Molecular basis of transcriptional repression of anti-CRISPR by anti-CRISPR-associated 2

2022 ◽  
Vol 78 (1) ◽  
Author(s):  
So Yeon Lee ◽  
Gi Eob Kim ◽  
Hyun Ho Park
Keyword(s):  
Host Defense ◽  
Transcriptional Repression ◽  
Defense Mechanisms ◽  
Transcriptional Control ◽  
Immune Escape ◽  
Working Mechanism ◽  
Upstream Promoter ◽  
Fine Regulation ◽  
Immune Escape Mechanisms

CRISPR–Cas systems are well known host defense mechanisms that are conserved in bacteria and archaea. To counteract CRISPR–Cas systems, phages and viruses have evolved to possess multiple anti-CRISPR (Acr) proteins that can inhibit the host CRISPR–Cas system via different strategies. The expression of acr genes is controlled by anti-CRISPR-associated (Aca) proteins that bind to an upstream promoter and regulate the expression of acr genes during transcription. Although the role of Aca as a transcriptional repressor has been demonstrated, the mechanism of action of Aca has not been determined. Here, the molecular mechanism underlying the Aca2-mediated transcriptional control of acr genes was elucidated by determining the crystal structure of Aca2 from Oceanimonas smirnovii at a high resolution of 1.92 Å. Aca2 forms a dimer in solution, and dimerization of Aca2 is critical for specific promoter binding. The promoter-binding strategy of dimeric Aca2 was also revealed by performing mutagenesis studies. The atomic structure of the Aca family shown in this study provides insights into the fine regulation of host defense and immune-escape mechanisms and also demonstrates the conserved working mechanism of the Aca family.

scholarly journals Role of Intestinal Mucins in Innate Host Defense Mechanisms against Pathogens

2008 ◽  
Vol 1 (2) ◽  
pp. 123-135 ◽  
Author(s):  
Poonam Dharmani ◽  
Vikas Srivastava ◽  
Vanessa Kissoon-Singh ◽  
Kris Chadee
Keyword(s):  
Host Defense ◽  
Defense Mechanisms ◽  
Intestinal Mucins

Sex-dependent liver colonization of human melanoma in SCID mice—role of host defense mechanisms

2012 ◽  
Vol 30 (4) ◽  
pp. 497-506 ◽  
Author(s):  
Judit Dobos ◽  
Anita Mohos ◽  
József Tóvári ◽  
Erzsébet Rásó ◽  
Tamás Lőrincz ◽  
...  
Keyword(s):  
Host Defense ◽  
Defense Mechanisms ◽  
Human Melanoma ◽  
Scid Mice

scholarly journals Interaction of the Srb10 Kinase with Sip4, a Transcriptional Activator of Gluconeogenic Genes in Saccharomyces cerevisiae

2001 ◽  
Vol 21 (17) ◽  
pp. 5790-5796 ◽  
Author(s):  
Olivier Vincent ◽  
Sergei Kuchin ◽  
Seung-Pyo Hong ◽  
Robert Townley ◽  
Valmik K. Vyas ◽  
...  
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Rna Polymerase Ii ◽  
Transcriptional Repression ◽  
Transcriptional Control ◽  
Carbon Sources ◽  
Transcriptional Activator ◽  
Glucose Limitation ◽  
Cell Extracts ◽  
Rna Polymerase Ii Holoenzyme

ABSTRACT Sip4 is a Zn2Cys6 transcriptional activator that binds to the carbon source-responsive elements of gluconeogenic genes in Saccharomyces cerevisiae. The Snf1 protein kinase interacts with Sip4 and regulates its phosphorylation and activator function in response to glucose limitation; however, evidence suggested that another kinase also regulates Sip4. Here we examine the role of the Srb10 kinase, a component of the RNA polymerase II holoenzyme that has been primarily implicated in transcriptional repression but also positively regulates Gal4. We show that Srb10 is required for phosphorylation of Sip4 during growth in nonfermentable carbon sources and that the catalytic activity of Srb10 stimulates the ability of LexA-Sip4 to activate transcription of a reporter. Srb10 and Sip4 coimmunoprecipitate from cell extracts and interact in two-hybrid assays, suggesting that Srb10 regulates Sip4 directly. We also present evidence that the Srb10 and Snf1 kinases interact with different regions of Sip4. These findings support the view that the Srb10 kinase not only plays negative roles in transcriptional control but also has broad positive roles during growth in carbon sources other than glucose.

scholarly journals Proteomic approaches to understanding the role of the cytoskeleton in host-defense mechanisms

2011 ◽  
Vol 8 (1) ◽  
pp. 117-126 ◽  
Author(s):  
Marko Radulovic ◽  
Jasminka Godovac-Zimmermann
Keyword(s):  
Host Defense ◽  
Defense Mechanisms

scholarly journals Interleukin-23 (IL-23)-IL-17 Cytokine Axis in Murine Pneumocystis carinii Infection

2007 ◽  
Vol 75 (6) ◽  
pp. 3055-3061 ◽  
Author(s):  
Xiaowen L. Rudner ◽  
Kyle I. Happel ◽  
Erana A. Young ◽  
Judd E. Shellito
Keyword(s):  
T Cells ◽  
Host Defense ◽  
Defense Mechanisms ◽  
Pneumocystis Carinii ◽  
Neutralizing Antibody ◽  
Wild Type ◽  
Pneumocystis Carinii Infection ◽  
Interleukin 23

