VDAC function in a cellular context

2004 ◽  
pp. 251-266
Author(s):  
Michael Forte
Keyword(s):  
Cellular Context

scholarly journals Split NanoLuc technology allows quantitation of interactions between PII protein and its receptors with unprecedented sensitivity and reveals transient interactions

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Rokhsareh Rozbeh ◽  
Karl Forchhammer
Keyword(s):  
The Novel ◽  
Multiple Target ◽  
Interacting Protein ◽  
Effector Molecule ◽  
Target Proteins ◽  
Pii Protein ◽  
Protein X ◽  
Cellular Context ◽  
Pii Proteins ◽  
Transient Interactions

AbstractPII proteins constitute a widespread signal transduction superfamily in the prokaryotic world. The canonical PII signal proteins sense metabolic state of the cells by binding the metabolite molecules ATP, ADP and 2-oxoglutarate. Depending on bound effector molecule, PII proteins interact with and modulate the activity of multiple target proteins. To investigate the complexity of interactions of PII with target proteins, analytical methods that do not disrupt the native cellular context are required. To this purpose, split luciferase proteins have been used to develop a novel complementation reporter called NanoLuc Binary Technology (NanoBiT). The luciferase NanoLuc is divided in two subunits: a 18 kDa polypeptide termed “Large BiT” and a 1.3 kDa peptide termed “Small BiT”, which only weakly associate. When fused to proteins of interest, they reconstitute an active luciferase when the proteins of interest interact. Therefore, we set out to develop a new NanoBiT sensor based on the interaction of PII protein from Synechocystis sp. PCC6803 with PII-interacting protein X (PipX) and N-acetyl-L-glutamate kinase (NAGK). The novel NanoBiT sensor showed unprecedented sensitivity, which made it possible to detect even weak and transient interactions between PII variants and their interacting partners, thereby shedding new light in PII signalling processes.

scholarly journals Biosensors Monitor Ligand-Selective Effects at Kappa Opioid Receptors

2021 ◽  
Author(s):  
Lucie Oberhauser ◽  
Miriam Stoeber
Keyword(s):  
Subcellular Location ◽  
Receptor Activation ◽  
Cellular Level ◽  
Two Dimensions ◽  
Kappa Opioid Receptor ◽  
Kappa Opioid ◽  
Downstream Signaling ◽  
Regulator Protein ◽  
Cellular Context ◽  
Selective Effects

AbstractThe kappa opioid receptor (KOR) has emerged as a promising therapeutic target for pain and itch treatment. There is growing interest in biased agonists that preferentially activate select signaling pathways downstream of KOR activation on the cellular level due to their therapeutic promise in retaining the analgesic and antipruritic effects and eliminating the sedative and dysphoric effects of KOR signaling on the physiological level. The concept of ligand-selective signaling includes that biased ligands promote KOR to selectively recruit one transducer or regulator protein over another, introducing bias into the signaling cascade at the very receptor-proximal level. Measuring agonist effects directly at the receptor has remained challenging and previous studies have focused on inferring agonist-selective KOR engagement with G protein relative to β-arrestin based on downstream signaling readouts. Here we discuss novel strategies to directly assess ligand-selective effects on receptor activation using KOR-interacting biosensors. The conformation-specific cytoplasmic biosensors are disconnected from the endogenous signaling machinery and provide a direct receptor-proxy readout of ligand effects in living cells. Receptor–biosensor interaction is ligand concentration dependent and can be used to determine relative ligand potency and efficacy. In addition, the biosensors reveal the existence of two dimensions of agonist bias in the cellular context: Firstly, agonists can selectively produce discrete protein-engaged KOR states and secondly, agonists can differ in the precise subcellular location at which they activate KOR. We discuss the value and the limitations of using orthogonal receptor-interacting biosensors in the quest to understand functional selectivity amongst KOR agonists in the cellular context.

scholarly journals The Hallmarks of Flavonoids in Cancer

Molecules ◽  
2021 ◽  
Vol 26 (7) ◽  
pp. 2029
Author(s):  
Luis Gustavo Saboia Ponte ◽  
Isadora Carolina Betim Pavan ◽  
Mariana Camargo Silva Mancini ◽  
Luiz Guilherme Salvino da Silva ◽  
Ana Paula Morelli ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Cell Proliferation ◽  
Biological Activity ◽  
Neurological Disorders ◽  
Mechanisms Of Action ◽  
Molecular Signaling ◽  
Hallmarks Of Cancer ◽  
Redox Metabolism ◽  
Important Group ◽  
Cellular Context

