TY - JOUR A1 - Thein, Marcus A1 - Bonde, Mari A1 - Bunikis, Ignas A1 - Denker, Katrin A1 - Sickmann, Albert A1 - Bergström, Sven A1 - Benz, Roland T1 - DipA, a Pore-Forming Protein in the Outer Membrane of Lyme Disease Spirochetes Exhibits Specificity for the Permeation of Dicarboxylates N2 - Lyme disease Borreliae are highly dependent on the uptake of nutrients provided by their hosts. Our study describes the identification of a 36 kDa protein that functions as putative dicarboxylate-specific porin in the outer membrane of Lyme disease Borrelia. The protein was purified by hydroxyapatite chromatography from Borrelia burgdorferi B31 and designated as DipA, for dicarboxylate-specific porin A. DipA was partially sequenced, and corresponding genes were identified in the genomes of B. burgdorferi B31, Borrelia garinii PBi and Borrelia afzelii PKo. DipA exhibits high homology to the Oms38 porins of relapsing fever Borreliae. B. burgdorferi DipA was characterized using the black lipid bilayer assay. The protein has a singlechannel conductance of 50 pS in 1 M KCl, is slightly selective for anions with a permeability ratio for cations over anions of 0.57 in KCl and is not voltage-dependent. The channel could be partly blocked by different di- and tricarboxylic anions. Particular high stability constants up to about 28,000 l/mol (in 0.1 M KCl) were obtained among the 11 tested anions for oxaloacetate, 2-oxoglutarate and citrate. The results imply that DipA forms a porin specific for dicarboxylates which may play an important role for the uptake of specific nutrients in different Borrelia species. KW - Medizin Y1 - 2012 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-75809 ER - TY - JOUR A1 - Plum, Sarah A1 - Eggers, Britta A1 - Helling, Stefan A1 - Stepath, Markus A1 - Theiss, Carsten A1 - Leite, Renata E. P. A1 - Molina, Mariana A1 - Grinberg, Lea T. A1 - Riederer, Peter A1 - Gerlach, Manfred A1 - May, Caroline A1 - Marcus, Katrin T1 - Proteomic characterization of synaptosomes from human substantia nigra indicates altered mitochondrial translation in Parkinson's disease JF - Cells N2 - The pathological hallmark of Parkinson's disease (PD) is the loss of neuromelanin-containing dopaminergic neurons within the substantia nigra pars compacta (SNpc). Additionally, numerous studies indicate an altered synaptic function during disease progression. To gain new insights into the molecular processes underlying the alteration of synaptic function in PD, a proteomic study was performed. Therefore, synaptosomes were isolated by density gradient centrifugation from SNpc tissue of individuals at advanced PD stages (N = 5) as well as control subjects free of pathology (N = 5) followed by mass spectrometry-based analysis. In total, 362 proteins were identified and assigned to the synaptosomal core proteome. This core proteome comprised all proteins expressed within the synapses without regard to data analysis software, gender, age, or disease. The differential analysis between control subjects and PD cases revealed that CD9 antigen was overrepresented and fourteen proteins, among them Thymidine kinase 2 (TK2), mitochondrial, 39S ribosomal protein L37, neurolysin, and Methionine-tRNA ligase (MARS2) were underrepresented in PD suggesting an alteration in mitochondrial translation within synaptosomes. KW - synaptosomes KW - proteomics KW - Parkinson's disease KW - substantia nigra pars compacta KW - mitochondrial pathology KW - mitochondrial translation Y1 - 2020 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-219978 SN - 2073-4409 VL - 9 IS - 12 ER - TY - JOUR A1 - Detomas, Mario A1 - Ritzel, Katrin A1 - Nasi-Kordhishti, Isabella A1 - Wolfsberger, Stefan A1 - Quinkler, Marcus A1 - Losa, Marco A1 - Tröger, Viola A1 - Kroiss, Matthias A1 - Fassnacht, Martin A1 - Vila, Greisa A1 - Honegger, Jürgen Bernd A1 - Reincke, Martin A1 - Deutschbein, Timo T1 - Outcome of CRH stimulation test and overnight 8 mg dexamethasone suppression test in 469 patients with ACTH-dependent Cushing’s syndrome JF - Frontiers in Endocrinology N2 - Objective To evaluate diagnostic accuracy of the corticotropin-releasing hormone (CRH) stimulation test and the overnight 8 mg dexamethasone suppression test (DST) for the differentiation of Cushing’s disease (CD) and ectopic Cushing’s syndrome (ECS). Methods Retrospective study in 6 European centers. Inclusion criteria: patients with a) overt adrenocorticotropin (ACTH)-dependent Cushing’s syndrome at the time of dynamic testing, b) histopathological confirmed tumors and/or c) postoperative biochemical remission and/or adrenal insufficiency. Optimal cut-offs were calculated via receiver operating characteristic (ROC) analysis using CD as reference. Results 469 patients were analyzed [78% females; median age 43 years (IQR 19)]. CRH test and overnight 8 mg DST were performed in 420 [CD, n=394 (94%); ECS, n=26 (6%)] and 237 patients [228 CD (96%), 9 ECS (4%)]. Both tests were performed in 205 patients (44%). The post-CRH %-increase at 30 minutes of both ACTH (cut-off ≥31%, sensitivity 83%, specificity 85%, AUC 0.81) and cortisol (cut-off ≥12%, sensitivity 82%, specificity 89%, AUC 0.86) discriminated best between CD and ECS. A test duration of >60 minutes did not improve diagnostic performance of the CRH test. The optimal cortisol cut-off for the %-suppression during the 8 mg DST was ≥55% (sensitivity 80%, specificity 78%, AUC 0.75). Conclusion The CRH test has equivalent sensitivity but higher specificity than the 8 mg DST and is therefore the test of first choice. The diagnostic outcome of ACTH and cortisol is well comparable, however, sampling beyond 60 minutes post-CRH does not provide diagnostic benefits. KW - ACTH KW - Cushing's disease KW - Cushing’s syndrome KW - CRH stimulation test KW - diagnosis KW - ectopic KW - endogenous hypercortisolism KW - high dose dexamethasone suppression test Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-289450 SN - 1664-2392 VL - 13 ER - TY - JOUR A1 - Plum, Sarah A1 - Steinbach, Simone A1 - Attems, Johannes A1 - Keers, Sharon A1 - Riederer, Peter A1 - Gerlach, Manfred A1 - May, Caroline A1 - Marcus, Katrin T1 - Proteomic characterization of neuromelanin granules isolated from human substantia nigra by laser-microdissection JF - Scientific Reports N2 - Neuromelanin is a complex polymer pigment found primarily in the dopaminergic neurons of human substantia nigra. Neuromelanin pigment is stored in granules including a protein matrix and lipid droplets. Neuromelanin granules are yet only partially characterised regarding their structure and function. To clarify the exact function of neuromelanin granules in humans, their enrichment and in-depth characterization from human substantia nigra is necessary. Previously published global proteome studies of neuromelanin granules in human substantia nigra required high tissue amounts. Due to the limited availability of human brain tissue we established a new method based on laser microdissection combined with mass spectrometry for the isolation and analysis of neuromelanin granules. With this method it is possible for the first time to isolate a sufficient amount of neuromelanin granules for global proteomics analysis from ten 10 μm tissue sections. In total 1,000 proteins were identified associated with neuromelanin granules. More than 68% of those proteins were also identified in previously performed studies. Our results confirm and further extend previously described findings, supporting the connection of neuromelanin granules to iron homeostasis and lysosomes or endosomes. Hence, this method is suitable for the donor specific enrichment and proteomic analysis of neuromelanin granules. KW - neuromelanin KW - substantia nigra KW - pigment KW - granules Y1 - 2016 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-167507 VL - 6 IS - 37139 ER - TY - JOUR A1 - Wulf, Maximilian A1 - Barkovits, Katalin A1 - Schork, Karin A1 - Eisenacher, Martin A1 - Riederer, Peter A1 - Gerlach, Manfred A1 - Eggers, Britta A1 - Marcus, Katrin T1 - The proteome of neuromelanin granules in dementia with Lewy bodies JF - Cells N2 - Neuromelanin granules (NMGs) are organelle-like structures present in the human substantia nigra pars compacta. In addition to neuromelanin, NMGs contain proteins, lipids and metals. As NMG-containing dopaminergic neurons are preferentially lost in Parkinson’s disease and dementia with Lewy bodies (DLB), it is assumed that NMGs may play a role in neurodegenerative processes. Until now, this role is not completely understood and needs further investigation. We therefore set up an exploratory proteomic study to identify differences in the proteomic profile of NMGs from DLB patients (n = 5) compared to healthy controls (CTRL, n = 5). We applied a laser microdissection and mass-spectrometry-based approach, in which we used targeted mass spectrometric experiments for validation. In NMG-surrounding (SN\(_{Surr.}\)) tissue of DLB patients, we found evidence for ongoing oxidative damage and an impairment of protein degradation. As a potentially disease-related mechanism, we found α-synuclein and protein S100A9 to be enriched in NMGs of DLB cases, while the abundance of several ribosomal proteins was significantly decreased. As S100A9 is known to be able to enhance the formation of toxic α-synuclein fibrils, this finding points towards an involvement of NMGs in pathogenesis, however the exact role of NMGs as either neuroprotective or neurotoxic needs to be further investigated. Nevertheless, our study provides evidence for an impairment of protein degradation, ongoing oxidative damage and accumulation of potentially neurotoxic protein aggregates to be central mechanisms of neurodegeneration in DLB. KW - neuromelanin granules KW - neurodegeneration KW - dementia with Lewy bodies KW - proteomics KW - stress granules KW - substantia nigra pars compacta Y1 - 2022 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:bvb:20-opus-297465 SN - 2073-4409 VL - 11 IS - 22 ER -