scholarly journals Deficiency in the autophagy modulator Dram1 exacerbates pyroptotic cell death of Mycobacteria-infected macrophages

2019 ◽  
Author(s):  
Rui Zhang ◽  
Monica Varela ◽  
Gabriel Forn-Cuni ◽  
Vincenzo Torraca ◽  
Michiel van der Vaart ◽  
...  
Keyword(s):  
Cell Death ◽  
Host Resistance ◽  
Transmembrane Protein ◽  
Mycobacterial Infection ◽  
Loss Of Function ◽  
Cellular Functions ◽  
Zebrafish Larvae ◽  
Cell Death Pathways ◽  
New Evidence

AbstractDNA Damage Regulated Autophagy Modulator 1 (DRAM1) is a stress-inducible regulator of autophagy and cell death. DRAM1 has been implicated in cancer, myocardial infarction, and infectious diseases, but the molecular and cellular functions of this transmembrane protein remain poorly understood. Previously, we have proposed DRAM1 as a host resistance factor for tuberculosis (TB) and a potential target for host-directed anti-infective therapies. In this study, we generated a zebrafish dram1 mutant and investigated its loss-of-function effects during Mycobacterium marinum (Mm) infection, a widely used model in TB research. In agreement with previous knockdown analysis, dram1 mutation increased the susceptibility of zebrafish larvae to Mm infection. RNA sequencing revealed major effects of Dram1 deficiency on metabolic, immune response, and cell death pathways during Mm infection, whereas only minor effects on proteinase and metabolic pathways were found under uninfected conditions. Furthermore, unchallenged dram1 mutants did not display overt autophagic defects, but autophagic targeting of Mm was reduced in absence of Dram1. The phagocytic ability of macrophages in dram1 mutants was unaffected, but acidification of Mm-containing vesicles was strongly reduced, indicating that Dram1 is required for phagosome maturation. By in vivo imaging we observed that Dram1-deficient macrophages fail to restrict Mm during early stages of infection. The resulting increase in bacterial burden could be reverted by knockdown of inflammatory caspase a (caspa) and gasdermin Eb (gsdmeb), demonstrating pyroptosis as the mechanism underlying premature cell death of Mm-infected macrophages in dram1 mutants. Collectively, these data demonstrate that dissemination of mycobacterial infection in zebrafish larvae is promoted in absence of Dram1 due to reduced maturation of mycobacteria-containing vesicles, failed intracellular containment, and consequent pyroptotic cell death of infected macrophages. These results provide new evidence that Dram1 plays a central role in host resistance to intracellular infection, acting at the crossroad of autophagy and cell death.

scholarly journals Roles for RNA export factor, Nxt1, in ensuring muscle integrity and normal RNA expression in Drosophila

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Kevin van der Graaf ◽  
Katia Jindrich ◽  
Robert Mitchell ◽  
Helen White-Cooper
Keyword(s):  
Mrna Export ◽  
Rna Stability ◽  
Muscle Degeneration ◽  
Loss Of Function ◽  
Cellular Functions ◽  
Partial Loss ◽  
Export Pathway ◽  
Pathway Gene ◽  
Rna Export

Abstract The mRNA export pathway is responsible for the transport of mRNAs from the nucleus to the cytoplasm, and thus is essential for protein production and normal cellular functions. A partial loss of function allele of the mRNA export factor Nxt1 in Drosophila shows reduced viability and sterility. A previous study has shown that the male fertility defect is due to a defect in transcription and RNA stability, indicating the potential for this pathway to be implicated in processes beyond the known mRNA transport function. Here we investigate the reduced viability of Nxt1 partial loss of function mutants, and describe a defect in growth and maintenance of the larval muscles, leading to muscle degeneration. RNA-seq revealed reduced expression of a set of mRNAs, particularly from genes with long introns in Nxt1 mutant carcass. We detected differential expression of circRNA, and significantly fewer distinct circRNAs expressed in the mutants. Despite the widespread defects in gene expression, muscle degeneration was rescued by increased expression of the costamere component tn (abba) in muscles. This is the first report of a role for the RNA export pathway gene Nxt1 in the maintenance of muscle integrity. Our data also links the mRNA export pathway to a specific role in the expression of mRNA and circRNA from common precursor genes, in vivo.

