TY  - JOUR
A1  - Lombardi, Jolina
A1  - Mayer, Benjamin
A1  - Semler, Elisa
A1  - Anderl‐Straub, Sarah
A1  - Uttner, Ingo
A1  - Kassubek, Jan
A1  - Diehl‐Schmid, Janine
A1  - Danek, Adrian
A1  - Levin, Johannes
A1  - Fassbender, Klaus
A1  - Fliessbach, Klaus
A1  - Schneider, Anja
A1  - Huppertz, Hans‐Jürgen
A1  - Jahn, Holger
A1  - Volk, Alexander
A1  - Kornhuber, Johannes
A1  - Landwehrmeyer, Bernhard
A1  - Lauer, Martin
A1  - Prudlo, Johannes
A1  - Wiltfang, Jens
A1  - Schroeter, Matthias L.
A1  - Ludolph, Albert
A1  - Otto, Markus
T1  - Quantifying progression in primary progressive aphasia with structural neuroimaging
JF  - Alzheimer's & Dementia
N2  - Introduction
The term primary progressive aphasia (PPA) sums up the non‐fluent (nfv), the semantic (sv), and the logopenic (lv) variant. Up to now, there is only limited data available concerning magnetic resonance imaging volumetry to monitor disease progression.
Methods
Structural brain imaging and an extensive assessment were applied at baseline and up to 4‐year(s) follow‐up in 269 participants. With automated atlas‐based volumetry 56 brain regions were assessed. Atrophy progression served to calculate sample sizes for therapeutic trials.
Results
At baseline highest atrophy appeared in parts of the left frontal lobe for nfvPPA (–17%) and of the left temporal lobe for svPPA (–34%) and lvPPA (–24%). Severest progression within 1‐year follow‐up occurred in the basal ganglia in nfvPPA (–7%), in the hippocampus/amygdala in svPPA (–9%), and in (medial) temporal regions in lvPPA (–6%).
Conclusion
PPA presents as a left‐dominant, mostly gray matter sensitive disease with considerable atrophy at baseline that proceeds variant‐specific.
KW  - atlas‐based volumetry
KW  - disease progression
KW  - frontotemporal dementia
KW  - longitudinal magnetic resonance imaging
KW  - primary progressive aphasia
KW  - sample size calculation
Y1  - 2021
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-262605
VL  - 17
IS  - 10
SP  - 1595
EP  - 1609
ER  - 
TY  - JOUR
A1  - Friedrich, Maximilian U.
A1  - Schneider, Erich
A1  - Buerklein, Miriam
A1  - Taeger, Johannes
A1  - Hartig, Johannes
A1  - Volkmann, Jens
A1  - Peach, Robert
A1  - Zeller, Daniel
T1  - Smartphone video nystagmography using convolutional neural networks: ConVNG
JF  - Journal of Neurology
N2  - Background
Eye movement abnormalities are commonplace in neurological disorders. However, unaided eye movement assessments lack granularity. Although videooculography (VOG) improves diagnostic accuracy, resource intensiveness precludes its broad use. To bridge this care gap, we here validate a framework for smartphone video-based nystagmography capitalizing on recent computer vision advances.

Methods
A convolutional neural network was fine-tuned for pupil tracking using > 550 annotated frames: ConVNG. In a cross-sectional approach, slow-phase velocity of optokinetic nystagmus was calculated in 10 subjects using ConVNG and VOG. Equivalence of accuracy and precision was assessed using the “two one-sample t-test” (TOST) and Bayesian interval-null approaches. ConVNG was systematically compared to OpenFace and MediaPipe as computer vision (CV) benchmarks for gaze estimation.

Results
ConVNG tracking accuracy reached 9–15% of an average pupil diameter. In a fully independent clinical video dataset, ConVNG robustly detected pupil keypoints (median prediction confidence 0.85). SPV measurement accuracy was equivalent to VOG (TOST p < 0.017; Bayes factors (BF) > 24). ConVNG, but not MediaPipe, achieved equivalence to VOG in all SPV calculations. Median precision was 0.30°/s for ConVNG, 0.7°/s for MediaPipe and 0.12°/s for VOG. ConVNG precision was significantly higher than MediaPipe in vertical planes, but both algorithms’ precision was inferior to VOG.

