@article{StollFeldhaarFraunholzetal.2010,
  author    = {Stoll, Sascha and Feldhaar, Heike and Fraunholz, Martin J. and Gross, Roy},
  title     = {Bacteriocyte dynamics during development of a holometabolous insect, the carpenter ant Camponotus floridanus},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-67950},
  year      = {2010},
  abstract  = {Background: The carpenter ant Camponotus floridanus harbors obligate intracellular mutualistic bacteria (Blochmannia floridanus) in specialized cells, the bacteriocytes, intercalated in their midgut tissue. The diffuse distribution of bacteriocytes over the midgut tissue is in contrast to many other insects carrying endosymbionts in specialized tissues which are often connected to the midgut but form a distinct organ, the bacteriome. C.floridanus is a holometabolous insect which undergoes a complete metamorphosis. During pupal stages a complete restructuring of the inner organs including the digestive tract takes place. So far, nothing was known about maintenance of endosymbionts during this life stage of a holometabolous insect. It was shown previously that the number of Blochmannia increases strongly during metamorphosis. This implicates an important function of Blochmannia in this developmental phase during which the animals are metabolically very active but do not have access to external food resources. Previous experiments have shown a nutritional contribution of the bacteria to host metabolism by production of essential amino acids and urease-mediated nitrogen recycling. In adult hosts the symbiosis appears to degenerate with increasing age of the animals. Results: We investigated the distribution and dynamics of endosymbiotic bacteria and bacteriocytes at different stages during development of the animals from larva to imago by confocal laser scanning microscopy. The number of bacteriocytes in relation to symbiont-free midgut cells varied strongly over different developmental stages. Especially during metamorphosis the relative number of bacteria-filled bacteriocytes increased strongly when the larval midgut epithelium is shed. During this developmental stage the midgut itself became a huge symbiotic organ consisting almost exclusively of cells harboring bacteria. In fact, during this phase some bacteria were also found in midgut cells other than bacteriocytes indicating a cell-invasive capacity of Blochmannia. In adult animals the number of bacteriocytes generally decreased. Conclusions: During the life cycle of the animals the distribution of bacteriocytes and of Blochmannia endosymbionts is remarkably dynamic. Our data show how the endosymbiont is retained within the midgut tissue during metamorphosis thereby ensuring the maintenance of the intracellular endosymbiosis despite a massive reorganization of the midgut tissue. The transformation of the entire midgut into a symbiotic organ during pupal stages underscores the important role of Blochmannia for its host in particular during metamorphosis.},
  subject      = {Camponotus floridanus},
  language  = {en}
}
@phdthesis{Kapustjansky2011,
  author    = {Kapustjansky, Alexander},
  title     = {In vivo imaging and optogenetic approach to study the formation of olfactory memory and locomotor behaviour in Drosophila melanogaster},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-69535},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2011},
  abstract  = {Understanding of complex interactions and events in a nervous system, leading from the molecular level up to certain behavioural patterns calls for interdisciplinary interactions of various research areas. The goal of the presented work is to achieve such an interdisciplinary approach to study and manipulate animal behaviour and its underlying mechanisms. Optical in vivo imaging is a new constantly evolving method, allowing one to study not only the local but also wide reaching activity in the nervous system. Due to ease of its genetic accessibility Drosophila melanogaster represents an extraordinary experimental organism to utilize not only imaging but also various optogenetic techniques to study the neuronal underpinnings of behaviour. In this study four genetically encoded sensors were used to