scholarly journals The caspase-6–p62 axis modulates p62 droplets based autophagy in a dominant-negative manner

2021 ◽  
Author(s):  
Evelina Valionyte ◽  
Yi Yang ◽  
Sophie A. Griffiths ◽  
Amelia T. Bone ◽  
Elizabeth R. Barrow ◽  
...  
Keyword(s):  
Droplet Formation ◽  
Cleavage Product ◽  
Dominant Negative ◽  
Autophagosome Formation ◽  
Cellular Models ◽  
Pathological Conditions ◽  
Negative Role ◽  
Caspase 6 ◽  
Inflammatory Toxicity

AbstractSQSTM1/p62, as a major autophagy receptor, forms droplets that are critical for cargo recognition, nucleation, and clearance. p62 droplets also function as liquid assembly platforms to allow the formation of autophagosomes at their surfaces. It is unknown how p62-droplet formation is regulated under physiological or pathological conditions. Here, we report that p62-droplet formation is selectively blocked by inflammatory toxicity, which induces cleavage of p62 by caspase-6 at a novel cleavage site D256, a conserved site across human, mouse, rat, and zebrafish. The N-terminal cleavage product is relatively stable, whereas the C-terminal product appears undetectable. Using a variety of cellular models, we show that the p62 N-terminal caspase-6 cleavage product (p62-N) plays a dominant-negative role to block p62-droplet formation. In vitro p62 phase separation assays confirm this observation. Dominant-negative regulation of p62-droplet formation by caspase-6 cleavage attenuates p62 droplets dependent autophagosome formation. Our study suggests a novel pathway to modulate autophagy through the caspase-6–p62 axis under certain stress stimuli.

scholarly journals Caspase Cleavage of Keratin 18 and Reorganization of Intermediate Filaments during Epithelial Cell Apoptosis

1997 ◽  
Vol 138 (6) ◽  
pp. 1379-1394 ◽  
Author(s):  
Carlos Caulín ◽  
Guy S. Salvesen ◽  
Robert G. Oshima
Keyword(s):  
Intermediate Filaments ◽  
Cleavage Site ◽  
Uv Light ◽  
Tail Domain ◽  
Proteolytic Fragment ◽  
Intermediate Filament Proteins ◽  
Caspase Cleavage ◽  
Structural Cell ◽  
Caspase 6

Keratins 8 (K8) and 18 (K18) are major components of intermediate filaments (IFs) of simple epithelial cells and tumors derived from such cells. Structural cell changes during apoptosis are mediated by proteases of the caspase family. During apoptosis, K18 IFs reorganize into granular structures enriched for K18 phosphorylated on serine 53. K18, but not K8, generates a proteolytic fragment during drug- and UV light–induced apoptosis; this fragment comigrates with K18 cleaved in vitro by caspase-6, -3, and -7. K18 is cleaved by caspase-6 into NH2-terminal, 26-kD and COOH-terminal, 22-kD fragments; caspase-3 and -7 additionally cleave the 22-kD fragment into a 19-kD fragment. The cleavage site common for the three caspases was the sequence VEVD/A, located in the conserved L1-2 linker region of K18. The additional site for caspases-3 and -7 that is not cleaved efficiently by caspase-6 is located in the COOH-terminal tail domain of K18. Expression of K18 with alanine instead of serine at position 53 demonstrated that cleavage during apoptosis does not require phosphorylation of serine 53. However, K18 with a glutamate instead of aspartate at position 238 was resistant to proteolysis during apoptosis. Furthermore, this cleavage site mutant appears to cause keratin filament reorganization in stably transfected clones. The identification of the L1-2 caspase cleavage site, and the conservation of the same or very similar sites in multiple other intermediate filament proteins, suggests that the processing of IFs during apoptosis may be initiated by a similar caspase cleavage.

scholarly journals Albumin in patients with liver disease shows an altered conformation

2021 ◽  
Vol 4 (1) ◽  
Author(s):  
Margret Paar ◽  
Vera H. Fengler ◽  
Daniel J. Rosenberg ◽  
Angelika Krebs ◽  
Rudolf E. Stauber ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Liver Disease ◽  
Chronic Liver Disease ◽  
Chronic Liver ◽  
X Ray Scattering ◽  
Pathological Conditions ◽  
Healthy Donors ◽  
Relevant Variables ◽  
End Stage

