scholarly journals Mechanisms of damage prevention, signalling, and repair impact the ability of Drosophila to tolerate enteric bacterial infection

2021 ◽  
Author(s):  
Arun Prakash ◽  
Katy M. Monteith ◽  
Pedro F Vale
Keyword(s):  
Tissue Damage ◽  
Protein A ◽  
Growth Factor Receptor ◽  
Bacterial Pathogen ◽  
Substantial Effect ◽  
Negative Regulator ◽  
Peritrophic Matrix ◽  
Loss Of Function ◽  
Disease Tolerance ◽  
Insect Gut

Many insects thrive on decomposing and decaying organic matter containing a large diversity of both commensal and pathogenic microorganisms. The insect gut is therefore frequently exposed to pathogenic threats and must be able not only to detect and clear these potential infections, but also be able to repair the resulting damage to gut tissues in order to tolerate relatively high microbe loads. In contrast to the mechanisms that eliminate pathogens, we currently know less about the mechanisms of disease tolerance, and most of this knowledge stems from systemic infections. Here we investigated how well-described mechanisms that either prevent, signal, control, or repair tissue damage during infection contribute to the phenotype of disease tolerance during gut infection. We orally infected adult Drosophila melanogaster flies with the bacterial pathogen Pseudomonas entomophila in several loss-of-function mutants lacking epithelial responses including damage preventing dcy (drosocrystallin - a major component of the peritrophic matrix), damage signalling upd3 (unpaired protein, a cytokine-like molecule), damage controlling irc (immune-regulated catalase, a negative regulator of reactive oxygen species) and tissue damage repairing egfr1 (epidermal growth factor receptor). Overall, we detect effects of all these mechanisms on disease tolerance. The deterioration of the peritrophic matrix in dcy mutants resulted in the highest loss of tolerance, while loss of function of either irc or upd3 also reduced tolerance in both sexes. The absence of tissue damage repair signalling (egfr1) resulted in a severe loss in tolerance in male flies but had no substantial effect on the ability of female flies to tolerate P. entomophila infection, despite carrying greater microbe loads than males. Together, our findings provide empirical evidence for the role of damage limitation mechanisms in disease tolerance and highlight how sex differences in these mechanisms could generate sexual dimorphism in immunity.

scholarly journals The Jak/Stat pathway mediates disease tolerance during systemic bacterial infection in Drosophila

2021 ◽  
Author(s):  
Arun Prakash ◽  
Mickael Bonnet ◽  
Katy M. Monteith ◽  
Pedro F. Vale
Keyword(s):  
Bacterial Infection ◽  
Tissue Damage ◽  
Viral Infections ◽  
Systemic Infection ◽  
Negative Regulator ◽  
Sexually Dimorphic ◽  
Disease Tolerance ◽  
Males And Females ◽  
Systemic Bacterial Infection ◽  
Stat Pathway

Disease tolerance describes a hosts ability to maintain health independently of the ability to clear microbe loads. However, we currently know little about the mechanisms that underlie disease tolerance or how known mechanisms of tissue damage signalling and repair may contribute to variation in tolerance. The Jak/Stat pathway plays a pivotal role in Drosophila humoral innate immunity, signalling tissue damage and triggering cellular renewal, making it a potential mechanism underlying the disease tolerance phenotype. Here, we show that disrupting the Jak/Stat pathway in Drosophila melanogaster alters disease tolerance during Pseudomonas entomophila systemic infection. Overall, flies with disrupted Jak/Stat show variation in survival that is not explained by variation in pathogen loads. For instance, mutations disrupting the function of ROS producing dual oxidase (duox) or the negative regulator of Jak/Stat, Socs36E render males less tolerant to systemic bacterial infection but not females. We also investigated whether the negative regulator of Jak/Stat, G9a which has previously been associated with tolerance of viral infections is also implicated in tolerance of bacterial infection. While female flies lacking G9a showed higher mortality and reduced bacterial clearance, disease tolerance did not differ between G9a mutants and the wildtype. This suggests that G9a does not affect tolerance during systemic bacterial infection as it appears to do with viral infection. Overall, our findings highlight that Jak/Stat signalling mediates disease tolerance during systemic bacterial infection and that this response differs between males and females. Our work therefore suggests that differences in Jak/Stat mediated disease tolerance may be a potential source of sexually dimorphic response to infection in Drosophila.

A phase II study of everolimus in patients with aggressive RAI refractory (RAIR) thyroid cancer (TC).

