scholarly journals The bacterial toxin CNF1 as a tool to induce retinal degeneration reminiscent of retinitis pigmentosa

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Viviana Guadagni ◽  
Chiara Cerri ◽  
Ilaria Piano ◽  
Elena Novelli ◽  
Claudia Gargini ◽  
...  
Keyword(s):  
Retinitis Pigmentosa ◽  
Retinal Degeneration ◽  
Rho Gtpase ◽  
Bacterial Toxin ◽  
Postnatal Life ◽  
Rodent Models ◽  
Photoreceptor Degeneration ◽  
Large Animals ◽  
Surgical Treatments ◽  
Cytotoxic Necrotizing Factor 1

Abstract Retinitis pigmentosa (RP) comprises a group of inherited pathologies characterized by progressive photoreceptor degeneration. In rodent models of RP, expression of defective genes and retinal degeneration usually manifest during the first weeks of postnatal life, making it difficult to distinguish consequences of primary genetic defects from abnormalities in retinal development. Moreover, mouse eyes are small and not always adequate to test pharmacological and surgical treatments. An inducible paradigm of retinal degeneration potentially extensible to large animals is therefore desirable. Starting from the serendipitous observation that intraocular injections of a Rho GTPase activator, the bacterial toxin Cytotoxic Necrotizing Factor 1 (CNF1), lead to retinal degeneration, we implemented an inducible model recapitulating most of the key features of Retinitis Pigmentosa. The model also unmasks an intrinsic vulnerability of photoreceptors to the mechanism of CNF1 action, indicating still unexplored molecular pathways potentially leading to the death of these cells in inherited forms of retinal degeneration.

scholarly journals Retinitis Pigmentosa Results in Neurodegeneration Concomitant With Neuroinflammation, Extracellular Matrix Disorganization and the Upregulation of Neuroprotective Pathways in Glial Cells and Neurons

2020 ◽  
Author(s):  
Christina B. Bielmeier ◽  
Saskia Roth ◽  
Sabrina I. Schmitt ◽  
Stefaniya K. Boneva ◽  
Anja Schlecht ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
Retinitis Pigmentosa ◽  
Retinal Degeneration ◽  
Molecular Mechanisms ◽  
Genetic Model ◽  
Immunofluorescent Staining ◽  
System Response ◽  
Photoreceptor Degeneration ◽  
The Impact

Abstract BackgroundHereditary retinal degenerations like retinitis pigmentosa (RP) are amongst the leading causes of blindness in younger patients. To enable in vivo investigation of cellular and molecular mechanisms responsible for photoreceptor cell death and to allow testing of therapeutic strategies that could prevent retinal degeneration, animal models have been created. Here, we in-depth characterized the transgenic VPP mouse model, a genetic model for autosomal dominant RP. MethodsWe examined the degree of photoreceptor degeneration and studied the impact of the VPP transgene-induced retinal degeneration on the transcriptome level of the retina using next generation RNA sequencing (RNASeq) analyses followed by weighted correlation network analysis (WGCNA). We furthermore identified cellular subpopulations responsible for some of the observed dysregulations using in situ hybridizations, immunofluorescent staining and 3D reconstruction. ResultsOne month-old VPP mice showed a significantly higher number of apoptotic photoreceptor cells that resulted in a significantly thinner ONL in three months-old VPP mice, concomitant with an increase in reactivity of microglia and Müller cells. By RNASeq analysis we identified 9,256 dysregulated genes and six significantly associated gene modules in the subsequently performed WGCNA. Gene ontology enrichment showed, amongst others, dysregulation of TGF-β regulated extracellular matrix organization, factors of the (ocular) immune system/response and apoptosis. ConclusionThe predominant effect pointed towards induction of neuroinflammation and the upregulation of neuroprotective pathways like TGF-β, G-protein activated and VEGF signaling that were significantly associated with the VPP transgene-induced photoreceptor degeneration. Thus, modulation of these processes might represent new therapeutic options to delay the degeneration of photoreceptors in diseases like RP.