AbstractHuman serum albumin (HSA) constitutes the primary transporter of fatty acids, bilirubin, and other plasma compounds. The binding, transport, and release of its cargos strongly depend on albumin conformation, which is affected by bound ligands induced by physiological and pathological conditions. HSA is both highly oxidized and heavily loaded with fatty acids and bilirubin in chronic liver disease. By employing small-angle X-ray scattering we show that HSA from the plasma of chronic liver disease patients undergoes a distinct opening compared to healthy donors. The extent of HSA opening correlates with clinically relevant variables, such as the model of end-stage liver disease score, bilirubin, and fatty acid levels. Although the mild oxidation of HSA in vitro does not alter overall structure, the alteration of patients’ HSA correlates with its redox state. This study connects clinical data with structural visualization of albumin dynamicity in solution and underlines the functional importance of albumin’s inherent flexibility.

scholarly journals The Revolutionary Roads to Study Cell–Cell Interactions in 3D In Vitro Pancreatic Cancer Models

Cancers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 930
Author(s):  
Donatella Delle Cave ◽  
Riccardo Rizzo ◽  
Bruno Sainz ◽  
Giuseppe Gigli ◽  
Loretta L. del Mercato ◽  
...  
Keyword(s):  
Pancreatic Cancer ◽  
Therapeutic Response ◽  
Three Dimensional ◽  
Cellular Models ◽  
Common Cancer ◽  
Cancer Models ◽  
Anti Cancer ◽  
Tumor Environment

Pancreatic cancer, the fourth most common cancer worldwide, shows a highly unsuccessful therapeutic response. In the last 10 years, neither important advancements nor new therapeutic strategies have significantly impacted patient survival, highlighting the need to pursue new avenues for drug development discovery and design. Advanced cellular models, resembling as much as possible the original in vivo tumor environment, may be more successful in predicting the efficacy of future anti-cancer candidates in clinical trials. In this review, we discuss novel bioengineered platforms for anticancer drug discovery in pancreatic cancer, from traditional two-dimensional models to innovative three-dimensional ones.

scholarly journals The Current Challenges for Drug Discovery in CNS Remyelination

2021 ◽  
Vol 22 (6) ◽  
pp. 2891
Author(s):  
Sonia Balestri ◽  
Alice Del Giovane ◽  
Carola Sposato ◽  
Marta Ferrarelli ◽  
Antonella Ragnini-Wilson
Keyword(s):  
Drug Screening ◽  
Myelin Sheath ◽  
Time Window ◽  
In Vitro Models ◽  
Adult Brain ◽  
Pharmacological Intervention ◽  
Cellular Models ◽  
New Findings ◽  
Myelin Injury

The myelin sheath wraps around axons, allowing saltatory currents to be transmitted along neurons. Several genetic, viral, or environmental factors can damage the central nervous system (CNS) myelin sheath during life. Unless the myelin sheath is repaired, these insults will lead to neurodegeneration. Remyelination occurs spontaneously upon myelin injury in healthy individuals but can fail in several demyelination pathologies or as a consequence of aging. Thus, pharmacological intervention that promotes CNS remyelination could have a major impact on patient’s lives by delaying or even preventing neurodegeneration. Drugs promoting CNS remyelination in animal models have been identified recently, mostly as a result of repurposing phenotypical screening campaigns that used novel oligodendrocyte cellular models. Although none of these have as yet arrived in the clinic, promising candidates are on the way. Many questions remain. Among the most relevant is the question if there is a time window when remyelination drugs should be administrated and why adult remyelination fails in many neurodegenerative pathologies. Moreover, a significant challenge in the field is how to reconstitute the oligodendrocyte/axon interaction environment representative of healthy as well as disease microenvironments in drug screening campaigns, so that drugs can be screened in the most appropriate disease-relevant conditions. Here we will provide an overview of how the field of in vitro models developed over recent years and recent biological findings about how oligodendrocytes mature after reactivation of their staminal niche. These data have posed novel questions and opened new views about how the adult brain is repaired after myelin injury and we will discuss how these new findings might change future drug screening campaigns for CNS regenerative drugs.

scholarly journals Effects of Platelet-Rich Plasma on Cellular Populations of the Central Nervous System: The Influence of Donor Age

2021 ◽  
Vol 22 (4) ◽  
pp. 1725
Author(s):  
Diego Delgado ◽  
Ane Miren Bilbao ◽  
Maider Beitia ◽  
Ane Garate ◽  
Pello Sánchez ◽  
...  
Keyword(s):  
Central Nervous System ◽  
Nervous System ◽  
Cellular Response ◽  
Platelet Rich Plasma ◽  
Biological Response ◽  
In Vitro Models ◽  
Molecular Composition ◽  
Cellular Models ◽  
The Central Nervous System

