Miklos Nyitrai - Academia.edu (original) (raw)

Papers by Miklos Nyitrai

Journal of Muscle Research and Cell Motility, Feb 1, 2006

The EMBO Journal, Jan 14, 2004

Biochemical Journal, Jul 1, 2002

Az OTKA K60968 pályázat keretei között az eredeti terveinknek megfelelően tanulmányoztuk az aktin... more Az OTKA K60968 pályázat keretei között az eredeti terveinknek megfelelően tanulmányoztuk az aktin monomereknek és filamentumoknak más fehérjékkel és peptidekkel való kölcsönhatásait. A kutatások során elsősorban fluoreszcencia spektroszkópiai módszereket alkalmaztunk, de az adott kérdéskörtől függően ezen módszerek eredményeit kiegészítettük elektron paramágneses rezonancia spektroszkópiai és kalorimetriai vizsgálatokkal is. Részletes vizsgálatokban jellemeztük az aktin filamentumoknak a forminokkal való kölcsönhatását, és megállapítottuk, hogy a forminok kötődésével a filamentumok szerkezete lazábbá válik. Azt is megfigyeltük, hogy a forminok által kiváltott konformációs módosulásokat a tropomiozin vagy a miozin kötődése megszünteti. Tanulmányoztunk és leírtunk továbbá egy eddig nem jellemzett formin családot, a DAAM forminokat. Ezen vizsgálataink mellett jellemeztük és értelmeztük az aktinnak a kölcsönhatását egyes mérgező toxinokkal, valamint új megfigyeléseket tettünk az aktin-m...

(A) Emission spectra of IAEDANS (D, donor) in the absence and presence of IAF (A, accept... more (A) Emission spectra of IAEDANS (D, donor) in the absence and presence of IAF (A, acceptor), and in the absence and presence of Lmod2FL. The actin filament concentration was 4 μM. Note the acceptor induced decrease in the donor emission due to FRET. (B) Temperature-dependent FRET measurements were performed on IAEDENS-IAF actin filaments (4 μM) in the absence and presence of different concentrations of Lmod2FL. FRET efficiencies calculated from the emission spectra (representative spectra are shown on panel (A)) were normalised by FRET efficiency measured at the lowest temperature (relative f ‘, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0186288#pone.0186288.e009" target="_blank">Eq 9</a>) and plotted as a function of temperature. Data obtained in the absence (filled circles) or presence (empty circles) of Lmod2FL (5 μM) are shown. Data are presented as mean ± SD (n = 3).</p

(A) Bioinformatics analysis of Lmod protein sequences predicts intrinsically unstructure... more (A) Bioinformatics analysis of Lmod protein sequences predicts intrinsically unstructured protein regions. The disorder probability in Homo sapiens Lmod2 and Rattus norvegicus Lmod2 (Uniprot accession numbers are <a href="http://www.uniprot.org/uniprot/Q6P5Q4" target="_blank">Q6P5Q4</a> and <a href="http://www.uniprot.org/uniprot/A1A5Q0" target="_blank">A1A5Q0</a>, respectively). The analysis was performed by IUPred [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0186288#pone.0186288.ref042" target="_blank">42</a>, <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0186288#pone.0186288.ref043" target="_blank">43</a>]. The tryptophan residues of Rattus norvegicus Lmod2 are highlighted by red. (B) Structural features of the interactions of Tmod1 with actin. The complex between Tmod1 ABS1 and actin is shown (PDB ID: 4PKG). The position of W73 of Rattus norvegicus cardiac leiomodin2 is predicted by multiple sequence alignment and highlighted by red. (C) Structural features of the interactions of Lmod2 with actin. The complexes between Lmod2 ABS2/LRR or WH2 actin binding sites and actin monomers are shown (PDB ID: 4PKG). The position of W386 and W347 (red) of Rattus norvegicus cardiac leiomodin2 are predicted to localize in a flexible protein region (blue) by multiple sequence alignment (PDB ID: 4RWT). This flexible region between residues 339–388 is missing from the structure of 4RWT. (D) Tryptophan fluorescence spectra of Lmod2. Excitation (EX) and emission (EM) spectra of the intrinsic tryptophans of Lmod2FL (1 μM, black line) and Cterm (4 μM, grey line) were obtained at emission wavelength of 354 nm and excitation wavelength of 282 nm.</p

