Publications by authors named "Lukasz Majewski"

21 Publications

  • Page 1 of 1

Modern Biodegradable Plastics-Processing and Properties Part II.

Materials (Basel) 2021 May 12;14(10). Epub 2021 May 12.

Department of Polymer Chemistry, Faculty of Chemistry, Institute of Chemical Sciences, Maria Curie-Skłodowska University in Lublin, ul. Gliniana 33, 20-614 Lublin, Poland.

Four different plastics were tested: potato starch based plastic (TPS-P)-BIOPLAST GF 106/02; corn starch based plastic (TPS-C)-BioComp BF 01HP; polylactic acid (polylactide) plastic (PLA)-BioComp BF 7210 and low density polyethylene, trade name Malen E FABS 23-D022; as a petrochemical reference sample. Using the blown film extrusion method and various screw rotational speeds, films were obtained and tested, as a result of which the following were determined: breaking stress, strain at break, static and dynamic friction coefficient of film in longitudinal and transverse direction, puncture resistance and strain at break, color, brightness and gloss of film, surface roughness, barrier properties and microstructure. The biodegradable plastics tested are characterized by comparable or even better mechanical strength than petrochemical polyethylene for the range of film blowing processing parameters used here. The effect of the screw rotational speed on the mechanical characteristics of the films obtained was also demonstrated. With the increase in the screw rotational speed, the decrease of barrier properties was also observed. No correlation between roughness and permeability of gases and water vapor was shown. It was indicated that biodegradable plastics might be competitive for conventional petrochemical materials used in film blowing niche applications where cost, recyclability, optical and water vapor barrier properties are not critical.
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http://dx.doi.org/10.3390/ma14102523DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8152069PMC
May 2021

-Deficient Zebrafish Reproduce Neurological and Inflammatory Symptoms of Niemann-Pick Type C Disease.

Front Cell Neurosci 2021 27;15:647860. Epub 2021 Apr 27.

Laboratory of Neurodegeneration, International Institute of Molecular and Cell Biology in Warsaw, Warsaw, Poland.

Niemann-Pick type C (NPC) disease is an autosomal recessive lysosomal storage disease that is caused by a mutation of the or gene, in which un-esterified cholesterol and sphingolipids accumulate mainly in the liver, spleen, and brain. Abnormal lysosomal storage leads to cell damage, neurological problems, and premature death. The time of onset and severity of symptoms of NPC disease are highly variable. The molecular mechanisms that are responsible for NPC disease pathology are far from being understood. The present study generated and characterized a zebrafish mutant that lacks Npc2 protein that may be useful for studies at the organismal, cellular, and molecular levels and both small-scale and high-throughput screens. Using CRISPR/Cas9 technology, we knocked out the zebrafish homolog of . Five-day-old mutants were morphologically indistinguishable from wildtype larvae. We found that live larvae exhibited stronger Nile blue staining. The larvae exhibited low mobility and a high anxiety-related response. These behavioral changes correlated with downregulation of the (mitochondrial calcium uniporter) gene, (calcineurin) gene, and genes that are involved in myelination ( and ). Histological analysis of adult zebrafish revealed that pathological changes in the nervous system, kidney, liver, and pancreas correlated with inflammatory responses (i.e., the upregulation of , κβ, and ; i.e., hallmarks of NPC disease). These findings suggest that the mutant zebrafish may be a model of NPC disease.
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http://dx.doi.org/10.3389/fncel.2021.647860DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8111220PMC
April 2021

Efficiency of Twin-Screw Extrusion of Biodegradable Poly (Butylene Succinate)-Wheat Bran Blend.

Materials (Basel) 2021 Jan 16;14(2). Epub 2021 Jan 16.

Department of Polymer Chemistry, Institute of Chemical Sciences, Faculty of Chemistry, Maria Curie-Sklodowska University, 20-614 Lublin, Poland.