scholarly journals TCF12 haploinsufficiency causes autosomal dominant Kallmann syndrome and reveals network-level interactions between causal loci

2020 ◽  
Vol 29 (14) ◽  
pp. 2435-2450
Author(s):  
Erica E Davis ◽  
Ravikumar Balasubramanian ◽  
Zachary A Kupchinsky ◽  
David L Keefe ◽  
Lacey Plummer ◽  
...  
Keyword(s):  
Autosomal Recessive ◽  
Autosomal Dominant ◽  
Kallmann Syndrome ◽  
Gonadotropin Releasing Hormone ◽  
Loss Of Function ◽  
Binding Partner ◽  
Zebrafish Larvae ◽  
Syndromic Craniosynostosis ◽  
Molecular Components

Abstract Dysfunction of the gonadotropin-releasing hormone (GnRH) axis causes a range of reproductive phenotypes resulting from defects in the specification, migration and/or function of GnRH neurons. To identify additional molecular components of this system, we initiated a systematic genetic interrogation of families with isolated GnRH deficiency (IGD). Here, we report 13 families (12 autosomal dominant and one autosomal recessive) with an anosmic form of IGD (Kallmann syndrome) with loss-of-function mutations in TCF12, a locus also known to cause syndromic and non-syndromic craniosynostosis. We show that loss of tcf12 in zebrafish larvae perturbs GnRH neuronal patterning with concomitant attenuation of the orthologous expression of tcf3a/b, encoding a binding partner of TCF12, and stub1, a gene that is both mutated in other syndromic forms of IGD and maps to a TCF12 affinity network. Finally, we report that restored STUB1 mRNA rescues loss of tcf12 in vivo. Our data extend the mutational landscape of IGD, highlight the genetic links between craniofacial patterning and GnRH dysfunction and begin to assemble the functional network that regulates the development of the GnRH axis.

scholarly journals Loss offlflTriggers JNK-Dependent Cell Death inDrosophila

2015 ◽  
Vol 2015 ◽  
pp. 1-8 ◽  
Author(s):  
Jiuhong Huang ◽  
Lei Xue
Keyword(s):  
Cell Death ◽  
Function Analysis ◽  
Ectopic Expression ◽  
Negative Regulator ◽  
Loss Of Function ◽  
Jnk Pathway ◽  
Dependent Cell ◽  
Jnk Activation ◽  
First Time

falafel(flfl) encodes aDrosophilahomolog of human SMEK whosein vivofunctions remain elusive. In this study, we performed gain-of-function and loss-of-function analysis inDrosophilaand identified flfl as a negative regulator of JNK pathway-mediated cell death. While ectopic expression offlflsuppresses TNF-triggered JNK-dependent cell death, loss offlflpromotes JNK activation and cell death in the developing eye and wing. These data report for the first time an essential physiological function offlflin maintaining tissue homeostasis and organ development. As the JNK signaling pathway has been evolutionary conserved from fly to human, a similar role of PP4R3 in JNK-mediated physiological process is speculated.

scholarly journals PRMT5 epigenetically regulates the E3 ubiquitin ligase ITCH to influence lipid accumulation during mycobacterial infection

2021 ◽  
Author(s):  
Salik Miskat Borbora ◽  
R.S. Rajmani ◽  
Kithiganahalli N Balaji
Keyword(s):  
Ubiquitin Ligase ◽  
Lipid Accumulation ◽  
Ex Vivo ◽  
E3 Ubiquitin Ligase ◽  
Mycobacterial Infection ◽  
Drug Regimen ◽  
Loss Of Function ◽  
Methyl Transferase ◽  
Accumulation Of Lipids