investigate the temporal dynamics of cAMP concentration changes in the horizontal lobes of the mushroom body, a brain area important for learning and memory, in response to various physiological and pharmacological stimuli. Several transgenic lines with various genomic insertion sites for the sensor constructs Epac1, Epac2, Epac2K390E and HCN2 were screened for the best signal quality, one line was selected for further experiments. The in vivo functionality of the sensor was assessed via pharmacological application of 8-bromo-cAMP as well as Forskolin, a substance stimulating cAMP producing adenylyl cyclases. This was followed by recording of the cAMP dynamics in response to the application of dopamine and octopamine, as well as to the presentation of electric shock, odorants or a simulated olfactory signal, induced by acetylcholine application to the observed brain area. In addition the interaction between the shock and the simulated olfactory signal by simultaneous presentation of both stimuli was studied. Preliminary results are supporting a coincidence detection mechanism at the level of the adenylyl cyclase as postulated by the present model for classical olfactory conditioning. In a second series of experiments an effort was made to selecticvely activate a subset of neurons via the optogenetic tool Channelrhodopsin (ChR2). This was achieved by recording the behaviour of the fly in a walking ball paradigm. A new method was developed to analyse the walking behaviour of the animal whose brain was made optically accessible via a dissection technique, as used for imaging, thus allowing one to target selected brain areas. Using the Gal4-UAS system the protocerebral bridge, a substructure of the central complex, was highlighted by expressing the ChR2 tagged by fluorescent protein EYFP. First behavioural recordings of such specially prepared animals were made. Lastly a new experimental paradigm for single animal conditioning was developed (Shock Box). Its design is based on the established Heat Box paradigm, however in addition to spatial and operant conditioning available in the Heat Box, the design of the new paradigm allows one to set up experiments to study classical and semioperant olfactory conditioning, as well as semioperant place learning and operant no idleness experiments. First experiments involving place learning were successfully performed in the new apparatus.},
  subject      = {Taufliege},
  language  = {en}
}
@article{FriedrichRahmannWeigeletal.2010,
  author    = {Friedrich, Torben and Rahmann, Sven and Weigel, Wilfried and Rabsch, Wolfgang and Fruth, Angelika and Ron, Eliora and Gunzer, Florian and Dandekar, Thomas and Hacker, Joerg and Mueller, Tobias and Dobrindt, Ulrich},
  title     = {High-throughput microarray technology in diagnostics of enterobacteria based on genome-wide probe selection and regression analysis},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-67936},
  year      = {2010},
  abstract  = {The Enterobacteriaceae comprise a large number of clinically relevant species with several individual subspecies. Overlapping virulence-associated gene pools and the high overall genome plasticity often interferes with correct enterobacterial strain typing and risk assessment. Array technology offers a fast, reproducible and standardisable means for bacterial typing and thus provides many advantages for bacterial diagnostics, risk assessment and surveillance. The development of highly discriminative broad-range microbial diagnostic microarrays remains a challenge, because of marked genome plasticity of many bacterial pathogens. Results: We developed a DNA microarray for strain typing and detection of major antimicrobial resistance genes of clinically relevant enterobacteria. For this purpose, we applied a global genome-wide probe selection strategy on 32 available complete enterobacterial genomes combined with a regression model for pathogen classification. The discriminative power of the probe set was further tested in silico on 15 additional complete enterobacterial genome sequences. DNA microarrays based on the selected probes were used to type 92 clinical enterobacterial isolates. Phenotypic tests confirmed the array-based typing results