Serum Response Factor Regulates Immediate Early Host Gene Expression in Toxoplasma gondii-Infected Host Cells

ABSTRACT Fibroblasts lose the ability to replicate in response to growth factors and become unable to express growth-associated immediate-early genes, including c-fos and egr-1, as they become senescent. The serum response factor (SRF), a major transcriptional activator of immediate-early gene promoters, loses the ability to bind to the serum response element (SRE) and becomes hyperphosphorylated in senescent cells. We identify protein kinase C delta (PKCδ) as the kinase responsible for inactivation of SRF both in vitro and endogenously in senescent cells. This is due to a higher level of PKCδ activity as cells age, production of the PKCδ catalytic fragment, and its nuclear localization in senescent but not in low-passage-number cells. The phosphorylation of T160 of SRF by PKCδ in vitro and in vivo led to loss of SRF DNA binding activity. Both the PKCδ inhibitor rottlerin and ectopic expression of a dominant negative form of PKCδ independently restored SRE-dependent transcription and immediate-early gene expression in senescent cells. Modulation of PKCδ activity in vivo with rottlerin or bistratene A altered senescent- and young-cell morphology, respectively. These observations support the idea that the coordinate transcriptional inhibition of several growth-associated genes by PKCδ contributes to the senescent phenotype.

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Simultaneous ribosome profiling of human host cells infected with Toxoplasma gondii

10.1101/619916 ◽

2019 ◽

Author(s):

Michael J. Holmes ◽

Premal Shah ◽

Ronald C. Wek ◽

William J. Sullivan

Keyword(s):

Gene Expression ◽

Toxoplasma Gondii ◽

Host Cell ◽

Translational Control ◽

Ribosome Profiling ◽

Host Gene ◽

Host Cells ◽

Host Gene Expression ◽

Quiescent Cells ◽

Study Gene Expression

AbstractToxoplasma gondii is a ubiquitous obligate intracellular parasite that infects the nucleated cells of warm-blooded animals. From within the parasitophorous vacuole in which they reside, Toxoplasma tachyzoites secrete an arsenal of effector proteins that can reprogram host gene expression to facilitate parasite survival and replication. Gaining a better understanding of how host gene expression is altered upon infection is central for understanding parasite strategies for host invasion and for developing new parasite therapies. Here, we applied ribosome profiling coupled with mRNA measurements to concurrently study gene expression in the parasite and in host human foreskin fibroblasts. By examining the parasite transcriptome and translatome, we identified potential upstream open reading frames that may permit the stress-induced preferential translation of parasite mRNAs. We also determined that tachyzoites reduce host death-associated pathways and increase survival, proliferation, and motility in both quiescent and proliferative host cell models of infection. Additionally, proliferative cells alter their gene expression in ways consistent with massive transcriptional rewiring while quiescent cells were best characterized by re-entry into the cell cycle. We also identified a translational control regimen consistent with mTOR activation in quiescent cells, and to a lesser degree in proliferative cells. This study illustrates the utility of the method for dissection of gene expression programs simultaneously in parasite and host.ImportanceToxoplasma gondii is a single-celled parasite that has infected up to one-third of the world’s population. Significant overhauls in gene expression in both the parasite and the host cell accompany parasite invasion, and a better understanding of these changes may lead to the development of new therapeutic agents. In this study, we employed ribosome profiling to determine the changes that occur at the levels of transcription and translation in both the parasite and the infected host cell at the same time. We discovered features of Toxoplasma mRNAs that suggest a means for controlling parasite gene expression under stressful conditions. We also show that differences in host gene expression occur depending on whether they are confluent or not. Our findings demonstrate the feasibility of using ribosomal profiling to interrogate the host-parasite dynamic under a variety of conditions.

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Simultaneous Ribosome Profiling of Human Host Cells Infected with Toxoplasma gondii

mSphere ◽

10.1128/msphere.00292-19 ◽

2019 ◽

Vol 4 (3) ◽

Cited By ~ 6

Author(s):

Michael J. Holmes ◽

Premal Shah ◽

Ronald C. Wek ◽

William J. Sullivan

Keyword(s):

