József Mihály - Academia.edu (original) (raw)

Papers by József Mihály

Genetics, 2016

The noncanonical Frizzled/planar cell polarity (PCP) pathway regulates establishment of polarity ... more The noncanonical Frizzled/planar cell polarity (PCP) pathway regulates establishment of polarity within the plane of an epithelium to generate diversity of cell fates, asymmetric, but highly aligned structures, or to orchestrate the directional migration of cells during convergent extension during vertebrate gastrulation. In Drosophila, PCP signaling is essential to orient actin wing hairs and to align ommatidia in the eye, in part by coordinating the movement of groups of photoreceptor cells during ommatidial rotation. Importantly, the coordination of PCP signaling with changes in the cytoskeleton is essential for proper epithelial polarity. Formins polymerize linear actin filaments and are key regulators of the actin cytoskeleton. Here, we show that the diaphanous-related formin, Frl, the single fly member of the FMNL (formin related in leukocytes/formin-like) formin subfamily affects ommatidial rotation in the Drosophila eye and is controlled by the Rho family GTPase Cdc42. Inter...

bioRxiv, 2021

Myofibrils are long intracellular cables specific to muscles, composed mainly of actin and myosin... more Myofibrils are long intracellular cables specific to muscles, composed mainly of actin and myosin filaments. The actin and myosin filaments are organized into repeated units called sarcomeres, which form the myofibril cables. Muscle contraction is achieved by the simultaneous shortening of sarcomeres and for a highly coordinated contraction to occur all sarcomeres should have the same size. Muscles have evolved a variety of ways to ensure sarcomere homogeneity, one example being the controlled oligomerization of Zasp proteins that sets the diameter of the myofibril. To understand how Zasp proteins effect myofibril growth, we looked for Zasp-binding proteins at the Z-disc. We found that the E1 subunit of the oxoglutarate dehydrogenase complex is recruited to the Z-disc by Zasp52 and is required to sustain myofibril growth. By making specific mutants, we show that its enzymatic activity is important for myofibril growth, and that the other two subunits of the complex are also required...

Genetics, 2000

The Drosophila melanogaster Ketel gene was identified via the KetelD dominant female sterile muta... more The Drosophila melanogaster Ketel gene was identified via the KetelD dominant female sterile mutations and their ketelr revertant alleles that are recessive zygotic lethals. The maternally acting KetelD mutations inhibit cleavage nuclei formation. We cloned the Ketel gene on the basis of a common breakpoint in 38E1.2-3 in four ketelr alleles. The Ketel+ transgenes rescue ketelr-associated zygotic lethality and slightly reduce KetelD-associated dominant female sterility. Ketel is a single copy gene. It is transcribed to a single 3.6-kb mRNA, predicted to encode the 97-kD Ketel protein. The 884-amino-acid sequence of Ketel is 60% identical and 78% similar to that of human importin-β, the nuclear import receptor for proteins with a classical NLS. Indeed, Ketel supports import of appropriately designed substrates into nuclei of digitonin-permeabilized HeLa cells. As shown by a polyclonal anti-Ketel antibody, nurse cells synthesize and transfer Ketel protein into the oocyte cytoplasm fro...

International Journal of Molecular Sciences

The actin containing tropomyosin and troponin decorated thin filaments form one of the crucial co... more The actin containing tropomyosin and troponin decorated thin filaments form one of the crucial components of the contractile apparatus in muscles. The thin filaments are organized into densely packed lattices interdigitated with myosin-based thick filaments. The crossbridge interactions between these myofilaments drive muscle contraction, and the degree of myofilament overlap is a key factor of contractile force determination. As such, the optimal length of the thin filaments is critical for efficient activity, therefore, this parameter is precisely controlled according to the workload of a given muscle. Thin filament length is thought to be regulated by two major, but only partially understood mechanisms: it is set by (i) factors that mediate the assembly of filaments from monomers and catalyze their elongation, and (ii) by factors that specify their length and uniformity. Mutations affecting these factors can alter the length of thin filaments, and in human cases, many of them are...

Applied Microbiology and Biotechnology, 2005

Biochemical and pharmacological properties of biosurfactants produced at 45°C temperature by Pseu... more Biochemical and pharmacological properties of biosurfactants produced at 45°C temperature by Pseudomonas aeruginosa mucoid (M) and non-mucoid (NM) strains, isolated from hydrocarbon-contaminated soil samples, were characterized. Both the strains secreted appreciable amount of biosurfactants (5.0-6.5 g/l), responsible for the reduction of surface tension of the medium from 68 to 29±0.5 mN/m post 96 h of growth. Maximum yield of biosurfactants was observed following the supplementation of NH 4 Cl and glycerol as nitrogenous source and carbon source, respectively. These thermostable biosurfactants exhibited strong emulsifying property and could release appreciable amount of oil from saturated sand-pack column. Pharmacological characterization of these biosurfactants revealed that they induced dose-dependent hemolysis and coagulation of platelet-poor plasma but were non-detrimental to chicken lung, liver, heart and kidney tissues. Our study has documented that biosurfactants from P. aeruginosa M and NM strains could be exploited for use in petroleum sectors as well in pharmaceutical industries.

