scholarly journals Bringing the Ca 2+ sensitivity of myristoylated recoverin into the physiological range

Open Biology ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 200346
Author(s):  
Valerio Marino ◽  
Matteo Riva ◽  
Davide Zamboni ◽  
Karl-Wilhelm Koch ◽  
Daniele Dell'Orco
Keyword(s):  
Protein Complexes ◽  
Calcium Sensitivity ◽  
Sensory Transduction ◽  
Disc Membrane ◽  
Physiological Range ◽  
Intracellular Ca ◽  
Rhodopsin Kinase ◽  
Multiple Ligands ◽  
The Individual

The prototypical Ca 2+ -sensor protein recoverin (Rec) is thought to regulate the activity of rhodopsin kinase (GRK1) in photoreceptors by switching from a relaxed (R) disc membrane-bound conformation in the dark to a more compact, cytosol-diffusing tense (T) conformation upon cell illumination. However, the apparent affinity for Ca 2+ of its physiologically relevant form (myristoylated recoverin) is almost two orders of magnitude too low to support this mechanism in vivo . In this work, we compared the individual and synergistic roles of the myristic moiety, the GRK1 target and the disc membrane in modulating the calcium sensitivity of Rec. We show that the sole presence of the target or the disc membrane alone are not sufficient to achieve a physiological response to changes in intracellular [Ca 2+ ]. Instead, the simultaneous presence of GRK1 and membrane allows the T to R transition to occur in a physiological range of [Ca 2+ ] with high cooperativity via a conformational selection mechanism that drives the structural transitions of Rec in the presence of multiple ligands. Our conclusions may apply to other sensory transduction systems involving protein complexes and biological membranes.

scholarly journals Unraveling the mechanism of the cadherin-catenin-actin catch bond

2018 ◽  
Author(s):  
Shishir Adhikari ◽  
Jacob Moran ◽  
Christopher Weddle ◽  
Michael Hinczewski
Keyword(s):  
Protein Complexes ◽  
Optical Tweezer ◽  
Force Transducer ◽  
Salt Bridges ◽  
Lifetime Distributions ◽  
Catch Bond ◽  
The Individual ◽  
And Function

The adherens junctions between epithelial cells involve a protein complex formed by E-cadherin, β-catenin, α-catenin and F-actin. The stability of this complex was a puzzle for many years, since in vitro studies could reconstitute various stable subsets of the individual proteins, but never the entirety. The missing ingredient turned out to be mechanical tension: a recent experiment that applied physiological forces to the complex with an optical tweezer dramatically increased its lifetime, a phenomenon known as catch bonding. However, in the absence of a crystal structure for the full complex, the microscopic details of the catch bond mechanism remain mysterious. Building on structural clues that point to α-catenin as the force transducer, we present a quantitative theoretical model for how the catch bond arises, fully accounting for the experimental lifetime distributions. The model allows us to predict the energetic changes induced by tension at the interface between α-catenin and F-actin. It also identifies a significant energy barrier due to a network of salt bridges between two conformational states of β-catenin. By stabilizing one of these states, this barrier could play a role in how the complex responds to additional in vivo binding partners like vinculin. Since significant conformational energy barriers are a common feature of other adhesion systems that exhibit catch bonds, our model can be adapted into a general theoretical framework for integrating structure and function in a variety of force-regulated protein complexes.