scholarly journals Cytotoxic Necrotizing Factor 1 Prevents Apoptosis via the Akt/IκB Kinase Pathway: Role of Nuclear Factor-κB and Bcl-2

2007 ◽  
Vol 18 (7) ◽  
pp. 2735-2744 ◽  
Author(s):  
Alessandro Giamboi Miraglia ◽  
Sara Travaglione ◽  
Stefania Meschini ◽  
Loredana Falzano ◽  
Paola Matarrese ◽  
...  
Keyword(s):  
Rho Gtpase ◽  
Nuclear Factor Κb ◽  
Ultraviolet B ◽  
Bacterial Toxin ◽  
Nuclear Factor ◽  
Mitochondrial Network ◽  
Cytotoxic Necrotizing Factor ◽  
Protein Toxin ◽  
Iκb Kinase ◽  
Cytotoxic Necrotizing Factor 1

Cytotoxic necrotizing factor 1 (CNF1) is a protein toxin produced by some pathogenic strains of Escherichia coli that specifically activates Rho, Rac, and Cdc42 GTPases. We previously reported that this toxin prevents the ultraviolet-B–induced apoptosis in epithelial cells, with a mechanism that remained to be defined. In this work, we show that the proteasomal degradation of the Rho GTPase is necessary to achieve cell death protection, because inhibition of Rho degradation abolishes the prosurvival activity of CNF1. We hypothesize that Rho inactivation allows the activity of Rac to become dominant. This in turn leads to stimulation of the phosphoinositide 3-kinase/Akt/IκB kinase/nuclear factor-κB prosurvival pathway and to a remarkable modification in the architecture of the mitochondrial network, mainly consisting in the appearance of elongated and interconnected mitochondria. Importantly, we found that Bcl-2 silencing reduces the ability of CNF1 to protect cells against apoptosis and that it also prevents the CNF1-induced mitochondrial changes. It is worth noting that the ability of a bacterial toxin to induce such a remodeling of the mitochondrial network is herein reported for the first time. The possible pathophysiological relevance of this finding is discussed.

scholarly journals Transcriptional Profiling Identifies Upregulation of Neuroprotective Pathways in Retinitis Pigmentosa

2021 ◽  
Vol 22 (12) ◽  
pp. 6307
Author(s):  
Christina B. Bielmeier ◽  
Saskia Roth ◽  
Sabrina I. Schmitt ◽  
Stefaniya K. Boneva ◽  
Anja Schlecht ◽  
...  
Keyword(s):  
Retinitis Pigmentosa ◽  
Signaling Pathways ◽  
Retinal Degeneration ◽  
G Protein ◽  
Molecular Mechanisms ◽  
System Response ◽  
Photoreceptor Degeneration ◽  
Vegf Signaling ◽  
The Impact

Hereditary retinal degenerations like retinitis pigmentosa (RP) are among the leading causes of blindness in younger patients. To enable in vivo investigation of cellular and molecular mechanisms responsible for photoreceptor cell death and to allow testing of therapeutic strategies that could prevent retinal degeneration, animal models have been created. In this study, we deeply characterized the transcriptional profile of mice carrying the transgene rhodopsin V20G/P23H/P27L (VPP), which is a model for autosomal dominant RP. We examined the degree of photoreceptor degeneration and studied the impact of the VPP transgene-induced retinal degeneration on the transcriptome level of the retina using next generation RNA sequencing (RNASeq) analyses followed by weighted correlation network analysis (WGCNA). We furthermore identified cellular subpopulations responsible for some of the observed dysregulations using in situ hybridizations, immunofluorescence staining, and 3D reconstruction. Using RNASeq analysis, we identified 9256 dysregulated genes and six significantly associated gene modules in the subsequently performed WGCNA. Gene ontology enrichment showed, among others, dysregulation of genes involved in TGF-β regulated extracellular matrix organization, the (ocular) immune system/response, and cellular homeostasis. Moreover, heatmaps confirmed clustering of significantly dysregulated genes coding for components of the TGF-β, G-protein activated, and VEGF signaling pathway. 3D reconstructions of immunostained/in situ hybridized sections revealed retinal neurons and Müller cells as the major cellular population expressing representative components of these signaling pathways. The predominant effect of VPP-induced photoreceptor degeneration pointed towards induction of neuroinflammation and the upregulation of neuroprotective pathways like TGF-β, G-protein activated, and VEGF signaling. Thus, modulation of these processes and signaling pathways might represent new therapeutic options to delay the degeneration of photoreceptors in diseases like RP.