Unmodified poly (butylene succinate) (PBS) is characterized by very good processability; however, after the incorporation of various fillers of plant origin, its processing becomes much more complicated and its properties are significantly affected. Detailed studies of the processing aspects of PBS/wheat bran (WB) biocomposition are lacking, despite the addition of WB having a significant impact on both the production efficiency and the properties of end products. This research paper presents test results of the co-rotating twin-screw extrusion processing of a biodegradable polymer blend, the matrix of which was PBS, with WB as the filler. In undertaking this task, we examined the impact of extruder screw rotational speed and WB content on the characteristics of extrusion processing, as well as on certain thermal, physical, structural and processing properties of the obtained blend. The WB introduced to the blend was in the form of a selected fraction with particles smaller than 0.2 mm. The measurements were conducted using the Design of Experiment (DOE) methods, which enabled establishing the studied relationships in the form of polynomials and response surfaces. The determined extrusion process characteristics covered the impact of screw rotational speed and WB content on the mass flow rate of the processed blend and its pressure, the screw drive torque and specific energy consumption. The studies of the obtained polymer blend included determining the impact of the aforementioned variable factors on the melt flow rate (MFR) index, chemical structure (FTIR), thermal properties (differential scanning calorimetry (DSC), thermogravimetry (TG), derivative thermogravimetry (DTG)), relationships, microstructure, density and moisture absorbance. Analysis of variance (ANOVA) was used to assess the effect of individual variable factors. The results of this work are presented, inter alia, using Pareto charts of standardized effects, which illustrate the influence of individual terms of the determined regression equations on the studied quantity.
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http://dx.doi.org/10.3390/ma14020424DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7829807PMC
January 2021

Analysis of Selected Properties of Biocomposites Based on Polyethylene with a Natural Origin Filler.

Materials (Basel) 2020 Sep 20;13(18). Epub 2020 Sep 20.

Department of Polymer Chemistry, Institute of Chemical Sciences, Faculty of Chemistry, Maria Curie-Sklodowska University in Lublin, 33 Gliniana Street, 20-614 Lublin, Poland.

The study investigates the effect of the content and size of wheat bran grains on selected properties of a lignocellulosic biocomposite on a polyethylene matrix. The biocomposite samples were made by injection method of low-density polyethylene with 5%, 10% and 15% by weight of wheat bran. Three bran fractions with grain sizes <0.4 mm, 0.4-0.6 mm and 0.6-0.8 mm were used. The properties of the mouldings (after primary shrinkage) were examined after their 2.5-year natural aging period. Processing properties, such as MFR (mass flow rate) and processing shrinkage, were determined. Selected physical, mechanical and structural properties of the produced biocomposite samples were tested. The results allowed the determination of the influence of both the content of bran and the size of its grains on such properties of the biocomposite as: color, gloss, processing shrinkage, tensile strength, MFR mass flow rate, chemical structure (FTIR), thermal properties (DSC, TG), p-v-T relationship. The tests did not show any deterioration of the mechanical characteristics of the tested composites after natural aging.
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http://dx.doi.org/10.3390/ma13184182DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7560486PMC
September 2020

Modern Biodegradable Plastics-Processing and Properties: Part I.

Materials (Basel) 2020 Apr 24;13(8). Epub 2020 Apr 24.

Department of Polymer Chemistry, Institute of Chemical Sciences, Faculty of Chemistry, Maria Curie-Sklodowska University in Lublin, ul. Gliniana 33, 20-614 Lublin, Poland.

This paper presents a characterization of a plastic extrusion process and the selected properties of three biodegradable plastic types, in comparison with LDPE (low-density polyethylene). The four plastics include: LDPE, commercial name Malen E FABS 23-D022; potato starch based plastic (TPS-P), BIOPLAST GF 106/02; corn starch based plastic (TPS-C), BioCompBF 01HP; and a polylactic acid (polylactide) plastic (PLA), BioCompBF 7210. Plastic films with determined geometric parameters (thickness of the foil layer and width of the flattened foil sleeve) were produced from these materials (at individually defined processing temperatures), using blown film extrusion, by applying different extrusion screw speeds. The produced plastic films were tested to determine the geometrical features, MFR (melt flow rate), blow-up ratio, draw down ratio, mass flow rate, and exit velocity. The tests were complemented by thermogravimetry, differential scanning calorimetry, and chemical structure analysis. It was found that the biodegradable films were extruded at higher rate and mass flow rate than LDPE; the lowest thermal stability was ascertained for the film samples extruded from TPS-C and TPS-P, and that all tested biodegradable plastics contained polyethylene.
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http://dx.doi.org/10.3390/ma13081986DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7215468PMC
April 2020

Transgenic Mice Overexpressing Human and in Neurons Exhibit Changes in Behavior and Calcium Homeostasis but Show No Signs of Neurodegeneration.