Photoinhibition in vivo and in vitro Involves Weakly Coupled Chlorophyll–Protein Complexes‡¶

2002 ◽  
Vol 75 (6) ◽  
pp. 613 ◽  
Author(s):  
Stefano Santabarbara ◽  
Ilaria Cazzalini ◽  
Andrea Rivadossi ◽  
Flavio M. Garlaschi ◽  
Giuseppe Zucchelli ◽  
...  
Keyword(s):  
Protein Complexes ◽  
Weakly Coupled ◽  
Chlorophyll Protein Complexes ◽  
Chlorophyll Protein

scholarly journals RNA-Centric Approaches to Profile the RNA–Protein Interaction Landscape on Selected RNAs

2021 ◽  
Vol 7 (1) ◽  
pp. 11 ◽  
Author(s):  
André P. Gerber
Keyword(s):  
Mass Spectrometry ◽  
Protein Interactions ◽  
Regulatory Networks ◽  
Rna Binding ◽  
Rna Binding Proteins ◽  
Protein Complexes ◽  
Cell Protein ◽  
Transcriptional Regulatory Networks ◽  
Technological Advances

RNA–protein interactions frame post-transcriptional regulatory networks and modulate transcription and epigenetics. While the technological advances in RNA sequencing have significantly expanded the repertoire of RNAs, recently developed biochemical approaches combined with sensitive mass-spectrometry have revealed hundreds of previously unrecognized and potentially novel RNA-binding proteins. Nevertheless, a major challenge remains to understand how the thousands of RNA molecules and their interacting proteins assemble and control the fate of each individual RNA in a cell. Here, I review recent methodological advances to approach this problem through systematic identification of proteins that interact with particular RNAs in living cells. Thereby, a specific focus is given to in vivo approaches that involve crosslinking of RNA–protein interactions through ultraviolet irradiation or treatment of cells with chemicals, followed by capture of the RNA under study with antisense-oligonucleotides and identification of bound proteins with mass-spectrometry. Several recent studies defining interactomes of long non-coding RNAs, viral RNAs, as well as mRNAs are highlighted, and short reference is given to recent in-cell protein labeling techniques. These recent experimental improvements could open the door for broader applications and to study the remodeling of RNA–protein complexes upon different environmental cues and in disease.

scholarly journals Preclinical Testing of Radiopharmaceuticals for the Detection and Characterization of Osteomyelitis: Experiences from a Porcine Model

Molecules ◽  
2021 ◽  
Vol 26 (14) ◽  
pp. 4221
Author(s):  
Aage Kristian Olsen Alstrup ◽  
Svend Borup Jensen ◽  
Ole Lerberg Nielsen ◽  
Lars Jødal ◽  
Pia Afzelius
Keyword(s):  
Animal Model ◽  
Animal Models ◽  
Porcine Model ◽  
Animal Experiments ◽  
Radioactive Tracers ◽  
The Individual ◽  
Selection Of

The development of new and better radioactive tracers capable of detecting and characterizing osteomyelitis is an ongoing process, mainly because available tracers lack selectivity towards osteomyelitis. An integrated part of developing new tracers is the performance of in vivo tests using appropriate animal models. The available animal models for osteomyelitis are also far from ideal. Therefore, developing improved animal osteomyelitis models is as important as developing new radioactive tracers. We recently published a review on radioactive tracers. In this review, we only present and discuss osteomyelitis models. Three ethical aspects (3R) are essential when exposing experimental animals to infections. Thus, we should perform experiments in vitro rather than in vivo (Replacement), use as few animals as possible (Reduction), and impose as little pain on the animal as possible (Refinement). The gain for humans should by far exceed the disadvantages for the individual experimental animal. To this end, the translational value of animal experiments is crucial. We therefore need a robust and well-characterized animal model to evaluate new osteomyelitis tracers to be sure that unpredicted variation in the animal model does not lead to a misinterpretation of the tracer behavior. In this review, we focus on how the development of radioactive tracers relies heavily on the selection of a reliable animal model, and we base the discussions on our own experience with a porcine model.

scholarly journals Animal Models in the Evaluation of the Effectiveness of Phage Therapy for Infections Caused by Gram-Negative Bacteria from the ESKAPE Group and the Reliability of Its Use in Humans