Conclusions
ConVNG enables offline smartphone video nystagmography with an accuracy comparable to VOG and significantly higher precision than MediaPipe, a benchmark computer vision application for gaze estimation. This serves as a blueprint for highly accessible tools with potential to accelerate progress toward precise and personalized Medicine.
KW  - digital medicine
KW  - nystagmus
KW  - eye movement disorders
KW  - videooculography
KW  - computer vision
KW  - telemedicine
KW  - precision medicine
Y1  - 2023
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-324526
VL  - 270
IS  - 5
ER  - 
TY  - JOUR
A1  - Semler, Elisa
A1  - Anderl-Straub, Sarah
A1  - Uttner, Ingo
A1  - Diehl-Schmid, Janine
A1  - Danek, Adrian
A1  - Einsiedler, Beate
A1  - Fassbender, Klaus
A1  - Fliessbach, Klaus
A1  - Huppertz, Hans-Jürgen
A1  - Jahn, Holger
A1  - Kornhuber, Johannes
A1  - Landwehrmeyer, Bernhard
A1  - Lauer, Martin
A1  - Muche, Rainer
A1  - Prudlo, Johannes
A1  - Schneider, Anja
A1  - Schroeter, Matthias L.
A1  - Ludolph, Albert C.
A1  - Otto, Markus
T1  - A language-based sum score for the course and therapeutic intervention in primary progressive aphasia
JF  - Alzheimer's Research & Therapy
N2  - Background
With upcoming therapeutic interventions for patients with primary progressive aphasia (PPA), instruments for the follow-up of patients are needed to describe disease progression and to evaluate potential therapeutic effects. So far, volumetric brain changes have been proposed as clinical endpoints in the literature, but cognitive scores are still lacking. This study followed disease progression predominantly in language-based performance within 1 year and defined a PPA sum score which can be used in therapeutic interventions.

Methods
We assessed 28 patients with nonfluent variant PPA, 17 with semantic variant PPA, 13 with logopenic variant PPA, and 28 healthy controls in detail for 1 year. The most informative neuropsychological assessments were combined to a sum score, and associations between brain atrophy were investigated followed by a sample size calculation for clinical trials.

Results
Significant absolute changes up to 20% in cognitive tests were found after 1 year. Semantic and phonemic word fluency, Boston Naming Test, Digit Span, Token Test, AAT Written language, and Cookie Test were identified as the best markers for disease progression. These tasks provide the basis of a new PPA sum score. Assuming a therapeutic effect of 50% reduction in cognitive decline for sample size calculations, a number of 56 cases is needed to find a significant treatment effect. Correlations between cognitive decline and atrophy showed a correlation up to r = 0.7 between the sum score and frontal structures, namely the superior and inferior frontal gyrus, as well as with left-sided subcortical structures.

