Movement of Vesicles in Eucariotic Cells. Role of Intravesicle Protons as a Fuel and Modulation of Their Concentration by Drugs or Metabolic Changes.

AbstractImport (endocytosis) and export (secretion) of molecules from the cells is mediated by vesicles (lysosomes, endosomes) sliding along microtubules or actin filaments. These vesicles share a common feature: an internal pH of about 5, with an inner protons concentration 1000 fold higher than in the surrounding cytoplasm. As the proton gradient in mitochondria is able to drive ATP synthesis we can expect a similar role (energy supplier) for protons in all acidic vesicles. To experimentally test the vesicles' transport we have loaded them with a fluorescent dye (chloroquine) and then measured its efflux over 5 hours. This efflux was reduced by all treatments lowering the actual concentration of protons in the vesicles, independently of the properties. Treatments included lowering intracellular NADH, inhibitors of ATP-dependent proton translocase and/or the Na+/H+antiport, drugs that accumulate into lysosomes, buffering its acidity (chloroquine, doxorubicin). These results support the idea of a role of a proton gradient as a fuel for protein motors.

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Platelet Shape Changes during Thrombus Formation: Role of Actin-Based Protrusions

Hämostaseologie ◽

10.1055/a-1325-0993 ◽

2021 ◽

Vol 41 (01) ◽

pp. 014-021

Author(s):

Markus Bender ◽

Raghavendra Palankar

Keyword(s):

Blood Loss ◽

Actin Filaments ◽

Thrombus Formation ◽

Short Review ◽

Critical Component ◽

Clot Retraction ◽

Shape Changes ◽

Platelet Shape

AbstractPlatelet activation and aggregation are essential to limit blood loss at sites of vascular injury but may also lead to occlusion of diseased vessels. The platelet cytoskeleton is a critical component for proper hemostatic function. Platelets change their shape after activation and their contractile machinery mediates thrombus stabilization and clot retraction. In vitro studies have shown that platelets, which come into contact with proteins such as fibrinogen, spread and first form filopodia and then lamellipodia, the latter being plate-like protrusions with branched actin filaments. However, the role of platelet lamellipodia in hemostasis and thrombus formation has been unclear until recently. This short review will briefly summarize the recent findings on the contribution of the actin cytoskeleton and lamellipodial structures to platelet function.

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Mitochondrial microRNAs: A Putative Role in Tissue Regeneration

Biology ◽

10.3390/biology9120486 ◽

2020 ◽

Vol 9 (12) ◽

pp. 486

Author(s):

Sílvia C. Rodrigues ◽

Renato M. S. Cardoso ◽

Filipe V. Duarte

Keyword(s):

Tissue Regeneration ◽

Protein Complexes ◽

Mitochondrial Protein ◽

Noncoding Rnas ◽

Atp Synthesis ◽

Mitochondrial Proteins ◽

Cellular Mechanisms ◽

Small Noncoding Rnas ◽

Mitochondrial Ribosome

The most famous role of mitochondria is to generate ATP through oxidative phosphorylation, a metabolic pathway that involves a chain of four protein complexes (the electron transport chain, ETC) that generates a proton-motive force that in turn drives the ATP synthesis by the Complex V (ATP synthase). An impressive number of more than 1000 mitochondrial proteins have been discovered. Since mitochondrial proteins have a dual genetic origin, it is predicted that ~99% of these proteins are nuclear-encoded and are synthesized in the cytoplasmatic compartment, being further imported through mitochondrial membrane transporters. The lasting 1% of mitochondrial proteins are encoded by the mitochondrial genome and synthesized by the mitochondrial ribosome (mitoribosome). As a result, an appropriate regulation of mitochondrial protein synthesis is absolutely required to achieve and maintain normal mitochondrial function. Regarding miRNAs in mitochondria, it is well-recognized nowadays that several cellular mechanisms involving mitochondria are regulated by many genetic players that originate from either nuclear- or mitochondrial-encoded small noncoding RNAs (sncRNAs). Growing evidence collected from whole genome and transcriptome sequencing highlight the role of distinct members of this class, from short interfering RNAs (siRNAs) to miRNAs and long noncoding RNAs (lncRNAs). Some of the mechanisms that have been shown to be modulated are the expression of mitochondrial proteins itself, as well as the more complex coordination of mitochondrial structure and dynamics with its function. We devote particular attention to the role of mitochondrial miRNAs and to their role in the modulation of several molecular processes that could ultimately contribute to tissue regeneration accomplishment.