Gene Expression ◽

Toxoplasma Gondii ◽

Host Cell ◽

Ribosome Profiling ◽

Host Gene ◽

Host Cells ◽

Host Gene Expression ◽

Content Type ◽

Quiescent Cells ◽

Study Gene Expression

ABSTRACT Toxoplasma gondii is a ubiquitous obligate intracellular parasite that infects the nucleated cells of warm-blooded animals. From within the parasitophorous vacuole in which they reside, Toxoplasma tachyzoites secrete an arsenal of effector proteins that can reprogram host gene expression to facilitate parasite survival and replication. Gaining a better understanding of how host gene expression is altered upon infection is central for understanding parasite strategies for host invasion and for developing new parasite therapies. Here, we applied ribosome profiling coupled with mRNA measurements to concurrently study gene expression in the parasite and in host human foreskin fibroblasts. By examining the parasite transcriptome and translatome, we identified potential upstream open reading frames that may permit the stress-induced preferential translation of parasite mRNAs. We also determined that tachyzoites reduce host death-associated pathways and increase survival, proliferation, and motility in both quiescent and proliferative host cell models of infection. Additionally, proliferative cells alter their gene expression in ways that are consistent with massive transcriptional rewiring, while quiescent cells were best characterized by reentry into the cell cycle. We also identified a translational control regimen consistent with mechanistic target of rapamycin (mTOR) activation in quiescent cells and, to a lesser degree, in proliferative cells. This study illustrates the utility of the method for dissection of gene expression programs simultaneously in the parasite and host. IMPORTANCE Toxoplasma gondii is a single-celled parasite that has infected up to one-third of the world’s population. Significant overhauls in gene expression in both the parasite and the host cell accompany parasite invasion, and a better understanding of these changes may lead to the development of new therapeutic agents. In this study, we employed ribosome profiling to determine the changes that occur at the levels of transcription and translation in both the parasite and the infected host cell at the same time. We discovered features of Toxoplasma mRNAs that suggest a means for controlling parasite gene expression under stressful conditions. We also show that differences in host gene expression occur depending on whether they are confluent or not. Our findings demonstrate the feasibility of using ribosomal profiling to interrogate the host-parasite dynamic under a variety of conditions.

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Pathogenic Biohacking: Induction, Modulation and Subversion of Host Transcriptional Responses by Listeria monocytogenes

Toxins ◽

10.3390/toxins12050294 ◽

2020 ◽

Vol 12 (5) ◽

pp. 294

Author(s):

Matthew J. G. Eldridge ◽

Pascale Cossart ◽

Mélanie A. Hamon

Keyword(s):

Gene Expression ◽

Listeria Monocytogenes ◽

Virulence Factors ◽

Bacterial Pathogen ◽

Typical Feature ◽

Host Gene ◽

Host Cells ◽

Host Gene Expression ◽

Transcriptional Responses ◽

The Impact

During infection, the foodborne bacterial pathogen Listeria monocytogenes dynamically influences the gene expression profile of host cells. Infection-induced transcriptional changes are a typical feature of the host-response to bacteria and contribute to the activation of protective genes such as inflammatory cytokines. However, by using specialized virulence factors, bacterial pathogens can target signaling pathways, transcription factors, and epigenetic mechanisms to alter host gene expression, thereby reprogramming the response to infection. Therefore, the transcriptional profile that is established in the host is delicately balanced between antibacterial responses and pathogenesis, where any change in host gene expression might significantly influence the outcome of infection. In this review, we discuss the known transcriptional and epigenetic processes that are engaged during Listeria monocytogenes infection, the virulence factors that can remodel them, and the impact these processes have on the outcome of infection.

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New Role for Serum Response Factor in Postnatal Skeletal Muscle Growth and Regeneration via the Interleukin 4 and Insulin-Like Growth Factor 1 Pathways

Molecular and Cellular Biology ◽

10.1128/mcb.00138-06 ◽

2006 ◽

Vol 26 (17) ◽

pp. 6664-6674 ◽

Cited By ~ 53

Author(s):

Claude Charvet ◽

Christophe Houbron ◽

Ara Parlakian ◽

Julien Giordani ◽

Charlotte Lahoute ◽

...

Keyword(s):

Gene Expression ◽

Skeletal Muscle ◽

Growth Factor ◽

Serum Response Factor ◽

Muscle Growth ◽

Interleukin 4 ◽

Specific Gene ◽

Response Factor ◽

Insulin Like Growth Factor ◽

Serum Response

ABSTRACT Serum response factor (SRF) is a crucial transcriptional factor for muscle-specific gene expression. We investigated SRF function in adult skeletal muscles, using mice with a postmitotic myofiber-targeted disruption of the SRF gene. Mutant mice displayed severe skeletal muscle mass reductions due to a postnatal muscle growth defect resulting in highly hypotrophic adult myofibers. SRF-depleted myofibers also failed to regenerate following injury. Muscles lacking SRF had very low levels of muscle creatine kinase and skeletal alpha-actin (SKA) transcripts and displayed other alterations to the gene expression program, indicating an overall immaturity of mutant muscles. This loss of SKA expression, together with a decrease in beta-tropomyosin expression, contributed to myofiber growth defects, as suggested by the extensive sarcomere disorganization found in mutant muscles. However, we observed a downregulation of interleukin 4 (IL-4) and insulin-like growth factor 1 (IGF-1) expression in mutant myofibers which could also account for their defective growth and regeneration. Indeed, our demonstration of SRF binding to interleukin 4 and IGF-1 promoters in vivo suggests a new crucial role for SRF in pathways involved in muscle growth and regeneration.