Int J Mol Sci 2020 Jan 28;21(3). Epub 2020 Jan 28.

International Institute of Molecular and Cell Biology in Warsaw, 4 Ksiecia Trojdena Str., 02-109 Warsaw, Poland.

The maintenance of proper cytosolic Ca level is crucial for neuronal survival, and dysregulation of Ca homeostasis is found in a variety of neurological disorders, including Alzheimer's disease. According to the "Ca hypothesis of aging", Ca disturbances precede the onset of AD symptoms and lead to neurodegeneration. STIM and ORAI proteins are involved in neuronal physiological and pathological processes as essential components of the store-operated Ca entry. Our previous data suggested that overexpression of and might increase basal neuronal cytosolic Ca level. We generated double transgenic mice overexpressing these two genes in neurons, expecting that the increased basal Ca concentration will lead to premature neurodegeneration. We observed changes in Ca homeostasis and electrophysiological properties in acute brain slices of STIM2/ORAI1 neurons. However, we did not observe any augmentation of neurodegenerative processes, as tested by Fluoro-Jade C staining and assessment of amyloidogenesis. The battery of behavioral tests did not show any signs of accelerated aging. We conclude that changes of calcium homeostasis induced by overexpression of and had no substantial adverse effects on neurons and did not lead to early neurodegeneration.
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http://dx.doi.org/10.3390/ijms21030842DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7037127PMC
January 2020

STIM Protein-NMDA2 Receptor Interaction Decreases NMDA-Dependent Calcium Levels in Cortical Neurons.

Cells 2020 01 9;9(1). Epub 2020 Jan 9.

Laboratory of Neurodegeneration, International Institute of Molecular and Cell Biology in Warsaw, 02-109 Warsaw, Poland.

Neuronal Store-Operated Ca Entry (nSOCE) plays an essential role in refilling endoplasmic reticulum Ca stores and is critical for Ca-dependent neuronal processes. SOCE sensors, STIM1 and STIM2, can activate Orai, TRP channels and AMPA receptors, and inhibit voltage-gated channels in the plasma membrane. However, the link between STIM, SOCE, and NMDA receptors, another key cellular entry point for Ca contributing to synaptic plasticity and excitotoxicity, remains unclear. Using Ca imaging, we demonstrated that thapsigargin-induced nSOCE was inhibited in rat cortical neurons following NMDAR inhibitors. Blocking nSOCE by its inhibitor SKF96365 enhanced NMDA-driven [Ca]. Modulating STIM protein level through overexpression or shRNA inhibited or activated NMDA-evoked [Ca], respectively. Using proximity ligation assays, immunofluorescence, and co-immunoprecipitation methods, we discovered that thapsigargin-dependent effects required interactions between STIMs and the NMDAR2 subunits. Since STIMs modulate NMDAR-mediated Ca levels, we propose targeting this mechanism as a novel therapeutic strategy against neuropathological conditions that feature NMDA-induced Ca overload as a diagnostic criterion.
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http://dx.doi.org/10.3390/cells9010160DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7017226PMC
January 2020

Influence of the Design Solutions of Extruder Screw Mixing Tip on Selected Properties of Wheat Bran-Polyethylene Biocomposite.

Polymers (Basel) 2019 Dec 17;11(12). Epub 2019 Dec 17.

Department of Polymer Chemistry, Institute of Chemical Science, Faculty of Chemistry, Maria Curie-Sklodowska University, 20-614 Lublin, Poland.

The study investigated the impact of the extruder screw design solution-the intensive mixing tip used-on the course of the extrusion process and the properties of the obtained biocomposite extrudate. A lignocellulosic wheat bran biocomposite based on a low-density polyethylene matrix was extruded. Three mixing tips of the screw were used interchangeably: apineapple tip, a cut rings tip, and a Maddock tip. The experimental tests carried out included the production of an extrudate with a mass content of bran altered within the range from 10% to 50%. Processing properties such as the melt flow rate (MFR) and mass flow rate of the extruded biocomposite were determined. Selected physical, mechanical, and structural properties of the biocomposite extrudate obtained with the use of the three tested mixing tips at five bran contents were tested.
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http://dx.doi.org/10.3390/polym11122120DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6960559PMC
December 2019

Changes in Calcium Homeostasis and Gene Expression Implicated in Epilepsy in Hippocampi of Mice Overexpressing .