Conclusion
Our findings support the high performance of the proposed sum score in the follow-up of PPA and recommend it as an outcome measure in intervention studies.
KW  - frontotemporal dementia
KW  - cognitive neuropsychology in dementia
KW  - assessment of cognitive disorders/dementia
KW  - volumetric MRI
KW  - aphasia
Y1  - 2018
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-236277
VL  - 10
ER  - 
TY  - JOUR
A1  - Albrecht, Franziska
A1  - Mueller, Karsten
A1  - Ballarini, Tommaso
A1  - Lampe, Leonie
A1  - Diehl-Schmid, Janine
A1  - Fassbender, Klaus
A1  - Fliessbach, Klaus
A1  - Jahn, Holger
A1  - Jech, Robert
A1  - Kassubek, Jan
A1  - Kornhuber, Johannes
A1  - Landwehrmeyer, Bernhard
A1  - Lauer, Martin
A1  - Ludolph, Albert C.
A1  - Lyros, Epameinondas
A1  - Prudlo, Johannes
A1  - Schneider, Anja
A1  - Synofzik, Matthis
A1  - Wiltfang, Jens
A1  - Danek, Adrian
A1  - Otto, Markus
A1  - Schroeter, Matthias L.
T1  - Unraveling corticobasal syndrome and alien limb syndrome with structural brain imaging
JF  - Cortex
N2  - Alien limb phenomenon is a rare syndrome associated with a feeling of non-belonging and disowning toward one's limb. In contrast, anarchic limb phenomenon leads to involuntary but goal-directed movements. Alien/anarchic limb phenomena are frequent in corticobasal syndrome (CBS), an atypical parkinsonian syndrome characterized by rigidity, akinesia, dystonia, cortical sensory deficit, and apraxia. The structure function relationship of alien/anarchic limb was investigated in multi centric structural magnetic resonance imaging (MRI) data. Whole-group and single subject comparisons were made in 25 CBS and eight CBS-alien/anarchic limb patients versus controls. Support vector machine was used to see if CBS with and without alien/anarchic limb could be distinguished by structural MRI patterns. Whole-group comparison of CBS versus controls revealed asymmetric frontotemporal atrophy. CBS with alien/anarchic limb syndrome versus controls showed frontoparietal atrophy including the supplementary motor area contralateral to the side of the affected limb. Exploratory analysis identified frontotemporal regions encompassing the pre-/and postcentral gyrus as compromised in CBS with alien limb syndrome. Classification of CBS patients yielded accuracies of 79%. CBS-alien/anarchic limb syndrome was differentiated from CBS patients with an accuracy of 81%. Predictive differences were found in the cingulate gyrus spreading to frontomedian cortex, postcentral gyrus, and temporoparietoocipital regions. We present the first MRI-based group analysis on CBS-alien/anarchic limb. Results pave the way for individual clinical syndrome prediction and allow understanding the underlying neurocognitive architecture. (C) 2019 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
KW  - Alien limb syndrome
KW  - Anarchic limb syndrome
KW  - Corticobasal syndrome
KW  - Diagnosis prediction
KW  - Support vector machine
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-221040
VL  - 117
ER  - 
TY  - JOUR
A1  - El-Helou, Sabine M.
A1  - Biegner, Anika-Kerstin
A1  - Bode, Sebastian
A1  - Ehl, Stephan R.
A1  - Heeg, Maximilian
A1  - Maccari, Maria E.
A1  - Ritterbusch, Henrike
A1  - Speckmann, Carsten
A1  - Rusch, Stephan
A1  - Scheible, Raphael
A1  - Warnatz, Klaus
A1  - Atschekzei, Faranaz
A1  - Beider, Renata
A1  - Ernst, Diana
A1  - Gerschmann, Stev
A1  - Jablonka, Alexandra
A1  - Mielke, Gudrun
A1  - Schmidt, Reinhold E.
A1  - Schürmann, Gesine