and corroborate that the selected probes allowed correct typing and prediction of major antibiotic resistances of clinically relevant Enterobacteriaceae, including the subspecies level, e.g. the reliable distinction of different E. coli pathotypes. Conclusions: Our results demonstrate that the global probe selection approach based on longest common factor statistics as well as the design of a DNA microarray with a restricted set of discriminative probes enables robust discrimination of different enterobacterial variants and represents a proof of concept that can be adopted for diagnostics of a wide range of microbial pathogens. Our approach circumvents misclassifications arising from the application of virulence markers, which are highly affected by horizontal gene transfer. Moreover, a broad range of pathogens have been covered by an efficient probe set size enabling the design of high-throughput diagnostics.},
  subject      = {Mikroarray},
  language  = {en}
}
@article{LaisneyBraaschWalteretal.2010,
  author    = {Laisney, Juliette A. G. C. and Braasch, Ingo and Walter, Ronald B. and Meierjohann, Svenja and Schartl, Manfred},
  title     = {Lineage-specific co-evolution of the Egf receptor/ligand signaling system},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-67922},
  year      = {2010},
  abstract  = {Background: The epidermal growth factor receptor (Egfr) with its numerous ligands has fundamental roles in development, cell differentiation and physiology. Dysfunction of the receptor-ligand system contributes to many human malignancies. Consistent with such various tasks, the Egfr gene family has expanded during vertebrate evolution as a consequence of several rounds of whole genome duplication. Of particular interest is the effect of the fish-specific whole genome duplication (FSGD) on the ligand-receptor system, as it has supplied this largest group of vertebrates with additional opportunities for sub- and/or neofunctionalization in this signaling system. Results: We identified the predicted components of the Egf receptor-ligand signaling system in teleost fishes (medaka, platyfish, stickleback, pufferfishes and zebrafish). We found two duplicated egfr genes, egfra and egfrb, in all available teleost genomes. Surprisingly only one copy for each of the seven Egfr ligands could be identified in most fishes, with zebrafish hbegf being the only exception. Special focus was put on medaka, for which we more closely investigated all Egf receptors and Egfr ligands. The different expression patterns of egfra, egfrb and their ligands in medaka tissues and embryo stages suggest differences in role and function. Preferential co-expression of different subsets of Egfr ligands corroborates the possible subfunctionalization and specialization of the two receptors in adult tissues. Bioinformatic analyses of the ligand-receptor interface between Egfr and its ligands show a very weak evolutionary conservation within this region. Using in vitro analyses of medaka Egfra, we could show that this receptor is only activated by medaka ligands, but not by human EGF. Altogether, our data suggest a lineage-specific Egfr/Egfr ligand co-evolution. Conclusions: Our data indicate that medaka Egfr signaling occurs via its two copies, Egfra and Egfrb, each of them being preferentially coexpressed with different subsets of Egfr ligands. This fish-specific occurrence of Egf receptor specialization offers unique opportunities to study the functions of different Egf receptor-ligand combinations and their biological outputs in vertebrates. Furthermore, our results strongly support the use of homologous ligands in future studies, as sufficient cross-specificity is very unlikely for this ligand/receptor system.},
  subject      = {Epidermaler Wachstumsfaktor-Rezeptor},
  language  = {en}
}
@article{BrocherVogelHock2010,
  author    = {Brocher, Jan and Vogel, Benjamin and Hock, Robert},
  title     = {HMGA1 down-regulation is crucial for chromatin composition and a gene expression profile permitting myogenic differentiation},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-67914},
  year      = {2010},