Int J Mol Sci 2019 Nov 6;20(22). Epub 2019 Nov 6.

Laboratory of Neurodegeneration, International Institute of Molecular and Cell Biology in Warsaw, Trojdena 4, 02-109 Warsaw, Poland.

Previously, we showed that the overexpression of calcium channel in neurons of murine brain led to spontaneous occurrence of seizure-like events in aged animals of transgenic line FVB/NJ-Tg(ORAI1)Ibd (Nencki Institute of Experimental Biology). We aimed to identify the mechanism that is responsible for this phenomenon. Using a modified Ca-addback assay in the CA1 region of acute hippocampal slices and FURA-2 acetomethyl ester (AM) Ca indicator, we found that overexpression of in neurons led to altered Ca response. Next, by RNA sequencing (RNAseq) we identified a set of genes, whose expression was changed in our transgenic animals. These data were validated using customized real-time PCR assays and digital droplet PCR (ddPCR) ddPCR. Using real-time PCR, up-regulation of hairy and enhancer of split-5 ( gene and down-regulation of aristaless related homeobox , doublecortin-like kinase 1 ( and cyclin-dependent kinase-like 5 (, also known as serine/threonine kinase 9 (Stk9)) genes were found. Digital droplet PCR (ddPCR) analysis revealed down-regulation of . In humans, , and were shown to be mutated in some rare epilepsy-associated disorders. We conclude that the occurrence of seizure-like events in aged mice overexpressing might be due to the down-regulation of and possibly of 5 and genes.
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http://dx.doi.org/10.3390/ijms20225539DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6888010PMC
November 2019

Influence of the Conditions of Corotating Twin-Screw Extrusion for Talc-Filled Polypropylene on Selected Properties of the Extrudate.

Polymers (Basel) 2019 Sep 6;11(9). Epub 2019 Sep 6.

Department of Polymer Chemistry, Faculty of Chemistry, Maria Curie-Sklodowska University, 20-614 Lublin, Poland.

The aim of the study was to determine the effect of the application of processing screws with a modified test segment in a corotating twin-screw extruder on selected properties of talc-filled polypropylene extrudate. The test segment was built of trilobe kneading elements and its design modifications refered to changing the distance between the kneading elements and the angle of positions of kneading elements that are relative to each other. The performed tests included the production of extrudate with various degrees of talc-filling using five design solutions of the test segment and then measurements of selected properties, such as tensile strength, elongation at maximum tensile stress, and melt flow rate. Structural studies using scanning electron microscope (SEM) and differential scanning calorimetry (DSC) were also carried out. The study includes not only the description of experimental results but also the determination of empirical models describing the dependence of the properties of the obtained extrudate on the conditions of the extrusion process and the design features of the test segment.
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http://dx.doi.org/10.3390/polym11091460DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6781200PMC
September 2019

Behavioral and electrophysiological changes in female mice overexpressing ORAI1 in neurons.

Biochim Biophys Acta Mol Cell Res 2019 07 16;1866(7):1137-1150. Epub 2019 Jan 16.

International Institute of Molecular and Cell Biology in Warsaw, 4 Ks. Trojdena Str., Warsaw 02-109, Poland.