PLoS Genetics, 2014

During muscle development, myosin and actin containing filaments assemble into the highly organiz... more During muscle development, myosin and actin containing filaments assemble into the highly organized sarcomeric structure critical for muscle function. Although sarcomerogenesis clearly involves the de novo formation of actin filaments, this process remained poorly understood. Here we show that mouse and Drosophila members of the DAAM formin family are sarcomere-associated actin assembly factors enriched at the Z-disc and M-band. Analysis of dDAAM mutants revealed a pivotal role in myofibrillogenesis of larval somatic muscles, indirect flight muscles and the heart. We found that loss of dDAAM function results in multiple defects in sarcomere development including thin and thick filament disorganization, Zdisc and M-band formation, and a near complete absence of the myofibrillar lattice. Collectively, our data suggest that dDAAM is required for the initial assembly of thin filaments, and subsequently it promotes filament elongation by assembling short actin polymers that anneal to the pointed end of the growing filaments, and by antagonizing the capping protein Tropomodulin.

Cells

Axonal growth is mediated by coordinated changes of the actin and microtubule (MT) cytoskeleton. ... more Axonal growth is mediated by coordinated changes of the actin and microtubule (MT) cytoskeleton. Ample evidence suggests that members of the formin protein family are involved in the coordination of these cytoskeletal rearrangements, but the molecular mechanisms of the formin-dependent actin–microtubule crosstalk remains largely elusive. Of the six Drosophila formins, DAAM was shown to play a pivotal role during axonal growth in all stages of nervous system development, while FRL was implicated in axonal development in the adult brain. Here, we aimed to investigate the potentially redundant function of these two formins, and we attempted to clarify which molecular activities are important for axonal growth. We used a combination of genetic analyses, cellular assays and biochemical approaches to demonstrate that the actin-processing activity of DAAM is indispensable for axonal growth in every developmental condition. In addition, we identified a novel MT-binding motif within the FH2 ...

F-actin networks are important structural determinants of cell shape and morphogenesis. They are ... more F-actin networks are important structural determinants of cell shape and morphogenesis. They are regulated through a number of actin-binding proteins. The function of many of these proteins is well understood, but very little is known about how they cooperate and integrate their activities in cellular contexts. Here, we have focussed on the cellular roles of actin regulators in controlling filopodial dynamics. Filopodia are needle-shaped, actin-driven cell protrusions with characteristic features that are well conserved amongst vertebrates and invertebrates. However, existing models of filopodia formation are still incomplete and controversial, pieced together from a wide range of different organisms and cell types. Therefore, we used embryonic Drosophila primary neurons as one consistent cellular model to study filopodia regulation. Our data for loss-of-function of capping proteins, enabled, different Arp2/3 complex components, the formin DAAM and profilin reveal characteristic cha...

Concurrent activating mutations of the Notch and PI3K/Akt signalling pathways cooperate in the in... more Concurrent activating mutations of the Notch and PI3K/Akt signalling pathways cooperate in the induction of aggressive cancers. Unfortunately, direct targeting of any of these aberrant pathways can result in severe side effects due to their broad physiological roles in multiple organs. Here, using an unbiased chemical in vivo screen in Drosophila we identified compounds that suppress the activity of the pro-inflammatory enzymes, nitric oxide synthase (NOS) and lipoxygenase (LOX), capable to block oncogenic Notch-PI3K/Akt cooperation without unwanted side effects. Genetic inactivation of NOS and LOX signalling components mirrors the anti-tumorigenic effect of the hit compounds. We show that NOS activity and immunosuppression associated to inflammation facilitates Notch-mediated tumorigenesis. Our study reveals an unnoticed immune inflammatory process underlying Notch-PI3K/Akt tumours and exposes NOS as a druggable target for anti-cancer therapeutic development.