2013 ◽  
Vol 31 (15_suppl) ◽  
pp. 6023-6023 ◽  
Author(s):  
Jochen H. Lorch ◽  
Naifa Busaidy ◽  
Daniel T Ruan ◽  
Pasi A. Janne ◽  
Sewanti Atul Limaye ◽  
...  
Keyword(s):  
Phase Ii ◽  
Phase Ii Study ◽  
Protein A ◽  
Progression Free Survival ◽  
Complete Response ◽  
Negative Regulator ◽  
High Rate ◽  
Loss Of Function ◽  
Open Label ◽  
Mechanistic Basis

6023 Background: We present results of an open label phase II study of the mTOR inhibitor Everolimus in patients (pts) with RAIR TC. Methods: Pts with metastatic, incurable RAIR TC who had shown radiographic progression within 6 months prior to enrollment received Everolimus 10mg orally once daily. Responses were monitored by CT's every two months. The primary endpoint was progression free survival. Sequential biopsies were obtained in selected pts. Results: Enrollment to the differentiated TC (DTC) cohort finished in Jan 2013 and included 33 pts, among them 11 with Hurthle cell TC. Exploratory cohorts enrolled 10 pts with medullary [MTC] and 5 with anaplastic [ATC] with 2 added openings remaining for ATC. For the DTC cohort, median time on study to date is 10 months (mo) (<1-23+). 31 pts are evaluable at this time. PFS in the DTC cohort by Kaplan-Meier (K-M) analysis is 16.0 mo (95%CI 10-NR). Currently, disease stability for 6 and 12 mo or more was achieved in 18 and 10/31 pts, respectively, 11 pts remain on study. Median OS was not reached but 1 year survival by K-M analysis was 76%. One pt achieved a PR. 3 pts with DTC underwent sequential biopsies which revealed activation of autophagy while markers for apoptosis were not detected. Among 10 MTC pts, one achieved a PR and 9 pts had stable disease for 6 mo or more (6-33+). Among 5 ATC pts, 3 progressed, one has ongoing disease stability for 5 mo. One patient achieved a complete response that lasted for 18 mo and whole exome sequencing revealed somatic loss of function mutation affecting the Tuberous Sclerosis 2 (TSC2) protein, a negative regulator of mTOR activity [TSC2 (Q1178*) and FLCN (R17fs)]. Most common treatment-related adverse events were as anticipated and included fatigue, stomatitis and infections. Grade (gr) 3 events included infection 5, weight loss 3, leukopenia 3, thrombocytopenia 3, fatigue 3, hypophosphatemia 2, stomatitis 2, pneumonitis 1 and thrombosis 1pts. One pt had gr 4 hypercholesterinemia and one pt had gr 4 leukopenia. Conclusions: Everolimus has significant anti-tumor activity in pts with advanced TC. Activation of autophagy could account for high rate of disease stability. Sequencing may identify mechanistic basis and predictive markers for treatment response. Clinical trial information: NCT00936858.

scholarly journals Identification of a GTPase-activating protein homolog in Schizosaccharomyces pombe.

1991 ◽  
Vol 11 (6) ◽  
pp. 3088-3094 ◽  
Author(s):  
Y Imai ◽  
S Miyake ◽  
D A Hughes ◽  
M Yamamoto
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Gene Product ◽  
Protein A ◽  
Negative Regulator ◽  
Loss Of Function ◽  
Gtpase Activating Protein ◽  
Ras Gtpase ◽  
Downstream Effector ◽  
Gtpase Cycle ◽  
Conserved Core

Loss of function of the Schizosaccharomyces pombe gap1 gene results in the same phenotypes as those caused by an activated ras1 mutation, i.e., hypersensitivity to the mating factor and inability to perform efficient mating. Sequence analysis of gap1 indicates that it encodes a homolog of the mammalian Ras GTPase-activating protein (GAP). The predicted gap1 gene product has 766 amino acids with relatively short N- and C-terminal regions flanking the conserved core sequence of GAP. Genetic analysis suggests that S. pombe Gap1 functions primarily as a negative regulator of Ras1, like S. cerevisiae GAP homologs encoded by IRA1 and IRA2, but is unlikely to be a downstream effector of the Ras protein, a role proposed for mammalian GAP. Thus, Gap1 and Ste6, a putative GDP-GTP-exchanging protein for Ras1 previously identified, appear to play antagonistic roles in the Ras-GTPase cycle in S. pombe. Furthermore, we suggest that this Ras-GTPase cycle involves the ra12 gene product, another positive regulator of Ras1 whose homologs have not been identified in other organisms, which could function either as a second GDP-GTP-exchanging protein or as a factor that negatively regulates Gap1 activity.

scholarly journals Identification of a GTPase-activating protein homolog in Schizosaccharomyces pombe