A1  - Sogkas, Georgios
A1  - Baumann, Ulrich H.
A1  - Klemann, Christian
A1  - Viemann, Dorothee
A1  - Bernuth, Horst von
A1  - Krüger, Renate
A1  - Hanitsch, Leif G.
A1  - Scheibenbogen, Carmen M.
A1  - Wittke, Kirsten
A1  - Albert, Michael H.
A1  - Eichinger, Anna
A1  - Hauck, Fabian
A1  - Klein, Christoph
A1  - Rack-Hoch, Anita
A1  - Sollinger, Franz M.
A1  - Avila, Anne
A1  - Borte, Michael
A1  - Borte, Stephan
A1  - Fasshauer, Maria
A1  - Hauenherm, Anja
A1  - Kellner, Nils
A1  - Müller, Anna H.
A1  - Ülzen, Anett
A1  - Bader, Peter
A1  - Bakhtiar, Shahrzad
A1  - Lee, Jae-Yun
A1  - Heß, Ursula
A1  - Schubert, Ralf
A1  - Wölke, Sandra
A1  - Zielen, Stefan
A1  - Ghosh, Sujal
A1  - Laws, Hans-Juergen
A1  - Neubert, Jennifer
A1  - Oommen, Prasad T.
A1  - Hönig, Manfred
A1  - Schulz, Ansgar
A1  - Steinmann, Sandra
A1  - Klaus, Schwarz
A1  - Dückers, Gregor
A1  - Lamers, Beate
A1  - Langemeyer, Vanessa
A1  - Niehues, Tim
A1  - Shai, Sonu
A1  - Graf, Dagmar
A1  - Müglich, Carmen
A1  - Schmalzing, Marc T.
A1  - Schwaneck, Eva C.
A1  - Tony, Hans-Peter
A1  - Dirks, Johannes
A1  - Haase, Gabriele
A1  - Liese, Johannes G.
A1  - Morbach, Henner
A1  - Foell, Dirk
A1  - Hellige, Antje
A1  - Wittkowski, Helmut
A1  - Masjosthusmann, Katja
A1  - Mohr, Michael
A1  - Geberzahn, Linda
A1  - Hedrich, Christian M.
A1  - Müller, Christiane
A1  - Rösen-Wolff, Angela
A1  - Roesler, Joachim
A1  - Zimmermann, Antje
A1  - Behrends, Uta
A1  - Rieber, Nikolaus
A1  - Schauer, Uwe
A1  - Handgretinger, Rupert
A1  - Holzer, Ursula
A1  - Henes, Jörg
A1  - Kanz, Lothar
A1  - Boesecke, Christoph
A1  - Rockstroh, Jürgen K.
A1  - Schwarze-Zander, Carolynne
A1  - Wasmuth, Jan-Christian
A1  - Dilloo, Dagmar
A1  - Hülsmann, Brigitte
A1  - Schönberger, Stefan
A1  - Schreiber, Stefan
A1  - Zeuner, Rainald
A1  - Ankermann, Tobias
A1  - Bismarck, Philipp von
A1  - Huppertz, Hans-Iko
A1  - Kaiser-Labusch, Petra
A1  - Greil, Johann
A1  - Jakoby, Donate
A1  - Kulozik, Andreas E.
A1  - Metzler, Markus
A1  - Naumann-Bartsch, Nora
A1  - Sobik, Bettina
A1  - Graf, Norbert
A1  - Heine, Sabine
A1  - Kobbe, Robin
A1  - Lehmberg, Kai
A1  - Müller, Ingo
A1  - Herrmann, Friedrich
A1  - Horneff, Gerd
A1  - Klein, Ariane
A1  - Peitz, Joachim
A1  - Schmidt, Nadine
A1  - Bielack, Stefan
A1  - Groß-Wieltsch, Ute
A1  - Classen, Carl F.
A1  - Klasen, Jessica
A1  - Deutz, Peter
A1  - Kamitz, Dirk
A1  - Lassy, Lisa
A1  - Tenbrock, Klaus
A1  - Wagner, Norbert
A1  - Bernbeck, Benedikt
A1  - Brummel, Bastian
A1  - Lara-Villacanas, Eusebia
A1  - Münstermann, Esther
A1  - Schneider, Dominik T.
A1  - Tietsch, Nadine
A1  - Westkemper, Marco
A1  - Weiß, Michael
A1  - Kramm, Christof
A1  - Kühnle, Ingrid
A1  - Kullmann, Silke
A1  - Girschick, Hermann
A1  - Specker, Christof
A1  - Vinnemeier-Laubenthal, Elisabeth
A1  - Haenicke, Henriette
A1  - Schulz, Claudia
A1  - Schweigerer, Lothar
A1  - Müller, Thomas G.
A1  - Stiefel, Martina
A1  - Belohradsky, Bernd H.
A1  - Soetedjo, Veronika
A1  - Kindle, Gerhard
A1  - Grimbacher, Bodo
T1  - The German national registry of primary immunodeficiencies (2012-2017)
JF  - Frontiers in Immunology
N2  - Introduction: The German PID-NET registry was founded in 2009, serving as the first national registry of patients with primary immunodeficiencies (PID) in Germany. It is part of the European Society for Immunodeficiencies (ESID) registry. The primary purpose of the registry is to gather data on the epidemiology, diagnostic delay, diagnosis, and treatment of PIDs. 