scholarly journals Actin Can Reorganize into Podosomes in Aortic Endothelial Cells, a Process Controlled by Cdc42 and RhoA

2003 ◽  
Vol 23 (19) ◽  
pp. 6809-6822 ◽  
Author(s):  
Violaine Moreau ◽  
Florence Tatin ◽  
Christine Varon ◽  
Elisabeth Génot
Keyword(s):  
Endothelial Cells ◽  
Rho Gtpase ◽  
Bacterial Toxin ◽  
Cell Physiology ◽  
Filamentous Actin ◽  
Aortic Endothelial Cells ◽  
Cytotoxic Necrotizing Factor 1 ◽  
Cytoskeletal Rearrangements ◽  
Syndrome Protein ◽  
First Time

ABSTRACT Members of the Rho GTPase family play a central role in the orchestration of cytoskeletal rearrangements, which are of prime importance in endothelial cell physiology. To explore their role in this specialized cell type, we used the bacterial toxin cytotoxic necrotizing factor 1 (CNF1) as a Rho GTPase activator. Punctate filamentous actin structures appeared along the ventral plasma membrane of endothelial cells and were identified as the core of podosomes by the distinctive vinculin ring around the F-actin. Rho, Rac, and Cdc42 were all identified as targets of CNF1, but only a constitutively active mutant of Cdc42 could substitute for CNF1 in podosome induction. Accordingly, organization of F-actin in these structures was highly dependent on the main Cdc42 cytoskeletal effector N-Wiskott-Aldrich syndrome protein. Other components of the actin machinery such as Arp2/3 and for the first time WIP also colocalized at these sites. Like CNF1 treatment, sustained Cdc42 activity induced a time-dependent F-actin-vinculin reorganization, prevented cytokinesis, and downregulated Rho activity. Finally, podosomes were also detected on endothelial cells explanted from patients undergoing cardiac surgery. These data provide the first description of podosomes in endothelial cells. The identification of such specialized structures opens up a new field of investigation in terms of endothelium pathophysiology.

scholarly journals Ciliary Genes arl13b, ahi1 and cc2d2a Differentially Modify Expression of Visual Acuity Phenotypes but do not Enhance Retinal Degeneration due to Mutation of cep290 in Zebrafish

2019 ◽  
Author(s):  
Emma M. Lessieur ◽  
Ping Song ◽  
Gabrielle C. Nivar ◽  
Ellen M. Piccillo ◽  
Joseph Fogerty ◽  
...  
Keyword(s):  
Retinitis Pigmentosa ◽  
Retinal Degeneration ◽  
Joubert Syndrome ◽  
Genetic Modifiers ◽  
Photoreceptor Degeneration ◽  
Optokinetic Response ◽  
Bardet Biedl Syndrome ◽  
Leber Congenital Amaurosis ◽  
Outer Segments ◽  
Rhodopsin Kinase