(A) Effects of cardiac Lmod2 and Cterm on the polymerisation kinetics of actin. The kine... more (A) Effects of cardiac Lmod2 and Cterm on the polymerisation kinetics of actin. The kinetics of actin assembly (4 μM, containing 5% pyrene labelled actin) in the absence and presence of different concentrations of Lmod2FL or Cterm. Pyrene fluorescence was measured at excitation and emission wavelengths of 350 nm and 404 nm, respectively. Salt conditions: 100 mM KCl, 2 mM MgCl2. (B) Cardiac Lmod2 influences actin polymerisation in a concentration dependent manner. Polymerisation rates were determined from the slope of the pyrene curves (shown on panel (A)) at 50% polymerisation and normalised by the rate measured for spontaneous actin assembly. The actin polymerisation rates are plotted as a function of Lmod2FL (empty circles) and Cterm (filled circles) concentrations. (C) Ionic strength dependence of the effects of cardiac Lmod2 and Cterm on actin polymerisation. Pyrene-actin (4 μM, 5% labelled) was polymerised in the absence or presence of 100 nM Lmod2FL (empty circles) or 4 μM Cterm (filled circles) under low (10 mM KCl, 0.5 mM MgCl2), medium (50 mM KCl, 1 mM MgCl2) and high (100 mM KCl, 2 mM MgCl2) salt conditions. Normalised polymerisation rates were derived as described above and plotted as a function of ionic strength (<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0186288#pone.0186288.e004" target="_blank">Eq 4</a>). (D) The effect of cardiac Lmod2 on the critical concentration of actin assembly. Pyrene intensities as a function of actin concentration were measured in the absence (black circles) or presence of 100 nM Lmod2FL (grey circles) or 4 μM Cterm (light grey circles) under high salt conditions (100 mM KCl, 2 mM MgCl2). Actin (5% pyrene labelled) concentrations were 30; 50; 100; 300; 500; 700 nM and 1; 3; 5 μM. The critical concentrations were determined by using <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0186288#pone.0186288.e005" target="_blank">Eq 5</a> and were found to be 120 ± 83 nM in the absence of Lmod2FL and 117 ± 68 nM and 132 ± 58 nM in the presence of Lmod2FL and Cterm, respectively. Dashed lines in the corresponding colour show the fit to the data. (E) Skeletal tropomyosin (Tpm1.1/2.2) reduces the polymerisation activity of Lmod2. Pyrene-actin (4 μM, 5% labelled) was polymerised in the absence (empty squares) or presence (empty circles) of 1 μM Lmod2FL or 4 μM Cterm (filled circles) under high salt conditions (100 mM KCl, 2 mM MgCl2) in the presence of different concentrations of skeletal muscle tropomyosin. Data are presented as mean ± SD (n = 3).</p

Scientific Reports, 2020

An amendment to this paper has been published and can be accessed via a link at the top of the pa... more An amendment to this paper has been published and can be accessed via a link at the top of the paper.

PLoS ONE, 2013

The majority of lung cancers (LC) belong to the non-small cell lung carcinoma (NSCLC) type. The t... more The majority of lung cancers (LC) belong to the non-small cell lung carcinoma (NSCLC) type. The two main NSCLC sub-types, namely adenocarcinoma (AC) and squamous cell carcinoma (SCC), respond differently to therapy. Whereas the link between cigarette smoke and lung cancer risk is well established, the relevance of non-canonical Wnt pathway up-regulation detected in SCC remains poorly understood. The present study was undertaken to investigate further the molecular events in canonical and non-canonical Wnt signalling during SCC development. A total of 20 SCC and AC samples with matched non-cancerous controls were obtained after surgery. TaqMan array analysis confirmed up-regulation of non-canonical Wnt5a and Wnt11 and identified down-regulation of canonical Wnt signalling in SCC samples. The molecular changes were tested in primary small airway epithelial cells (SAEC) and various lung cancer cell lines (e.g. A549, H157, etc). Our studies identified Wnt11 and Wnt5a as regulators of cadherin expression and potentiated relocation of b-catenin to the nucleus as an important step in decreased cellular adhesion. The presented data identifies additional details in the regulation of SCC that can aid identification of therapeutic drug targets in the future.