Flavonoids represent an important group of bioactive compounds derived from plant-based foods and beverages with known biological activity in cells. From the modulation of inflammation to the inhibition of cell proliferation, flavonoids have been described as important therapeutic adjuvants against several diseases, including diabetes, arteriosclerosis, neurological disorders, and cancer. Cancer is a complex and multifactor disease that has been studied for years however, its prevention is still one of the best known and efficient factors impacting the epidemiology of the disease. In the molecular and cellular context, some of the mechanisms underlying the oncogenesis and the progression of the disease are understood, known as the hallmarks of cancer. In this text, we review important molecular signaling pathways, including inflammation, immunity, redox metabolism, cell growth, autophagy, apoptosis, and cell cycle, and analyze the known mechanisms of action of flavonoids in cancer. The current literature provides enough evidence supporting that flavonoids may be important adjuvants in cancer therapy, highlighting the importance of healthy and balanced diets to prevent the onset and progression of the disease.

scholarly journals Nrf2/Keap1-Pathway Activation and Reduced Susceptibility to Chemotherapy Treatment by Acidification in Esophageal Adenocarcinoma Cells

Cancers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 2806
Author(s):  
Lucie Storz ◽  
Philipp Walther ◽  
Olga Chemnitzer ◽  
Orestis Lyros ◽  
Stefan Niebisch ◽  
...  
Keyword(s):  
Esophageal Adenocarcinoma ◽  
Squamous Epithelium ◽  
Acid Reflux ◽  
Cellular Damage ◽  
Pathway Activation ◽  
Cellular Context ◽  
Vitro Model ◽  
Nfκb Pathway ◽  
Eac Cells

Chronic acid reflux causes cellular damage and inflammation in the lower esophagus. Due to these irritating insults, the squamous epithelium is replaced by metaplastic epithelium, which is a risk factor for the development of esophageal adenocarcinoma (EAC). In this study, we investigated the acid susceptibility in a Barrett’s cell culture in vitro model, using six cell lines, derived from squamous epithelium (EPC1 and EPC2), metaplasia (CP-A), dysplasia (CP-B), and EAC (OE33 and OE19) cells. Cells exposed to acidic pH showed a decreased viability dependent on time, pH, and progression status in the Barrett’s sequence, with the highest acid susceptibility in the squamous epithelium (EPC1 and EPC2), and the lowest in EAC cells. Acid pulsing was accompanied with an activation of the Nrf2/Keap1- and the NFκB-pathway, resulting in an increased expression of HO1—independent of the cellular context. OE33 showed a decreased responsiveness towards 5-FU, when the cells were grown in acidic conditions (pH 6 and pH 5.5). Our findings suggest a strong damage of squamous epithelium by gastroesophageal reflux, while Barrett’s dysplasia and EAC cells apparently exert acid-protective features, which lead to a cellular resistance against acid reflux.

scholarly journals Avoided motifs: short amino acid strings missing from protein datasets

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Pablo Mier ◽  
Miguel A. Andrade-Navarro
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Protein Function ◽  
Large Protein ◽  
New Approach ◽  
Cellular Context ◽  
Human Proteins ◽  
Context Specific ◽  
Protein Datasets

Abstract According to the amino acid composition of natural proteins, it could be expected that all possible sequences of three or four amino acids will occur at least once in large protein datasets purely by chance. However, in some species or cellular context, specific short amino acid motifs are missing due to unknown reasons. We describe these as Avoided Motifs, short amino acid combinations missing from biological sequences. Here we identify 209 human and 154 bacterial Avoided Motifs of length four amino acids, and discuss their possible functionality according to their presence in other species. Furthermore, we determine two Avoided Motifs of length three amino acids in human proteins specifically located in the cytoplasm, and two more in secreted proteins. Our results support the hypothesis that the characterization of Avoided Motifs in particular contexts can provide us with information about functional motifs, pointing to a new approach in the use of molecular sequences for the discovery of protein function.

scholarly journals Cyclovirobuxine D Induced-Mitophagy through the p65/BNIP3/LC3 Axis Potentiates Its Apoptosis-Inducing Effects in Lung Cancer Cells

2021 ◽  
Vol 22 (11) ◽  
pp. 5820
Author(s):  
Cheng Zeng ◽  
Tingting Zou ◽  
Junyan Qu ◽  
Xu Chen ◽  
Suping Zhang ◽  
...  
Keyword(s):  
Lung Cancer ◽  
Cancer Cells ◽  
Transcriptional Repression ◽  
Therapeutic Strategy ◽  
Ectopic Expression ◽  
Lung Cancer Cells ◽  
Lung Cancer Patients ◽  
Cellular Context ◽  
Subcutaneous Xenograft ◽  
Buxus Microphylla