Methods: Clinical and laboratory data was collected from 2,453 patients from 36 German PID centres in an online registry. Data was analysed with the software Stata® and Excel. 

Results: The minimum prevalence of PID in Germany is 2.72 per 100,000 inhabitants. Among patients aged 1-25, there was a clear predominance of males. The median age of living patients ranged between 7 and 40 years, depending on the respective PID. Predominantly antibody disorders were the most prevalent group with 57% of all 2,453 PID patients (including 728 CVID patients). A gene defect was identified in 36% of patients. Familial cases were observed in 21% of patients. The age of onset for presenting symptoms ranged from birth to late adulthood (range 0-88 years). Presenting symptoms comprised infections (74%) and immune dysregulation (22%). Ninety-three patients were diagnosed without prior clinical symptoms. Regarding the general and clinical diagnostic delay, no PID had undergone a slight decrease within the last decade. However, both, SCID and hyper IgE-syndrome showed a substantial improvement in shortening the time between onset of symptoms and genetic diagnosis. Regarding treatment, 49% of all patients received immunoglobulin G (IgG) substitution (70%-subcutaneous; 29%-intravenous; 1%-unknown). Three-hundred patients underwent at least one hematopoietic stem cell transplantation (HSCT). Five patients had gene therapy. 

Conclusion: The German PID-NET registry is a precious tool for physicians, researchers, the pharmaceutical industry, politicians, and ultimately the patients, for whom the outcomes will eventually lead to a more timely diagnosis and better treatment.
KW  - registry for primary immunodeficiency
KW  - primary immunodeficiency (PID)
KW  - German PID-NET registry
KW  - PID prevalence
KW  - European Society for Immunodeficiencies (ESID)
KW  - IgG substitution therapy
KW  - CVID
Y1  - 2019
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-226629
VL  - 10
ER  - 
TY  - JOUR
A1  - Seydelmann, Nora
A1  - Liu, Dan
A1  - Krämer, Johannes
A1  - Drechsler, Christiane
A1  - Hu, Kai
A1  - Nordbeck, Peter
A1  - Schneider, Andreas
A1  - Störk, Stefan
A1  - Bijnens, Bart
A1  - Ertl, Georg
A1  - Wanner, Christoph
A1  - Weidemann, Frank
T1  - High-Sensitivity Troponin: A Clinical Blood Biomarker for Staging Cardiomyopathy in Fabry Disease
JF  - Journal of the American Heart Association
N2  - Background
High‐sensitivity troponin (hs‐TNT), a biomarker of myocardial damage, might be useful for assessing fibrosis in Fabry cardiomyopathy. We performed a prospective analysis of hs‐TNT as a biomarker for myocardial changes in Fabry patients and a retrospective longitudinal follow‐up study to assess longitudinal hs‐TNT changes relative to fibrosis and cardiomyopathy progression.

Methods and Results
For the prospective analysis, hs‐TNT from 75 consecutive patients with genetically confirmed Fabry disease was analyzed relative to typical Fabry‐associated echocardiographic findings and total myocardial fibrosis as measured by late gadolinium enhancement (LE) on magnetic resonance imaging. Longitudinal data (3.9±2.0 years), including hs‐TNT, LE, and echocardiographic findings from 58 Fabry patients, were retrospectively collected. Hs‐TNT level positively correlated with LE (linear correlation coefficient, 0.72; odds ratio, 32.81 [95% CI, 3.56–302.59]; P=0.002); patients with elevated baseline hs‐TNT (>14 ng/L) showed significantly increased LE (median: baseline, 1.9 [1.1–3.3] %; follow‐up, 3.2 [2.3–4.9] %; P<0.001) and slightly elevated hs‐TNT (baseline, 44.7 [30.1–65.3] ng/L; follow‐up, 49.1 [27.6–69.5] ng/L; P=0.116) during follow‐up. Left ventricular wall thickness and EF of patients with elevated hs‐TNT were decreased during follow‐up, indicating potential cardiomyopathy progression.

