91 research outputs found
Hydrophobic Motif Phosphorylation Coordinates Activity and Polar Localization of the Neurospora crassa Nuclear Dbf2-Related Kinase COT1
No full textNuclear Dbf2p-related (NDR) kinases and associated proteins are recognized as a conserved network that regulates eukaryotic cell polarity. NDR kinases require association with MOB adaptor proteins and phosphorylation of two conserved residues in the activation segment and hydrophobic motif for activity and function. We demonstrate that the Neurospora crassa NDR kinase COT1 forms inactive dimers via a conserved N-terminal extension, which is also required for the interaction of the kinase with MOB2 to generate heterocomplexes with basal activity. Basal kinase activity also requires autophosphorylation of the COT1-MOB2 complex in the activation segment, while hydrophobic motif phosphorylation of COT1 by the germinal center kinase POD6 fully activates COT1 through induction of a conformational change. Hydrophobic motif phosphorylation is also required for plasma membrane association of the COT1-MOB2 complex. MOB2 further restricts the membrane-associated kinase complex to the hyphal apex to promote polar cell growth. These data support an integrated mechanism of NDR kinase regulation in vivo, in which kinase activation and cellular localization of COT1 are coordinated by dual phosphorylation and interaction with MOB2
Fungal communication requires the MAK-2 pathway elements STE-20 and RAS-2, the NRC-1 adapter STE-50 and the MAP kinase scaffold HAM-5.
No full textIntercellular communication is critical for the survival of unicellular organisms as well as for the development and function of multicellular tissues. Cell-to-cell signaling is also required to develop the interconnected mycelial network characteristic of filamentous fungi and is a prerequisite for symbiotic and pathogenic host colonization achieved by molds. Somatic cell-cell communication and subsequent cell fusion is governed by the MAK-2 mitogen activated protein kinase (MAPK) cascade in the filamentous ascomycete model Neurospora crassa, yet the composition and mode of regulation of the MAK-2 pathway are currently unclear. In order to identify additional components involved in MAK-2 signaling we performed affinity purification experiments coupled to mass spectrometry with strains expressing functional GFP-fusion proteins of the MAPK cascade. This approach identified STE-50 as a regulatory subunit of the Ste11p homolog NRC-1 and HAM-5 as cell-communication-specific scaffold protein of the MAPK cascade. Moreover, we defined a network of proteins consisting of two Ste20-related kinases, the small GTPase RAS-2 and the adenylate cyclase capping protein CAP-1 that function upstream of the MAK-2 pathway and whose signals converge on the NRC-1/STE-50 MAP3K complex and the HAM-5 scaffold. Finally, our data suggest an involvement of the striatin interacting phosphatase and kinase (STRIPAK) complex, the casein kinase 2 heterodimer, the phospholipid flippase modulators YPK-1 and NRC-2 and motor protein-dependent vesicle trafficking in the regulation of MAK-2 pathway activity and function. Taken together, these data will have significant implications for our mechanistic understanding of MAPK signaling and for homotypic cell-cell communication in fungi and higher eukaryotes
HAM-2 and HAM-3 are central for the assembly of the Neurospora STRIPAK complex at the nuclear envelope and regulate nuclear accumulation of the MAP kinase MAK-1 in a MAK-2-dependent manner
No full textIntercellular communication and somatic cell fusion are important for fungal colony establishment, multicellular differentiation and have been associated with host colonization and virulence of pathogenic species. By a combination of genetic, biochemical and live cell imaging techniques, we characterized the Neurospora crassaSTRIPAK complex that is essential for self-signalling and consists of the six proteins HAM-2/STRIP, HAM-3/striatin, HAM-4/SLMAP, MOB-3/phocein, PPG-1/PP2A-C and PP2A-A. We describe that the core STRIPAK components HAM-2 and HAM-3 are central for the assembly of the complex at the nuclear envelope, while the phosphatase PPG-1 only transiently associates with this central subcomplex. Our