Mitophagy plays a pro-survival or pro-death role that is cellular-context- and stress-condition-dependent. In this study, we revealed that cyclovirobuxine D (CVB-D), a natural compound derived from Buxus microphylla, was able to provoke mitophagy in lung cancer cells. CVB-D-induced mitophagy potentiates apoptosis by promoting mitochondrial dysfunction. Mechanistically, CVB-D initiates mitophagy by enhancing the expression of the mitophagy receptor BNIP3 and strengthening its interaction with LC3 to provoke mitophagy. Our results further showed that p65, a transcriptional suppressor of BNIP3, is downregulated upon CVB-D treatment. The ectopic expression of p65 inhibits BNIP3 expression, while its knockdown significantly abolishes its transcriptional repression on BNIP3 upon CVB-D treatment. Importantly, nude mice bearing subcutaneous xenograft tumors presented retarded growth upon CVB-D treatment. Overall, we demonstrated that CVB-D treatment can provoke mitophagy and further revealed that the p65/BNIP3/LC3 axis is one potential mechanism involved in CVB-D-induced mitophagy in lung cancer cells, thus providing an effective antitumor therapeutic strategy for the treatment of lung cancer patients

scholarly journals Friend or Foe: Paradoxical Roles of Autophagy in Gliomagenesis

Cells ◽  
2021 ◽  
Vol 10 (6) ◽  
pp. 1411
Author(s):  
Don Carlo Ramos Batara ◽  
Moon-Chang Choi ◽  
Hyeon-Uk Shin ◽  
Hyunggee Kim ◽  
Sung-Hak Kim
Keyword(s):  
Brain Tumor ◽  
Glioblastoma Multiforme ◽  
Cancer Biology ◽  
Molecular Mechanisms ◽  
Primary Brain Tumor ◽  
Molecular Target ◽  
Therapeutic Strategies ◽  
Homeostatic Mechanism ◽  
Cellular Context ◽  
Cellular Components

Glioblastoma multiforme (GBM) is the most common and aggressive type of primary brain tumor in adults, with a poor median survival of approximately 15 months after diagnosis. Despite several decades of intensive research on its cancer biology, treatment for GBM remains a challenge. Autophagy, a fundamental homeostatic mechanism, is responsible for degrading and recycling damaged or defective cellular components. It plays a paradoxical role in GBM by either promoting or suppressing tumor growth depending on the cellular context. A thorough understanding of autophagy’s pleiotropic roles is needed to develop potential therapeutic strategies for GBM. In this paper, we discussed molecular mechanisms and biphasic functions of autophagy in gliomagenesis. We also provided a summary of treatments for GBM, emphasizing the importance of autophagy as a promising molecular target for treating GBM.

Contribution of Sex and Cellular Context in the Regulation of Brain Corticosteroid Receptors following Restraint Stress

2000 ◽  
Vol 71 (6) ◽  
pp. 343-353 ◽  
Author(s):  
Despoina Karandrea ◽  
Christos Kittas ◽  
Efthimia Kitraki
Keyword(s):  
Restraint Stress ◽  
Corticosteroid Receptors ◽  
Cellular Context

scholarly journals Structural elements in the flexible tail of the co-chaperone p23 coordinate client binding and progression of the Hsp90 chaperone cycle

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Maximilian M. Biebl ◽  
Abraham Lopez ◽  
Alexandra Rehn ◽  
Lee Freiburger ◽  
Jannis Lawatscheck ◽  
...  
Keyword(s):  
Proximal Region ◽  
Tryptophan Residue ◽  
Structural Elements ◽  
Physiological Importance ◽  
In Vivo Experiments ◽  
Cellular Context ◽  
Catalytic Loop ◽  
Hsp90 Chaperone

AbstractThe co-chaperone p23 is a central part of the Hsp90 machinery. It stabilizes the closed conformation of Hsp90, inhibits its ATPase and is important for client maturation. Yet, how this is achieved has remained enigmatic. Here, we show that a tryptophan residue in the proximal region of the tail decelerates the ATPase by allosterically switching the conformation of the catalytic loop in Hsp90. We further show by NMR spectroscopy that the tail interacts with the Hsp90 client binding site via a conserved helix. This helical motif in the p23 tail also binds to the client protein glucocorticoid receptor (GR) in the free and Hsp90-bound form. In vivo experiments confirm the physiological importance of ATPase modulation and the role of the evolutionary conserved helical motif for GR activation in the cellular context.

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