ABSTRACT Host defense mechanisms against Pneumocystis carinii are not fully understood. Previous work in the murine model has shown that host defense against infection is critically dependent upon host CD4+ T cells. The recently described Th17 immune response is predominantly a function of effector CD4+ T cells stimulated by interleukin-23 (IL-23), but whether these cells are required for defense against P. carinii infection is unknown. We tested the hypothesis that P. carinii stimulates the early release of IL-23, leading to increases in IL-17 production and lung effector CD4+ T-cell population that mediate clearance of infection. In vitro, stimulation of alveolar macrophages with P. carinii induced IL-23, and IL-23p19 mRNA was expressed in lungs of mice infected with this pathogen. To address the role of IL-23 in resistance to P. carinii, IL-23p19−/− and wild-type control C57BL/6 mice were infected and their fungal burdens and cytokine/chemokine responses were compared. IL-23p19−/− mice displayed transient but impaired clearance of infection, which was most apparent 2 weeks after inoculation. In confirmatory studies, the administration of either anti-IL-23p19 or anti-IL-17 neutralizing antibody to wild-type mice infected with P. carinii also caused increases in fungal burdens. IL-17 and the lymphocyte chemokines IP-10, MIG, MIP-1α, MIP-1β, and RANTES were decreased in the lungs of infected IL-23p19−/− mice in comparison to their levels in the lungs of wild-type mice. In IL-23p19−/− mice infected with P. carinii, there were fewer effector CD4+ T cells in the lung tissue. Collectively, these studies indicate that the IL-23-IL-17 axis participates in host defense against P. carinii.

scholarly journals Immuno-genomic PanCancer Landscape Reveals Diverse Immune Escape Mechanisms and Immuno-Editing Histories

2018 ◽  
Author(s):  
Shinichi Mizuno ◽  
Rui Yamaguchi ◽  
Takanori Hasegawa ◽  
Shuto Hayashi ◽  
Masashi Fujita ◽  
...  
Keyword(s):  
Immune Escape ◽  
Cancer Hallmarks ◽  
Whole Genomes ◽  
Immune Therapies ◽  
History Of ◽  
Copy Number Changes ◽  
Immune Related Genes ◽  
Tumor Types ◽  
Immune Escape Mechanisms

AbstractImmune reactions in the tumor micro-environment are one of the cancer hallmarks and emerging immune therapies have been proven effective in many types of cancer. To investigate cancer genome-immune interactions and the role of immuno-editing or immune escape mechanisms in cancer development, we analyzed 2,834 whole genomes and RNA-seq datasets across 31 distinct tumor types from the PanCancer Analysis of Whole Genomes (PCAWG) project with respect to key immuno-genomic aspects. We show that selective copy number changes in immune-related genes could contribute to immune escape. Furthermore, we developed an index of the immuno-editing history of each tumor sample based on the information of mutations in exonic regions and pseudogenes. Our immuno-genomic analyses of pan-cancer analyses have the potential to identify a subset of tumors with immunogenicity and diverse background or intrinsic pathways associated with their immune status and immuno-editing history.

scholarly journals Role of Specialized Pro-Resolving Mediators in Modifying Host Defense and Decreasing Bacterial Virulence

Molecules ◽  
2021 ◽  
Vol 26 (22) ◽  
pp. 6970
Author(s):  
Julianne M. Thornton ◽  
Kingsley Yin
Keyword(s):  
Host Defense ◽  
Host Response ◽  
Tissue Repair ◽  
Defense Mechanisms ◽  
Neutrophil Migration ◽  
Bacterial Virulence ◽  
Innate Immune ◽  
Bioactive Fatty Acids ◽  
Insight Into

Bacterial infection activates the innate immune system as part of the host’s defense against invading pathogens. Host response to bacterial pathogens includes leukocyte activation, inflammatory mediator release, phagocytosis, and killing of bacteria. An appropriate host response requires resolution. The resolution phase involves attenuation of neutrophil migration, neutrophil apoptosis, macrophage recruitment, increased phagocytosis, efferocytosis of apoptotic neutrophils, and tissue repair. Specialized Pro-resolving Mediators (SPMs) are bioactive fatty acids that were shown to be highly effective in promoting resolution of infectious inflammation and survival in several models of infection. In this review, we provide insight into the role of SPMs in active host defense mechanisms for bacterial clearance including a new mechanism of action in which an SPM acts directly to reduce bacterial virulence.

scholarly journals The role of tumor-derived exosomes in tumor immune escape: A concise review

2020 ◽  
Vol 7 (11) ◽  
pp. 4132-4137
Author(s):  
Nhat Chau Truong ◽  
Thao Nhi Huynh ◽  
Khuong Duy Pham ◽  
Phuc Van Pham
Keyword(s):  
Immune Modulation ◽  
Immune Escape ◽  
Suppressor Cells ◽  
Target Cells ◽  
Myeloid Derived Suppressor Cells ◽  
Tumor Immune Escape ◽  
Concise Review ◽  
Viable Cells ◽  
Immune Escape Mechanisms

Exosomes are small vesicles secreted by viable cells into the microenvironment. These vesicles bring various compositions, including lipids, RNAs and proteins, which carry information from producer cells to target cells. Cancer cells also produce exosomes, termed as tumor-derived exosomes (TDEs), which play important roles in immune modulation, angiogenesis and metastasis of tumors. This review summarizes the roles of TDEs in tumor immune escape mechanisms. TDEs affect all kinds of tumor-associated immune cells, including natural killer (NK) cells, dendritic cells (DCs), T and B lymphocytes, and myeloid-derived suppressor cells (MDSCs). Generally, TDEs suppress the immune system to promote tumor immune escape, thereby significantly contributing to tumorigenesis and metastasis.

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