Platelet-rich plasma (PRP) is a biologic therapy that promotes healing responses across multiple medical fields, including the central nervous system (CNS). The efficacy of this therapy depends on several factors such as the donor’s health status and age. This work aims to prove the effect of PRP on cellular models of the CNS, considering the differences between PRP from young and elderly donors. Two different PRP pools were prepared from donors 65–85 and 20–25 years old. The cellular and molecular composition of both PRPs were analyzed. Subsequently, the cellular response was evaluated in CNS in vitro models, studying proliferation, neurogenesis, synaptogenesis, and inflammation. While no differences in the cellular composition of PRPs were found, the molecular composition of the Young PRP showed lower levels of inflammatory molecules such as CCL-11, as well as the presence of other factors not found in Aged PRP (GDF-11). Although both PRPs had effects in terms of reducing neural progenitor cell apoptosis, stabilizing neuronal synapses, and decreasing inflammation in the microglia, the effect of the Young PRP was more pronounced. In conclusion, the molecular composition of the PRP, conditioned by the age of the donors, affects the magnitude of the biological response.

scholarly journals Restoration of Silencing in Saccharomyces cerevisiae by Tethering of a Novel Sir2-Interacting Protein, Esc8

Genetics ◽  
2002 ◽  
Vol 162 (2) ◽  
pp. 633-645 ◽  
Author(s):  
Guido Cuperus ◽  
David Shore
Keyword(s):  
Protein A ◽  
Dominant Negative ◽  
Class I ◽  
Dominant Negative Effect ◽  
Rna Pol Ii ◽  
Interacting Protein ◽  
Nucleosome Remodeling ◽  
Negative Effect ◽  
Close Homolog

Abstract We previously described two classes of SIR2 mutations specifically defective in either telomeric/HM silencing (class I) or rDNA silencing (class II) in S. cerevisiae. Here we report the identification of genes whose protein products, when either overexpressed or directly tethered to the locus in question, can establish silencing in SIR2 class I mutants. Elevated dosage of SCS2, previously implicated as a regulator of both inositol biosynthesis and telomeric silencing, suppressed the dominant-negative effect of a SIR2-143 mutation. In a genetic screen for proteins that restore silencing when tethered to a telomere, we isolated ESC2 and an uncharacterized gene, (YOL017w), which we call ESC8. Both Esc2p and Esc8p interact with Sir2p in two-hybrid assays, and the Esc8p-Sir2 interaction is detected in vitro. Interestingly, Esc8p has a single close homolog in yeast, the ISW1-complex factor Ioc3p, and has also been copurified with Isw1p, raising the possibility that Esc8p is a component of an Isw1p-containing nucleosome remodeling complex. Whereas esc2 and esc8 deletion mutants alone have only marginal silencing defects, cells lacking Isw1p show a strong silencing defect at HMR but not at telomeres. Finally, we show that Esc8p interacts with the Gal11 protein, a component of the RNA pol II mediator complex.

scholarly journals Dominant Negative Mutants Implicate STAT5 in Myeloid Cell Proliferation and Neutrophil Differentiation

Blood ◽  
1999 ◽  
Vol 93 (12) ◽  
pp. 4154-4166 ◽  
Author(s):  
Robert L. Ilaria ◽  
Robert G. Hawley ◽  
Richard A. Van Etten
Keyword(s):  
Dna Binding ◽  
Transcriptional Activation ◽  
Dominant Negative ◽  
Dominant Negative Effect ◽  
Cytokine Signaling ◽  
Transactivation Domain ◽  
Negative Effects ◽  
Murine Bone Marrow ◽  
Negative Effect

Abstract STAT5 is a member of the signal transducers and activation of transcription (STAT) family of latent transcription factors activated in a variety of cytokine signaling pathways. We introduced alanine substitution mutations in highly conserved regions of murine STAT5A and studied the mutants for dimerization, DNA binding, transactivation, and dominant negative effects on erythropoietin-induced STAT5-dependent transcriptional activation. The mutations included two near the amino-terminus (W255KR→AAA and R290QQ→AAA), two in the DNA-binding domain (E437E→AA and V466VV→AAA), and a carboxy-terminal truncation of STAT5A (STAT5A/▵53C) analogous to a naturally occurring isoform of rat STAT5B. All of the STAT mutant proteins were tyrosine phosphorylated by JAK2 and heterodimerized with STAT5B except for the WKR mutant, suggesting an important role for this region in STAT5 for stabilizing dimerization. The WKR, EE, and VVV mutants had no detectable DNA-binding activity, and the WKR and VVV mutants, but not EE, were defective in transcriptional induction. The VVV mutant had a moderate dominant negative effect on erythropoietin-induced STAT5 transcriptional activation, which was likely due to the formation of heterodimers that are defective in DNA binding. Interestingly, the WKR mutant had a potent dominant negative effect, comparable to the transactivation domain deletion mutant, ▵53C. Stable expression of either the WKR or ▵53C STAT5 mutants in the murine myeloid cytokine-dependent cell line 32D inhibited both interleukin-3–dependent proliferation and granulocyte colony-stimulating factor (G-CSF)–dependent differentiation, without induction of apoptosis. Expression of these mutants in primary murine bone marrow inhibited G-CSF–dependent granulocyte colony formation in vitro. These results demonstrate that mutations in distinct regions of STAT5 exert dominant negative effects on cytokine signaling, likely through different mechanisms, and suggest a role for STAT5 in proliferation and differentiation of myeloid cells.