  abstract  = {Background: High mobility group A (HMGA) proteins regulate gene transcription through architectural modulation of chromatin and the formation of multi-protein complexes on promoter/enhancer regions. Differential expression of HMGA variants has been found to be important for distinct differentiation processes and deregulated expression was linked to several disorders. Here we used mouse C2C12 myoblasts and C2C12 cells stably over-expressing HMGA1a-eGFP to study the impact of deregulated HMGA1 expression levels on cellular differentiation. Results: We found that induction of the myogenic or osteogenic program of C2C12 cells caused an immediate down-regulation of HMGA1. In contrast to wild type C2C12 cells, an engineered cell line with stable overexpression of HMGA1a-eGFP failed to differentiate into myotubes. Immunolocalization studies demonstrated that sustained HMGA1a-eGFP expression prevented myotube formation and chromatin reorganization that normally accompanies differentiation. Western Blot analyses showed that elevated HMGA1a-eGFP levels affected chromatin composition through either down-regulation of histone H1 or premature expression of MeCP2. RT-PCR analyses further revealed that sustained HMGA1a expression also affected myogenic gene expression and caused either down-regulation of genes such as MyoD, myogenin, Igf1, Igf2, Igfbp1-3 or up-regulation of the transcriptional repressor Msx1. Interestingly, siRNA experiments demonstrated that knock-down of HMGA1a was required and sufficient to reactivate the myogenic program in induced HMGA1a over-expressing cells. Conclusions: Our data demonstrate that HMGA1 down-regulation after induction is required to initiate the myogenic program in C2C12 cells. Sustained HMGA1a expression after induction prevents expression of key myogenic factors. This may be due to specific gene regulation and/or global effects on chromatin. Our data further corroborate that altered HMGA1 levels influence the expression of other chromatin proteins. Thus, HMGA1 is able to establish a specific chromatin composition. This work contributes to the understanding of how differential HMGA1 expression is involved in chromatin organization during cellular differentiation processes and it may help to comprehend effects of HMGA1 over-expression occurring in malign or benign tumours.},
  subject      = {HMG-Proteine},
  language  = {en}
}
@article{TeutschbeinHaydnSamansetal.2010,
  author    = {Teutschbein, Janka and Haydn, Johannes M. and Samans, Birgit and Krause, Michael and Eilers, Martin and Schartl, Manfred and Meierjohann, Svenja},
  title     = {Gene expression analysis after receptor tyrosine kinase activation reveals new potential melanoma proteins},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-67900},
  year      = {2010},
  abstract  = {Background: Melanoma is an aggressive tumor with increasing incidence. To develop accurate prognostic markers and targeted therapies, changes leading to malignant transformation of melanocytes need to be understood. In the Xiphophorus melanoma model system, a mutated version of the EGF receptor Xmrk (Xiphophorus melanoma receptor kinase) triggers melanomagenesis. Cellular events downstream of Xmrk, such as the activation of Akt, Ras, B-Raf or Stat5, were also shown to play a role in human melanomagenesis. This makes the elucidation of Xmrk downstream targets a useful method for identifying processes involved in melanoma formation. Methods: Here, we analyzed Xmrk-induced gene expression using a microarray approach. Several highly expressed genes were confirmed by realtime PCR, and pathways responsible for their induction were revealed using small molecule inhibitors. The expression of these genes was also monitored in human melanoma cell lines, and the target gene FOSL1 was knocked down by siRNA. Proliferation and migration of siRNA-treated melanoma cell lines were then investigated. Results: Genes with the strongest upregulation after receptor activation were FOS-like antigen 1 (Fosl1), early growth response 1 (Egr1), osteopontin (Opn), insulin-like growth factor binding protein 3 (Igfbp3), dual-specificity phosphatase 4 (Dusp4), and tumor-associated antigen L6 (Taal6). Interestingly, most genes were blocked in presence of a SRC kinase inhibitor. Importantly, we found