Conclusions
hs‐TNT is an accurate, easily accessible clinical blood biomarker for detecting replacement fibrosis in patients with Fabry disease and a qualified predictor of cardiomyopathy progression. Thus, hs‐TNT could be helpful for staging and follow‐up of Fabry patients.
KW  - biomarker
KW  - cardiomyopathy
KW  - fabry disease
KW  - myocardial fibrosis
KW  - troponin T
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-165682
VL  - 5
IS  - e002839
ER  - 
TY  - JOUR
A1  - Flegler, Andreas
A1  - Schneider, Michael
A1  - Prieschl, Johannes
A1  - Stevens, Ralph
A1  - Vinnay, Thomas
A1  - Mandel, Karl
T1  - Continuous flow synthesis and cleaning of nano layered double hydroxides and the potential of the route to adjust round or platelet nanoparticle morphology
JF  - RSC Advances
N2  - Here, we report a continuous flow synthesis of nano LDH, comprising a continuous precipitation process using static mixers and followed by an immediate cleaning process via a semi-continuous centrifuge to obtain the final product in one-go. Via this synthesis setup, it is possible to independently vary the concentrations of the reactants during precipitation and at the same time ensure constant reaction conditions and an immediate "quenching" of the precipitate due to "on the flow"-washing. We found that this paves the way to adjust the synthesis parameters in a way that the final morphology of the nano-LDH particles can be controlled to be either round or platelet-like.
KW  - MgAl LDH
KW  - nano LDH
KW  - static mixer
KW  - synthesis process
Y1  - 2016
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-191305
VL  - 6
IS  - 62
ER  - 
TY  - JOUR
A1  - Jockel-Schneider, Yvonne
A1  - Harks, Inga
A1  - Haubitz, Imme
A1  - Fickl, Stefan
A1  - Eigenthaler, Martin
A1  - Schlagenhauf, Ulrich
A1  - Baulmann, Johannes
T1  - Arterial Stiffness and Pulse Wave Reflection Are Increased in Patients Suffering from Severe Periodontitis
JF  - PLOS ONE
N2  - Aim: This single blind cross-sectional study compared the vascular health of subjects suffering from severe chronic periodontitis, severe aggressive periodontitis and periodontal healthy controls by evaluating pulse wave velocity (PWV), augmentation index (AIx) and pulse pressure amplification (PPA).
Material and Methods: In a total of 158 subjects, 92 suffering from severe periodontitis and 66 matched periodontal healthy controls, PWV, AIx, central and peripheral blood pressure were recorded using an oscillometric device (Arteriograph).
Results: Subjects suffering from severe chronic or aggressive periodontitis exhibited significantly higher PWV (p = 0.00004), higher AIx (p = 0.0049) and lower PPA (p = 0.028) than matched periodontal healthy controls.
Conclusions: The results of this study confirm the association between periodontal inflammation and increased cardiovascular risk shown by impaired vascular health in case of severe periodontitis. As impaired vascular health is a common finding in patients suffering from severe periodontal disease a concomitant routine cardiovascular evaluation may be advised.
KW  - periodontal diseases
KW  - diagnostic medicine
KW  - teeth
KW  - stiffness
KW  - reflection
KW  - periodontitis
KW  - blood pressure
KW  - hypertension
Y1  - 2014
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-119459
SN  - 1932-6203
VL  - 9
IS  - 8
ER  - 
TY  - THES
A1  - Schneider, Johannes
T1  - Functional diversification of membrane microdomains in Bacillus subtilis
T1  - Funktionale Diversifizierung von Membran-Mikrodomänen in Bacillus subtilis
N2  - Eukaryotic cells are considered as evolutionary complex organisms because they possess organelles that enable them to regulate the spatio-temporal organization of cellular processes. Spatio-temporal organization of signal transduction cascades occurs in eukaryotic cells via organization of membrane-associated microdomains or lipid rafts. Lipid rafts are nanoscale-sized domains in the plasma membrane that are constituted by a specific set of lipids and proteins and harbor a number of proteins related to signal transduction and trafficking. The integrity of lipid rafts is important for the assembly and functional coordination of a plethora of signaling networks and associated processes. This integrity is partially mediated by a chaperone protein called flotillin. Disruption of lipid raft integrity, for example via depletion or overproduction of flotillin, alters raft-associated signal transduction cascades and causes severe diseases like Alzheimer’s, Parkinson’s disease or cardiovascular disease.