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Role of Hypoxia in Cerebral Circulatory and Metabolic Changes during Hypocarbia in Man: Studies in Hyperbaric Milieu

Scandinavian Journal of Clinical and Laboratory Investigation ◽

10.3109/00365516809168978 ◽

1968 ◽

Vol 21 (sup102) ◽

pp. IV-B-IV-B ◽

Cited By ~ 3

Author(s):

M. Reivich ◽

J. Dickson ◽

J. Clark ◽

M. Hedden ◽

C. J. Lambertsen

Keyword(s):

Metabolic Changes

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Applications of Metabolomics in Forensic Toxicology and Forensic Medicine

International Journal of Molecular Sciences ◽

10.3390/ijms22063010 ◽

2021 ◽

Vol 22 (6) ◽

pp. 3010

Author(s):

Michal Szeremeta ◽

Karolina Pietrowska ◽

Anna Niemcunowicz-Janica ◽

Adam Kretowski ◽

Michal Ciborowski

Keyword(s):

Machine Learning ◽

Multivariate Statistics ◽

High Throughput ◽

Forensic Medicine ◽

Forensic Toxicology ◽

Metabolic Changes ◽

Untargeted Metabolomics ◽

Criminal Cases ◽

Statistical Approaches

Forensic toxicology and forensic medicine are unique among all other medical fields because of their essential legal impact, especially in civil and criminal cases. New high-throughput technologies, borrowed from chemistry and physics, have proven that metabolomics, the youngest of the “omics sciences”, could be one of the most powerful tools for monitoring changes in forensic disciplines. Metabolomics is a particular method that allows for the measurement of metabolic changes in a multicellular system using two different approaches: targeted and untargeted. Targeted studies are focused on a known number of defined metabolites. Untargeted metabolomics aims to capture all metabolites present in a sample. Different statistical approaches (e.g., uni- or multivariate statistics, machine learning) can be applied to extract useful and important information in both cases. This review aims to describe the role of metabolomics in forensic toxicology and in forensic medicine.

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Ischemic preconditioning in rats: role of mitochondrial KATP channel in preservation of mitochondrial function

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.2000.278.1.h305 ◽

2000 ◽

Vol 278 (1) ◽

pp. H305-H312 ◽

Cited By ~ 128

Author(s):

Ryan M. Fryer ◽

Janis T. Eells ◽

Anna K. Hsu ◽

Michele M. Henry ◽

Garrett J. Gross

Keyword(s):

Infarct Size ◽

Ischemic Preconditioning ◽

Mitochondrial Function ◽

Ischemia Reperfusion ◽

Mitochondrial Protein ◽

Atp Synthesis ◽

Area At Risk ◽

Selective Antagonist ◽

Mitochondrial Katp Channel

We examined the role of the sarcolemmal and mitochondrial KATPchannels in a rat model of ischemic preconditioning (IPC). Infarct size was expressed as a percentage of the area at risk (IS/AAR). IPC significantly reduced infarct size (7 ± 1%) versus control (56 ± 1%). The sarcolemmal KATP channel-selective antagonist HMR-1098 administered before IPC did not significantly attenuate cardioprotection. However, pretreatment with the mitochondrial KATP channel-selective antagonist 5-hydroxydecanoic acid (5-HD) 5 min before IPC partially abolished cardioprotection (40 ± 1%). Diazoxide (10 mg/kg iv) also reduced IS/AAR (36.2 ± 4.8%), but this effect was abolished by 5-HD. As an index of mitochondrial bioenergetic function, the rate of ATP synthesis in the AAR was examined. Untreated animals synthesized ATP at 2.12 ± 0.30 μmol ⋅ min−1 ⋅ mg mitochondrial protein−1. Rats subjected to ischemia-reperfusion synthesized ATP at 0.67 ± 0.06 μmol ⋅ min−1 ⋅ mg mitochondrial protein−1. IPC significantly increased ATP synthesis to 1.86 ± 0.23 μmol ⋅ min−1 ⋅ mg mitochondrial protein−1. However, when 5-HD was administered before IPC, the preservation of ATP synthesis was attenuated (1.18 ± 0.15 μmol ⋅ min−1 ⋅ mg mitochondrial protein−1). These data are consistent with the notion that inhibition of mitochondrial KATPchannels attenuates IPC by reducing IPC-induced protection of mitochondrial function.