Mycobacterium tuberculosis (Mtb), the causative agent of tuberculosis (TB), triggers enhanced accumulation of lipids to generate foamy macrophages (FMs). This process has been often attributed to the surge in the expression of lipid influx genes with a concomitant decrease in those involved in lipid efflux genes. Here, we define an Mtb-orchestrated modulation of the ubiquitination mechanism of lipid accumulation markers to enhance lipid accretion during infection. We find that Mtb infection represses the expression of the E3 ubiquitin ligase, ITCH, resulting in the sustenance of key lipid accrual molecules viz. ADRP and CD36, that are otherwise targeted by ITCH for proteasomal degradation. In line, overexpressing ITCH in Mtb-infected cells was found to suppress Mtb-induced lipid accumulation. Molecular analyses including loss-of-function and ChIP assays demonstrated a role for the concerted action of the transcription factor YY1 and the arginine methyl transferase PRMT5 in restricting the expression of Itch gene by conferring repressive symmetrical H4R3me2 marks on its promoter. Consequently, siRNA-mediated depletion of YY1 or PRMT5 rescued ITCH expression, thereby compromising the levels of Mtb-induced ADRP and CD36 and limiting FM formation during infection. Accumulation of lipids within the host has been implicated as a pro-mycobacterial process that aids in pathogen persistence and dormancy. In our study, perturbation of PRMT5 enzyme activity resulted in compromised lipid levels and reduced mycobacterial survival in primary murine macrophages (ex vivo) and in a therapeutic mouse model of TB infection (in vivo). These findings provide new insights on the role of PRMT5 and YY1 in augmenting mycobacterial pathogenesis. Thus, we posit that our observations could help design novel adjunct therapies and combinatorial drug regimen for effective anti-TB strategies.

scholarly journals MECOM permits pancreatic acinar cell dedifferentiation avoiding cell death under stress conditions

2020 ◽  
Author(s):  
Elyne Backx ◽  
Elke Wauters ◽  
Jonathan Baldan ◽  
Mathias Van Bulck ◽  
Ellis Michiels ◽  
...  
Keyword(s):  
Cell Death ◽  
Acinar Cell ◽  
Acinar Cells ◽  
Pancreatic Acinar Cell ◽  
Stress Conditions ◽  
Loss Of Function ◽  
Cell Dedifferentiation ◽  
Duct Cells

ABSTRACTMaintenance of the pancreatic acinar cell phenotype suppresses tumor formation. Hence, repetitive acute or chronic pancreatitis, stress conditions in which the acinar cells dedifferentiate, predispose for cancer formation in the pancreas. Dedifferentiated acinar cells acquire a large panel of duct cell specific markers. However, it remains unclear to what extent dedifferentiated acini differ from native duct cells and which genes are uniquely regulating acinar cell dedifferentiation. Moreover, most studies have been performed in mouse since the availability of human cells is scarce.Here, we applied a non-genetic lineage tracing method in our culture model of human pancreatic exocrine cells that allowed cell-type specific gene expression profiling by RNA sequencing. Subsequent to this discovery analysis, one transcription factor that was unique for dedifferentiated acinar cells was functionally characterized using in vitro and in vivo genetic loss-of-function experimental models.RNA sequencing analysis showed that human dedifferentiated acinar cells expressed genes in ‘Pathways of cancer’ with prominence of the transcription factor MECOM (EVI-1) that was absent from duct cells. During mouse embryonic development, pre-acinar cells transiently expressed MECOM and MECOM was re-expressed in experimental in vivo models of acute and chronic pancreatitis in vivo, conditions in which acinar cells dedifferentiate. MECOM expression correlated with and was directly regulated by SOX9. MECOM loss-of-function in mouse acinar cells in vitro and in vivo impaired cell adhesion resulting in more prominent acinar cell death and suppressed acinar cell dedifferentiation by limiting ERK signaling.In conclusion, we transcriptionally profiled the two major human pancreatic exocrine cell types, acinar and duct cells, during experimental stress conditions. We provide insights that in dedifferentiated acinar cells, cancer pathways are upregulated in which MECOM is a critical regulator that suppresses acinar cell death by permitting cellular dedifferentiation.