(A) Polymerisation kinetics of actin assembly (4 μM; 5% labelled) in the presence of Lmo... more (A) Polymerisation kinetics of actin assembly (4 μM; 5% labelled) in the presence of Lmod2FL show increased saturation of pyrene fluorescence emission in a concentration dependent manner. (B) Cterm does not affect the steady-state value of pyrene actin fluorescence. The actin concentration was 4 μM, containing 5% labelled actin. (C) Rapid kinetics measurements of the time dependent change in pyrene F-actin fluorescence. Stopped-flow measurements of the kinetics of pyrene fluorescence emission of prepolymerised F-actin (1 μM, 5% pyrene labelled) in the absence or presence of different concentrations of Lmod2FL (1 μM, 6 μM and 12.5 μM, as indicated). Salt conditions: 100 mM KCl, 2 mM MgCl2. Dashed lines show the fit using <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0186288#pone.0186288.e007" target="_blank">Eq 7</a>.</p

Biophysical Journal, 2022

Supplementary material for manuscript entitled: "Detailed thermal characterization of ABS an... more Supplementary material for manuscript entitled: "Detailed thermal characterization of ABS and PLA based carbon composites used in additive manufacturing"

Polymers

Currently, 3D printing is an affordable technology for industry, healthcare, and individuals. Und... more Currently, 3D printing is an affordable technology for industry, healthcare, and individuals. Understanding the mechanical properties and thermoplastic behaviour of the composites is critical for the users. Our results give guidance for certain target groups including professionals in the field of additive manufacturing for biomedical components with in-depth characterisation of the examined commercially available ABS and PLA carbon-based composites. The study aimed to characterize these materials in terms of thermal behaviour and structure. The result of the heating-cooling loops is the thermal hysteresis effect of Ohmic resistance with its accommodation property in the temperature range of 20–84 °C for ESD-ABS and 20–72 °C for ESD-PLA. DSC-TGA measurements showed that the carbon content of the examined ESD samples is ~10–20% (m/m) and there is no significant difference in the thermodynamic behaviour of the basic ABS/PLA samples and their ESD compounds within the temperature range ...

Crystals

Additive manufacturing technologies are dynamically developing, strongly affecting almost all fie... more Additive manufacturing technologies are dynamically developing, strongly affecting almost all fields of industry and medicine. The appearance of electrically conductive polymers has had a great impact on the prototyping process of different electrical components in the case of upper limb prosthetic development. The widely used FFF 3D printing technology mainly uses PLA (polylactic acid) and ABS (acrylonitrile butadiene styrene) based composites, and despite their presence in the field, a detailed, critical characterization and comparison of them has not been performed yet. Our aim was to characterize two PLA and ABS based carbon composites in terms of electrical and mechanical behavior, and extend the observations with a structural and signal transfer analysis. The measurements were carried out by changing the different printing parameters, including layer resolution, printing orientation and infill density. To determine the mechanical properties, static and dynamic tests were condu...

Materials & Design

Abstract Spasticity is an important factor limiting independency and activity of daily living for... more Abstract Spasticity is an important factor limiting independency and activity of daily living for post-stroke patients. Our aim was to develop a cost effective, customized, lightweight active orthosis, which is convenient for daily home use. The study describes the steps of the development by using cutting edge technologies, as 3D printing for the frame of the device and nitinol smart memory alloy as the active part of the orthosis. Polyamide and thermoplastic polyurethane materials were characterized in terms of mechanical behaviour in different ambient conditions. To access the feasibility of the orthosis 6 voluntary post-stroke patients were asked to test the functionality with manual function test, daily living functionality tests and Likert scale. Movement analysis was used to evaluate the range of movement in the orthosis. The results showed significantly higher functionality by using the orthosis on manual function test, most of the daily functional tests, also the overall personal impressions accessed by Likert scale were positive. The new anti-spastic orthosis is a smart, active, lightweight, personalized device, which seems to be effective help for post-stroke patients to overcome spasticity. According to the initial data it is suitable for home use, therefore offers a convenient solution for advanced rehabilitation.

Scientific Reports

Here, we measured the concentrations of several ions in cultivated Gram-negative and Gram-positiv... more Here, we measured the concentrations of several ions in cultivated Gram-negative and Gram-positive bacteria, and analyzed their effects on polymer formation by the actin homologue MreB. We measured potassium, sodium, chloride, calcium and magnesium ion concentrations in Leptospira interrogans, Bacillus subtilis and Escherichia coli. Intracellular ionic strength contributed from these ions varied within the 130–273 mM range. The intracellular sodium ion concentration range was between 122 and 296 mM and the potassium ion concentration range was 5 and 38 mM. However, the levels were significantly influenced by extracellular ion levels. L. interrogans, Rickettsia rickettsii and E. coli MreBs were heterologously expressed and purified from E. coli using a novel filtration method to prepare MreB polymers. The structures and stability of Alexa-488 labeled MreB polymers, under varying ionic strength conditions, were investigated by confocal microscopy and MreB polymerization rates were ass...