ABSTRACTMutations in the gene Centrosomal Protein 290 kDa (CEP290) result in multiple ciliopathies ranging from the neonatal lethal disorder Meckel-Gruber Syndrome to multi-systemic disorders such as Joubert Syndrome and Bardet-Biedl Syndrome to nonsyndromic diseases like Leber Congenital Amaurosis (LCA) and retinitis pigmentosa. Results from model organisms and human genetics studies, have suggest that mutations in genes encoding protein components of the transition zone (TZ) and other cilia-associated proteins can function as genetic modifiers and be a source for CEP290 pleiotropy. We investigated the zebrafish cep290fh297/fh297 mutant, which encodes a nonsense mutation (p.Q1217*). This mutant is viable as adults, exhibits scoliosis, and undergoes a slow, progressive cone degeneration. The cep290fh297/fh297 mutants showed partial mislocalization of the transmembrane protein rhodopsin but not of the prenylated proteins rhodopsin kinase (GRK1) or the rod transducin subunit GNB1. Surprisingly, photoreceptor degeneration did not trigger proliferation of Müller glia, but proliferation of rod progenitors in the outer nuclear layer was significantly increased. To determine if heterozygous mutations in other cilia genes could exacerbate retinal degeneration, we bred cep290fh297/fh297 mutants to arl13b, ahi1, and cc2d2a mutant zebrafish lines. While cep290fh297/fh297 mutants lacking a single allele of these genes did not exhibit accelerated photoreceptor degeneration, loss of one alleles of arl13b or ahi1 reduced visual performance in optokinetic response assays at 5 days post fertilization. Our results indicate that the cep290fh297/fh297 mutant is a useful model to study the role of genetic modifiers on photoreceptor degeneration in zebrafish and to explore how progressive photoreceptor degeneration influences regeneration in adult zebrafish.Nonstandard abbreviationsBBSBardet-Biedl SyndromeCOScone outer segmentsDpfDays post fertilizationGNB1rod transducin β subunitGRK1rhodopsin kinaseJTBSJoubert SyndromeLCALeber Congenital AmaurosisMKSMeckel SyndromeNPHPnephronophthisisOKRoptokinetic responsePNApeanut agglutinin lectinROSrod outer segmentsRP2Retinitis Pigmentosa 2

scholarly journals Erratum: Corrigendum: The bacterial toxin CNF1 as a tool to induce retinal degeneration reminiscent of retinitis pigmentosa

2016 ◽  
Vol 6 (1) ◽  
Author(s):  
Viviana Guadagni ◽  
Chiara Cerri ◽  
Ilaria Piano ◽  
Elena Novelli ◽  
Claudia Gargini ◽  
...  
Keyword(s):  
Retinitis Pigmentosa ◽  
Retinal Degeneration ◽  
Bacterial Toxin

scholarly journals rdgE: A Novel Retinal Degeneration Mutation in Drosophila melanogaster

Genetics ◽  
1996 ◽  
Vol 144 (1) ◽  
pp. 127-138
Author(s):  
Troy Zars ◽  
David R Hyde
Keyword(s):  
Electron Microscopy ◽  
Retinal Degeneration ◽  
Light Response ◽  
Neuronal Membrane ◽  
Constant Darkness ◽  
Multivesicular Bodies ◽  
Photoreceptor Degeneration ◽  
Transmission Electron ◽  
Phototransduction Cascade ◽  
Membrane Biosynthesis

Abstract We report isolating the Drosophila retinal degeneration E (rdgE) mutation. The hypomorphic rdgE  1 allele causes rapid photoreceptor degeneration in light and a slower rate of degeneration when the flies are raised in constant darkness. The rdgE  1 flies exhibited an electrophysiological light response that decreased with age, coinciding with the degeneration. This suggests that degeneration caused the loss of the light response. We determined that the ninaE (rhodopsin) mutation, but not norpA [phospholipase C (PLC)], slowed the rdgE-dependent degeneration. This was consistent with the light-enhanced degeneration, but revealed that the degeneration is independent of the PLC-mediated phototransduction cascade. Transmission electron microscopy revealed that rdgE  1 photoreceptors exhibited a number of vesicular transport defects including unpacking/vesiculation of rhabdomeres, endocytosis of novel vesicles by photoreceptors, a buildup of very large multivesicular bodies, and an increased amount of rough endoplasmic reticulum. We determined that the rdgE null phenotype is a late embryonic lethality. Therefore, rdgE  + is required in cells outside of the retina, quite possibly in a large number of neurons. Thus, rdgE may define a mutational class that exhibits both light-enhanced retinal degeneration and a recessive null lethality by perturbing neuronal membrane biosynthesis and/or recycling.