Fontosabb eredmenyek Kimutattuk, hogy a bithorax komplexben (Bx-C) a Polycomb Response Elementek ... more Fontosabb eredmenyek Kimutattuk, hogy a bithorax komplexben (Bx-C) a Polycomb Response Elementek (PRE-k), es a hozzajuk kapcsolodo Polycomb feherjek nemcsak a cisz-regulator regiok inaktiv/zart allapotanak fenntartasaban jatszanak fontos szerepet, hanem az aktiv/nyilt allapotu cisz-regulatorokban talalhato enhanszerek hatasanak modulalasaban is. Ezt a hatas ugy fejti ki, hogy fizikailag a celgen promoterehez kotődik. Ezzel osszefuggesben kimutattuk egy, a bxd PRE-vel reszben atfedő Targetalo Elem (TE) jelenletet. A TE a PRE-hez hasonloan modularis szerkezetű. Igazoltuk, hogy ez az elem nemcsak a PRE promoterhez valo kőtődeseben jatszik szerepet, hanem reszt vesz a bxd regioban talalhato enhanszereknek az Ubx promotere kore valo szervezeseben, azaz az „acticve chromatin hub” kialakitasaban. A TE ezt a funkciojat ektopikus kornyezetben, az iab-7 cisz regulatorban is megőrzi. A PRE-től hatarolo elemmel elvalasztott bxd enhanszerek ektopikus aktivitast mutatnak, amely mind fenotipus analizissel, mind markergen expressziojanak kovetesevel kimutathato. Kinutattuk, hogy az ebi gen a Polycomb csoport genjei koze sorolando, es a polyhomeotic gennel egyutt az aktiv allapotu cisz-regulatorokban fejti ki modulalo hatasat. Kvantitativ RTPCR segitsegevel kimutattuk, hogy az Abd-B RNS mennyisege korulbelul duplajara nő polyhomeotic mutans hatteren. | We showed that Polycomb Response Elements (PREs) and Polycomb proteins bound to them play an important role not only in maintaining inactive/closed conformation of cis-regulatory elements in the bithorax complex, but they are also involved in modulating the regulatory output of enhancers in the active/open domains. This latter effect is mediated by direct physical contact between the PRE and the promoter – enhancer complex. In connection with this we demonstrated the presence of a Targeting Element (TE) that partially overlaps with the bxd PRE. TE is, similarly to the PRE, modularly organized. We showed that this element is involved not only in targeting the PRE to the Ubx promoter, but also part of the machinery organizing the active chromatin hub around cognate promoter. We also demonstrated that the TE maintains its activity in ectopic context, in the iab-7 cis-regulatory region. Enhancers separated from the bxd PRE by a boundary region exhibit ectopic activity, as revealed by both phenotypic analysis and by monitoring the expression pattern of a marker gene. We identified the ebi gene as an unusual Polycomb group member, which, similarly to the polyhometic gene, participates in the modulation of enhancer output of active cis-regulatory regions. Using quantitative RTPCR we showed that the amount of the Abd-B RNA is doubled in polyhomeotic mutant background.

Genetics, 1998

The Abd-B gene, one of the three homeotic genes in the Drosophila bithorax complex (BX-C), is req... more The Abd-B gene, one of the three homeotic genes in the Drosophila bithorax complex (BX-C), is required for the proper identity of the fifth through the eighth abdominal segments (corresponding to parasegments 10-14) of the fruitfly. The morphological difference between these four segments is due to the differential expression of Abd-B, which is achieved by the action of the parasegment-specific cis-regulatory regions infra-abdominal-5 (iab-5), -6, -7 and -8. The dominant gain-of-function mutation Frontabdominal-7 (Fab-7) removes a boundary separating two of these cis-regulatory regions, iab-6 and iab-7. As a consequence of the Fab-7 deletion, the parasegment 12- (PS12-) specific iab-7 is ectopically activated in PS11. This results in the transformation of the sixth abdominal segment (A6) into the seventh (A7) in Fab-7 flies. Here we report that point mutations of the Abd-B gene in trans suppress the Fab-7 phenotype in a pairing-dependent manner and thus represent a type of transvect...

A Drosophila sejtkozvetitette immunvalaszanak szabalyozasat vizsgaltuk valamint molekularis immun... more A Drosophila sejtkozvetitette immunvalaszanak szabalyozasat vizsgaltuk valamint molekularis immunologiai es genetikai ismeretek elsajatitasat es projekt epiteset tettuk lehetőve a tudomany irant erdeklődő diakok es kutatok szamara.Adult Drosophila versejtjeire, makrofagokra es a lamellocitakra jellemző markereket azonositottunk.Az L5 antigen a lamellocitak differencialodasanak a szuppresszora.A P1 antigenről (Nimrod) megallapitottuk, hogy reszt vesz a fagocitozisban.A P1 molekula jellegzetes motivumot hordoz (Nim-repeat),mely egy szupercsaladot hataroz meg:tagjai a kodolo gen kozvetlen kornyezeteben helyezkednek el. Javaslatot tettunk a Nim repeat kialakulasanak a modelljere,leirtuk a Nimrod szuprcsalad lehetseges evoluciojat.A verkepzest es a versejtek funkcioit szabalyozo geneket es molekulakat azonositottunk.Egy epigenetikus regulatorrol megallapitottuk,hogy a versejtek osztodasat,egy mestergenről pedig,hogy a lamellocitak differencialodasat szabalyozza.RNSi mutansgyűjtemenyben a...

