cyclins and their catalytic component, cdc2, have been shown to mediate both the entry into and maintenance of mitosis. The cyclin B1 gene has been shown to be expressed between the late S and G2 phases of the cell cycle, while the protein is degraded specifically at interphase via ubiquitination. To understand the molecular basis for transcriptional regulation of the cyclin B1 gene, we cloned the human cyclin B1 gene promoter region. Using a chloramphenicol acetyltransferase reporter system and both stable and transient assays, we have shown that the cyclin B1 gene promoter (extending to -3800 bp relative to the cap site) can confer G2-enhanced promoter activity. Further analysis revealed that an upstream stimulatory factor (USF)-binding site and its cognate transcription factor(s) are critical for expression from the cyclin B1 promoter in cycling HeLa cells. Interestingly, USF DNA-binding activity appears to be regulated in a G2-specific fashion, supporting the idea that USF may play some role in cyclin B1 gene activation. These studies suggest an important link between USF and the cyclin B1 gene, which in part explains how maturation promoting factor complex formation is regulated.

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Minute Virus of Mice Inhibits Transcription of the Cyclin B1 Gene during Infection

Journal of Virology ◽

10.1128/jvi.00428-17 ◽

2017 ◽

Vol 91 (14) ◽

Cited By ~ 6

Author(s):

Matthew S. Fuller ◽

Kinjal Majumder ◽

David J. Pintel

Keyword(s):

Rna Polymerase Ii ◽

Gene Promoter ◽

Cyclin B1 ◽

Minute Virus Of Mice ◽

B1 Gene ◽

Damage Response ◽

Infected Cells ◽

Minute Virus ◽

Nuclear Environment ◽

Cellular Dna

ABSTRACT Replication of minute virus of mice (MVM) induces a sustained cellular DNA damage response (DDR) which the virus then exploits to prepare the nuclear environment for effective parvovirus takeover. An essential aspect of the MVM-induced DDR is the establishment of a potent premitotic block, which we previously found to be independent of activated p21 and ATR/Chk1 signaling. This arrest, unlike others reported previously, depends upon a significant, specific depletion of cyclin B1 and its encoding RNA, which precludes cyclin B1/CDK1 complex function, thus preventing mitotic entry. We show here that while the stability of cyclin B1 RNA was not affected by MVM infection, the production of nascent cyclin B1 RNA was substantially diminished at late times postinfection. Ectopic expression of NS1 alone did not reduce cyclin B1 expression. MVM infection also reduced the levels of cyclin B1 protein, and RNA levels normally increased in response to DNA-damaging reagents. We demonstrated that at times of reduced cyclin B1 expression during infection, there was a significantly reduced occupancy of RNA polymerase II and the essential mitotic transcription factor FoxM1 on the cyclin B1 gene promoter. Additionally, while total FoxM1 levels remained constant, there was a significant decrease of the phosphorylated, likely active, forms of FoxM1. Targeting of a constitutively active FoxM1 construct or the activation domain of FoxM1 to the cyclin B1 gene promoter via clustered regularly interspaced short palindromic repeats (CRISPR)-enzymatically inactive Cas9 in MVM-infected cells increased both cyclin B1 protein and RNA levels, implicating FoxM1 as a critical target for cyclin B1 inhibition during MVM infection. IMPORTANCE Replication of the parvovirus minute virus of mice (MVM) induces a sustained cellular DNA damage response (DDR) which the virus exploits to prepare the nuclear environment for effective takeover. An essential aspect of the MVM-induced DDR is establishment of a potent premitotic block. This block depends upon a significant, specific depletion of cyclin B1 and its encoding RNA that precludes cyclin B1/CDK1 complex functions necessary for mitotic entry. We show that reduced cyclin B1 expression is controlled primarily at the level of transcription initiation. Additionally, the essential mitotic transcription factor FoxM1 and RNA polymerase II were found to occupy the cyclin B1 gene promoter at reduced levels during infection. Recruiting a constitutively active FoxM1 construct or the activation domain of FoxM1 to the cyclin B1 gene promoter via CRISPR-catalytically inactive Cas9 (dCas9) in MVM-infected cells increased expression of both cyclin B1 protein and RNA, implicating FoxM1 as a critical target mediating MVM-induced cyclin B1 inhibition.

