Studies

Signal peptide peptidase-like 2c (SPPL2c) is the only member of the GxGD type intramembrane-cleaving aspartyl proteases that so far has not been assigned any substrates and thus its capability of proteolysis and its physiological function remain enigmatic. Based on a surprisingly high expression of SPPL2c in elongated spermatids we applied proteomics on a cellular model system with ectopic expression of SPPL2c and identified a variety of candidate substrates. The majority of these candidate ...

Here, we took advantage of well-defined mouse models for β-amyloidosis (APPPS1) to explore proteome changes in the cerebrospinal fluid which are related to these distinct proteopathic lesions. Non-targeted liquid chromatography-mass spectrometry revealed that the majority of proteins that undergo age- and disease-related changes in either mouse model was linked to microglia, and more specifically to previously described disease state-specific microglia transcriptomic signatures. The finding that ...

Spatial molecular profiling of complex tissues is essential to investigate cellular function in physiological and pathological states. However, methods for molecular analysis of biological specimens imaged in 3D as a whole are lacking. Here, we present DISCO-MS, a technology combining whole-organ/ism imaging, deep learning-based image analysis, robotic tissue extraction and ultra-high sensitivity mass spectrometry. DISCO-MS yielded qualitative and quantitative proteomics data indistinguishable ...

Inflammation in the central nervous system (CNS) can impair the function of neuronal mitochondria and contributes to axon degeneration in the common neuroinflammatory disease multiple sclerosis (MS). Here we combine cell type-specific mitochondrial proteomics with in vivo biosensor imaging to dissect how inflammation alters the molecular composition and functional capacity of neuronal mitochondria. Neuroinflammatory lesions in the mouse spinal cord cause widespread and persisting axonal ATP ...

The protease BACE1 is a major drug target for Alzheimer’s disease, but chronic BACE1 inhibition is associated with non-progressive worsening that may be caused by modulation of unknown physiological BACE1 substrates. To identify in vivo-relevant BACE1 substrates we applied pharmacoproteomics to non-human-primate cerebrospinal fluid (CSF) after acute treatment with BACE inhibitors. Besides SEZ6, the strongest, dose-dependent reduction was observed for the pro-inflammatory cytokine receptor ...

The beta-secretase BACE1 is a central drug target for Alzheimer’s disease. Clinically tested, BACE1-directed inhibitors also block the homologous protease BACE2. Yet, little is known about physiological BACE2 substrates and functions in vivo. Here, we performed glycoprotein enrichment and subsequent discovery proteomics to identify substrates of the protease BACE2 in plasma of mice. Therefore, we analysed plasma from BACE2 KO, BACE1/2 double KO and WT controls, as well as BACE1 KO with a separate ...

Signal peptide peptidase (SPP) and the four homologous SPP-like (SPPL) proteases constitute a family of intramembrane aspartyl proteases with selectivity for type II-oriented transmembrane segments. Here, we have analysed the physiological function of the orphan protease SPPL2c, previously considered to represent a non-expressed pseudogene. We identified proteolytic activity of SPPL2c towards selected tail-anchored proteins. Despite shared ER localization, SPPL2c and SPP exhibit distinct, though ...