2021 ◽  
Vol 9 (2) ◽  
pp. 206
Author(s):  
Martyna Cieślik ◽  
Natalia Bagińska ◽  
Andrzej Górski ◽  
Ewa Jończyk-Matysiak
Keyword(s):  
Animal Models ◽  
Phage Therapy ◽  
Animal Experiments ◽  
Species Group ◽  
Effectiveness Evaluation ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Enterobacter Species ◽  
The Individual

The authors emphasize how extremely important it is to highlight the role played by animal models in an attempt to determine possible phage interactions with the organism into which it was introduced as well as to determine the safety and effectiveness of phage therapy in vivo taking into account the individual conditions of a given organism and its physiology. Animal models in which phages are used make it possible, among other things, to evaluate the effective therapeutic dose and to choose the possible route of phage administration depending on the type of infection developed. These results cannot be applied in detail to the human body, but the knowledge gained from animal experiments is invaluable and very helpful. We would like to highlight how useful animal models may be for the possible effectiveness evaluation of phage therapy in the case of infections caused by gram-negative bacteria from the ESKAPE (Enterococcus faecium, Staphylococcus aureus, Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, Enterobacter species) group of pathogens. In this review, we focus specifically on the data from the last few years.

scholarly journals Graphene and Reproduction: A Love-Hate Relationship

Nanomaterials ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 547
Author(s):  
Marina Ramal-Sanchez ◽  
Antonella Fontana ◽  
Luca Valbonetti ◽  
Alessandra Ordinelli ◽  
Nicola Bernabò ◽  
...  
Keyword(s):  
Graphene Oxide ◽  
Reproductive Function ◽  
Scientometric Analysis ◽  
Potential Toxicity ◽  
Good Tool ◽  
Vitro Fertilization ◽  
Number Of Publications ◽  
The Individual

Since its discovery, graphene and its multiple derivatives have been extensively used in many fields and with different applications, even in biomedicine. Numerous efforts have been made to elucidate the potential toxicity derived from their use, giving rise to an adequate number of publications with varied results. On this basis, the study of the reproductive function constitutes a good tool to evaluate not only the toxic effects derived from the use of these materials directly on the individual, but also the potential toxicity passed on to the offspring. By providing a detailed scientometric analysis, the present review provides an updated overview gathering all the research studies focused on the use of graphene and graphene-based materials in the reproductive field, highlighting the consequences and effects reported to date from experiments performed in vivo and in vitro and in different animal species (from Archea to mammals). Special attention is given to the oxidized form of graphene, graphene oxide, which has been recently investigated for its ability to increase the in vitro fertilization outcomes. Thus, the potential use of graphene oxide against infertility is hypothesized here, probably by engineering the spermatozoa and thus manipulating them in a safer and more efficient way.

scholarly journals ANTI-INFLAMMATORY ACTIVITY OF CURCUMIN AND CAPSAICIN AUGMENTED IN COMBINATION

2017 ◽  
Vol 9 (6) ◽  
pp. 145
Author(s):  
Thriveni Vasanth Kumar ◽  
Manjunatha H. ◽  
Rajesh Kp
Keyword(s):  
Acetic Acid ◽  
Protective Effect ◽  
Vascular Permeability ◽  
Diclofenac Sodium ◽  
Significant Inhibition ◽  
Inflammatory Activity ◽  
Anti Inflammatory ◽  
The Individual