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Alternative splicing and nonsense-mediated mRNA decay regulate gene expression of serum response factor

Gene ◽

10.1016/j.gene.2007.06.008 ◽

2007 ◽

Vol 400 (1-2) ◽

pp. 131-139 ◽

Cited By ~ 13

Author(s):

Xiaomin Zhang ◽

Gohar Azhar ◽

Chris Huang ◽

Cunqi Cui ◽

Ying Zhong ◽

...

Keyword(s):

Gene Expression ◽

Alternative Splicing ◽

Mrna Decay ◽

Serum Response Factor ◽

Response Factor ◽

Regulate Gene Expression ◽

Nonsense Mediated Mrna Decay ◽

Serum Response ◽

Regulate Gene

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Different regulatory sequences control creatine kinase-M gene expression in directly injected skeletal and cardiac muscle.

Molecular and Cellular Biology ◽

10.1128/mcb.13.2.1264 ◽

1993 ◽

Vol 13 (2) ◽

pp. 1264-1272 ◽

Cited By ~ 61

Author(s):

C K Vincent ◽

A Gualberto ◽

C V Patel ◽

K Walsh

Keyword(s):

Gene Expression ◽

Skeletal Muscle ◽

Creatine Kinase ◽

Cardiac Muscle ◽

Serum Response Factor ◽

Sequence Motif ◽

Regulatory Sequences ◽

Response Factor ◽

Specific Expression ◽

Serum Response

Regulatory sequences of the M isozyme of the creatine kinase (MCK) gene have been extensively mapped in skeletal muscle, but little is known about the sequences that control cardiac-specific expression. The promoter and enhancer sequences required for MCK gene expression were assayed by the direct injection of plasmid DNA constructs into adult rat cardiac and skeletal muscle. A 700-nucleotide fragment containing the enhancer and promoter of the rabbit MCK gene activated the expression of a downstream reporter gene in both muscle tissues. Deletion of the enhancer significantly decreased expression in skeletal muscle but had no detectable effect on expression in cardiac muscle. Further deletions revealed a CArG sequence motif at position -179 within the promoter that was essential for cardiac-specific expression. The CArG element of the MCK promoter bound to the recombinant serum response factor and YY1, transcription factors which control expression from structurally similar elements in the skeletal actin and c-fos promoters. MCK-CArG-binding activities that were similar or identical to serum response factor and YY1 were also detected in extracts from adult cardiac muscle. These data suggest that the MCK gene is controlled by different regulatory programs in adult cardiac and skeletal muscle.

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OTT-MAL Is a Deregulated Activator of Serum Response Factor-Dependent Gene Expression

Molecular and Cellular Biology ◽

10.1128/mcb.00303-08 ◽

2008 ◽

Vol 28 (20) ◽

pp. 6171-6181 ◽

Cited By ~ 25

Author(s):

Arnaud Descot ◽

Monika Rex-Haffner ◽

Geneviève Courtois ◽

Dominique Bluteau ◽

Antje Menssen ◽

...

Keyword(s):

Gene Expression ◽

Fusion Protein ◽

Serum Response Factor ◽

Mitogen Activated Protein Kinase ◽

Binding Motif ◽

Fusion Partner ◽

Response Factor ◽

Transactivation Domain ◽

Regulated Gene Expression ◽

Serum Response

ABSTRACT The OTT-MAL/RBM15-MKL1 fusion protein is the result of the recurrent translocation t(1;22) in acute megakaryocytic leukemia in infants. How it contributes to the malignancy is unknown. The 3′ fusion partner, MAL/MKL1/MRTF-A, is a transcriptional coactivator of serum response factor (SRF). MAL plays a key role in regulated gene expression depending on Rho family GTPases and G-actin. Here we demonstrate that OTT-MAL is a constitutive activator of SRF and target gene expression. This requires the SRF-binding motif and the MAL-derived transactivation domain. OTT-MAL localizes to the nucleus and is not regulated by upstream signaling. OTT-MAL deregulation reflects its independence from control by G-actin, which fails to interact with OTT-MAL in coimmunoprecipitation experiments. Regulation cannot be restored by reintroduction of the entire MAL N terminus into the fusion protein. OTT-MAL also caused a delayed induction of the MAL-independent, ternary complex factor-dependent target genes c-fos and egr-1 and the mitogen-activated protein kinase/Erk pathway. With testing in heterologous tissue culture systems, however, we observed considerable antiproliferative effects of OTT-MAL. Our data suggest that the deregulated activation of MAL-dependent and -independent promoters results in tissue-specific functions of OTT-MAL.

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