1991 ◽  
Vol 11 (6) ◽  
pp. 3088-3094 ◽  
Author(s):  
Y Imai ◽  
S Miyake ◽  
D A Hughes ◽  
M Yamamoto
Keyword(s):  
Schizosaccharomyces Pombe ◽  
Gene Product ◽  
Protein A ◽  
Negative Regulator ◽  
Loss Of Function ◽  
Gtpase Activating Protein ◽  
Ras Gtpase ◽  
Downstream Effector ◽  
Gtpase Cycle ◽  
Conserved Core

Loss of function of the Schizosaccharomyces pombe gap1 gene results in the same phenotypes as those caused by an activated ras1 mutation, i.e., hypersensitivity to the mating factor and inability to perform efficient mating. Sequence analysis of gap1 indicates that it encodes a homolog of the mammalian Ras GTPase-activating protein (GAP). The predicted gap1 gene product has 766 amino acids with relatively short N- and C-terminal regions flanking the conserved core sequence of GAP. Genetic analysis suggests that S. pombe Gap1 functions primarily as a negative regulator of Ras1, like S. cerevisiae GAP homologs encoded by IRA1 and IRA2, but is unlikely to be a downstream effector of the Ras protein, a role proposed for mammalian GAP. Thus, Gap1 and Ste6, a putative GDP-GTP-exchanging protein for Ras1 previously identified, appear to play antagonistic roles in the Ras-GTPase cycle in S. pombe. Furthermore, we suggest that this Ras-GTPase cycle involves the ra12 gene product, another positive regulator of Ras1 whose homologs have not been identified in other organisms, which could function either as a second GDP-GTP-exchanging protein or as a factor that negatively regulates Gap1 activity.

miR-126 regulates platelet-derived growth factor receptor-α expression and migration of primary human osteoblasts

2015 ◽  
Vol 396 (1) ◽  
pp. 61-70 ◽  
Author(s):  
Yvonne Schmidt ◽  
Filip Simunovic ◽  
Sandra Strassburg ◽  
Dietmar Pfeifer ◽  
G. Björn Stark ◽  
...  
Keyword(s):  
Growth Factor ◽  
Bone Development ◽  
Growth Factor Receptor ◽  
Cell Types ◽  
Negative Regulator ◽  
Platelet Derived Growth Factor ◽  
Loss Of Function ◽  
Human Osteoblasts ◽  
Primary Human Osteoblasts ◽  
And Migration

Abstract Adequate vascularization is an essential requirement for bone development, fracture healing and bone tissue engineering. We have previously described the coculture of primary human osteoblasts (hOBs) and human endothelial cells (HUVECs), designed to investigate the interactions between these cells. In this system, we showed that cocultivation of these two cell types leads to a downregulation of platelet-derived growth factor receptor-α (PDGFR-α) in hOBs, which was a consequence of reduced mRNA stability. In the current study we investigated the possible involvement of microRNAs in this process. Firstly, we performed a microarray analysis of osteoblastic miRNAs following cocultivation with HUVECs, revealing an upregulation of miR-126. This result was confirmed by RT-qPCR, and we observed that the increase is dependent on direct cell-to-cell contacts. Gain-of-function and loss-of-function experiments showed that miR-126 is a negative regulator of PDGFR-α mRNA. Additionally, migration of hOBs was inhibited by miR-126 overexpression and stimulated by miR-126 inhibition. Addition of PDGFR-α blocking antibody to hOB culture also inhibited hOB migration. There was no effect of miR-126 modulation on osteoblast proliferation, apoptosis rate or differentiation. In conclusion, we report that the miR-126/PDGFR-α system regulates the migratory behavior of human osteoblasts, without exerting effects on cell survival and differentiation.

scholarly journals LRIG1 is a conserved EGFR regulator involved in melanoma development, survival and treatment resistance

Oncogene ◽  
2021 ◽  
Author(s):  
Ola Billing ◽  
Ylva Holmgren ◽  
Daniel Nosek ◽  
Håkan Hedman ◽  
Oskar Hemmingsson
Keyword(s):  
Growth Factor Receptor ◽  
Braf Inhibitor ◽  
Treatment Resistance ◽  
Negative Regulator ◽  
C Elegans ◽  
Rtk Signaling ◽  
Egfr Expression ◽  
Inhibitor Resistance ◽  
Leucine Rich Repeats