Orai proteins form highly selective Ca release-activated channels (CRACs). They play a critical role in store-operated Ca entry (SOCE; i.e., the influx of external Ca that is induced by the depletion of endoplasmic reticulum Ca stores). Of the three Orai homologs that are present in mammals (Orai1-3), the physiological function of Orai1 is the best described. CRACs are formed by both homomeric assemblies and heteromultimers of Orais. Orai1 and Orai2 can form heteromeric channels that differ in conductivity during SOCE, depending on their Orai1-to-Orai2 ratio. The present study explored the potential consequences of ORAI1 overexpression in neurons where the dominant isoform is Orai2. We established the Tg(ORAI1)Ibd transgenic mouse line that overexpresses ORAI1 in brain neurons. We observed seizure-like symptoms in aged (≥15-month-old) female mice but not in males of the same age. The application of kainic acid and bicuculline to slices that were isolated from 8-month-old (±1 month) female Tg(ORAI1)Ibd mice revealed a significantly lower frequency of interictal bursts compared with samples that were isolated from wildtype mice. No differences were observed in male mice of a similar age. A battery of behavioral tests showed that context recognition decreased only in female transgenic mice. The phenotype that was observed in female mice suggests that ORAI1 overexpression may affect neuronal activity in a sex-dependent manner. This article is part of a Special Issue entitled: ECS Meeting edited by Claus Heizmann, Joachim Krebs and Jacques Haiech.
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http://dx.doi.org/10.1016/j.bbamcr.2019.01.007DOI Listing
July 2019

Myosin VI in the nucleus of neurosecretory PC12 cells: Stimulation-dependent nuclear translocation and interaction with nuclear proteins.

Nucleus 2018 01;9(1):125-141

a Laboratory of Molecular Basis of Cell Motility , Department of Biochemistry, Nencki Institute of Experimental Biology, Polish Academy of Sciences , Warsaw , Poland.

Myosin VI (MVI) is a unique actin-based motor protein moving towards the minus end of actin filaments, in the opposite direction than other known myosins. Besides well described functions of MVI in endocytosis and maintenance of Golgi apparatus, there are few reports showing its involvement in transcription. We previously demonstrated that in neurosecretory PC12 cells MVI was present in the cytoplasm and nucleus, and its depletion caused substantial inhibition of cell migration and proliferation. Here, we show an increase in nuclear localization of MVI upon cell stimulation, and identification of potential nuclear localization (NLS) and nuclear export (NES) signals within MVI heavy chain. These signals seem to be functional as the MVI nuclear presence was affected by the inhibitors of nuclear import (ivermectin) and export (leptomycin B). In nuclei of stimulated cells, MVI colocalized with active RNA polymerase II, BrUTP-containing transcription sites and transcription factor SP1 as well as SC35 and PML proteins, markers of nuclear speckles and PML bodies, respectively. Mass spectrometry analysis of samples of a GST-pull-down assay with the MVI tail domain as a "bait" identified several new potential MVI binding partners. Among them are proteins involved in transcription and post-transcriptional processes. We confirmed interaction of MVI with heterogeneous nuclear ribonucleoprotein U (hnRNPU) and nucleolin, proteins involved in pre-mRNA binding and transport, and nucleolar function, respectively. Our data provide an insight into mechanisms of involvement of MVI in nuclear processes via interaction with nuclear proteins and support a notion for important role(s) for MVI in gene expression.
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http://dx.doi.org/10.1080/19491034.2017.1421881DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5973263PMC
January 2018

Overexpression of STIM1 in neurons in mouse brain improves contextual learning and impairs long-term depression.

Biochim Biophys Acta Mol Cell Res 2017 Jun 29;1864(6):1071-1087. Epub 2016 Nov 29.

International Institute of Molecular and Cell Biology in Warsaw, 4 Ks. Trojdena Str., 02-109 Warsaw, Poland. Electronic address:

STIM1 is an endoplasmic reticulum calcium sensor that is involved in several processes in neurons, including store-operated calcium entry. STIM1 also inhibits voltage-gated calcium channels, such as Ca1.2 and Ca3.1, and is thus considered a multifunctional protein. The aim of this work was to investigate the ways in which transgenic neuronal overexpression of STIM1 in FVB/NJ mice affects animal behavior and the electrophysiological properties of neurons in acute hippocampal slices. We overexpressed STIM1 from the Thy1.2 promoter and verified neuronal expression by quantitative reverse-transcription polymerase chain reaction, Western blot, and immunohistochemistry. Mature primary hippocampal cultures expressed STIM1 but exhibited no changes in calcium homeostasis. Basal synaptic transmission efficiency and short-term plasticity were comparable in slices that were isolated from transgenic mice, similarly as the magnitude of long-term potentiation. However, long-term depression that was induced by the glutamate receptor 1/5 agonist (S)-3,5-dihydroxyphenylglycine was impaired in STIM1 slices. Interestingly, transgenic mice exhibited a decrease in anxiety-like behavior and improvements in contextual learning. In summary, our data indicate that STIM1 overexpression in neurons in the brain perturbs metabotropic glutamate receptor signaling, leading to impairments in long-term depression and alterations in animal behavior. This article is part of a Special Issue entitled: ECS Meeting edited by Claus Heizmann, Joachim Krebs and Jacques Haiech.
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http://dx.doi.org/10.1016/j.bbamcr.2016.11.025DOI Listing
June 2017