that FOSL1, OPN, IGFBP3, DUSP4, and TAAL6 also exhibited increased expression levels in human melanoma cell lines compared to human melanocytes. Knockdown of FOSL1 in human melanoma cell lines reduced their proliferation and migration. Conclusion: Altogether, the data show that the receptor tyrosine kinase Xmrk is a useful tool in the identification of target genes that are commonly expressed in Xmrk-transgenic melanocytes and melanoma cell lines. The identified molecules constitute new possible molecular players in melanoma development. Specifically, a role of FOSL1 in melanomagenic processes is demonstrated. These data are the basis for future detailed analyses of the investigated target genes.},
  language  = {en}
}
@article{VainshteinSanchezBrazmaetal.2010,
  author    = {Vainshtein, Yevhen and Sanchez, Mayka and Brazma, Alvis and Hentze, Matthias W. and Dandekar, Thomas and Muckenthaler, Martina U.},
  title     = {The IronChip evaluation package: a package of perl modules for robust analysis of custom microarrays},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-67869},
  year      = {2010},
  abstract  = {Background: Gene expression studies greatly contribute to our understanding of complex relationships in gene regulatory networks. However, the complexity of array design, production and manipulations are limiting factors, affecting data quality. The use of customized DNA microarrays improves overall data quality in many situations, however, only if for these specifically designed microarrays analysis tools are available. Results: The IronChip Evaluation Package (ICEP) is a collection of Perl utilities and an easy to use data evaluation pipeline for the analysis of microarray data with a focus on data quality of custom-designed microarrays. The package has been developed for the statistical and bioinformatical analysis of the custom cDNA microarray IronChip but can be easily adapted for other cDNA or oligonucleotide-based designed microarray platforms. ICEP uses decision tree-based algorithms to assign quality flags and performs robust analysis based on chip design properties regarding multiple repetitions, ratio cut-off, background and negative controls. Conclusions: ICEP is a stand-alone Windows application to obtain optimal data quality from custom-designed microarrays and is freely available here (see "Additional Files" section) and at: http://www.alice-dsl.net/evgeniy. vainshtein/ICEP/},
  subject      = {Microarray},
  language  = {en}
}
@article{SchmidSchindelinCardonaetal.2010,
  author    = {Schmid, Benjamin and Schindelin, Johannes and Cardona, Albert and Longair, Martin and Heisenberg, Martin},
  title     = {A high-level 3D visualization API for Java and ImageJ},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-67851},
  year      = {2010},
  abstract  = {Background: Current imaging methods such as Magnetic Resonance Imaging (MRI), Confocal microscopy, Electron Microscopy (EM) or Selective Plane Illumination Microscopy (SPIM) yield three-dimensional (3D) data sets in need of appropriate computational methods for their analysis. The reconstruction, segmentation and registration are best approached from the 3D representation of the data set. Results: Here we present a platform-independent framework based on Java and Java 3D for accelerated rendering of biological images. Our framework is seamlessly integrated into ImageJ, a free image processing package with a vast collection of community-developed biological image analysis tools. Our framework enriches the ImageJ software libraries with methods that greatly reduce the complexity of developing image analysis tools in an interactive 3D visualization environment. In particular, we provide high-level access to volume rendering, volume editing, surface extraction, and image annotation. The ability to rely on a library that removes the low-level details enables concentrating software development efforts on the algorithm implementation parts. Conclusions: Our framework enables biomedical image software development to be built with 3D visualization capabilities with very little effort. We offer the source code and convenient binary packages along with extensive documentation at http://3dviewer.neurofly.de.},