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Formation of smooth muscle α actin filaments in CD34+ bone marrow cells on arterial elastic laminae: Potential role of SH2 domain-containing protein tyrosine phosphatase-1

Matrix Biology ◽

10.1016/j.matbio.2008.01.001 ◽

2008 ◽

Vol 27 (4) ◽

pp. 282-294 ◽

Cited By ~ 4

Author(s):

S LIU ◽

B TEFFT ◽

A ZHANG ◽

L ZHANG ◽

Y WU

Keyword(s):

Bone Marrow ◽

Smooth Muscle ◽

Protein Tyrosine Phosphatase ◽

Actin Filaments ◽

Potential Role ◽

Bone Marrow Cells ◽

Tyrosine Phosphatase ◽

Sh2 Domain ◽

Elastic Laminae

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Role of metabolic changes of mucosal layer in the intestinal barrier dysfunction following trauma/hemorrhagic shock

Pathology - Research and Practice ◽

10.1016/j.prp.2018.08.023 ◽

2018 ◽

Vol 214 (11) ◽

pp. 1879-1884 ◽

Cited By ~ 2

Author(s):

Ran Zhu ◽

Xiao-chun Ma

Keyword(s):

Hemorrhagic Shock ◽

Intestinal Barrier ◽

Metabolic Changes ◽

Barrier Dysfunction ◽

Intestinal Barrier Dysfunction ◽

Mucosal Layer

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Microinjection of antibodies against talin inhibits the spreading and migration of fibroblasts

Journal of Cell Science ◽

10.1242/jcs.102.4.753 ◽

1992 ◽

Vol 102 (4) ◽

pp. 753-762

Author(s):

G.H. Nuckolls ◽

L.H. Romer ◽

K. Burridge

Keyword(s):

Extracellular Matrix ◽

Tissue Culture ◽

Actin Filaments ◽

Focal Adhesions ◽

Cell Spreading ◽

And Migration ◽

Extracellular Matrix Receptors

Talin is believed to be one of the key proteins involved in linking actin filaments to extracellular matrix receptors in focal adhesions. Our strategy for studying the function of talin has been to inactivate talin in living fibroblasts in tissue culture through the microinjection of affinity-purified, polyclonal anti-talin antibodies. The effect of the injected anti-talin antibodies on cell spreading was found to depend on how recently the cells had been plated. Cells that were in the process of spreading on a fibronectin substratum, and which had newly developed focal adhesions, were induced to round up and to disassemble many of the adhesions. However, if fibroblasts were allowed to spread completely before they were microinjected with the anti-talin antibody, focal adhesions remained intact and the flat morphology of the cells was unaffected. The percentage of cells that were able to maintain a spread morphology despite the injection of anti-talin antibodies increased during the first few hours after plating on fibronectin substrata. Fibroblasts that were allowed to spread completely before microinjection with the anti-talin antibody retained both intact focal adhesions and a flat, well-spread morphology, but failed to migrate effectively. Our experiments do not directly address the role of talin in mature focal adhesions, but they indicate that talin is essential for the spreading and migration of fibroblasts on fibronectin as well as for the development and initial maintenance of focal adhesions on this substratum.

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Dynamics of Tpm1.8 domains on actin filaments with single molecule resolution

10.1101/2020.06.15.152033 ◽

2020 ◽

Cited By ~ 1

Author(s):

Ilina Bareja ◽

Hugo Wioland ◽

Miro Janco ◽

Philip R. Nicovich ◽

Antoine Jégou ◽

...

Keyword(s):

Actin Filament ◽

Single Molecule ◽

Actin Filaments ◽

High Probability ◽

Actin Binding ◽

Single Molecule Level ◽

Filament Dynamics ◽

Kinetics Of ◽

Insight Into

ABSTRACTTropomyosins regulate dynamics and functions of the actin cytoskeleton by forming long chains along the two strands of actin filaments that act as gatekeepers for the binding of other actin-binding proteins. The fundamental molecular interactions underlying the binding of tropomyosin to actin are still poorly understood. Using microfluidics and fluorescence microscopy, we observed the binding of fluorescently labelled tropomyosin isoform Tpm1.8 to unlabelled actin filaments in real time. This approach in conjunction with mathematical modeling enabled us to quantify the nucleation, assembly and disassembly kinetics of Tpm1.8 on single filaments and at the single molecule level. Our analysis suggests that Tpm1.8 decorates the two strands of the actin filament independently. Nucleation of a growing tropomyosin domain proceeds with high probability as soon as the first Tpm1.8 molecule is stabilised by the addition of a second molecule, ultimately leading to full decoration of the actin filament. In addition, Tpm1.8 domains are asymmetrical, with enhanced dynamics at the edge oriented towards the barbed end of the actin filament. The complete description of Tpm1.8 kinetics on actin filaments presented here provides molecular insight into actin-tropomyosin filament formation and the role of tropomyosins in regulating actin filament dynamics.

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