data connect the STRIPAK complex with two MAP kinase pathways: (i) nuclear accumulation of the cell wall integrity MAP kinase MAK-1 depends on the functional integrity of the STRIPAK complex at the nuclear envelope, and (ii) phosphorylation of MOB-3 by the MAP kinase MAK-2 impacts the nuclear accumulation of MAK-1. In summary, these data support a model, in which MAK-2-dependent phosphorylation of MOB-3 is part of a MAK-1 import mechanism. Although self-communication remained intact in the absence of nuclear MAK-1 accumulation, supporting the presence of multiple mechanisms that co-ordinate robust intercellular communication, proper fruiting body morphology was dependent on the MAK-2-phosphorylated N-terminus of MOB-3
Two NDR kinase-MOB complexes function as distinct modules during septum formation and tip extension in Neurospora crassa
No full textP>NDR kinases are important for growth and differentiation and require interaction with MOB proteins for activity and function. We characterized the NDR kinases and MOB activators in Neurospora crassa and identified two NDR kinases (COT1 and DBF2) and four MOB proteins (MOB1, MOB2A, MOB2B and MOB3/phocein) that form two functional NDR-MOB protein complexes. The MOB1-DBF2 complex is not only essential for septum formation in vegetative cells and during conidiation, but also functions during sexual fruiting body development and ascosporogenesis. The two MOB2-type proteins interact with both COT1 isoforms and control polar tip extension and branching by regulating COT1 activity. The conserved region directly preceding the kinase domain of COT1 is sufficient for the formation of COT1-MOB2 heterodimers, but also for kinase homodimerization. An additional N-terminal extension that is poorly conserved, but present in most fungal NDR kinases, is required for further stabilization of both types of interactions and for stimulating COT1 activity. COT1 lacking this region is degraded in a mob-2 background. We propose a specific role of MOB3/phocein during vegetative cell fusion, fruiting body development and ascosporogenesis that is unrelated to the three other MOB proteins and NDR kinase signalling
Proper actin ring formation and septum constriction requires coordinated regulation of SIN and MOR pathways through the germinal centre kinase MST-1.
No full textNuclear DBF2p-related (NDR) kinases constitute a functionally conserved protein family of eukaryotic regulators that control cell division and polarity. In fungi, they function as effector kinases of the morphogenesis (MOR) and septation initiation (SIN) networks and are activated by pathway-specific germinal centre (GC) kinases. We characterized a third GC kinase, MST-1, that connects both kinase cascades. Genetic and biochemical interactions with SIN components and life cell imaging identify MST-1 as SIN-associated kinase that functions in parallel with the GC kinase SID-1 to activate the SIN-effector kinase DBF-2. SID-1 and MST-1 are both regulated by the upstream SIN kinase CDC-7, yet in an opposite manner. Aberrant cortical actomyosin rings are formed in Δmst-1, which resulted in mis-positioned septa and irregular spirals, indicating that MST-1-dependent regulation of the SIN is required for proper formation and constriction of the septal actomyosin ring. However, MST-1 also interacts with several components of the MOR network and modulates MOR activity at multiple levels. MST-1 functions as promiscuous enzyme and also activates the MOR effector kinase COT-1 through hydrophobic motif phosphorylation. In addition, MST-1 physically interacts with the MOR kinase POD-6, and dimerization of both proteins inactivates the GC kinase hetero-complex. These data specify an antagonistic relationship between the SIN and MOR during septum formation in the filamentous ascomycete model Neurospora crassa that is, at least in part, coordinated through the GC kinase MST-1. The similarity of the SIN and MOR pathways to the animal Hippo and Ndr pathways, respectively, suggests that intensive cross-communication between distinct NDR kinase modules may also be relevant for the homologous NDR kinases of higher eukaryotes
The NDR kinase scaffold HYM1/MO25 is essential for MAK2 map kinase signaling in Neurospora crassa.