scholarly journals DOP86 An IFN-STAT1-MLKL axis drives programmed necrosis of Paneth cells in Crohn’s ileitis

2020 ◽  
Vol 14 (Supplement_1) ◽  
pp. S125-S126
Author(s):  
L HARTMANN ◽  
B Siegmund ◽  
C Weidinger ◽  
C Becker ◽  
M F Neurath ◽  
...  
Keyword(s):  
Cell Death ◽  
Intestinal Inflammation ◽  
Paneth Cell ◽  
Signalling Pathways ◽  
Caspase 8 ◽  
Programmed Necrosis ◽  
Cell Death Pathways ◽  
Small Intestinal

Abstract Background Interferons (IFNs) are immune-modulatory cytokines expressed by epithelial and mucosal cells in response to viral and bacterial infection. Just recently, we discovered a correlation between IFN-λ expression and disease activity, including small intestinal inflammation and Paneth cell dysfunction, in human Crohn’s disease patients. On a molecular level, we uncovered that IFN-λ mediates epithelial cell death, in particular, Paneth cell death by a programmed necrosis, dependent on STAT1 activation and controlled by caspase-8. These results suggested that IFN-λ can be considered as a pathogenic cytokine in Crohn′s ileitis and should be considered as a new and promising target for future therapeutic intervention for this particular subtype of IBD. Our central question is now by which pathways interferon-regulated programmed necrosis of epithelial cells contributes to intestinal inflammation and how these mechanisms could be targeted for future therapeutic intervention. Methods We use a mouse model for Crohn’s Disease like inflammation and Paneth cell death that has a specific deletion of Caspase-8 in intestinal epithelial cells (Casp8∆IEC). We stimulate small intestinal organoids derived from Casp8∆IEC mice with IFNs in vitro and we overexpress IFN-λ in these mice in vivo by hydrodynamic tail vein injection of an IFN-λ expression vector. Furthermore, we use JAK-inhibitors to impede pharmacologically cell death pathways in the pathogenesis of intestinal inflammation in vitro and in vivo. Results We uncovered that gene expression of the cell death mediators Mlkl and Caspase-8 is dependent on IFN-λ-mediated JAK-STAT1 signalling. The non-specific pan JAK-inhibitor Tofacitinib is able to attenuate gene expression of Mlkl and Caspase-8 in vitro as well as in vivo. It prevents non-apoptotic as well as apoptotic cell death of small intestinal organoids stimulated with IFN-λ and is sufficient to prevent small intestinal tissue destruction in Casp8∆IEC mice challenged with IFN-λ. Additionally, we use the selective JAK1-inhibitor Filgotinib to limit the targeted JAK-STAT signalling pathways to only JAK1-STAT1 signalling and thus reduce side effects of the inhibitor on other signalling pathways. This had a similar effect as Tofacitinib suggesting that IFN controls MLKL-mediated cell death via JAK1. Conclusion In summary, our results indicate that targeting IFN-λ-mediated JAK-STAT1 signalling by the small-molecules Tofacitinib and Filgotinib impedes induction of Mlkl and Caspase-8-mediated cell death pathways. Therefore, JAK1 inhibitors such as Filgotinib might represent a promising novel therapy that may be sufficient to achieve efficacy particularly in Crohn′s ileitis patients who display elevated IFN-l serum levels.

scholarly journals Downregulation of PUMA underlies resistance to FGFR1 inhibitors in the stem cell leukemia/lymphoma syndrome