Short-term high-fat feeding exacerbates degeneration in retinitis pigmentosa by promoting retinal oxidative stress and inflammation

2021 ◽  
Vol 118 (43) ◽  
pp. e2100566118
Author(s):  
Oksana Kutsyr ◽  
Agustina Noailles ◽  
Natalia Martínez-Gil ◽  
Lucía Maestre-Carballa ◽  
Manuel Martinez-Garcia ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Retinitis Pigmentosa ◽  
Retinal Degeneration ◽  
Gut Microbiome ◽  
Cell Activation ◽  
High Fat ◽  
Short Term ◽  
Oxidative Markers ◽  
Degenerative Disorders ◽  
Inflammatory State

A high-fat diet (HFD) can induce hyperglycemia and metabolic syndromes that, in turn, can trigger visual impairment. To evaluate the acute effects of HFD feeding on retinal degeneration, we assessed retinal function and morphology, inflammatory state, oxidative stress, and gut microbiome in dystrophic retinal degeneration 10 (rd10) mice, a model of retinitis pigmentosa, fed an HFD for 2 to 3 wk. Short-term HFD feeding impaired retinal responsiveness and visual acuity and enhanced photoreceptor degeneration, microglial cell activation, and Müller cell gliosis. HFD consumption also triggered the expression of inflammatory and oxidative markers in rd10 retinas. Finally, an HFD caused gut microbiome dysbiosis, increasing the abundance of potentially proinflammatory bacteria. Thus, HFD feeding drives the pathological processes of retinal degeneration by promoting oxidative stress and activating inflammatory-related pathways. Our findings suggest that consumption of an HFD could accelerate the progression of the disease in patients with retinal degenerative disorders.

scholarly journals Redefining the role of Ca2+-permeable channels in photoreceptor degeneration using diltiazem

2022 ◽  
Vol 13 (1) ◽  
Author(s):  
Soumyaparna Das ◽  
Valerie Popp ◽  
Michael Power ◽  
Kathrin Groeneveld ◽  
Jie Yan ◽  
...  
Keyword(s):  
Cell Death ◽  
Retinal Degeneration ◽  
Photoreceptor Cell ◽  
Strong Increase ◽  
Channel Blockers ◽  
Photoreceptor Degeneration ◽  
Therapy Development ◽  
Hypertensive Drug ◽  
Future Therapy

AbstractHereditary degeneration of photoreceptors has been linked to over-activation of Ca2+-permeable channels, excessive Ca2+-influx, and downstream activation of Ca2+-dependent calpain-type proteases. Unfortunately, after more than 20 years of pertinent research, unequivocal evidence proving significant and reproducible photoreceptor protection with Ca2+-channel blockers is still lacking. Here, we show that both D- and L-cis enantiomers of the anti-hypertensive drug diltiazem were very effective at blocking photoreceptor Ca2+-influx, most probably by blocking the pore of Ca2+-permeable channels. Yet, unexpectedly, this block neither reduced the activity of calpain-type proteases, nor did it result in photoreceptor protection. Remarkably, application of the L-cis enantiomer of diltiazem even led to a strong increase in photoreceptor cell death. These findings shed doubt on the previously proposed links between Ca2+ and retinal degeneration and are highly relevant for future therapy development as they may serve to refocus research efforts towards alternative, Ca2+-independent degenerative mechanisms.

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