Cells

The most prevalent Ca2+-buffer proteins (CaBPs: parvalbumin—PV; calbindin—CaB; calretinin—CaR) ar... more The most prevalent Ca2+-buffer proteins (CaBPs: parvalbumin—PV; calbindin—CaB; calretinin—CaR) are widely expressed by various neurons throughout the brain, including the retinal ganglion cells (RGCs). Even though their retinal expression has been extensively studied, a coherent assessment of topographical variations is missing. To examine this, we performed immunohistochemistry (IHC) in mouse retinas. We found variability in the expression levels and cell numbers for CaR, with stronger and more numerous labels in the dorso-central area. CaBP+ cells contributed to RGCs with all soma sizes, indicating heterogeneity. We separated four to nine RGC clusters in each area based on expression levels and soma sizes. Besides the overall high variety in cluster number and size, the peripheral half of the temporal retina showed the greatest cluster number, indicating a better separation of RGC subtypes there. Multiple labels showed that 39% of the RGCs showed positivity for a single CaBP, 30% ...

Scientific Reports

Blue Light Using Flavin (BLUF) domains are increasingly being adopted for use in optogenetic cons... more Blue Light Using Flavin (BLUF) domains are increasingly being adopted for use in optogenetic constructs. Despite this, much remains to be resolved on the mechanism of their activation. The advent of unnatural amino acid mutagenesis opens up a new toolbox for the study of protein structural dynamics. The tryptophan analogue, 7-aza-Trp (7AW) was incorporated in the BLUF domain of the Activation of Photopigment and pucA (AppA) photoreceptor in order to investigate the functional dynamics of the crucial W104 residue during photoactivation of the protein. The 7-aza modification to Trp makes selective excitation possible using 310 nm excitation and 380 nm emission, separating the signals of interest from other Trp and Tyr residues. We used Förster energy transfer (FRET) between 7AW and the flavin to estimate the distance between Trp and flavin in both the light- and dark-adapted states in solution. Nanosecond fluorescence anisotropy decay and picosecond fluorescence lifetime measurements ...

PLOS ONE

Leiomodin proteins are vertebrate homologues of tropomodulin, having a role in the assembly and m... more Leiomodin proteins are vertebrate homologues of tropomodulin, having a role in the assembly and maintenance of muscle thin filaments. Leiomodin2 contains an N-terminal tropomodulin homolog fragment including tropomyosin-, and actin-binding sites, and a C-terminal Wiskott-Aldrich syndrome homology 2 actin-binding domain. The cardiac leiomodin2 isoform associates to the pointed end of actin filaments, where it supports the lengthening of thin filaments and competes with tropomodulin. It was recently found that cardiac leiomo-din2 can localise also along the length of sarcomeric actin filaments. While the activities of leiomodin2 related to pointed end binding are relatively well described, the potential side binding activity and its functional consequences are less well understood. To better understand the biological functions of leiomodin2, in the present work we analysed the structural features and the activities of Rattus norvegicus cardiac leiomodin2 in actin dynamics by spectroscopic and high-speed sedimentation approaches. By monitoring the fluorescence parameters of leiomodin2 tryptophan residues we found that it possesses flexible, intrinsically disordered regions. Leiomodin2 accelerates the polymerisation of actin in an ionic strength dependent manner, which relies on its N-terminal regions. Importantly, we demonstrate that leiomodin2 binds to the sides of actin filaments and induces structural alterations in actin filaments. Upon its interaction with the filaments leiomodin2 decreases the actinactivated Mg 2+-ATPase activity of skeletal muscle myosin. These observations suggest that through its binding to side of actin filaments and its effect on myosin activity leiomodin2 has more functions in muscle cells than it was indicated in previous studies.

Journal of Muscle Research and Cell Motility, Feb 1, 2006

The EMBO Journal, Jan 14, 2004

Biochemical Journal, Jul 1, 2002

Scientific Reports, 2020

PLoS ONE, 2013

Biophysical Journal, 2022

Polymers

Crystals

Materials & Design

Scientific Reports

Cells

Scientific Reports

PLOS ONE