AbstractLeucine-rich repeats and immunoglobulin-like domains 1 (LRIG1) is a pan-negative regulator of receptor tyrosine kinase (RTK) signaling and a tumor suppressor in several cancers, but its involvement in melanoma is largely unexplored. Here, we aim to determine the role of LRIG1 in melanoma tumorigenesis, RTK signaling, and BRAF inhibitor resistance. We find that LRIG1 is downregulated during early tumorigenesis and that LRIG1 affects activation of the epidermal growth factor receptor (EGFR) in melanoma cells. LRIG1-dependent regulation of EGFR signaling is evolutionary conserved to the roundworm C. elegans, where negative regulation of the EGFR-Ras-Raf pathway by sma-10/LRIG completely depends on presence of the receptor let-23/EGFR. In a cohort of metastatic melanoma patients, we observe an association between LRIG1 and survival in the triple wild-type subtype and in tumors with high EGFR expression. During in vitro development of BRAF inhibitor resistance, LRIG1 expression decreases; and mimics LRIG1 knockout cells for increased EGFR expression. Treating resistant cells with recombinant LRIG1 suppresses AKT activation and proliferation. Together, our results show that sma-10/LRIG is a conserved regulator of RTK signaling, add to our understanding of LRIG1 in melanoma and identifies recombinant LRIG1 as a potential therapeutic against BRAF inhibitor-resistant melanoma.

scholarly journals Genetic and Molecular Characterization of the Caenorhabditis elegans Gene, mel-26, a Postmeiotic Negative Regulator of MEI-1, a Meiotic-Specific Spindle Component

Genetics ◽  
1998 ◽  
Vol 150 (1) ◽  
pp. 119-128
Author(s):  
M Rhys Dow ◽  
Paul E Mains
Keyword(s):  
Caenorhabditis Elegans ◽  
Protein Interactions ◽  
Negative Regulator ◽  
Meiotic Spindle ◽  
Loss Of Function ◽  
Protein Protein Interactions ◽  
Gain Of Function ◽  
Recessive Mutations ◽  
Female Germline

Abstract We have previously described the gene mei-1, which encodes an essential component of the Caenorhabditis elegans meiotic spindle. When ectopically expressed after the completion of meiosis, mei-1 protein disrupts the function of the mitotic cleavage spindles. In this article, we describe the cloning and the further genetic characterization of mel-26, a postmeiotic negative regulator of mei-1. mel-26 was originally identified by a gain-of-function mutation. We have reverted this mutation to a loss-of-function allele, which has recessive phenotypes identical to the dominant defects of its gain-of-function parent. Both the dominant and recessive mutations of mel-26 result in mei-1 protein ectopically localized in mitotic spindles and centrosomes, leading to small and misoriented cleavage spindles. The loss-of-function mutation was used to clone mel-26 by transformation rescue. As suggested by genetic results indicating that mel-26 is required only maternally, mel-26 mRNA was expressed predominantly in the female germline. The gene encodes a protein that includes the BTB motif, which is thought to play a role in protein-protein interactions.

scholarly journals Biofilm Formation in Pseudomonas aeruginosa: Fimbrial cup Gene Clusters Are Controlled by the Transcriptional Regulator MvaT

2004 ◽  
Vol 186 (9) ◽  
pp. 2880-2890 ◽  
Author(s):  
Isabelle Vallet ◽  
Stephen P. Diggle ◽  
Rachael E. Stacey ◽  
Miguel Cámara ◽  
Isabelle Ventre ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Biofilm Formation ◽  
Dna Microarrays ◽  
Transcriptional Profiling ◽  
Bacterial Pathogen ◽  
Gene Clusters ◽  
Northern Blotting ◽  
Negative Regulator ◽  
Regulatory Control ◽  
Homologous Gene

ABSTRACT Pseudomonas aeruginosa is an opportunistic bacterial pathogen which poses a major threat to long-term-hospitalized patients and individuals with cystic fibrosis. The capacity of P. aeruginosa to form biofilms is an important requirement for chronic colonization of human tissues and for persistence in implanted medical devices. Various stages of biofilm formation by this organism are mediated by extracellular appendages, such as type IV pili and flagella. Recently, we identified three P. aeruginosa gene clusters that were termed cup (chaperone-usher pathway) based on their sequence relatedness to the chaperone-usher fimbrial assembly pathway in other bacteria. The cupA gene cluster, but not the cupB or cupC cluster, is required for biofilm formation on abiotic surfaces. In this study, we identified a gene (mvaT) encoding a negative regulator of cupA expression. Such regulatory control was confirmed by several approaches, including lacZ transcriptional fusions, Northern blotting, and transcriptional profiling using DNA microarrays. MvaT also represses the expression of the cupB and cupC genes, although the extent of the regulatory effect is not as pronounced as with cupA. Consistent with this finding, mvaT mutants exhibit enhanced biofilm formation. Although the P. aeruginosa genome contains a highly homologous gene, mvaU, the repression of cupA genes is MvaT specific. Thus, MvaT appears to be an important regulatory component within a complex network that controls biofilm formation and maturation in P. aeruginosa.

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