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Molecular Studies on Toxoplasma Gondii in Sheep and Goats in Ismailia Province, Egypt

Archives of Infectious Diseases & Therapy ◽

10.33140/aidt/02/02/00003 ◽

2018 ◽

Vol 2 (2) ◽

Keyword(s):

Toxoplasma Gondii ◽

Host Cell ◽

Nested Pcr ◽

Histopathological Examination ◽

Post Inoculation ◽

Cell Cytoplasm ◽

Host Cell Cytoplasm ◽

B1 Gene ◽

Molecular Studies ◽

Pcr Techniques

Diagnosis of Toxoplasma gondii in 20 brain samples (10 from sheep and 10 from goats) using nested PCR techniques by amplification of the T. gondii B1 gene revealed that, six sheep’s brain samples were positive (60%) and six goat’s brain samples were positive (60%). Bioassay was done by inoculation of T. gondii positive PCR samples into healthy mice. Histopathological examination of the experimental mice brains, declared pathological lesions with demonstration of pseudocysts containing bradizoites within the host cell cytoplasm in the mice killed 30th day and 35th day post inoculation.

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Faculty Opinions recommendation of The IL-12 Response of Primary Human Dendritic Cells and Monocytes to Toxoplasma gondii Is Stimulated by Phagocytosis of Live Parasites Rather Than Host Cell Invasion.

Faculty Opinions – Post-Publication Peer Review of the Biomedical Literature ◽

10.3410/f.725957291.793518980 ◽

2016 ◽

Author(s):

Frank Seeber

Keyword(s):

Dendritic Cells ◽

Toxoplasma Gondii ◽

Host Cell ◽

Cell Invasion ◽

Host Cell Invasion ◽

Human Dendritic Cells

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Toxoplasma gondii manipulates host cell signaling pathways via its secreted effector molecules

Parasitology International ◽

10.1016/j.parint.2021.102368 ◽

2021 ◽

Vol 83 ◽

pp. 102368

Author(s):

Fumiaki Ihara ◽

Yoshifumi Nishikawa

Keyword(s):

Toxoplasma Gondii ◽

Cell Signaling ◽

Host Cell ◽

Signaling Pathways ◽

Effector Molecules ◽

Host Cell Signaling ◽

Cell Signaling Pathways

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1,3,4-Thiadiazoles Effectively Inhibit Proliferation of Toxoplasma gondii

Cells ◽

10.3390/cells10051053 ◽

2021 ◽

Vol 10 (5) ◽

pp. 1053

Author(s):

Lidia Węglińska ◽

Adrian Bekier ◽

Katarzyna Dzitko ◽

Barbara Pacholczyk-Sienicka ◽

Łukasz Albrecht ◽

...

Keyword(s):

Toxoplasma Gondii ◽

Host Cell ◽

Cell Invasion ◽

Direct Action ◽

Human Fibroblasts ◽

Imidazole Ring ◽

Host Cells ◽

In Vitro Assays ◽

Host Cell Invasion

Congenital and acquired toxoplasmosis caused by the food- and water-born parasite Toxoplasma gondii (T. gondii) is one of the most prevalent zoonotic infection of global importance. T. gondii is an obligate intracellular parasite with limited capacity for extracellular survival, thus a successful, efficient and robust host cell invasion process is crucial for its survival, proliferation and transmission. In this study, we screened a series of novel 1,3,4-thiadiazole-2-halophenylamines functionalized at the C5 position with the imidazole ring (1b–12b) for their effects on T. gondii host cell invasion and proliferation. To achieve this goal, these compounds were initially subjected to in vitro assays to assess their cytotoxicity on human fibroblasts and then antiparasitic efficacy. Results showed that all of them compare favorably to control drugs sulfadiazine and trimethoprim in terms of T. gondii growth inhibition (IC50) and selectivity toward the parasite, expressed as selectivity index (SI). Subsequently, the most potent of them with meta-fluoro 2b, meta-chloro 5b, meta-bromo 8b, meta-iodo 11b and para-iodo 12b substitution were tested for their efficacy in inhibition of tachyzoites invasion and subsequent proliferation by direct action on established intracellular infection. All the compounds significantly inhibited the parasite invasion and intracellular proliferation via direct action on both tachyzoites and parasitophorous vacuoles formation. The most effective was para-iodo derivative 12b that caused reduction in the percentage of infected host cells by 44% and number of tachyzoites per vacuole by 93% compared to non-treated host cells. Collectively, these studies indicate that 1,3,4-thiadiazoles 1b–12b, especially 12b with IC50 of 4.70 µg/mL and SI of 20.89, could be considered as early hit compounds for future design and synthesis of anti-Toxoplasma agents that effectively and selectively block the invasion and subsequent proliferation of T. gondii into host cells.

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