2020 ◽  
Vol 11 (10) ◽  
Author(s):  
Yun Liu ◽  
Baohuan Cai ◽  
Yating Chong ◽  
Hualei Zhang ◽  
Chesley-Anne Kemp ◽  
...  
Keyword(s):  
Cell Death ◽  
Kinase Inhibitors ◽  
Leukemic Cells ◽  
Direct Role ◽  
Genetic Changes ◽  
Cell Death Pathways ◽  
Pten Deletion ◽  
Induced Apoptosis ◽  
Resistant Cells

Abstract Resistance to molecular therapies frequently occur due to genetic changes affecting the targeted pathway. In myeloid and lymphoid leukemias/lymphomas resulting from constitutive activation of FGFR1 kinases, resistance has been shown to be due either to mutations in FGFR1 or deletions of PTEN. RNA-Seq analysis of the resistant clones demonstrates expression changes in cell death pathways centering on the p53 upregulated modulator of apoptosis (Puma) protein. Treatment with different tyrosine kinase inhibitors (TKIs) revealed that, in both FGFR1 mutation and Pten deletion-mediated resistance, sustained Akt activation in resistant cells leads to compromised Puma activation, resulting in suppression of TKI-induced apoptosis. This suppression of Puma is achieved as a result of sequestration of inactivated p-Foxo3a in the cytoplasm. CRISPR/Cas9 mediated knockout of Puma in leukemic cells led to an increased drug resistance in the knockout cells demonstrating a direct role in TKI resistance. Since Puma promotes cell death by targeting Bcl2, TKI-resistant cells showed high Bcl2 levels and targeting Bcl2 with Venetoclax (ABT199) led to increased apoptosis in these cells. In vivo treatment of mice xenografted with resistant cells using ABT199 suppressed leukemogenesis and led to prolonged survival. This in-depth survey of the underlying genetic mechanisms of resistance has identified a potential means of treating FGFR1-driven malignancies that are resistant to FGFR1 inhibitors.

scholarly journals FTY720 induces non-canonical phosphatidylserine externalization and cell death in acute myeloid leukemia

2019 ◽  
Vol 10 (11) ◽  
Author(s):  
Megan M. Young ◽  
Van Bui ◽  
Chong Chen ◽  
Hong-Gang Wang
Keyword(s):  
Cell Death ◽  
Acute Myeloid Leukemia ◽  
Myeloid Leukemia ◽  
Membrane Integrity ◽  
Mechanistic Study ◽  
Flip Flop ◽  
Anticancer Efficacy ◽  
Cell Death Pathways ◽  
Acute Myeloid

Abstract FTY720 (fingolimod) is a FDA-approved sphingosine analog that is phosphorylated in vivo to modulate sphingosine-1-phosphate receptor (S1PR) signaling for immunosuppression in patients with refractory multiple sclerosis. FTY720 also exhibits promising anticancer efficacy in several preclinical models. While FTY720-induced cytotoxicity is not due to S1PR signaling, the mechanism remains unclear and is reported to occur through various cell death pathways. Here, we performed a systematic, mechanistic study of FTY720-induced cell death in acute myeloid leukemia (AML). We found that FTY720 induced cell death in a panel of genetically diverse AML cell lines that was accompanied by rapid phosphatidylserine (PS) externalization. Importantly, FTY720-induced PS exposure was not due to any direct effects on plasma membrane integrity and was independent of canonical signaling by regulated cell death pathways known to activate lipid flip-flop, including caspase-dependent apoptosis/pyroptosis, necroptosis, ferroptosis, and reactive oxygen species-mediated cell death. Notably, PS exposure required cellular vacuolization induced by defects in endocytic trafficking and was suppressed by the inhibition of PP2A and shedding of Annexin V-positive subcellular particles. Collectively, our studies reveal a non-canonical pathway underlying PS externalization and cell death in AML to provide mechanistic insight into the antitumor properties of FTY720.

