Angela Schlipp

Publications (5) View all

• Article: FRET measurements of intracellular cAMP concentrations and cAMP analog permeability in intact cells.

  Sebastian Börner, Frank Schwede, Angela Schlipp, Filip Berisha, Davide Calebiro, Martin J Lohse, Viacheslav O Nikolaev
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  ABSTRACT: Real-time measurements of second messengers in living cells, such as cAMP, are usually performed by ratiometric fluorescence resonance energy transfer (FRET) imaging. However, correct calibration of FRET ratios, accurate calculations of absolute cAMP levels and actual permeabilities of different cAMP analogs have been challenging. Here we present a protocol that allows precise measurements of cAMP concentrations and kinetics by expressing FRET-based cAMP sensors in cells and modulating them with an inhibitor of adenylyl cyclase activity and a cell-permeable cAMP analog that fully inhibits and activates the sensors, respectively. Using this protocol, we observed different basal cAMP levels in primary mouse cardiomyocytes, thyroid cells and in 293A cells. The protocol can be generally applied for calibration of second messenger or metabolite concentrations measured by FRET, and for studying kinetics and pharmacological properties of their membrane-permeable analogs. The complete procedure, including cell preparation and FRET measurements, takes 3-6 d.
  Nature Protocol 04/2011; 6(4):427-38. · 8.36 Impact Factor
• Article: Cardiac beta1-adrenoceptor autoantibodies in human heart disease: rationale and design of the Etiology, Titre-Course, and Survival (ETiCS) Study.

  Nikolas Deubner, Dominik Berliner, Angela Schlipp, Götz Gelbrich, Alida L P Caforio, Stephan B Felix, Michael Fu, Hugo Katus, Christiane E Angermann, Martin J Lohse, Georg Ertl, Stefan Störk, Roland Jahns
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  ABSTRACT: Evidence for a pathophysiologic relevance of autoimmunity in human heart disease has substantially increased over the past years. Conformational autoantibodies stimulating the cardiac beta1-adrenoceptor (beta1-aabs) are considered of importance in heart failure development and clinical pilot studies have shown their prognostic significance in human 'idiopathic' cardiomyopathy. We recently developed a novel highly sensitive fluorescence-based functional assay to detect stimulating beta1-aabs. We will use this method to assess Etiology, Titre-Course, and effect on Survival (ETiCS) of beta1-aabs in a prospective multicentre study with serial follow-up of patients after a first acute myocarditis or myocardial infarction. Several European core laboratories will jointly study the hypothesis that both disorders may trigger autoimmune reactions leading to the generation of beta1-aabs and/or other heart-directed aabs. Further, sera from healthy controls and well-characterized patient cohorts with dilated, ischaemic, or hypertensive cardiomyopathy will be analysed retrospectively for beta1-aab prevalence, incidence, persistence, and/or clearance. ETiCS is so far the largest clinical diagnostic study projected to address cardiac autoimmunity. It attempts to unravel the pathophysiology of cardiac autoantibody formation and persistence/clearance. ETiCS will enhance current knowledge on autoimmunity in human heart disease and promote endeavours to develop novel therapies targeting cardiac aabs.
  European Journal of Heart Failure 07/2010; 12(7):753-62. · 4.90 Impact Factor
• Article: Targeting receptor antibodies in immune cardiomyopathy.

  Roland Jahns, Angela Schlipp, Valérie Boivin, Martin J Lohse
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  ABSTRACT: Although autoimmunity represents a well-established pathogenetic principle in several endocrine (Graves' disease), rheumatic (systemic lupus erythematosus), and neurological disorders (myasthenia gravis, multiple sclerosis), this mechanism has only recently gained more attention in cardiac diseases. Depending on individual genetic predisposition, heart-directed autoimmune reactions are supposed to emerge as a consequence of cardiomyocyte injury induced by inflammation, ischemia, or exposure to cardiotoxic substances. Myocyte apoptosis or necrosis and subsequent liberation of a "critical amount" of cardiac autoantigens may then induce a self-directed immune response, which in the worst case results in perpetuation of autoantibody-mediated cardiac damage. In particular, functionally active autoantibodies (aabs) directed against the cardiac beta1-adrenergic receptor (beta1-aabs) have been assigned a pivotal role in the pathogenesis of immune cardiomyopathy. Conformational beta1-aabs allosterically activate the sympathetic transmembrane signaling cascade, thereby increasing sarcoplasmatic cyclic adenosine monophosphate (cAMP) and calcium concentrations. Chronic cAMP production and calcium overload are cardiotoxic, leading to myocyte apoptosis, fibrotic repair, subsequent heart muscle dysfunction, and, finally, a dilative cardiomyopathic phenotype. Elimination by (extracorporeal) immunoadsorption or direct neutralization of the harmful receptor autoantibodies in the circulating blood represent promising strategies to protect the heart from beta1-(auto)antibody-induced damage.
  Seminars in Thrombosis and Hemostasis 03/2010; 36(2):212-8. · 4.52 Impact Factor
• Thesis: Study of the Primary and Secondary Metabolism of the Basidiomycete Omphalotus olearius by Means of Molecular Biology

  Angela Schlipp
  09/2007, Degree: Diploma, Supervisor: Prof. T. Anke; Dr. K. Eisfeld
• Article: The fatty acid synthase of the basidiomycete Omphalotus olearius is a single polypeptide.

  Luis Antelo, Angela Schlipp, Carolin Hof, Katrin Eisfeld, Holger Berg, Till Hornbogen, Rainer Zocher, Heidrun Anke
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  ABSTRACT: Fatty acids are essential components of almost all biological membranes. Additionally, they are important in energy storage, as second messengers during signal transduction, and in post-translational protein modification. De novo synthesis of fatty acids is essential for almost all organisms, and entails the iterative elongation of the growing fatty acid chain through a set of reactions conserved in all kingdoms. During our work on the biosynthesis of secondary metabolites, a 450-kDa protein was detected by SDS-PAGE of enriched fractions from mycelial lysates from the basidiomycete Omphalotus olearius. Protein sequencing of this protein band revealed the presence of peptides with homology to both alpha and beta subunits of the ascomycete fatty acid synthase (FAS) family. The FAS encoding gene of O. olearius was sequenced. The positions of its predicted 21 introns were verified. The gene encodes a 3931 amino acids single protein, with an equivalent of the ascomycetous beta subunit at the N-terminus and the a subunit at the C-terminus. This is the first report on an FAS protein from a homobasidiomycete and also the first fungal FAS which is comprised of a single polypeptide.
  Zeitschrift fur Naturforschung C 64(3-4):244-50. · 0.77 Impact Factor