It was traditionally assumed that a sophisticated compartmentalization of cellular processes like the one exhibited in lipid rafts was exclusive to eukaryotic cells and therefore, lipid rafts have been considered as a hallmark in the evolution of cellular complexity, suggesting that prokaryotic cells were too simple organisms to organize such sophisticated membrane platforms. However, it was recently discovered that bacteria are also able to organize Functional Membrane Microdomains (FMMs) in their cellular membrane that are able to organize and catalyze the functionality of many diverse cellular processes. These FMMs of bacterial membranes contain flotillin-like proteins which play important roles in the organization of FMM-associated cellular processes.

In this dissertation I describe the structural and biological significance of the existence of two distinct flotillin proteins, FloA and FloT, in the FMMs of the bacterial model Bacillus subtilis. Localization studies, proteomic data and transcriptomic analyses show that FloA and FloT are individual scaffold proteins that activate different regulatory programs during bacterial growth. Using the tractable bacterial model system, I show that the functionality of important regulatory proteins, like the protease FtsH or the signaling kinases KinC, PhoR and ResE, is linked to the activity of FMMs and that this is a direct consequence of the scaffold activity of the bacterial flotillins. FloA and FloT distribute heterogeneously along the FMMs of B. subtilis thereby generating a heterogeneous population of FMMs that compartmentalize different signal transduction cascades. Interestingly, diversification of FMMs does not occur randomly, but rather in a controlled spatio-temporal program to ensure the activation of given signaling networks at the right place and time during cell growth.
N2  - Eukaryotische Zellen werden als evolutionär komplexe Organismen betrachtet, weil sie Organellen besitzen, mit denen sie die raum-zeitliche Organisation von zellulären Prozessen steuern können. Die räumliche und zeitliche Organisation von Signalwegen in eukaryotischen Zellen erfolgt durch die Abgrenzung von membran-assoziierten Mikrodomänen oder Lipid Rafts. Lipid Rafts sind wenige Nanometer große Felder in der Plasmamembran, die aus einem spezifischen Set von Lipiden und Proteinen zusammengesetzt sind und eine Reihe von für die Signaltransduktion und den Proteintransfer erforderlichen Proteine enthalten. Die Integrität der Lipid Rafts ist wichtig um zahlreiche Signalwege und damit assoziierte Prozesse zu verbinden und funktional zu koordinieren. Diese Integrität wird zum Teil von einem Chaperon-Protein namens Flotillin vermittelt. Eine Beeinträchtigung der Integrität der Lipid Rafts, z.B. aufgrund eines Mangels an Flotillin oder einer Überproduktion von Flotillin, verändert Raft-assoziierte Signalwege und verursacht schwere Erkrankungen wie Alzheimer, Parkinson oder kardiovaskuläre Erkrankungen. 

	Bislang wurde angenommen, dass eine so anspruchsvolle Kompartimentierung zellulärer Prozesse wie im Falle der Lipid Rafts ausschließlich in eukaryotischen Zellen vorkommt. Lipid Rafts galten daher als Meilenstein in der Evolution der zellulären Komplexität und prokaryotische Zellen als zu einfache Organismen, um solch komplexe Plattformen in der Membran einzurichten. Vor kurzem wurde jedoch herausgefunden, dass Bakterien ebenfalls in der Lage sind, Funktionale Mikrodomänen in der Membran (FMMs) zu formen, die viele verschiedene zelluläre Prozesse organisieren und katalysieren können. Diese FMMs in bakteriellen Membranen enthalten Flotillin-ähnliche Proteine, die wichtige Aufgaben bei der Organisation von FMM-assoziierten Prozessen übernehmen. 