  subject      = {Visualisierung},
  language  = {en}
}
@phdthesis{Halder2011,
  author    = {Halder, Partho},
  title     = {Identification and characterization of synaptic proteins of Drosophila melanogaster using monoclonal antibodies of the Wuerzburg Hybridoma Library},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-67325},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2011},
  abstract  = {For a large fraction of the proteins expressed in the human brain only the primary structure is known from the genome project. Proteins conserved in evolution can be studied in genetic models such as Drosophila. In this doctoral thesis monoclonal antibodies (mAbs) from the Wuerzburg Hybridoma library are produced and characterized with the aim to identify the target antigen. The mAb ab52 was found to be an IgM which recognized a cytosolic protein of Mr ~110 kDa on Western blots. The antigen was resolved by two-dimensional gel electrophoresis (2DE) as a single distinct spot. Mass spectrometric analysis of this spot revealed EPS-15 (epidermal growth factor receptor pathway substrate clone 15) to be a strong candidate. Another mAb from the library, aa2, was already found to recognize EPS-15, and comparison of the signal of both mAbs on Western blots of 1D and 2D electrophoretic separations revealed similar patterns, hence indicating that both antigens could represent the same protein. Finally absence of the wild-type signal in homozygous Eps15 mutants in a Western blot with ab52 confirmed the ab52 antigen to be EPS-15. Thus both the mAbs aa2 and ab52 recognize the Drosophila homologue of EPS-15. The mAb aa2, being an IgG, is more suitable for applications like immunoprecipitation (IP). It has already been submitted to the Developmental Studies Hybridoma Bank (DSHB) to be easily available for the entire research community. The mAb na21 was also found to be an IgM. It recognizes a membrane associated antigen of Mr ~10 kDa on Western blots. Due to the membrane associated nature of the protein, it was not possible to resolve it by 2DE and due to the IgM nature of the mAb it was not possible to enrich the antigen by IP. Preliminary attempts to biochemically purify the endogenously expressed protein from the tissue, gave promising results but could not be completed due to lack of time. Thus biochemical purification of the protein seems possible in order to facilitate its identification by mass spectrometry. Several other mAbs were studied for their staining pattern on cryosections and whole mounts of Drosophila brains. However, many of these mAbs stained very few structures in the brain, which indicated that only a very limited amount of protein would be available as starting material. Because these antibodies did not produce signals on Western blots, which made it impossible to enrich the antigens by electrophoretic methods, we did not attempt their purification. However, the specific localization of these proteins makes them highly interesting and calls for their further characterization, as they may play a highly specialized role in the development and/or function of the neural circuits they are present in. The purification and identification of such low expression proteins would need novel methods of enrichment of the stained structures.},
  subject      = {Taufliege},
  language  = {en}
}
@phdthesis{Duraphe2010,
  author    = {Duraphe, Prashant},
  title     = {Identification and characterization of AUM, a novel human tyrosine phosphatase},
  url       = {http://nbn-resolving.de/urn:nbn:de:bvb:20-opus-44256},
  school      = {Universit{\"a}t W{\"u}rzburg},
  year      = {2010},