Interaction of myosin VI and its binding partner DOCK7 plays an important role in NGF-stimulated protrusion formation in PC12 cells.

Biochim Biophys Acta 2016 Jul 25;1863(7 Pt A):1589-600. Epub 2016 Mar 25.

Laboratory of Molecular Basis of Cell Motility, Department of Biochemistry, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093 Warsaw, Poland. Electronic address:

DOCK7 (dedicator of cytokinesis 7) is a guanidine nucleotide exchange factor (GEF) for Rac1 GTPase that is involved in neuronal polarity and axon generation as well in Schwann cell differentiation and myelination. Recently, we identified DOCK7 as the binding partner of unconventional myosin VI (MVI) in neuronal-lineage PC12 cells and postulated that this interaction could be important in vivo [Majewski et al. (2012) Biochem Cell Biol., 90:565-574]. Herein, we found that MVI-DOCK7 interaction takes also place in other cell lines and demonstrated that MVI cargo domain via its RRL motif binds to DOCK7 C-terminal M2 and DHR2 domains. In MVI knockdown cells, lower Rac1 activity and a decrease of DOCK7 phosphorylation on Tyr1118 were observed, indicating that MVI could contribute to DOCK7 activity. MVI and DOCK7 co-localization was maintained during NGF-stimulated PC12 cell differentiation and observed also in the outgrowths. Also, during differentiation an increase in phosphorylation of DOCK7 as well as of its downstream effector JNK kinase was detected. Interestingly, overexpression of GFP-tagged MVI cargo domain (GFP-GT) impaired protrusion formation indicating that full length protein is important for this process. Moreover, a transient increase in Rac activity observed at 5min of NGF-stimulated differentiation of PC12 cells (overexpressing either GFP or GFP-MVI) was not detected in cells overexpressing the cargo domain. These data indicate that MVI-DOCK7 interaction could have functional implications in the protrusion outgrowth, and full length MVI seems to be important for delivery and maintenance of DOCK7 along the protrusions, and exerting its GEF activity.
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http://dx.doi.org/10.1016/j.bbamcr.2016.03.020DOI Listing
July 2016

Involvement of unconventional myosin VI in myoblast function and myotube formation.

Histochem Cell Biol 2015 Jul 21;144(1):21-38. Epub 2015 Apr 21.

Department of Biochemistry, Nencki Institute of Experimental Biology, 3 Pasteur St., 02-093, Warsaw, Poland.

The important role of unconventional myosin VI (MVI) in skeletal and cardiac muscle has been recently postulated (Karolczak et al. in Histochem Cell Biol 139:873-885, 2013). Here, we addressed for the first time a role for this unique myosin motor in myogenic cells as well as during their differentiation into myotubes. During myoblast differentiation, the isoform expression pattern of MVI and its subcellular localization underwent changes. In undifferentiated myoblasts, MVI-stained puncti were seen throughout the cytoplasm and were in close proximity to actin filaments, Golgi apparatus, vinculin-, and talin-rich focal adhesion as well as endoplasmic reticulum. Colocalization of MVI with endoplasmic reticulum was enhanced during myotube formation, and differentiation-dependent association was also seen in sarcoplasmic reticulum of neonatal rat cardiomyocytes (NRCs). Moreover, we observed enrichment of MVI in myotube regions containing acetylcholine receptor-rich clusters, suggesting its involvement in the organization of the muscle postsynaptic machinery. Overexpression of the H246R MVI mutant (associated with hypertrophic cardiomyopathy) in myoblasts and NRCs caused the formation of abnormally large intracellular vesicles. MVI knockdown caused changes in myoblast morphology and inhibition of their migration. On the subcellular level, MVI-depleted myoblasts exhibited aberrations in the organization of actin cytoskeleton and adhesive structures as well as in integrity of Golgi apparatus and endoplasmic reticulum. Also, MVI depletion or overexpression of H246R mutant caused the formation of significantly wider or aberrant myotubes, respectively, indicative of involvement of MVI in myoblast differentiation. The presented results suggest an important role for MVI in myogenic cells and possibly in myoblast differentiation.
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http://dx.doi.org/10.1007/s00418-015-1322-6DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4469105PMC
July 2015

SOCE in neurons: Signaling or just refilling?