Objective: Dietary curcumin and capsaicin are well known for their health beneficial potencies. The current study was done to assess the anti-inflammatory activity of curcumin, capsaicin and their combination by employing in vitro and in vivo models.Methods: We investigated the protective effect of curcumin, capsaicin and their combination using in vitro heat induced human red blood cell (HRBC) membrane stabilisation, in vivo 3% agar induced leukocyte mobilisation and acetic acid induced vascular permeability assay.Results: Curcumin, capsaicin and their combination exhibited concentration dependent protective effect against heat-induced HRBC membrane destabilisation, while combined curcumin and capsaicin restored 87.0±0.64 % membrane stability and it is found to be better than curcumin, capsaicin and diclofenac sodium (75.0±0.25. 72±0.9 and 80.0±0.31 %) protective effect. In agar suspension induced leukocyte mobilization assay, the combined curcumin and capsaicin had shown 39.5±1.58 % of inhibition compared to individual curcumin and capsaicin, which showed moderate inhibition of 16.0±3.14 and 21.6±2.17 % respectively. Besides, the combined curcumin and capsaicin had shown highly significant inhibition of acetic acid-induced vascular permeability in rats (62.0±3.14 %), whereas individual curcumin and capsaicin showed moderate inhibition of vascular permeability with 36.0±2.41 and 43.0±1.92 % respectively.Conclusion: This study demonstrates the significant anti-inflammatory property of combined curcumin and capsaicin at half of the individual concentration of curcumin and capsaicin.

Conformational Flexibility in Assembly of Photosynthetic Membrane Protein Complexes in vivo

2004 ◽  
Vol 10 (S02) ◽  
pp. 1496-1497
Author(s):  
P A Bullough
Keyword(s):  
Membrane Protein ◽  
Protein Complexes ◽  
Conformational Flexibility ◽  
Photosynthetic Membrane ◽  
Membrane Protein Complexes

Extended abstract of a paper presented at Microscopy and Microanalysis 2004 in Savannah, Georgia, USA, August 1–5, 2004.

Paradoxical effect of salbutamol in a model of acute organophosphates intoxication in guinea pigs: role of substance P release

2007 ◽  
Vol 292 (4) ◽  
pp. L915-L923 ◽  
Author(s):  
Jaime Chávez ◽  
Patricia Segura ◽  
Mario H. Vargas ◽  
José Luis Arreola ◽  
Edgar Flores-Soto ◽  
...  
Keyword(s):  
Substance P ◽  
Guinea Pigs ◽  
Smooth Muscle Contraction ◽  
In Vivo Experiments ◽  
Intracellular Ca ◽  
Neurokinin 1 ◽  
Substance P Release

Organophosphates induce bronchoobstruction in guinea pigs, and salbutamol only transiently reverses this effect, suggesting that it triggers additional obstructive mechanisms. To further explore this phenomenon, in vivo (barometric plethysmography) and in vitro (organ baths, including ACh and substance P concentration measurement by HPLC and immunoassay, respectively; intracellular Ca2+ measurement in single myocytes) experiments were performed. In in vivo experiments, parathion caused a progressive bronchoobstruction until a plateau was reached. Administration of salbutamol during this plateau decreased bronchoobstruction up to 22% in the first 5 min, but thereafter airway obstruction rose again as to reach the same intensity as before salbutamol. Aminophylline caused a sustained decrement (71%) of the parathion-induced bronchoobstruction. In in vitro studies, paraoxon produced a sustained contraction of tracheal rings, which was fully blocked by atropine but not by TTX, ω-conotoxin (CTX), or epithelium removal. During the paraoxon-induced contraction, salbutamol caused a temporary relaxation of ∼50%, followed by a partial recontraction. This paradoxical recontraction was avoided by the M2- or neurokinin-1 (NK1)-receptor antagonists (methoctramine or AF-DX 116, and L-732138, respectively), accompanied by a long-lasting relaxation. Forskolin caused full relaxation of the paraoxon response. Substance P and, to a lesser extent, ACh released from tracheal rings during 60-min incubation with paraoxon or physostigmine, respectively, were significantly increased when salbutamol was administered in the second half of this period. In myocytes, paraoxon did not produce any change in the intracellular Ca2+ basal levels. Our results suggested that: 1) organophosphates caused smooth muscle contraction by accumulation of ACh released through a TTX- and CTX-resistant mechanism; 2) during such contraction, salbutamol relaxation is functionally antagonized by the stimulation of M2 receptors; and 3) after this transient salbutamol-induced relaxation, a paradoxical contraction ensues due to the subsequent release of substance P.

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