  abstract  = {Protein Phosphatasen werden aufgrund der Aminos{\"a}uresequenzen ihrer aktiven Zentren in drei große Familien unterteilt. In einer neu entdeckten Familie von Phosphatasen ist das aktive Zentrum durch die Sequenz DXDX(T/V) charakterisiert. Diese Aspartat-abh{\"a}ngigen Phosphatasen geh{\"o}ren zu der Superfamilie der Hydrolasen vom Haloazid Dehalogenase(HAD)-Typ, einer evolution{\"a}r konservierten und ubiquit{\"a}r verbreiteten Enzymfamilie. Bislang konnten 58 menschliche HAD Enzyme durch Datenbankanalysen identifiziert werden. Ihre Funktionen sind jedoch nach wie vor nur rudiment{\"a}r verstanden. Im Rahmen dieser Arbeit wurde zun{\"a}chst das Komplement aller menschlichen HAD Phosphatasen durch Datenbank-Recherchen erfasst. Zusammen mit phylogenetischen Analysen gelang es, eine zum damaligen Zeitpunkt unbekannte, putative Phosphatase zu identifizieren, die eine vergleichsweise hohe Sequenz-Homologie zu der Zytoskelettregulierenden HAD Phosphatase Chronophin aufweist. Dieses neuartige Enzym wurde kloniert und mit biochemischen und zellbiologischen Methoden charakterisiert. Auf der Basis dieser Befunde bezeichnen wir dieses neuartige Protein als AUM (actin remodeling, ubiquitously expressed, magnesium-dependent HAD phosphatase).Mittels Northern blot, real-time PCR und Western blot Analysen konnte gezeigt werden, dass AUM in allen untersuchten menschlichen und murinen Geweben exprimiert wird. Die h{\"o}chste Expression konnte in Hodengewebe nachgewiesen werden. Durch immunohistochemische Untersuchungen konnte gezeigt werden, dass AUM spezifisch in reifenden Keimzellen mit einem Expressionsmaximum zum Zeitpunkt der Spermiogenese exprimiert wird. Um die Substratpr{\"a}ferenz von AUM zu charakterisieren, wurde zun{\"a}chst ein peptidbasierter in vitro Phosphatase-Substrat-Screen durchgef{\"u}hrt. Hierbei wurden 720 aus menschlichen Phosphoproteinen abgeleitete Phosphopeptide untersucht. Interessanterweise dephosphorylierte AUM ausschließlich Phosphotyrosin (pTyr)-enthaltende Peptide. Nur 17 pTyr-Peptide (~2\% aller untersuchten Peptide) fungierten als AUM-Substrate. Diese Daten legen eine hohe Substratspezifit{\"a}t von AUM nahe. Zu den putativen AUM Substraten geh{\"o}ren Proteine, die in die Dynamik der Zytoskelett-Reorganisation sowie in Tyrosin Kinasevermittelte Signalwege eingebunden sind. In {\"U}bereinstimmung mit den Ergebnissen dieses Phosphopeptid-Screens konnte mittels Phosphatase overlay assays sowie in Zellextrakten aus Pervanadat-behandelten HeLa Zellen demonstriert werden, dass AUM eine begrenzte Anzahl Tyrosin-phosphorylierter Proteinen dephosphorylieren kann.In zellul{\"a}ren Untersuchungen wurde die m{\"o}gliche Rolle von AUM im Rahmen der durch den epidermalen Wachstumsfaktor (EGF) ausgel{\"o}sten Tyrosin-Phosphorylierung in einer Spermatogonien Zelllinie (GC-1 spg-Zellen) analysiert. So konnte nachgewiesen werden, dass die {\"U}berexpression von AUM zu einer moderaten Abnahme Tyrosin phosphorylierter Proteine nach EGF-Stimulation f{\"u}hrte. Im Gegensatz dazu l{\"o}ste jedoch die durch RNAInterferenz vermittelte Depletion von endogenem AUM einen robusten Anstieg Tyrosinphosphorylierter Proteine aus, zu denen auch der EGF-Rezeptor selbst z{\"a}hlt. Zus{\"a}tzlich zu dem EGF-Rezeptor wurde die Src-Kinase im Zuge des Phosphopeptid- Screens als m{\"o}gliches AUM Substrat identifiziert. Daher wurden in vitro Kinase/Phosphatase-Assays mit gereinigtem Src und AUM durchgef{\"u}hrt. Mit diesem Ansatz konnte erstmals gezeigt werden, dass AUM in der Lage ist, die Src-Kinase zu aktivieren, w{\"a}hrend Src AUM phosphoryliert und die AUM Phosphatase-Aktivit{\"a}t blockiert. Diese Ergebnisse deuten auf eine gekoppelte, wechselseitige Regulation von AUM und Src hin. Obwohl die Details dieser Regulation derzeit noch unklar sind, zeigen unsere initialen Ergebnisse, dass AUM die Src-Aktivit{\"a}t unabh{\"a}ngig von seiner Phosphatase Aktivit{\"a}t steigert, w{\"a}hrend Src die AUM Phosphatase-Aktivit{\"a}t Kinase-abh{\"a}ngig vermindert. Auf zellul{\"a}rer Ebene sind AUM-depletierte Zellen durch Ver{\"a}nderungen der Aktin- Zytoskelett-Dynamik und der Zelladh{\"a}sion charakterisiert. So weisen AUM-defiziente Zellen stabilisierte Aktin Streßfasern und vergr{\"o}ßerte fokale Adh{\"a}sionen auf. Weiterhin sind AUMdepletierte Zellen durch ein beschleunigtes spreading auf Fibronektin gekennzeichnet. Wir haben mit AUM ein bisher nicht beschriebenes Mitglied der Familie Aspartat-abh{\"a}ngiger Phosphatasen entdeckt. In dieser Arbeit ist es gelungen, AUM phylogenetisch, biochemisch und zellbiologisch zu charakterisieren. Unsere Ergebnisse legen nahe, dass AUM einen wichtigen, neuartigen Regulator der Src-vermittelten Zytoskelett-Dynamik im Rahmen der Zelladh{\"a}sion und Migration darstellt.},
  subject      = {Tyrosin},
  language  = {en}
}