The scavenging effect of curcumin, piperine and their combination against physiological relevant reactive pro-oxidant species using in vitro non-cellular and cellular models

2021 ◽  
Author(s):  
Mariana Lucas ◽  
Marisa Freitas ◽  
Jadriane A. Xavier ◽  
Fabiana A. Moura ◽  
Marília O. F. Goulart ◽  
...  
Keyword(s):  
Scavenging Effect ◽  
Cellular Models

scholarly journals Self-organization and culture of Mesenchymal Stem Cell spheroids in acoustic levitation

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Nathan Jeger-Madiot ◽  
Lousineh Arakelian ◽  
Niclas Setterblad ◽  
Patrick Bruneval ◽  
Mauricio Hoyos ◽  
...  
Keyword(s):  
Cell Culture ◽  
3D Cell Culture ◽  
Culture Conditions ◽  
Acoustic Levitation ◽  
Cell Sheets ◽  
Cell Therapies ◽  
Cellular Models ◽  
Cell Spheroids

AbstractIn recent years, 3D cell culture models such as spheroid or organoid technologies have known important developments. Many studies have shown that 3D cultures exhibit better biomimetic properties compared to 2D cultures. These properties are important for in-vitro modeling systems, as well as for in-vivo cell therapies and tissue engineering approaches. A reliable use of 3D cellular models still requires standardized protocols with well-controlled and reproducible parameters. To address this challenge, a robust and scaffold-free approach is proposed, which relies on multi-trap acoustic levitation. This technology is successfully applied to Mesenchymal Stem Cells (MSCs) maintained in acoustic levitation over a 24-h period. During the culture, MSCs spontaneously self-organized from cell sheets to cell spheroids with a characteristic time of about 10 h. Each acoustofluidic chip could contain up to 30 spheroids in acoustic levitation and four chips could be ran in parallel, leading to the production of 120 spheroids per experiment. Various biological characterizations showed that the cells inside the spheroids were viable, maintained the expression of their cell surface markers and had a higher differentiation capacity compared to standard 2D culture conditions. These results open the path to long-time cell culture in acoustic levitation of cell sheets or spheroids for any type of cells.

scholarly journals The Diagnostic Journey of a Patient with Prader–Willi-Like Syndrome and a Unique Homozygous SNURF-SNRPN Variant; Bio-Molecular Analysis and Review of the Literature

Genes ◽  
2021 ◽  
Vol 12 (6) ◽  
pp. 875
Author(s):  
Karlijn Pellikaan ◽  
Geeske M. van Woerden ◽  
Lotte Kleinendorst ◽  
Anna G. W. Rosenberg ◽  
Bernhard Horsthemke ◽  
...  
Keyword(s):  
Intellectual Disability ◽  
Single Nucleotide Polymorphism Array ◽  
Genetic Defect ◽  
Missense Variant ◽  
Dominant Negative ◽  
Dominant Negative Effect ◽  
Pituitary Hormone ◽  
Negative Effect

Prader–Willi syndrome (PWS) is a rare genetic condition characterized by hypotonia, intellectual disability, and hypothalamic dysfunction, causing pituitary hormone deficiencies and hyperphagia, ultimately leading to obesity. PWS is most often caused by the loss of expression of a cluster of genes on chromosome 15q11.2-13. Patients with Prader–Willi-like syndrome (PWLS) display features of the PWS phenotype without a classical PWS genetic defect. We describe a 46-year-old patient with PWLS, including hypotonia, intellectual disability, hyperphagia, and pituitary hormone deficiencies. Routine genetic tests for PWS were normal, but a homozygous missense variant NM_003097.3(SNRPN):c.193C>T, p.(Arg65Trp) was identified. Single nucleotide polymorphism array showed several large regions of homozygosity, caused by high-grade consanguinity between the parents. Our functional analysis, the ‘Pipeline for Rapid in silico, in vivo, in vitro Screening of Mutations’ (PRiSM) screen, showed that overexpression of SNRPN-p.Arg65Trp had a dominant negative effect, strongly suggesting pathogenicity. However, it could not be confirmed that the variant was responsible for the phenotype of the patient. In conclusion, we present a unique homozygous missense variant in SNURF-SNRPN in a patient with PWLS. We describe the diagnostic trajectory of this patient and the possible contributors to her phenotype in light of the current literature on the genotype–phenotype relationship in PWS.

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