A connection between the mitochondrial permeability transition pore, autophagy, and cerebral amyloidogenesis.

In a drug reprofiling attempt, we explored novel neuroprotective properties of 4-azasteroids by synthesizing chemical affinity tags capturing adenine nucleotide translocator-1, as a potential target. Dutasteride inhibits the mitochondrial transition pore and induces an increase of autophagosomal structures in human cell lines. In vivo, a surprising reduction of the beta-amyloid plaque load in a model for cerebral amyloidosis appears to connect release of neurotoxic peptides, mitochondrial apoptosis and autophagy.

Neuronal cell culture from human embryonic stem cells as in vitro model for neuroprotection.

In the context of efficacy testing of pharmacological compounds in animal models, replacement of some of these models with a relevant human in vitro system appears attractive, in particular with regard to large scale screening. Here, we show results from initial phases of a project, which attempts to explore the outstanding potential of human embryonic stem cell (hESC)-based in vitro models with special regard to neuronal stress as a potential replacement of animal models for human neurodegenerative diseases. We show the functionality of neurons derived from hESC precursors by calcium imaging, mitochondrial potential measurements and Western blots and moreover demonstrate that this model reproduces crucial mechanistic aspects observed during ischemia and excitotoxicity that are thought to be at the core of some neurodegenerative diseases.

Molecular analysis of homocysteic acid-induced neuronal stress.

Hyperhomocysteinemia is a risk factor for vascular and neuronal lesions often observed with concomitant high levels of homocysteic acid. In contrast to homocysteine, homocysteic acid induces calcium influx into neurons, with characteristics of an excitotoxic glutamatergic agonist at elevated concentrations. On the molecular level this is correlated to fast modifications of proteins (phosphorylation and proteolysis).

PD-L1-deficient mice show that PD-L1 on T cells, antigen-presenting cells, and host tissues negatively regulates T cells.

Both positive and negative regulatory roles have been suggested for the B7 family member PD-L1(B7-H1). PD-L1 is expressed on antigen-presenting cells (APCs), activated T cells, and a variety of tissues, but the functional significance of PD-L1 on each cell type is not yet clear. To dissect the functions of PD-L1 in vivo, we generated PD-L1-deficient (PD-L1(-/-)) mice.

Potential of comprehensive toxico-proteomics: quantitative and differential mining of functional proteomes from native samples.

It is becoming increasingly clear that the interactions of targets and biomarkers, drug modes of action and molecular mechanisms of side-effects and toxic effects are much more complex than previously anticipated, basically due to physiological compensation and cross-talk. Single genes often lead to hundreds or even thousands of functional protein molecules, modified at the post-translational level. Thus, the comprehensive analysis of proteins (proteomics) teaches us that physiological activity means dynamic, multidimensional processes among many thousands of different proteins within higher systems of organisation and correlation.

Neurotoxicity of active compounds--establishment of hESC-lines and proteomics technologies for human embryo- and neurotoxicity screening and biomarker identification.

Pharmaceutical and chemical industries are facing new challenges for hazard and risk assessment from regulatory agencies. Especially for potential embryotoxicity of active compounds, conclusions from animal testing remain problematic due to numerous species-specific effects. Developmental toxicity screening preferentially should be performed with human material.

Protein abundance quantification in embryonic stem cells using incomplete metabolic labelling with 15N amino acids, matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry, and analysis of relative isotopologue abundances of peptides.

An isotope dilution method for protein quantification is presented in the context of matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MALDI-TOFMS) and mass fingerprinting experiments, revealing an unappreciated high reproducibility and accuracy of relative peak intensity measurements. Labelled proteins were generated by growing cells in a medium containing (15)N-enriched amino acids, and were mixed with proteins of natural isotopic composition from control cells in ratios of approximately 0:1, 1:7, 1:2, 2:1, 7:1, and 1:0 (labelled/unlabelled). Mixtures were separated by two-dimensional gel electrophoresis and analysed by MALDI-TOFMS using typical experimental conditions.