Biochim Biophys Acta 2015 Sep 31;1853(9):1940-52. Epub 2015 Jan 31.

International Institute of Molecular and Cell Biology in Warsaw, Trojdena 4, 02-109 Warsaw, Poland. Electronic address:

In this review we describe the present knowledge about store operated Ca²⁺ entry (SOCE) in neurons and the proteins involved in this process: STIM, as well as Orai and TRP channels. We address the issue of whether SOCE is used only to refill Ca²⁺ in the ER or whether Ca²⁺ that enters the neuronal cell during SOCE also performs signaling functions. We collected the data indicating that SOCE and its components participate in the important processes in neurons. This has implications for identifying new drug targets for the treatment of brain diseases. Evidence indicates that in neurodegenerative diseases Ca²⁺ homeostasis and SOCE components become dysregulated. Thus, different targets and strategies might be identified for the potential treatment of these diseases. This article is part of a Special Issue entitled: 13th European symposium on calcium.
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http://dx.doi.org/10.1016/j.bbamcr.2015.01.019DOI Listing
September 2015

Myosin VI in skeletal muscle: its localization in the sarcoplasmic reticulum, neuromuscular junction and muscle nuclei.

Histochem Cell Biol 2013 Jun 30;139(6):873-85. Epub 2012 Dec 30.

Department of Biochemistry, Nencki Institute of Experimental Biology, 3 Pasteur St. 02-093, Warsaw, Poland.

Myosin VI (MVI) is a unique unconventional motor moving backwards on actin filaments. In non-muscle cells, it is involved in cell migration, endocytosis and intracellular trafficking, actin cytoskeleton dynamics, and possibly in gene transcription. An important role for MVI in striated muscle functioning was suggested in a report showing that a point mutation (H236R) within the MVI gene was associated with cardiomyopathy (Mohiddin et al., J Med Genet 41:309-314, 2004). Here, we have addressed MVI function in striated muscle by examining its expression and distribution in rat hindlimb skeletal muscle. We found that MVI was present predominantly at the muscle fiber periphery, and it was also localized within muscle nuclei. Analysis of both the hindlimb and cardiac muscle longitudinal sections revealed ~3 μm striation pattern, corresponding to the sarcoplasmic reticulum. Moreover, MVI was detected in the sarcoplasmic reticulum fractions isolated from skeletal and cardiac muscle. The protein also localized to the postsynaptic region of the neuromuscular junction. In denervated muscle, the defined MVI distribution pattern was abolished and accompanied by significant increase in its amount in the muscle fibers. In addition, we have identified several novel potential MVI-binding partners, which seem to aid our observations that in striated muscle MVI could be involved in postsynaptic trafficking as well as in maintenance of and/or transport within the sarcoplasmic reticulum and non-sarcomeric cytoskeleton.
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http://dx.doi.org/10.1007/s00418-012-1070-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3656228PMC
June 2013

Dock7: a GEF for Rho-family GTPases and a novel myosin VI-binding partner in neuronal PC12 cells.

Biochem Cell Biol 2012 Aug 4;90(4):565-74. Epub 2012 Apr 4.

Laboratory of Molecular Basis of Cell Motility, Department of Biochemistry, Nencki Institute of Experimental Biology, 3 Pasteur St, 02-093 Warsaw, Poland.

