Interference on Cytosolic DNA Activation Attenuates Sepsis Severity: Experiments on Cyclic GMP-AMP Synthase (cGAS) Deficient Mice

  • Although the enhanced responses against serum cell-free DNA (cfDNA) in cases of sepsis-a life-threatening organ dysfunction due to systemic infection-are understood, the influence of the cytosolic DNA receptor cGAS (cyclic guanosine monophosphate-adenosine monophosphate (GMP-AMP) synthase) on sepsis is still unclear. Here, experiments on cGAS deficient (cGAS-/-) mice were conducted using cecal ligation and puncture (CLP) and lipopolysaccharide (LPS) injection sepsis models and macrophages. Severity of CLP in cGAS-/- mice was less severe than in wildtype (WT) mice, as indicated by mortality, serum LPS, cfDNA, leukopenia, cytokines (TNF-α, IL-6 and IL-10), organ histology (lung, liver and kidney) and spleen apoptosis.
  • With the LPS injection model, serum cytokines in cGAS-/- mice were lower than in WT mice, despite the similar serum cfDNA level. Likewise, in LPS-activated WT macrophages, the expression of several mitochondria-associated genes (as revealed by RNA sequencing analysis) and a profound reduction in mitochondrial parameters, including maximal respiration (determined by extracellular flux analysis), DNA (mtDNA) and mitochondrial abundance (revealed by fluorescent staining), were demonstrated. These data implied the impact of cfDNA resulting from LPS-induced cell injury.
  • In parallel, an additive effect of bacterial DNA on LPS, seen in comparison with LPS alone, was demonstrated in WT macrophages, but not in cGAS-/- cells, as indicated by supernatant cytokines (TNF-α and IL-6), M1 proinflammatory polarization (iNOS and IL-1β), cGAS, IFN-γ and supernatant cyclic GMP-AMP (cGAMP). In conclusion, cGAS activation by cfDNA from hosts (especially mtDNA) and bacteria was found to induce an additive proinflammatory effect on LPS-activated macrophages which was perhaps responsible for the more pronounced sepsis hyperinflammation observed in WT mice compared with the cGAS-/- group.

CdgC, a Cyclic-di-GMP Diguanylate Cyclase of Azospirillum baldaniorum Is Involved in Internalization to Wheat Roots

Azospirillum baldaniorum is a plant growth-promoting rhizobacterium (PGPR) capable of fixing nitrogen, the synthesis of several phytohormones including indole-acetic acid, and induction of plant defenses against phytopathogens. To establish a successful and prolonged bacteria-plant interaction, A. baldaniorum can form biofilms, bacterial communities embedded in a self-made matrix formed by extracellular polymeric substances which provide favorable conditions for survival. A key modulator of biofilm formation is the second messenger bis-(3′-5′)-cyclic-dimeric-GMP (c-di-GMP), which is synthesized by diguanylate cyclases (DGC) and degraded by specific phosphodiesterases. In this study, we analyzed the contribution of a previously uncharacterized diguanylate cyclase designated CdgC, to biofilm formation and bacterial-plant interaction dynamics. We showed that CdgC is capable of altering c-di-GMP levels in a heterologous host, strongly supporting its function as a DGC.
The deletion of cdgC resulted in alterations in the three-dimensional structure of biofilms in a nitrogen-source dependent manner. CdgC was required for optimal colonization of wheat roots. Since we also observed that CdgC played an important role in exopolysaccharide production, we propose that this signaling protein activates a physiological response that results in the strong attachment of bacteria to the roots, ultimately contributing to an optimal bacterium-plant interaction. Our results demonstrate that the ubiquitous second messenger c-di-GMP is a key factor in promoting plant colonization by the PGPR A. baldaniorum by allowing proficient internalization in wheat roots. Understanding the molecular basis of PGPR-plant interactions will enable the design of better biotechnological strategies of agro-industrial interest.

The role of Cyclic GMP-AMP synthase and Interferon-I-inducible protein 16 as candidate biomarkers of systemic lupus erythematosus

Background: Diverse clinical and serological manifestations of systemic lupus erythematosus (SLE) compromise its diagnosis and treatment. A more reliable biomarker for SLE, which can play a critical role in either diagnosis, monitoring the disease progress or evaluating the response to treatment for individualized therapeutic, is necessary. DNA sensor is an important mediator of inflammation in systemic autoimmune diseases. However, the potential role for DNA sensor as disease activity biomarkers for SLE remained obscure. We detected the aberrant activation of DNA sensors and the corresponding IFN-β response in SLE patients, and to evaluate their potential role as disease biomarkers for SLE.
Methods: We quantified the expressions of IFN-I and DNA sensor, such as cGAS, IFI16, DDX41, DAI and their down-stream adaptor STING in PBMC derived from patients with SLE (n=100), healthy controls (HCs) (n=62) by real-time PCR. The relationships between the expression of cGAS or IFI16 and clinical features in SLE patients were investigated. ROC curve analysis was performed to examine the predictive value of cGAS and IFI16 in SLE diagnosis, disease activity monitoring, specific organ manifestation and therapeutic response. RNA interference-mediated depletion of IFI16 or cGAS was conducted to evaluate their impact on IFN-I response.
Results: The expressions of cGAS and IFI16 were significantly higher in PBMC from SLE patients, closely correlated with the SLEDAI scores and high anti-dsDNA antibody titers. While the AUC for cGAS (0.767) was less than that of IFI16 and IFN-β, the AUC for IFI16 (0.856) and IFN-β (0.856) were similar. Expression of cGAS and IFI16 combine with IFN-β in PBMC showed high sensitivity (89.2%) and specificity (89.1%) for discrimination between mild and moderate/severe disease activity in SLE. Higher expression of IFI16 was association with ocular disorder in SLE patients. Neither IFI16 nor cGAS was a reliable indicator of therapeutic response. RNA interference-mediated depletion of IFI16 or cGAS prevented active SLE serum-induced upregulating in both IFN-α and IFN-β.
Conclusions: High expression levels of cGAS and IFI16 in PBMC from SLE patients correlated strongly with disease activity. Both cGAS and IFI16 mediated signaling pathway were account for the robust production of IFN-β. Expression of cGAS and IFI16 combined with IFN-β in PBMC might serve as potential biomarkers for early diagnosis and monitoring disease activity in SLE.