No full textCell communication is essential for eukaryotic development, but our knowledge of molecules and mechanisms required for intercellular communication is fragmentary. In particular, the connection between signal sensing and regulation of cell polarity is poorly understood. In the filamentous ascomycete Neurospora crassa, germinating spores mutually attract each other and subsequently fuse. During these tropic interactions, the two communicating cells rapidly alternate between two different physiological states, probably associated with signal delivery and response. The MAK2 MAP kinase cascade mediates cell-cell signaling. Here, we show that the conserved scaffolding protein HYM1/MO25 controls the cell shape-regulating NDR kinase module as well as the signal-receiving MAP kinase cascade. HYM1 functions as an integral part of the COT1 NDR kinase complex to regulate the interaction with its upstream kinase POD6 and thereby COT1 activity. In addition, HYM1 interacts with NRC1, MEK2, and MAK2, the three kinases of the MAK2 MAP kinase cascade, and co-localizes with MAK2 at the apex of growing cells. During cell fusion, the three kinases of the MAP kinase module as well as HYM1 are recruited to the point of cell-cell contact. hym-1 mutants phenocopy all defects observed for MAK2 pathway mutants by abolishing MAK2 activity. An NRC1-MEK2 fusion protein reconstitutes MAK2 signaling in hym-1, while constitutive activation of NRC1 and MEK2 does not. These data identify HYM1 as a novel regulator of the NRC1-MEK2-MAK2 pathway, which may coordinate NDR and MAP kinase signaling during cell polarity and intercellular communication
Cretaceous palynomorphs from the James Ross Island area, Antarctica - a pilot study
No full textFaunas of ammonites and bivalves, aquatic floras of dinocysts and prasinophycean/chlorophycean algae, and land-plant florules of spores, pollen, and fungal palynomorphs are reported from Cretaceous sedimentary rocks of James Ross Island, Dundee Island, and Cape Longing, Antarctic Peninsula. Ages adduced from the megafaunas are mostly verified by the dinocyst floras. Mid- to Late Cretaceous dinocyst assemblages of the Antarctic Peninsula confirm wide distribution, in southern high latitude oceanic regions, of the successive Muderongia, Heterosphaeridium, and Isabelidinium floras. Contemporaneous land-plant floras comprised a succession of rainforest communities having affiliations with vegetation fringing the southern Atlantic Ocean and in Australasia. Mid-Cretaceous-araucarean/podocarp rainforests were modified during the Campanian by the introduction of Nothofagus. Evidence is advanced for step-wise migration of certain cryptogam and angiosperm elements within southern Gondwana. The palynofloras comprise 62 cryptogam-spore, 54 pollen, 80 dinocyst, and nine prasinophycean/chlorophycean taxa. A trilete spore species, Kraeuselisporites laceratus Norris 1968 (senior synonym of K. jubatus Dettmann and Playford 1968) is newly combined with the genus Perotrilites Erdtmann ex Couper 1953. - from Author
Gap-Mending im Studium der Sozialen Arbeit: Entwicklung einer Seminarevaluation
No full textKein Abstract vorhande
Interorganisationale Zusammenarbeit von Inobhutnahme - Einrichtungen im Kontext einer Kindeswohlgefährdung
No full textkein Abstract vorhande
Service User Involvement - SUI Newsletter - Ausgabe Februar 2020
No full textDer jährlich erscheinende Newsletter berichtet über Aktivitäten rund um Service User Involvement an Hochschulen im deutschsprachigen Raum. Sie finden in dieser Ausgabe folgende Beiträge: Zunächst berichtet Gaby Straßburger über einen hochschulinternen Prozess der kollegialen Lehrentwicklung zu Service User Involvement an der Katholischen Hochschule Berlin. Judith Rieger hat mittlerweile eine Vielzahl an reflexiven und evaluierenden Zwischenauswertungen mit Studierenden erhoben und verweist in ihrem Beitrag auf drei zentrale Positionen. Kerstin Rock hat an der htw saar im Rahmen eines Studientages die Beteiligung von Adressat*innen in verschiedenen Workshops für die Studierenden erlebbar werden lassen und berichtet von den Ergebnissen der anschließenden Befragung. Christoph Walther und Sigrid Zauter erläutern die neue Online-Plattform „Trinetz“. Sie wurde für die Begleitung in psychischen Krisen entwickelt und vernetzt Genesungsbegleiter* innen, Arbeitgeber*innen und interessierte Menschen. Marlene-Anne Dettmann verrät ihre Strategien für die Bekanntmachung von SUI an den Fachhochschulen Potsdam und Hamburg und beschreibt ihre jeweiligen Aktivitäten. Abschließend stellt Katharina Scholz einige Aspekte ihrer BA-Thesis vor, in der sie sich mit Lehr-Evaluation für Seminare mit Beteiligung von Adressat*innen befasst hat. Am Ende des Newsletters finden Sie aktuelle Publikationen von Autor*innen unseres Netzwerkes, anstehende Termine.Unknow
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