	In dieser Dissertation beschreibe ich die strukturelle und biologische Signifikanz des Vorkommens der beiden verschiedenen Flotillin-Proteine FloA und FloT in den FMMs des bakteriellen Modellorganismus Bacillus subtilis. Lokalisationsstudien, proteomische Daten und transkriptomische Analysen demonstrieren, dass FloA und FloT individuelle Gerüstproteine sind, die während des Bakterienwachstums verschiedene regulatorische Programme aktivieren. Mit Hilfe des zugänglichen bakteriellen Modellorganismus zeige ich, dass die Funktionsweise von wichtigen regulatorischen Proteinen, wie z.B. der Protease FtsH oder der Signalwegskinasen KinC, PhoR und ResE, an die Aktivität der FMMs gebunden ist, und dass dies eine direkte Folge der stützenden Tätigkeit der bakteriellen Flotilline ist. FloA und FloT sind unterschiedlich in den FMMs von B. subtilis verteilt, wodurch sie eine heterogene Population von FMMs erzeugen, die verschiedene Signalwege abgrenzen kann. Interessanterweise erfolgt die Diversifizierung der FMMs nicht zufällig, sondern durch ein räumlich und zeitlich kontrolliertes Programm, um die Aktivierung von bestimmten Signalwegen am richtigen Ort und zur richtigen Zeit während des Zellwachstums sicherzustellen.
KW  - Heubacillus
KW  - Plasmamembran
KW  - Diversifikation <Biologie>
KW  - FMMs
KW  - Bacillus subtilis
KW  - Flotillin
KW  - Lipid Rafts
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-127569
ER  - 
TY  - JOUR
A1  - Schneider, Johannes
A1  - Klein, Teresa
A1  - Mielich-Süss, Benjamin
A1  - Koch, Gudrun
A1  - Franke, Christian
A1  - Kuipers, Oskar P.
A1  - Kovács, Ákos T.
A1  - Sauer, Markus
A1  - Lopez, Daniel
T1  - Spatio-temporal Remodeling of Functional Membrane Microdomains Organizes the Signaling Networks of a Bacterium
JF  - PLoS Genetics
N2  - Lipid rafts are membrane microdomains specialized in the regulation of numerous cellular processes related to membrane organization, as diverse as signal transduction, protein sorting, membrane trafficking or pathogen invasion. It has been proposed that this functional diversity would require a heterogeneous population of raft domains with varying compositions. However, a mechanism for such diversification is not known. We recently discovered that bacterial membranes organize their signal transduction pathways in functional membrane microdomains (FMMs) that are structurally and functionally similar to the eukaryotic lipid rafts. In this report, we took advantage of the tractability of the prokaryotic model Bacillus subtilis to provide evidence for the coexistence of two distinct families of FMMs in bacterial membranes, displaying a distinctive distribution of proteins specialized in different biological processes. One family of microdomains harbors the scaffolding flotillin protein FloA that selectively tethers proteins specialized in regulating cell envelope turnover and primary metabolism. A second population of microdomains containing the two scaffolding flotillins, FloA and FloT, arises exclusively at later stages of cell growth and specializes in adaptation of cells to stationary phase. Importantly, the diversification of membrane microdomains does not occur arbitrarily. We discovered that bacterial cells control the spatio-temporal remodeling of microdomains by restricting the activation of FloT expression to stationary phase. This regulation ensures a sequential assembly of functionally specialized membrane microdomains to strategically organize signaling networks at the right time during the lifespan of a bacterium.
KW  - membrane proteins
KW  - gene expression
KW  - bacillus subtilis
KW  - fluorescence microscopy
KW  - cell fusion
KW  - signal transduction
KW  - gene regulation
KW  - lipids
Y1  - 2015
U6  - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-125577
VL  - 11
IS  - 4
ER  -