A Projekt kereteben a.) a versejtmarker panelt in vivo lamellocita markerrel egeszitettuk ki. b.)... more A Projekt kereteben a.) a versejtmarker panelt in vivo lamellocita markerrel egeszitettuk ki. b.) a Trol molekulat, az apoptotikus sejteket felismerő receptorkent definialtuk. c.) jellemeztuk az immunkompartmentumok funkcioit es meghataroztuk a sejtes elemek eredetet. A versejtkepző kompartmentumok az embrioban es a larvaban egymastol elhataroltak, mig az immunvalasz soran valamennyi kompartmentum reszt vesz a versejtek kepzeseben. A lamellocitak fejlődese tobb lepesben zajlik a szesszilis szovet kezdeti es fő reszvetelevel. A lamellocitak plazmatocita jellegű sejtekből kepződnek ezert igazoltnak latjuk, hogy a fagocita sejtek nem terminalisan differencialodott sejtek, hanem immunindukciot kovetően lamellocitakka alakulhatnak, mely nagyfoku plaszticitasukat mutatja. d.) immun-modulkent jellemezhető genklasztert azonositottunk Drosophilaban es egyeb rovarfajokban. A genklaszter egyes tagjai reszt vesznek a mikrobak opszonizalasaban, sejthez koteseben es a fagocitozis folyamataban. e....

A Drosophila melanogaster protein foszfataz genjeinek tanulmanyozasahoz genomikus adatbazis kutat... more A Drosophila melanogaster protein foszfataz genjeinek tanulmanyozasahoz genomikus adatbazis kutatas alapjan tobb gent valasztottunk ki, amelyekre a kozelben talalhato P-elemek remobilizalasaval mutaciokat indukaltunk. Az indukalt mutaciok genetikai es molekularis vizsgalataval kovetkeztettunk a genek funkciojara. Megallapitottuk, hogy a CG9238 gen mutacioja sejtletalitast eredmenyez, es a glikogen-anyagcseret gatolja. A CG9238 genetikai kolcsonhatasban van az ovoD gennel. Kimutattuk, hogy a CG15031 gen termeke, amit PPYR1-nek neveztunk el, a PPY protein foszfatazzal stabil feherje-feherje komplexet alkot. A PPYR1-nek ket izoformaja van, amelyek expresszioja elterő szovetspecifitast mutat. A maternalis eredetű izoforma a petekamrakban es a korai embriokban talalhato, mig a zigotikus feherje csak a herekben fordul elő. A PPYR1 eredendően rendezetlen szerkezetet es RNS-kotő kepesseget in vitro kiserletekben igazoltuk. A protein foszfatazokkal egyutt a jelatviteli utakban resztvevő mas ...

With the advent of super-resolution microscopy, we gained a powerful toolbox to bridge the gap be... more With the advent of super-resolution microscopy, we gained a powerful toolbox to bridge the gap between the cellular- and molecular-level analysis of living organisms. Although nanoscopy is broadly applicable, classical model organisms, such as fruit flies, worms and mice, remained the leading subjects because combining the strength of sophisticated genetics, biochemistry and electrophysiology with the unparalleled resolution provided by super-resolution imaging appears as one of the most efficient approaches to understanding the basic cell biological questions and the molecular complexity of life. Here, we summarize the major nanoscopic techniques and illustrate how these approaches were used in Drosophila model systems to revisit a series of well-known cell biological phenomena. These investigations clearly demonstrate that instead of simply achieving an improvement in image quality, nanoscopy goes far beyond with its immense potential to discover novel structural and mechanistic a...

Development

Dendrite shape impacts functional connectivity and is mediated by organization and dynamics of cy... more Dendrite shape impacts functional connectivity and is mediated by organization and dynamics of cytoskeletal fibers. Identifying the molecular factors that regulate dendritic cytoskeletal architecture is therefore important in understanding the mechanistic links between cytoskeletal organization and neuronal function. We identified Formin 3 (Form3) as an essential regulator of cytoskeletal architecture in nociceptive sensory neurons in Drosophila larvae. Time course analyses reveal that Form3 is cell-autonomously required to promote dendritic arbor complexity. We show that form3 is required for the maintenance of a population of stable dendritic microtubules (MTs), and mutants exhibit defects in the localization of dendritic mitochondria, satellite Golgi, and the TRPA channel Painless. Form3 directly interacts with MTs via FH1-FH2 domains. Mutations in human inverted formin 2 (INF2; ortholog of form3) have been causally linked to Charcot–Marie–Tooth (CMT) disease. CMT sensory neuropa...

Frontiers in Molecular Biosciences