Myosin VI (MVI), the only known myosin that walks towards the minus end of actin filaments, is involved in several processes such as endocytosis, cell migration, and cytokinesis. It may act as a transporting motor or a protein engaged in actin cytoskeleton remodelling via its binding partners, interacting with its C-terminal globular tail domain. By means of pull-down technique and mass spectrometry, we identified Dock7 (dedicator of cytokinesis 7) as a potential novel MVI-binding partner in neurosecretory PC12 cells. Dock7, expressed mainly in neuronal cells, is a guanine nucleotide exchange factor (GEF) for small GTPases, Rac1 and Cdc42, which are the major regulators of actin cytoskeleton. MVI-Dock7 interaction was further confirmed by co-immunoprecipitation of endogenous MVI complexed with Dock7. In addition, MVI and Dock7 colocalized in interphase and dividing cells. We conclude that in PC12 cells MVI-Dock7 complexes may function at different cellular locations during the entire cell cycle. Of note, MVI and Dock7 colocalized in primary culture hippocampal neurons also, predominantly in the outgrowths. We hypothesize that this newly identified interaction between MVI and Dock7 may help explain a mechanism for MVI-dependent regulation of actin cytoskeleton organization.
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http://dx.doi.org/10.1139/o2012-009DOI Listing
August 2012

Myosin VI in PC12 cells plays important roles in cell migration and proliferation but not in catecholamine secretion.

J Muscle Res Cell Motil 2011 Dec 22;32(4-5):291-302. Epub 2011 Nov 22.

Department of Biochemistry, Nencki Institute of Experimental Biology, 3 Pasteur Street, 02-093, Warsaw, Poland.

Myosin VI (MVI) is the only known myosin walking towards minus end of actin filaments and is believed to play distinct role(s) than other myosins. We addressed a role of this unique motor in secretory PC12 cells, derived from rat adrenal medulla pheochromocytoma using cell lines with reduced MVI synthesis (produced by means of siRNA). Decrease of MVI expression caused severe changes in cell size and morphology, and profound defects in actin cytoskeleton organization and Golgi structure. Also, significant inhibition of cell migration as well as cell proliferation was observed. Flow cytometric analysis revealed that MVI-deficient cells were arrested in G0/G1 phase of the cell cycle but did not undergo increased senescence as compared with control cells. Also, neither polyploidy nor aneuploidy were detected. Surprisingly, no significant effect on noradrenaline secretion was observed. These data indicate that in PC12 cells MVI is involved in cell migration and proliferation but is not crucial for stimulation-dependent catecholamine release.
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http://dx.doi.org/10.1007/s10974-011-9279-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3230755PMC
December 2011

Myosin VI is associated with secretory granules and is present in the nucleus in adrenal medulla chromaffin cells.

Acta Biochim Pol 2010 2;57(1):109-14. Epub 2010 Mar 2.

Department of Biochemistry, Nencki Institute of Experimental Biology, Warszawa, Poland.

Myosin VI (MVI) is the only known myosin walking towards minus end of actin filaments. Here, MVI, but not myosins IB or IIB, was detected in chromaffin granules isolated from bovine medulla and found to be tightly associated with the granule apical surface. MVI also localized to secretory granules within rat pheochromocytoma PC12 cells as well as to the Golgi apparatus, endoplasmic reticulum and clathrin-coated pits. Notably, it was also found in the nucleus. RT-PCR revealed that MVI splice variants with a large insert (LI), characteristic of polarized cells, were barely detectable in PC12 cells, whereas variants with a small insert (SI) were the major isoforms. The presented data indicate that MVI in adrenal medulla cells is engaged in secretory vesicle trafficking within the cytoplasm and possibly also involved in transport within the nucleus.
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June 2010

[Myosins in nucleus].

Postepy Biochem 2009 ;55(2):239-46

Pracownia Molekularnych Podstaw Ruchów Komórkowych, Zakład Biochemii, Instytut Biologii Doświadczalnej im. M. Nenckiego PAN, Warszawa.

Myosins, actin-dependent molecular motors are expressed in almost all eukaryotic cells where are engaged in a panoply of cellular processes such as muscle contraction, cell migration and adhesion, intracellular trafficking, cytokinesis, endocytosis and secretion. In recent years a number of reports has been published revealing nuclear localization of myosins as well as actin and actin-binding proteins. Namely, nuclear form of myosin IC (NMI), myosin VI, myosin XVIB and myosin XVIIIB were found in nucleus. NMI and myosin VI seem to be involved in gene transcription and possibly intranuclear transport. In this paper, current knowledge on the role of myosin motors in nucleus has been presented.
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November 2009