DUSP4 inhibits autophagic cell death in PTC by inhibiting JNK-BCL2-Beclin1 signaling

2021 ◽  
Author(s):  
Huixiang He ◽  
zhenshuang Du ◽  
Jianqing Lin ◽  
Wenyi Wu ◽  
Yihuang Yu
Keyword(s):  
Cell Death ◽  
Specific Inhibitor ◽  
Autophagic Cell Death ◽  
Negative Regulator ◽  
Loss Of Function ◽  
In Vivo Assays ◽  
Prevention And Cure ◽  
The Relationship

DUSP4 is a prognostic marker and potential target of papillary thyroid carcinoma (PTC). However, the molecular mechanism underlying DUSP4-regulated PTC carcinogenesis is unclear. DUSP4 is a negative regulator of the autophagy promoter, JNK. This study aimed to explore the relationship between DUSP4 and JNK-mediated autophagic cell death in PTC. In this study, we explored the roles of DUSP4 in PTC using gain-of-function and loss-of-function assays. In addition, we further identified the significance of JNK-BCL2-Beclin1-autophagy signaling on DUSP4-regulated PTC carcinogenesis by combining DUSP4 silencing with JNK specific inhibitor (SP600125). We found that DUSP4 silencing promoted the phosphorylation of JNK and BCL2 in PTC cells and enhanced the release of Beclin1 from BCL2-Beclin1 complex. DUSP4 silencing promoted autophagy and death in PTC cells.The death and autophagy enhanced by DUSP4 silencing was reversed by JNK inhibitor. We further extended the in vitro experiments by injecting K1 cells transduced with DUSP4-silencing vector subcutaneously into nude mice. In vivo assays showed that DUSP4 silencing not only inhibited tumor growth, but also promoted JNK and BCL2 phosphorylation and LC3II expression.Overall, DUSP4 inhibits BCL2-Beclin1- autophagy signaling through negatively regulating JNK activity, thus inhibiting PTC oncogenesis.This study provides more potential clues for the prevention and cure of PTC.

scholarly journals "In vivo" toxicity of a truncated version of the Drosophila Rst-IrreC protein is dependent on the presence of a glutamine-rich region in its intracellular domain

2002 ◽  
Vol 74 (2) ◽  
pp. 285-295 ◽  
Author(s):  
RICARDO C. MACHADO ◽  
RODRIGO N.R. PEREIRA ◽  
MARA S.A. COSTA ◽  
RICARDO GUELERMAN P. RAMOS
Keyword(s):  
Cell Death ◽  
Programmed Cell Death ◽  
Compound Eye ◽  
Carboxyl Terminus ◽  
Loss Of Function ◽  
Rich Region ◽  
Characteristic Wave ◽  
Transmembrane Glycoprotein ◽  
Glutamine Rich Region

The roughest-irregular chiasm C ( rst-irreC) gene of Drosophila melanogaster encodes a transmembrane glycoprotein containing five immunoglobulin-like domains in its extracellular portion and an intracytoplasmic tail rich in serine and threonine as well some conserved motifs suggesting signal transduction activity. In the compound eye, loss-of-function rst-irreC mutants lack the characteristic wave of programmed cell death happening in early pupa and which is essential for the elimination of the surplus interommatidial cells. Here we report an investigation on the role played by the Rst-irreC molecule in triggering programmed cell death. "In vivo" transient expression assays showed that deletion of the last 80 amino acids of the carboxyl terminus produces a form of the protein that is highly toxic to larvae. This toxicity is suppressed if an additional 47 amino acid long, glutamine-rich region ("opa-like domain"), is also removed from the protein. The results suggest the possibility that the opa-like domain and the carboxyl terminus act in concert to modulate rst-irreC function in apoptosis, and we discuss this implication in the context of the general mechanisms causing glutamine-rich neurodegenerative diseases in humans.

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