cGMP (cyclic GMP)

MBS6507358-005mL MyBiosource 0.05mL 835 EUR

cGMP (cyclic GMP)

MBS6507358-5x005mL MyBiosource 5x0.05mL 3600 EUR

Cyclic GMP (TBAOH)

HY-113469B MedChemExpress 10 mg 70.35 EUR

Cyclic GMP (sodium)

HY-113469A MedChemExpress 10 mg 70.35 EUR

Cyclic GMP Antibody

abx022640-02ml Abbexa 0.2 ml 1128 EUR

Cyclic GMP Antibody

GWB-BA5CC2 GenWay Biotech 0.2 ml Ask for price

Cyclic GMP Antibody

GWB-DFA25F GenWay Biotech 2 ml Ask for price

Cyclic GMP EIA Kit

SKT-211-96 Stressmarq 1 plate of 96 wells 568.8 EUR


MBS222513-2mL MyBiosource 2mL 455 EUR


MBS222513-5x2mL MyBiosource 5x2mL 1870 EUR

Sheep anti Cyclic GMP

MBS316214-02mL MyBiosource 0.2mL 1235 EUR

Sheep anti Cyclic GMP

MBS316214-5x02mL MyBiosource 5x0.2mL 5380 EUR

Cyclic GMP (Direct) ELISA

MBS494508-5x96Tests MyBiosource 5x96Tests 3410 EUR

Cyclic GMP (Direct) ELISA

MBS494508-96Tests MyBiosource 96Tests 740 EUR

Cyclic GMP Standard, 125UL

C080-125UL Arbor Assays 125UL 85 EUR

Cyclic GMP Standard, 350UL

C080-350UL Arbor Assays 350UL 207 EUR

Cyclic GMP Standard, 625UL

C080-625UL Arbor Assays 625UL 207 EUR

Cyclic GMP Standard, 70UL

C080-70UL Arbor Assays 70UL 85 EUR

Anti- Cyclic GMP Antibody

GWB-FDE020 GenWay Biotech 1000 TESTS Ask for price

Cyclic GMP Polyclonal Antibody

MBS194212-02mL MyBiosource 0.2mL 560 EUR

Cyclic GMP Polyclonal Antibody

MBS194212-5x02mL MyBiosource 5x0.2mL 2510 EUR


MBS2516175-10x96Tests MyBiosource 10x96Tests 3265 EUR


MBS2516175-24Tests MyBiosource 24Tests 225 EUR


MBS2516175-48Test MyBiosource 48Test 350 EUR


MBS2516175-5x96Test MyBiosource 5x96Test 1655 EUR


MBS2516175-96Tests MyBiosource 96Tests 395 EUR

ELISA kit for cGMP (Cyclic GMP)

E-EL-0083 Elabscience Biotech 1 plate of 96 wells 452.4 EUR

DetectX® Cyclic GMP Antibody, 3ML

C078-3ML Arbor Assays 3ML 218 EUR

Downregulation of mitochondrial biogenesis by virus infection triggers antiviral responses by cyclic GMP-AMP synthase

In general, in mammalian cells, cytosolic DNA viruses are sensed by cyclic GMP-AMP synthase (cGAS), and RNA viruses are recognized by retinoic acid-inducible gene I (RIG-I)-like receptors, triggering a series of downstream innate antiviral signaling steps in the host. We previously reported that measles virus (MeV), which possesses an RNA genome, induces rapid antiviral responses, followed by comprehensive downregulation of host gene expression in epithelial cells. Interestingly, gene ontology analysis indicated that genes encoding mitochondrial proteins are enriched among the list of downregulated genes. To evaluate mitochondrial stress after MeV infection, we first observed the mitochondrial morphology of infected cells and found that significantly elongated mitochondrial networks with a hyperfused phenotype were formed.
In addition, an increased amount of mitochondrial DNA (mtDNA) in the cytosol was detected during progression of infection. Based on these results, we show that cytosolic mtDNA released from hyperfused mitochondria during MeV infection is captured by cGAS and causes consequent priming of the DNA sensing pathway in addition to canonical RNA sensing. We also ascertained the contribution of cGAS to the in vivo pathogenicity of MeV. In addition, we found that other viruses that induce downregulation of mitochondrial biogenesis as seen for MeV cause similar mitochondrial hyperfusion and cytosolic mtDNA-priming antiviral responses. These findings indicate that the mtDNA-activated cGAS pathway is critical for full innate control of certain viruses, including RNA viruses that cause mitochondrial stress.

Leave a Reply

Your email address will not be published.